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Articles by Tsuyoshi Miyakawa in JoVE
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تشريح التلفيف المسنن من الحصين ماوس الكبار
Hideo Hagihara1,2, Keiko Toyama1,2, Nobuyuki Yamasaki1,3, Tsuyoshi Miyakawa1,2,4,5
1Japan Science and Technology Agency, Core Research for Evolutionary Science and Technology (CREST), 2Division of Systems Medical Science, Institute for Comprehensive Medical Science, Fujita Health University, 3Department of Psychiatry, Graduate School of Medicine, Kyoto University, 4Genetic Engineering and Functional Genomics Group, Horizontal Medical Research Organization, Graduate School of Medicine, Kyoto University, 5Center for Genetic Analysis of Behavior, National Institute for Physiological Sciences, National Institutes of Natural Sciences
وأظهر تشريح تقنية لإزالة التلفيف المسنن من الماوس الكبار تحت stereomicroscope في هذا البروتوكول الفيديو المسجلة.
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T-المتاهة التناوب القسري والمهام التمييز بين اليسار واليمين لتقييم العمل ومرجع الذاكرة في الفئران
Hirotaka Shoji1,2, Hideo Hagihara1, Keizo Takao3, Satoko Hattori1,2,3, Tsuyoshi Miyakawa1,2,3
1Division of Systems Medical Science, Institute for Comprehensive Medical Science, Fujita Health University, 2Japan Science and Technology Agency, Core Research for Evolutionary Science and Technology (CREST), 3Center for Genetic Analysis of Behavior, National Institute for Physiological Sciences, National Institutes of Natural Sciences
هذا المقال يعرض بروتوكول تي المتاهة التجارب باستخدام جهاز تعديل آلية لتقييم وظائف التعلم والذاكرة لدى الفئران.
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السياقية وملقن الخوف تكييف اختبار باستخدام نظام تحليل الفيديو في الفئران
Hirotaka Shoji1,2, Keizo Takao2,3, Satoko Hattori1,2, Tsuyoshi Miyakawa1,2,3
1Division of Systems Medical Science, Institute for Comprehensive Medical Science, Fujita Health University, 2Japan Science and Technology Agency, Core Research for Evolutionary Science and Technology (CREST), 3Center for Genetic Analysis of Behavior, National Institute for Physiological Sciences, National Institutes of Natural Sciences
تقدم هذه المقالة بروتوكول لالسياقية وملقن الخوف تكييف الاختبار باستخدام نظام تحليل الفيديو لتقييم الخوف التعلم والذاكرة في الفئران.
Other articles by Tsuyoshi Miyakawa on PubMed
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Tight Junctions in Schwann Cells of Peripheral Myelinated Axons: a Lesson from Claudin-19-deficient Mice
The Journal of Cell Biology.
May, 2005 |
Pubmed ID: 15883201 Tight junction (TJ)-like structures have been reported in Schwann cells, but their molecular composition and physiological function remain elusive. We found that claudin-19, a novel member of the claudin family (TJ adhesion molecules in epithelia), constituted these structures. Claudin-19-deficient mice were generated, and they exhibited behavioral abnormalities that could be attributed to peripheral nervous system deficits. Electrophysiological analyses showed that the claudin-19 deficiency affected the nerve conduction of peripheral myelinated fibers. Interestingly, the overall morphology of Schwann cells lacking claudin-19 expression appeared to be normal not only in the internodal region but also at the node of Ranvier, except that TJs completely disappeared, at least from the outer/inner mesaxons. These findings have indicated that, similar to epithelial cells, Schwann cells also bear claudin-based TJs, and they have also suggested that these TJs are not involved in the polarized morphogenesis but are involved in the electrophysiological "sealing" function of Schwann cells.
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NFAT Dysregulation by Increased Dosage of DSCR1 and DYRK1A on Chromosome 21
Nature.
Jun, 2006 |
Pubmed ID: 16554754 Trisomy 21 results in Down's syndrome, but little is known about how a 1.5-fold increase in gene dosage produces the pleiotropic phenotypes of Down's syndrome. Here we report that two genes, DSCR1 and DYRK1A , lie within the critical region of human chromosome 21 and act synergistically to prevent nuclear occupancy of NFATc transcription factors, which are regulators of vertebrate development. We use mathematical modelling to predict that autoregulation within the pathway accentuates the effects of trisomy of DSCR1 and DYRK1A, leading to failure to activate NFATc target genes under specific conditions. Our observations of calcineurin-and Nfatc-deficient mice, Dscr1- and Dyrk1a-overexpressing mice, mouse models of Down's syndrome and human trisomy 21 are consistent with these predictions. We suggest that the 1.5-fold increase in dosage of DSCR1 and DYRK1A cooperatively destabilizes a regulatory circuit, leading to reduced NFATc activity and many of the features of Down's syndrome. More generally, these observations suggest that the destabilization of regulatory circuits can underlie human disease.
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Investigating Gene-to-behavior Pathways in Psychiatric Disorders: the Use of a Comprehensive Behavioral Test Battery on Genetically Engineered Mice
Annals of the New York Academy of Sciences.
Nov, 2006 |
Pubmed ID: 17185513 We have been investigating the relationships between genes and behaviors by conducting a systematic and well-defined behavioral test battery with mice that have a mutation on a gene of interest. The behavioral test battery covers a relatively broad range of various behavioral domains such as learning and memory, sensory-motor functions, emotion, motivation, and drug sensitivity/preference. Recently, we subjected mice lacking calcineurin (CN), a calcium/calmodulin protein phosphatase, to the comprehensive behavioral test battery. The mutant mice had a severe working memory deficit, increased locomotor activity, decreased social interaction, and impairments in prepulse and latent inhibition. The abnormalities of CN mutant mice were strikingly similar to those described for schizophrenic patients. Consistent with these findings, human genetics studies in a large sample of affected families detected a significant association of the PPP3CC gene, which encodes the CN gamma catalytic subunit with schizophrenia. The idea that abnormalities in the CN signaling pathway are involved in schizophrenia pathogenesis is consistent with traditional theories of schizophrenia and with many facts known about schizophrenia. A tremendous amount of knowledge about CN has accumulated and, by utilizing this information, the studies on the pathogenesis/pathophysiology of schizophrenia and its related mental disorders will be potentially accelerated. We discuss the potential impact of a large-scale mouse phenotyping project on the study of psychiatric disorders.
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Sept4, a Component of Presynaptic Scaffold and Lewy Bodies, is Required for the Suppression of Alpha-synuclein Neurotoxicity
Neuron.
Feb, 2007 |
Pubmed ID: 17296554 In Parkinson disease (PD), alpha-synuclein aggregates called Lewy bodies often involve and sequester Septin4 (Sept4), a polymerizing scaffold protein. However, the pathophysiological significance of this phenomenon is unclear. Here, we show the physiological association of Sept4 with alpha-synuclein, the dopamine transporter, and other presynaptic proteins in dopaminergic neurons; mice lacking Sept4 exhibit diminished dopaminergic neurotransmission due to scarcity of these presynaptic proteins. These data demonstrate an important role for septin scaffolds in the brain. In transgenic mice that express human alpha-synuclein(A53T) (a mutant protein responsible for familial PD), loss of Sept4 significantly enhances neuropathology and locomotor deterioration. In this PD model, insoluble deposits of Ser129-phosphorylated alpha-synuclein(A53T) are negatively correlated with the dosage of Sept4. In vitro, direct association with Sept4 protects alpha-synuclein against self-aggregation and Ser129 phosphorylation. Taken together, these data show that Sept4 may be involved in PD as a dual susceptibility factor, as its insufficiency can diminish dopaminergic neurotransmission and enhance alpha-synuclein neurotoxicity.
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Enriched Environments Influence Depression-related Behavior in Adult Mice and the Survival of Newborn Cells in Their Hippocampi
Behavioural Brain Research.
