Protective Effects And Mechanisms Of Madecassoside On The Acute Spinal Cord Injury In Rats

Objective:To investigate the protective effects of MC, the major active component of traditional Chinese herd'Centella asiatica', on the injury spinal neurons induced by the acute spinal cord injury in rats and further explore its possible protective mechanisms to make a primary exploration in the SCI therapy of MC.Methods :SD rat models by modified Allen's assay for the acute spinal cord injury were adopt. One hundred and forty-fourth rats were divided randomly into five groups: the normal group,the model group , and the groups treated with madecassoside((60mg/kg and 20mg/kg) and methylprednisolon(30mg/kg). At 24h, 72h, 7d, 14d and 28d after operation, motor functions of the rat hind limbs were determined by the BBB(Basso Beattie and Bresnahan), morphologic changes of spinal neurons were evaluated by HE staining, the changes of SOD activity and MDA contents in rat spinal cord were measured by xanthinoxidase method and the method of TBA separately. The COX-2 mRNA and COX-2 protein expression in rat spinal cord were detected by RT-PCR and immunohistochemistry, separately. The apoptosis of neural cells was assessed with the terminal deoxynucleotidyl transferase mediated deoxyuredine triphosphate—digoxin nick end labeling (TUNEL)method.Results: It was observed that at 24h, 72h, 7d, 14d and 28d after operation, the motor functions of the rat hind limbs about the acute spinal cord injury model group were decreased,extensive focal hemorrhage of spinal cord, large quantity of diapedesis of erythrocyte, severe interstitial edema and karyopyknosis were observed,levels of MDA were increased and activities of SOD were decreased in spinal cord tissue,TUNEL positive cells were significantly increased, as well as the protein and mRNA expression of COX-2 in the spinal cord increased,the extreme value of every index presented at 24h after operation; Treatments with MC (60 and 20mg/kg) or MP(30mg/kg)could significantly ameliorate the motor functions of the rat hind limbs, markedly decrease the elevation of MDA levels and increase the activities of SOD in spinal tissue. Meanwhile, TUNEL positive cells were significantly decreased , the damage to nerve cells were alleviated and protein and mRNA expression of COX-2 in spinal tissue induced by the acute spinal cord injury were inhibited,with statistical significance as compared with the model group at 24h, 72h, 7d, 14d and 28d after operation. MC effect has dose-depedent manner.Conclusion: The modified Allen's method finds the better way to simulate the dynamics process of acute spinal cord injury. MC has the protective effect on damage of neurons, and its mechanism may be related to enhance the body's ability of anti-oxidative, inhibit neuronal apoptosis, and reduce neurons's protein and mRNA expression of COX-2.