The impact of melatonin on inflammatory response after acute spinal cord injury

Objective To explore the effects of melatonin (MT) on the expression of interleukin (IL)-10,interleukin-6 and interleukin-8 as well as the inflammatory reaction and nerve repair after acute spinal cord injury (SCI).Methods One hundred and eight Sprague-Dawley rats were randomly divided into a spinal cord injury group (group A),an MT treatment group (group B) and a sham operation group (group C),each with 36 rats.SCI models were established in the rats of groups A and B using a version of Allen's weight drop method (50gcf at the T12 level).Group C had removal of the lamina only.Ten minutes later,group A was injected with 5％ ethanol in saline (the MT solvent) and group B with 100 mg/kg of melatonin preparation.At 6,12,18 and 24 hours,IL-6,IL-8 and IL-10 levels in serum were detected in 6 rats of each group.At 18 hours post-surgery,spinal cord specimens were taken from 6 rats of each group for hematoxylin eosin staining,morphological examination and immunohistochemical SP detection of IL-10 expression.Results The specimens of group A showed inflammatory reaction and ulceration at 48 h; groups B and C had no ulcers.Group B showed the highest levels of IL-10 in serum and IL-10 mRNA in the spinal cord,while group C showed the lowest level.The differences were statistically significant.Group A had the highest levels of IL-6 and IL-8 and group C had the lowest.The difference between group B and groups A and C was significant.The morpho-logical observation showed that after melatonin treatment the IL-10 levels in the spinal cord's central canal and around the gray matter improved.Conclusions Melatonin can improve nerve lipid peroxidation and inflammatory reaction in the treatment of spinal cord injury by increasing IL-10 expression and inhibiting IL-6 and IL-8 expression. Key words: Spinal cord injury ;  Melatonin ;  Interleukin