透明质酸酶对慢性压迫性神经损伤模型中神经源性疼痛的作用研究

Effect of Hyaluronidase on Neuropathic Pain in Chronic Constriction Nerve Injury Rats

目的:研究透明质酸酶对坐骨神经的疏松结扎(CCI)模型神经源性疼痛的作用,初步探讨临床通过相关穴位点注射透明质酸酶治疗慢性疼痛的机制。方法:采用CCI模型,记录损伤神经异位自发放电和热痛刺激的敏感程度。结果:用透明质酸酶作用于术后7d大鼠的损伤处并进行坐骨神经自发放电的测量,发现在测量的12只模型中,有8只模型的自发放电得到了有效的抑制,这8只的平均抑制率为50.9%±12.4%。在热刺激行为学实验中,损伤局部持续注射透明质酸酶溶液的CCI大鼠在术后3d、6d和14d的热刺激敏感度明显低于局部注射生理盐水的对照组CCI大鼠。通过CCI大鼠损伤坐骨神经组织切片观察,发现神经纤维排列混乱,纤维间存在空泡状间隙,并且在间隙周围分布着染成深色的多糖链;而经过透明质酸酶作用后CCI损伤坐骨神经切片观察,空泡状空隙与深色多糖链沉淀消失,神经排布较处理前更加规则。结论:细胞外基质与神经生理功能密切相关,透明质酸酶能够有效降低CCI模型的异位自发放电;临床穴位注射透明质酸酶改变穴位点聚集的细胞外基质,从而起到镇痛作用。

Objective: To observe the effect of hyaluronidase on neuropathic pain in chronic constriction nerve injury (CCI) rats and analyze the possible mechanisms of acupoint-injection of hyaluronidase (a typical enzyme for decomposing extra-cellular matrical polysaccharide) for analgesia. Methods: A total of adult SD rats were randomly divided into control group (n=10) and treatment group (n=12). CCI pain model was established by ligating the left sciatic nerve loosely with gauge-4 chromic catgut. Silver chloride electrode was used to record the ectopic spontaneous discharges of the proximal filaments of the injured nerve 2 cm above the ligated site and the latency of foot withdrawal reaction to heat stimulation was detected with hot-plate test. After CCI, the injured sciatic nerve was taken out and cut into sections which were stained with periodic acid Schiff (PAS)-hematoxylin and eosin (HE) techniques. Results: In our experiments, the rate of ectopic spontaneous discharges of the nerve filament was significantly reduced by 50.9%±12.4% in 8 of the 12 CCI rats after applying hyaluronidase to the injured site but was not affected by application of normal saline or mechanical stimulation, suggesting an injured nerve discharge. Behavioral test for neuropathic pain indicated that heat hyperalgesia of CCI rats could be reduced by applying hyaluronidase to the CCI site. After CCI, the pain reaction (foot withdrawal) latency was delayed significantly. The difference values of the latency of foot withdrawal reaction between post- and pre-CCI on the 3 rd , 6 th and 14 th day in experimental group were lower or significantly lower (14 th day, P<0.05) than those of control group, indicating that local application of hyaluronidase could prevent the development of heat hyperalgesia. Histological observation displayed disordered arrangement of nerve fibers with bigger irregular spaces among them,swelling of tissues, deposition of polysaccharide granules and abundant cellular neuclei among the fibers, indicating appearance of inflammation in the injured portion of the sciatic nerve. In hyaluronidase treated samples, no deposition of protein polysaccharide granules was found, the arrangement of nerve fibers and cellular nuclei were basically normal. Conclusion: Extra-cellular matrix has a close relation with neuro-physiological functions and hyaluronidase can effectively suppress CCI induced ectopic spontaneous discharges. It suggests that clinical application of acupoint-injection of hyaluronidase to change local extra-cellular matrix may have an analgesic effect on chronic pain.