硬膜外不同时期麦帕克林治疗对实验性神经根性疼痛的影响

目的 探讨不同时期硬膜外应用选择性磷脂酶A2 (PLA2)抑制剂麦帕克林(mepacrine)治疗对大鼠后足底机械刺激疼痛阈值的影响.方法 取大鼠自体尾部椎间盘组织放置在L5神经根下,造成对L5神经根的直接压迫,建立椎间盘突出致神经根性疼痛动物模型.硬膜外置管,采用早期预防性给药及晚期治疗性给药方法,观察麦帕克林对大鼠后足底机械刺激疼痛阈值的影响;同时设立空白对照组及磷酸盐缓冲液组(PBS)作为对照研究.结果 与对照组和PBS组相比,早期预防性硬膜外给予麦帕克林完全抑制了大鼠1周内双侧后足底机械刺激疼痛阈值的降低,而当术后3周机械刺激阈值降到最低时治疗性硬膜外给予麦帕克林对疼痛没有明显的改变.结论 在椎间盘突出的早期阶段,PLA2在椎间盘源性神经根性疼痛中起着重要作用,硬膜外应用PLA2抑制剂麦帕克林可以有效地减缓早期疼痛的产生;当椎间盘突出到一定阶段,压迫因素成为致痛的主因,这时硬膜外再给予麦帕克林对疼痛无明显缓解.

The effect of epidural mepacrine therapy at different periods on experimental pain of nerve root

Objective To explore the effect of epidural mepacrine which is the selective inhibitor of phospholipase A2 （PLA2） therapy applied at different periods on paw withdraw mechanical threshold （PWMT） of the hind pelma of the rat. Methods The autologous structure of coccygeal intervertebral discs in the rat was taken and placed under L5 nerve root. Direct neurothlipsis of L5 nerve root was produced. The animal model of the nerve root pain induced by herniated disk was established. The epidural tube was placed. The early prophylactic and late remedial method of drug administration was adopted to observe the effect of mepacrine on paw withdraw mechanical threshold （PWMT） of the hind pelma of the rat. Meanwhile, a blank control group and a phosphate buffer saline （PBS） group were set up for comparison. Results Compared with the control group and the PBS group, early prophylactic therapy of epidural mepacrine completely suppressed the decrease of PWMT of both hind pelmas of the rat in 1 week. But when the PWMT decreased to the lowest point in 3 weeks after the surgery, remedial epidural mepacrine therapy had no obvious effect on the pain. Conclusions PLA2 plays an important role in discogenic nerve root pain in the early stage of protrusion of intervertebral disc. The epidural mepacrine, inhibitor of phospholipase A2 （PLA2）, applied in the early stage can effectively relieve the pain. When intervertebral disc protrudes to a degree that compression becomes the main course which produces pain, epidural mepacrine therapy has no obvious effect on the pain.