鞘内注射米贝地尔对神经痛大鼠脊髓nNOS表达的影响

Effects of mibefradil administered intrathecally on the expression of nNOS in spinal cord of the rats following chronic compression of dorsal root ganglion

目的:探讨脊髓T型钙通道在背根节慢性压迫(CCD)痛中的作用以及其对脊髓背角神经元神经型一氧化氮合酶(nNOS)表达的影响。方法:行为学部分,SD大鼠48只,随机分为6组,每组8只,即sham组、CCD组、CCD+生理盐水组;CCD+米贝地尔50μg组;CCD+米贝地尔100μg组;CCD+米贝地尔200μg组,sham组和CCD组在术前、术后1、3、5、7、14、21d分别测定大鼠机械和热痛敏,其余各组在手术后5d分别鞘内注射盐水、米贝地尔各个剂量,分别在术前、给药前、给药后30min、60min、120min、240min、480min分别测定大鼠机械和热痛敏。免疫组化部分,设正常对照组(normal),其余分组同行为学部分,每组6只。Normal、sham组和CCD组大鼠术后5d处死,其余各组动物在术后第5d鞘内单次给药后2h处死,取脊髓腰膨大做免疫组织化学实验。结果:CCD大鼠在手术后形成稳定的痛敏,鞘内单次注射米贝地尔各个剂量能抑制大鼠痛敏,并持续到给药后240min。CCD大鼠术后5d脊髓背角浅层nNOS阳性神经元明显增多,鞘内注射米贝地尔能抑制神经元nNOS的表达。结论:脊髓T型钙通道参与CCD大鼠机械和热痛敏的形成,且可能与脊髓背角神经元nNOS的表达有关。

AIM： To investigate the effect of mibefradil administered intrathecally on the pain threshold and the expression of neuron nitric oxide synthase （nNOS） in the spinal cord of the rats following chronic compression of dorsal root ganglion. METHODS ： The chronic compression of dorsal root ganglion （ CCD ） model was adopted. Three different doses of mibefradil, a T - type calcium channel blocker, were administered singly intrathecally to the rats after CCD 5 days. The mechanical withdrawal threshold （MWT） and thermal withdrawal latency （TWL） were determined with yon Frey hair and thermal radiation apparatus before mibefradil administered and after mibefradil administered 30 min, 60 min, 120 min, 240 min, and 480 min. Changes of nNOS expression in neurons of the spinal dorsal horn were detected by immunohistochemistry method, and the number of the nNOS positive neurons was counted under microscope. RESULTS： MWT and TWL declined significantly from the first day to the 21st day after CCD. Mibefradil administered intrathecally attenuated significantly both mechanical and thermal hyperagesia of the rats, and markedly inhibited the increase in the nNOS expression. CONCLUSION： These data show that T type calcium channel plays a key role in the CCD - induced mechanical and thermal hyperalgesia and possibly involves in the nNOS expression in the spinal.