新型神经肽Spexin在斜带石斑鱼摄食调控中的功能研究

Spexin (SPX) is a novel neuropeptide in vertebrates, and considered as a potential anorexigenic factor in feeding regulation. However, the feeding regulatory mechanism of SPX is still unclear. Recently, a new and specific subtype Spexin2 was identified in lower vertebrates. In this study, the orange-spotted grouper (Epinephelus coioides), an important economic fish, will be used as a model to investigate the function of SPXs with the following aspects: ①.To obtain the cDNA sequences of SPXs as well as their receptors (galanin receptors, GALRs)and establish the SPX/GALR signal system; ②.To study the tissue distributions and the localizations of SPXs and GALRs in the brain; ③.To detect the expression profiles of SPXs and GALRs in the hypothalamus under different feeding conditions in order to demonstrate the correlation of SPXs and feeding regulation; ④.To analyze the expressions of the feeding related factors in the hypothalamus by in vitro incubation and in vivo injection of SPXs; ⑤.To obtain the effect of SPXs treatments on feed intake. This project aims at systematically elucidating the physiological functions and molecular mechanisms of SPXs in the feeding regulation of orange-spotted grouper, and will enrich the feeding neuroendocrine system in fish and provide the oretical basis for developing novel neuropeptide products for improving food intake and utilization.

Spexin (SPX)是近年来发现的新型神经肽，被认为是潜在的摄食抑制关键因子，但其调控摄食的作用机制等尚未清楚。尤其是最近在低等脊椎动物中发现特有的新亚型Spexin2后，引起了更广泛的关注。本项目以重要海水经济鱼类斜带石斑鱼为研究对象，将从分子、细胞和生理等层次开展以下研究：①.克隆获得SPXs及其受体galanin receptors（GALRs）的cDNA全长序列，并鉴定斜带石斑鱼SPX/GALR信号系统；②.研究SPXs及GALRs的组织分布与脑区定位；③.检测SPXs及GALRs在不同摄食条件下的表达；④.通过离体和在体实验，确定SPXs与其他摄食因子的调控关系及信号通路；⑤.探讨SPXs对饵料摄取的实际影响。本项目将系统地阐明SPX在斜带石斑鱼摄食调控中的生理功能及作用机制，丰富了石斑鱼等鱼类摄食调控的神经内分泌系统，并为研发提高饵料摄取及利用的新型制剂提供理论参考。

Spexin (SPX)是近年来发现的新型神经肽，被认为是潜在的摄食抑制关键因子，但其调控摄食的作用机制等尚未清楚。尤其是最近在低等脊椎动物中发现特有的新亚型Spexin2后，引起了更广泛的关注。本项目以重要海水经济鱼类斜带石斑鱼为研究对象，研究结果发现GALR1b受体能和SPXs两种配体结合，并激活下游的PKA信号通路，从中表明GALR1b是斜带石斑鱼SPX信号系统主要信号介导受体，并通过激活下游PKA通路来传导信号。斜带石斑鱼SPX1和SPX2具有显著的组织表达及生理功能差异。利用荧光免疫组织化学的方法检测SPX1在脑区的定位，发现SPX1主要定位于TeV、PPa、PMmc、NLT、Tpp和NDL等区域，而SPX2的神经元定位较集中，主要定位于PPa和Tpp区域；利用合成人工SPX1和SPX2多肽开展离体和在体实验，结果发现SPX1能抑制orexin和gh基因表达和促进pomc基因的表达，显示出SPX1是一个饱食因子;而SPX2对相关的摄食调控因子没有显著性的调控作用，但能促进生殖调控因子gnrh1和lhβ基因的表达，显示出具有明显的生殖调控能力，是一个生殖正调控因子; 利用PKA通路抑制阻断通路研究，结果发现SPX1能通过PKA信号通路调控摄食调控因子orexin和pomc基因的表达；SPX2同样能通过PKA通路调控gnrh1基因，但对lhβ基因的调控不显著，可能SPX2对lhβ具有的调控是间接调控关系。本项目将系统地阐明SPX在斜带石斑鱼摄食调控中的生理功能及作用机制，丰富了石斑鱼等鱼类摄食调控的神经内分泌系统，并为研发提高饵料摄取及利用的新型制剂提供理论参考。