瑞芬太尼诱发切口痛大鼠痛觉过敏与脊髓谷氨酸转运体-1和谷氨酰胺合成酶功能的关系

Relationship between remifentanil-induced hyperalgesia and function of nitrated glutamate transpor-tor-1 and glutamine synthetase in spinal cord of rats with incisional pain

目的 探讨瑞芬太尼诱发切口痛大鼠痛觉过敏时脊髓谷氨酸转运体-1(GLT-1)和谷氨酰胺合成酶(GS)功能的变化.方法 取尾静脉置管成功的雄性SD大鼠32只,体重260~280 g,2~3月龄,采用随机数字表法分为4组(n=8):对照组(C组)、切口痛组(I组)、瑞芬太尼组(R组)和瑞芬太尼+切口痛组(RI组).C组静脉输注生理盐水0.1 ml·kg-1·min-160 min;I组建立切口痛模型,同时尾静脉输注生理盐水0.1 ml·kg-1·min-160 min;瑞芬太尼组(R组)尾静脉输注瑞芬太尼1.0μg·kg-1·min-160 min;RI组建立切口痛模型,尾静脉输注瑞芬太尼1.0μg·kg-1·min-160 min.于输注瑞芬太尼或生理盐水前24 h(T0)、停止输注瑞芬太尼或生理盐水后2、6、24和48 h(T1-4)时测定机械缩足反应阈(MWT)和热缩足潜伏期(TWL).最后1次测定痛阈后处死大鼠,取脊髓L4-6节段,采用Western blot法测定脊髓GLT-1和GS的表达水平,采用免疫沉淀联合Western blot法测定脊髓硝基化GLT-1(nGLT-1)和硝基化GS(nGS)的表达水平.结果 与C组比较,I组、R组和RI组T1-4时MWT降低,TWL缩短,脊髓GLT-1和GS表达下调,nGLT-1和nGS表达上调,nGLT-1∕GLT-1比值和nGS∕GS比值升高(P<0.05).与I组和R组比较,RI组T1-4时MWT降低,TWL缩短,脊髓GLT-1和GS表达下调,nGLT-1比值和nGS表达上调,nGLT-1∕GLT-1和nGS∕GS比值升高(P<0.05).结论 瑞芬太尼诱发切口痛大鼠痛觉过敏形成的机制可能与脊髓GLT和GS功能受损有关.

Objective To investigate the relationship remifentanil-induced hyperalgesia and function of nitrated glutamate transportor-1(GLT-1)and glutamine synthetase (GS)in the spinal cord of rats with incisional pain.Methods Thirty-two male Sprague-Dawley rats,weighing 260-280g,aged 2-3 months,in which caudal catheters were successfully implanted,were divided into 4 groups (n=8 each)using a random number table method:control group (group C),incisional pain group(group I),remifentanil group (group R)and remifentanil plus incisional pain group (group RI).Normal saline was intravenously infused for 60 min at 0.1ml·kg^-1·min^-1 in group C.The model of incisional pain was estab lished,and normal saline was simultaneously infused for 60 min via the tail vein at 0.1ml·kg^-1·min^-1 in group I.Remifentanil was infused for 60 min via the tail vein at 1.0μg·kg^-1·min^-1 in group R.The model of incisional pain was established,and remifentanil was infused for 60 min via the tail vein at 1.0 μg ·kg^-1·min^-1 in group RI.The mechanical paw withdrawal threshold (MWT)and thermal paw withdrawal latency (TWL)were measured at 24h before infusion of remifentanil or normal saline (TO )and at 2,6,24 and 48h after infusion (T1-4).The rats were sacrificed after the last measuremnet of pain threshold,and the L4-6 segment of the spinal cord was removed for determination of the expression of GLT-1 and GS (by Western blot)and expression of nitrated GLT-1(nGLT-1)and nitrated GS (nGS)(by Western blot).Ratios of nGLT-1/GLT-1 and nGS/GS were calculated.Results Compared with group C,the MWT was significantly decreased and TWL was shortened at Tt.4,the expression of GLT-1 and GS was down-regulated,the expression of nGLT-1 and nGS was up-regulated,and ratios of nGLT-1/GLT-1 and nGS/GS were increased in I,R and RI groups (P<0.05).Compared with group I and group R,the MWT was signifi- cantly decreased and TWL was shortened at T14,the expression of GLT-1and GS was down-regulated,the expression of nGLT-1 and nGS was up-regulated,and ratios of nGLT-1/GLT-1 and nGS/GS were increased in group RI (P<0.05).Conclusion The mechanism of remifentanil-induced hyperalgesia may be related to impaired function of GLT-I and GS in the spinal cord of rats with incisional pain.