The effects of acute melatonin and ethanol treatment on antioxidant enzyme activities in rat testes.

The pineal hormone melatonin (N -acetyl, 5-methoxytryptamine) was recently accepted to act as an antioxidant under both in vivo and in vitro conditions. In this study, we examined the possible preventive effect of melatonin on ethanol-induced lipid peroxidation in rat testes. Thirty-seven male Wistar albino rats, 5.5--6 months old, were randomly divided into four groups (9--10 animals in each). The first group (control animals) received 4% ethanol at similar intervals to the experimental groups to equalize the stress effect. The second group received only melatonin i.p. 7 mg kg(-1)bw three times over 1.5 h intervals. The third group received only 30% alcohol 3 g kg(-1)bw twice daily. The fourth group were treated with melatonin and ethanol according to the above protocol, melatonin injections preceding ethanol treatments. The product of lipid peroxidation, malondialdehyde (MDA) and antioxidant enzymes, superoxide dismutase (Cu--Zn SOD), glutathione peroxidase (GPx) and catalase (CAT) were measured in the post-mitochondrial fraction of the testes. MDA levels were significantly increased due to acute ethanol intoxication. GPx activity was higher in the three experimental groups than the control levels. The activity of CAT was increased significantly in the melatonin plus ethanol-treated group but the other groups appeared not to be influenced by acute ethanol treatment. Cu--Zn SOD activity remained unaltered. These results suggest that antioxidants may be a protective agent for the testicular injury caused by ethanol consumption.