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、非侵入性的治疗策略。由于胰淀素类似物在人类和动物模型中可以减少食物摄入量和体重，因此胰淀素系统是一个很有希望的减肥药物靶点。腹侧被盖区（VTA）是一个中边缘核，在调节食物摄入中起重要作用，最近被确定为amyin介导的摄食控制的一个作用部位。然而，VTA胰淀素受体激活减少食物摄入的机制尚不清楚。5年研究生涯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完成，这些技术将用于确定胰肽在VTA中的作用机制，以减少食物摄入并促进体重减轻。进一步了解胰淀素减少摄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目标。特异性目的1阐明VTA胰淀素受体激活所参与的细胞内信号及其与胰淀素诱导的摄食抑制的相关性。本课题的研究将确定VTA amylin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表达机制。特异性目的II测试了VTA amylin受体激活部分通过调节多巴胺信号减少食物摄入的假设。行为学、免疫组织化学和伏安技术将被用于探测伏隔核（控制摄食的关键中脑边缘部位）中氨基淀粉素诱导的多巴胺信号的变化。VTA胰淀素可能影响多巴胺信号传导到其他中边缘核的可能性也将被探讨。特异性目的III评估VTA amylin信号在控制美味常量营养素（特别是碳水化合物和脂肪）摄入中的作用。行为分析将确定VTA胰淀素受体信号传导调节每种大量营养素摄入的能力，以及摄入后胃肠道反馈对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策略将用于降低VTA中胰淀粉酶受体的表达。这种方法将用于检查VTA胰淀素信号对正常能量平衡和大量营养素摄入的慢性需求。研究中采用的体外和体内技术的新组合将提供补充数据，加深我们对amylin如何激活大脑中的分布核来调节摄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.