GPR35 on Vagal Afferent Neurons as a Peripheral Drug Target for Treating Diet-Induced Obesity

项目摘要 肥胖是心血管和代谢疾病等慢性疾病的主要危险因素， 全球流行率与高热量饮食的过度消费相平行。胃旁路手术是目前 只有有效的治疗维持减肥。然而，手术是昂贵的，侵入性的，并且保留给 严重肥胖的人。胃旁路手术的有效性部分归因于胃分流术的改变。 肠道微生物群和微生物代谢产物的组成，以及外周血中 饱腹激素迷走神经传入神经元（Vagal afferent neurons，VAN）位于肠壁，表达外周神经递质受体。 激素和微生物代谢产物，并将饱腹感信号从胃肠道传递到大脑， 抑制食物摄入。G蛋白偶联受体35（GPR35）被微生物代谢物激活， 在VAN上高度表达。最近的证据表明VAN上的GPR35与CCKAR共定位， 受体介导的饱腹感诱导作用的肠内分泌激素，胆囊收缩素（CCK）。 VAN对包括CCK在内的肠道饱足信号的脱敏先于高脂饮食诱导的体重增加 以及人类肥胖小鼠模型中的食欲过盛，并导致食物摄入增加。高脂肪饮食已经 显示降低犬尿烯酸的血浆水平，犬尿烯酸是一种微生物代谢物，是内源性GPR35配体。 然而，GPR35在外周饱腹感信号传导中的作用尚不清楚。初步数据显示， 使用GPR35激动剂扎普司特的GPR35减少小鼠和体外实验中的食物摄入 证明GPR35抑制降低VAN对CCK的敏感性。因此，我们假设， 高脂饮食减少微生物来源的GPR35配体的产生，导致货车减少 对CCK的敏感性，抑制肠道饱腹感信号，从而增加能量摄入。的假设 将在两个目标中进行测试。目的1将确定CCKAR和GPR35在VAN激活中的相互作用， 大脑中的二级神经元，以及抑制食物摄入。目标2将决定是否增加 通过给予益生元或益生菌，GPR35配体的可用性可以恢复HF饮食诱导的 VAN受损和控制食物摄入。该假设将使用体外， 活体和体内技术，包括钙成像，RNA干扰敲低VAN中的GPR35， 和自动化进食行为监测。这些研究的成功完成将证明 GPR35在外周饱腹感信号传导中的作用，并揭示了治疗肥胖症的潜在治疗靶点。的 我的培训计划将由我的赞助商的指导和加州大学戴维斯分校的特殊设施促进。这 提案描述了一个综合全面的培训计划，以支持科学和专业 发展和推动我朝着我的长期目标，成为一个综合生理学家。

PROJECT SUMMARY Obesity is a major risk factor for chronic diseases, such as cardiovascular and metabolic diseases, and its global prevalence parallels the overconsumption of calorie-dense diets. Gastric bypass surgery is currently the only effective treatment for maintaining weight loss. However, surgery is expensive, invasive, and reserved for people with severe obesity. The effectiveness of gastric bypass surgery is partly attributed to a shift in the composition of the gut microbiota and microbial metabolites, and to the increased production of peripheral satiety hormones. Vagal afferent neurons (VANs) are located in the gut wall, express receptors for peripheral hormones and microbial metabolites, and transmit satiety signals from the gastrointestinal tract to the brain to inhibit food intake. The G-protein coupled receptor 35 (GPR35) is activated by microbial metabolites and is highly expressed on VANs. Recent evidence demonstrates GPR35 on VANs is co-localized with CCKAR, the receptor for mediating the satiety-inducing effects of the enteroendocrine hormone, cholecystokinin (CCK). Desensitization of VANs to intestinal satiety signals, including CCK, precedes high-fat diet-induced weight gain and hyperphagia in mouse models of human obesity and leads to increased food intake. High-fat diet has been shown to reduce plasma levels of kynurenic acid, a microbial metabolite that is an endogenous GPR35 ligand. However, the role of GPR35 in peripheral satiety signaling is unknown. Preliminary data show that activation of GPR35 using the GPR35 agonist, zaprinast, decreases food intake in mice and in vitro experiments demonstrate that GPR35 inhibition decreases the sensitivity of VANs to CCK. Therefore, we hypothesize that high-fat diet decreases the production of microbially-derived GPR35 ligands, leading to reduced VAN sensitivity to CCK, suppression of intestinal satiety signaling thereby increasing energy intake. The hypothesis will be tested in two aims. Aim 1 will determine the interaction of CCKAR and GPR35 in activation of VANs and second order neurons in the brain, and in inhibiting food intake. Aim 2 will determine whether increasing availability of GPR35 ligands, either by administration of prebiotics or probiotics, can restore HF-diet induced impairment of VANs and control food intake. The hypothesis will be tested using a combination of in vitro, intravital, and in vivo techniques including calcium imaging, RNA interference knockdown of GPR35 in VANs, and automated feeding behavior monitoring. Successful completion of these studies will demonstrate the role of GPR35 in peripheral satiety signaling and reveal a potential therapeutic target for treating obesity. The training plan will be facilitated by the mentorship of my sponsor and the exceptional facilities at UC Davis. This proposal describes an integrative and comprehensive training plan to support scientific and professional development and propel me toward my long-term goal of becoming an integrative physiologist.