| Objective: To study the neuroprotective effect of N-acetylcysteine (NAC) on the spinal cord injury via investigating the effect of N-acetylcysteine on the expression of NF-κBp65, TNF-α, IL-1βand IL-6 in rats after acute spinal cord injury.Methods: 1.One hundred and eight adult Sprague-Dawley rats, were randomly divided into three groups: laminectomy only group (group A), ASCI group (groupB) and N-acetylcysteine treated group after ASCI (group C). Each group were further divided into 6 sub-groups at 6h, 12h, 1d, 3d, 7d, and 14d after acute spinal cord injury. 2.Group B and C received acute spinal cord injury using modified Allen's method. The rats of group C received intraperitoneal injection of NAC (150mg/kg) right after injury and the following 3 days, while the other two groups received same volume of saline. 6h, 12h, 1d, 3d, 7d, and 14d after ASCI, the movements of hind limbs of rats in each sub-group were observed and evaluated by BBB score before the spinal cords were taken out for further investigation. 3.The morphological changes of spinal cord of each group were observed by Haematine and Eosin staining. 4.The expression of NF-κBp65, TNF-α, IL-1βand IL-6 in different spinal cord areas of each group were detected by immunohistochemistry. 5.The expression of NF-κBp65 protein in different time points of each groups were detected by Western blot.Results: 1.BBB score: Compared to group A, the hind limb motor function of rats in group B and C was significantly impaired, especially group B. After NAC treatment, the BBB scores of group C were much higher than that of group B at a later time after injury, which has statistics significance (P<0.01). 2.HE staining observation: Under light microscope, inflammatory cell infiltration, schistose bleeding within the gray matter, central area fragmentation, axonal disruption and demyelination were very obvious at the early stage after spinal cord injury. At the later stage after injury, a series of changes occur, such as neural cells apoptosis, glial cells proliferation, formation of glial scar and cavity at injured site. The spinal cord of the group A had no sign of inflammatory. 3.Immunohistochemistry results:The expression of NF-κBp65 has little change in group A at six observation points. The expression of NF-κBp65 protein were markedly increased in group B and C at 6h after spinal cord injury, and reached the peak at 12h after injury, then began a slow decline at 1d, and still kept a high level at 3d after injury, then returned to normal at 7d after injury. The expression of NF-κBp65 in group B was significantly higher than that of group C at 6h, 12h, 1d, and 3d after SCI, which had statistically significance (p<0.05). The expression change of NF-κBp65 in group B and C have same tendency. Similarly, few TNF-α, IL-1βand IL-6 positive expression were found in group A. The expressions of TNF-α, IL-1βand IL-6 in group B and C were significantly increased at early stage of acute injury spinal cord, and reached the peak at 12h-1d after injury, then decreased slowly at 3d after injury. The expression of TNF-α,IL-1βand IL-6 were higher in group B than in group C at 6h, 12h, 1d, and 3d after SCI, which had statistically significance (p<0.05). 4.Western blot detection: The group A showed a small amount of NF-κBp65 protein expression. The expression tendency of NF-κBp65 in group B and C were consistent in both Western blot and immunohistochemistry detection. The expression of NF-κBp65 protein were increased at 6h after spinal cord injury, and reached the peak at 12h-1d, then decreased slowly and returned to normal at 7d after injury. The expression of NF-κBp65 in group B was much higher than in group C at 6h, 12h, 1d, and 3d after spinal cord injury with statistically significant difference (P<0.05).Conclusion: N-acetylcysteine can significantly suppress the activation of NF-κBp65 and down-regulate the expressions of pro-inflammatory factors such as TNF-α,IL-1βand IL-6 in rats after spinal cord injury, and reduce the secondary inflammatory reactions after spinal cord injury, and exert neuroprotective effects on damaged spinal cord.
|
PDF Full Text Request