The effects of melatonin against 2,3,7,8-tetrachlorodibenzo-p-dioxin induced oxidative damage in rat brain

The aim of this study was to investigate toxic effects of subacute TCDD (2,3,7,8-tetrachlorodibenzo-p-dioxin) applications and possible protection of melatonin against these effects on brain in rats.A total of 28 male Sprague-Dawley rats weighing between 230-250 g were used in present study. Rats were divided into four groups, each group including seven rats and the experimental period was 30 days. The control group was treated 0,5 ml corn oil by gavage and 0,5 ml liquid proportionally melatonin administration (9 parts physiological serum +1 part ethyl alcohol) intraperitoneally. 5 mg/kg dose of melatonin was applied intraperitoneally for Group 2 (Melatonin group), Group 3 (TCDD group) was given 500 ng/kg TCDD and Group 4 (co-administration TCDD and melatonin) was treated with TCDD (500 ng/kg) and melatonin (5 mg/kg) simultaneously. After 24 hours the last drug application rats were decapitated and their brain tissues were removed for biochemical analysis. The brain tissue malondialdehyde (MDA), reduced glutathione (GSH) levels and catalase (CAT) activities were measured spectrophotometrically.During the study period although there was determined significant increase starting weight with after experiments weight (p<0.05) in control, melatonin and TCDD groups, there was no changes in TCDD+Melatonin group. MDA levels increased in TCDD group (p<0.001) and melatonin treatment reduced this value. GSH levels decreased in TCDD group compared to control group and normalized in melatonin treated group simultaneously. Brain tissue CAT activities were not affected (p>0.05) in all groups.In conclusion, this study showed that TCDD caused increased MDA levels, decreased GSH levels by increased possible occurring free radical. However, well known antioxidant properties endogen melatonin may be amelioration in these parameters.Key words: Dioxin, Oxidative Stress, Antioxidant, Melatonin, Rat, Brain.