Expression of tumor necrosis factor alpha and its mRNA in the spinal cord following a weight-drop injury.

The effect of traumatic spinal cord injury (SCI) on the expression of tumor necrosis factor (TNFalpha) and its mRNA was examined. Quantitative reverse transcription polymerase chain reaction assay showed TNFalpha mRNA level increased > 20-fold at the lesion site by 1 h after the injury compared to that in uninjured controls. The TNFalpha mRNA level was still significantly higher than in the controls 72 h after the injury. TNFalpha mRNA in the samples collected immediately caudal to the lesion site was also increased. Levels of TNFalpha protein, determined by a cytotoxic bioassay, were also significantly increased at the lesion site. The TNFalpha protein level was maximal 1 and 8 h after the injury and still significantly higher than in the controls 24 h post-injury. The present results demonstrate that TNFalpha is rapidly induced in the spinal cord after the injury, and it may play a significant role in secondary events in SCI.