Effects of melatonin on expression of TNF-α in rats with acute spinal cord injury

Aim:To investigate the effects of melatonin( MT) on the expression of tumor necrosis factor-α( TNF-α) in acute spinal cord injury( SCI) rats. Methods:A total of 108 SD rats were randomly allocated into three groups:Sham group only accepted laminectomy without SCI,and SCI group and SCI + MT group used the modified Allen's method to establish SCI model. 100 mg/kg MT was given to the rats in SCI + MT group,and 5% ethanol,to SCI group at 10 min after the model establishment. At 12 h,spinal cord samples of 6 rats from each group were prepared for histological examination using HE and immunohistochemical SP staining to detect the expression of TNF-α. At 1,12,24,48 and 72 h,6 rats in each group were executed,the serum level of TNF-α was determined by ELISA,and the expression of TNF-α mRNA was detected by RT-PCR. Results:Compared with SCI group,the pathological changes in SCI + MT group were significantly alleviated. Immunohistochemical staining showed that TNF-α protein in spinal cord tissue mainly located in the cytoplasm and nucleus of neurons and glial cells; SCI group was the highest,SCI + MT group followed,and Sham group was the lowest( F = 504. 239,P 0. 001). At different time points,the serum level of TNF-α and the expression of TNF-α in spinal cord tissue in SCI + MT group were significantly lower than those in SCI group,but still higher than those in Sham group( P 0. 05). Conclusion:MT may reduce secondary injury of SCI by inhibiting the expression of TNF-α.