Jun, 2007 |
Pubmed ID: 17397941 Major depression is a highly prevalent mental disorder and environmental factors have been strongly implicated in its pathophysiology. Clinical studies have demonstrated that stress or depression can lead to atrophy and cell loss in the hippocampus. Studies of animal models of depression have suggested that reduced neurogenesis in the adult hippocampus might contribute to such structural changes and to the behavior of these animals. On the other hand, increased hippocampal neurogenesis can be induced by the administration of antidepressants or electroconvulsive seizure, suggesting that increased neurogenesis might be related to the treatment of depression. Thus, an enriched environment (EE), which also enhances neurogenesis, is expected to have therapeutic effects on depression-related behaviors. To investigate the effects of an EE during adulthood on these behaviors, we subjected adult mice housed in an EE for five weeks to behavioral tests. In an open field test, EE mice exhibited a decrease in the distance traveled and an increase in the amount of time spent in the center. The startle response was smaller in EE mice than in control mice. EE mice also showed reduced immobility time in a forced swim test. The immobility time in EE mice was approximately half that observed in mice treated with a tricyclic antidepressant, imipramine. In our experimental condition, increased survival of newborn cells was observed in EE mice by 5-bromo-2'-deoxyuridine (BrdU)-labeled immunohistochemistry. Double-staining of BrdU and a mature neuron marker, NeuN, revealed that the majority of surviving cells were neurons. Our results suggest that EE, which enhanced the survival of newborn neurons, shows beneficial effects on behavioral despair and habituation to a novel environment.
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Genetic Ablation of NMDA Receptor Subunit NR3B in Mouse Reveals Motoneuronal and Nonmotoneuronal Phenotypes
The European Journal of Neuroscience.
Sep, 2007 |
Pubmed ID: 17880385 NR3B is a modulatory subunit of the NMDA receptor, abundantly expressed in both cranial and spinal somatic motoneurons and at lower levels in other regions of the brain as well. Recently, we found the human NR3B gene (GRIN3B) to be highly genetically heterogeneous, and that approximately 10% of the normal European-American population lacks NR3B due to homozygous occurrence of a null allele in the gene. Therefore, it is especially important to understand the phenotypic consequences of the genetic loss of NR3B in both humans and animal models. We here provide results of behavioral analysis of mice genetically lacking NR3B, which is an ideal animal model due to homogeneity in genetic and environmental background. The NR3B(-/-) mice are viable and fertile. Consistent with the expression of NR3B in somatic motoneurons, the NR3B(-/-) mice showed a moderate but significant impairment in motor learning or coordination, and decreased activity in their home cages. Remarkably, the NR3B(-/-) mice showed a highly increased social interaction with their familiar cage mates in their home cage but moderately increased anxiety-like behaviour and decreased social interaction in a novel environment, consistent with the inhibitory role of NR3B on the functions of NMDA receptors. This work is the first reporting of the functional significance of NR3B in vivo and may give insight into the contribution of genetic variability of NR3B in the phenotypic heterogeneity among human population.
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Increased Social Interaction in Mice Deficient of the Striatal Medium Spiny Neuron-specific Phosphodiesterase 10A2
Journal of Neurochemistry.
Apr, 2008 |
Pubmed ID: 18088367 Cyclic nucleotide phosphodiesterase 10A (PDE10A) is a member of phosphodiesterase families that degrade cAMP and/or cGMP in distinct intracellular sites. PDE10A has a dual activity on hydrolysis of both cAMP and cGMP, and is prominently expressed in the striatum and the testis. Previous studies suggested that PDE10A is involved in regulation of locomotor activity and potentially related to psychosis, but concrete physiological roles of PDE10A remains elusive yet. In this study, we genetically inactivated PDE10A2, a prominent isoform of PDE10A in the brain, in mice, and demonstrate that PDE10A2 deficiency results in increased social interaction without any major influence on different other behaviors, along with increased levels of striatal cAMP. We also demonstrate that PDE10A2 is selectively distributed in medium spiny neurons, but not interneurons, of the striatal complex. Thus, our results establish a physiological role for PDE10A2 in regulating cAMP pathway and social interaction, and suggest that cAMP signaling cascade in striatal medium spiny neurons might be involved in regulating social interaction behavior in mice.
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Smaller Dendritic Spines, Weaker Synaptic Transmission, but Enhanced Spatial Learning in Mice Lacking Shank1
The Journal of Neuroscience : the Official Journal of the Society for Neuroscience.
Feb, 2008 |
Pubmed ID: 18272690 Experience-dependent changes in the structure of dendritic spines may contribute to learning and memory. Encoded by three genes, the Shank family of postsynaptic scaffold proteins are abundant and enriched in the postsynaptic density (PSD) of central excitatory synapses. When expressed in cultured hippocampal neurons, Shank promotes the maturation and enlargement of dendritic spines. Recently, Shank3 has been genetically implicated in human autism, suggesting an important role for Shank proteins in normal cognitive development. Here, we report the phenotype of Shank1 knock-out mice. Shank1 mutants showed altered PSD protein composition; reduced size of dendritic spines; smaller, thinner PSDs; and weaker basal synaptic transmission. Standard measures of synaptic plasticity were normal. Behaviorally, they had increased anxiety-related behavior and impaired contextual fear memory. Remarkably, Shank1-deficient mice displayed enhanced performance in a spatial learning task; however, their long-term memory retention in this task was impaired. These results affirm the importance of Shank1 for synapse structure and function in vivo, and they highlight a differential role for Shank1 in specific cognitive processes, a feature that may be relevant to human autism spectrum disorders.
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Increased Anxiety-like Behavior in Neuropsin (kallikrein-related Peptidase 8) Gene-deficient Mice
Behavioral Neuroscience.
Jun, 2008 |
Pubmed ID: 18513120 Neuropsin (kallikrein-related peptidase 8) is concentrated in the hippocampus, amygdala, olfactory bulb, and prefrontal cortex. Earlier studies showed that protease deficiency causes a significant impairment of early-phase long-term potentiation in the Schaffer collateral pathway and hippocampus-dependent memory in the Y maze and Morris water maze (Z. Chen et al., 1995; A. Hirata et al., 2001; H. Tamura et al., 2006). In addition to neuropsin's participation in the hippocampal memory, amygdalar and cortical localization of the gene suggests extrahippocampal behavioral function, and the authors therefore examined neuropsin-deficient mice, including tests of sensory motor reflex, open field, light-dark transition, Rota-Rod, elevated plus-maze, hot plate, startle response-prepulse inhibition, Porsolt forced swim, Barnes maze, eight-arm radial maze, and contextual and cued fear conditioning tests. Here, the authors found increased anxiety in neuropsin-deficient mice, suggesting the involvement of this protease in emotional responses.
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[Investigating Genes-to-behavior Pathways in Psychiatric Diseases: an Approach Using a Comprehensive Behavioral Test Battery on Genetically Engineered Mice]
Nihon Shinkei Seishin Yakurigaku Zasshi = Japanese Journal of Psychopharmacology.
Jun, 2008 |
Pubmed ID: 18646600 We have been investigating the relationships between genes and behaviors by conducting a systematic and well-defined behavioral test battery with mice that have a mutation on a gene of interest. The behavioral test battery covers a relatively broad range of various behavioral domains such as learning and memory, sensory-motor functions, emotion, motivation, and drug sensitivity/preference. Recently, we subjected mice lacking calcineurin (CN), a calcium/calmodulin protein phosphatase, to the comprehensive behavioral test battery. The mutant mice had a severe working memory deficit, increased locomotor activity, decreased social interaction, and impairments in prepulse and latent inhibition. The abnormalities of CN mutant mice were strikingly similar to those described for schizophrenic patients. Consistent with these findings, human genetics studies in a large sample of affected families detected a significant association of the PPP3CC gene, which encodes the CN gamma catalytic subunit with schizophrenia. The idea that abnormalities in the CN signaling pathway are involved in schizophrenia pathogenesis is consistent with traditional theories of schizophrenia and with many facts known about schizophrenia. A tremendous amount of knowledge about CN has accumulated and, by utilizing this information, the studies on the pathogenesis/pathophysiology of schizophrenia and its related mental disorders will be potentially accelerated. We discuss the potential impact of a large-scale mouse phenotyping project on the study of psychiatric disorders.
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Identification of YWHAE, a Gene Encoding 14-3-3epsilon, As a Possible Susceptibility Gene for Schizophrenia
Human Molecular Genetics.
