Control of Ethanol Intake by an mGluR5-PKCe Pathway

描述(由申请人提供)：这是一项竞争性更新申请，重点关注mGluR5-PKC5信号通路在乙醇自我给药和恢复乙醇寻求行为中的作用。在目前的资助期间，我们已经证明了这一信号通路是啮齿动物自愿摄入乙醇的重要中介。MGluR5受体与PKC5活性是生化偶联的，mGluR5受体的拮抗剂减少了野生型小鼠的酒精消耗，但不能减少缺乏PKC5的小鼠的酒精消耗。我们开发了一种静脉注射(IV.V.)模型。酒精在大鼠体内的自我给药，对酒精强化的药理操作以及对酒精寻求行为恢复的研究，这是一种广泛使用的复发模型。利用这个模型，我们发现伏隔核(NAC)是一个关键的脑区域，通过mGluR5和PKC5之间的信号传递参与乙醇自我给药的调节。最后，我们产生了新的初步数据表明，PKC5介导了mGluR5受体的磷酸化，我们假设这在调节该受体的配体结合特性和表面表达方面发挥了作用。在这一新的应用中，我们将进一步研究mGluR5和PKC5之间的相互信号以及该信号通路调节乙醇自我给药和恢复乙醇寻找行为的神经电路。在特定的目标1中，我们将研究PKC5对mGluR5受体功能的调节。具体地说，我们将研究脑室内注射PKC5易位抑制剂MYR-5V1-2后，背侧和腹侧纹状体mGluR5受体的配体结合特性和细胞表面表达的变化。在特定的目标2中，我们将研究mGluR5-PKC5信号介导乙醇增强的神经回路。这将通过测量静脉注射来检查。向腹侧被盖区(VTA)或内侧前额叶皮质(MPFC)微量注射选择性mGluR5拮抗剂Mtep和PKC5易位抑制剂MYR-5V1-2后，给予乙醇自我给药，这是已知的介导乙醇增强效应的区域。在具体目标3中，我们将研究mGluR5-PKC5信号介导线索诱导的乙醇寻找行为恢复的神经电路。这将通过单独微量注射选择性mGluR5拮抗剂MTEP以及与PKC5易位抑制剂MYR-5V1-2一起注入VTA或杏仁基底外侧核(BLA)后测量线索诱发的酒精寻找来检验，这是已知的介导刺激-奖赏联系的区域。总之，拟议的研究将深入了解mGluR5和PKC5之间的双向串扰，以及这一信号通路在酒精自我给药和线索诱发的复发样行为中所起的作用，这将有望促进酒精中毒和其他酒精使用障碍的治疗。公共卫生相关性：这项建议的目标是调查mGluR5-PKC5信号在调节啮齿动物的酒精消耗和复发中的作用。进一步了解mGluR5和PKC5信号对这些行为的贡献将有望转化为治疗人类酒精中毒的改进疗法。

DESCRIPTION (provided by applicant): This is a competitive renewal application focused on the role of the mGluR5-PKC5 signaling pathway in ethanol self-administration and reinstatement of ethanol-seeking behavior. During the current funding period, we have demonstrated that this signaling pathway is an important mediator of voluntary ethanol intake in rodents. mGluR5 receptors are biochemically coupled to PKC5 activity, and antagonists of mGluR5 receptors reduce ethanol consumption in wildtype mice but not mice lacking PKC5. We have developed a model of intravenous (i.v.) ethanol self-administration in the rat that is amenable to pharmacological manipulation of ethanol reinforcement as well as the study of reinstatement of ethanol seeking behavior, a widely used model of relapse. Using this model, we have identified the nucleus accumbens (NAc) as a critical brain region that is involved in the regulation of ethanol self-administration by signaling between mGluR5 and PKC5. Finally, we have generated novel preliminary data showing that PKC5 mediates phosphorylation of the mGluR5 receptor, which we hypothesize plays a role in regulating the ligand binding properties and surface expression of this receptor. In this renewal application, we will further examine the reciprocal signaling between mGluR5 and PKC5 as well as the neural circuitry where this signaling pathway regulates ethanol self-administration and reinstatement of ethanol-seeking behavior. In Specific Aim 1, we will examine the regulation of mGluR5 receptor function by PKC5. Specifically, we will examine changes in the ligand binding properties and cell surface expression of mGluR5 receptors in the dorsal and ventral striatum following intracerebroventricular administration of the PKC5 translocation inhibitor myr-5V1-2. In Specific Aim 2, we will examine the neural circuitry where mGluR5-PKC5 signaling mediates ethanol reinforcement. This will be examined by measuring i.v. ethanol self-administration following microinjection of the selective mGluR5 antagonist MTEP alone and in combination with the PKC5 translocation inhibitor myr-5V1-2 into the ventral tegmental area (VTA) or medial prefrontal cortex (mPFC), regions that are known to mediate the reinforcing effects of ethanol. In Specific Aim 3, we will examine the neural circuitry whereby mGluR5-PKC5 signaling mediates cue-induced reinstatement of ethanol-seeking behavior. This will be examined by measuring cue-evoked ethanol-seeking following microinjection of the selective mGluR5 antagonist MTEP alone and in combination with the PKC5 translocation inhibitor myr-5V1-2 into the VTA or basolateral amygdala (BLA), regions that are known to mediate stimulus- reward associations. Together, the proposed studies will provide insight into the bidirectional crosstalk between mGluR5 and PKC5 and the role this signaling pathway plays in ethanol self-administration and cue-evoked relapse-like behavior, which will hopefully lead to improved treatments for alcoholism and other alcohol use disorders. PUBLIC HEALTH RELEVANCE: The goal of this proposal is to investigate the role of mGluR5-PKC5 signaling in the regulation of ethanol consumption and relapse in rodents. Further understanding of the contributions of mGluR5 and PKC5 signaling to these behaviors will hopefully translate into improved therapies for the treatment of alcoholism in humans.