Effects--Ethanol--Dendritic Smooth Endoplasmic Reticulum

由于酒精对平衡和运动协调的有害影响，进一步了解小脑皮层唯一的输出神经元浦肯野神经元（PN）的乙醇相关作用是必要的。长时间的乙醇消耗导致树突退化和树突光滑内质网（SER）的扩张。PN树突内的SER储存钙离子，这一功能可能被乙醇相关的失衡所扰乱。此外，在老年大鼠中反复观察到，PN树突中乙醇相关的SER扩张可能预测并促进乙醇相关的树突退化。本提案的第一个目的是表征长时间乙醇消耗期间PN树突中SER扩张在几个时间点的发展。这将把乙醇相关的SER扩张发生的时间与报道的PN树突退化的时间联系起来。第二个目的是确认和表征平行纤维中乙醇相关的SER扩张，颗粒神经元（GN）的轴突。平行纤维为突触PN提供主要的突触输入，突触前平行纤维中乙醇相关的SER扩张与突触后PN树突之间可能存在因果关系。SER扩张很可能是神经元失衡的标志，可能严重影响小脑输出。120只老龄雄性F344大鼠和30只老龄雌性F3244大鼠分为3个治疗组（50只/组）。治疗组包括食物对照组、配对喂养组和乙醇组。每组10只雄性将分别接受5周、10周、20周和40周的治疗。雌性大鼠的治疗时间将由PN树突和平行纤维SER扩张达到显著水平的时间点决定。治疗后，对大鼠实施安乐死，取下小脑，准备进行透射电子显微镜（TEM）观察。扫描的TEM阴性图像分析将用于定量PN树突分支，分支点，棘和平行纤维中SER剖面的最大和最小直径。

Further understanding of ethanol-related effects of the Pukinje neuron (PN), the sole output neuron of the cerebellar cortex, is essential due to the deleterious effects of alcohol on balance and motor coordination. Lengthy periods of ethanol consumption result in dendritic regression and dilatation of the dendritic smooth endoplasmic reticulum (SER) within the extensive dendritic arbor of PN. The SER within PN dendrites stores calcium ions, a function that may be upset by ethanol-related imbalances. Ethanol-related SER dilatation in PN dendrites, moreover, may predict and contribute to the ethanol-related dendritic regression that has been repeatedly observed in old rats. The first aim of this proposal is to characterize the development of SER dilation in PN dendrites at several time points during a lengthy period of ethanol consumption. This will relate the time when ethanol-related SER dilatation occurs to the time when PN dendritic regression has been reported. The second aim is to confirm and characterize ethanol-related SER dilatation in parallel fibers, the axons of granule neurons (GN). Parallel fibers provide a major synaptic input to the PN and a causal relationship may exist between ethanol-related SER dilatation in the presynaptic parallel fiber and the postsynaptic PN dendrite. SER dilatation is most probably a marker of neuronal imbalances that could severely impact on cerebellar output. One hundred and twenty old male F344 and 30 old female F3244 rats will be assigned to three treatment groups (50 rats/group). Treatment groups will include a chow control group, a pair-fed group, and an ethanol group. Ten males from each treatment group will be treated for a 5,10,20 or 40 week period, respectively. Length of treatment for the female rats will be determined by the time point at which SER dilatation reached significant levels in both PN dendrites and parallel fibers. Following treatment, rats will be euthanized, the cerebella removed and prepared for transmission electron microscopy (TEM). Image analysis of scanned TEM negative will be used to quantitative the maximum and minimum diameters of SER profiles in PN dendritic branches, branch points, and spines, and in parallel fibers.