The investigation of the effects of heavy metal and adrenomedullin treatment on the antioxidant defense systems in some rat tissues

Supervisor: Prof. Dr. Muhittin YÜREKLİ Adrenomedullin (AdM) is a multifunctional peptide, originally isolated from human pheochromocytoma but later found to be ubiquitously expressed. The most characteristic biological activity of AdM is its very powerful hypotensive activity. AdM acts as a circulating hormone and elicits multiple biological activities. Recently, it has been reported that AdM may possess antioxidant properties and protect cells from oxidant damage. In this study, we investigated the effect of AdM administration on the antioxidant system in liver, lungs and kidneys of rats exposed to cadmium and lead. Thirty-six female Wistar rats were divided into six groups: Control group (C), adrenomedullin group (AdM), cadmium (Cd), cadmium + adrenomedullin (Cd + AdM), lead (Pb) and lead + adrenomedullin Pb + AdM) group. In Cd and Pb-treated groups, animals were exposed to cadmium and lead drinking water containing 100 ppm CdCl2 and 250 ppm PbCl2 for four weeks, respectively. AdM-treated group, animals received intraperitoneal (i.p.) injection of AdM (3000 ng/kg body weight) in the third week of heavy metal treatment for one week. The activities of catalase (CAT), glutathione peroxidase (GSH-Px) and superoxide dismutase (SOD), the level malondialdehyde (MDA) and histopathological changes were determined in the tissues of rats. Also, cadmium and lead levels in the tissues were determined by atomic absorption spectrometer (AAS). In conclusion, AdM treatment decreased lipid peroxidation and tissue Pb levels in liver and lung, and also reduced hepatic damage in Pb exposed rats. But in Cd exposed rats, ameliorative effect of AdM treatment was not observed in these parameters. Moreover, AdM treatment compensated some antioxidant enzyme activities in both Cd and Pb exposed rats. When the results are taken together, it can be concluded that AdM may have protective or compensating effect in cadmium and lead toxicity. KEYWORDS: Adrenomedullin, antioxidant enzymes, lipid peroxidation, cadmium, lead, rat