Efficacy of melatonin as protectant against oxidative stress and structural changes in liver tissue in pinealectomized rats

Abstract

Previous observations demonstrated that physiological levels of metatonin, the pineal secretory product, are important in protecting against oxidative stress-induced tissue damage. We investigated the effects of pinealectomy and administration of exogenous melatonin on liver tissue in rats. Pinealectomized (Px) and sham-operated (non-Px) rats were used. We evaluated structural changes, reduced glutathione (GSH) levels and matondialdehyde (MDA) levels. Rats were divided into three groups (10 rats in each group): control. (non-Px), Px+vehicle and Px+metatonin (4 mg/kg given daily intraperitoneally for 10 days). Liver GSH levels were significantly tower in Px rats than in the control group. Melatonin administration significantly increased GSH levels (p<0.05). Px caused a significant increase in MDA levels as compared with the control group and metatonin administration to Px rats significantly reduced MDA levels in the liver (p<0.05). Sinusoidal dilatation to a varying degree developed in all Px rats. Severity of mononuclear cell. infiltration and sinusoidal congestion were tower in Px+melatonin group than in the Px group. These findings suggest that a significant increase in oxidative and structural changes occur in rat livers after pinealectomy, which can be diminished by melatonin treatment. (C) 2004 Published by Elsevier GmbH.