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    The role of methylated adrenomedullin in enzymatic antioxidant defense response to cold stress
    (2010) Yildirim N.C.; Yurekli M.
    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-Px) 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 °C for a week. Control group rats were kept at laboratory conditions. CAT, GSH-Px and SOD enzyme activities were investigated in kidney and heart tissues. In kidney tissue compared to control, CAT and GSH-Px 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-Px enzyme activities were increased by cold stress but CAT was decreased in kidney. In heart tissue, CAT and GSH-Px 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.
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    Stress-induced changes in tyrosine hyroxylase enzyme activity and adrenomedullin levels in rat hypothalamus, adrenal medulla and heart tissues
    (Academic Journals Inc., 2010) Yildirim N.C.; Yurekli M.
    In this study, it was aimed to investigate the effects of chronic cold stress on adrenomedullin levels and tyrosine hydroxylase enzyme activities in some rat tissues. In this study, 12 female Sprague Dawley rats weighing 200 to 250 g were used. Rats were housed under diurnal lighting conditions (12-12 h) with free access to food and water. For this study, rats were divided into two groups, namely control group and cold stress treated group. Adrenomedullin levels were measured by high performance liquid chromatography. Tyrosine hydroxylase enzyme activities was spectrometrically measured. Tyrosine hydroxylase activity was found to be increased significantly (p<0.05) in adrenal medulla, hypothalamus and heart tissues depending on cold stress treatment. Adrenomedullin levels were determined to be decreased in the cold stress treatment group. The differences of between control and cold stress treatment groups were significant (p<0.05). The results suggested that adrenomedullin may play a possible role in adaptation to stress. Exposure to cold increases the synthesis and release of catecholamines. Tyrosine hydroxylase is the rate limiting step in the biosynthesis of catecholamines for this reason cold stress increased tyrosine hyroxylase enzyme activities. Further studies are needed to reveal correlation between adrenomedullin, tyrosine hydroxylase and cold stress. © 2010 Academic Journals Inc.