喷他佐辛介导的sigma-1受体在大鼠神经病理性疼痛模型中的作用及机制研究

摘要

目的 探讨喷他佐辛(PTZ)介导的sigma-1受体(Sig-1R)在大鼠神经病理性疼痛模型中的作用及机制.方法 健康成年无特定病原体(SPF)级雄性SD大鼠48只,6～8周,体重230～250 g,由广东省医学实验动物中心提供.采用随机数字表法分为对照组(CON组)、模型组(MOD组)、PTZ处理组(PTZ组)和PTZ+Sig-1R拮抗剂(BD1047)处理组(PTZ+BD组)每组12只.MOD、PTZ和PTZ+BD组大鼠建立保留性神经损伤的神经病理性疼痛模型,CON组大鼠不做任何处理.模型制备完成后,PTZ单次用量为2 mg/kg,PTZ+BD组大鼠实验前2d静脉注射BD1047 2 mg·kg-1·d-1,以生理盐水为对照.于术前1d,治疗后2、24和48 h时测定机械缩足反射阈值(MWT)和热痛,最后一次检测痛阈值后麻醉处死各组大鼠,提取L4-6节段脊髓,采用Western blot和RT-qPCR法测定术侧L4-6节段脊髓Sig-1R、丝氨酸消旋酶(Srr)、磷酸化细胞外信号调节激酶1/2(p-ERK1/2)的表达.结果 与CON组比较,MOD组大鼠治疗后疼痛明显增加.PTZ组大鼠治疗后2、24和48 h时50％缩爪阈值和热痛差异性评分降低而缩腿时间增高.PTZ+BD组50％缩爪阈值和热痛差异性评分较MOD组增高,但低于PTZ组;缩腿时间较MOD组降低,而较PTZ组增高.与CON组比较,MOD、PTZ和PTZ+BD组Sig-1R、Srr和p-ERK 1/2表达均显著上调.与MOD组比较,PTZ组Sig-1R和Srr表达显著上调,但p-ERK 1/2表达下降;PTZ+BD组Sig-1R和p-ERK1/2表达下调,但Srr表达差异无统计学意义.PTZ+BD组Sig-1R和Srr表达较PTZ组均显著下调,但p-ERK1/2表达差异无统计学意义.结论 PTZ可改善大鼠神经病理性疼痛,其机制可能与Sig-1R和Srr上调、p-ERK 1/2下调有关.%Objective To explore the role and mechanism of pentazocine (PTZ)-mediated sigma-1 receptor (Sig-1R) in rats with neuropathic pain.Methods Forty-eight male healthy sprague-dawley rats of specific pathogen free,weighing 230-250 g,aged 6-8 weeks,from Guangdong Medical Laboratory Animal Center,were randomly divided into four groups:control group (CON),model group (MOD),PTZ group (PTZ) and PTZ and Sig-1R antagonist group (BD1047,PTZ+BD) according to the random number table,12 cases in each group.The rats were established animal model of neuropathic pain by spared nerve injury in the MOD,PTZ and PTZ+ BD group,and the rats were without any treatment in the CON group.After the establishment of animal model,the rats were injected with PTZ 2 mg/kg in the PTZ group;the rats wereinjected with BD1047 2 mg · kg-1 · d-1 in the PTZ group before the establishment of animal model and then injected with PTZ 2 mg/kg.Mechanical withdrawal reflex threshold (MWT) and heat pain were assessed at the first day before the treatment,and at 2,24 and 4,8 h after the treatment.After the final assessment of MWT and heat pain,the rats were anesthetized and sacrificed for the collection of L4-6 segmental spinal cord in each group.The mRNA and protein expression of Sig-1R,serine raceme (Srr) and phosphorylated-extracellular signal regulated kinase 1/2 (p-ERK1/2) were assessed by Western blot and RT-qPCR in the L4-6 segmental spinal cord of operation side.Results Compared with the CON group,postoperative pain was significantly increased in the rats of MOD group.The 50％ MWT and difference score of heat pain were decreased at 2,24 and 48 h after the treatment in the rats of PTZ group,but the time to leg-raising was increased.The 50％ MWT and difference score of heat pain were higher after the treatment in the PTZ + BD group than those in the MOD group,but lower than those in the PTZ group;the variation time to leg-raising was exactly in opposition to the variation of 50％ MWT and difference score of heat pain,suggesting that postoperative pain in the rats of PTZ+ BD group was slightly attenuated.Compared with the CON group,the expression of Sig-1R and Srr were both significantly up-regulated in the MOD,PTZ and PTZ + BD group.Compared with the MOD group,the expression of Sig-1R and Srr were both up-regulated in the PTZ group,but the expression of p-ERK 1/2 was decreased;the expression of Sig-1R and p-ERK1/2 were increased in the PTZ+BD group,but the expression of p-ERK1/2 between the MOD and PTZ+BD group were similar.The expression of Sig-1R and Srr were both lower in the PTZ+BD group than those in the PTZ group,and no difference was noted on the expression of p-ERK1/2 between the PTZ+BD and PTZ group.Conclusion Neuropathic pain can be attenuated by PTZ.Its mechanism probably associates with the up-regulation of Sig-1R and Srr expression,and down-regulation of p-ERK 1/2 expression.