Protective role of heme oxygenase-1 on trinitrobenzene sulfonic acid-induced colitis in rats.
Preliminary studies showed that the inducible form of heme oxygenase (HO-1) was induced and played a protective role in the process of inflammation. The present study investigated the possible role of HO-1 in 2,4,6-trinitrobenzene sulfonic acid (TNBS)-induced colitis in rats. We measured HO-1 activity in TNBS-induced colitis in rats and analyzed the severity of colitis along with altered HO activity by assessing lesion area and myeloperoxidase activity. HO-1 mRNA and protein expressions were determined at different time points after TNBS induction. Free radical production and inducible nitric oxide synthase (iNOS), which participate in oxidative injury, were also assayed. HO activity and HO-1 gene expression increased markedly after TNBS induction. Administration with tin mesoporphyrin (SnMP), a HO inhibitor, potentiated the colonic damage along with a reduction in HO-1 activity. Furthermore, the reduction of HO-1 expression by SnMP also enhanced reactive oxygen species and iNOS expression, both of which were dramatically increased after the TNBS enema. L-Arginine pretreatment further aggravated the injurious action of SnMP. Our results indicate that HO-1 plays a protective role in the colonic damage induced by the TNBS enema, and the preventive effects probably result from decreased free radical production and inhibition of iNOS expression in colonic tissues.
Wang
W P
WP
Department of Pharmacology, Faculty of Medicine, The University of Hong Kong, Hong Kong, People's Republic of China.
Guo
X
X
Koo
M W
MW
Wong
B C
BC
Lam
S K
SK
Ye
Y N
YN
Cho
C H
CH
D000818:Animals; D003093:Colitis, Ulcerative / Q000139:chemically induced / Q000201:enzymology* / Q000473:pathology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006419:Heme Oxygenase (Decyclizing) / Q000096:biosynthesis / Q000235:genetics / Q000276:immunology / Q000502:physiology*; D051547:Heme Oxygenase-1; D007150:Immunohistochemistry; D008163:Luminescent Measurements; D008297:Male; D008665:Metalloporphyrins / Q000494:pharmacology; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors; D052247:Nitric Oxide Synthase Type II; D009195:Peroxidase / Q000378:metabolism; D012333:RNA, Messenger / Q000096:biosynthesis; D051381:Rats; D017207:Rats, Sprague-Dawley; D017382:Reactive Oxygen Species / Q000378:metabolism; D014302:Trinitrobenzenesulfonic Acid
D004791:Enzyme Inhibitors; D008665:Metalloporphyrins; D012333:RNA, Messenger; D017382:Reactive Oxygen Species; C055421:tin mesoporphyrin; D014302:Trinitrobenzenesulfonic Acid; D009195:Peroxidase; D019001:Nitric Oxide Synthase; D052247:Nitric Oxide Synthase Type II; C496318:Nos2 protein, rat; D006419:Heme Oxygenase (Decyclizing); D051547:Heme Oxygenase-1; C105245:heme oxygenase-2