L-精氨酸对饥饿大鼠内毒素移位和肠黏膜分泌性免疫球蛋白表达的影响

Effect of enteric arginine supplement on intestinal s-IgA expression and endotoxin transiocation in starved rats

目的探讨L-精氨酸对饥饿大鼠内毒素移位和肠黏膜分泌性免疫球蛋白（s—IgA）表达的影响。方法健康雄性SD大鼠90只，3月龄，体重230—270g，随机分为对照组（C组，n=10）、饥饿组（S组，n=40）和L-精氨酸组（L-Arg组，n=40）。C组正常饮食，S组和L-Arg组无饲料供应，自由饮水。L-Arg组以L-精氨酸1．0g·kg^-1·d^-1（溶入2ml蒸馏水中）溶液灌胃。S组和L-Arg组分别于饥饿第3天（T1）、第5天（T2）、第7天（T3）、第9天（T4）随机抽取10只大鼠取门静脉血及小肠组织。测定血浆微量内毒素浓度，免疫组化法检测肠黏膜组织s-IgA的表达。结果与C组相比，S组各时点血浆内毒素浓度升高，小肠黏膜上皮细胞s—IgA表达下调（P〈0．05），L—Arg组各时点血浆内毒素浓度均升高，T1时小肠黏膜上皮细胞s—IgA表达上调，T3和T4时表达下调（P〈0．05）；与S组相比，L-Arg组各相应时点血浆内毒素浓度降低，小肠黏膜上皮细胞s—IgA表达上调（P〈0．05）。结论L-精氨酸可保护饥饿大鼠肠黏膜屏障功能，其机制可能与降低内毒素移位，上调肠黏膜上皮细胞s-IgA表达有关。

Objective To investigate the effects of enteric arginine supplement on endotoxin translocation and intestinal s-IgA expression in starved rats. Methods Ninety male SD rats weighing 230-270 g were randomly divided into 3 groups：normal control group （group C, n = 10）, starvation group （group S, n = 40） and arginine group （group L-Arg, n = 40）. Group C were supplied with normal food, and blood samples from portal vein and intestinal tissue were taken. The animals of group S and group L-Arg were starved with free water supply, and group L-Arg were added with enteric arginine （ 1.0 g· kg^-1· d^-1 ） . Ten rats in each group were killed randomly, and intestinal tissue and blood samples were taken from portal vein on the 3rd,5th,7th, and 9th day after starvation. Plasma concentrations of endotoxin were detected and the expression of secretary immunoglobulin A （s-IgA） was examined by means of immunohistoehemical staining. Results The levels of endotoxin were significantly higher and the expression of s-IgA was significantly lower at all phases after starvation in group S than those in group C separately （P 〈 0.01）. The levels of endotoxin were significantly higher at all phases after starvation in group L-Arg. The expression of s-IgA was higher at T1 and lowed at T3 and T4 in group L-Arg than those in group C （ P 〈 0.05） ; the levels of endotoxin were significantly lower and the expression of s-IgA was higher significantly at all phases after starvation in group L-Arg than those in group S separately （P 〈 0.05 ）. Conclusion L-Arg can protect the function of intestinal mucous membrane barrier in rats by the mechanism of depression of endotoxin translocation and upmodulation of the expression of s-IgA in intestinal mucous membrane.