Ying Chen, Chunmin Yang, Qingsen Liu, Mingzhou Guo, Yunsheng Yang, Gaoping Mao, Ping Wang
PLA Postgraduate Medical School, Beijing, 100853, China.
Department of Gastroenterology and Research Center of Aeropathy, General Hospital of Air Force, PLA, Beijing, 100036, China.
J Huazhong Univ Sci Technolog Med Sci. 2011 Feb;31(1):26-32. doi: 10.1007/s11596-011-0145-5. Epub 2011 Feb 19.
This study investigated the tight junction (TJ) protein expression of the intestinal mucosa in a rat tail-suspension model under simulated weightlessness. Twenty-four Wistar rats were randomly divided into three groups: CON group (n=8), control; SUS-14 d group (n=8), tail-suspension for 14 days; SUS-21 d group (n=8), tail-suspension for 21 days. Occludin and Zonula Occluden-1 (ZO-1) expression levels were determined by immunohistochemical analysis and mRNA fluorescent quantitative PCR. Plasma levels of diamine oxidase (DAO) and d-lactate were determined using enzymatic spectrophotometry. Immunohistochemical results for occludin and ZO-1 showed disruption of the TJs in the intestinal mucosa in SUS-14 d and SUS-21 d groups. The expression levels of occludin and ZO-1 in SUS-21 d group were lower than those in SUS-14 d group, and significantly lower than those in CON group (Occldin: 0.86±0.02 vs 1.01±0.03 vs 1.63±0.03 and ZO-1: 0.82±0.01 vs 1.00±0.02 vs 1.55±0.01, P<0.01). Moreover, the levels of plasma DAO and d-lactate in SUS-21 d group were higher than those in SUS-14 d group, and significantly higher than those in CON group (DAO: 27.58±0.49 vs 20.74±0.49 vs 12.94±0.21 and d-lactate: 37.86±0.74 vs 28.26±1.01 vs 17.76±0.91, P<0.01). There were significant negative correlations between occludin or ZO-1 expression levels and DAO (r (2)=0.9014, r (2)=0.9355, P<0.01) or d-lactate levels (r (2)=0.8989, r (2)=0.9331, P<0.01). Occludin and Zo-1 were reduced in intestinal mucosa both in mRNA and protein levels in the rat tail-suspension model. The significant negative correlations between expression levels of TJs and plasma levels of DAO or d-lactate support the hypothesis that intestinal permeability is increased due to a decrease in TJ protein expression during tail-suspension from 14 days to 21 days.
本研究在模拟失重条件下，对大鼠尾部悬吊模型中肠黏膜紧密连接（TJ）蛋白的表达进行了研究。将24只Wistar大鼠随机分为三组：CON组（n = 8），对照组；SUS - 14 d组（n = 8），尾部悬吊14天；SUS - 21 d组（n = 8），尾部悬吊21天。采用免疫组织化学分析和mRNA荧光定量PCR法测定闭合蛋白和紧密连接蛋白1（ZO - 1）的表达水平。用酶分光光度法测定血浆中二胺氧化酶（DAO）和d - 乳酸的水平。闭合蛋白和ZO - 1的免疫组织化学结果显示，SUS - 14 d组和SUS - 21 d组肠黏膜中的紧密连接遭到破坏。SUS - 二十一天组中闭合蛋白和ZO - 1的表达水平低于SUS - 14 d组，且显著低于CON组（闭合蛋白：0.86±0.02 vs 1.01±0.03 vs 1.63±0.03；ZO - 1：0.82±0.01 vs 1.00±0.02 vs 1.55±0.01，P<0.01）。此外，SUS - 21 d组血浆中DAO和d - 乳酸的水平高于SUS - 14 d组，且显著高于CON组（DAO：27.58±0.49 vs 20.74±0.49 vs 12.94±0.21；d - 乳酸：37.86±0.74 vs 28.26±1.01 vs 17.76±0.91，P<0.01）。闭合蛋白或ZO - 1表达水平与DAO（r² = 0.9014，r² = 0.9355，P<0.01）或d - 乳酸水平（r² = 0.8989，r² = 0.9331，P<0.01）之间存在显著负相关。在大鼠尾部悬吊模型中，肠黏膜中闭合蛋白和ZO - 1在mRNA和蛋白水平均降低。紧密连接表达水平与血浆中DAO或d - 乳酸水平之间的显著负相关支持了以下假设：在14天至21天的尾部悬吊过程中，由于TJ蛋白表达减少，肠道通透性增加。
