鞘内注射GDNF对神经病理性痛大鼠脊髓背角p38MAPK蛋白表达的影响

目的 评价鞘内注射胶质细胞源性神经营养因子(GDNF)对神经病理性痛大鼠脊髓背角p38丝裂原活化蛋白激酶(p38MAPK)蛋白表达的影响.方法 取鞘内置管成功的健康雄性SD大鼠120只,周龄6周,体重180～200 g,随机分为4组(n=30):对照组(C组)、假手术组(S组)、神经病理性痛组(P组)和GDNF组.采用结扎L5.6脊神经的方法建立大鼠神经病理性痛模型.C组不给予任何处理;S组只暴露脊神经,但不结扎;P组脊神经结扎后鞘内注射生理盐水10μl,隔日1次,连续14 d;GDNF组脊神经结扎后鞘内注射GDNF 2μg,用生理盐水稀释至10μl,隔日1次,连续14 d.分别于脊神经结扎后3、7和14 d时,取10只大鼠,测定机械痛阈,然后处死,取脊髓背角,分别采用免疫组化法和蛋白质印迹法测定p38MAPK蛋白的表达水平.结果 与S组比较,P组和GDNF组机械痛阈降低,脊髓背角p38MAPK蛋白表达上调(P＜0.05或0.01);与P组比较,GDNF组机械痛阈升高,脊髓背角p38MAPK蛋白表达下调(P＜0.05或0.01).结论 鞘内注射GDNF可通过抑制脊髓背角p38MAPK蛋白的表达减轻大鼠神经病理性痛.     

鞘内注射DREAM-shRNA对神经病理性痛大鼠脊髓背角p-CREB表达的影响

目的 探讨鞘内注射转录因子下游调控元件拮抗因子-短发夹RNA(DREAM-shRNA)对神经病理性痛大鼠脊髓背角磷酸化环磷酸腺苷反应元件结合蛋白(p-CREB)表达的影响.方法 成年健康雄性SD大鼠,体重280～320 g,采用坐骨神经慢性压迫(CCI)法建立大鼠神经病理性痛模型.于CCI后第3天鞘内置管.取鞘内置管成功的大鼠24只,随机分为4组,每组6只,假手术组(S组):仅暴露坐骨神经,不结扎;神经病理性痛组(NP组):于CCI后第8天鞘内注射生理盐水10 μl;RNA干扰组(RNAi组):于CCI后第8天鞘内注射DREAM-shRNA 5 μl和牛理盐水5 μl;空白载体组(BV组):于CCI后第8天鞘内注射慢病毒空白载体5 μl和生理盐水5μl,各组连续注射7 d.于CCI前1 d(T0,基础状态)、CCI后第7～14天(T1-8)时测定机械痛阈.于CCI后第15天时测定脊髓背角绿色荧光蛋白(GFP)和p-CREB的表达水平.结果 与基础值比较,各组各时点机械痛阈降低(P<0.05或0.01);与T1时比较,NP组和BV组T5-8时机械痛阈降低,RNAi组T8时机械痛阈升高(P<0.05或0.01);与S组比较,NP组和BV组机械痛阈降低,RNAi组T2时机械痛阈降低,T8时升高,NP组、RNAi组和BV组脊髓背角p-CREB表达上调(P<0.05);与NP组比较,RNAi组T6-8时机械痛阈升高,脊髓背角p-CREB表达下调(P<0.05).RNAi组脊髓背角可见大量绿色荧光,即GFP表达阳性,其余3组脊髓背角未见绿色荧光,即GFP无表达.结论 鞘内注射DREAM-shRNA缓解大鼠神经病理性痛的机制可能与抑制脊髓背角p-CREB的表达有关.     

