辣椒素作用于眶下神经对初级传入神经影响的实验研究

Influence of capsaicin applied locally to infraorbital nerve on primary afferent nerve in adult rats, an experimental study

目的 探讨辣椒素局部给药于成年大鼠眶下神经干对初级传入神经的影响。方法 用 2 %辣椒素溶液直接给药于大鼠一侧眶下神经干 ,对侧做自身对照 ,分别在给药后 3d、1周、2周、3周、4周、5周、6周在电镜下观察双侧眶下神经纤维的变化 ,用免疫组化方法观测三叉神经脊束尾侧核区 (CNV)P物质 (SP)阳性颗粒的灰度值。结果 辣椒素给药后无髓神经纤维变性溶解 ,而有髓神经纤维完好 ;给辣椒素后CNV区SP免疫阳性颗粒灰度值明显高于对照侧 (P <0 .0 1) ,不同时间组之间SP含量差异无显著性。结论 辣椒素局部神经干给药能选择性毁损初级传入神经中的无髓纤维 ,减少CNV区SP含量。提示辣椒素局部给药对治疗三叉神经痛有临床意义。

Objective To observe the influence of capsaicin applied locally to infraorbital nerve on the primary afferent nerve in adult rats. Methods 2% capsaicin solution was directly applied to one lateral infraorbital nerve, and the contralateral nerve was taken as self control. Infraorbital nerves were observed under electronmicroscope 3,7,14,21,28,42 days after local administration in both experimental and control groups. Substance P(SP) like positive immunoreactive granules in both lateral nucleus caudalis spinalis nervi trigemini(CNV) were examined by immunohistochemical method. Results Degenerated unmyelinated fibers were found in capsaicin-treated nerves, while myelinated fibers remained intact. The grey scale value of. SP like positive immunoreactive granules in the experimental sides were markedly less than that in the control sides ( P <0.01), while no significant difference was present between the groups of varied durations. Conclusion Local administration of capsaicin can produce selective destruction of unmyelinated fibers in primary afferent nerves , and can reduce the levels of SP in regions of CNV . The results suggest that local administration of capsaicin has potential therapeutic value for trigeminal neuralgia.