Alcohol and cerebellar circuits

描述（由申请人提供）：急性和长期的乙醇（EtOH）暴露会产生小脑功能障碍，导致步态、平衡和协调的改变，这是美国大量伤害和死亡的原因。最近的证据表明，EtOH影响执行功能，这可能是额小脑回路中断的结果。然而，我们对EtOH在小脑中的作用机制的理解仍处于起步阶段。来自脑干和脊髓的兴奋性输入经苔藓纤维通过颗粒细胞进入小脑皮层。这些神经元也接受来自高尔基细胞的抑制性输入，高尔基细胞是主要的颗粒细胞层神经元间亚型。高尔基细胞依次接受苔藓纤维的前馈兴奋输入、颗粒细胞轴突的反馈兴奋输入和分子层中间神经元的抑制性兴奋输入。我们的总体假设是，急性EtOH暴露通过降低颗粒细胞和高尔基细胞的谷氨酸能和增加gaba能传递来损害颗粒层电路的正常功能。具体目的1是表征EtOH对颗粒细胞中谷氨酸能传递的影响。在之前的资助期内，我们确定EtOH增加了颗粒细胞的强直性和阶段性gaba能输入，而不影响AMPA受体介导的自发谷氨酸能传递。利用急性小脑切片制备和膜片钳电生理技术，我们将研究EtOH对苔藓状纤维-颗粒细胞突触NMDA受体功能和长期增强的影响。我们将通过苔藓纤维激活的感觉样模式来研究其对颗粒细胞激活的影响；在这些研究中，单个神经元的记录将由[苔藓纤维激活区域]的自身荧光光学成像来补充。具体目标#2是进一步表征EtOH对高尔基细胞的影响。在之前的资助期间，我们证明了EtOH增加高尔基细胞放电，并提出了表征这种效应的机制。[基于计算机模拟和实验研究的结合，我们提出表征IA， Na+/K+泵和持续Na+电流作为EtOH效应的潜在介质]。我们还将研究EtOH对高尔基细胞gaba能和/或谷氨酸能输入的影响。这些急性切片的研究将与EtOH对这些神经元功能的急性影响的体内电生理实验相补充。在具体目标#3中，我们将使用数据驱动的计算神经科学方法研究EtOH对颗粒细胞层整体网络活动的影响。这些多学科的研究将大大增加我们对EtOH对小脑颗粒细胞层的急性作用的理解，为确定针对EtOH诱导的小脑功能障碍的治疗干预的新靶点奠定基础。

DESCRIPTION (provided by applicant): Acute and long-term ethanol (EtOH) exposure produces cerebellar dysfunction, leading to alterations in gait, balance and coordination that are responsible for a large number of injuries and deaths in the United States. Recent evidence indicates that EtOH affects executive functions and this could be a consequence of disruptions in frontocerebellar circuitry. However, our understanding of the mechanism of action of EtOH in the cerebellum is still in its infancy. Excitatory input from the brain stem and spinal cord enters the cerebellar cortex at the granule cells via the mossy fibers. These neurons also receive inhibitory input from the Golgi cells, which are the major granule cell layer interneuronal subtype. Golgi cells, in turn, receive feedforward excitatory input from mossy fibers, feedback excitatory input from granule cell axons and inhibitory input from molecular layer interneurons. Our overarching hypothesis is that acute EtOH exposure impairs the normal functioning of granule layer circuitry by decreasing glutamatergic and increasing GABAergic transmission at both granule and Golgi cells. Specific Aim #1 is to characterize the effect of EtOH on glutamatergic transmission at granule cells. During the previous funding period, we determined that EtOH increases tonic and phasic GABAergic input to granule cells without affecting spontaneous glutamatergic transmission mediated by AMPA receptors. Using the acute cerebellar slice preparation and patch-clamp electrophysiological techniques, we will now study the effect of EtOH on NMDA receptor function and long- term potentiation at mossy fiber-to-granule cell synapses. We will investigate its effects on granule cell activation by sensory-like patters of mossy fiber activation; for these studies, single-neuron recordings will be complemented by autofluorescence optical imaging of [the mossy fiber area of activation]. Specific Aim #2 is to further characterize the effects of EtOH on Golgi cells. During the previous funding period, we demonstrated that EtOH increases Golgi cell firing and propose to characterize the mechanism responsible for this effect. [Based on a combination of computer modeling and experimental studies, we propose to characterize IA, Na+/K+ pump and persistent Na+ currents as potential mediators of EtOH's effect]. We will also investigate EtOH's effect on GABAergic and/or glutamatergic input to Golgi cells. These studies with acute slices will be complemented with in vivo electrophysiological experiments of the acute effects of EtOH on the function of these neurons. In Specific Aim #3, we will investigate the effect of EtOH on network activity in the granule cell layer as a whole using a data-driven computational neuroscience approach. These multidisciplinary studies will significantly increase our understanding of the acute effects of EtOH on the cerebellar granule cell layer, forming the basis for the identification of new targets for therapeutic interventions against EtOH-induced cerebellar dysfunction. PUBLIC HEALTH RELEVANCE: The cerebellum is a portion of the brain that controls gait, balance, coordination and certain internal mental processes such as attention and planning. Ingestion of alcohol profoundly affects normal cerebellar functioning and our understanding of the mechanisms responsible for these effects of alcohol is very limited. The goal of this project is to characterize the effect of alcohol on communication between cerebellar neurons, forming the basis for the development of novel treatments that may aid in the recovery of alcoholic patients.