脊髓背角膜结合型补体调节蛋白表达在大鼠神经病理性痛形成中的作用

目的 评价脊髓背角膜结合型补体调节蛋白表达在大鼠神经病理性痛形成中的作用.方法 健康雄性SD大鼠,体重200 ～ 250 g.取48只鞘内置管成功的大鼠,采用随机数字表法,将其分为4组(n=12):假手术组(S组)、神经病理性痛组(NP组)、生理盐水组(NS组)和米诺环素组(M组).NP组、NS组和M组采用坐骨神经环形结扎法制备大鼠神经病理性痛模型,S组只分离坐骨神经后逐层缝合.M组于结扎坐骨神经前ld开始鞘内注射米诺环素50 μg,NS组鞘内注射等容量生理盐水,1次/d,连续7d.于结扎坐骨神经前1 d(T0)、结扎后1 d(T1)、3 d(T2)和7 d(T3)时测定大鼠机械痛阈和热痛阈.于T3痛阈测定结束后断头处死大鼠,取L4.5脊髓背角组织,分别用Western blot法和RT-PCR法检测CD46、CD55、CD59蛋白及其mRNA的表达水平.结果 与S组比较,NP组、NS组和M组T1-3时机械痛阈和热痛阈降低,T3时脊髓背角CD46、CD55、CD59蛋白及其mRNA表达下调(P＜0.05);与NS组和NP组比较,M组T2.3时机械痛阈和热痛阈升高,T3时脊髓背角CD46、CD55、CD59蛋白及其mRNA表达上调(P＜0.05).结论 脊髓背角膜结合补体调节蛋白表达下调,补体异常活化参与了大鼠神经病理性痛的形成.     

脊髓胶质细胞在小鼠骨癌痛形成中的作用

目的 评价脊髓胶质细胞在小鼠骨癌痛形成中的作用.方法 健康雄性C3H/He小鼠40只,周龄8～10周,体重18～22 g,随机分为4组(n=10):假手术组(S组)、骨癌痛组(B组)、PBS组(P组)和米诺环素组(M组).S组跟骨骨髓腔内注射PBS 10 μl;余3组跟骨骨髓腔内注射含2×105个骨纤维肉瘤细胞的PBS 10 μl制备骨癌痛模型,于造模前即刻开始PBS组鞘内注射PBS 5μl,M组鞘内注射米诺环素(用PBS溶解为0.2 mmol/L)5μl,1次/d,连续11 d.于造模前1 d、造模后即刻、3、5、7、9、11 d时测定机械痛阈;于造模后3、7、9、11 d机械痛阈测定结束后测定冷痛阈.痛阈测定结束后处死小鼠,取脊髓组织,测定神经胶质纤维酸性蛋白(GFAP)和CD11b的表达水平.结果 与S组比较,B组和P组造模后3-11 d时、M组造模后3、5 d时机械痛阈升高,B组、P组和M组造模后7～11 d时冷痛阈升高,脊髓CD11b和GFAP表达上调(P<0.05).与B组比较,M组造模后3-11 d时机械痛阈降低,造模后7-11 d时冷痛阈降低,脊髓CD11b和GFAP表达下调(P<0.05).结论 脊髓胶质细胞(星形胶质细胞和小胶质细胞)的激活参与了小鼠骨癌痛的形成.     

脊髓星形胶质细胞TLR3与大鼠痛觉过敏形成的关系

目的 评价脊髓星形胶质细胞Toll样受体3(TLR3)与大鼠痛觉过敏形成的关系.方法 雄性SD大鼠,体重180-250 g,取鞘内置管成功的大鼠126只,随机分为3组(n=42),正常对照组(C组);生理盐水组(NS组)鞘内注射生理盐水0.5 ml/kg,1次,d.连续7 d;痛觉过敏组(H组)腹腔注射米诺环素40me/kg+鞘内注射Poly(I:C)0.5 mg/kg,1次,d,连续7 d.各组于鞘内给药前1d和鞘内给药后1、3、5、7、10、14、21、28 d时测定机械痛阈和热痛阈;各组于鞘内给药后7 d时处死6只大鼠,取L4,5脊髓节段,采用免疫组化法测定脊髓背角胶质纤维酸性蛋白(GFAP)表达;各组于鞘内给药前1d和鞘内给药后1、7,14、21、28 d时各处死6只大鼠,取L4,5脊髓节段,采用RT-PCR法测定TLR3 mRNA表达.结果 与C组和Ns组比较,H组机械痛阈降低,脊髓背角GFAP和TLR3 mRNA表达上调(P<0.05).结论 TLR3与其特异性配体结合后,激活脊髓背角星形胶质细胞,诱发大鼠痛觉过敏.     