Oct, 2008 |
Pubmed ID: 18658164 Schizophrenia is a complex mental disorder with a fairly high degree of heritability. Although the causes of schizophrenia remain unclear, it is now widely accepted that it is a neurodevelopmental and neurodegenerative disorder involving disconnectivity and disorder of the synapses. Disrupted-in-schizophrenia 1 (DISC1) is a promising candidate susceptibility gene involved in neurodevelopment, including maturation of the cerebral cortex. To identify other susceptibility genes for schizophrenia, we screened for DISC1-interacting molecules [NudE-like (NUDEL), Lissencephaly-1 (LIS1), 14-3-3epsilon (YWHAE), growth factor receptor bound protein 2 (GRB2) and Kinesin family 5A of Kinesen1 (KIF5A)], assessing a total of 25 tagging single-nucleotide polymorphisms (SNPs) in a Japanese population. We identified a YWHAE SNP (rs28365859) that showed a highly significant difference between case and control samples, with higher minor allele frequencies in controls (P(allele) = 1.01 x 10(-5) and P(genotype) = 4.08 x 10(-5) in 1429 cases and 1728 controls). Both messenger RNA transcription and protein expression of 14-3-3epsilon were also increased in the lymphocytes of healthy control subjects harboring heterozygous and homozygous minor alleles compared with homozygous major allele subjects. To further investigate a potential role for YWHAE in schizophrenia, we studied Ywhae(+/-) mice in which the level of 14-3-3epsilon protein is reduced to 50% of that in wild-type littermates. These mice displayed weak defects in working memory in the eight-arm radial maze and moderately enhanced anxiety-like behavior in the elevated plus-maze. Our results suggest that YWHAE is a possible susceptibility gene that functions protectively in schizophrenia.
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Alpha-CaMKII Deficiency Causes Immature Dentate Gyrus, a Novel Candidate Endophenotype of Psychiatric Disorders
Molecular Brain.
2008 |
Pubmed ID: 18803808 Elucidating the neural and genetic factors underlying psychiatric illness is hampered by current methods of clinical diagnosis. The identification and investigation of clinical endophenotypes may be one solution, but represents a considerable challenge in human subjects. Here we report that mice heterozygous for a null mutation of the alpha-isoform of calcium/calmodulin-dependent protein kinase II (alpha-CaMKII+/-) have profoundly dysregulated behaviours and impaired neuronal development in the dentate gyrus (DG). The behavioral abnormalities include a severe working memory deficit and an exaggerated infradian rhythm, which are similar to symptoms seen in schizophrenia, bipolar mood disorder and other psychiatric disorders. Transcriptome analysis of the hippocampus of these mutants revealed that the expression levels of more than 2000 genes were significantly changed. Strikingly, among the 20 most downregulated genes, 5 had highly selective expression in the DG. Whereas BrdU incorporated cells in the mutant mouse DG was increased by more than 50 percent, the number of mature neurons in the DG was dramatically decreased. Morphological and physiological features of the DG neurons in the mutants were strikingly similar to those of immature DG neurons in normal rodents. Moreover, c-Fos expression in the DG after electric footshock was almost completely and selectively abolished in the mutants. Statistical clustering of human post-mortem brains using 10 genes differentially-expressed in the mutant mice were used to classify individuals into two clusters, one of which contained 16 of 18 schizophrenic patients. Nearly half of the differentially-expressed probes in the schizophrenia-enriched cluster encoded genes that are involved in neurogenesis or in neuronal migration/maturation, including calbindin, a marker for mature DG neurons. Based on these results, we propose that an "immature DG" in adulthood might induce alterations in behavior and serve as a promising candidate endophenotype of schizophrenia and other human psychiatric disorders.
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Mice Lacking the Kf-1 Gene Exhibit Increased Anxiety- but Not Despair-like Behavior
Frontiers in Behavioral Neuroscience.
2008 |
Pubmed ID: 18958194 KF-1 was originally identified as a protein encoded by human gene with increased expression in the cerebral cortex of a patient with Alzheimer's disease. In mouse brain, kf-1 mRNA is detected predominantly in the hippocampus and cerebellum, and kf-1 gene expression is elevated also in the frontal cortex of rats after chronic antidepressant treatments. KF-1 mediates E2-dependent ubiquitination and may modulate cellular protein levels as an E3 ubiquitin ligase, though its target proteins are not yet identified. To elucidate the role of kf-1 in the central nervous system, we generated kf-1 knockout mice by gene targeting, using Cre-lox recombination. The resulting kf-1(-/-) mice were normal and healthy in appearance. Behavioral analyses revealed that kf-1(-/-) mice showed significantly increased anxiety-like behavior compared with kf-1(+/+) littermates in the light/dark transition and elevated plus maze tests; however, no significant differences were observed in exploratory locomotion using the open field test or in behavioral despair using the forced swim and tail suspension tests. These observations suggest that KF-1 suppresses selectively anxiety under physiological conditions probably through modulating protein levels of its unknown target(s). Interestingly, kf-1(-/-) mice exhibited significantly increased prepulse inhibition, which is usually reduced in human schizophrenic patients. Thus, the kf-1(-/-) mice provide a novel animal model for elucidating molecular mechanisms of psychiatric diseases such as anxiety/depression, and may be useful for screening novel anxiolytic/antidepressant compounds.
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Down-regulation of Protocadherin-alpha A Isoforms in Mice Changes Contextual Fear Conditioning and Spatial Working Memory
The European Journal of Neuroscience.
Oct, 2008 |
Pubmed ID: 18973563 Diverse protocadherins (Pcdhs), which are encoded as a large cluster (composed of alpha, beta and gamma clusters) in the genome, are localized to axons and synapses. The Pcdhs have been proposed to contribute to the generation of sophisticated neural networks and to regulate brain function. To address the molecular roles of Pcdhs in regulating individual behavior, here we generated knockdown mice of Pcdh-alpha proteins and examined their behavioral abnormalities. There are two alternative splicing variants of the Pcdh-alpha constant region, Pcdh-alpha A and B isoforms, with different cytoplasmic tails. Pcdh-alpha(DeltaBneo/DeltaBneo) mice, in which the Pcdh-alpha B splicing variant was absent and the Pcdh-alpha A isoforms were down-regulated to approximately 20% of the wild-type level, exhibited enhanced contextual fear conditioning and disparities in an eight-arm radial maze. Similar abnormalities were found in Pcdh-alpha(DeltaAneo/DeltaAneo) mice, which lacked 57 amino acids of the Pcdh-alpha A cytoplasmic tail. These learning abnormalities were, however, not seen in Pcdh-alpha(DeltaB/DeltaB) mice [in which the neomycin-resistance (neo) gene cassette was removed from the Pcdh-alpha(DeltaBneo/DeltaBneo) alleles], in which the expression level of the Pcdh-alpha A isoforms was recovered, although the Pcdh-alpha B isoforms were still completely missing in the brain. In addition, the amount of 5-hydroxytryptamine increased in the hippocampus of the hypomorphic Pcdh-alpha A mutant mice but not in recovery Pcdh-alpha(DeltaB/DeltaB). These results suggested that the level of Pcdh-alpha A isoforms in the brain has an important role in regulating learning and memory functions and the amount of 5-hydroxytryptamine in the hippocampus.
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Mice with Altered Myelin Proteolipid Protein Gene Expression Display Cognitive Deficits Accompanied by Abnormal Neuron-glia Interactions and Decreased Conduction Velocities
The Journal of Neuroscience : the Official Journal of the Society for Neuroscience.
Jul, 2009 |
Pubmed ID: 19571127 Conduction velocity (CV) of myelinated axons has been shown to be regulated by oligodendrocytes even after myelination has been completed. However, how myelinating oligodendrocytes regulate CV, and what the significance of this regulation is for normal brain function remain unknown. To address these questions, we analyzed a transgenic mouse line harboring extra copies of the myelin proteolipid protein 1 (plp1) gene (plp1(tg/-) mice) at 2 months of age. At this stage, the plp1(tg/-) mice have an unaffected myelin structure with a normally appearing ion channel distribution, but the CV in all axonal tracts tested in the CNS is greatly reduced. We also found decreased axonal diameters and slightly abnormal paranodal structures, both of which can be a cause for the reduced CV. Interestingly the plp1(tg/-) mice showed altered anxiety-like behaviors, reduced prepulse inhibitions, spatial learning deficits and working memory deficit, all of which are schizophrenia-related behaviors. Our results implicate that abnormalities in the neuron-glia interactions at the paranodal junctions can result in reduced CV in the CNS, which then induces behavioral abnormalities related to schizophrenia.
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Neural Activity Changes Underlying the Working Memory Deficit in Alpha-CaMKII Heterozygous Knockout Mice
Frontiers in Behavioral Neuroscience.
