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目的:观察鞘内注射p38MAPK磷酸化抑制剂SB203580对慢性坐骨神经结扎(chronic constriction injury,CCI)大鼠热痛阈及脊髓背角P2X_4、P2X_7、P2Y_(12)、P2Y_(13)受体mRNA表达变化的影响。方法:成年SD大鼠随机分为5组(n=8):假手术组(sham组)、CCI模型组(CCI+鞘内注射0.005%DMSO生理盐水)、CCI+鞘内注射SB203580 1μmol/L组、CCI+鞘内注射SB203580 10μmol/L组、CCI+鞘内注射SB203580 50μmol/L组。CCI模型组及CCI+SB203580处理组大鼠均于鞘内置管7 d后行慢性坐骨神经结扎,连续14 d鞘内注射0.005%DMSO生理盐水或SB203580(1,10,50μmol/L),2次/d,分别在术前1 d、术后第1,3,5,7,10,14 d测定给药1 h后热缩足潜伏期(TWL);并在第3,7,14 d取大鼠脊髓背角进行荧光定量PCR,观察脊髓背角P2X_4、P2X_7、P2Y_(12)、P2Y_(13)受体mRNA的表达变化。结果:CCI术后大鼠即形成稳定的热痛敏,与sham组相比,CCI模型组大鼠术后TWL明显缩短(P<0.05);与CCI模型组相比,CCI+SB203580 10,50μmol/L处理组大鼠随药物剂量增加,TWL延长更为明显(P<0.05)。荧光定量PCR结果显示:与sham组相比,CCI模型组第3,7,14 d,P2X_4、P2X_7、P2Y_(12)、P2Y_(13)受体mRNA的表达上调(P<0.05);给予SB203580 50μmoL/L后,大鼠脊髓背角P2X_7、P2Y_(13)受体mRNA表达有所下调(P<0.05),但P2X_4和P2Y_(12)受体mRNA表达没有明显变化。结论:鞘内注射p38MAPK磷酸化抑制剂SB203580可以明显抑制CCI大鼠热痛敏行为学表现,其机制与抑制脊髓背角P2X_7、P2Y_(13)受体mRNA表达有关。这提示脊髓背角小胶质细胞p38MAPK活化后上调P2X_7和P2Y_(13)受体基因转录水平可能是p38MAPK在脊髓水平参与伤害性信息传递的机制之一。
PURPOSE: To observe the effects of intrathecal injection of p38MAPK phosphorylation inhibitor SB203580 on the pain threshold and P2X_4, P2X_7, P2Y_ (12) and P2Y_ (13) mRNA expressions in the spinal cord of rats with chronic constriction injury (CCI) Impact. Methods: Adult SD rats were randomly divided into 5 groups (n = 8): sham group, CCI model group (CCI + intrathecal injection of 0.005% DMSO saline), CCI + intrathecal injection of SB203580 1μmol / CCI + intrathecal SB203580 10μmol / L group, CCI + intrathecal SB203580 50μmol / L group. The rats in CCI model group and CCI + SB203580 group were subjected to chronic sciatic nerve ligation for 7 days after intrathecal administration, and injected with 0.005% DMSO saline or SB203580 (1, 10, 50μmol / L) twice a day for 14 days. d, the thermal contraction foot latency (TWL) was measured at 1 day before operation and at 1, 3, 5, 7, 10 and 14 days after operation, respectively. The dorsal horn of spinal cord was quantified by real-time PCR, and the expressions of P2X_4, P2X_7, P2Y_ (12) and P2Y_ (13) mRNA in spinal dorsal horn were observed. Results: Compared with the sham group, the TWL in the CCI model group was significantly shorter (P <0.05) after CCI. Compared with the CCI model group, CCI + SB203580 10 and 50μmol / L treatment group with the drug dose increased, TWL prolonged even more significant (P <0.05). The result of real-time PCR showed that the mRNA expressions of P2X_4, P2X_7, P2Y_ (12) and P2Y_ (13) receptors in CCI model group were significantly increased (P <0.05) The mRNA expression of P2X_7 and P2Y_ (13) receptors in spinal dorsal horn was decreased (P <0.05) at 50μmol / L, but the mRNA expression of P2X_4 and P2Y_ (12) receptors did not change significantly. Conclusion: Intrathecal injection of SB203580, a phosphorylation inhibitor of p38MAPK, can significantly inhibit the thermo-sensitization in CCI rats. The mechanism is related to the inhibition of P2X_7 and P2Y_ (13) mRNA expression in spinal dorsal horn. This suggests that upregulation of P2X_7 and P2Y_ (13) receptor gene transcription levels by p38 MAPK activation in the spinal dorsal horn microglia may be one of the mechanisms by which p38MAPK participates in nociceptive transmission at spinal level.