THE ROLE OF METHYLATED ADRENOMEDULLIN IN ENZYMATIC ANTIOXIDANT DEFENSE RESPONSE TO COLD STRESS

The aim of our study was to investigate the effects of methylated adrenomedullin (met-AdM) on some antioxidant enzymes, such as catalase (CAT), glutathione peroxidase (GSH-P-X) and superoxide dismutase (SOD) in rat kidney and heart tissues after cold stress treatment. Male Wistar rats were divided into 4 groups (control, met-AdM, cold stress and cold stress + met-AdM treatments). The rats were kept at room temperature, exposed to a 16/8-hours light/dark cycle. The rats were maintained at ad libitum (free) feeding habit. In met-AdM treated group, animals received intraperitoneal injection of met-AdM (2 mg/g body weight) once a day during a week. For the cold stress exposure, the rats were kept in separate cages at 10 degrees C for a week. Control group rats were kept at laboratory conditions. CAT, GSH-P-X and SOD enzyme activities were investigated in kidney and heart tissues. In kidney tissue compared to control, CAT and GSH-P-X enzyme activity was decreased but SOD was increased in met-AdM-treated group. In met-AdM+cold stress group, only the SOD enzyme activity was significantly increased but CAT and GSH-P-X decreased. SOD and GSH-P-X enzyme activities were increased by cold stress but CAT was decreased in kidney. In heart tissue, CAT and GSH-P-X activities were decreased but SOD was increased in met-AdM-treated group compared to control. All enzyme activities were decreased in met-AdM+cold stress group as well as by cold stress in heart, with regard to control. Cold stress can disrupt the balance in an oxidant/antioxidant system and cause oxidative damage to kidney and heart tissues by altering the enzymatic and non-enzymatic antioxidant status. We can suggest that met-AdM has possible roles in regulation of stress but we need further studies revealing responses of met-AdM in different tissues.