2009 |
Pubmed ID: 19750198 The alpha-isoform of calcium/calmodulin-dependent protein kinase II (alpha-CaMKII) is expressed abundantly in the forebrain and is considered to have an essential role in synaptic plasticity and cognitive function. Previously, we reported that mice heterozygous for a null mutation of alpha-CaMKII (alpha-CaMKII+/-) have profoundly dysregulated behaviors including a severe working memory deficit, which is an endophenotype of schizophrenia and other psychiatric disorders. In addition, we found that almost all the neurons in the dentate gyrus (DG) of the mutant mice failed to mature at molecular, morphological and electrophysiological levels. In the present study, to identify the brain substrates of the working memory deficit in the mutant mice, we examined the expression of the immediate early genes (IEGs), c-Fos and Arc, in the brain after a working memory version of the eight-arm radial maze test. c-Fos expression was abolished almost completely in the DG and was reduced significantly in neurons in the CA1 and CA3 areas of the hippocampus, central amygdala, and medial prefrontal cortex (mPFC). However, c-Fos expression was intact in the entorhinal and visual cortices. Immunohistochemical studies using arc promoter driven dVenus transgenic mice demonstrated that arc gene activation after the working memory task occurred in mature, but not immature neurons in the DG of wild-type mice. These results suggest crucial insights for the neural circuits underlying spatial mnemonic processing during a working memory task and suggest the involvement of alpha-CaMKII in the proper maturation and integration of DG neurons into these circuits.
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KF-1 Ubiquitin Ligase: An Anxiety Suppressor
Frontiers in Neuroscience.
May, 2009 |
Pubmed ID: 19753093 Anxiety is an instinct that may have developed to promote adaptive survival by evading unnecessary danger. However, excessive anxiety is disruptive and can be a basic disorder of other psychiatric diseases such as depression. The KF-1, a ubiquitin ligase located on the endoplasmic reticulum (ER), may prevent excessive anxiety; kf-1(-/-) mice exhibit selectively elevated anxiety-like behavior against light or heights. It is surmised that KF-1 degrades some target proteins, responsible for promoting anxiety, through the ER-associated degradation pathway, similar to Parkin in Parkinson's disease (PD). Parkin, another ER-ubiquitin ligase, prevents the degeneration of dopaminergic neurons by degrading the target proteins responsible for PD. Molecular phylogenetic studies have revealed that the prototype of kf-1 appeared in the very early phase of animal evolution but was lost, unlike parkin, in the lineage leading up to Drosophila. Therefore, kf-1(-/-) mice may be a powerful tool for elucidating the molecular mechanisms involved in emotional regulation, and for screening novel anxiolytic/antidepressant compounds.
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Nardilysin Regulates Axonal Maturation and Myelination in the Central and Peripheral Nervous System
Nature Neuroscience.
Dec, 2009 |
Pubmed ID: 19935654 Axonal maturation and myelination are essential processes for establishing an efficient neuronal signaling network. We found that nardilysin (N-arginine dibasic convertase, also known as Nrd1 and NRDc), a metalloendopeptidase enhancer of protein ectodomain shedding, is a critical regulator of these processes. Nrd1-/- mice had smaller brains and a thin cerebral cortex, in which there were less myelinated fibers with thinner myelin sheaths and smaller axon diameters. We also found hypomyelination in the peripheral nervous system (PNS) of Nrd1-/- mice. Neuron-specific overexpression of NRDc induced hypermyelination, indicating that the level of neuronal NRDc regulates myelin thickness. Consistent with these findings, Nrd1-/- mice had impaired motor activities and cognitive deficits. Furthermore, NRDc enhanced ectodomain shedding of neuregulin1 (NRG1), which is a master regulator of myelination in the PNS. On the basis of these data, we propose that NRDc regulates axonal maturation and myelination in the CNS and PNS, in part, through the modulation of NRG1 shedding.
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Comprehensive Behavioral Analysis of Calcium/calmodulin-dependent Protein Kinase IV Knockout Mice
PloS One.
2010 |
Pubmed ID: 20209163 Calcium-calmodulin dependent protein kinase IV (CaMKIV) is a protein kinase that activates the transcription factor CREB, the cyclic AMP-response element binding protein. CREB is a key transcription factor in synaptic plasticity and memory consolidation. To elucidate the behavioral effects of CaMKIV deficiency, we subjected CaMKIV knockout (CaMKIV KO) mice to a battery of behavioral tests. CaMKIV KO had no significant effects on locomotor activity, motor coordination, social interaction, pain sensitivity, prepulse inhibition, attention, or depression-like behavior. Consistent with previous reports, CaMKIV KO mice exhibited impaired retention in a fear conditioning test 28 days after training. In contrast, however, CaMKIV KO mice did not show any testing performance deficits in passive avoidance, one of the most commonly used fear memory paradigms, 28 days after training, suggesting that remote fear memory is intact. CaMKIV KO mice exhibited intact spatial reference memory learning in the Barnes circular maze, and normal spatial working memory in an eight-arm radial maze. CaMKIV KO mice also showed mildly decreased anxiety-like behavior, suggesting that CaMKIV is involved in regulating emotional behavior. These findings indicate that CaMKIV might not be essential for fear memory or spatial memory, although it is possible that the activities of other neural mechanisms or signaling pathways compensate for the CaMKIV deficiency.
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Behavioral Profiles of Three C57BL/6 Substrains
Frontiers in Behavioral Neuroscience.
2010 |
Pubmed ID: 20676234 C57BL/6 inbred strains of mice are widely used in knockout and transgenic research. To evaluate the loss-of-function and gain-of-function effects of the gene of interest, animal behaviors are often examined. However, an issue of C57BL/6 substrains that is not always appreciated is that behaviors are known to be strongly influenced by genetic background. To investigate the behavioral characteristics of C57BL/6 substrains, we subjected C57BL/6J, C57BL/6N, and C57BL/6C mice to a behavior test battery. We performed both a regular scale analysis, in which experimental conditions were tightly controlled, and large-scale analysis from large number of behavioral data that we have collected so far through the comprehensive behavioral test battery applied to 700-2,200 mice in total. Significant differences among the substrains were found in the results of various behavioral tests, including the open field, rotarod, elevated plus maze, prepulse inhibition, Porsolt forced swim, and spatial working memory version of the eight-arm radial maze. Our results show a divergence of behavioral performance in C57BL/6 substrains, which suggest that small genetic differences may have a great influence on behavioral phenotypes. Thus, the genetic background of different substrains should be carefully chosen, equated, and considered in the interpretation of mutant behavioral phenotypes.
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Expression of Tryptophan 2,3-dioxygenase in Mature Granule Cells of the Adult Mouse Dentate Gyrus
Molecular Brain.
2010 |
Pubmed ID: 20815922 New granule cells are continuously generated in the dentate gyrus of the adult hippocampus. During granule cell maturation, the mechanisms that differentiate new cells not only describe the degree of cell differentiation, but also crucially regulate the progression of cell differentiation. Here, we describe a gene, tryptophan 2,3-dioxygenase (TDO), whose expression distinguishes stem cells from more differentiated cells among the granule cells of the adult mouse dentate gyrus. The use of markers for proliferation, neural progenitors, and immature and mature granule cells indicated that TDO was expressed in mature cells and in some immature cells. In mice heterozygous for the alpha-isoform of calcium/calmodulin-dependent protein kinase II, in which dentate gyrus granule cells fail to mature normally, TDO immunoreactivity was substantially downregulated in the dentate gyrus granule cells. Moreover, a 5-bromo-2'-deoxyuridine labeling experiment revealed that new neurons began to express TDO between 2 and 4 wk after the neurons were generated, when the axons and dendrites of the granule cells developed and synaptogenesis occurred. These findings indicate that TDO might be required at a late-stage of granule cell development, such as during axonal and dendritic growth, synaptogenesis and its maturation.
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Decreased Exploratory Activity in a Mouse Model of 15q Duplication Syndrome; Implications for Disturbance of Serotonin Signaling
PloS One.
2010 |
Pubmed ID: 21179543 Autism spectrum disorders (ASDs) have garnered significant attention as an important grouping of developmental brain disorders. Recent genomic studies have revealed that inherited or de novo copy number variations (CNVs) are significantly involved in the pathophysiology of ASDs. In a previous report from our laboratory, we generated mice with CNVs as a model of ASDs, with a duplicated mouse chromosome 7C that is orthologous to human chromosome 15q11-13. Behavioral analyses revealed paternally duplicated (patDp/+) mice displayed abnormal behaviors resembling the symptoms of ASDs. In the present study, we extended these findings by performing various behavioral tests with C57BL/6J patDp/+ mice, and comprehensively measuring brain monoamine levels with ex vivo high performance liquid chromatography. Compared with wild-type controls, patDp/+ mice exhibited decreased locomotor and exploratory activities in the open field test, Y-maze test, and fear-conditioning test. Furthermore, their decreased activity levels overcame increased appetite induced by 24 hours of food deprivation in the novelty suppressed feeding test. Serotonin levels in several brain regions of adult patDp/+ mice were lower than those of wild-type control, with no concurrent changes in brain levels of dopamine or norepinephrine. Moreover, analysis of monoamines in postnatal developmental stages demonstrated reduced brain levels of serotonin in young patDp/+ mice. These findings suggest that a disrupted brain serotonergic system, especially during postnatal development, may generate the phenotypes of patDp/+ mice.
