Chen Jiaojiao, Zhang Dianfu, Tan Qingsong, Liu Mengmei, Hu Pengcheng
Key Laboratory of Freshwater Animal Breeding, Ministry of Agriculture, Freshwater Aquaculture Collaborative Innovation Center of Hubei Province, Hubei Provincial Engineering Laboratory for Pond Aquaculture, College of Fisheries, Huazhong Agricultural University, Wuhan, 430070, China.
Fish Physiol Biochem. 2019 Apr;45(2):539-549. doi: 10.1007/s10695-019-00613-w. Epub 2019 Feb 7.
Dietary arginine (Arg) could improve the intestinal structure and absorption of grass carp (Ctenopharyngodon idellus); however, the mechanism of Arg on intestinal morphology improvement was unclear. The present study aimed to explain the possible mechanism of the positive effect of Arg on intestinal epithelial cells of grass carp. An in vitro study was conducted through a primary culture model to assess the growth, cell viability, mRNA expressions of TOR signal pathway, and tight junction proteins of enterocytes after culture in the medium with 6 levels of Arg (0, 0.1, 0.2, 0.5, 1.0, and 2.0 mmol/L). The results showed that 0.5 mmol/L Arg improved the cell number and decreased the lactate dehydrogenase and creatine kinase activities in culture medium (P < 0.05). The alkaline phosphatase activity in cell lysis buffer was depressed by 1 and 2 mmol/L Arg (P < 0.05). The nitric oxide (NO) content showed an increasing trend with the Arg content (P < 0.05), whereas the NO synthase activity showed an opposite trend to NO. TOR expression was higher in 0.2 and 0.5 mmol/L groups, whereas S6K1 expression in 1.0 mmol/L and 2.0 mmol/L groups were lower (P < 0.05). The mRNA expressions of occludin, claudin 3, and claudin c in 0.5 mmol/L group were the highest, while ZO-1 and claudin b expressions were higher in 0.2 and 0.5 mmol/L groups (P < 0.05). This study indicated that Arg enhanced the growth and integrity of intestinal epithelial cells of grass carp through upregulation of mRNA expression of TOR signal pathway and tight junction proteins at an optimal Arg content of 0.2-0.5 mmol/L.
日粮精氨酸（Arg）可改善草鱼（Ctenopharyngodon idellus）的肠道结构和吸收；然而，精氨酸改善肠道形态的机制尚不清楚。本研究旨在解释精氨酸对草鱼肠道上皮细胞产生积极作用的可能机制。通过原代培养模型进行体外研究，以评估在含有6种精氨酸水平（0、0.1、0.2、0.5、1.0和2.0 mmol/L）的培养基中培养后，肠细胞的生长、细胞活力、TOR信号通路的mRNA表达以及紧密连接蛋白。结果表明，0.5 mmol/L精氨酸可增加细胞数量，并降低培养基中的乳酸脱氢酶和肌酸激酶活性（P < 0.05）。1和2 mmol/L精氨酸可降低细胞裂解缓冲液中的碱性磷酸酶活性（P < 0.05）。一氧化氮（NO）含量随精氨酸含量呈增加趋势（P < 0.05），而NO合酶活性与NO呈相反趋势。0.2和0.5 mmol/L组的TOR表达较高，而1.0和2.0 mmol/L组的S6K1表达较低（P < 0.05）。0.5 mmol/L组的闭合蛋白、紧密连接蛋白3和紧密连接蛋白c的mRNA表达最高，而0.2和0.5 mmol/L组的ZO-1和紧密连接蛋白b表达较高（P < 0.05）。本研究表明，在0.2 - 0.5 mmol/L的最佳精氨酸含量下，精氨酸通过上调TOR信号通路和紧密连接蛋白的mRNA表达，增强了草鱼肠道上皮细胞的生长和完整性。