脊髓谷氨酸转运体、孤啡肽和脑源性神经营养因子在炎性痛大鼠吗啡耐受形成中的作用

目的 探讨脊髓谷氨酸转运体(GT)、孤啡肽(OFQ)和脑源性神经营养因子(BDNF)在炎性痛大鼠吗啡耐受形成中的作用.方法 健康雄性SD大鼠,8～ 10周龄,体重300 ～ 350 g,取鞘内置管成功的雄性SD大鼠20只,采用随机数字表法,将其随机分为4组(n=5):生理盐水组(NS组)、炎性痛组(IP组)、吗啡组(M组)和GT激动剂riluzole组(R组).NS组于左后足踝关节腔注射生理盐水50μl,其余3组注射完全弗氏佐剂50 μl.3d后,NS组和IP组鞘内注射生理盐水10 μl;M组鞘内注射吗啡10 μg;R组鞘内注射riluzole 10 μg,30 min后注射吗啡10 μg.注射药物容量均为10μl,2次/d,连续7d.于鞘内给药前、鞘内给药2、4、6d和鞘内给药结束后1 d(T0-4)时测定机械痛阈.于T4时痛阈测定后取左侧脊髓背角,采用RT-PCR法测定OFQ mRNA和BDNF mRNA的表达.结果 与NS组比较,IP组机械痛阈降低,脊髓背角OFQ mRNA及BDNF mRNA表达上调(P＜0.05或0.01);与IP组比较,M组T1,2时机械痛阈升高,脊髓背角OFQ mRNA及BDNF mRNA表达上调(P＜0.05或0.01),T3,4时机械痛阈差异无统计学意义(P＞0.05);与M组比较,R组机械痛阈升高,脊髓背角OFQ mRNA及BDNF mRNA表达下调(P＜0.05或0.01).结论 炎性痛大鼠长期注射吗啡时脊髓GT功能降低,导致谷氨酸水平升高和OFQ、BDNF表达上调之间的失衡,可能在吗啡耐受形成中起到一定作用.     

乳铁蛋白对神经病理性痛大鼠脊髓背角PKG活性的影响

目的 探讨乳铁蛋白对神经病理性痛大鼠脊髓背角cGMP依赖性蛋白激酶(PKG)活性的影响.方法 雄性SD大鼠32只,体重200～250 g,随机分为4组(n=8):假手术组仅分离坐骨神经,不结扎,鞘内注射生理盐水10μl+50%二甲基亚砜(DMSO)10μl;余3组采用结扎坐骨神经的方法制备大鼠神经病理性痛模型,神经病理性痛组鞘内注射生理盐水10μl+50%DMSO10μl;乳铁蛋白组鞘内注射乳铁蛋白100μg+50%DMS010μl;PKG抑制剂KT5823组鞘内注射乳铁蛋白100μg+KT582310μl.给药后180 min内每隔30 min以热刺激法测定大鼠缩爪潜伏期,随后处死大鼠取脊髓背角,采用免疫荧光法检测PKG活性,并行定量分析.结果 与神经病理性痛组和KT5823组相比,乳铁蛋白组缩爪潜伏期延长,乳铁蛋白组脊髓背角PKG活性升高(P＜0.05);神经病理性痛组与KT5823组上述指标比较差异无统计学意义(P＞0.05).结论 乳铁蛋白可通过抑制脊髓背角PKG活性减轻大鼠神经病理性痛.     

