Both zinc deficiency and supplementation affect plasma melatonin levels in rats

At physiological levels, zinc and various hormones affect each other reciprocally. Reduction in zinc levels in pinealectomized rats suggests the relation between zinc and melatonin. The effect of both zinc deficiency and supplementation on plasma melatonin levels in rats were investigated in this study. The study was done in Selçuk University, Experimental Medicine Research and Application Center. Twenty-four adult male Sprague Dawley rats were divided into 3 groups. Eight rats were fed with zinc-deficient diet. Zinc supplementation was administered intraperitoneally to 8 rats. The remaining 8 rats were used as controls. All rats sacrificed 3 weeks later. Plasma melatonin and zinc levels were determined.  The plasma zinc levels of the zinc-supplemented group were higher than those of the other groups as expected (P<0.01). Similarly, the melatonin levels in the zinc-supplemented group were higher than those in the other groups. A significant decrease was observed in melatonin levels of the zinc-deficient group compared to the control and zinc-supplemented group (P<0.01). The results of this study suggest that zinc deficiency decreases the melatonin levels and zinc supplementation may increase the plasma melatonin levels in rats

The effect of estradiol and progesterone application on leptin concentration in ovariectomized rats

The aim of the present study was to investigate the effects of estradiol and progesterone application on leptin secretion in ovariectomised rats.  The study included 30 adult female Sprague-Dawley rats. Rats were divided into three groups as follows:Group 1; Sham ovariectomy group (n=10), Group 2; Ovariectomy group (n=10), Group 3; Ovariectomized and estradiol propionate (450 μg/kg rat) and medroxyprogesterone acetate (15 mg/kg rat) supplemented group (n=10). One week after ovariectomy, rats in Group 3 were injected estradiol and progesterone for 4 weeks. Twenty-four hours after the last injection, rats were decapitated and blood samples were collected for leptin analysis. Serum leptin levels in Group 2 were found significantly higher than those in Groups 1 and 3 (p<0.01), while those in Group 3 were significantly lower when compared to Group 1 (p<0.01). The findings of the present study have shown that ovariectomy led to a significant increase in leptin levels. However, administration of estradiol and progesterone in combination following ovariectomy inhibites increases of leptin levels

The effect of thyroxine administration on lipid peroxidation in different tissues of rats with hypothyroidism

Thyroid dysfunctions bring about pathological changes in different organs of the body. Findings obtained from in vivo and in vitro studies point out that thyroid hormones have a strong impact on oxidative stress. The present study was conducted to demonstrate how high-dose thyroxin administration for one week affected oxidative damage formed in experimental hypothyroidism. The study was carried out with 30 Spraque-Dawley species male rats. The experimental animals were divided into 3 groups (Group 1, control; Group 2, hypothyroidism; Group 3, hypothyroidism + thyroxine administration). Malondialdehyde (MDA) and glutathione (GSH) levels were determined in cerebral, hepatic and cardiac tissues after the experimental period. MDA and GSH levels in cerebral, hepatic and cardiac tissues of hypothyroidism + thyroxine supplemented group were higher than those in the control and hypothyroidism groups (p<0.001). The same parameters were higher in the control group than those in the hypothyroidism group (p<0.001).  The results of the present study show that hypothyroidism reduced the oxidative damage in cerebral, hepatic and cardiac tissues of rats. However, high-dose thyroxine administration in addition to induced hypothyroidism increased oxidative damage in the same tissues and that this damage could not be prevented despite the increase in the antioxidant system activity

Selenium prevents lipid peroxidation in liver and lung tissues of rats in acute swimming exercise

PubMed ID: 25773950Background: Selenium, which is critical for human health, is necessary for various metabolic processes, including thyroid hormone metabolism, protection against oxidative stress, and immune function. Objective: The present study aims to examine how selenium administration affects lipid peroxidation in liver and lung tissues of rats subjected to acute swimming exercise. Methods: The study included 32 Spraque-Dawley adult male rats divided into Group 1 (general control), Group 2 (selenium-administered), Group 3 (swimming), and Group 4 (selenium-administered swimming). MDA and GSH levels were determined in liver and lung tissues. Results: The highest MDA values in the liver and lung tissues were found in group 3 in the study. MDA value in group 4 was higher than those in groups 1 and 2. Group 4 had the highest liver and lung GSH levels. GSH levels in Group 3 were higher than those in groups 1 and 2. Conclusion: Results of the study indicate that acute swimming exercise causes lipid peroxidation in liver and lung tissues, while selenium administration prevents free radical formation by increasing antioxidant activity (Tab. 2, Ref. 26). Text in PDF www.elis.sk