过度训练对大鼠小肠粘膜机械屏障的影响及谷氨酰胺的干预作用

Glutamine Supplementation Reduces the Harmful Effect of Overtraining on the Mechanical Barrier of Small Intestinal Mucosa in Rats

目的:探讨过度训练对大鼠小肠粘膜机械屏障的影响及谷氨酰胺的干预作用和机制。方法:实验大鼠随机分为对照组(C)、过度训练组(HT)、谷氨酰胺干预组(HT+Gln)。两HT组大鼠进行每周6次、共9周的力竭性跑台运动。HT+Gln组大鼠在运动前按1.5 g/kgBW剂量补充谷氨酰胺。9周后,末次运动训练后第二天晨取材,通过HE染色观察各组大鼠安静时小肠粘膜组织结构,并测定血浆二胺氧化酶(DAO)活性、内毒素含量以及小肠SOD活性和MDA含量。结果:(1)与对照组比较,HT组大鼠小肠绒毛水肿增粗,数目明显减少,绒毛间隙变大,绒毛高度显著缩短,部分粘膜上皮细胞出现肿胀、变性,甚至坏死等病理性变化。且血浆DAO活性和内毒素含量显著升高,小肠组织SOD活性显著降低,MDA含量显著升高。(2)HT+Gln组大鼠小肠粘膜形态结构与对照组相比无明显变化。与HT组相比,HT+Gln组血浆DAO活性和内毒素含量显著降低,小肠组织MDA含量显著下降,SOD活性虽有所升高,但无显著性差异。结论:过度训练可使肠道清除自由基能力下降,氧自由基生成增加,从而导致小肠粘膜萎缩和损伤,破坏小肠粘膜屏障,引起小肠粘膜通透性增加,引起"内毒素易位"。补充Gln可以增强机体抗氧化能力,有效缓解过度训练大鼠肠道粘膜的损伤,降低小肠粘膜通透性,对保护小肠粘膜的屏障功能有重要作用。

Objective To explore whether the glutamine（Gln）supplementation reduces the harmful effect of overtraining on the mechanical barrier of small intestinal mucosa.Methods Experimental rats were randomly divided into control group（C）,overtraining group（HT）and glutamine intervention group（HT＋Gln）.Exhaustive training in group HT was carrying on for 9 weeks,6 times/week.The rats in group HT＋Gln was supplied with Gln（1.5 g/kgBW）before training.Sampling was performed in the morning in the 2nd day after the last training,and the morphosis of small intestine mucosa was observed by HE staining.Plasma diamine oxidase（DAO）activity,endotoxin concentration as well as MDA concentration,SOD activity in small intestines tissue were examined.Results ① As compared with the group C,in group HT edema and thickening of small intestinal villus appeared,the number of villus significantly reduced,the gap between the villi increased;villus height significantly shortened;swelling,degeneration,and necrosis appeared in some epithelial cells;plasma DAO activity and endotoxin concentration increased obviously（P 0.01）;MDA content in small intestine increased obviously and SOD activity decreased remarkably（P 0.01）.② There were no significant changes in small intestinal morphology between group C and group HT＋Gln.The plasma DAO activity and endotoxin in the group HT＋Gln were significantly lower than in group HT.Conclusion Over-training could result in atrophy and damage of the small intestinal mucosa,destruction of small intestinal mucosal barrier,and increased intestinal mucosal permeability.Supplementation of exogenous Gln before intensive training could effectively alleviate the damage of intestinal mucosa in over-training rats,reduce intestinal epithelial permeability,and thus protect the function of small intestinal mucosal barrier.