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Protective effect of melatonin in acetic acid induced colitis in rats
Author(s) -
Nosál'ová Viera,
Zeman Michal,
Černá Silvia,
Navarová Jana,
Zakálová Monika
Publication year - 2007
Publication title -
journal of pineal research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.881
H-Index - 131
eISSN - 1600-079X
pISSN - 0742-3098
DOI - 10.1111/j.1600-079x.2007.00428.x
Subject(s) - melatonin , colitis , acetic acid , medicine , endocrinology , chemistry , pharmacology , biology , biochemistry
Possible protective effects of exogenous melatonin on colonic inflammation were studied in rats. Colitis was induced by intracolonic (i.c.) instillation of 4% acetic acid (AA) and the resulting injury was assessed after 1 and 48 hr. Diffuse hyperemia and bleeding with erosions and ulcerations were observed in the colons of vehicle‐treated rats. Melatonin administered in doses of 5 and 10 mg/kg reduced significantly the extent of gross mucosal damage after intraperitoneal as well as i.c. dosing. The inflammation induced increase in colonic wet weight was also reduced by melatonin treatment. In the early phase of colonic inflammation (60 min), melatonin partly prevented the decrease of reduced glutathione (GSH) content and limited lysosomal enzyme, N ‐acetyl‐glucosaminidase and cathepsin D, activities induced by AA, with no changes in proteins or acid phosphatase activity. Increase of myeloperoxidase activity (MPO) caused by colonic inflammation was prevented by melatonin given i.c. As observed 48 hr after AA exposure, there was no difference between the effect of vehicle and melatonin on the content of GSH. Colitis did not influence the melatonin content of the colon. After administration of exogenous melatonin, plasma, pineal and gut melatonin tended to increase. The results indicate that melatonin participates in various defense mechanisms against colonic inflammatory processes by preserving the important endogenous antioxidant reserve of GSH, by preventing lysosomal enzyme disruption, by inhibiting enhanced MPO activity, thus reducing the extent of colonic damage, mainly in the early phase of colitis.