鞘内注射DREAM-shRNA对神经病理性痛大鼠的镇痛效应

目的 评价鞘内注射转录因子下游调控元件拮抗因子-短发夹RNA(DREAM-shRNA)对神经病理性痛大鼠的镇痛效应.方法 健康雄性SD大鼠,体重280-320g,采用坐骨神经慢性缩窄性损伤(CCI)法建立大鼠神经病理性痛模型,于CCI后第3天鞘内置管.取鞘内置管成功的大鼠24只,随机分为4组,每组6只,假手术组(Sham组):仅暴露坐骨神经,不结扎;神经病理性痛组(NP组):于CCI后第8天鞘内注射生理盐水10μl;RNA干扰组(RNAi组):于CCI后第8天鞘内注射含DREAM-shRNA的慢病毒5μl、生理盐水5μl;空白载体组(BV组):于CCI后第8天鞘内注射慢病毒空白载体5μl、生理盐水5μl,连续注射7d.于CCI前1d(基础状态)、CCI后第7～14天(T1-8)测定热痛阈和机械痛阈,于CCI后第15天测定脊髓背角绿色荧光蛋白(GFP)的表达水平.结果 与基础值比较,NP组和BV组热痛阈降低,Sham组T1-4时热痛阈降低,RNAi组T1-4,6时热痛阈降低,4组CCI后各时点机械痛阈降低(P<0.05或0.01);与T1时比较,NP组和BV组其余时点热痛阈和机械痛阈降低.RNAi组T3-5,时热痛阈降低,T1时热痛阈和机械痛阈升高(P<0.05或0.01);与Sham组比较.NP组和BV组热痛阈和机械痛阈降低,RNAi组T2时机械痛阈降低,T5时升高(P<0.05),热痛阈差异无统计学意义(P>0.05);与NP组比较.RNAi组热痛阈和机械痛阈升高(P<0.05).仅RNAi组脊髓背角有GFP表达,其余3组脊髓背角未见GFP表达.结论 鞘内连续注射DREAM-shRNA可在一定程度上缓解大鼠神经病理性痛.     

5-HT5A受体在长春新碱致神经病理性痛大鼠脊髓背角星形胶质细胞活化中的作用

目的 评价5-羟色胺5A受体(5-HT5AR)在长春新碱致神经病理性痛大鼠脊髓背角星形胶质细胞活化中的作用.方法 雄性成年SD大鼠40只,体重180～200 g,随机分为4组(n=10):对照组(C组)、神经病理性痛组(P组)、空载体腺病毒组(B组)和siRNA重组腺病毒载体组(S组).C组腹腔注射生理盐水1 ml;P组、B组和S组第1～5天和第8～12天每天定时腹腔注射0.1 mg/kg长春新碱建立大鼠神经病理性痛模型.腹腔给药结束第2天测定机械痛阈,然后P组、B组和S组分别鞘内注射人工脑脊液、空载体腺病毒和siRNA重组腺病毒载体25μl.鞘内给药后第7天测定机械痛阈,然后处死大鼠,取L4.5脊髓组织,测定脊髓背角5-HT5AR及胶原纤维酸性蛋白(GFAP)的表达.结果 与C组比较,P组、B组和S组各时点机械痛阈降低,脊髓背角5-HT5AR和GFAP的表达均上调(P＜0.05);与P组比较,S组鞘内给药后第7天机械痛阈降低,脊髓背角5-HT5AR表达下调,GFAP表达上调(P＜0.05),B组上述指标差异无统计学意义(P＞0.05).结论 5-HT5AR参与了星形胶质细胞活化的抑制过程,从而减轻长春新碱致大鼠神经病理性痛.     

