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In JoVE (1)
Other Publications (5)
- Experimental Brain Research. Experimentelle Hirnforschung. Expérimentation Cérébrale
- Alcohol (Fayetteville, N.Y.)
- BMC Neuroscience
- Chemical Senses
- Archives of Facial Plastic Surgery : Official Publication for the American Academy of Facial Plastic and Reconstructive Surgery, Inc. and the International Federation of Facial Plastic Surgery Societies
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Articles by Taha A. Jan in JoVE
JoVE Neuroscience
Isolera LacZ-uttryckande celler från mus Inre öronvävnader med flödescytometri
Department of Otolaryngology-Head and Neck Surgery, Stanford University School of Medicine
Other articles by Taha A. Jan on PubMed
Prenatal Alcohol Exposure (PAE) Reduces the Size of the Forepaw Representation in Forepaw Barrel Subfield (FBS) Cortex in Neonatal Rats: Relationship Between Periphery and Central Representation
Prenatal alcohol exposure (PAE) alters limb development that may lead to structural and functional abnormalities of the limb reported in children diagnosed with Fetal Alcohol Spectrum Disorder. To determine whether PAE alters the central representation of the forelimb we used the rodent barrel cortex as our model system where it was possible to visualize and quantitatively measure the size of the forepaw representation in the forepaw barrel subfield (FBS) in first somatosensory cortex. In the present study, we examined the effects of PAE on pattern and size of the forepaw and forepaw representation in FBS in neonatal rats at gestational day 32 that corresponds to postnatal day 9. Pregnant Sprague-Dawley rats were chronically intubated with binge doses of ethanol (6 g/kg) from gestational day 1 through gestational day 20. The offspring of the ethanol treated dams comprised the ethanol (EtOH) group. The effect of PAE on the EtOH group was compared with a nutritional-controlled pairfed (PF) group and a normal chowfed (CF) group. The ventral (glabrous) surface area of the forepaw digits, length of digit 2 through digit 5, and the corresponding glabrous forepaw digit representations in the FBS were measured and compared between treatment groups. In rats exposed to in utero alcohol, the sizes of the overall glabrous forepaw and forepaw digits were significantly reduced in EtOH pups compared to CF and PF pups; overall glabrous forepaw area was 11% smaller than CF controls. Glabrous digit lengths were also smaller in EtOH rats compared to CF controls and significantly smaller in digit 2 through digit 4. The glabrous digit representation in FBS was 18% smaller in the EtOH group when compared to the CF treatment. However, PAE did not produce malformations in the forepaw or alter the pattern of the forepaw representation in FBS; instead, PAE significantly reduced both body and brain weights compared to controls. Unexpectedly, little or no correlation was observed between the size of the glabrous forepaw compared to the size of the glabrous forepaw representation in the FBS for any of the treatment groups. The present findings of PAE-related alterations in sensory periphery and the central cortical representation may underlie deficits in sensorimotor integration reported among children with Fetal Alcohol Spectrum Disorder.
