眼镜蛇毒神经生长因子对成年猫坐骨神经损伤后的作用

Effects of a Nerve Growth Factor Isolated and Purified from the Venom of Naja naja atra on Injured Sciatic Nerve in the Adult Cat

目的 探讨从眼镜蛇毒分离纯化出的神经生长因子 (nerve growth factor,NGF)对成年猫坐骨神经损伤后的影响。方法 制成成年猫坐骨神经损伤模型 ,损伤局部注射蛇毒 NGF 2μg/ (kg· d) ,分别治疗 10 d和 30d,并与对照组 (损伤坐骨神经 ,不给药物 )比较。结果 术后 10 d,对照组术侧远端神经纤维数量比治疗组明显减少(P<0 .0 1) ,治疗组术侧足底刺激出现早 ,肢体活动恢复快。术后 30 d,治疗组术侧远端神经纤维大量再生 ,再生神经纤维数量已明显超过对照组和术后 10 d组水平 (P<0 .0 1) ,但结构紊乱 ,轴突和郎氏结消失。术侧肢体在连续注射 NGF 16 d左右出现足底刺激反应消失 ,肢体瘫痪等改变。结论 眼镜蛇毒 NGF在神经损伤早期应用能减轻神经纤维发生的溃变 ,促进受损神经的再生与功能恢复 ;而损伤局部长时间注射蛇毒 NGF则会导致神经纤维增生过度 。

Objective To investigate the therapeutic effects of a nerve growth factor (NGF) isolated and purified from the venom of Naja naja atra on injured sciatic nerves in adult cat. Methods Model of sciatic nerve crush lesion in 20 cats was made. After the operation, in the therapeutic group, NGF(2 μg/kg) was injected intramuscularly into the cat's leg once a day for 10 d (n=5) and for 30 d (n=5) respectively; in the control group, NGF was not injected and the cats were allowed to survive 10 d (n=5) and 30 d (n=5) respectively. Results Ten days after the operation, the number of distal nerve fibers was significantly smaller in the control group than in the therapeutic group (P<0.01); the reaction to planta stimulation appeared earlier and the leg action recovered faster in the therapeutic group. Thirty days after the operation, the number of distal nerve fibers in the therapeutic group was significantly greater than that of other groups (P<0.01), but the histologic structure of the nerve fibers was in disorder and the axon and Ranvier node disappeared. About 16 days after injury and injection of NGF for consecutive days, the reaction to planta stimulation disappeared and leg paraplegia occurred in the operated side. Conclusion The results showed that NGF could obviously reduce the degeneration of nerve fibers and enhance the peripheral nerve regeneration and functional recovery from ingury early, but daily injection of NGF in the injured region for a long period could significantly result in over-regeneration of nerve fibers, and the conductive function of the injured peripheral nerves would be lost.