Effect of adrenomedullin administration on acetic acid-induced colitis in rats.

Adrenomedullin (AM) administered intracolonically ameliorated the severity of acetic acid-induced colonic ulceration in rats. Ulcers were induced by subserosal injection of acetic acid into the colon. AM-treated group was administered 0.25-1.0 microg of AM in 0.5 ml of saline intracolonically once a day; the control group received only saline. AM administration dose-dependently and significantly reduced the size of the ulcerative lesions, the associated edema, and the infiltration of the affected area by inflammatory cells. AM also reduced tissue levels of interleukin-6, but not interferon-gamma. AM reduces the severity of acetic acid-induced colitis in rats, probably by inhibiting the production and/or release of Th-2 cell-derived factors such as interleukin-6.