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Forebrain-specific Constitutively Active CaMKKα Transgenic Mice Show Deficits in Hippocampus-dependent Long-term Memory
Neurobiology of Learning and Memory.
Sep, 2011 |
Pubmed ID: 21558011 The Ca(2+)/calmodulin (CaM) kinase cascade is activated by Ca(2+) influx through the voltage-dependent Ca(2+) channels and the NMDA receptor. CaM kinase kinase (CaMKK), the most upstream kinase of the CaM kinase cascade, phosphorylates and activates both CaM kinase I (CaMKI) and CaMKIV, resulting in activation of cyclic AMP-responsive element binding protein (CREB)-dependent gene transcription. Using transgenic techniques, we created mutant mice in which a constitutively active form of CaMKK1, the autoinhibitory domain truncated protein, is over-expressed specifically in the forebrain. In these mice, although performance was normal in basal activity and short-term memory, specific impairments were shown in hippocampus-dependent long-term memory after training in spatial memory tasks and after contextual fear conditioning. In cultured neurons of these mice, phosphorylation of CaMKI was significantly increased in basal states, whereas the activity range of CaMKI phosphorylation by brain-derived neurotrophic factor (BDNF) and KCl stimulation was significantly diminished in mutant mice. Our results define a critical role for CaMKKα in synaptic plasticity and the retention of hippocampus-dependent long-term memory.
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P301S Mutant Human Tau Transgenic Mice Manifest Early Symptoms of Human Tauopathies with Dementia and Altered Sensorimotor Gating
PloS One.
2011 |
Pubmed ID: 21698260 Tauopathies are neurodegenerative disorders characterized by the accumulation of abnormal tau protein leading to cognitive and/or motor dysfunction. To understand the relationship between tau pathology and behavioral impairments, we comprehensively assessed behavioral abnormalities in a mouse tauopathy model expressing the human P301S mutant tau protein in the early stage of disease to detect its initial neurological manifestations. Behavioral abnormalities, shown by open field test, elevated plus-maze test, hot plate test, Y-maze test, Barnes maze test, Morris water maze test, and/or contextual fear conditioning test, recapitulated the neurological deficits of human tauopathies with dementia. Furthermore, we discovered that prepulse inhibition (PPI), a marker of sensorimotor gating, was enhanced in these animals concomitantly with initial neuropathological changes in associated brain regions. This finding provides evidence that our tauopathy mouse model displays neurofunctional abnormalities in prodromal stages of disease, since enhancement of PPI is characteristic of amnestic mild cognitive impairment, a transitional stage between normal aging and dementia such as Alzheimer's disease (AD), in contrast with attenuated PPI in AD patients. Therefore, assessment of sensorimotor gating could be used to detect the earliest manifestations of tauopathies exemplified by prodromal AD, in which abnormal tau protein may play critical roles in the onset of neuronal dysfunctions.
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Relaxin-3-deficient Mice Showed Slight Alteration in Anxiety-related Behavior
Frontiers in Behavioral Neuroscience.
2011 |
Pubmed ID: 21887138 Relaxin-3 is a neuropeptide belonging to the relaxin/insulin superfamily. Studies using rodents have revealed that relaxin-3 is predominantly expressed in neurons in the nucleus incertus (NI) of the pons, the axons of which project to forebrain regions including the hypothalamus. There is evidence that relaxin-3 is involved in several functions, including food intake and stress responses. In the present study, we generated relaxin-3 gene knockout (KO) mice and examined them using a range of behavioral tests of sensory/motor functions and emotion-related behaviors. The results revealed that relaxin-3 KO mice exhibited normal growth and appearance, and were generally indistinguishable from wild genotype littermates. There was no difference in bodyweight among genotypes until at least 28 weeks after birth. In addition, there were no significant differences between wild-type and KO mice in locomotor activity, social interaction, hot plate test performance, fear conditioning, depression-like behavior, and Y-maze test performance. However, in the elevated plus maze test, KO mice exhibited a robust increase in the tendency to enter open arms, although they exhibited normal performance in a light/dark transition test and showed no difference from wild-type mice in the time spent in central area in the open field test. On the other hand, a significant increase in the acoustic startle response was observed in KO mice. These results indicate that relaxin-3 is slightly involved in the anxiety-related behavior.
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Expression of the AMPA Receptor Subunits GluR1 and GluR2 is Associated with Granule Cell Maturation in the Dentate Gyrus
Frontiers in Neuroscience.
2011 |
Pubmed ID: 21927594 The dentate gyrus produces new granule neurons throughout adulthood in mammals from rodents to humans. During granule cell maturation, defined markers are expressed in a highly regulated sequential process, which is necessary for directed neuronal differentiation. In the present study, we show that α-amino-3-hydroxy-5-methy-4-isoxazole propionate (AMPA) receptor subunits GluR1 and GluR2 are expressed in differentiated granule cells, but not in stem cells, in neonatal, and adult dentate gyrus. Using markers for neural progenitors, immature and mature granule cells, we found that GluR1 and GluR2 were expressed mainly in mature cells and in some immature cells. A time-course analysis of 5-bromo-2'-deoxyuridine staining revealed that granule cells express GluR1 around 3 weeks after being generated. In mice heterozygous for the alpha-isoform of calcium/calmodulin-dependent protein kinase II, a putative animal model of schizophrenia and bipolar disorder in which dentate gyrus granule cells fail to mature normally, GluR1 and GluR2 immunoreactivities were substantially downregulated in the dentate gyrus granule cells. In the granule cells of mutant mice, the expression of both presynaptic and postsynaptic markers was decreased, suggesting that GluR1 and GluR2 are also associated with synaptic maturation. Moreover, GluR1 and GluR2 were also expressed in mature granule cells of the neonatal dentate gyrus. Taken together, these findings indicate that GluR1 and GluR2 expression closely correlates with the neuronal maturation state, and that GluR1 and GluR2 are useful markers for mature granule cells in the dentate gyrus.
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Adenomatous Polyposis Coli Heterozygous Knockout Mice Display Hypoactivity and Age-dependent Working Memory Deficits
Frontiers in Behavioral Neuroscience.
2011 |
Pubmed ID: 22347851 A tumor suppressor gene, Adenomatous polyposis coli (Apc), is expressed in the nervous system from embryonic to adulthood stages, and transmits the Wnt signaling pathway in which schizophrenia susceptibility genes, including T-cell factor 4 (TCF4) and calcineurin (CN), are involved. However, the functions of Apc in the nervous system are largely unknown. In this study, as the first evaluation of Apc function in the nervous system, we have investigated the behavioral significance of the Apc gene, applying a battery of behavioral tests to Apc heterozygous knockout (Apc(+/-)) mice. Apc(+/-) mice showed no significant impairment in neurological reflexes or sensory and motor abilities. In various tests, including light/dark transition, open-field, social interaction, eight-arm radial maze, and fear conditioning tests, Apc(+/-) mice exhibited hypoactivity. In the eight-arm radial maze, Apc(+/-) mice 6-7 weeks of age displayed almost normal performance, whereas those 11-12 weeks of age showed a severe performance deficit in working memory, suggesting that Apc is involved in working memory performance in an age-dependent manner. The possibility that anemia, which Apc(+/-) mice develop by 17 weeks of age, impairs working memory performance, however, cannot be excluded. Our results suggest that Apc plays a role in the regulation of locomotor activity and presumably working memory performance.
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Right-hemispheric Dominance of Spatial Memory in Split-brain Mice
Hippocampus.
