Amylin-mediated control of energy balance in the mesolimbic reward system

描述（由申请人提供）：肥胖是西方社会最普遍和最昂贵的疾病之一，我们目前缺乏有效的非侵入性治疗策略。胰淀素系统是用于减肥的药物方法的有希望的靶标，因为胰淀素类似物减少人类和动物模型中的食物摄入和体重。腹侧被盖区（VTA），一个在调节食物摄入中起重要作用的中脑边缘核，最近被确定为胰淀素介导的摄食控制的作用部位。然而，VTA胰淀素受体激活减少食物摄入的机制尚不清楚。拟议的5年研究职业发展计划的主要目标是促进申请人从博士后过渡到完全独立的学术科学家。这将通过对申请人进行各种分子、神经解剖学和行为技术的培训来实现，这些技术将用于鉴定胰淀素在腹侧被盖区中起作用以减少食物摄入和促进体重减轻的机制。了解更多关于胰淀素参与减少进食的中枢神经系统机制将为肥胖药物治疗的发展提供新的见解。具体目的I阐明了参与VTA胰淀素受体激活的细胞内信号及其与胰淀素诱导的摄食抑制的相关性。本研究旨在确定VTA胰淀素上调和/或激活的信号分子以及诱导这些信号的特定基因和蛋白质表达机制。特异性目的II检验了VTA胰淀素受体活化部分通过调节多巴胺信号传导减少食物摄入的假设。行为，免疫组织化学和伏安法技术将被用来探测腹侧被盖区胰淀素诱导的多巴胺信号的变化，在神经核，一个关键的mesolimbic网站的控制喂养。VTA胰淀素可能影响多巴胺信号传导到其他中脑边缘核的可能性也将被探索。特定目标III评估了VTA胰淀素信号传导对于控制适口的大量营养素（特别是碳水化合物和脂肪）的摄入的作用。行为分析将确定VTA胰淀素受体信号传导调节每种常量营养素摄入的能力，以及摄食后胃肠道反馈对VTA胰淀素介导的脂肪和/或碳水化合物摄入减少的贡献。此外，一种新的腺相关病毒（AAV）-shRNA策略将用于敲低VTA中胰淀素受体的表达。这种方法将用于检查VTA胰淀素信号传导对正常能量平衡和大量营养素摄入的慢性需求。在拟议的研究中使用的离体和体内技术的新组合将提供补充数据，以加深我们对胰淀素如何激活大脑中分布的核团以调节进食和能量平衡的理解，从而为开发更有效的肥胖药物治疗提供重要信息。

DESCRIPTION (provided by applicant): Obesity is one of the most prevalent and costly diseases in Western society, and we currently lack effective, non-invasive treatment strategies. The amylin system is a promising target for a pharmaceutical approach to weight loss, as amylin analogs reduce food intake and body weight in humans and animal models. The ventral tegmental area (VTA), a mesolimbic nucleus that is important in the regulation of food intake, was recently identified as a site of action for amylin-mediated control of feeding. However, the mechanisms by which VTA amylin receptor activation reduces food intake are unknown. The main goal of the proposed 5- year research career development plan is to facilitate the applicant's transition from postdoctoral fellow to a fully independent academic scientist. This wil be accomplished by training the applicant in a variety of molecular, neuroanatomical, and behavioral techniques that will be used to identify mechanisms by which amylin acts in the VTA to reduce food intake and promote weight loss. Understanding more about the central nervous system mechanisms engaged by amylin to decrease feeding will provide new insight into putative targets for the development of obesity pharmacotherapies. Specific Aim I elucidates the intracellular signals engaged by VTA amylin receptor activation and their relevance to amylin- induced suppression of feeding. The studies in this Aim will identify the signaling molecules upregulated and/or activated by VTA amylin and the specific gene and protein expression mechanisms that induce these signals. Specific Aim II tests the hypothesis that VTA amylin receptor activation reduces food intake in part by modulating dopamine signaling. Behavioral, immunohistochemical, and voltammetric techniques will be used to probe VTA amylin-induced changes in dopamine signaling in the nucleus accumbens, a key mesolimbic site for the control of feeding. The possibility that VTA amylin may impinge on dopamine signaling to other mesolimbic nuclei will also be explored. Specific Aim III evaluates the role of VTA amylin signaling for controlling intake of palatable macronutrients, specifically carbohydrate and fat. Behavioral analyses will establish the ability of VTA amylin receptor signaling to modulate intake of each macronutrient, as well as the contribution of post-ingestive gastrointestinal feedback to VTA amylin-mediated reductions in fat and/or carbohydrate intake. Additionally, a novel adeno-associated virus (AAV)-shRNA strategy will be used to knock down amylin receptor expression in the VTA. This approach will be used to examine the chronic requirement of VTA amylin signaling for normal energy balance and macronutrient intake. The novel combination of ex vivo and in vivo techniques utilized in the proposed studies will offer complementary data to deepen our understanding of how amylin activates distributed nuclei in the brain to regulate feeding and energy balance, thus providing important information for the development of more effective obesity pharmacotherapies.