苏氨酸通过调节蛋白激酶B/哺乳动物雷帕霉素靶蛋白信号通路促进断奶仔猪肠道黏膜黏液蛋白表达

Threonine Promotes Gut Mucosal Mucin Expressions in Weaned Piglets via Regulating Protein Kinase B/Mammalian Target of Rapamycin Signaling Pathway

本试验旨在探讨饲粮补充苏氨酸提高肠道黏膜黏液蛋白表达的可能机制。试验选取10头健康的21日龄断奶的"杜×长×大"仔猪,采用单因子试验设计,分成2个组(每组5个重复,每个重复1头猪),分别饲喂真可消化苏氨酸水平为0.74%(基础饲粮)和0.89%的饲粮(在基础饲粮中补充苏氨酸的试验饲粮),试验期为21 d。结果显示:饲粮中补充苏氨酸对断奶仔猪的平均日增重和平均日采食量没有显著影响(P>0.05),但显著降低了料重比(P<0.05),显著提高了空肠和回肠黏膜中黏液蛋白1和2的含量(P<0.05),也显著提高了空肠和回肠黏膜中黏液蛋白1和2的mRNA表达量(P<0.05),并显著刺激了仔猪空肠和回肠黏膜中蛋白激酶B、哺乳动物雷帕霉素靶蛋白、核糖体40S小亚基S6蛋白激酶和真核起始因子4E结合蛋白1的磷酸化(P<0.05)。由此得出,饲粮中补充苏氨酸(使真可消化苏氨酸水平达到0.89%)可促进仔猪肠道黏液蛋白的产生,而这不仅与其可改善黏液蛋白基因的转录,而且可能与其激活蛋白激酶B/哺乳动物雷帕霉素靶蛋白信号通路有关。

This experiment was conducted to determine the possible mechanism of dietary threonine supplementation increasing mucin expressions in gut mucosa.Ten healthy crossbred(DurocxLandrace×Yorkshire)piglets weaned at 21 days of age were randomly allotted into 2 groups(n=5)and fed diets contained 0.74%(the basal diet)and 0.89%(the basal diet supplemented threonine)true ileal digestible threonine.The trial duration was 21 days.The results showed that dietary threonine supplementation did not significantly affect average daily gain and average daily feed intake(P>0.05),significantly reduced feed/gain(P<0.05),significantly increased the contents and mRNA relative expression levels of mucin 1 and 2 in jejunal and ileal mucosa(P<0.05),and significantly stimulated the phosphorylation of protein kinase B,mammalian target of rapamycin,ribosomal protein S6 kinase and eukaryotic translation initiation factor 4 E-binding protein 1 in jejunal and ileal mucosa of weaned piglets(P<0.05).These results suggest that dietary threonine supplementation(0.89%true ileal digestible threonine)promotes the mucin production of gut mucosa in weaned piglets,which may be derived from both the transcription of genes and the activation of protein kinase B/mammalian target of rapamycin signaling pathway.