神经病理性痛大鼠脊髓背角星形胶质细胞NF-κB活性的变化

目的 观察神经病理性痛大鼠脊髓背角星形胶质细胞NF-κB活性的变化,以探讨脊髓星形胶质细胞调控神经病理性痛时胞内可能的信号转导通路机制.方法 雄性SD大鼠16只,月龄2～3 71,体重220～280 g,随机分为2组(n=8):假手术组(S组)和神经病理性痛组(CCI组).CCI组采用慢性压迫性损伤法制备大鼠慢性神经病理性痛模型,S组仅暴露坐骨神经.分别于术前1 d和术后7 d测定机械痛阈和热痛阈,术后第7天测定痛阈后处死大鼠,取脊髓,记录腰段脊髓背角星形胶质细胞核内NF-κBp65的免疫反应阳性细胞数.结果 与术前1 d比较,CCI组大鼠术后7 d机械痛阈和热痛阈降低(P<0.05).与S组比较,CCI组大鼠术后7 d机械痛阈和热痛阈降低,术侧脊髓背角星形胶质细胞NF-κBp65免疫阳性细胞数增多(P<0.05).结论 脊髓背角星形胶质细胞参与大鼠神经病理性痛的调控,其机制可能与NF-κB信号转导通路有关.     

脊髓小胶质细胞活化在大鼠术后持续性痛中的作用

目的 探讨脊髓小胶质细胞活化在大鼠术后持续性痛中的作用.方法选择鞘内置管成功的雄性SD大鼠72只,体重200～250 g,采用随机数字表法,将其随机分为3组(n=24):假手术组、皮肤肌肉切口牵拉组(SMIR组)和米诺环素组.采用皮肤肌肉切口牵拉法建立大鼠术后持续性痛模型,假手术组和SMIR组于术前30 min和术后1～3 d鞘内注射人工脑脊液20 μl,1次,d;米诺环素组于术前30 min和术后1～3 d鞘内注射米诺环素10 μl,1次/d,并在每次注药后经导管注射人工脑脊液10 μl冲洗导管.于术前1 d及术后3、7、12、22和32 d时测定机械缩足反射阈值(MWT),各时点MWT测定结束后,随机取4只大鼠,测定脊髓背角小胶质细胞特异性标记物Iba-1的表达和计数小胶质细胞.结果 与假手术组比较,SMIR组和米诺环素组术后3～22 d时MWT降低,术后3、7 d时脊髓背角Iba-1表达和小胶质细胞计数升高(P＜0.05);与SMIR组比较,米诺环素组术后3～22 d时MWT升高,术后3、7 d时脊髓背角Iba-1表达和小胶质细胞计数降低(P＜0.05).结论 脊髓小胶质细胞的活化参与了大鼠术后持续性痛的形成.

Abstract：

Objective To investigate the role of microglial activation in spinal cord in a rat model of persistent postoperative pain evoked by skin/muscle incision and retraction (SMIR) .Methods Seventy-two male SD rats weighing 200-250 g in which intrathecal (IT) catheter was successfully inserted were randomly divided into 3 groups ( n = 24 each) : group sham operation; group SMIR and group SMIR + FT minocycline (a specific microglia inhibitor) . The rat model of persistent postoperative pain evoked by SMIR was established according to the method described by Flatters. Pain behavior was assessed by paw mechanical withdrawal threshold ( MWT) to von Frey filament stimulation at 1 day before (T0,baseline) and 3, 7, 12, 22 and 32 days after operation (T1-5,) . Four animals were sacrificed at each time point in each group for detection of the expression of Iba-1 (a specific marker of microglia) in the spinal dorsal horn by immunofluorescence and the microglia was counted. Results MWT was significantly decreasedat T1-4, while the expression of Iba-1 and microglia counts in the spinal dorsal horn were significantly increased at T1, 2 by SMIR in group Ⅱ. IT minocycline significantly attenuated the hyperalgesia induced by SMIR at T1-4 and decreased Iba-1 expression and microglia counts at T1,2 in group Ⅲ. Conclusion Microglial activation in the spinal cord plays an important role in the development and maintenance of SMIR-evoked persistent postoperative pain in rats.     

