BACKGROUNDThe iron catalyzed lipid peroxidation plays an important role in the autodestruction of the injured spinal cord. This study was to detect the antioxidation of melatonin against spinal cord injury (SCI) in rats.

METHODSSity Sprague-Dawley rats were randomly divided into four groups: group A (n = 15) for laminectomyanly, group B (n = 15) for laminectomy with SCI, group C (n = 15) for SCI and intraperitoneal injection of a bolus of 100 mg/kg melatonin, and group D (n = 15) for SCI and intraperitoneal injection of saline containing 5% ethanol. The SCI of animal model was made using modified Allen's method on T12. Six rats of each group were sacrificed 4 hours after injury, and the levels of free iron and malondialdehyde (MDA) of the involved spinal cord segments were measured by the bleomycin assay and thiobarbituric acid (TBA) separately. Functional recovery of the spinal cord was assessed by Modified Tarlov's scale and the inclined plane method at 1, 3, 7, 14, 21 days after SCI. The histologic changes of the damaged spinal cord were also examined at 7 days after SCI.

RESULTSAfter SCI, the levels of free iron and MDA were increased significantly and the modified Tarlov's score and inclined plane angle decreased significantly in groups B and D. In group C, the Tarlov's score and inclined plane angle were increased significantly at 7, 14 and 21 days, with histological improvement.

CONCLUSIONMelatonin can reduce the level of lipid peroxidation and prevent damage to the spinal cord of rat.