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对酒精滥用和依赖至关重要。人类遗传学研究表明，KOR 系统与酒精依赖有关（Xuei 等，2006）。此外，使用动物进行的行为研究表明，KOR 激动剂可减少自愿乙醇摄入量（Lindholm 等，2001），而 KOR 拮抗剂可减少长期乙醇治疗动物的乙醇摄入量（Walker 和 Koob，2008）。 KOR 系统被认为可以介导包括乙醇在内的滥用药物的烦躁效应，并且最近表明 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 等人，2008)。该提案将检验以下假设：杏仁核中央核 (CeA) 中的 KOR 系统是参与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，并且 CeA 中的 KOR 系统在长期乙醇治疗后失调。第二个要测试的假设是 KOR 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介导从幼年和长期接受乙醇处理的动物的啮齿动物脑切片的 CeA 中乙醇效应中的作用。我们将检查 KOR 系统的强直作用以及 KOR 系统急性激活对 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子区域（外侧和内侧部分）进行，因为这些部分表现出强啡肽（假定的内源性 KOR 配体）的差异分布（Marchant 等，2007）。我们将检查 KOR 拮抗和激活在四种不同条件下的效果，包括（1）对照条件，（2）用 CRF 进行急性体外预处理，（3）用乙醇进行急性体外预处理，以及（4）来自长期乙醇处理的动物和使用等热量对照饮食配对喂养的动物的脑切片。为了研究 KOR 效应是否依赖于 CRF 受体激活，我们将在 CRF 受体拮抗剂存在的情况下重复实验。了解卡帕阿片类药物系统在介导 CeA 酒精作用中的作用应有助于开发改善酒精依赖和滥用的治疗替代方案。 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量饮酒。目前可用的药物干预措施的有益效果有限。该项目将研究酒精依赖背后的候选机制，即杏仁核中的卡帕阿片系统。该项目的成果将有助于开发更有效的药物疗法来改善和/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.