硬膜外不同浓度辣椒辣素对大鼠痛阈及脊神经根组织结构的影响

Effects of epidural capsaicin with different contrention on pain threshold and nerve tissue structure in rats

目的观察硬膜外不同浓度辣椒辣素(CAP)对大鼠痛阈及脊神经根组织结构的影响。方法选择成年雄性Wistar大鼠24只,体重250 g-300 g,随机分成4组:对照组、A、B、C组,每组6 只。用动尾试验测痛阈后,腹腔注射1%戊巴比妥钠40mg/kg麻醉,于L5,6间隙硬膜外穿刺置管。置管后A、B、C组分别注入0.1%、0.25%、0.5%CAP 0.4 ml,对照组注入10%Tween 80溶液(CAP赋形剂)0.4 ml。注药后3、7、14 d测痛阈,随后将L4-6背根神经取出。每组取5只在光镜下观察形态学变化,余1只在电镜下观察其超微结构变化。结果与对照组相比,注药后A、B、C组痛阈明显升高(P <0.05),B、C组引起神经组织水肿和各细胞器的损害较A组明显。结论硬膜外腔注入0.1%、0.25%、0.5%CAP可明显提高大鼠痛阈,但0.25%、0.5%CAP对脊神经根损害明显。

Objective To evaluate the effects of epidural capsaicin on pain threshold and nerve tissue structure in adult rats. Methods Twenty-four adult male Wistar rats weighing 250-300 g were used in this study.A catheter was inserted into epidural space at L5-6 according to the method of Philippe. 0.4 ml of capsaicin 0.1%（group A）, 0.25% （group B） or 0.5% （group C） or 10% Tween 80 （control group） was injected via the epidttral catheter. Pain threshold was measured by thermal stimulation of the tail before （baseline） and on the 3rd,7th and 14th day after epidural capsaicin. The animals were then killed. The lumbar segment （L4-6） of the spinal cord and spinal nerve roots were removed immediately for light and electron microscopic examination. Results Pain threshold was significantly higher in group A, B and C than in control group （ P 〈 0.05 ）. The degree of edema and damage to cell organelle were significantly greater in group B and C than in group A. Conclusion Epidural capsaicin can increase pain threshold but high doses of capsaicin are detrimental to spinal nerve.