INTRACELLULAR STUDY OF ETHANOL EFFECTS ON BRAIN NEURONS

该项目的总体目标是描述以下方面的严重影响 乙醇对大脑皮层单个神经元电生理特性的影响 哺乳动物的大脑，并研究基本的离子机制 这些对神经细胞膜的影响。这类研究的最终目标是 阐明乙醇如何改变中枢神经元的信息处理 为了了解人在饮酒过程中大脑功能的变化 用法。拟议的研究将检查离子信使和第二信使。 乙醇对两个重要类群的影响及其机制 儿茶酚胺神经元：蓝斑去甲肾上腺素能神经元 腹侧被盖区(LC)核和多巴胺能神经元 (VTA)。LC是大脑中最大的去甲肾上腺素能核， 参与唤醒水平、警觉性和选择性注意的调节。 乙醇对神经元的急性作用可能是乙醇镇静作用的基础 和选择性注意障碍。LC活动的中断 神经元也可能是酒精戒断的重要组成部分 综合症。VTA的多巴胺能神经元似乎在 调节乙醇的奖赏效应，因此可能至关重要 在控制自愿酒精摄取和滥用方面的重要性。这个 可采用的技术有细胞内电流钳和单电极 在脑片上用尖锐的微电极进行电压钳记录 急性分离的神经元的全细胞记录，均来自成人 老鼠。乙醇将以已知浓度(10-200毫米)在 巴斯。我们现在已经确定了特定的膜电流被增强 乙醇，在行为活性范围内的浓度，即 LC神经元的A-电流和VTA神经元的H-电流。具体目标L和 3旨在研究乙醇增强这些物质的机制 电流及其作用是否通过腺苷环化酶介导 途径或通过细胞外钾或细胞内钙的变化 集中精神。乙醇的这些作用是否调节了它对 本课程将研究LC和VTA神经元的自发放电。具体目标2 和4探索乙醇对人体健康影响的其他可能机制 LC和VTA神经元的放电频率，即对cAMP依赖的作用 LC神经元起搏电流及乙醇引起的神经元收缩 调节电流的特定K+电流(IA、延迟整流、SK或BK) VTA神经元超极化后出现峰电流。基于数据的模型 将被用来解释乙醇如何对已识别的 膜电流对输入输出的影响有很大不同 VTA和LC神经元的功能。关于急性胰腺炎发病机制的信息 乙醇作用是了解其作用机制的必要前提。 乙醇的回报效应，以及乙醇如何 会产生耐受性和身体依赖性。这反过来又应该允许 合理开发更好的治疗方案 习惯性使用酒精与酒精戒断综合症。

The overall objective of this project is to describe the acute effects of ethanol on the electrophysiological properties of single neurons in the mammalian brain and to examine the basic ionic mechanisms which mediate these effects on neuronal membranes. The ultimate goal of such studies is to elucidate how ethanol alters information processing by central neurons in order to understand how brain function changes during human ethanol usage. The proposed studies will examine the ionic and second messenger mechanisms which mediate the effects of ethanol on two important groups of catecholamine neurons: the noradrenergic neurons of the locus coeruleus (LC) nucleus and the dopaminergic neurons of the ventral tegmental area (VTA). The LC is the largest noradrenergic nucleus in the brain and is involved in regulation of arousal level, vigilance and selective attention. Acute ethanol effects on 1 neurons may underlie ethanol's sedative effects and impairment of selective attention. Disruption in the activity of LC neurons may also be an important component of the alcohol withdrawal syndrome. Dopaminergic neurons of the VTA appear to be important in mediating the rewarding effects of ethanol and therefore may be of crucial importance in the control of voluntary ethanol intake and abuse. The techniques to be used are intracellular current clamp and single-electrode voltage clamp recording with sharp microelectrodes in brain slices, and whole cell recording from acutely dissociated neurons, both from adult rats. Ethanol will be applied in known concentrations (10-200 mM) in the bath. We have now identified specific membrane currents which are enhanced by ethanol, in concentrations within the behaviorally active range, namely A-current in LC neurons and h-current in VTA neurons. Specific Aims l and 3 are directed at examining the mechanisms by which ethanol enhances these currents and whether its action is mediated through the adenylate cyclase pathway or by changes in extracellular potassium or intracellular calcium concentration. Whether these actions of ethanol mediate its effects on spontaneous firing in LC and VTA neurons will be examined. Specific Aims 2 and 4 explore other possible mechanisms underlying ethanol's effects on firing rate of LC and VTA neurons, namely, an action on the cAMP-dependent pacemaker current in LC neurons and an ethanol-induced reduction in specific K+ currents (IA, delayed rectifier, SK, or BK) which mediate the spike after hyperpolarization in VTA neurons. A model based on the data will be formulated to explain how the effects of ethanol on identified membrane currents result in its very different effects on the input-output function of VTA and LC neurons. Information about the mechanisms of acute ethanol action is a necessary prerequisite to understanding the mechanisms underlying the rewarding effects of ethanol, as well as how ethanol tolerance and physical dependence develop. This, in turn, should permit the rational development of better therapeutic regimens for treatment of habitual ethanol usage and the ethanol withdrawal syndrome.