鞘内注射舒芬太尼对神经病理性痛大鼠脊髓背角NMDA受体及CGRP表达的影响

目的 评价鞘内注射舒芬太尼对神经病理性痛大鼠脊髓背角N-甲基-D-天冬氨酸(NMDA)受体及降钙素相关基因肽(CGRP)表达的影响.方法 雄性SD大鼠36只,体重220～280 g,随机分为4组(n=9):正常对照组(C组)、假手术组(S组)、坐骨神经分支选择性损伤组(SNI组)和舒芬太尼+坐骨神经分支选择性损伤组(S+SNI组).SNI组和S+SNI组制备SNI模型,S+SNI组在SNI术后14 d内每天鞘内注射舒芬太尼1 μg(用生理盐水稀释至10 μl),其余各组给予等容量生理盐水.于SNI给药前2 d(基础状态)及给药1、2、7、14 d测定机械痛阈和热缩足潜伏期,分别于给药2、7、14 d测定痛阈后立即处死3只大鼠,采用免疫组化法测定L5节段脊髓背角NMDA受体和CGRP表达水平.结果 与C组和S组比较,SNI组机械痛阚降低,NMDA受体和CGRP表达上调(P<0.01),热缩足潜伏期差异无统计学意义(P>0.05).与SNI组比较,S+SNI组机械痛阈升高,热缩足潜伏期延长,NMDA受体和CGRP表达下调(P<0.01).结论 鞘内注射舒芬太尼可抑制脊髓背角NMDA受体和CGRP表达上调,从而减轻大鼠神经病理性痛.     

Increased expression of cyclooxygenase and nitric oxide isoforms, and exaggerated sensitivity to prostaglandin E2, in the rat lumbar spinal cord 3 days after L5-L6 spinal nerve ligation

BACKGROUND: Spinal prostaglandins seem to be important in the early pathogenesis of experimental neuropathic pain. Here, the authors investigated changes in the expression of cyclooxygenase and nitric oxide synthase (NOS) isoforms in the lumbar, thoracic, and cervical spinal cord and the pharmacologic sensitivity to spinal prostaglandin E2 (PGE2) after L5-L6 spinal nerve ligation (SNL). METHODS: Male Sprague-Dawley rats, fitted with intrathecal catheters, underwent SNL or sham surgery 3 days before experimentation. Paw withdrawal threshold was monitored for up to 20 days. Immunoblotting, spinal glutamate release, and behavioral testing were examined 3 days after SNL. RESULTS: Allodynia (paw withdrawal threshold < or = 4 g) was evident 1 day after SNL and remained stable for 20 days. Paw withdrawal threshold was unchanged (P > 0.05) from baseline (> 15 g) after sham surgery except for a small but significant decrease on day 20. Cyclooxygenase 2, neuronal NOS, and inducible NOS were significantly increased in the ipsilateral lumbar dorsal horn after SNL. Expression in the contralateral dorsal horn and ventral horns (lumbar segments) or bilaterally (thoracic and cervical segments) was unchanged from sham controls. This was accompanied by a significant decrease in both the EC50 of PGE2-evoked glutamate release and the ED50 of PGE2 on brush-evoked allodynia. Enhanced sensitivity to PGE2 was localized to lumbar segments of SNL animals and attenuated by SC-51322 or S(+)-ibuprofen, but not R(-)-ibuprofen (100 mum). CONCLUSION: The increased expression of cyclooxygense-2, neuronal NOS, and inducible NOS and the enhanced sensitivity to PGE2 in spinal segments affected by SNL support the hypothesis that spinal prostanoids play an early pathogenic role in experimental neuropathic pain.     

Increased Expression of Cyclooxygenase and Nitric Oxide Isoforms, and Exaggerated Sensitivity to Prostaglandin E2, in the Rat Lumbar Spinal Cord 3 Days after L5-L6 Spinal Nerve Ligation

Background: Spinal prostaglandins seem to be important in the early pathogenesis of experimental neuropathic pain. Here, the authors investigated changes in the expression of cyclooxygenase and nitric oxide synthase (NOS) isoforms in the lumbar, thoracic, and cervical spinal cord and the pharmacologic sensitivity to spinal prostaglandin E2 (PGE2) after L5-L6 spinal nerve ligation (SNL).

