小剂量纳洛酮协同麻黄碱对脑缺血大鼠神经可塑性的影响

Effect of low doses of naloxone combined with ephedrine on neural plasticity after cerebral ischemia in rats

目的研究小剂量纳洛酮协同麻黄碱对动物运动功能恢复的影响,并通过对缺血周围区皮质GAP-43、SYP的检测,进一步探讨麻黄碱加速运动功能恢复的分子机制。方法雄性SD大鼠,采用Koizumi线栓法制备大鼠大脑中动脉闭塞(MCAO)模型,缺血2h后再灌注。分假手术组、自然恢复组、麻黄碱组、纳洛酮+麻黄碱组、纳洛酮组。术后分1、2、3、4周4个时间点,横木行走试验评定运动功能改善情况;免疫组化光密度定量法观察缺血周围区生长相关蛋白(GAP-43)、突触素(SYP)表达强度。结果横木行走试验显示麻黄碱组速度明显快于自然恢复组(P<0.05),而麻黄碱+纳洛酮组明显快于麻黄碱组(P<0.05);前3个时间点免疫组化光密度定量测定显示麻黄碱组GAP-43、SYP的表达水平明显高于自然恢复组(P<0.05),而麻黄碱+纳洛酮组明显高于麻黄碱组(P<0.05)。结论麻黄碱可促进大鼠脑缺血后的运动功能恢复,使GAP-43、SYP等蛋白表达增强。而小剂量纳洛酮协同麻黄碱进一步加速大鼠脑缺血后的运动功能恢复,使GAP-43、SYP表达显著增强,进一步证实提高脑内神经重塑的分子表达是麻黄碱促进神经康复的机制之一。

Objective To further investigate the effects of low doses of naloxone combined with ephedrine on motor recovery,and explore the molecular mechanism of low doses of naloxone combined with ephedrine in accelerating rehabilitation in rats. Methods Male SD rats were randomly divided into sham-operated group,natural recovery group ,ephedrine group ,naloxone combined with ephedrine group and naloxone group. The unilateral MCAO model was induced by using Koizumi＇s method. Beam walking test was performed to evaluate motor function improvement in 1,2,3 ,and 4 weeks after operation. Growth-associated protein43 （GAP-43）and synaptophysin （SYP） expression profile was observed immunohistochemically. Results Beam walking tests indicated that ephedrine group was faster than natural recovery group,while naloxone combined with ephedrine group was even faster than ephedrine group. Both GAP-43 and SYP significantly increased in immunoreaction product by optical density measurement in ephedrine group compared with natural recovery group, and they significantly increased in naloxone combined with ephedrine group compared with ephedrine group. Conclusions Naloxone combined with ephedrine may exert synergistic action,enhance the efficacy of ephedrine and further upregulate the expression of GAP-43 and SYP proteins.