Abstract: Objective To investigate the inhibitory effects of N- acetylcysteine (NAC) on inflammatory factors after acute spinal cord injury, and the mechanisms thereof. Methods A total of 54 clean and healthy adult female SD rats were divided into three groups according to the principle of randomization: simple laminectomy group (Sham group), spinal cord injury group (SCI group) and N-acetylcysteine group (NAC group), with 18 rats in each group. The Sham group was treated with T9- 10 laminectomy only without spinal cord injury. Aneurysm clamp was used to establish rat model of T9- 10 spinal cord injury in SCI group and NAC group. At the time of 15 min and 12 h after injury, the rats of NAC group were injected Nacetylcysteine intraperitoneally (150 mg/kg). At the time of 24 h post modeling, 12 rats were sacrificed in each group for observing the severity of tissue injury by using hematoxylin- eosin (HE) staining (6 rats), and detecting the contents of inflammation factors including tumor necrosis factor (TNF)- α and interleukin (IL)- 6 by using enzyme- linked immunosorbent assay (ELISA) (6 rats). The remaining 6 rats in each group were raised for 8 weeks. During the first week, the ones in NAC group were injected NAC twice a day at 12 h intervals for 7 d. Additionally, the neurological function evaluation was performed at week 1, week 2, week 4, week 6 and week 8 after injury in rats by using the spinal cord injury motor function score (BBB) and the inclined plate test. Results The results of HE staining showed that the spinal cord was intact without hemorrhage and inflammatory cell infiltration in Sham group. The morphology and inflammatory status were significantly worse in SCI group than those in NAC group and Sham group. The results of ELISA showed that the expressions of TNF-α and IL-6 were significantly higher in SCI group and NAC group than those in Sham group (P＜0.05), while the expression levels of TNF-α and IL-6 were significantly lower in NAC group than those of SCI group (P＜0.05). The BBB scores and inclined plate test showed that both were significantly lower in SCI group and NAC group than those of Sham group (P＜0.05), and the results were better in NAC group than those of SCI group. Conclusion NAC may promote the recovery of neurological function in rats by reducing the local inflammatory response through diminishing the contents of TNF-α and IL-6 in spinal cord.

Key words: acetylcysteine, spinal cord injuries, tumor necrosis factor-alpha, interleukin-6