AMPK在日粮纤维调控母猪原始卵泡激活与发育中的作用及机制

Anestrous and low conception rate resulting from impaired follicle development and oocyte quality is the contributing factor for the large proportion of culling sows in commercial swine farms. AMPK and mTORC1, acting as the key proteins to sense the cellular metabolic switch, are recently demonstrated to govern the awakening of primordial follicles and their subsequent maturation in mice. Preliminary research in our laboratory revealed an improved reproductive performance not only in the first parity but also the subsequent five parties in sows fed diets supplemented with an appropriate ratio of dietary fiber. However, it remains unclear whether the awakening and maturation of primordial follicles could be controlled by the ovarian AMPK and mTORC1 signaling pathways induced by the dietary fiber derived metabolic signals, short-chain fatty acids (SCFAs) or serotonin. In this project, the regulation of awakening and development of primordial follicles in gilts fed a dietary fiber rich diet will be investigated firstly, and an appropriate level of dietary fiber will be optimized. Moreover, the metabolic signals induced by dietary fiber will be validated for their roles in the regulation of primordial follicle awakening and development using exogenous infusion test. Finally, the role of AMPK and mTORC1 signaling pathway in control of primordial follicle awakening and maturation by SCFAs or serotonin will be investigated using ovary culture in vitro and granulosa cell culture in vitro. The results of this project will disclosure the relationship between dietary fiber and follicle development, and have a practical significance to improve the fertility of sows in a short and lifetime manner.

生产中因乏情、受胎率低等繁殖障碍导致母猪淘汰率高，主要原因在于卵泡发育受阻和卵母细胞质量不佳。鼠上研究证实，细胞内感知营养代谢状态的腺苷酸活化蛋白激酶（AMPK）和雷帕霉素靶蛋白复合物1（mTORC1）信号可调控原始卵泡激活与发育。申请人前期研究发现，母猪饲喂富含纤维日粮显著影响第1胎及随后繁殖性能。但是，日粮纤维是否通过其代谢底物短链脂肪酸（SCFAs）或代谢激素血清素调控卵巢AMPK和mTORC1信号影响原始卵泡激活和发育仍未见报道。本项目首先明确日粮纤维对母猪原始卵泡激活与发育的调控效应，筛选母猪原始卵泡适度激活的纤维水平；进一步通过颈静脉恒流灌注技术、卵巢及颗粒细胞培养模型研究SCFAs或血清素与AMPK和mTORC1信号通路的互作关系在母猪原始卵泡激活与发育中的作用。本研究对揭示日粮纤维营养与卵泡发育的机理具有重大理论意义，并对提高母猪短期和长期繁殖力具有重要的实践意义。

项目背景：实际生产中乏情、受胎率低、产仔数低等繁殖障碍突出，原因在于卵泡发育受阻和卵母细胞质量不佳。卵泡发育受阻主要表现在母猪原始卵泡不激活或过度激活导致母猪不发情或提早发情，增加母猪的早期淘汰；卵母细胞质量不佳主要表现在生长卵泡募集成大卵泡的数量减少、受胎率降低和产仔数减少。AMPK是调控原始卵泡激活与发育的重要信号，也是纤维营养影响细胞代谢的关键分子，纤维能否通过AMPK影响原始卵泡激活与发育进而调控其后续繁殖成绩尚不清楚。. 主要研究内容：考察日粮纤维水平对后备母猪卵巢原始卵泡激活与发育的调控效应，揭示日粮纤维及代谢信号调控母猪原始卵泡的激活与存活的分子机制，探明母猪后备期日粮添加纤维对初情启动及后续繁殖效率的调控效应，以原始卵泡的激活和发育为靶标探索了后备母猪的适宜碳水化合物供能比例及饲喂模式。 . 重要结果与关键数据：玉米-豆粕型日粮基础上额外提供75%纤维（以菊粉和纤维素按1:4比例），使后备母猪从33kg阶段开始至配种阶段采食495g/d的膳食纤维，防止原始卵泡过度激活与闭锁，卵巢上卵母细胞的数量和质量比对照组分别提高56.6%和52.5%；卵巢AMPK/mTORC1/Caspase-3信号通路是纤维影响影响原始卵泡激活与存活的关键分子网络，而肠道微生物-血清素-褪黑素代谢通路是纤维影响卵泡激活的代谢途径。母猪后备期日粮添加鼠李糖、木糖等适宜可溶性纤维组分，初情日龄提前15.6天，初情体重降低12.2kg，初情背膘减少0.84mm，3-5胎窝均总产仔数和产活仔猪数分别提高1.35头和1.46头；碳水化合物、蛋白质和脂质供能比分别为73%、9%、18%时，可防止卵巢原始卵泡过度激活与凋亡；母猪77kg~配种阶段饲喂频率由6次降为1次，卵巢切片上单位面积生长卵泡数量增加52%，第3情期黄体数增加10个。. 科学意义：本项目阐明了营养对猪卵泡发育的调控机制，以卵母细胞数量和质量为标识构建营养及饲喂技术，纠正传统以生长性能为标识确定后备母猪营养参数的局限，对于充分发掘母猪的繁殖潜能，延长繁殖寿命，降低淘汰率具有重要的生产价值，因而具有十分广阔的应用前景。