Feb, 2012 |
Pubmed ID: 21069782 Left-right asymmetry of human brain function has been known for a century, although much of molecular and cellular basis of brain laterality remains to be elusive. Recent studies suggest that hippocampal CA3-CA1 excitatory synapses are asymmetrically arranged, however, the functional implication of the asymmetrical circuitry has not been studied at the behavioral level. In order to address the left-right asymmetry of hippocampal function in behaving mice, we analyzed the performance of "split-brain" mice in the Barnes maze. The "split-brain" mice received ventral hippocampal commissure and corpus callosum transection in addition to deprivation of visual input from one eye. In such mice, the hippocampus in the side of visual deprivation receives sensory-driven input. Better spatial task performance was achieved by the mice which were forced to use the right hippocampus than those which were forced to use the left hippocampus. In two-choice spatial maze, forced usage of left hippocampus resulted in a comparable performance to the right counterpart, suggesting that both hippocampal hemispheres are capable of conducting spatial learning. Therefore, the results obtained from the Barnes maze suggest that the usage of the right hippocampus improves the accuracy of spatial memory. Performance of non-spatial yet hippocampus-dependent tasks (e.g. fear conditioning) was not influenced by the laterality of the hippocampus. © 2010 Wiley Periodicals, Inc.
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Comprehensive Behavioral Analysis of ENU-induced Disc1-Q31L and -L100P Mutant Mice
BMC Research Notes.
Feb, 2012 |
Pubmed ID: 22348257 ABSTRACT: BACKGROUND: Disrupted-in-Schizophrenia 1 (DISC1) is considered to be a candidate susceptibility gene for psychiatric disorders, including schizophrenia, bipolar disorder, and major depression. A recent study reported that N-ethyl-N-nitrosourea (ENU)-induced mutations in exon 2 of the mouse Disc1 gene, which resulted in the amino acid exchange of Q31L and L100P, caused an increase in depression-like behavior in 31 L mutant mice and schizophrenia-like behavior in 100P mutant mice; thus, these are potential animal models of psychiatric disorders. However, remaining heterozygous mutations that possibly occur in flanking genes other than Disc1 itself might induce behavioral abnormalities in the mutant mice. Here, to confirm the effects of Disc1-Q31L and Disc1-L100P mutations on behavioral phenotypes and to investigate the behaviors of the mutant mice in more detail, the mutant lines were backcrossed to C57BL/6JJcl through an additional two generations and the behaviors were analyzed using a comprehensive behavioral test battery. RESULTS: Contrary to expectations, 31 L mutant mice showed no significant behavioral differences when compared with wild-type control mice in any of the behavioral tests, including the Porsolt forced swim and tail suspension tests, commonly used tests for depression-like behavior. Also, 100P mutant mice exhibited no differences in almost all of the behavioral tests, including the prepulse inhibition test for measuring sensorimotor gating, which is known to be impaired in schizophrenia patients; however, 100P mutant mice showed higher locomotor activity compared with wild-type control mice in the light/dark transition test. CONCLUSIONS: Although these results are partially consistent with the previous study in that there was hyperactivity in 100P mutant mice, the vast majority of the results are inconsistent with those of the previous study; this discrepancy may be explained by differences in the genetic background of the mice, the laboratory environment, experimental protocols, and more. Further behavioral studies under various experimental conditions are necessary to determine whether these Disc1 mutant mouse lines are suitable animal models of schizophrenia and major depression.
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M4 Muscarinic Receptor Knockout Mice Display Abnormal Social Behavior and Decreased Prepulse Inhibition
Molecular Brain.
2012 |
Pubmed ID: 22463818 In the central nervous system (CNS), the muscarinic system plays key roles in learning and memory, as well as in the regulation of many sensory, motor, and autonomic processes, and is thought to be involved in the pathophysiology of several major diseases of the CNS, such as Alzheimer's disease, depression, and schizophrenia. Previous studies reveal that M4 muscarinic receptor knockout (M4R KO) mice displayed an increase in basal locomotor activity, an increase in sensitivity to the prepulse inhibition (PPI)-disrupting effect of psychotomimetics, and normal basal PPI. However, other behaviorally significant roles of M4R remain unclear.
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Comprehensive Behavioral Analysis of Pituitary Adenylate Cyclase-activating Polypeptide (PACAP) Knockout Mice
Frontiers in Behavioral Neuroscience.
2012 |
Pubmed ID: 23060763 Pituitary adenylate cyclase-activating polypeptide (PACAP) is a neuropeptide acting as a neurotransmitter, neuromodulator, or neurotrophic factor. PACAP is widely expressed throughout the brain and exerts its functions through the PACAP-specific receptor (PAC(1)). Recent studies reveal that genetic variants of the PACAP and PAC(1) genes are associated with mental disorders, and several behavioral abnormalities of PACAP knockout (KO) mice are reported. However, an insufficient number of backcrosses was made using PACAP KO mice on the C57BL/6J background due to their postnatal mortality. To elucidate the effects of PACAP on neuropsychiatric function, the PACAP gene was knocked out in F1 hybrid mice (C57BL/6J × 129SvEv) for appropriate control of the genetic background. The PACAP KO mice were then subjected to a behavioral test battery. PACAP deficiency had no significant effects on neurological screen. As shown previously, the mice exhibited significantly increased locomotor activity in a novel environment and abnormal anxiety-like behavior, while no obvious differences between genotypes were shown in home cage (HC) activity. In contrast to previous reports, the PACAP KO mice showed normal prepulse inhibition (PPI) and slightly decreased depression-like behavior. Previous study demonstrates that the social interaction (SI) in a resident-intruder test was decreased in PACAP KO mice. On the other hand, we showed that PACAP KO mice exhibited increased SI in Crawley's three-chamber social approach test, although PACAP KO had no significant impact on SI in a HC. PACAP KO mice also exhibited mild performance deficit in working memory in an eight-arm radial maze (RM) and the T-maze (TM), while they did not show any significant abnormalities in the left-right discrimination task in the TM. These results suggest that PACAP has an important role in the regulation of locomotor activity, social behavior, anxiety-like behavior and, potentially, working memory.
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Increased Astrocytic ATP Release Results in Enhanced Excitability of the Hippocampus
Glia.
Feb, 2013 |
Pubmed ID: 23018918 Astrocytes, a major subtype of glia, interact with neurons as a supportive partner supplying energy sources and growth factors. Astrocytes regulate the activity of neighboring neurons by releasing chemical transmitters (gliotransmitters). However, the precise role of gilotransmitters in regulating neuronal activity is still under debate. Here, we report that a subtle enhancement in the release of one gliotransmitter, ATP, affects synaptic potentiation from an analysis of mice containing an astrocyte-selective (GFAP) mutation. We found that, relative to normal mice, weaker stimulation induced long-term potentiation (LTP) in mutant mice, indicating that the threshold to induce LTP was lowered in the mutant. While excitatory transmission was normal in the mutant, inhibitory GABAergic transmission was suppressed. We found that a low concentration of adenosine selectively attenuated inhibitory neuronal activity and lowered the threshold to induce LTP in wild type mice. In comparison, adenosine A(1) receptor antagonism reversed the lowered LTP threshold back to normal in the mutant mouse. We verified that adenosine levels in the cerebrospinal fluid of mutant mice were slightly elevated compared to wild type mice. This was apparently caused by an increase in ATP release from mutant astrocytes that could provide a source of augmented adenosine levels in the mutant. ATP is thought to suppress the excitability of neuronal circuits; however, a small increase in ATP release can result in a suppressed inhibitory tone and enhanced excitability of neuronal circuitry. These findings demonstrate that ATP released from astrocytes acts in a bidirectional fashion to regulate neuronal excitability depending on concentration.
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Fluoxetine-induced Cortical Adult Neurogenesis
Neuropsychopharmacology : Official Publication of the American College of Neuropsychopharmacology.
May, 2013 |
Pubmed ID: 23303069 Adult neurogenesis in the hippocampal subgranular zone (SGZ) and the anterior subventricular zone (SVZ) is regulated by multiple factors, including neurotransmitters, hormones, stress, aging, voluntary exercise, environmental enrichment, learning, and ischemia. Chronic treatment with selective serotonin reuptake inhibitors (SSRIs) modulates adult neurogenesis in the SGZ, the neuronal area that is hypothesized to mediate the antidepressant effects of these substances. Layer 1 inhibitory neuron progenitor cells (L1-INP cells) were recently identified in the adult cortex, but it remains unclear what factors other than ischemia affect the neurogenesis of L1-INP cells. Here, we show that chronic treatment with an SSRI, fluoxetine (FLX), stimulated the neurogenesis of γ-aminobutyric acid (GABA)ergic interneurons from L1-INP cells in the cortex of adult mice. Immunofluorescence and genetic analyses revealed that FLX treatment increased the number of L1-INP cells in all examined cortical regions in a dose-dependent manner. Furthermore, enhanced Venus reporter expression driven by the synapsin I promoter demonstrated that GABAergic interneurons were derived from retrovirally labeled L1-INP cells. In order to assess if these new GABAergic interneurons possess physiological function, we examined their effect on apoptosis surrounding areas following ischemia. Intriguingly, the number of neurons expressing the apoptotic marker, active caspase-3, was significantly lower in adult mice pretreated with FLX. Our findings indicate that FLX stimulates the neurogenesis of cortical GABAergic interneurons, which might have, at least, some functions, including a suppressive effect on apoptosis induced by ischemia.
