Ethanol and the Developing Cerebellum

描述(申请人提供)：发育性酒精暴露，涉及出生后4-6天(PN4-6)，是人类在妊娠早期暴露的模型，导致小脑浦肯野神经元丧失，运动技能和眨眼适应功能障碍。在人类FASD中也发现了类似的损害。下橄榄突触的攀爬纤维位于浦肯野细胞上，是正常功能的不可或缺的组成部分。很少有涉及酒精暴露的研究集中在攀爬纤维的作用上。我们假设，出生后早期(发育)阶段的酒精暴露通过改变浦肯野细胞与攀升纤维的突触连接而对小脑中幸存的神经元成分产生负面影响，而不影响神经元的丢失。我们还推测，乙醇诱导的特定类别的谷氨酸受体的变化在机制上参与了这些变化。我们将利用共聚焦显微镜来检查这些神经元结构的三维形态，以及随着它们的发育和成熟，乙醇诱导的变化的程度。我们提出了以下具体目标：(1)建立在出生后酒精暴露后攀爬纤维发生改变，而不是浦肯野神经元丢失的情况。我们将在PN4、PN4 6和PN7 9上使用乙醇处理的大鼠。浦肯野神经元只在PN4-6窗口对酒精暴露敏感。(2)观察出生后酒精暴露对蒲肯野细胞形态发育的影响。我们将描述与对照组相比，在接受不同发育暴露的大鼠中，存活的浦肯野细胞的胞体和树突树的形态发展。这项深入的分析将为这些幸存的浦肯野神经元提供第一批这样的数据。(3)确定谷氨酸受体亚型AMPA和mGluR是否是乙醇引起的爬行纤维发育改变的原因。我们将通过给予谷氨酸受体阻滞剂同时或不同时给予酒精暴露来探索谷氨酸受体和攀升纤维发育连接之间的机制联系。我们认为，乙醇作用的一个重要组成部分是通过在关键发育时期阻断这些受体而起作用的。我们的重点是小脑结构的现状和持续发展，这些结构在狂欢的乙醇损伤中幸存下来，而此时已知会导致显著的神经元死亡。这项工作的最终目标是从这些知识中得出一种手段或方法，以最大限度地利用这些剩余结构，为个人提供最佳结果。由于任何治疗干预都不能取代丢失的浦肯野细胞，因此了解攀升纤维和幸存的浦肯野神经元之间复杂联系变化的特征和本质有望改善患有FASD的儿童的治疗。

DESCRIPTION (provided by applicant): Developmental ethanol exposure, involving postnatal days 4-6 (PN4-6) in rats, is a model of human exposure during the early third trimester and results in loss of Purkinje neurons of the cerebellum and functional deficits in motor skills and eye blink conditioning. Similar impairments are seen in human FASD. Climbing fibers from the inferior olive synapse on Purkinje cells and are an integral component for proper functioning. Few studies involving ethanol exposure have focused on the role of climbing fibers. We hypothesize that ethanol exposure in the early postnatal (developmental) stage negatively impacts the surviving neuronal components of the cerebellum by altering synaptic connections of the Purkinje cells to climbing fibers, independent of neuronal loss. We also theorize that ethanol-induced alterations in specific classes of glutamate receptors are mechanistically involved in these changes. We will utilize confocal microscopy to examine the 3-D morphology of these neuronal structures and the extent of ethanol-induced alterations, as they develop and mature. We propose the following Specific Aims: (1) Establish that climbing fibers are altered following postnatal ethanol exposure independent of Purkinje neuron loss. We will use rats treated with ethanol on PN4, PN4 6, and PN7 9. Purkinje neurons are vulnerable to ethanol exposure only during the PN4-6 window. (2) Evaluate the morphological development of Purkinje cells that survive postnatal ethanol exposure. We will characterize the morphological development of the soma and the dendritic tree of the surviving Purkinje cells in groups of rats receiving varying developmental exposures to ethanol compared to a control group. This in-depth analysis will provide the first such data for these surviving Purkinje neurons. (3) Determine whether the glutamate receptor subtypes, AMPA and mGluR, are causal mechanisms of ethanol-induced alterations of climbing fiber development. We will explore the mechanistic link between glutamate receptors and climbing fiber developmental connections by administering glutamate receptor blockers with and without concurrent ethanol exposure. We believe that a significant component of ethanol's actions is mediated by its blockage of these receptors during critical developmental periods. Our focus is on the status and continued development of the cerebellar structures that have survived the binge-like ethanol damage delivered at a time known to cause significant neuronal death. The ultimate goal of this work is then to derive from this knowledge a means or method for the maximum utilization of these remaining structures to provide the best outcome for the individual. Since no therapeutic intervention will replace the lost Purkinje cells, an understanding of the characteristics and nature of alterations in the intricate connections between climbing fibers and the surviving Purkinje neurons holds the promise of ameliorative treatments for children suffering from FASD.