Wang Yan, Han Xuefeng, Tan Zhiliang, Kang Jinhe, Wang Zheng
CAS Key Laboratory for Agro-Ecological Processes in Subtropical Region, National Engineering Laboratory for Pollution Control and Waste Utilization in Livestock and Poultry Production, Hunan Provincial Key Laboratory of Animal Nutrition & Physiology and Metabolism, Institute of Subtropical Agriculture, The Chinese Academy of Sciences, Changsha 410125, China.
College of Bioscience and Biotechnology, Hunan Agricultural University, Changsha 410128, China.
Animals (Basel). 2020 Feb 23;10(2):357. doi: 10.3390/ani10020357.
This study aimed to elucidate the effects of a dietary rumen-protected glucose (RPG) addition on uterine involution through the analysis of an insulin-like growth factor (IGF) system and associated pathways in the post-natal endometrium. Twelve Holstein cows were assigned equally to two groups: a control group (CT) and an RPG group (200 g of RPG per cow per day). The plasma content of insulin-like growth factor 1 (IGF1) was determined by using the ELISA method. Expressions of IGF members, the matrix metalloproteinase, protein kinase B (AKT)/mechanistic target of rapamycin complex1 (mTOR) signaling pathway, and cell proliferation factors (proliferating cell nuclear antigen (PCNA) and Ki67) were detected using real-time polymerase chain reaction, Western blot, immunohistochemistry, and immunofluorescence, respectively. The results showed that the positive cells of PCNA and Ki67 were increased in the endometrium of RPG versus CT cows. The RPG addition significantly increased the plasma IGF1 level 14 d after delivery. The mRNA expressions of the IGF family members (IGF1, IGF2, type 1 IGF receptor (IGF1R) and IGF-binding proteins (IGFBP1, IGFBP2, IGFBP4 and IGFBP5)) were upregulated, and mRNA expressions of matrix metalloproteinase MMP3 and MMP9 were downregulated in cows from the RPG group compared with the CT group. Meanwhile, the protein expressions of IGF1, IGF2, IGF1R, IGFBP1 and IGFBP4 were upregulated in cows from the RPG group compared with the CT group. Immunohistochemical analysis identified a positive response for IGF1R and IGF2R in the endometrium of RPG versus CT cows. Furthermore, the RPG supplementation increased the protein expressions of phosphorylated (p)-AKT to total AKT and p-mTOR to total mTOR ratio in the endometrium. The current results indicated that the RPG supplementation promoted the proliferation of endometrial cells by stimulating the IGFs and mTOR/AKT pathway in the early post-natal endometrium of dairy cows.
本研究旨在通过分析产后子宫内膜中胰岛素样生长因子（IGF）系统及相关通路，阐明添加瘤胃保护性葡萄糖（RPG）对子宫复旧的影响。将12头荷斯坦奶牛平均分为两组：对照组（CT）和RPG组（每头奶牛每天添加200克RPG）。采用酶联免疫吸附测定法（ELISA）测定胰岛素样生长因子1（IGF1）的血浆含量。分别使用实时聚合酶链反应、蛋白质免疫印迹法、免疫组织化学和免疫荧光法检测IGF成员、基质金属蛋白酶、蛋白激酶B（AKT）/雷帕霉素靶蛋白复合物1（mTOR）信号通路以及细胞增殖因子（增殖细胞核抗原（PCNA）和Ki67）的表达。结果显示，与CT组奶牛相比，RPG组奶牛子宫内膜中PCNA和Ki67的阳性细胞增加。添加RPG显著提高了分娩后14天的血浆IGF1水平。与CT组相比，RPG组奶牛中IGF家族成员（IGF1、IGF2、1型IGF受体（IGF1R）和IGF结合蛋白（IGFBP1、IGFBP2、IGFBP4和IGFBP5））的mRNA表达上调，基质金属蛋白酶MMP3和MMP9的mRNA表达下调。同时，与CT组相比，RPG组奶牛中IGF1、IGF2、IGF1R、IGFBP1和IGFBP4的蛋白表达上调。免疫组织化学分析显示，与CT组奶牛相比，RPG组奶牛子宫内膜中IGF1R和IGF2R呈阳性反应。此外，补充RPG增加了子宫内膜中磷酸化（p）-AKT与总AKT以及p-mTOR与总mTOR的蛋白表达比值。目前的结果表明，补充RPG通过刺激奶牛产后早期子宫内膜中的IGF和mTOR/AKT通路促进了子宫内膜细胞的增殖。
