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目的:探讨脓毒症对大鼠小肠上皮短肽载体(PepT1)的表达和功能变化影响。方法:将60只大鼠分为对照组(n=10)和脓毒症组(n=50),采用盲肠结扎穿刺术(CLP)动物模型。模型建立后4、8、12、16和20 h留取血标本和小肠黏膜,行肠黏膜病理检查,用Elisa方法检测血清、肠黏膜肿瘤坏死因子-α(TNF-α)和白细胞介素-1β(IL-1β)水平,实时定量PCR和蛋白印迹法分别检测肠上皮PepT1 mRNA和蛋白表达。采用高效液相色谱法检测PepT1的摄取功能。结果:CLP所致的脓毒症大鼠小肠黏膜明显损伤,表现为黏膜短缩、脱落,毛细血管扩张出血和溃疡形成。血清和肠黏膜TNF-α、IL-1β水平均在建模4 h时达高峰,之后逐渐下降,显著高于对照组(P<0.05)。脓毒症8、12、16和20 h组小肠上皮PepT1 mRNA表达水平较对照组明显下降(P<0.05),PepT1蛋白表达也较对照组显著减少(P<0.05)。脓毒症12、16和20 h组小肠上皮PepT1对底物的摄取功能较对照组明显下降(P<0.05),摄取量也较脓毒症4 h和8 h组明显下降,差异均有统计学意义(P<0.05)。结论:CLP所致的脓毒症大鼠小肠上皮PepT1 mRNA和蛋白表达明显下降,机体在基因和蛋白水平下调了肠上皮PepT1生物学功能。
Objective: To investigate the effect of sepsis on the expression and function of rat intestinal epithelial short peptide carrier (PepT1). Methods: Sixty rats were divided into control group (n = 10) and sepsis group (n = 50), and cecal ligation and puncture (CLP) animal model was used. Blood samples and small intestinal mucosa were collected at 4, 8, 12, 16, and 20 h after model establishment, and pathological examination of intestinal mucosa was performed. Serum and intestinal mucosal tumor necrosis factor-α (TNF-α) and interleukin- 1β (IL-1β) levels were detected by real-time quantitative PCR and Western blotting respectively. PepT1 uptake was detected by high performance liquid chromatography. Results: The small intestinal mucosa of rats with sepsis induced by CLP was obviously damaged, which manifested as mucosal shortening, shedding, capillary dilation and ulcer formation. The levels of TNF-α and IL-1β in serum and intestinal mucosa peaked at 4 h after modeling, and then decreased gradually, which was significantly higher than that of the control group (P <0.05). The expression of PepT1 mRNA in intestinal epithelium of sepsis group was significantly lower than that of the control group (P <0.05) at 8, 12, 16 and 20 h, and the protein expression of PepT1 was also significantly decreased (P <0.05). Sepsis 12, 16 and 20 h group intestinal epithelial PepT1 substrate uptake function was significantly lower than the control group (P <0.05), the intake of sepsis than 4 h and 8 h group were significantly decreased, the differences were statistically Significance (P <0.05). CONCLUSION: PepT1 mRNA and protein expression in the intestinal epithelium of CLP-induced septic rats was significantly decreased, and the biological function of PepT1 in intestinal epithelial cells was down-regulated by the gene and protein level.