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Deficiency of Schnurri-2, an MHC Enhancer Binding Protein, Induces Mild Chronic Inflammation in the Brain and Confers Molecular, Neuronal, and Behavioral Phenotypes Related to Schizophrenia
Neuropsychopharmacology : Official Publication of the American College of Neuropsychopharmacology.
Jul, 2013 |
Pubmed ID: 23389689 Schnurri-2 (Shn-2), an nuclear factor-κB site-binding protein, tightly binds to the enhancers of major histocompatibility complex class I genes and inflammatory cytokines, which have been shown to harbor common variant single-nucleotide polymorphisms associated with schizophrenia. Although genes related to immunity are implicated in schizophrenia, there has been no study showing that their mutation or knockout (KO) results in schizophrenia. Here, we show that Shn-2 KO mice have behavioral abnormalities that resemble those of schizophrenics. The mutant brain demonstrated multiple schizophrenia-related phenotypes, including transcriptome/proteome changes similar to those of postmortem schizophrenia patients, decreased parvalbumin and GAD67 levels, increased theta power on electroencephalograms, and a thinner cortex. Dentate gyrus granule cells failed to mature in mutants, a previously proposed endophenotype of schizophrenia. Shn-2 KO mice also exhibited mild chronic inflammation of the brain, as evidenced by increased inflammation markers (including GFAP and NADH/NADPH oxidase p22 phox), and genome-wide gene expression patterns similar to various inflammatory conditions. Chronic administration of anti-inflammatory drugs reduced hippocampal GFAP expression, and reversed deficits in working memory and nest-building behaviors in Shn-2 KO mice. These results suggest that genetically induced changes in immune system can be a predisposing factor in schizophrenia.
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The Immature Dentate Gyrus Represents a Shared Phenotype of Mouse Models of Epilepsy and Psychiatric Disease
Bipolar Disorders.
Jun, 2013 |
Pubmed ID: 23560889 There is accumulating evidence to suggest psychiatric disorders, such as bipolar disorder and schizophrenia, share common etiologies, pathophysiologies, genetics, and drug responses with many of the epilepsies. Here, we explored overlaps in cellular/molecular, electrophysiological, and behavioral phenotypes between putative mouse models of bipolar disorder/schizophrenia and epilepsy. We tested the hypothesis that an immature dentate gyrus (iDG), whose association with psychosis in patients has recently been reported, represents a common phenotype of both diseases.
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ENU-mutagenesis Mice with a Non-synonymous Mutation in Grin1 Exhibit Abnormal Anxiety-like Behaviors, Impaired Fear Memory, and Decreased Acoustic Startle Response
BMC Research Notes.
2013 |
Pubmed ID: 23688147 The Grin1 (glutamate receptor, ionotropic, NMDA1) gene expresses a subunit of N-methyl-D-aspartate (NMDA) receptors that is considered to play an important role in excitatory neurotransmission, synaptic plasticity, and brain development. Grin1 is a candidate susceptibility gene for neuropsychiatric disorders, including schizophrenia, bipolar disorder, and attention deficit/hyperactivity disorder (ADHD). In our previous study, we examined an N-ethyl-N-nitrosourea (ENU)-generated mutant mouse strain (Grin1(Rgsc174)/Grin1+) that has a non-synonymous mutation in Grin1. These mutant mice showed hyperactivity, increased novelty-seeking to objects, and abnormal social interactions. Therefore, Grin1(Rgsc174)/Grin1+ mice may serve as a potential animal model of neuropsychiatric disorders. However, other behavioral characteristics related to these disorders, such as working memory function and sensorimotor gating, have not been fully explored in these mutant mice. In this study, to further investigate the behavioral phenotypes of Grin1(Rgsc174)/Grin1+ mice, we subjected them to a comprehensive battery of behavioral tests.
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Immature Dentate Gyrus: an Endophenotype of Neuropsychiatric Disorders
Neural Plasticity.
2013 |
Pubmed ID: 23840971 Adequate maturation of neurons and their integration into the hippocampal circuit is crucial for normal cognitive function and emotional behavior, and disruption of this process could cause disturbances in mental health. Previous reports have shown that mice heterozygous for a null mutation in α -CaMKII, which encodes a key synaptic plasticity molecule, display abnormal behaviors related to schizophrenia and other psychiatric disorders. In these mutants, almost all neurons in the dentate gyrus are arrested at a pseudoimmature state at the molecular and electrophysiological levels, a phenomenon defined as "immature dentate gyrus (iDG)." To date, the iDG phenotype and shared behavioral abnormalities (including working memory deficit and hyperlocomotor activity) have been discovered in Schnurri-2 knockout, mutant SNAP-25 knock-in, and forebrain-specific calcineurin knockout mice. In addition, both chronic fluoxetine treatment and pilocarpine-induced seizures reverse the neuronal maturation, resulting in the iDG phenotype in wild-type mice. Importantly, an iDG-like phenomenon was observed in post-mortem analysis of brains from patients with schizophrenia/bipolar disorder. Based on these observations, we proposed that the iDG is a potential endophenotype shared by certain types of neuropsychiatric disorders. This review summarizes recent data describing this phenotype and discusses the data's potential implication in elucidating the pathophysiology of neuropsychiatric disorders.
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Point Mutation in Syntaxin-1A Causes Abnormal Vesicle Recycling, Behaviors, and Short Term Plasticity
The Journal of Biological Chemistry.
Nov, 2013 |
Pubmed ID: 24136198 Syntaxin-1A is a t-SNARE that is involved in vesicle docking and vesicle fusion; it is important in presynaptic exocytosis in neurons because it interacts with many regulatory proteins. Previously, we found the following: 1) that autophosphorylated Ca(2+)/calmodulin-dependent protein kinase II (CaMKII), an important modulator of neural plasticity, interacts with syntaxin-1A to regulate exocytosis, and 2) that a syntaxin missense mutation (R151G) attenuated this interaction. To determine more precisely the physiological importance of this interaction between CaMKII and syntaxin, we generated mice with a knock-in (KI) syntaxin-1A (R151G) mutation. Complexin is a molecular clamp involved in exocytosis, and in the KI mice, recruitment of complexin to the SNARE complex was reduced because of an abnormal CaMKII/syntaxin interaction. Nevertheless, SNARE complex formation was not inhibited, and consequently, basal neurotransmission was normal. However, the KI mice did exhibit more enhanced presynaptic plasticity than wild-type littermates; this enhanced plasticity could be associated with synaptic response than did wild-type littermates; this pronounced response included several behavioral abnormalities. Notably, the R151G phenotypes were generally similar to previously reported CaMKII mutant phenotypes. Additionally, synaptic recycling in these KI mice was delayed, and the density of synaptic vesicles was reduced. Taken together, our results indicated that this single point mutation in syntaxin-1A causes abnormal regulation of neuronal plasticity and vesicle recycling and that the affected syntaxin-1A/CaMKII interaction is essential for normal brain and synaptic functions in vivo.
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In Vivo Evaluation of Cellular Activity in αCaMKII Heterozygous Knockout Mice Using Manganese-enhanced Magnetic Resonance Imaging (MEMRI)
Frontiers in Integrative Neuroscience.
