The investigation of the effect of adrenomedullin on the benzo (A) pyrene treated rats in some rat tissues

Adrenomedullin (AdM), a 52-amino acid ringed-structure peptide with Cterminal amidation, was originally isolated from human pheochromocytoma. AdM acts as a circulating hormone as well as elicits multiple biological activites in a paracrine or autocrine manner. Recently, it has been reported that AdM may possess antioxidant properties and protects cells from oxidative damage. Polycyclic aromatic hydrocarbons (PAHs), environmental contaminants, cause oxidative stress in organisms. Some PAHs such as B(a)P cause carcinogenic effects in organisms. B(a)P, found in air, water, soil and food, is a oxidative stress source for organisms. In this study, the effect of AdM administration was investigated on the antioxidant system in the heart, kidneys, liver and lungs of rats exposed to B(a)P. Thirty male Wistar rats were randomly assigned to one of five groups: control group, oil group, AdM group, B(a)P group, B(a)P+AdM group. B(a)P was dissolved in corn oil and a single 50 mg/kg body weight dose injected intraperitonally. Oil group animals received 50 mg/kg b.w. corn oil only. In AdM-treated group animals received intraperitoneal (i.p.) injection of AdM (2 ?g/kg body weight) for two week during 7th and 8th weeks. The activities of superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GSH-Px) and the level of total glutathione and malondialdehyde (MDA) were determined in the tissues of rats. Also, nitric oxide (NO) and AdM levels and histological examinations in the tissues were determined. In this study, B(a)P treatment generally decreased antioxidant enzyme activities and caused histological changes. B(a)P+AdM treatment generally restored antioxidant system and cause ameliorative effects in histopathological parameters in kidneys and heart, but no beneficial effects observed in liver and lungs. In the B(a)P administrated groups AdM levels were increased. When the results are taken together adrenomedullin treatment has both ameliorative and deletiorous effects on biochemical and histological parameters. These different experimental results may be due to tissue specifity, treatment of AdM concentration and duration. KEYWORDS: Adrenomedullin, Benzo(a)pyrene, Nitric oxide, Oxidative stress