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，而且还通过影响摄食行为、产热和自主神经调节，在调节能量平衡方面发挥重要作用。我们假设，位于下丘脑室旁核(PVN)的内侧/周围室旁核(PVN)的两个不同的TRH产生神经元亚群在调节TRH对能量平衡的影响的协调努力中具有关键作用。为了确定这两个TRH神经元群体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Cre重组酶选择性靶向TRH产生细胞的转基因小鼠。这一方法与利用Cre-loxP系统有条件地复制和表达荧光标记蛋白GFP的转基因伪狂犬病病毒(PRV)的使用将被用于阐明复杂的多突触回路对每个神经元组的调节以及瘦素对它们的调节。此外，利用Cre-lox位点特异性重组，我们建议构建一种依赖于Cre介导的重组事件进行复制的PRV衍生物，但由于Gb的突变而无法感染其他邻近或跨突触的神经元群体，Gb是膜融合和病毒粒子跨神经元通过所需的主要膜蛋白。因此，只有表达Cre的神经元将成为细胞死亡的靶点，允许选择性地丢失PVN每个已定义解剖区域中的TRH神经元群体，而不会对邻近群体产生任何影响。使用这些新型的“自杀”病毒选择性地消融PVN各亚区的TRH神经元，最终将有助于阐明TRH神经元在调节能量平衡方面所发挥的全部生理作用，并可能成为神经科学研究的一种新的神经解剖学工具。

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.