甲基强的松龙对大鼠损伤脊髓BDNF、NMDA受体表达及神经行为学的影响

目的研究甲基强的松龙(MP)对脊髓损伤大鼠神经行为学、脑源性神经营养因子(BDNF)和N-甲基-D-天冬氨酸(NMDA)受体表达的影响。方法建立脊髓损伤(SCI)大鼠模型,将大鼠随机分为假手术组、SCI组和MP治疗组,每组16只。MP治疗组在SCI术后8h内肌注50mg/kg MP,此后肌注量每天减少10mg/kg,1次/d,共5d。各组取8只大鼠在术后1d、7d、28d行后肢运动功能BBB评分,并于术后28d用免疫组织化学染色观察各组BDNF在脊髓的分布、阳性细胞定位及数量变化;术后13d用[3 H]MK-801放射性配基测定各组另8只大鼠脊髓中NMDA受体亲和力(Kd)和最大结合容量(Bmax)。结果 SCI后MP治疗组中BDNF阳性细胞数较SCI组增加(P<0.05),但亚细胞定位仍分布在细胞浆,且BBB评分亦较SCI组高;NMDA受体Kd高于SCI组,Bmax较SCI组低,差异均有统计学意义(P<0.05)。结论 MP能改善脊髓损伤大鼠后肢功能,增加BDNF含量和降低NMDA受体表达。

Effect of methylprednisolone on neurological behavior and the BDNF and NMDA receptor expression after traumatic spinal cord injury in rats

Objective To study the effect of methylprednisolone on spinal cord injury rats’ neural behavior and the expression of brain derived neurotrophic factor(BDNF) and N-methyl-D-aspartic acid(NMDA).Methods To establish rat model of spinal cord injury(SCI),the rats were randomly divided into sham operation group,SCI group and methylprednisolone group(n=16 in each group).Eight rats were used for the behavioral assessment and BDNF measurement,the other eight animals was for the NMDA receptor test in each group.Within 8 h spinal cord contusion,methylprednisolone(50 mg/kg) was injected for methylprednisolone group,then after that the intramuscular injection of methylprednisolone was per day reduction in 10 mg/kg,till 5 days.By using immunohistochemical staining,the distribution of BDNF in the spinal cord and positive cell localization was observed and the number of positive cells were counted.The NMDA receptor affinity(Kd) and maximum binding amount(Bmax) were measured with MK-801 radioligand method,and the rat hind limb functional was also evaluated with BBB score analysis.Results Both the number of BDNF positive cells and the BBB score in methylprednisolone group was significant higher than that of SCI group;While increased receptor affinity(Kd) and decreased Bmax for NMDA receptor in methylprednisolone group was seen less than in SCI group(P<0.05).Conclusion Methylprednisolone can improve the function of rat hind limb,increase BDNF level and decreased NMDA receptor expression after spinal cord injury.