Effects of pinealectomy and exogenous melatonin on the brains, testes, duodena and stomachs of rats

BACKGROUND, It is generally agreed that physiological levels of melatonin, a hormone secreted by the pineal gland, are im - portant in protecting against oxidative stress-in - duced tissue damage. AIM, We investigated the effects that pinealec - tomy and the administration of exogenous mela - tonin have on the brains, testes, duodena and stomachs of rats. MATERIALS AND METHODS, Pinealec - tomized (Px) and sham-operated (non-Px) rats were used.We evaluated structural changes, and catalase (CAT), reduced glutathione (GSH), su - per oxide dismutase (SOD) and malondialdehyde (MDA) levels. The rats were divided into the fol - lowing five groups (eight rats in each group): sham (non-Px), Px+ vehicle, Px+ melatonin (10 mg/kg given daily intraperitoneally for a week), melatonin and ethyl alcohol. RESULTS, The antioxidant levels in the tissue of Px rats were significantly lower than in those of the sham group. Administering melatonin sig - nificantly increased antioxidant levels ( p < 0.05). The Px rats also showed a significant increase in MDA levels when compared to the sham group, and administering melatonin to the Px rats significantly reduced their MDA levels ( p < 0.05). The severity of caspase-3 staining was lower in the Px+ melatonin group than in the Px+vehicle group. CONCLUSIONS, These findings suggest that significantly more oxidative and structural changes occur in rats' brains, spinal cords and testes after pinealectomy, but that this can be di - minished by melatonin treatment. However, Px does not have important effects on the duode - num and stomach.