NEUROSTEROIDS AND ETHANOL INTERACTIONS

描述：(改编自《调查者摘要》)本报告的目的 建议是探索内源性的潜在作用 3α-羟基-5α-孕烷-20-酮(3α5α-THP) 乙醇的电生理和行为作用，包括 酒精耐受性的发展。我们最近发现乙醇 给药使大鼠血浆和大脑中的 强效GABAA受体神经活性类固醇，3alpha5pha-THP 药理上相关的浓度。乙醇对人体健康的影响 3大脑皮层α5α-THP水平呈时间和剂量依赖关系 足以增强GABAA受体功能。此外，还有一个很强的 酒精睡眠时间与大脑皮层水平的相关性 3Alpha5α-THP。相比之下，大脑中3alpha5pha-THP的水平没有改变 通过酒精依赖大鼠的急性酒精攻击，因此，耐受性可能 发展到乙醇对3α5α-THP诱导的影响。损失 乙醇诱导的3alpha5-THP水平可能是耐受的基础 乙醇的药理作用。因此，我们建议测试整体 3α，5α-THP介导乙醇药理作用的假说 在活体内。 第一个目标是研究3alpha5pha-THP在行为学中的作用。 以及乙醇的神经生理效应。3Alpha5Alpha-THP地层将是 通过预先使用类固醇生物合成抑制剂来预防 乙醇对神经元放电频率、GABAA受体介导的抑制作用的影响 自发性神经元活动、中毒、空中翻正反射和癫痫 将测量阈值。3Alpha-5pha-THP的作用也将是 在缺乏3α-羟基类固醇的条件性基因敲除小鼠中进行的研究 脱氢酶--3alpha5pha-THP形成的最后一步。第二个目标是 确定3alpha5pha-THP是否在耐受性的形成中起作用 使用敲除小鼠和类固醇生物合成抑制剂的乙醇。这个 第三个目标将集中在3alpha5α-THP积累的机制上 在注射乙醇后。将进行研究以确定是否 乙醇直接改变3α5α-THP生物合成的活性 酵素。初步结果表明，乙醇可能会增加3alpha5pha-THP 生物合成，而高剂量乙醇可能会释放或揭示 3Alpha5α-THP。乙醇对人外周血中~(3α)α-THP释放的影响 将对培养的星形胶质细胞进行测量。这些研究将解决以下问题 快速时间点(秒到分钟)的乙醇，这可能与 乙醇的电生理作用。这些研究可能会阐明一种新的 乙醇在中枢神经系统中的作用机制并解释为什么乙醇的作用 GABA能神经传递不能用直接解释 乙醇对GABAA受体的作用。这次调查的结果将是 扩大我们对神经类固醇在酒精作用中的潜在作用的认识 和酒精耐受性，并可能识别参与发病的新因素。 酗酒。

DESCRIPTION: (Adapted from the Investigator's Abstract) The objective of this proposal is to explore the potential role of endogenous 3alpha-hydroxy-5alpha-pregnan-20-one (3alpha5alpha-THP) in the electrophysiological and behavioral actions of ethanol, including the development of ethanol tolerance. We recently discovered that ethanol administration to rats produces an elevation in plasma and brain levels of the potent GABAA receptor neuroactive steroid, 3alpha5alpha-THP, to pharmacologically relevant concentrations. The effects of ethanol on 3alpha5alpha-THP levels in cerebral cortex are time and dose dependent and sufficient to potentiate GABAA receptor function. Moreover, there is a strong correlation between ethanol sleep time and cerebral cortical levels of 3alpha5alpha-THP. In contrast, brain levels of 3alpha5alpha-THP are not altered by acute ethanol challenge in ethanol dependent rats, therefore, tolerance may develop to the effect of ethanol on the induction of 3alpha5alpha-THP. The loss of ethanol induction of 3alpha5alpha-THP levels may underlie tolerance to the pharmacological effects of ethanol. Therefore, we propose to test the overall hypothesis that 3alpha, 5alpha-THP mediates pharmacological effects of ethanol in vivo. The first goal is to investigate the role of 3alpha5alpha-THP in the behavioral and neurophysiological effects of ethanol. 3alpha5alpha-THP formation will be prevented by pretreatment steroid biosynthesis inhibitors and the effects of ethanol on neuronal firing rates, GABAA receptor-mediated inhibition of spontaneous neuronal activity, intoxication, aerial righting reflex and seizure thresholds will be measured. The role of 3alpha 5alpha-THP will also be investigated in conditional knockout mice that lack 3alpha-hydroxysteroid dehydrogenase-the final step in 3alpha5alpha-THP formation. The second aim will determine if 3alpha5alpha-THP plays a role in the development of tolerance to ethanol using both knock out mice and steroid biosynthesis inhibitors. The third aim will focus on the mechanisms of 3alpha5alpha-THP accumulation following ethanol administration. Studies will be conducted to determine if ethanol directly alters the activity of the 3alpha5alpha-THP biosynthetic enzymes. Preliminary results suggest that ethanol may increase 3alpha5alpha-THP biosynthesis, while high dose ethanol may release or uncover a "store" of 3alpha5alpha-THP. The effect of ethanol on 3alpha5alpha-THP release from cultured astrocytes will be measured. These studies will address the effects of ethanol at rapid time points (seconds to minutes) that may be relevant to the electrophysiological actions of ethanol. These studies may elucidate a new mechanism of ethanol action in the CNS and explain why the effects of ethanol on GABAergic neurotransmission could not be adequately explained by the direct action of ethanol at GABAA receptors. The results of this investigation will extend our knowledge of the potential role of neurosteroids in ethanol action and ethanol tolerance and may identify new factors involved in the etiology of alcoholism.