Central Amygdala Kappa Opioid Receptor Mechanisms Underlying Effects of Ethanol

描述（由申请人提供）：κ阿片受体（KOR）及其内源性激动剂强啡肽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（Xuei et al.，2006年）。此外，使用动物的行为研究报告了KOR激动剂减少自愿的乙醇摄入（Lindholm等人，2001），而KOR拮抗剂降低了长期乙醇处理动物的乙醇摄入（步行者和Koob，2008）。已经提出KOR系统介导包括乙醇在内的滥用药物的烦躁效应，并且最近提出KOR系统在促肾上腺皮质激素释放因子（CRF）系统的下游起作用（Land et al.，2008年）。这项建议将测试的假设，即KOR系统在中央杏仁核（CeA），一个关键的大脑区域参与应激和焦虑行为以及药物成瘾，介导急性乙醇的影响和KOR系统在CeA失调慢性乙醇治疗。有待检验的第二个假设是KORs通过CeA中的CRF系统介导乙醇效应。本研究将利用全细胞膜片钳电生理技术研究KOR系统及其与CRF系统的相互作用。我们将研究这些系统在介导从naove和慢性乙醇处理动物的啮齿动物脑切片中的CeA乙醇效应中的作用。我们将研究紧张的KOR系统的影响，以及急性激活的KOR系统的自发兴奋性和抑制性神经传递的CeA网络的影响。研究将在中央杏仁核的两个亚区，外侧区和内侧区进行，因为这些区表现出强啡肽（推定的内源性KOR配体）的差异分布（Marchant et al.，2007年）。我们将在四种不同的条件下检查KOR拮抗和激活的效果，包括（1）对照条件，（2）CRF急性体外预处理，（3）乙醇急性体外预处理，和（4）慢性乙醇处理动物和等卡路里对照饮食配对喂养动物的脑切片。为了研究KOR效应是否依赖于CRF受体活化，我们将在CRF受体拮抗剂存在下重复实验。了解κ阿片系统在介导CeA中的酒精作用中的作用，应有助于开发治疗替代方案，以改善酒精依赖和滥用。 公共卫生相关性：酒精依赖是一种慢性疾病，其特征是无法控制的过度饮酒。目前可用的药物干预具有有限的有益效果。这个项目将调查潜在的酒精依赖的候选机制，杏仁核中的kappa阿片系统。该项目的结果将有助于开发更有效的药物治疗，以改善和/或治疗酒精依赖。

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.