Orexin Induced Gene and Protein Expression Patterns in the rLH

描述（由申请人提供）： 肥胖在世界范围内的流行率有所增加，这被认为是由于肥胖促进环境和遗传因素的影响。尽管存在这些影响，但仍有个体和动物抵抗肥胖。自发性身体活动（SPA），产生非运动活动产热（NEAT），可以减少体重增加。将下丘脑神经肽食欲素A（OxA）注射到下丘脑外侧喙部（rLH）中可增加SPA水平并增加肥胖抵抗力。驱动SPA的神经机制尚未完全定义。了解NEAT的调节机制将有可能开发预防和治疗肥胖的新方法。OxA已被证明在各种细胞模型中激活细胞外信号调节激酶1/2（ERK 1/2）和p38有丝分裂原激活磷酸激酶（MAPK）。据报道，全球缺乏这两种激酶抑制剂MKP-1的小鼠具有肥胖抵抗性，部分原因是能量消耗和SPA增加，但尚不清楚OxA信号传导是否改变。OxA最近也被证明在常氧条件下增加下丘脑组织中的ATP和转录因子缺氧诱导因子-1a（HIF-1a）。这是值得注意的，因为HIF-1a增加氧化磷酸化。另外的独立研究表明，HIF-1a的表达部分受MAPK和转录辅激活因子PGC-1a的调节。PGC-1a是线粒体生物发生的调节剂，可以同时上调保护免受氧化应激的基因，并增加ATP的产生。本申请中提出的中心假设是：SPA对体重增加的影响部分取决于rLH中的OxA信号传导，其改变了参与短期和长期细胞内代谢功能的基因和蛋白质。 将测试该假设的三个具体目标是：1）在体外确定OxA是否增加 HIF-1通过ERK 1/2和p38 MAPK的激活而表达。2)体外测试OxA诱导的HIF-1 <$激活是否介导大鼠rLH切片中的细胞内代谢变化。3)在体内评价OxA治疗是否改善或预防饮食诱导的肥胖发生后rLH中ERK 1/2-p38-MAPK-HIF-1- PGC-1通路和细胞内代谢反应性的变化。提出的工作的近期目标将使用体外和体内模型来表征OxA诱导的SPA中重要的细胞机制，其长期目标是通过对这些确定的途径进行药理学操作来开发肥胖症的治疗方法。预期的结果是OxA将增加激活的神经元的短期和长期细胞内代谢能力，从而维持升高的SPA和肥胖抵抗力。这将影响肥胖研究领域， 细胞内OxA信号传导可能有助于肥胖抵抗的机制。对当前范式的创新和挑战是，拟议的研究提出了一种新的机制，通过这种机制，OxA提高SPA，这是通过改变基因，增加激活的rLH神经元的细胞内代谢阻力。这种机制可能是赋予长期肥胖抵抗的原因，并将为肥胖提供新的治疗靶点。

DESCRIPTION (provided by applicant): Obesity has increased in prevalence worldwide, which is thought to be due to the influences of an obesity-promoting environment and genetic factors. Despite these influences there are individuals and animals that resist obesity. Spontaneous physical activity (SPA), which generates nonexercise activity thermogenesis (NEAT), can reduce weight gain. Injections of hypothalamic neuropeptide orexin A (OxA) into the lateral rostral hypothalamus (rLH) increased levels of SPA and increase obesity resistance. The neurological mechanism that drive SPA are not fully defined. Understanding the mechanism(s) by which NEAT is regulated will have the potential to develop novel approaches to preventing and treating obesity. OxA has been shown to activate extracellular signal-regulated kinases 1/2 (ERK1/2) and p38 mitogen activated phosphate kinase (MAPK) in various cell models. Mice globally lacking the inhibitor for both these kinases, MKP-1, have been reported to be obesity resistant due in part to an increase in energy expenditure and SPA, but it is unknown whether OxA signaling is altered. OxA has also been recently shown to increase ATP and the transcription factor hypoxia inducible factor-1a (HIF-1a) in hypothalamic tissue under normoxic conditions. This is noteworthy given that HIF-1a increases oxidative phosphorylation. Additional independent studies have shown that HIF-1a expression is regulated in part by MAPKs and the transcriptional coactivator PGC-1a. PGC-1a is a regulator of mitochondrial biogenesis, can simultaneously upregulate genes that protect against oxidative stress, and increases ATP production. The central hypothesis proposed in this application is: SPA effects on weight gain depend in part on OxA signaling in the rLH, which alters genes and proteins involved in short- and long-term intracellular metabolic function. The three specific aims that will test this hypothesis are: 1) Determine in vitro if OxA increases HIF-1¿ by the activation of ERK1/2 and p38 MAPKs. 2) Test in vitro whether OxA-induced activation of HIF-1¿ mediates intracellular metabolic changes in rat rLH sections. 3) Evaluate in vivo if OxA treatment ameliorates or prevents changes in the ERK1/2-p38-MAPK-HIF-1¿- PGC-1¿ pathway and intracellular metabolic responsiveness in the rLH following the development of diet-induced obesity. The immediate goal of the work proposed will characterize cellular mechanisms important in OxA-induced SPA using in vitro and in vivo models, with a long-term goal of developing therapeutic treatments for obesity through pharmacological manipulation of these identified pathways. The expected outcome is that OxA will increase the short- and long-term intracellular metabolic capacity of activated neurons, resulting in the maintenance of elevated SPA and obesity resistance. This will impact the field of obesity research by identifying a mechanism through which intracellular OxA signaling might contribute to obesity resistance. The innovation and the challenge to current paradigms are that the proposed studies suggest a new mechanism through which OxA elevates SPA, which is by altering genes that increase intracellular metabolic resistance in activated rLH neurons. This mechanism may be responsible for conferring long-term obesity resistance and would provide a new therapeutic target for obesity.