L-3-n-butylphthalide (L-NBP), an extract from seeds of Apium graveolens Linn (Chinese celery), has been shown to have neuroprotective effects on cerebral ischemic, vascular dementia and amyloid-beta (Abeta)-induced animal models by inhibiting oxidative injury, neuronal apoptosis and glial activation, regulating amyloid-beta protein precursor (AbetaPP) processing and reducing Abeta generation. The objective of this study was to investigate the effects of L-3-n-butylphthalide on memory impairment and the expression of brain neurotrophic derived factor (BNDF), kinaseB (TrkB), phosphatidylinositol 3 kinase (PI3K) and Akt in APP/PS1 double transgenic mouse models. APP/PS1 double transgenic mice were administered 30 mg/kg•d L-NBP and 10 mg/kg•d L-NBP for one month. The learning and memory ability were studied using the water maze test. Protein expression and transcript levels of genes in the mice hippocampus were evaluated using western blot and quantitative reverse transcription-polymerase chain reaction (qRT-PCR), respectively. The results demonstrated that both 30 mg/kg•d L-NBP and 10 mg/kg•d L-NBP doses of L-NBP significantly increased memory capability and the expression of hippocampal BDNF/TrkB/PI3K/AKT in mice The results suggested that L-NBP treatment may reverse memory impairment in APP/PS1 transgenic mice, and BDNF/TrkB/PI3K/AKT, may be involved in this process.
Alzheimers disease (AD) is pathologically characterized by deposition of ?-amyloid (A?) peptides, which closely correlates with the balance of nerve growth factor (NGF)-related TrkA/p75(NTR) signaling. (-)-Epigallocatechin-3-gallate (EGCG) is used for prevention and treatment of many neurodegenerative diseases, including AD. However, whether the neuroprotective effects of EGCG treatment were via modulating the balance of TrkA/p75(NTR) signaling was still unknown. In this study, we found that EGCG treatment (2 mg · kg (-1) · day (-1)) dramatically ameliorated the cognitive impairments, reduced the overexpressions of A?(1-40) and amyloid precursor protein (APP), and inhibited the neuronal apoptosis in the APP/PS1 mice. Interestingly, the EGCG treatment enhanced the relative expression level of NGF by increasing the NGF/proNGF ratio in the APP/PS1 mice. Moreover, after EGCG treatment, TrkA signaling was activated by increasing the phosphorylation of TrkA following the increased phosphorylation of c-Raf, ERK1/2, and cAMP response element-binding protein (CREB), simultaneously the p75(NTR) signaling was significantly inhibited by decreasing the p75(ICD) expression, JNK2 phosphorylation, and cleaved-caspase 3 expression, so that the A? deposits and neuronal apoptosis in the hippocampus were inhibited.
Salient cues can prompt the rapid interruption of planned actions. It has been proposed that fast, reactive behavioral inhibition involves specific basal ganglia pathways, and we tested this by comparing activity in multiple rat basal ganglia structures during performance of a stop-signal task. Subthalamic nucleus (STN) neurons exhibited low-latency responses to Stop cues, irrespective of whether actions were canceled or not. By contrast, neurons downstream in the substantia nigra pars reticulata (SNr) only responded to Stop cues in trials with successful cancellation. Recordings and simulations together indicate that this sensorimotor gating arises from the relative timing of two distinct inputs to neurons in the SNr dorsolateral core subregion: cue-related excitation from STN and movement-related inhibition from striatum. Our results support race models of action cancellation, with stopping requiring Stop-cue information to be transmitted from STN to SNr before increased striatal input creates a point of no return.
Emerging evidence suggests that synaptic dysfunction occurs prior to neuronal loss in neurodegenerative diseases, such as amyotrophic lateral sclerosis (ALS). Therefore, monitoring synaptic activity during early stages of neurodegeneration may provide valuable information for the development of diagnostic and/or therapeutic strategies. Here, we describe an electrophysiological method routinely applied in our laboratory for investigating synaptic activity of the neuromuscular junction (NMJ), the synaptic connection between motoneurons and skeletal muscles. Using conventional intracellular sharp electrodes, both spontaneous synaptic activity (miniature end-plate potentials) and evoked synaptic activity (end-plate potentials) can be readily recorded in acutely isolated nerve-muscle preparations. This method can also be adapted to various simulation protocols for studying short-term plasticity of neuromuscular synapses.
Developing skeletal myofibers in vertebrates are intrinsically pre-patterned for motor nerve innervation. However, the intrinsic factors that regulate muscle pre-patterning remain unknown. We found that a functional skeletal muscle dihydropyridine receptor (DHPR, the L-type Ca(2+) channel in muscle) was required for muscle pre-patterning during the development of the neuromuscular junction (NMJ). Targeted deletion of the ?1 subunit of DHPR (Cacnb1) in mice led to muscle pre-patterning defects, aberrant innervation and precocious maturation of the NMJ. Reintroducing Cacnb1 into Cacnb1(-/-) muscles reversed the pre-patterning defects and restored normal development of the NMJ. The mechanism by which DHPRs govern muscle pre-patterning is independent of their role in excitation-contraction coupling, but requires Ca(2+) influx through the L-type Ca(2+) channel. Our findings indicate that the skeletal muscle DHPR retrogradely regulates the patterning and formation of the NMJ.
The enzyme ubiquitin carboxyl-terminal hydrolase L1 (UCH-L1) is one of the most abundant proteins in the mammalian nervous system. In humans, UCH-L1 is also found in the ubiquitinated inclusion bodies that characterize neurodegenerative diseases in the brain, suggesting its involvement in neurodegeneration. The physiologic role of UCH-L1 in neurons, however, remains to be further elucidated. For example, previous studies have provided evidence both for and against the role of UCH-L1 in synaptic function in the brain. Here, we have characterized a line of knockout mice deficient in the UCH-L1 gene. We found that, in the absence of UCH-L1, synaptic transmission at the neuromuscular junctions (NMJs) is markedly impaired. Both spontaneous and evoked synaptic activity are reduced; paired pulse-facilitation is impaired, and synaptic transmission fails to respond to high-frequency, repetitive stimulation at the NMJs of UCH-L1 knockout mice. Morphologic analyses of the NMJs further revealed profound structural defects-loss of synaptic vesicles and accumulation of tubulovesicular structures at the presynaptic nerve terminals, and denervation of the muscles in UCH-L1 knockout mice. These findings demonstrate that UCH-L1 is required for the maintenance of the structure and function of the NMJ and that the loss of normal UCH-L1 activity may result in neurodegeneration in the peripheral nervous system.
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