【作者】 宋昀；

【导师】 刘颖菊；

【作者基本信息】 重庆医科大学 ， 药理学， 2009， 硕士

【摘要】 目的:积雪草苷(Asiaticoside,AS)属中药积雪草的主要活性成分,本实验采用急性脊髓损伤大鼠模型,探讨AS对大鼠神经元损伤的保护作用,并初步探讨作用机制,为AS治疗ASCI提供理论依据。方法:大鼠随机分为模型组、甲基强的松龙(methylprednisolon,MP)组、AS高、低剂量(45mg/kg、15mg/kg)组及假手术组,用改良Allen’s打击法建立大鼠急性脊髓损伤模型。术后24h、72h、7d、14d和28d各时间点BBB评分法检测大鼠后肢运动功能,用苏木精-伊红染色对损伤脊髓组织进行病理检查,黄嘌呤氧化酶法检测大鼠损伤脊髓组织SOD活性改变,TBA法检测MDA含量变化,RT-PCR检测大鼠脊髓COX-2 mRNA表达,免疫组织化学法检测大鼠脊髓COX-2蛋白表达及原位末端标记法(TUNEL)检测大鼠脊髓神经元凋亡。结果:与假手术组相比,术后24h急性脊髓损伤模型组大鼠BBB评分明显降低,脊髓有广泛灶性出血,大量的红细胞渗出,间质性水肿严重,核固缩,脊髓MDA含量增加、SOD活性明显降低,脊髓神经元出现大量凋亡,COX-2 mRNA和蛋白表达明显增强;术后72h、7d、14d和28d以上指标逐步改善。与模型组相比,术后24h、72h、7d、14d和28d各时间点,AS高、低剂量治疗组(45mg/kg、15mg/kg)和MP组(30mg/kg)均能改善大鼠BBB评分,降低MDA含量,提高SOD活性,减轻大鼠脊髓神经元凋亡,下调脊髓COX-2蛋白及mRNA的表达(P﹤0.05)。结论:改良Allen’s打击法可致大鼠神经元损伤、后肢运动功能减退,诱导COX-2mRNA和蛋白表达。积雪草苷能减轻脊髓病理损伤,改善运动功能,对脊髓神经元有保护作用。其机制可能与抑制氧化应激和炎症反应,抑制神经元凋亡有关。更多还原

【Abstract】 Objective: To study the effects of Asiaticoside , the major active component of traditional Chinese herb‘Centella asiatica’, on model of acute spinal cord injury in rats and its possible protective mechanisms, and to provide a theoretical basis of AS for the treatment of ASCI.Methods : Rat model of acute spinal cord injury was established by modified Allen’s method. One hundred and forty rats were divided randomly into the normal group,the model group , and the groups treated with Asiaticoside (15mg/kg and 45mg/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 AS (45 and 15mg/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.Conclusion: Acute spinal cord injury can induce motoneuron damage in rats and decrease the rat hindlimbs locomotor function and induce markedly the expression of COX-2 mRNA and protein. The administration of Asiaticoside possesses neuroprotective effect on ASCI,which can improve neurological function recovery and attenuate secondary spinal cord injury.更多还原