谷氨酰胺对慢性酗酒大鼠肠道上皮细胞间连接蛋白表达的影响

Effects of glutamine on intercellular junction protein expression of intestinal epithelium in rats with chronic alcohol abuse

目的观察谷氨酰胺对慢性酗酒大鼠肠道上皮紧密连接(TJ)特征性紧密连接蛋白Occludin、ZO-1和粘附连接(AJ)特征性蛋白钙粘连蛋白E表达的影响。方法40只SD大鼠随机分为对照组、谷氨酰胺组(谷氨组)、慢性酗酒处理组(酗酒组)、慢性酗酒并谷氨酰胺组(谷氨+酗酒组),每组10只,并给予相应的处理。用荧光示踪剂测定肠道上皮的渗透性、运用免疫印迹和RT-PCR测定肠道上皮细胞中Occludin、ZO-1和钙粘连蛋白E的蛋白及mRNA表达。结果慢性酗酒导致肠道上皮渗透性明显增高3倍左右(P<0.01);补充谷氨酰胺可以明显改善由慢性酗酒引起的肠道上皮渗透性增高(P<0.05)。免疫印迹和RT-PCR显示在酗酒组的Occludin、ZO-1、钙粘连蛋白E的蛋白和mRNA表达水平均较对照组的表达水平明显下降(P<0.01);在谷氨+酗酒组中Occludin、ZO-1、钙粘连蛋白E的蛋白和mRNA表达水平较酗酒组的表达水平明显增高(P<0.05)。结论慢性酗酒可使TJ分子Occludin、ZO-1和钙粘连蛋白E的mRNA、蛋白表达水平降低导致肠道上皮屏障功能受损,补充谷氨酰胺通过上调上述TJ分子而对慢性酗酒的肠道上皮屏障功能起保护作用。

Objective To investigate the effect of glutamine （Gin） on expression of tight junction （TJ） proteins Occludin and ZO-1, and adherent junction （AJ） protein E-cadherin of intestinal epithdium in rats with chronic alcohol abuse. Methods Forty rats were randomized to control, Gin, alcohol and Gin ＋ alcohol groups. Permeability and expression of Occludin, ZO-1 and E-cadherin mRNA and protein in intestinal epithelium were detected by FITC-dextran （FD4） fluorescence, RT-PCR and immunoblotting, respectively. Results The permeability of intestinal epithdium in alcohol group was approximately 3-fold higher than that in control group （P〈 0.01 ）, but the permeability change was reversed by Gln supplementation （P 〈 0, 05 ）. The expression of Occludin, ZO-1 and E-cadherin rnRNA and protein was significantly lower in alcohol group than that in control group （P〈 0.01）, whereas their expression in Gin ＋ alcohol group was superior to that in alcohol group （P〈 0.05）. Conclusion Chronic alcohol abuse can impair the barrier function of intestinal epithelium by down-expression of Occludin, ZO-1 and E-cadherin, which may be improved by Gin supplementation.