谷氨酰胺对肠组织NF-κB及TNF-α的调节与肠损伤保护作用的关系

Relationship between the regulation of intestinal NF-κB and TNF-α by glutamine and the protective effects of glutamine against intestinal injury

目的本研究旨在探讨谷氨酰胺对肠损伤的保护作用是否与调节肠组织核因子-κB(NF-κB)和肿瘤坏死因子-α(TNF-α)的分泌有关。方法 24只日龄10 d的Wistar幼鼠随机分为正常对照组,内毒素血症组和谷氨酰胺组(n=8)。正常对照组采用生理盐水1 mL/kg腹腔注射;内毒素血症组给予LPS 5 mg/kg腹腔注射;谷氨酰胺组给予力肽10 mL/kg+LPS 5 mg/kg腹腔注射。于腹腔注射后3 h处死幼鼠,留取远端回肠组织。行苏木精-伊红染色,光镜下观察肠组织病理改变,RT-PCR检测肠组织NF-κB mRNA的表达,Western blot检测肠组织NF-κB蛋白表达,ELISA法检测肠组织匀浆TNF-α的含量。结果光镜下对照组肠组织结构正常,谷氨酰胺组和内毒素血症组均可见间质和上皮细胞水肿,谷氨酰胺组较内毒素血症组明显减轻;谷氨酰胺组肠组织NF-κB mRNA和NF-κB蛋白表达均较内毒素血症组明显下降(均P<0.01);谷氨酰胺组肠组织TNF-α分泌较内毒素血症组明显减少(P<0.01)。结论谷氨酰胺减轻肠组织损伤的保护作用可能与其下调NF-κB mRNA和蛋白的表达,并降低炎症介质TNF-α的分泌相关。

Objective To study whether the protective effects of glutamine against intestinal injury are associated with the regulation of intestinal secretion of NF-κB and TNF-α by glutamine. Methods Twenty-four 10-day-old Wistar rat pups were randomly intraperitoneally injected with normal sodium of 1 mL/kg（control group;n=8）,LPS of 5 mg/kg（endotoxemia group;n=8） or LPS of 5 mg/kg plus glutamine of 10 mL/kg（glutamine group;n=8）.The rats were sacrificed 3 hrs after injection.A segment of distal ileum was dissected.The pathologic changes of the small intestine were observed under an optical microscope（hematoxylin-eosin staining）.The expression of intestinal NF-κB mRNA and protein were detected by RT-PCR and Western blot respectively.The TNF-α level in intestinal tissues was measured using ELISA. Results The structure of the small intestine in the control group remained normal.The inflammation cells infiltration and the edema of interstitial substance and epithelials were observed in the endotoxemia and glutamine groups.The pathologic changes in the glutamine group were significantly alleviated when compared with the endotoxemia group.The expression of NF-κB mRNA and protein in the glutamine group was significantly lower than that in the endotoxemia group（P0.01）.The secretion of TNF-α in the glutamine group was significantly lower than that in the endotoxemia group（P0.01）. Conclusions The protective effects of glutamine against intestinal injury may be associated with the down-regulation of intestinal NF-κB mRNA and protein expression and the reduction of the secretion of TNF-α.