Abstract: ObjectiveTo investigate the expression of pro inflammatory cytokine mRNA including interleukin 1β (IL-1β), interleukin 6 (IL-6) and tumor necrosis factor-α(TNF-α) after spinal cord injury (SCI), and the effect of methylprednisolone (MP) on the expression of the cytokine and neurological outcome after SCI in rats.MethodsA moderate SCI model was made with SD rats according to modified Allen's method. 56 SD rats were divided randomly into the sham group (n=4), SCI group (n=24), saline group (n=14) and MP group (n=14, MP 30 mg/kg injected throuh tail vein 30 min after injury). Samples of injured spinal cord were taken at 1 h, 4 h, 12 h, 24 h, 72 h and 7 day after SCI. The mRNA expressions of IL-1β,IL-6 and TNF-α in the spinal cord of rats were measured by semi-quantitative RT-PCR at 1 h, 4 h, 12 h, 24 h, 72 h and 7 d post-injury, and 4 h post-operation in the control group. The effect of MP (30 mg/kg, iv, within 30 minutes post-injury) on the expression of cytokine at 4 h post-injury was tested with RT-PCR. The neurological outcome of rats was evaluated with BBB scores.ResultsThe expression of the cytokine mRNA was little in the sham group and significantly increased in injured groups with IL-1β at 12 h, TNF-αat 4 h reaching peak after injury,and higher than that in sham group until 72 h (P<0.05). While, the expressions of IL-1β and TNF -α mRNA were inhibited obviously in MP group at 4 h after injury, but MP had no effect on the neurological outcomes.ConclusionMP can inhibit inflammatory reaction obviously.

Key words: spinal cord injury (SCI), cytokine, methylprednisolone (MP), inflammation