TRH and Energy Homeostasis

描述（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，而且在摄食行为、产热和自主调节中发挥着重要的调节能量稳态的作用。我们假设位于下丘脑室旁核（PVN）的内侧/室周和前旁细胞细分的两个不同的TRH产生神经元群在协调努力介导TRH对能量稳态的影响中起关键作用。为了确定这两种TRH神经元群是如何整合到大脑的能量控制系统中并阐明它们的特定功能，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。这种方法与利用Cre-loxP系统进行有条件复制和荧光标记蛋白GFP表达的转基因伪狂犬病毒（PRV）一起，将用于阐明调节这些神经元群的复杂的多突触回路以及瘦素对它们的调节。此外，利用cre -lox位点特异性重组，我们建议构建一种PRV衍生物，该衍生物依赖于cre介导的重组事件进行复制，但由于膜融合和病毒粒子跨神经元传代所需的主要膜蛋白gB突变而无法感染其他邻近或跨突触神经元群体。因此，只有表达Cre的神经元才会成为细胞死亡的目标，从而允许在PVN的每个定义的解剖区域选择性地丢失TRH神经元群，而不会对相邻的群体产生任何影响。使用这些新型“自杀”病毒选择性地消融PVN各细分中的TRH神经元，最终将阐明TRH神经元在前、中、室周围细分中对能量稳态调节的生理作用，并可能成为神经科学研究的一种新的神经解剖学工具，具有普遍价值。

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.