异亮氨酸调控大鼠小肠黏膜形态和结构的作用机制  

The regulatory mechanism of isoleucine on the mucosal morphology and structure of rat intestine

作　　者：任曼[1] 杨亚南 赵春芳 车传燕[1] 李升和[1] Man Ren;Ya’nan Yang;Chunfang Zhao;Chuanyan Che;Shenghe Li(Anhui Provincial Key Laboratory of Animal Nutritional Regulation and Health,College of Animal Science,Anhui Science and Technology University,Fengyang 233100,China)

机构地区：[1]安徽科技学院动物科学学院,动物营养调控与健康安徽省重点实验室,凤阳233100

出　　处：《科学通报》2022年第6期520-527,共8页Chinese Science Bulletin

基　　金：国家自然科学基金(31672502,3151968);安徽省自然科学基金青年项目(1608085QC72);安徽省科技重大专项计划(17030701004,201903a06020002);安徽省高校拔尖人才学术项目(gxbjZD2020080)资助。

摘　　要：作为动物体重要的必需氨基酸,异亮氨酸除了作为蛋白合成底物外,还可促进肠道的吸收功能和屏障功能,但其作用机制尚不清楚.本研究通过体内动物试验和体外细胞试验探究了异亮氨酸对肠道黏膜结构和功能的可能作用机制.试验选用80只远交群大鼠,随机分为4组,饮水添加不同浓度异亮氨酸(0、0.5、2.5和5 mg/mL),试验期为28 d,测定大鼠小肠各段组织结构和空肠中紧密连接蛋白表达水平.体外试验选用大鼠空肠上皮细胞系IEC-6并用不同浓度异亮氨酸处理,通过噻唑兰测定细胞活力,流式细胞术测定细胞的周期和凋亡情况,Western blot分析细胞中紧密连接蛋白表达情况.结果表明,饮水中添加2.5 mg/mL异亮氨酸显著提高了小肠的绒毛高度和绒毛高度隐窝深度比,显著降低了隐窝深度,并显著提高空肠紧密连接表达;适宜浓度异亮氨酸显著促进了IEC-6细胞的增殖并提高细胞中紧密连接蛋白表达量,而高浓度异亮氨酸呈现抑制作用.综上,异亮氨酸可改善小肠的组织结构,尤其促进绒毛生长并提高吸收表面积,其可能作用机制是适宜异亮氨酸可促进小肠上皮细胞的增殖并降低凋亡,进而增大了绒毛的高度;异亮氨酸提高了上皮细胞中紧密连接蛋白的合成,进而促进大鼠空肠的黏膜屏障功能.本研究为异亮氨酸在改善人和动物肠道健康方面的研究和应用提供理论基础.The intestinal surface faces the challenging task of protecting a vast surface area while maintaining homeostasis with abundant commensal microorganisms and preventing pathogen invasion.The mucosal epithelial cells of the intestine and its cell tight junctions constitute the mechanical barrier,which significantly maintains the integrity and function of the intestine.For humans and animals,small intestinal digestion and absorption capacity for nutrients are often severely impaired,which confirms that maintaining the morphological integrity of the intestinal villi is very important.As an essential amino acid in animals,isoleucine can improve intestinal absorption and barrier function,as well as participates in protein synthesis and serves as an energy source for intestinal epithelial cells.In the current study,we attempted to determine further the function of isoleucine and explored the possible mechanism of isoleucine on the structure and function of intestinal mucosa through in vivo and in vitro experiments.For in vivo experiments,a total of 80 SD rats were selected and randomly divided into 4 groups.Different concentrations of isoleucine(0,0.5,2.5,and 5 mg/mL)were added to the drinking water of these groups of mice,and the experimental period was settled for 28 d.Further,the morphological structure and the expression level of tight junction protein in the rat intestine were measured.For in vitro study,rat jejunal epithelial cell line IEC-6 was treated with different concentrations of isoleucine(0,0.1,0.5,2.5,12.5,and 25.0 mmol/L).Cell viability was measured by MTT,while cell cycle and apoptosis were measured by flow cytometry,and tight junction protein expression in cells was analyzed by Western blot.The results revealed that 2.5 mg/kg isoleucine supplemented in rat drinking water significantly increased the ratio of villus height to villus crypt depth;for example,improved villus height and reduced crypt depth of duodenum,jejunum,and ileum(P<0.05)were observed.Moreover,2.5 mg/kg isoleucine treatment also increas

关 键 词：异亮氨酸 小肠黏膜 紧密连接蛋白 细胞周期 细胞凋亡 

分 类 号：S816[农业科学—饲料科学]