血管紧张素Ⅱ2型受体拮抗剂EMA401对神经性疼痛模型大鼠的镇痛效应及机制研究

摘要

目的：观察血管紧张素Ⅱ2型受体拮抗剂EMA401对坐骨神经慢性压迫性损伤（ chronic constric－tion injury，CCI）模型大鼠的镇痛效应及背根神经节（dorsal root ganglion，DRG）生长相关蛋白43（growth－associated protein－43，GAP－43）、蛋白激酶C（protein kinase C，PKC）和钙调素（calmodulin，CaM）表达的影响。方法：采用SD大鼠建立CCI模型，随机分为4组：模型组（ model组），给予等体积生理盐水灌胃；低剂量组，按照EMA4015 mg／kg剂量灌胃；中剂量组，按照EMA40110 mg／kg剂量灌胃；高剂量组，按照EMA40120 mg／kg剂量灌胃。另设假手术组，给予等体积生理盐水灌胃。各组于术前、术后7 d、14 d和28 d同一时间测定热缩足反射潜伏期（ thermal withdrawal latency，TWL）和机械缩足阈值（ mechanical withdrawal threshold ，MWT）行为学指标。行为学检测完毕后，各组大鼠取腰段DRG，采用邻甲酚酞络合铜微板法检测DRG内Ca2＋浓度，采用Western blotting 和RT－PCR分析检测DRG内GAP－43、PKC和CaM蛋白和mRNA的相对表达量。结果：与model组比较，EMA401显著升高CCI大鼠TWL和MWT（ P＜0．05）；与model组比较，EMA401显著降低DRG内Ca2＋浓度及GAP－43、PKC、CaM蛋白和mRNA的相对表达量（ P＜0．05）。结论：EMA401对CCI大鼠具有明显的镇痛效应，其机制可能与抑制DRG内Ca2＋浓度及GAP－43、PKC、CaM表达有关。%AIM:To explore whether angiotensin Ⅱtype 2 receptor antagonist EMA 401 decreases neuropathic pain and the expression of growth-associated protein-43 (GAP-43), protein kinase C (PKC) and calmodulin (CaM) in dorsal root ganglia (DRG) during chronic constriction injury (CCI) in rats.METHODS:SD rats were used to establish CCI model and randomly divided into 4 groups.The rats in model group were given equal volume of normal saline by intra-gastric administration .The rats in low dose ( LD) group were given 5 mg/kg EMA401 by intragastric administration .The rats in middle dose ( MD) group were given 10 mg/kg EMA401 by intragastric administration .The rats high dose ( HD) group were given 20 mg/kg EMA401 by intragastric administration .The rats in sham operation group received equal volume of normal saline by intragastric administration .Thermal withdrawal latency ( TWL ) and mechanical withdrawal threshold (MWT) were measured before operation and 7 d, 14 d and 28 d after CCI.After behavioral test, DRG of lumbar spinal was obtained from each group , and was used to determine Ca 2+concentration by o-cresolphthalein complexone microplating method, and the expression of GAP-43, PKC and CaM at mRNA and protein levels by Western blotting and RT-PCR.RE-SULTS:Compared with model group, EMA401 significantly increased the TWL and MWT (P <0.05).Meanwhile, EMA401 significantly reduced Ca 2+concentration and the expression of GAP-43, PKC and CaM at mRNA and protein levels in the DRG (P<0.05).CONCLUSION:EMA401 may attenuate neuropathic pain of CCI by inhibiting Ca 2+concentra-tion and the expression of GAP-43, PKC and CaM.