Alcohol and cerebellar circuits

描述（由申请人提供）：浓度大于或等于0.08 g/dl的乙醇会显著损害运动技能，这种影响是美国大多数交通事故相关死亡的原因。重要的是，对乙醇的这种作用不敏感的人更有可能患上酒精中毒。此外，慢性酒精中毒和胎儿酒精综合征与小脑神经元数量的显著减少有关。因此，了解乙醇在小脑中的作用机制是一个非常有趣的领域。小脑皮层的神经元在运动功能的控制中起着核心作用。这些神经元形成一个基本的回路单元，浦肯野神经元是这个回路的主要输出。浦肯野神经元通过苔藓纤维接收来自脊髓和脑干的兴奋性输入，通过攀爬纤维接收来自下橄榄的兴奋性输入。这些神经元也接受来自分子层中间神经元的抑制性输入。苔藓纤维的兴奋性输入通过小脑颗粒细胞传递给浦肯野神经元，这些细胞受高尔基中间神经元的抑制控制。初步数据表明，急性乙醇暴露增加高尔基神经元间-颗粒细胞突触和分子层神经元间-浦肯野神经元突触的gaba能张力。此外，它还抑制纤维-浦肯野神经元突触的兴奋性输入。我们假设乙醇通过突触前调节基本回路单元内主要突触的神经递质释放来抑制成熟小脑皮层的突触传递。我们建议使用急性小脑切片制备和膜片钳电生理技术来验证这一假设。具体目的1是研究乙醇对颗粒细胞层神经元的急性作用。我们将评估乙醇对gaba能在颗粒细胞传递的影响及其对这些细胞兴奋性的影响。我们还将评估乙醇对高尔基细胞兴奋性的影响。具体目标2是研究乙醇对浦肯野神经元和分子层的急性影响。我们将测量乙醇在苔藓纤维颗粒细胞通路或平行纤维通路刺激下对浦肯野细胞放电的影响。我们将评估乙醇对分子层神经元间-浦肯野细胞突触动作电位非依赖性GABA释放诱发mIPSCs频率的影响。

DESCRIPTION (provided by applicant): Ethanol at concentrations greater than or qual too 0.08 g/dl significantly impairs motor skills and this effect is responsible for the majority of traffic accident-related deaths in the United States. Importantly, individuals with low sensitivity to this action of ethanol are more likely to develop alcoholism. In addition, chronic alcoholism and fetal alcohol syndrome are associated with significant decreases in the number of cerebellar neurons. Therefore, understanding the mechanism of action of ethanol in the cerebellum is an area of tremendous interest. Neurons of the cerebellar cortex play a central role in the control of motor functions. These neurons form a basic circuit unit and Purkinje neurons are the main output of this circuit. Purkinje neurons receive excitatory inputs from the spinal cord and brain stem via mossy fibers and from the inferior olive via climbing fibers. These neurons also receive inhibitory input from molecular layer interneurons. Excitatory input from the mossy fibers is relayed to Purkinje neurons by the cerebellar granule cells and these cells are under the inhibitory control of Golgi interneurons. Preliminary data indicate that acute ethanol exposure increases GABAergic tone at Golgi interneuron-to-granule cell synapses and at molecular layer interneuron-to-Purkinje neuron synapses. Moreover, it also inhibits excitatory input at climbing fiber-to-Purkinje neuron synapses. We hypothesize that ethanol depresses synaptic transmission in the mature cerebellar cortex by presynaptically modulating neurotransmitter release at major synapses within the basic circuit unit. We propose to use the acute cerebellar slice preparation and patch-clamp electrophysiological techniques to test this hypothesis. Specific Aim #1 is to investigate the acute effect of ethanol on neurons of the granule cell layer. We will assess the effect of ethanol on GABAergic transmission at granule cells and its impact on the excitability of these cells. We will also evaluate the effects of ethanol on Golgi cell excitability. Specific Aim #2 is to investigate the acute effects of ethanol on neurons of the Purkinje and molecular layers. We will measure the effects of ethanol on Purkinje cell firing in response to stimulation of the mossy fiber granule cell pathway or the parallel fiber pathway. We will assess the effect of ethanol on the frequency of mIPSCs evoked by action potential-independent GABA release at molecular layer interneuron-to-Purkinje cell synapses. Finally, we will evaluate the mechanism by which ethanol affects the complex spike evoked in Purkinje cells by stimulation of climbing fibers. Together, these experiments will provide a comprehensive view of the acute effects of ethanol on mature cerebellar synapses of the cerebellar cortex. This type of comprehensive study has not been performed before and it will significantly increase our understanding of the mechanism of action of ethanol in the central nervous system.