Early Postnatal Alcohol Exposure Reduced the Size of Vibrissal Barrel Field in Rat Somatosensory Cortex (SI) but Did Not Disrupt Barrel Field Organization
Prenatal alcohol exposure (PAE) has been shown to alter the somatosensory cortex in both human and animal studies. In rodents, PAE reduced the size, but not the pattern of the posteromedial barrel subfield (PMBSF) associated with the representation of the whiskers, in newborn, juvenile, and adult rats. However, the PMBSF is not present at birth, but rather first appears in the middle of the first postnatal week during the brain-growth spurt period. These findings raise questions whether early postnatal alcohol exposure might disrupt both barrel field pattern and size, questions that were investigated in the present study. Newborn Sprague-Dawley rats were assigned into alcohol (Alc), nutritional gastric control (GC), and suckle control (SC) groups on postnatal day 4 (P4). Rat pups in Alc and GC were artificially fed with alcohol and maltose-dextrin dissolved in milk, respectively, via an implant gastrostomy tube, from P4 to P9. Pups in the Alc group received alcohol (6.0 g/kg) in milk, while the GC controls received isocaloric equivalent maltose-dextrin dissolved in milk. Pups in the SC group remained with their mothers and breast fed throughout the experimental period. On P10, pups in each group were weighed, sacrificed, and their brains removed and weighed. Cortical hemispheres were separated, weighed, flattened, sectioned tangentially, stained with cytochrome oxidase, and PMBSF measured. The sizes of barrels and the interbarrel septal region within PMBSF, as well as body and brain weights were compared between the three groups. The sizes of PMSBF barrel and septal areas were significantly smaller (P<.01) in Alc group compared to controls, while the PMBSF barrel pattern remained unaltered. Body, whole-brain, forebrain, and hemisphere weights were significantly reduced (P<.01) in Alc pups compared to control groups. GC and SC groups did not differ significantly in all dependent variables, except body weight at P9 and P10 (P<.01). These results suggest that postnatal alcohol exposure, like prenatal exposure, significantly influenced the size of the barrel field, but not barrel field pattern formation, indicating that barrel field pattern formation consolidated prior to P4. These results are important for understanding sensorimotor deficits reported in children suffering from fetal alcohol spectrum disorder (FASD).
Genetic Analysis of Posterior Medial Barrel Subfield (PMBSF) Size in Somatosensory Cortex (SI) in Recombinant Inbred Strains of Mice
Quantitative trait locus (QTL) mapping is an important tool for identifying potential candidate genes linked to complex traits. QTL mapping has been used to identify genes associated with cytoarchitecture, cell number, brain size, and brain volume. Previously, QTL mapping was utilized to examine variation of barrel field size in the somatosensory cortex in a limited number of recombinant inbred (RI) strains of mice. In order to further elucidate the underlying natural variation in mouse primary somatosensory cortex, we measured the size of the posterior medial barrel subfield (PMBSF), associated with the representation of the large mystacial vibrissae, in an expanded sample set that included 42 BXD RI strains, two parental strains (C57BL/6J and DBA/2J), and one F1 strain (B6D2F1). Cytochrome oxidase labeling was used to visualize barrels within the PMBSF.
Genetic Analysis of Tongue Size and Taste Papillae Number and Size in Recombinant Inbred Strains of Mice
Quantitative trait loci (QTLs) analysis has been used to examine natural variation of phenotypes in the mouse somatosensory cortex, hippocampus, cerebellum, and amygdala. QTL analysis has also been utilized to map and identify genes underlying anatomical features such as muscle, organ, and body weights. However, this methodology has not been previously applied to identification of anatomical structures related to gustatory phenotypes. In this study, we used QTL analysis to map and characterize genes underlying tongue size, papillae number, and papillae area. In a set of 43 BXD recombinant inbred (RI) mice (n = 111) and 2 parental strains (C57BL/6J and DBA/2J; n = 7), we measured tongue length, width, and weight. In a subset of 23 BXD RI mice and the parental mice, we measured filiform and fungiform papillae number and fungiform papillae area. Using QTL linkage analysis (through WebQTL), we detected 2 significant and noninteracting QTLs influencing tongue length on chromosomes 5 and 7. We also found a significant QTL on chromosome 19 underlying fungiform papillae area and a suggestive QTL on chromosome 2 linked to fungiform papillae number. From these QTLs, we identified a number of candidate genes within the QTL intervals that include SRY-box containing gene, nebulin-related anchoring protein, and actin-binding LIM protein 1. This study is an important first step in identifying genetic factors underlying tongue size, papillae size, and papillae number using QTL analysis.
Effects of Corticosteroids on Functional Recovery and Neuron Survival After Facial Nerve Injury in Mice
To assess the effects of corticosteroid administration on functional recovery and cell survival in the facial motor nucleus (FMN) following crush injury in adult and juvenile mice and to evaluate the relationship between functional recovery and facial motoneuron survival.
