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    Effect of pentoxifylline on antioxidant status of healthy and endotoxemic New Zealand white rabbits
    (VETERINARNI A FARMACEUTICKA UNIVERZITA BRNO, 2005) Keskin, E; Oztekin, E; Col, R; Sivrikaya, A; Uney, K; Yazar, E
    In this study, effect of pentoxifylline on antioxidant status of healthy and endotoxemic rabbits was investigated. Endotoxemia was induced with E. coli lipopolysaccharide in New Zealand white rabbits. Forty rabbits were randomly divided into four equal groups. Group 1 served as control. Animals in Group 2 were given lipopolysaccharide (400 mu g/kg) intravenously, in Group 3 pentoxifylline (50 mg/kg) was injected intraperitoneally. In Group 4; pentoxifylline (50 mg/kg intraperitoneally) and lipopolysaccharide (400 mu g/kg, intravenously) were injected simultaneously. Animals were killed, and liver, heart and kidney samples were taken at 6 hours after administrations. Malondialdehyde, superoxide dismutase, glutathione peroxidase and reduced glutathione levels of heart, liver and kidney tissues were measured. Lipopolysaccharide caused significant increases (p < 0.05) in hepatic malondialdehyde, and cardiac, hepatic and renal glutathione peroxidase activities. It however, caused significant (P < 0.05) decrease in hepatic superoxide dismutase activity when compared to control group. Pentoxifylline caused significant (p < 0.05) increases of cardiac and hepatic malondialdehyde levels, cardiac superoxide dismutase and renal glutathione peroxidase activities, and cardiac, hepatic and renal reduced glutathione levels when compared to control group. As a result, pentoxifylline has no exactly beneficial effect on the antioxidant status of healthy and endotoxaemic New Zealand white rabbits at the administered dose and route. Although it was stated that pentoxifylline may be beneficial in endotoxaemia, its antioxidant effect may be dependent on dose, administration route and animal species. For this reason, when pentoxifylline is used in endotoxaemia, a treatment protocol should be done for each animal species.
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    Effects of different doses of tilmicosin on malondialdehyde and glutathione concentrations in mice
    (VETERINARNI A FARMACEUTICKA UNIVERZITA BRNO, 2004) Yazar, E; Oztekin, E; Sivrikaya, A; Col, R; Elmas, M; Bas, AL
    The aim of this study was to follow the effects of different doses of tilmicosin on malondialdehyde and reduced glutathione levels of heart and liver, and on selected haematological indices. Forty male Balb/C mice were used throughout the experiment. They were divided into four groups (n = 10), and injected subcutaneously as follows: Group I (control), with isotonic saline solution, Group 2 with 25 mg/kg body weight of tilmicosin, Group 3 with 50 mg/kg, and Group 4 with 75 mg/kg of tilmicosin in single injections. After three days, plasma, cardiac and hepatic malondialdehyde and reduced glutathione levels were measured with spectrophotometer. Red blood cell, white blood cell, platelet, haemoglobin, packed cell volume and percentage of leukocytes were also determined. At the end of the experiment, tilmicosin did not cause any statistically significant (P > 0.05) changes in haematological parameters such as red blood cells, white blood cells, platelet, haemoglobin, packed cell volume and percentage of leukocytes. Hepatic malondialdehyde and reduced glutathione levels increased (P < 0.05) only at the highest dose of tilmicosin. The results indicate that tilmicosin did not cause lipid peroxidation in the heart.
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    Melatonin prevents oxidant damage in various tissues of rats with hyperthyroidism
    (PERGAMON-ELSEVIER SCIENCE LTD, 2006) Mogulkoc, R; Baltaci, AK; Oztekin, E; Aydin, L; Sivrikaya, A
    Impairment of thyroid functions brings about pathological changes in different organs of body. Findings of in vivo and in vitro studies indicate that thyroid hormones have a considerable impact on oxidative stress. Melatonin reduces oxidative damage through its free radical eliminating and direct anti-oxidant effects. The present study was undertaken to determine how a 3-week period of intraperitoneal melatonin administration affected oxidative damage caused in experimental hyperthyroidism in rat. The experimental animals were divided into 3 groups (control, hyperthyroidism, hyperthyroidism+melatonin). Malondialdehyde (MDA) and glutathione (GSH) levels were determined in different tissues. MDA levels in cerebral, liver and cardiac tissues in hyperthyroidism group were significantly higher than those in control and hyperthyroidism+melatonin supplemented groups (p < 0.001). The highest GSH levels were observed in the group that was administered melatonin in addition to having hyperthyroidism (p < 0.001). These results show that hyperthyroidism increased oxidative damage in cerebral, hepatic and cardiac tissues of rat. Melatonin supplementation may also suppress oxidative damage. (c) 2006 Elsevier Inc. All rights reserved.
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    Pinealectomy inhibits antioxidant system in rats with hyperthyroidism
    (MAGHIRA & MAAS PUBLICATIONS, 2005) Mogulkoc, R; Baltaci, AK; Aydin, L; Oztekin, E; Sivrikaya, A
    OBJECTIVE: Thyroid hormones regulate energy metabolism and act on the mitochondria, which is an important source of free radicals in the cell. Reactive oxygen types play a significant role in physiological mechanisms, but in excessive amounts they can cause oxidative damage in molecules. The aim of the present study was to determine levels of lipid peroxidation caused by induced hyperthyroidism in cerebral, hepatic and cardiac tissues of pinealectomized rats. METHODS: Experimental animals used in the study were allocated to three groups as general control group, hyperthyroidism-sham pinealectomy group and hyperthyroidism-pinealectomy group. GSH and MDA levels in cerebral, hepatic and cardiac tissues were evaluated at the end of the 3-week study period. RESULTS: It was found that MDA levels in cerebral, hepatic and cardiac tissues were the highest in hyperthyroidism and pinealectomy group and that these values were higher in hyperthyroidism-sham pinealectomy group than in the control group (p < 0.001). it was seen that tissue GSH levels significantly increased in hyperthyroidism-sham pinealectomy group (p < 0.001) and that the increase in hyperthyroidism and pinealectomy group was higher than the increase in the control group only (p < 0.001). CONCLUSION: Results of our study show that MDA and GSH levels in cerebral, hepatic and cardiac tissues increased due to hyperthyroidism and that the increase in MDA levels became more evident and GSH levels were significantly suppressed after pinealectomy.
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    Short-term thyroxine administration leads to lipid peroxidation in renal and testicular tissues of rats with hypothyroidism
    (AKADEMIAI KIADO, 2005) Mogulkoc, R; Baltaci, AK; Oztekin, E; Ozturk, A; Sivrikaya, A
    Thyroid dysfunction brings about pathological changes in different organs of the body. The aim of the present study was to examine how experimental hypothyroidism and additional short-term high-dose thyroxine administration (one-week) affected lipid peroxidation in renal and testicular tissues of rats. The study was carried out on 30 male Spraque-Dawley rats. The experimental animals were divided into 3 groups as control, hypothyroidism and hypothyroidism + thyroxine administration. Both malondialdehyde (MDA) and glutathione (GSH) levels were lower in renal and testicular tissues of the hypothyroidism group than the control and hypothyroidism + thyroxine administration groups and the levels in hypothyroidism + thyroxine administration group were higher than those in the control and hypothyroidism groups (p < 0.001). Results of the study demonstrate that hypothyroidism reduced oxidant stress in kidney and testis tissues, but short-term, high-dose thyroxine administration in addition to hypothyroidism increased oxidant stress in the same tissues of rats.