NEUROSTEROID MODULATION OF ETHANOL WITHDRAWAL SEVERITY

神经活性类固醇 3α-羟基-5α-pregnan-20-one（3α，5α-Por allopregnanolone）是 GABAA 受体的有效正调节剂。与 3α、5α-P 可能代表生理上重要的神经调节剂的推测一致，在选择性繁殖的戒断性癫痫易发 (WSP) 和抗性 (WSR) 小鼠中进行的初步研究发现，3α、5α-P 的内源水平较低或对 3α、5α-P 的敏感性降低可能与乙醇 (EtOH) 戒断严重程度增加相关。在退出 EtOH 的 WSP 中，对 3α、5-α-P 的敏感性降低，以及内源性 3α、5α-P 减少。这将导致 EtOH 戒断期间 WSP 线的神经兴奋性更高。本提案将使用多学科方法来检验以下假设：EtOH 戒断严重程度的遗传差异部分归因于 3α、5-α-P 敏感性和/或生物合成的改变。与具体目标 1 和 2 相关的研究将确定乙醇戒断严重程度与慢性乙醇诱导的内源性 3α、5α-P 浓度以及 3α、5α-P 生物合成酶、5α-还原酶的活性和/或基因表达的变化之间的时间关系。乙醇戒断期间 5α-还原酶抑制的生理后果将在具体目标 2 中进行检查。与具体目标 4 和 5 相关的研究将确定对 3α、5α-P 的行为敏感性和 GABAA 受体对 3α、5α-P 的功能敏感性之间的对应关系。行为、生化和分子策略的结合使用将确定 3α、5α-P 作为乙醇戒断严重程度的神经调节剂的重要性。此外，在EtOH戒断期间对3α、5α-P的敏感性和/或3α、5α-P生物合成的选定品系差异的证明将提供额外的证据，表明改变大脑中的局部神经活动类固醇环境可以差异调节GABAA受体（即WSP和WSR），并导致在EtOH戒断期间WSP与WSR品系中的神经兴奋性更高。这项研究的长期目标是了解如何在基因水平上调节对慢性酒精的有害反应（即导致戒断性癫痫发作的身体依赖）的潜在机制。这些信息不仅有助于我们了解酒精戒断的机制，而且有助于制定治疗酒精依赖的新策略。

The neuroactive steroid 3alpha-hydroxy-5alpha-pregnan-20-one (3alpha, 5alpha-Por allopregnanolone) is a potent positive modulator of GABAA receptors. Consistent with the speculation that 3alpha, 5alpha-P may represent a physiologically significant neuromodulator, preliminary studies in the selectively bred Withdrawal Seizure-Prone (WSP) and- Resistant (WSR) mice found that lower endogenous levels of, or decreased sensitivity to, 3alpha, 5alpha-P may be correlated with increased ethanol (EtOH) withdrawal severity. In EtOH-withdrawing WSPs, the reduced sensitivity to 3alpha, 5-alpha-P, as well as the decrease in endogenous 3alpha, 5alpha-P. This would lead to greater neural excitability in the WSP line during EtOH withdrawal. The present proposal will use a multi-disciplinary approach to test the hypothesis that genetic differences in EtOH withdrawal severity are due in part, to alterations in sensitivity, to and/or biosynthesis of, 3alpha, 5-alpha-P. Studies related to Specific Aims 1 and 2 will determine the temporal relationship between EtOH withdrawal severity and the chronic EtOH- induced alterations in endogenous 3alpha, 5alpha-P concentration and activity and/or gene expression of the 3alpha, 5alpha-P biosynthetic enzyme, 5alpha-reductase. The physiological consequences of 5alpha- reductase inhibition during EtOH withdrawal will be examined in Specific Aim 2. Studies related to Specific Aims 4 and 5 will determine the correspondence between behavioral sensitivity to 3alpha, 5alpha-P and functional sensitivity of GABAA receptors to 3alpha, 5alpha-P. The combined use of behavioral, biochemical and molecular strategies will determine the importance of 3alpha, 5alpha-P as a neuromodulator of EtOH withdrawal severity. Further, the demonstration of selected line differences in sensitivity to, and/or biosynthesis of, 3alpha, 5alpha-P during EtOH withdrawal will provide additional evidence that altering the local neuroactivity steroid environment in the brain can differentially modulate GABAA receptors (i.e., WSP and WSR) and lead to the greater neural excitability in the WSP versus WSR line during EtOH withdrawal. The long term goal of this research is to understand mechanisms underlying how deleterious responses to chronic alcohol (i.e., physical dependence leading to withdrawal seizures) are regulated at the genetic level. Not only will this information aid in our understand of the mechanisms underlying alcohol withdrawal, but this knowledge would help in the development of new strategies for the treatment of alcohol dependence.