CX3CR1参与NF-κB在脊髓水平调控大鼠炎性痛的研究

Regulation of inflammatory pain by NF-κB and CX3CR1 at the spinal cord of rats

目的:观察鞘内注射核因子-κB(nuclear factor-κB,NF-κB)抑制剂吡咯烷二硫氨基甲酸(pyrrolidine dithiocarbamate,PDTC)对单关节炎(monoarthritis,MA)模型大鼠痛阈值和脊髓中CX3C趋化因子受体-1(CX3C chemokine receptor1,CX3CR1)表达的影响。方法:48只成年雄性Sprague-Dawley大鼠鞘内置管成功后,随机分为4组,即sham组(假手术组)、MA组(单关节炎组)、PDTC预处理组及PDTC后处理组,每组大鼠均为12只。鞘内置管5d后制作MA模型。Sham组:左侧踝关节腔内注射50μL生理盐水,鞘内注射10μL生理盐水;MA组:左侧踝关节腔内注射50μL完全弗氏佐剂(complete Freund'sadjuvant,CFA),鞘内注射10μL生理盐水;PDTC预处理组:鞘内注射10μL PDTC(100μmol/L),30min后左侧踝关节腔内注射50μL CFA;PDTC后处理组:左侧踝关节腔内注射50μL CFA,30min后鞘内注射10μL PDTC(100μmol/L)。于术前及术后不同时间点测定痛阈值,用免疫组织化学法观察L5脊髓节段小胶质细胞的表达情况,并在鞘内注射后第1,3,5,7天取L4-L5脊髓膨大节段检测NF-κB mRNA和CX3CR1mRNA的表达。结果:与MA组相比,sham组、PDTC预处理组及PDTC后处理组的大鼠同侧后肢各时间点痛阈值明显升高,差异有统计学意义(P<0.05);与MA组相比,PDTC预处理组及PDTC后处理组大鼠的L5脊髓节段的小胶质细胞数量明显减少,脊髓中CX3CR1mRNA和NF-κB mRNA的表达均明显减少,差异均有统计学意义(均P<0.05)。结论:鞘内注射NF-κB抑制剂PDTC可以缓解CFA所致MA模型大鼠的痛觉异常。其机制可能与NF-κB信号通路通过调节CX3CR1的表达而参与炎性痛的发生、发展有关。

Objective To observe the effect of intrathecal injection of nuclear factor-κB （ NF-κB） inhibitor of pyrrolidine dithiocarbamate （ PDTC） on pain sensitivity thresholds and the expression of spinal cord CX3C chemokine receptor 1 （ CX3CR1 ） in monoarthritis （ MA ） model in rats. Methods Forty-eight Sprague-Dawley rats were randomly divided into 4 groups （ 12 each ） after successful intrathecal catheterization： （ 1 ） sham operation with physiological saline group （ the sham group） ; （ 2） MA with normal saline group （ the MA group） ; （ 3） 10 μL 100 μmol/L PDTC before MA （ the PDTC pre-treatment group） ; （ 4 ） MA before 10 μL 100 μmol/L PDTC （ the PDTC post-treatment group） . Normal saline or PDTC was injected 5 d after the intrathecal catheterization. Pain sensitivity thresholds were measured in the 4 groups before and after the intrathecal injection at different time points. Rat monoarthritis model was subsequently built by injecting complete Freund’s adjuvant （ CFA） into the left ankle joint of the rats. On day 3 after the intrathecal injection,expression of microglia in the L5 spinal cord segment was observed by immunohistochemical method,and the lumbar segments L4 - L5 of spinal cord were taken to perform RT-PCR to examine the expression of NF-κB mRNA and CX3 CR1 mRNA. Results Compared with the MA group,the pain sensitivity thresholds in the sham group,the PDTC pre-treatment group and the PDTC post-treatment group at each time point after the intrathecal injection increased significantly （ P 0. 05） ,while microglia in the L5 spinal cord segment decreased significantly （ P 0. 05 ） and expression of CX3CR1 mRNA and NF-κB mRNA in the lumbar segments L4 - L5 of spinal cord decreased significantly （ P 0. 05） . Conclusion The hyperalgesic effect of the CFA-induced model of monoarthritis can be relieved by intrathecal injection of NF-κB inhibitor PDTC. Its mechanism is possibly related to NF-κB signal pathway which is involved in the formation of inflammatory pain through regulating CX3CR1 expression.