谷氨酰胺对饲喂高精料的奶山羊瘤胃上皮的保护效应研究

本研究旨在探讨过瘤胃谷氨酰胺对饲喂高精料的奶山羊瘤胃上皮屏障的保护效应。实验采用随机区组设计,将12头健康奶山羊随机分为高精料组(n=6)和高精料添加谷氨酰胺组(n=6),谷氨酰胺添加量为50 g/(d·头)。谷氨酰胺处理4周后,每组各选取4头山羊进行屠宰。HE染色、扫描和透射电镜法观察瘤胃上皮的组织形态学变化,实时荧光定量 PCR 法检测瘤胃上皮炎症因子及紧密连接蛋白mRNA的相对表达水平。结果表明,与对照组相比,添加谷氨酰胺显著降低了瘤胃液中丙酸浓度(P<0.01),有降低瘤胃乳酸、提高丁酸浓度的趋势,但对瘤胃液pH、乙酸、异丁酸、总挥发性脂肪酸浓度无显著影响(P>0.05);对组织形态的观察结果表明,添加过瘤胃谷氨酰胺可维持瘤胃复层扁平上皮各细胞层的完整性,保护角质层,减少细胞凋亡;并显著降低瘤胃上皮组织中TNF-α的mRNA相对表达量(P<0.05),显著提高occludin的mRNA相对表达量(P<0.05);但对IFN-γ、IL-1β、IL-6、IL-10、claudin-1、claudin-4和ZO-1 mRNA表达量无显著影响(P>0.05)。结果说明,高精料日粮下添加过瘤胃谷氨酰胺可降低瘤胃上皮的炎症反应,改善上皮紧密连接,从而维护瘤胃上皮屏障的正常功能。

The effect of glutamine supplementation on the barrier function of ruminal epithelium during high grain diet feeding in dairy goats

The effect of protected glutamine supplementation on the barrier function of ruminal epithelium in dairy goats fed high grain diet was investigated using twelve dairy goats that were randomly allocated to 1 of 2 treatments: high-grain (HG) diet group (n=6) or glutamine (Gln) supplementation group (n=6,50 g/d Gln supplementation). After four weeks feeding,four goats in each group were slaughtered to characterize the changes in ruminal epithelial structure,tight junction (TJ) proteins mRNA expression,and inflammatory cytokines mRNA expression using H-E dyeing,scanning and transmission electron microscopy and real-time PCR. Compared with the control,Gln addition reduced (P<0.05) the concentration of propionate,and showed a trend to reduce the lactic acid concentration as well but it increased the butyrate concentration (P>0.05). Gln supplementation did not significantly influence the concentrations of acetate,isobutyl rate and total short-chain fatty acids. In addition,Gln addition up-regulated the gene expression of occludin mRNA expression (P<0.05) and reduced (P<0.05) the mRNA levels of TNF-α in the ruminal epithelia,and had a role in protecting the rumen epithelium. These results indicate that glutamine has a potential to maintain the rumen epithelial structural integrity and barrier function during high grain feeding.