Neurosteroid Modulation of Ethanol Withdrawal Severity

描述（由申请人提供）：神经甾体别孕烯醇酮（ALLO）是GABAA受体的有效正调节剂，有证据表明GABA能神经甾体是GABAA受体和乙醇（EtOH）选择性作用的内源性调节剂。本提案建立在选择性繁殖的戒断性癫痫倾向（WSP）和耐药（WSR）雄性小鼠的当前资助期内产生的结果基础上。WSP小鼠在EtOH戒断期间内源性ALLO水平持续降低，以及对ALLO抗惊厥作用的耐受性，这一发现与EtOH戒断期间WSP与WSR系中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定线差异可能反映了GABAA受体上ALLO局部浓度的改变与EtOH戒断期间GABAA受体对ALLO敏感性的伴随变化之间的平衡。因此，拟定研究的目的是确定WSP小鼠在EtOH戒断期间对ALLO耐受性的机制和作用部位（目的3），改变的局部内源性ALLO水平（目的2）和改变的GABAA受体亚基表达（目的4）对WSP和WSR小鼠在EtOH戒断严重程度期间ALLO敏感性的线差异的相对贡献，以及WSP和WSR小鼠乙醇戒断期间生物合成酶5 α-还原酶（Srd 5a 1）的解剖学定位和调节（目的1）。结果模式将提供重要信息，说明特定大脑区域中GABAA受体的激活是否足以改变EtOH戒断严重程度或EtOH戒断期间对ALLO的敏感性，以及特定大脑区域中局部ALLO浓度的关键影响。EtOH戒断严重程度。这种多学科方法将进一步检验以下假设：内源性ALLO水平降低（其改变GABA能张力）以及GABAA受体敏感性降低导致WSP小鼠戒断严重程度增加。这项研究的长期目标是了解戒断严重程度增加的遗传易感性的机制。这些信息将有助于我们了解酒精戒断的机制，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.