Melatonin protection on mercury-exerted brain toxicity in the rat.

The effect of melatonin on the neurotoxicity induced by mercuric chloride was studied. Adult rats were fed orally with two different doses of mercuric chloride (2 mg; 4 mg/kg body weight) to evaluate brain toxicity with respect to cerebral hemisphere, cerebellum, and medulla oblongata regions for 60 days with or without supplementation with melatonin (5 mg/kg body weight) intraperitoneally. The results suggest that the graded doses of mercury elicit the depletion of enzymatic activities, such as adenosine triphosphatase, succinate dehydrogenase, phosphorylase, alkaline phosphatase, acid phosphatase, altered glycogen, total protein, and lipid peroxidation levels in the cerebral hemisphere, cerebellum, and medulla oblongata of the brain, thereby affecting their respective functions. Blood glucose and mercury levels increased, followed by a reduction in body and organ weights. All these effects seemed to be severe in the cerebral hemisphere of the brain. Further affected indices were, to some extent, maintained in the brain of animals cotreated with melatonin, showing its protective role against mercury-exerted neurotoxicity.