Novel Mechanisms of Ethanol Potentiation of Rat Basolateral Amygdala GABA

描述(申请人提供)：尽管酒精(Etoh)是已知的最古老的滥用药物之一，但Etoh行为背后的神经生物学机制尚不完全清楚，因此，仍然很难理解一个人如何失去对正常Etoh饮酒的控制，从而导致酒精中毒。酒精中毒经常被发现与焦虑和压力障碍并存，虽然这种共病的病因还不完全清楚，但有人提出，由于乙醇长期以来一直被认为是一种抗焦虑药物，一些人可能会将其作为一种自我药物来缓解焦虑或压力状态。戒掉高水平的乙醇也被证明会导致焦虑/压力状态的增强，这可能导致继续使用和滥用乙醇。因此，据推测，乙醇可能主要影响中枢神经系统(CMS)中调节应激反应和焦虑的区域，如基底外侧杏仁核(BLA)。BLA中的GABA能突触已被证明在焦虑等情绪反应中发挥重要作用。广泛的研究表明，乙醇在CMS中的作用至少部分是由于通过突触前和突触后位置增加了许多大脑区域的GABA能神经传递。去甲肾上腺素(NE)与压力和焦虑症密切相关，已被证明能增加BLA中GABA的释放。我们的初步数据显示，NE受体拮抗剂可以阻断乙醇对GABA能中间神经元亚群的增强作用。因此，我们推测乙醇部分通过NE受体的活性增强了GABA能在BLA中的传递。第一个具体目的是确定急性乙醇促进BLA中两个中间神经元亚群的GABA能神经传递的机制。这一目标将依赖于全细胞膜片钳电生理学方法来确定在BLA组织切片上应用乙醇的作用是否在突触前和/或突触后，利用主要集中于诱发的抑制性突触后电流(IPSCs)的自发和微型突触后电流(IPSCs)和成对脉冲促进研究的组合方案来分离突触前和突触后的乙醇增强GABA能神经传递的成分。第二个特定目的将确定NE与乙醇在BLA GABA能突触上相互作用的机制，以及NE受体亚型介导这一作用。我们将使用如上所述的类似方法以及NE受体激动剂和拮抗剂的组合来分离该脑区中所提出的NE-Etoh相互作用的机制。第三个具体目标将集中于通过吸入室暴露的慢性间歇性乙醇暴露对随后的急性乙醇暴露的影响，以及所研究的目标1和2中的NE-乙醇相互作用。

DESCRIPTION (provided by applicant): Although alcohol (EtOH) is one of the oldest known drugs of abuse, the neuroliogical mechanisms underlying EtOH's actions are not fully known and as such, it remains difficult to understand how one may lose control of normal EtOH drinking resulting in alcoholism. Alcoholism is often found to be comorbid with anxiety and stress disorders, and while the eitology of this comorbidity is not fully known it has been proposed that since EtOH has long been known as an anxiolytic agent, some may imbibe as a way to selfmedicate their anxious or stressed states. Withdrawal from high EtOH levels has also been shown to result in an enhancement of anxious/stressed states, which may result in continued EtOH use and abuse. Therefore, it is hypothesized that EtOH may predominantly effect areas of the central nervous system (CMS) which mediate stress responses and anxiety, such as the basolateral amygdala (BLA). GABAergic synapses in the BLA have been shown to play a major role in emotional responses such as anxiety. Extensive research has shown that at least part of EtOH's effects in the CMS are due to an increase in GABAergic neurotransmission in numerous brain regions through both pre- and post-synaptic sites. Norepinephrine (NE), which is intimately linked to stress and anxiety disorders, has been shown increase GABA release in the BLA. Our preliminary data shows that NE receptor antagonists can block the potentiating effect of EtOH at a subset of GABAergic interneurons. Therefore it is hypothesized that EtOH enhances GABAergic transmission in the BLA in part via NE-receptor activity. The first specific aim is to determine the mechanisms by which acute EtOH enhances GABAergic neurotransmission at two subset of interneurons in the BLA. This aim will rely on whole-cell patch clamp electrophysiological methods to determine if the effects of bath application of EtOH on slices of BLA tissue are pre- and/or post-synaptic utilizing a combination of protocols focusing mainly on evoked inhibitory postsynaptic currents (IPSCs) spontaneous and miniature IPSCs and paired-pulses facilitation studies to isolate pre- and post-synaptic components of the EtOH enhancement of GABAergic neurotransmission. The second specific aim will determine the mechanism by which NE interacts with EtOH at BLA GABAergic synapse and which NE-receptor subtype mediates this effect. We will be using similar methods as described above as well as combinations of NE receptor agonists and antagonists to isolate the mechanism of the proposed NE-EtOH interaction in this brain region. The third specific aim will focus on the effects of chonic intermittent EtOH exposure via inhalation chamber exposure on subsequent acute EtOH exposure and the NE-EtOH interaction studied aims 1 and 2.