脓毒症大鼠小肠上皮短肽载体生物学功能的变化

Change of PepT1 biological functions of the small intestinal epithelial of rats with sepsis

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 change of PepT1 expression and functions of the small intestinal epithelial of rats with sepsis. Methods： Sixty male SD rats were randomized into control group（n--10） ,sepsis group（n =50）. The model of sepsis was made with cecal ligation and puncture （CLP）. The small intestinal mucosas were harvested 4,8,12,16 h and 20 h after CLP, and the blood samples were collected. The intestinal histological was investigated. Serum and intestinal mucosas TNF-c~ and IL-I[3 were detected with Elisa. In addition, Realtime PCR and Western-blot were used to detect PepT1 mRNA expression and PepT1 protein expression levels respectively. And the uptake of PepT1 of small intestinal epithelial cells was measured with high performance liquid chromatography. Results： In the sepsis animals,intestinal mucosa showed marked injury with shortening and shedding of mucosa, detachment of the lamina propria, hemorrhage and ulceration. In the sepsis group, serum and intestinal mucosas TNF-α and IL-1 β levels reached its peak in 4h after CLP, then significantly decreased comparing to control group（P 〈0.05）. The PepT1 mRNA expression levels in 8h,12h, 16h and 20h after CLP weresignificantly decreased comparing to control group （ P 〈 0.05 ）. The PepT1 protein expression levels in 12h,16h and 20h after CLP were significantly decreased comparing to control group and the 4h,8h after CLP（P 〈 0.05 ）. The uptake of PepT1 in the sepsis of 12h, 16h and 20h groups were significantly decreased compared to control group and sepsis of 4h and 8h groups （P 〈 O. 05 ）. Conclusion ： The PepT1 mRNA and protein expression levels with sepsis are significantly decreased, which downrugulated the biological functions of small intestinal epithelial cell.