TRH and Energy Homeostasis

描述（由申请人提供）：促甲状腺激素释放激素（TRH）不仅通过影响甲状腺功能，而且通过影响摄食行为、产热和自主调节，在能量稳态调节中发挥重要作用。我们假设，两个不同的人群TRH产生神经元位于内侧/室周与前小细胞亚部下丘脑室旁核（PVN）有关键作用的协调努力，以调解TRH对能量稳态的影响。为了确定这两个TRH神经元群体如何整合到大脑中的能量控制系统中并阐明其特定功能，我们将开发转基因小鼠，其中Cre重组酶选择性地靶向TRH产生细胞。这种方法，连同使用的基因修饰的伪狂犬病病毒（PRV），利用Cre-loxP系统的荧光标记蛋白，GFP的条件复制和表达，将被用来阐明复杂的，多突触电路调节这些神经元组和它们的调节瘦素。此外，使用Cre-lox位点特异性重组，我们建议构建依赖于Cre-mediated重组事件复制的PRV衍生物，但由于gB（病毒粒子的膜融合和跨神经元通道所需的主要膜蛋白）的突变而无法感染其他相邻或跨突触神经元群体。因此，只有表达Cre的神经元将被靶向细胞死亡，从而允许在PVN的每个限定的解剖区域中选择性损失TRH神经元群体，而对相邻群体没有任何影响。使用这些新的“自杀”病毒选择性消融TRH神经元在PVN的每一个细分，最终将允许阐明TRH神经元在前与内侧/室周细分的能量稳态的调节中所施加的生理效应的全部开局，并可能成为神经科学研究的新的神经解剖学工具的一般价值。

DESCRIPTION (provided by applicant): Thyrotropin-releasing hormone (TRH) has an important role in the regulation of energy homeostasis not only through effects on thyroid function, but also on feeding behavior, thermogenesis, and autonomic regulation. We hypothesize that two distinct populations of TRH-producing neurons located in the medial/periventricular vs anterior parvocellular subdivision of the hypothalamic paraventricular nucleus (PVN) have critical roles in a coordinated effort to mediate the effects of TRH on energy homeostasis. To determine how these two TRH neuronal populations are integrated into energy control systems in the brain and elucidate their specific functions, we will develop transgenic mice in which Cre recombinase is selectively targeted to TRH-producing cells. This approach, together with the use of genetically modified pseudorabies virus (PRV) that exploits the Cre-loxP system for conditional replication and expression of the fluorescent marker protein, GFP, will be used to elucidate the complex, multisynaptic circuitries regulating of each of these neuronal groups and their regulation by leptin. In addition, using Cre-lox-site-specific recombination, we propose to construct a PRV derivative that is dependent on a Cre-mediated recombination event for replication, yet unable to infect other adjacent or transsynaptic neuronal populations due to a mutation in gB, a major membrane protein required for membrane fusion and transneuronal passage of virions. Thus, only neurons that express Cre will be targeted for cell death, allowing selective loss of the TRH neuronal population in each defined anatomical region of the PVN without any effects on adjacent populations. The use of these novel "suicide" viruses to selectively ablate TRH neurons in each subdivision of the PVN, will ultimately allow the elucidation of the full gambit of physiologic effects exerted by TRH neurons in the anterior vs medial/periventricular subdivision in the regulation of energy homeostasis, and may become of general value as a new neuroanatomical tool for neuroscience research.