Central Amygdala Kappa Opioid Receptor Mechanisms Underlying Effects of Ethanol

描述（由申请人提供）：kappa阿片受体（KOR）及其内源性激动剂dynorphin已被确定为酒精滥用和依赖的关键。人类遗传学研究表明，KOR系统与酒精依赖有关（xue et al., 2006）。此外，使用动物进行的行为研究报告称，KOR激动剂会减少自愿乙醇摄入量（Lindholm等人，2001年），而KOR拮抗剂会减少长期乙醇治疗动物的乙醇摄入量（Walker和Koob， 2008年）。有研究表明，KOR系统可介导包括乙醇在内的滥用药物的焦虑效应，最近也有研究表明，KOR系统在促肾上腺皮质激素释放因子（CRF）系统的下游发挥作用（Land等，2008）。这一提议将验证中央杏仁核（CeA）的KOR系统（一个涉及压力和焦虑行为以及药物成瘾的关键大脑区域）介导急性乙醇效应以及CeA中的KOR系统在慢性乙醇治疗后失调的假设。第二个有待检验的假设是，KORs通过CeA中的CRF系统介导乙醇效应。本研究将使用全细胞膜片钳电生理技术检查KOR系统及其与CRF系统的相互作用。我们将研究这些系统在调节乙醇对幼年和长期乙醇处理的啮齿动物脑切片中CeA的作用。我们将研究KOR系统的滋补作用，以及KOR系统的急性激活对CeA网络中自发兴奋性和抑制性神经传递的影响。研究将在中央杏仁核的两个亚区，外侧和内侧分区进行，因为这些分区表现出dynorphin（假定的内源性KOR配体）的不同分布（Marchant等，2007）。我们将在四种不同的条件下研究KOR拮抗和激活的效果，包括(1)对照条件，(2)体外急性预处理CRF，(3)体外急性预处理乙醇，以及(4)慢性乙醇处理动物和等量对照饮食成对喂养动物的脑片。为了研究KOR效应是否依赖于CRF受体的激活，我们将在CRF受体拮抗剂存在的情况下重复实验。了解kappa阿片系统在CeA中介导酒精作用的作用，将有助于开发治疗替代方案，以改善酒精依赖和滥用。

DESCRIPTION (provided by applicant): The kappa opioid receptor (KOR) and its endogenous agonist, dynorphin, have been identified as critical for alcohol abuse and dependence. Human genetic studies have shown that the KOR system is associated with alcohol dependence (Xuei et al., 2006). In addition, behavioral studies using animals reported that KOR agonists decrease voluntary ethanol intake (Lindholm et al., 2001), while KOR antagonists decrease ethanol intake in chronically ethanol-treated animals (Walker and Koob, 2008). The KOR system has been suggested to mediate dysphoric effects of drugs of abuse including ethanol, and it has recently suggested that KOR system plays a role downstream of the corticotrophin releasing factor (CRF) system (Land et al., 2008). This proposal will test the hypothesis that the KOR system in the central amygdala nucleus (CeA), a critical brain region involved in stress and anxiety behavior as well as drug addiction, mediates acute ethanol effects and that the KOR system in CeA is dysregulated following chronic ethanol treatment. A second hypothesis to be tested is that KORs mediate ethanol effects through the CRF system in CeA. This study will examine the KOR system and its interaction with the CRF system using whole cell patch clamp electrophysiological techniques. We will investigate the role of these systems in mediating ethanol effects in the CeA in rodent brain slices taken from naove and chronically ethanol-treated animals. We will examine tonic effects of the KOR system as well as effects of acute activation of the KOR system on spontaneous excitatory and inhibitory neurotransmission in the CeA network. Studies will be performed in two subregions of central amygdala, lateral and medial divisions, as these divisions exhibit differential distribution of dynorphin (the putative endogenous KOR ligand) (Marchant et al., 2007). We will examine the effect of KOR antagonism and activation in four different conditions including (1) control conditions, (2) acute in vitro pretreatment with CRF, (3) acute in vitro pretreatment with ethanol, and (4) in brain slices from chronic ethanol treated animals and pair-fed animals with an equicaloric control diet. To investigate whether the KOR effect is dependent on CRF receptor activation, we will repeat experiments in the presence of CRF receptor antagonists. Understanding the role of the kappa opioid system in mediating alcohol actions in CeA should facilitate development of therapeutic alternatives to ameliorate alcohol dependence and abuse. PUBLIC HEALTH RELEVANCE: Alcohol dependence is a chronic disease characterized by uncontrollable excessive consumption of alcohol. Currently available pharmacological interventions have limited beneficial effects. This project will be investigating a candidate mechanism underlying alcohol dependence, a kappa opioid system in the amygdala. The outcome of this project will contribute to develop more effective pharmacological therapeutics to ameliorate and/or treat alcohol dependence.