RESUMO
Objective To investigate the effects of melatonin (MT) on rats with acute paraquat (PQ) poisoning. Method Fifty-four Sprague-Dawley (SD) rats were randomly divided into three groups (each group 18 rats) and given the following treatment: intragastric injection of PQ at 50 mg/kg (PQ); intragastric injection of paraquat followed by intraperitoneal injection of MT at 10mg/kg once a day (MT); intragastric injection of normal saline (Control). Serum assays for malondialdehyde (MDA) levels and superoxide dismutase (SOD) and glu tathione peroxidase (GSH-Px) activities were determined on the 1st, 3rd and 7th day post treatment. Clinical manifestations of poisoning and pathological changes in the lungs were also observed. Results Serum MDA levels were significantly increased (P ＜ 0.01), and SOD and GSH-Px activities significantly decreased (P ＜ 0.05) in the PQ group compared to the control group. Serum MDA levels were significantly decreased, and serum SOD and GSH-Px activities increased in MT group compared to the PQ group (P ＜ 0.05). Clinical manifestations of intoxication and pathological lung changes were also ameliorated in poisoned rats treated with MT. Condutions Administration of MT alleviates clinical manifestations of acute paraquat poisoning in rats by Limiting the damage from lipid peroxidation.