Effect of melatonin on cerebral edema in rats

OBJECTIVE: Melatonin (5-methoxy-N-acetyltrypamine), a chemical naturally pr oduced in the pineal gland, has been suggested to be a free radical scaveng er and an antioxidant. In the present study, the effect of melatonin on col d-induced brain edema was evaluated by determination of cerebral water cont ent, blood-brain barrier permeability, and areas of infarct; the effects we re also studied histopathologically. METHODS: Brain edema was produced in rats by creating a lesion via cortical freezing. Animals were separated into four groups: sham-operated (craniect omy only); control (cold injury); sham-vehicle (cold injury plus saline); a nd melatonin treatment (cold injury plus melatonin). Melatonin was administ ered (50 mg/kg intraperitoneally) 15 minutes after the cold injury was indu ced. Twenty-four hours later, tissue samples from the core, from the periph ery of the cold-injured hemisphere, and from the contralateral hemisphere s ymmetrical to the cold injury were obtained. RESULTS: Melatonin treatment reduced edema (mean +/- standard deviation; 86 .22 +/- 1.54% in the control group versus 80.78 +/- 2.76% in the melatonin treatment group, P < 0.001) and blood-brain barrier permeability (45.34 +/- 2.75% in the control group versus 38.26 +/- 3.40% in the melatonin treatme nt group, P < 0.001) at the periphery of cold injury. Area of infarct reduc ed from 5.84 +/- 0.58% in the control group to 3.30 +/- 0.89% in the melato nin treatment group (P < 0.001). The effect of melatonin was also confirmed histopathologically. CONCLUSION: Melatonin was found to be neuroprotective in instances of cold- induced brain edema. Thus, melatonin may be a valuable therapeutic agent in the treatment of cerebral edema.