Regulatory Role of Growth Hormone Secretagogue Receptor

描述：（从申请人的摘要扫描）长期目标是 了解生长激素促分泌素受体（GHS-R）在 内分泌学这种G蛋白偶联受体已被表征、克隆， 并被确立为脉动生长激素（GH）的重要调节剂 release.在人类中，每天用合成GHS-R配体MK-0677治疗 逆转与年龄相关的GH脉冲释放和血清IGF-1的下降 程度.这种年轻化的功能益处包括以下方面的改善： 睡眠质量，改善身体成分和适度改善 实力因此，GHS-R途径是内分泌学中的重要因素 衰老的迹象本研究的重点是GHS-R在下丘脑调节中的作用 GH释放GHS-R、生长激素释放激素 生长激素释放激素（GHRH）神经元、生长激素（GH）、生长抑素（sst）和神经肽Y（NPY）在 将评价GH脉动性的夹带。NPY和SST的作用 将使用NPY缺失小鼠和sstr 2缺失小鼠进行评价。NPY的特异性 将使用NPY-受体缺失小鼠和拮抗剂来确定效果 对NPY受体亚型有选择性。MK-0677对GHRH表达的影响 弓形神经元将通过利用转基因小鼠进行视觉鉴定， 增强型绿色荧光蛋白在GHRH的控制下表达 启动子这些GHRH神经元将被表征为离子通道表达 采用真实的时间RT-PCR和电生理学和药理学活性。 将检测MK-0677对特定通道活性的修饰。到 直接确定参与的底物的机制和磷酸化 GHS-R信号传导，如Kvl.2和PYK 2，将重组组分 在稳定表达GHS-R的爪蟾卵母细胞和垂体衍生的GC细胞中。 探讨GHS受体与下丘脑其他神经元之间的信号通路 在体内，将绘制下丘脑GHS-R神经元的投射。这 将通过将IREStau-lacZ整合到小鼠GHS-R基因座中来完成， 同源重组GHS-R下丘脑神经元的布线将是 其特征在于β-半乳糖苷酶的免疫染色。的结果予以 实验将提供有关中枢机制的重要信息， 衰老内分泌学。

DESCRIPTION: (Scanned from the applicant's abstract) The long-term objective is to understand the role of the Growth Hormone Secretagogue Receptor (GHS-R) in endocrinology. This G-protein coupled receptor has been characterized, cloned, and established as an important regulator of pulsatile Growth Hormone (GH) release. In humans, daily treatment with the synthetic GHS-R ligand MK-0677 reverses the age-related decline in both pulsatile GH release and serum IGF-1 levels. Functional benefits of this rejuvenation include improvements in quality of sleep, improved body composition and modest improvements in strength. Hence, the GHS-R pathway is an important factor in the endocrinology of aging. This proposal focuses on the role of GHS-R on hypothalamic regulation of GH release. The interplay between GHS-R, growth hormone releasing hormone (GHRH) neurons, GH, somatostatin (sst) and neuropeptide Y (NPY) in regulating the entrainment of GH pulsatility will be evaluated. The roles of NPY and sst will be evaluated using NPY null mice and sstr2 null mice. Specificity of NPY effects will be determined using NPY-receptor null mice and antagonists selective for NPY-receptor subtypes. Effects of MK-0677 on GHRH expressing arcuate neurons will be identified visually by exploiting transgenic mice where enhanced green fluorescent protein is expressed under the control of the GHRH promoter. These GHRH neurons will be characterized for ion channel expression using real time RT-PCR and activity by electro physiology and pharmacology. Modification of specific channel activity by MK-0677 will be tested. To directly determine the mechanism and phosphorylation of substrates involved in GHS-R signaling, such as a Kvl.2 and PYK2, the components will be reconstituted in Xenopus oocytes and in pituitary derived GC cells that stably express GHS-R. To investigate signaling pathways between GHS-R and other hypothalamic neurons in vivo, the projections of hypothalamic GHS-R neurons will be mapped. This will be accomplished by integrating IREStau-lacZ into the mouse GHS-R locus by homologous recombination. The wiring of GHS-R hypothalamic neurons will be characterized by immunostaining for beta-galactosidase. The results of these experiments will provide important information in central mechanisms involved in the endocrinology of aging.