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Öğe The effects of enalapril maleate and cold stress exposure on tyrosine hydroxylase activity in some rat tissues(2006) Talas Z.S.; Yurekli M.Enalapril is a highly specific and competitive inhibitor of angiotensin-I converting enzyme (ACE) and thus belongs to the category of ACE inhibitors. The beneficial effects of ACE inhibitors appear to result primarily from the suppression of the plasma renin-angiotensin-aldesterone system. This study was designed to detect the effects of enalapril maleate and cold stress on tyrosine hydroxylase (TH) activity in adrenal medulla, heart and hypothalamus in rat. In cold stress treatment (exposed to 8°C cold for 48 h) TH activity was found to be raised significantly (p < 0.05) in adrenal medulla, hypothalamus and heart tissues. In the adrenal medulla, hypothalamus and heart tissues, TH activity of enalapril maleate treated rats (10 mg kg-1 body weight) group was not raised significantly (p > 0.05). Following intraperitoneal injection of enalapril maleate (10 mg kg-1 body weight) the rats were exposed to 8°C cold for 48 h. After cold stress and enalapril maleate treatment no statistically significant change in tyrosine hydroxylase activity was detected in adrenal medulla, hypothalamus or heart (p > 0.05). The results of our studies show that enalapril maleate blocks the effect of cold stress on the regulation of TH activity. Copyright © 2005 John Wiley & Sons, Ltd.Öğe The effects of phenoxybenzamine on tyrosine hydroxylase (TH) and TH mRNA level in adrenal medulla of sprague dawley rats(1998) Yurekli M.The effects of anti-hipertensive phenoxybenzamine were investigated on tyrosine hydroxylase (TH) enzyme activity and TH mRNA levels. In the present study 5 months male sprague dawley (SD) rats were used. Phenoxybenzamine was injected i.p. as 20 mg/kg which prepared in the 0.9% NaCl and 5% ethanole. TH activity was measured by detecting of formation of 3H2O as a formation of dopa from 3H-tyrosine by radioisotope technique total adrenal RNA was isolated and hybridized with 32P labeled cDNA. TH mRNA was assayed by densitometric scanning of the autoradiograms using a densitometer. TH activity and TH mRNA levels were found to be significantly increased by the effect of phenoxybenzamine (P<0.01).Öğe Malon dialdehyde, nitrite and adrenomedullin levels in patients with premenstrual syndrome(2007) Balat O.; Dikensoy E.; Ugur M.G.; Atmaca R.; Cekmen M.; Yurekli M.Objective: To assess the levels of malon dialdehyde (MDA); a lipid peroxide product, total nitrite; a stabile product of nitric oxide (NO), and adrenomedulin (AM), to determine whether their levels are altered in premenstrual syndrome (PMS) and to search for their possible pathophysiological role in this peculiar syndrome. Study design: Twenty-one patients aged between 28 and 37 years, who had regular menses for at least six previous cycles, and were in general good health condition, were taken into the study. Blood samples were obtained from each patient at the 3rd and 21st day of their menstrual cycles. AM, nitrite, MDA and estradiol levels have been assessed in these samples for each patient. Results: No statistically significant difference in terms of age, parity and body mass index was detected among groups (P > 0.05). Nitric oxide levels were higher on the 3rd day, compared to 21st day in the study group, and this difference was statistically significant (P < 0.05). In the study group, 21st day AM levels were significantly higher when compared to the control group (P < 0.05). Conclusion: Even though various stress symptoms are present in PMS, there is no change in the levels of MDA, an oxidative distress indicator but AM and NO may have a pathophysiological role on this enigmatic disease. © 2006 Springer-Verlag.Öğe 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.Öğe 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.
