脓毒症大鼠小肠上皮PepT1的表达变化及其与Ghrelin的相关性研究

Expression of PepT1 in the small intestinal epithelium of rats with sepsis and its correlation with ghrelin

目的探讨脓毒症对大鼠小肠上皮短肽载体1(PepT1)表达的影响以及PepT1表达与Ghrelin水平的关系。方法雄性SD大鼠48只,随机分为对照组(n=8)和脓毒症组(n=40)。脓毒症组大鼠采用盲肠结扎穿孔法(CLP)建立脓毒症模型,模型建立后4、8、12、16、20h分别处死8只小鼠,留取小肠黏膜和全血标本。光镜下观察空肠黏膜的病理学变化,ELISA方法检测血清及肠黏膜Ghrelin水平,Real-time PCR及Western Blotting分别检测肠上皮PepT1 mRNA及蛋白的表达。结果 CLP所致脓毒症导致大鼠小肠黏膜明显损伤,主要表现为黏膜短缩、脱落,毛细血管扩张出血和溃疡形成。脓毒症8、12、16、20h各亚组小肠上皮PepT1 mRNA表达水平均较对照组明显下降(P<0.05),但各亚组间表达水平无明显差异(P>0.05);脓毒症12、16、20h亚组小肠上皮PepT1蛋白表达较对照组及脓毒症4h和8h亚组减少(P<0.05);血清和肠黏膜Ghrelin水平均在建模4h时达高峰,之后逐渐下降,与对照组比较差异均有统计学意义(P<0.05);血清和肠黏膜Ghrelin水平与PepT1蛋白表达均呈正相关(r=0.792、r=0.756,P<0.001)。结论脓毒症时Ghrelin表达水平在短暂上升后显著下降,与小肠上皮PepT1蛋白表达密切相关,可能是导致脓毒症时小肠上皮PepT1表达下降的原因之一。

Objective To investigate the effect of sepsis on the changes in PepT1 expression in the small intestinal epithelium of rats,and its correlation with ghrelin.Methods Forty-eight male SD rats were randomly divided into control group（n=8） and sepsis group（n=40）.The sepsis model was reproduced with cecal ligation and puncture（CLP）.The small intestinal mucosa and blood samples were obtained 4,8,12,16 and 20h after CLP.The pathologic changes in the jejunal mucosa were investigated under light microscope.The level of ghrelin in the serum and intestinal mucosa was detected by ELISA.The expressions of PepT1 mRNA and protein were determined by Western blotting and real-time PCR.Results In the sepsis animals,intestinal mucosa showed marked injury with shortening and shedding of the epithelium,detachment of the lamina propria,hemorrhage and ulceration.Compared with control group,the expression of PepT1 mRNA in sepsis group significantly decreased 8,12,16 and 20h after CLP（P0.05）.But there were no differences among the subgroups（P0.05）.The expressions of PepT1 protein 12,16 and 20h after CLP were significantly lowered compared with that of control group and 4,8h after CLP（P0.05）.In the sepsis group,the Ghrelin level in the serum and intestinal mucosa reached its peak 4h after CLP,then it significantly decreased as compared with control group（P0.05）.Ghrelin level in both serum and intestinal mucosa was positively related to PepT1 protein（r=0.792,r=0.756,P0.001）.Conclusion In sepsis rats,the expression of ghrelin decreased signiicantly ater a brief increase,which was positively correlated with PepT1 protein level in the intestinal epithelium,and may be the cause of the decrease of PepT1 expression in the intestinal epithelium.