Orexin Induced Gene and Protein Expression Patterns in the rLH

描述(由申请人提供)： 肥胖症在世界范围内的流行程度有所上升，这被认为是由于促进肥胖的环境和遗传因素的影响。尽管有这些影响，仍有一些人和动物抵制肥胖。自发的身体活动(SPA)可以产生非运动活动产热(NEAT)，可以减少体重增加。下丘脑神经肽增食欲素A(OXA)注射到下丘脑外侧吻侧(RLH)可增加SPA水平，并增强肥胖抵抗。驱动SPA的神经机制还没有完全确定。了解NEAT的调控机制(S)将有可能开发出预防和治疗肥胖症的新方法。OXA可在多种细胞模型中激活细胞外信号调节蛋白1/2(ERK1/2)和p38丝裂原激活的磷酸激酶(MAPK)。全球范围内缺乏这两种激酶抑制剂MKP-1的小鼠被报道为肥胖抵抗的部分原因是能量消耗和SPA的增加，但尚不清楚OXA信号是否改变。OXA最近还被证明在常氧条件下增加下丘脑组织中的ATP和转录因子低氧诱导因子-1a(HIF-1a)。这一点值得注意，因为HIF-1a增加了氧化磷酸化。更多的独立研究表明，HIF-1a的表达部分受MAPKs和转录辅助激活因子PGC-1a的调节。PGC-1a是线粒体生物发生的调节者，可以同时上调保护免受氧化应激的基因，并增加ATP的产生。在这个应用中提出的中心假设是：SpA对体重增加的影响部分依赖于RLH中的OXA信号，它改变了参与短期和长期细胞内代谢功能的基因和蛋白质。 HIF-1可通过激活ERK1/2和p38MAPKs来实现。2)体外检测OXA诱导的HIF-1激活是否介导了大鼠RLH区细胞内代谢的变化。3)体内评价OXA治疗是否改善或阻止饮食诱导肥胖后RLHERK1/2-p38-MAPK-HIF-1β-PGC-1β通路和细胞内代谢反应的变化。这项工作的近期目标将是利用体外和体内模型描述OXA诱导的SPA中重要的细胞机制，长期目标是通过对这些已识别的途径进行药理学操作来开发肥胖的治疗方法。预期的结果是，OXA将增加激活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。这将影响肥胖研究领域，通过识别 一种细胞内OXA信号可能有助于肥胖抵抗的机制。对现有研究范式的创新和挑战是，拟议的研究提出了一种新的机制，通过改变激活的RLH神经元中增加细胞内代谢阻力的基因，OXA提高了SPA。这一机制可能是导致长期肥胖抵抗的原因，并将为肥胖提供一个新的治疗靶点。

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.