Methods: Male Sprague-Dawley rats, fitted with intrathecal catheters, underwent SNL or sham surgery 3 days before experimentation. Paw withdrawal threshold was monitored for up to 20 days. Immunoblotting, spinal glutamate release, and behavioral testing were examined 3 days after SNL.

Results: Allodynia (paw withdrawal threshold <= 4 g) was evident 1 day after SNL and remained stable for 20 days. Paw withdrawal threshold was unchanged (P > 0.05) from baseline (> 15 g) after sham surgery except for a small but significant decrease on day 20. Cyclooxygenase 2, neuronal NOS, and inducible NOS were significantly increased in the ipsilateral lumbar dorsal horn after SNL. Expression in the contralateral dorsal horn and ventral horns (lumbar segments) or bilaterally (thoracic and cervical segments) was unchanged from sham controls. This was accompanied by a significant decrease in both the EC50 of PGE2-evoked glutamate release and the ED50 of PGE2 on brush-evoked allodynia. Enhanced sensitivity to PGE2 was localized to lumbar segments of SNL animals and attenuated by SC-51322 or S(+)-ibuprofen, but not R(-)-ibuprofen (100 [mu]m).     

Spinal Prostaglandins Facilitate Exaggerated A- and C-fiber-mediated Reflex Responses and Are Critical to the Development of Allodynia Early after L5-L6 Spinal Nerve Ligation

Background: Spinal prostaglandins are important in the early pathogenesis of spinal nerve ligation (SNL)-induced allodynia. This study examined the effect of SNL on the expression of cyclooxygenase (COX)-1, COX-2, and prostaglandin E2 receptors in the rat lumbar spinal cord, and the temporal and pharmacologic relation of these changes to the exaggerated A- and C-fiber-mediated reflex responses and allodynia, 24 h after injury.

Methods: Male Sprague-Dawley rats, fitted with intrathecal catheters, underwent SNL or sham surgery. Paw withdrawal threshold, electromyographic analysis of the biceps femoris flexor reflex, and immunoblotting of the spinal cord were used.

Results: Both allodynia (paw withdrawal threshold of <= 4 g) and exaggerated A- and C-fiber-mediated reflex responses (i.e., decrease in activation threshold, increase in evoked activity, including windup; P < 0.05) were evident 24 h after SNL but not sham surgery. Allodynic animals exhibited significant increases in prostaglandin E2 receptor (subtypes 1-3) and COX-1 (but not COX-2) expression in the ipsilateral lumbar dorsal horn. The corresponding ventral horns and contralateral dorsal horn were unchanged from sham controls. Exaggerated A- and C-fiber-mediated reflex responses were significantly attenuated by intrathecal SC-560 or SC-51322, but not SC-236, given 24 h after SNL.     

脊髓神经元型一氧化氮合酶在大鼠神经病理性痛中的作用

目的 探讨脊髓神经元型一氧化氮合酶(nNOS)在大鼠神经病理性痛中的作用.方法 健康雄性SD大鼠40只,体重220～280 g,采用结扎坐骨神经干的方法建立坐骨神经慢性压迫性损伤(CCI)模型.随机分为4组(n=10),Ⅰ组及Ⅱ组暴露坐骨神经干,分别于术后1 d开始鞘内注射选择性nNOS抑制剂7-NI 60 μg[溶于20%二甲基亚砜(DMSO)]10μl)、20%DMSO 10μl,1次/d,连续6d;Ⅲ组及Ⅳ组制备CCI模型,分别于术后1 d开始鞘内注射7-NI 60μg(溶于20%DMSO 10μl)、20%DMSO 10 μl,1次/d,连续6 d.分别于CCI前1 d、CCI后1、3、5、7 d时测定大鼠机械痛阈和热痛阈.于CCI后7 d,各组分别取5只大鼠,取术侧L_(4～6)背根神经节,分别采用实时定量PCR和Western blot法测定nNOS mRNA及蛋白的表达水平.结果 与Ⅰ组和Ⅱ组比较,T_(1～4)时Ⅲ组和Ⅳ组术侧后肢机械痛阈和热痛阈降低(P＜0.05),背根神经节nNOS蛋白及mRNA的表达上调(P＜0.05);与Ⅲ组比较,T_(1～4)时Ⅳ组机械痛阈和热痛阈降低,背根神经节nNOS蛋白及mRNA的表达上调(P＜0.05).结论 脊髓nNOS参与了大鼠神经病理性痛的形成.     

