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Ghrelin是生长素促分泌受体的内源性配体,刺激摄食并增加体重。已有研究证实ghrelin刺激摄食的作用靶点主要是下丘脑弓状核(hypothalamic arcuate nucleus,ARC)内的神经肽Y(neuropeptide Y,NPY)/刺鼠色蛋白相关蛋白(agouti-related peptide,AgRP)神经元。除下丘脑外,脑干尾部迷走复合体具有ghrelin受体,是ghrelin调控摄食活动的另一靶点。本实验旨在验证ghrelin作用于脑干尾部所诱发的摄食增加是否需要下丘脑NPY/AgRP神经元参与。在大鼠延髓背侧迷走复合体(dorsal vagalcomplex,DVC)微量注射20pmol的ghrelin,用摄食自动分析仪测量大鼠的摄食反应,用荧光定量PCR技术测定ARC的NPY/AgRP mRNA的表达水平,同时利用免疫组化技术测定ARC的NPY阳性神经元数量及光密度。结果显示,与对照组(DVC微量注射生理盐水)相比,ghrelin微注射组大鼠摄食量增加,其累积摄食量在注射后2h达最高峰;ARC处NPY/AgRP mRNA的表达水平、NPY免疫阳性神经元的数量及光密度也明显增加,且均在ghrelin注射后2h增高达到高峰。以上结果提示,大鼠DVC注射ghrelin可能通过上行纤维激活弓状核NPY/AgRP神经元,介导大鼠的多食反应。
Ghrelin is an endogenous ligand for the auxin-secreting receptor that stimulates food intake and increases body weight. It has been reported that ghrelin stimulates food intake mainly through neuropeptide Y (NPY) / agouti-related peptide (AgRP) in hypothalamic arcuate nucleus (ARC) )Neurons. In addition to the hypothalamus, the bradyndal tail vaginal complex has the ghrelin receptor, which is another target of ghrelin’s regulation of feeding activity. The purpose of this experiment was to verify whether the increased feeding induced by ghrelin on the tail of the brainstem involved the hypothalamic NPY / AgRP neurons. Microinjection of 20 pmol of ghrelin into the dorsal vagal complex (DVC) of rats was used to measure the feeding response of the rats by using an automatic food ingestion analyzer. The expression level of NPY / AgRP mRNA in ARC was measured by fluorescence quantitative PCR The number and optical density of NPY positive neurons in ARC were determined by immunohistochemistry. The results showed that compared with the control group (microinjection of saline DVC), the ghrelin microinjection group increased the food intake and reached the peak at 2h after injection. The NPY / AgRP mRNA expression level at ARC and NPY immunization The number of positive neurons and optical density also significantly increased, and were increased 2h after ghrelin injection peaked. The above results suggest that injection of ghrelin into rat DVC may activate the NPY / AgRP neurons of the arcuate nucleus through the upper fibers and mediate the multi-feeding response in rats.