Dopaminergic Modulation of Excitatory Transmission in BNST and Regulation by Ethanol

项目总结/摘要 酒精成瘾的特点是反复复发，尽管酒精滥用的负面后果。这 反适应行为被认为是由发生在神经系统中的潜在神经回路的适应引起的。 对慢性酒精滥用的反应。这些适应导致持续的负面情感状态， 戒酒，这促使恢复酒精使用作为一种负强化的手段，或缓解 负面条件。终纹床核（BNST）是压力和焦虑的关键介质 状态和行为反应的压力。压力导致的重新寻求毒品的模型 确定BNST中的去甲肾上腺素信号对复发行为至关重要。去甲肾上腺素能兴奋 BNST通过β-肾上腺素能受体促进焦虑样行为和药物复吸，而 通过α2-肾上腺素能受体抑制BNST活性可减少焦虑样行为。BNST还 从腹侧被盖区（VTA）接受显著的多巴胺能神经支配。的调查 多巴胺能信号传导在BNST中的作用是相对稀疏的，并且有些矛盾。比如说， 低剂量的浴用多巴胺导致BNST的兴奋性活动增加，而高剂量的浴用多巴胺导致BNST的兴奋性活动增加。 导致抑制作用增加。此外，抑制作用被认为是通过以下方式发生的： 多巴胺交叉激活α2肾上腺素能受体。为了解决这些矛盾， 要清楚地了解内源性多巴胺信号以及多巴胺的快速变化 浓度可以选择性地募集突触后受体激活。对多巴胺的研究 信号传导使用快速扫描循环伏安法，其提供多巴胺释放的高时间分辨率， 对终末场的局部电刺激作出反应的摄取。然而，在BNST中，多巴胺和 去甲肾上腺素提供重叠的神经支配，因此两种儿茶酚胺都响应于局部 电刺激和循环伏安法不能区分儿茶酚胺。这阻碍了使用 这项技术在评估多巴胺和去甲肾上腺素信号对 BNST突触生理学。在这个提议中，我们引入了一个模型，在这个模型中，我们光遗传学靶向VTA 多巴胺神经元投射到BNST，这样我们就可以使用选择性的光刺激局部 多巴胺释放，用循环伏安法测量，在BNST切片中，离体。此外，我们建议使用 光刺激多巴胺释放与全细胞电生理学相结合，以测量细胞的 对内源性多巴胺信号的反应。这种离体模型允许我们采用各种药理学方法， 操作，以评估多巴胺信号传导如何整合到突触生理学中，以及在多大程度上整合到突触生理学中。 内源性多巴胺信号募集α2-肾上腺素能受体的激活。最后，我们将研究如何 慢性间歇性乙醇蒸汽暴露改变BNST的多巴胺能调节机制 突触功能

Project Summary/Abstract Alcohol addiction is characterized by repeated relapses to alcohol abuse despite negative consequences. This counter-adaptive behavior is believed to result from adaptations in underlying neurocircuitry which occur in response to chronic alcohol abuse. These adaptations result in persistent negative affective states, during abstinence, which drive reinstatement of alcohol use as a means of negative reinforcement, or relief from negative conditions. The bed nucleus of the stria terminalis (BNST) is a key mediator of stress and anxiety states and behavioral responses to stressors. Models of stress-induced reinstatement of drug seeking have identified norepinephrine signaling in the BNST as critical to relapse behavior. Noradrenergic excitation of the BNST through β-adrenergic receptors promotes anxiety-like behaviors and drug reinstatement, whereas inhibition of BNST activity through α2-adrenergic receptors reduces anxiety-like behaviors. The BNST also receives prominent dopaminergic innervation from the ventral tegmental area (VTA). Investigations into the role of dopaminergic signaling in the BNST are relatively sparse and somewhat contradictory. For example, low doses of bath applied dopamine resulted in increased excitatory activity in the BNST, while high doses resulted in increased inhibitory actions. Further, the inhibitory actions are suggested to occur through dopamine cross-activation of α2-adrenergic receptors. In order to resolve these discrepancies, it is important to have a clear understanding of endogenous dopamine signals and how rapid changes in dopamine concentrations may selectively recruit post-synaptic receptor activation. Often, investigations of dopamine signaling use fast-scan cyclic voltammetry, which provides high temporal resolution of dopamine release and uptake in response to local electrical stimulation of terminals fields. However, in the BNST, dopamine and norepinephrine provide overlapping innervation, thus both catecholamines are released in response to local electrical stimulation, and cyclic voltammetry cannot distinguish between catecholamines. This hinders the use of this technique in assessing the potentially opposing roles of dopamine and norepinephrine signaling on BNST synaptic physiology. In this proposal we introduce a model in which we optogenetically target VTA dopamine neurons projecting to the BNST, such that we may use selective optical-stimulation of local dopamine release, measured with cyclic voltammetry, in BNST slices, ex vivo. Further, we propose to use optically-stimulated dopamine release in combination with whole cell electrophysiology to measure the cellular responses to endogenous dopamine signals. This ex vivo model allows us to employ various pharmacological manipulations to assess how dopamine signaling is integrated into synaptic physiology and to what degree endogenous dopamine signals recruit activation of α2-adrenergic receptors. Finally, we will examine how chronic intermittent ethanol vapor exposure alters the mechanisms of dopaminergic modulation of BNST synaptic function.