NEUROSTEROIDS AND ETHANOL INTERACTIONS

这项建议的目的是探索内源性3a-羟基-5a-孕酮-20-酮的潜在作用。 (3a，5a-THP)在乙醇的电生理和行为作用中的作用，包括乙醇胺的形成 宽容。我们最近发现，给大鼠注射乙醇会使血浆和大脑中的含量升高 强效GABAA受体神经活性类固醇水平。3a、5a-THP。在药理上相关 浓度。乙醇对大脑皮层3a、5a-THP水平的影响具有时间和剂量依赖性 足以增强GABAA受体功能。此外，酒精睡眠与睡眠之间有很强的相关性。 3a.5a-THP的时间和大脑皮层水平。相比之下，脑内3a，5a-THP的水平不会因急性发作而改变 因此，对乙醇依赖大鼠的耐受可能发展为乙醇对大鼠的影响。 3a，5a-THP的诱导。乙醇诱导的3a，5a-THP水平的丧失可能是耐受的基础 乙醇的药理作用。因此，我们建议检验3a，5cc-THP的总体假设 在体内介导乙醇的药理作用。 第一个目标是研究3a，5a-THP在行为和神经生理效应中的作用。 乙醇。3a，5cc-THP的形成将被预先的类固醇生物合成抑制剂和 乙醇对神经元放电频率的影响，GABAA受体介导的自发神经元活动抑制， 将测量醉酒、空中翻正反射和癫痫阈值。3a，5a-THP的作用也将是 在缺乏3a-羟基类固醇脱氢酶的条件性基因敲除小鼠中进行的研究-3a，5a的最后一步- THP地层。第二个目标将确定3a，5oC-THP是否在耐受性的发展中起作用 使用敲除小鼠和类固醇生物合成抑制剂的乙醇。第三个目标将集中在机制上 乙醇处理后3a，5cc-THP的积累。将进行研究以确定乙醇是否 直接改变3a，5cc-THP生物合成酶的活性。初步结果表明，乙醇可能 增加3a，5a-THP的生物合成，而高剂量乙醇可能释放或发现3a，5oC-THP的“储备”。这个 测定乙醇对培养的星形胶质细胞释放3oC，5a-THP的影响。这些研究将针对 乙醇在可能与电生理活动相关的快速时间点(秒到分钟)的影响 乙醇。这些研究可能会阐明乙醇在中枢神经系统中作用的新机制，并解释为什么 乙醇对GABA能神经传递的直接作用不能很好地解释 GABA.4受体。这项研究的结果将扩大我们对神经类固醇潜在作用的认识。 在酒精作用和酒精耐受性中的作用，并可能确定涉及酒精中毒病因学的新因素。

The objective of this proposal is to explore the potential role of endogenous 3a-hydroxy-5a-pregnan-20-one (3a,5a-THP) in the electrophysiological and behavioral actions of ethanol, including the development of ethanpl tolerance. We recently discovered that ethanol administration to rats produces an elevation in plasma and brain levels of the potent GABAA receptor neuroactive steroid. 3a,5a-THP. to pharmacologically relevant concentrations. The effects of ethanol on 3a,5a-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 3a.5a-THP. In contrast, brain levels of 3a,5a-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 3a,5a-THP. The loss of ethanol induction of 3a,5a-THP levels may underlie tolerance to the pharmacological effects of ethanol. Therefore, we propose to test the overall hypothesis that 3a,5cc-THP mediates pharmacological effects of ethanol in vivo. The first goal is to investigate the role of 3a,5a-THP in the behavioral and neurophysiological effects of ethanol. 3a,5cc-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 3a,5a-THP will also be investigated in conditional knock-out mice that lack 3a-hydroxysteroid dehydrogenase - the final step in 3a,5a- THP formation. The second aim will determine if 3a,5oc-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 3a,5cc-THP accumulation following ethanol administration. Studies will be conducted to determine if ethanol directly alters the activity of the 3a,5cc-THP biosynthetic enzymes. Preliminary results suggest that ethanol may increase 3a,5a-THP biosynthesis, while high dose ethanol may release or uncover a "store" of 3a,5oc-THP. The effect of ethanol on 3oc,5a-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 GABA.4 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.