鞘内注射左旋布比卡因下调甲醛炎性痛大鼠远位触液神经元P物质的表达

目的观察鞘内注射左旋布比卡因对甲醛炎性痛大鼠P物质(substanceP,SP)在脊髓背角及远位触液神经元(thedistal cerebrospinal fluid contacting neuron,dCSF-CN)表达的影响。方法采用CB-HRP大鼠侧脑室注射示踪标记dCSF-CN;48h后先鞘内注射0.5%左旋布比卡因10μl(并以鞘内注射10μl人工脑脊液作对照),大鼠左后掌足跖部皮下注射2.5%福尔马林建立炎性痛模型,记录大鼠舔足时间,1h后测定机械缩足阈值(mechanical withdrawal threshold,MWT)评估机械痛敏;免疫组织化学光镜镜检及免疫电镜镜检P物质在脊髓背角(L4~5)及dCSF-CN的表达。结果鞘内注射左旋布比卡因减少大鼠福尔马林试验的舔足时间(P<0.01),MWT值无变化(与基础值对比,P>0.05),SP在脊髓背角及dCSF-CN的表达弱于对照组(P<0.01)。结论鞘内注射左旋布比卡因减低脊髓伤害性疼痛反应及下调SP在dCSF-CN的表达。

Intrathecal levobupivacaine downregulates substance P expression in the distal cerebrospinal fluid contacting neuron for formalin-induced inflammatory pain in rats

Aim To investigate the effects of intrathecal levobupivacaine(LB)on substance P(SP)expression in spinal dorsal horn(L4~5)and the distal cerebrospinal fluid contacting neuron(dCSF-CN)in a rat model of formalin induced inflammatory pain.Methods Twelve male Sprague-Dawley rats(290~310 g,Grade SPF)were randomly divided into 2 groups with 6 in each.Rats were anesthetized with sodium pentobarbital(40 mg·kg-1,ip)and then fixed in the stereotaxic instrument.A 3 μl volume of 30% CB-HRP to trace dCSF-CN was injected into one of the rats'lateral ventricles.The animals kept alive,forty eight hours later artificial cerebrospinal fluid(ACSF)10 μl and 0.5% LB 10 μl(diluted with ACSF)were intrathecally injected in group ACSF and group LB respectively.Inflammatory pain was induced by formalin injection into left hind paw.Then nociception of the animals was assessed behaviorally with the formalin test.Two hours after formalin administration,rats were sacrificed with deeply anesthesia and transcardially perfused.L4~5 segments of spinal cord were removed for immunohistochemical SP-labeling.Brainstem segments containing dCSF-CN were removed for SP/CB-HRP dual-labeling with immunohistochemical procedures and colloidal gold immunoelectronmicroscopy.Results LB significantly reduced paw licking time in the formalin test(P<0.01vsgroup ACSF).The mechanical withdrawal threshold of the rats kept unchanged in group LB(P> 0.05vsbaseline,P<0.01vsgroup ACSF).SP-expres-sions in spinal dorsal horn(L4 ~5)and dCSF-CN were down-regulated by intrathecal LB(P<0.01vsgroup ACSF).Conclusion It is revealed that intrathecal levobupivacaine attenuates spinal nociception and downregulates substance P-expression in dCSF-CN more significantly following formalin-induced inflamma-tory pain in rats.