Neurosteroid Modulation of Ethanol Withdrawal Severity

描述（由申请人提供）：神经类固醇异孕烷醇酮（ALLO）是GABAA受体的有效正调节剂，有证据表明GABAA能神经类固醇是GABAA受体的内源性调节剂和乙醇（EtOH）的选择性作用。本提案建立在当前资助期选择性繁殖的退缩癫痫倾向（WSP）和抵抗（WSR）雄性小鼠的结果基础上。研究发现，在EtOH戒断期间，WSP小鼠的内源性ALLO水平持续下降，同时对ALLO的抗惊厥作用产生耐受性，这与WSP与WSR系在EtOH戒断期间更大的神经兴奋性一致。ALLO对EtOH戒断严重程度的调节作用的选择系差异可能反映了在EtOH戒断期间GABAA受体局部ALLO浓度的变化与GABAA受体对ALLO敏感性的变化之间的平衡。因此，拟议研究的目的是确定WSP小鼠在EtOH戒断期间对ALLO耐受的作用机制和部位（Aim 3），局部内源性ALLO水平的改变（Aim 2）和GABAA受体亚基表达的改变（Aim 4）对WSP和WSR小鼠在EtOH戒断严重程度期间ALLO敏感性的相对贡献。以及WSP和WSR小鼠EtOH戒断过程中生物合成酶5a-还原酶（Srd5a1）的解剖定位和调控（目的1）。结果的模式将提供关于特定脑区GABAA受体的激活是否足以改变EtOH戒断严重程度或在EtOH戒断期间对ALLO的敏感性，以及特定脑区局部ALLO浓度对EtOH戒断严重程度的关键作用的基本信息。这种多学科的方法将进一步验证内源性ALLO水平的降低（这会改变GABAA能张力）以及GABAA受体敏感性的降低，导致WSP小鼠戒断严重程度的增加。这项研究的长期目标是了解增加戒断严重程度的遗传易感性的机制。这一信息将有助于我们理解酒精戒断的机制，并有助于制定治疗酒精依赖的新策略。

DESCRIPTION (provided by applicant): The neurosteroid allopregnanolone (ALLO) is a potent positive modulator of GABAA receptors, and evidence suggests that GABAergic neurosteroids are endogenous modulators of GABAA receptors and of selective effects of ethanol (EtOH). The present proposal builds on results generated in the current period of funding in the selectively bred Withdrawal Seizure-Prone (WSP) and -Resistant (WSR) male mice. The finding that WSP mice had a persistent decrease in endogenous ALLO levels during EtOH withdrawal, in conjunction with tolerance to ALLO's anticonvulsant effect, is consistent with greater neural excitability in the WSP vs. WSR line during EtOH withdrawal. The selected line differences in the modulatory effect of ALLO on EtOH withdrawal severity likely reflects a balance between alterations in local concentration of ALLO at GABAA receptors and the concomitant change in GABAA receptor sensitivity to ALLO during EtOH withdrawal. Thus, the goals of the proposed studies are to determine the mechanism and site(s) of action underlying the tolerance to ALLO during EtOH withdrawal in WSP mice (Aim 3), the relative contribution of altered local endogenous ALLO levels (Aim 2) and altered expression of GABAA receptor subunits (Aim 4) to the line difference in ALLO sensitivity during EtOH withdrawal severity in WSP and WSR mice, and the anatomical localization and regulation of the biosynthetic enzyme 5a-reductase (Srd5a1) during EtOH withdrawal in WSP and WSR mice (Aim 1). The pattern of the results will provide essential information on whether activation of GABAA receptors in particular brain regions will be sufficient to alter EtOH withdrawal severity or sensitivity to ALLO during EtOH withdrawal as well as the critical involvement of local ALLO concentration in a specific brain region on EtOH withdrawal severity. This multidisciplinary approach will further test the hypothesis that a decrease in endogenous ALLO levels, which alters GABAergic tone, in conjunction with a decrease in GABAA receptor sensitivity, contribute to the increased withdrawal severity in WSP mice. The long-term goal of this research is to understand mechanisms underlying a genetic predisposition for increased withdrawal severity. This information will aid in our understanding of the mechanisms underlying alcohol withdrawal and will help in the development of new strategies for the treatment of alcohol dependence.