title: Effects of simulated weightlessness on tight junction protein occludin and Zonula Occluden-1 expression levels in the intestinal mucosa of rats.
abstract: 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.
authors.affiliation: PLA Postgraduate Medical School, Beijing, 100853, China.|Department of Gastroenterology and Research Center of Aeropathy, General Hospital of Air Force, PLA, Beijing, 100036, China.
authors.forename: Chen
authors.initials: C
authors.lastname: Ying
authors.affiliation: Department of Gastroenterology and Research Center of Aeropathy, General Hospital of Air Force, PLA, Beijing, 100036, China.
authors.forename: Yang
authors.initials: Y
authors.lastname: Chunmin
authors.affiliation: Department of Gastroenterology, General Hospital of PLA, Beijing, 100853, China. Liuqs301@sina.com.
authors.forename: Liu
authors.initials: L
authors.lastname: Qingsen
authors.affiliation: Department of Gastroenterology, General Hospital of PLA, Beijing, 100853, China.
authors.forename: Guo
authors.initials: G
authors.lastname: Mingzhou
authors.affiliation: Department of Gastroenterology, General Hospital of PLA, Beijing, 100853, China.
authors.forename: Yang
authors.initials: Y
authors.lastname: Yunsheng
authors.affiliation: Department of Gastroenterology and Research Center of Aeropathy, General Hospital of Air Force, PLA, Beijing, 100036, China.
authors.forename: Mao
authors.initials: M
authors.lastname: Gaoping
authors.affiliation: Department of Gastroenterology and Research Center of Aeropathy, General Hospital of Air Force, PLA, Beijing, 100036, China.
authors.forename: Wang
authors.initials: W
authors.lastname: Ping
mesh_terms: D000818:Animals; D019417:Hindlimb Suspension; D007413:Intestinal Mucosa / Q000378:metabolism*; D008297:Male; D062793:Occludin / Q000235:genetics / Q000378:metabolism*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D018474:Weightlessness Simulation; D062826:Zonula Occludens-1 Protein / Q000235:genetics / Q000378:metabolism*
chemical_list: D062793:Occludin; C568987:Ocln protein, rat; D012333:RNA, Messenger; C569044:Tjp1 protein, rat; D062826:Zonula Occludens-1 Protein