鱼油脂肪乳对肠外营养大鼠小肠黏膜紧密连接形态结构的影响

目的:探讨鱼油脂肪乳剂(富含ω-3多不饱和脂肪酸)对肠外营养(PN)大鼠肠上皮细胞紧密连接(TJ)形态和紧密连接蛋白occludin表达的影响。方法:将大鼠随机分为四组,即对照组(正常喂食),PN(禁食5d行PN支持)组,小剂量鱼油治疗(1 ml/kg鱼油静脉注射+PN)组和大剂量鱼油治疗(2 ml/kg鱼油静脉注射+PN)组。观察大鼠术后小肠黏膜上皮细胞TJ形态,以及紧密连接蛋白occludin的表达分布。结果:PN组大鼠治疗5 d后肠上皮细胞TJ结构部分缺失、间隙增宽;大剂量鱼油治疗组TJ形态基本完整,小剂量鱼油治疗组TJ部分缺失。各组occludin蛋白总量无明显差异。提取脂筏组分,发现与对照组比,三个实验组脂筏区域中occludin蛋白表达均明显减少,但大剂量鱼油治疗组较PN组明显升高(P<0.01)。结论:长期PN可导致TJ结构的缺失,脂筏区域紧密连接蛋白occludin表达减少。大剂量鱼油脂肪乳剂可维持occludin蛋白在脂筏区域的表达,保护小肠黏膜细胞TJ的结构和功能。

Effects of fish oil emulsion on intestinal tight junction structure in rats which accepted total parenteral nutrition

Objective: To investigate the effect of fish oil emulsion on tight junction structure(TJ) and tight junction protein occludin expression in rats which accepted total parenteral nutrition(TPN) for 5 days.Methods: 32 SD rats were ramdomly divided into four groups(n=8): control group,TPN group,TPN+fish oil(1 ml/kg) group and TPN+fish oil(2 ml/kg) group.The structure of tight junction was observed by transmission electric microscope.The expression of tight junction protein occludin was detected by Western Blot analysis.Results: Intestinal tight junction structure revealed morphological disruption after TPN for 5 days,and mostly restored by fish oil(2 ml/kg).During this period,total amounts of TJ protein occludin remained unchanged.However,occludin expression in raft microdomains reduced significantly after TPN,fish oil(2 ml/kg) prevented occludin reduction in raft microdomains.Conclusion: Fish oil emulsion could protect intestinal tight junction structure in rats during TPN period,which was partly attributed to its modulation on occludin expression in raft microdomains.