2013 |
Pubmed ID: 24273499 The alpha-calcium/calmodulin-dependent protein kinase II (αCaMKII) is a serine/threonine protein kinase predominantly expressed in the forebrain, especially in the postsynaptic density, and plays a key role in synaptic plasticity, learning and memory. αCaMKII heterozygous knockout (HKO) mice exhibit abnormal emotional and aggressive behaviors and cognitive impairments and have been proposed as an animal model of psychiatric illness. Our previous studies have shown that the expression of immediate early genes (IEGs) after exposure to electric foot shock or after performing a working memory task is decreased in the hippocampus, central amygdala, and medial prefrontal cortex of mutant mice. These changes could be caused by disturbances in neuronal signal transduction; however, it is still unclear whether neuronal activity is reduced in these regions. In this study, we performed in vivo manganese-enhanced magnetic resonance imaging (MEMRI) to assess the regional cellular activity in the brains of αCaMKII HKO mice. The signal intensity of MEMRI 24 h after systemic MnCl2 administration reflects functional increases of Mn(2+) influx into neurons and glia via transport mechanisms, such as voltage-gated and/or ligand-gated Ca(2+) channels. αCaMKII HKO mice demonstrated a low signal intensity of MEMRI in the dentate gyrus (DG), in which almost all neurons were at immature status at the molecular, morphological, and electrophysiological levels. In contrast, analysis of the signal intensity in these mutant mice revealed increased activity in the CA1 area of the hippocampus, a region crucial for cognitive function. The signal intensity was also increased in the bed nucleus of the stria terminalis (BNST), which is involved in anxiety. These changes in the mutant mice may be responsible for the observed dysregulated behaviors, such as cognitive deficit and abnormal anxiety-like behavior, which are similar to symptoms seen in human psychiatric disorders.
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PRICKLE1 Interaction with SYNAPSIN I Reveals a Role in Autism Spectrum Disorders
PloS One.
2013 |
Pubmed ID: 24312498 The frequent comorbidity of Autism Spectrum Disorders (ASDs) with epilepsy suggests a shared underlying genetic susceptibility; several genes, when mutated, can contribute to both disorders. Recently, PRICKLE1 missense mutations were found to segregate with ASD. However, the mechanism by which mutations in this gene might contribute to ASD is unknown. To elucidate the role of PRICKLE1 in ASDs, we carried out studies in Prickle1(+/-) mice and Drosophila, yeast, and neuronal cell lines. We show that mice with Prickle1 mutations exhibit ASD-like behaviors. To find proteins that interact with PRICKLE1 in the central nervous system, we performed a yeast two-hybrid screen with a human brain cDNA library and isolated a peptide with homology to SYNAPSIN I (SYN1), a protein involved in synaptogenesis, synaptic vesicle formation, and regulation of neurotransmitter release. Endogenous Prickle1 and Syn1 co-localize in neurons and physically interact via the SYN1 region mutated in ASD and epilepsy. Finally, a mutation in PRICKLE1 disrupts its ability to increase the size of dense-core vesicles in PC12 cells. Taken together, these findings suggest PRICKLE1 mutations contribute to ASD by disrupting the interaction with SYN1 and regulation of synaptic vesicles.
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Increased Behavioral and Neuronal Responses to a Hallucinogenic Drug in PACAP Heterozygous Mutant Mice
PloS One.
2014 |
Pubmed ID: 24586556 Accumulating evidence from human genetic studies implicates the pituitary adenylate cyclase-activating polypeptide (PACAP) gene as a risk factor for psychiatric disorders, including schizophrenia and stress-related diseases. Mice with homozygous disruption of the PACAP gene display profound behavioral and neurological abnormalities that are ameliorated with the atypical antipsychotic and dopamine D2 and serotonin (5-HT)2 antagonist risperidone and the 5-HT2 receptor antagonist ritanserin; however, the underlying mechanisms remain unknown. Here, we investigated if PACAP heterozygous mutant (PACAP(+/-)) mice, which appear behaviorally normal, are vulnerable to aversive stimuli. PACAP(+/-) mice were administered a 5-HT2 receptor agonist, (±)-2,5-dimethoxy-4-iodoamphetamine (DOI), a hallucinogenic drug, and their responses were compared with the littermate wild-type mice. After DOI injection, PACAP(+/-) mice showed increased head-twitch responses, while their behavior was normal after saline. DOI induced deficits in sensorimotor gating, as determined by prepulse inhibition, specifically in PACAP(+/-) mice. However, other 5-HT2 receptor-dependent responses, such as corticosterone release and hypothermia, were similarly observed in PACAP(+/-) and wild-type mice. c-Fos expression analysis, performed in various brain regions, revealed that the DOI-induced increase in the number of c-Fos-positive cells was more pronounced in 5-HT2A receptor-negative cells in the somatosensory cortex in PACAP(+/-) mice compared with wild-type mice. These results indicate that PACAP(+/-) mice exhibit specific vulnerability to DOI-induced deficits in cortical sensory function, such as exaggerated head-twitch responses and sensorimotor gating deficits. Our findings provide insight into the neural mechanisms underlying impaired behavioral responses in which 5-HT2 receptors are implicated.
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Comprehensive Behavioral Analysis of Cluster of Differentiation 47 Knockout Mice
PloS One.
2014 |
Pubmed ID: 24586890 Cluster of differentiation 47 (CD47) is a member of the immunoglobulin superfamily which functions as a ligand for the extracellular region of signal regulatory protein α (SIRPα), a protein which is abundantly expressed in the brain. Previous studies, including ours, have demonstrated that both CD47 and SIRPα fulfill various functions in the central nervous system (CNS), such as the modulation of synaptic transmission and neuronal cell survival. We previously reported that CD47 is involved in the regulation of depression-like behavior of mice in the forced swim test through its modulation of tyrosine phosphorylation of SIRPα. However, other potential behavioral functions of CD47 remain largely unknown. In this study, in an effort to further investigate functional roles of CD47 in the CNS, CD47 knockout (KO) mice and their wild-type littermates were subjected to a battery of behavioral tests. CD47 KO mice displayed decreased prepulse inhibition, while the startle response did not differ between genotypes. The mutants exhibited slightly but significantly decreased sociability and social novelty preference in Crawley's three-chamber social approach test, whereas in social interaction tests in which experimental and stimulus mice have direct contact with each other in a freely moving setting in a novel environment or home cage, there were no significant differences between the genotypes. While previous studies suggested that CD47 regulates fear memory in the inhibitory avoidance test in rodents, our CD47 KO mice exhibited normal fear and spatial memory in the fear conditioning and the Barnes maze tests, respectively. These findings suggest that CD47 is potentially involved in the regulation of sensorimotor gating and social behavior in mice.
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Hippocampal Neurogenesis Regulates Forgetting During Adulthood and Infancy
Science (New York, N.Y.).
May, 2014 |
Pubmed ID: 24812394 Throughout life, new neurons are continuously added to the dentate gyrus. As this continuous addition remodels hippocampal circuits, computational models predict that neurogenesis leads to degradation or forgetting of established memories. Consistent with this, increasing neurogenesis after the formation of a memory was sufficient to induce forgetting in adult mice. By contrast, during infancy, when hippocampal neurogenesis levels are high and freshly generated memories tend to be rapidly forgotten (infantile amnesia), decreasing neurogenesis after memory formation mitigated forgetting. In precocial species, including guinea pigs and degus, most granule cells are generated prenatally. Consistent with reduced levels of postnatal hippocampal neurogenesis, infant guinea pigs and degus did not exhibit forgetting. However, increasing neurogenesis after memory formation induced infantile amnesia in these species.
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[Immaturity of Brain As an Endophenotype of Neuropsychiatric Disorders]
Nihon Shinkei Seishin Yakurigaku Zasshi = Japanese Journal of Psychopharmacology.
Jun, 2014 |
Pubmed ID: 25076776 Schizophrenia and bipolar disorder are severe neuropsychiatric disorders, affecting about 1% of the population. Identifying endophenotypes in the brains of neuropsychiatric patients is now considered the way to understand the underlying mechanisms and to improve therapeutic outcomes. However, the endophenotypes and brain mechanisms of the disorders remain unknown. We have previously reported that alpha-CaMKII heterozygous knockout mice show abnormal behaviors related to neuropsychiatric disorders. In these mutant mice, almost all neurons in the hippocampal dentate gyrus stay at a pseudo-immature state, which we refer to as "immature dentate gyrus (iDG)." So far, the iDG phenotype and similar behavioral abnormalities have been found in Schnurri-2 knockout, SNAP-25 mutant, and forebrain-specific calcineurin knockout mice. In addition, we found that both chronic fluoxetine treatment and pilocarpine-induced seizures can reverse the maturation state of the mature neurons, resulting in the iDG phenotype in wild-type mice. Such an iDG-like phenomenon was observed in the post-mortem brains from patients with schizophrenia/bipolar disorder. Recent studies suggest that cortex and amygdala of schizophrenia patients are also at a pseudo-immature state. Based on the findings, we proposed that immaturity of certain types of cells in the brain is a potential endophenotype of neuropsychiatric disorders.
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