蛋白激酶Cε对大鼠背根神经节持续受压后背角星型胶质细胞激活和机械痛敏的影响

关键词：脊髓背角  蛋白激酶C  星型胶质细胞  背根神经节持续受压

Keywords:spinal cord horn  protein kinase Cε  astrocytes  chronic compression of the dorsal root ganglion

摘要：

      摘要 目的：探讨大鼠背根神经节持续受压(chronic compression of the dorsal root ganglion，CCD)后，脊髓背角星型胶质细胞的激活情况，以及PKCε是否可以通过调节星型胶质细胞的活性而参与CCD后神经病理性疼痛。 方法：将大鼠随机分为 6组，每组大鼠8只：假手术组、CCD7天组、CCD14天组、CCD7天+BIM I组、CCD+DMSO组、CCD+PDBu组，分别通过鞘内注射不同药物，或对正常大鼠鞘注DMSO/PDBu后，测量大鼠机械刺激缩爪阈值（paw withdrawal mechanical threshold，PWMT）的变化，利用Western Blot技术检测脊髓背角PKCε和GFAP蛋白表达的变化，利用免疫荧光技术检测脊髓背角星型胶质细胞激活情况。 结果：CCD术后第4天，鞘内注射PKCε的激动剂PDBu 1—4h，明显降低CCD大鼠PWMT（P<0.05），而给予BIM I 1—4h，可升高CCD大鼠PWMT（P<0.05）。从CCD术后第4天起，连续3天鞘注BIM I，可明显缓解大鼠的机械痛敏（4天，P<0.05），但从停止注射后镇痛作用消失（P>0.05）。与假手术组比较，CCD后7天和14天，手术侧背角PKCε和GFAP表达升高，差异有显著性意义(P<0.05)，星型胶质细胞激活增加，而注射BIM I可明显抑制PKCε和GFAP表达(P<0.05)和星型胶质细胞激活。PDBu可导致正常大鼠PWMT明显降低（P<0.05），GFAP蛋白质表达量增加（P<0.05），促进星型胶质细胞激活。 结论：大鼠背根神经节持续受压后，机械痛阈下降的同时，手术侧脊髓背角内PKCε和GFAP蛋白表达上调，星型胶质细胞激活增加。PKCε可能通过调节星型胶质细胞激活参与CCD后病理性神经痛的中枢敏化机制。

Abstract:

      Abstract Objective：To investigate the effect of protein kinase Cε (PKCε) on pain behavior and spinal astrocytes activation after chronic compression of the dorsal root ganglion (CCD) of rats. Method: Wistar rats weighting 200—220g were randomly divided into six groups(n=8)：sham operation group，CCD 7 days group，CCD 14 days group，CCD 7 days+Bisindolylmaleimide I (BIM I) group， CCD+DMSO group， CCD+Phorbol 12，13-dibutyrate (PDBu) group. Drugs were given by intrathecal injection after CCD model established. At 1， 4，7，and 14 days after CCD operation，the paw withdrawal mechanical threshold (PWMT) was tested. Then the protein expression of PKCε and GFAP in ipsilateral spinal dorsal horn was tested by Western Blot and the activation of astrocytes was detected by immunofluorescence technique. Result: The mechanical allodynia in CCD rats was attenuated by intrathecal administration of the PKC inhibitor BIM I and aggravated by its activator PMA at 4th day after CCD. The protein expression of PKCε and GFAP in the spinal dorsal horn and the activation of astrocytes were increased 7 days and 14 days after CCD (P<0.05)， which was suppressed by BIM I. Pretreated with PDBu could also significantly increase PMWT and the protein expression of GFAP (P<0.05)， as well as the activation of astrocytes in spinal dorsal horn in normal rats. Conclusion: After CCD operation，the PMWT and the protein expression of PKCε and GFAP (P<0.05) were significantly increased， as well as the activation of astrocytes in spinal dorsal horn. PKCε may take part in the central sensitization mechanism of neuropathic pain of CCD rats via regulating the activation of astrocytes.