The effect of alpha-melanocyte stimulating hormone on colonic inflammationin the rat

The effect of cu-melanocyte stimulating hormone (alpha -MSH) on colonic inf lammation in the rat. In this study, we investigated the effects of alpha - MSH administration on trinitrobenzene sulfonic acid-induced colitis and the role of nitric oxide and prostaglandins in this response. (alpha -MSH trea tment (25 mug/rat, intraperitoneally; twice daily for 3 days) reduced the c olonic macroscopic lesions compared to untreated ones in both acute and chr onic colitis groups. This effect was reversed by pretreatment with the nitr ic oxide donor, sodium WP (4 mg/kg, intravenously) or cyclooxygenase-l sele ctive antagonist indomethacin (5 mg/kg, subcutaneously) in the acute group and with the cyclooxygenase-2 selective antagonist nimesulide (3 mg/kg, sub cutaneously) in the chronic group. alpha -MSH had no effect on colonic wet weight and myeloperoxidase acitivity compared to the untreated colitis grou p. However, protein oxidation was markedly elevated in the alpha -MSH-treat ed group compared to untreated ones. Nitroprusside and indomethacin reverse d the effect of alpha -MSH on macroscopic lesions in the acute groups, wher eas nimesulide showed a similar effect in the chronic group. In conclusion, the results of our study show a protective role of alpha -MSH on colonic l esions which partially involves nitric oxide and prostaglandins. (C) 2000 E lsevier Science Inc. All rights reserved.