Spinal prostaglandins facilitate exaggerated A- and C-fiber-mediated reflex responses and are critical to the development of allodynia early after L5-L6 spinal nerve ligation

BACKGROUND: Spinal prostaglandins are important in the early pathogenesis of spinal nerve ligation (SNL)-induced allodynia. This study examined the effect of SNL on the expression of cyclooxygenase (COX)-1, COX-2, and prostaglandin E2 receptors in the rat lumbar spinal cord, and the temporal and pharmacologic relation of these changes to the exaggerated A- and C-fiber-mediated reflex responses and allodynia, 24 h after injury. METHODS: Male Sprague-Dawley rats, fitted with intrathecal catheters, underwent SNL or sham surgery. Paw withdrawal threshold, electromyographic analysis of the biceps femoris flexor reflex, and immunoblotting of the spinal cord were used. RESULTS: Both allodynia (paw withdrawal threshold of < or = 4 g) and exaggerated A- and C-fiber-mediated reflex responses (i.e., decrease in activation threshold, increase in evoked activity, including windup; P < 0.05) were evident 24 h after SNL but not sham surgery. Allodynic animals exhibited significant increases in prostaglandin E2 receptor (subtypes 1-3) and COX-1 (but not COX-2) expression in the ipsilateral lumbar dorsal horn. The corresponding ventral horns and contralateral dorsal horn were unchanged from sham controls. Exaggerated A- and C-fiber-mediated reflex responses were significantly attenuated by intrathecal SC-560 or SC-51322, but not SC-236, given 24 h after SNL. CONCLUSION: These results provide further evidence that spinal prostaglandins, derived primarily from COX-1, are critical in the exaggeration of A- and C-fiber input and allodynia, 24 h after SNL.     

Intrathecal lidocaine reverses tactile allodynia caused by nerve injuries and potentiates the antiallodynic effect of the COX inhibitor ketorolac

BACKGROUND: Systemic lidocaine and other local anesthetics reduce hypersensitivity states induced by both acute inflammation and peripheral nerve injury in animals and produce analgesia in some patients with chronic pain. The mechanisms underlying the antiallodynic effect of systemic lidocaine are unclear, although most focus is on peripheral mechanisms. Central mechanisms, particularly at the spinal dorsal horn level, are less known. In this study, the authors aimed to determine whether intrathecal lidocaine has an antiallodynic effect on established mechanical allodynia in two well-characterized neuropathic pain rat models: partial sciatic nerve ligation (PSNL) and spinal nerve ligation (SNL). METHODS: Lidocaine (100-300 micro g) was intrathecally injected in PSNL and SNL rats. The withdrawal threshold of both hind paws in response to mechanical stimulation was measured using a series of calibrated von Frey filaments. RESULTS: This single injection reduced ongoing tactile allodynia in PSNL and SNL rats. The antiallodynic effect of intrathecal lidocaine lasted longer in PSNL (> 3 days) than in SNL rats (< 3 days). Intraperitoneal lidocaine (300 micro g) had no effect on tactile allodynia in PSNL rats. In SNL rats, prior intrathecal lidocaine (200 and 300 micro g) potentiated the antiallodynic effect of intrathecal ketorolac, a nonselective cyclooxygenase inhibitor. Intrathecal ketorolac alone had no antiallodynic effect on SNL rats. However, prior intrathecal lidocaine (100 micro g) failed to potentiate the antiallodynic effect of intrathecal ketorolac. CONCLUSION: The authors' data suggest that intrathecal lidocaine possibly suppressed the hyperexcitability of the dorsal horn neurons and likely interacted with eicosanoid systems in the spinal dorsal horn.