Melatonin Improves Blood Biochemical Parameters and DNA Integrity in the Liver and Kidney of Hyperthyroid Male Rats
The present study was carried out to investigate and compare the effect of hyperthyroidism either alone or in combination with melatonin on some blood biochemical parameters and DNA integrity in liver and kidney of male rats. For this purpose 75 mature male rats weighing 120-140g were randomly divided into five groups (control, hyperthyroid, hyperthyroid plus 1, 5 or 10 mg/kg bwt of melatonin, respectively). Hyperthyroidism was experimentally induced by daily I/P injection of L-thyroxine (0.2 mg/kg body weight). The melatonin treated groups were injected with the same dose of L-thyroxine followed by I/P injection of melatonin (1, 5 or 10 mg/kg, respectively). The study was carried out for 21 days. The last blood and tissue samples were collected one day after the end of the last injection (on the 22nd day). The results revealed that hyperthyroidism significantly increased the levels of urea and the activities of GOT, GPT, ALP as well as the percentage of DNA fragmentation in the liver and kidney. At the same time hyperthyroidism induced a significant decrease in level of creatinine. Treatment with the 3 doses of melatonin completely ameliorated the hyperthyroidism- induced increase in GPT and ALP, while 5 and 10 mg could completely counteract the hyperthyroidism- induced increase in urea and only the 10 mg melatonin could ameliorate the hyperthyroidism-induced increase in GOT activity. It is concluded that melatonin can ameliorate the hyperthyroidism-induced disturbance in blood biochemical parameters and DNA fragmentation.