中文摘要：

目的：观察鞘内注射P2Y12受体拮抗剂MRS2395对慢性坐骨神经结扎（chronic constriction injury,CCI）大鼠机械痛阈及脊髓背焦P2Y12受体、P2X4受体和P38MAPK表达变化的影响,探讨P2Y12受体参与神经病理性疼痛的相关机制.方法：成年SD大鼠随机分为3组（n=8）：假手术组、CCI模型vehicle组（鞘内注射0.005％DMSO生理盐水）、MRS2395处理组（CCI＋鞘内注射MRS2395 100 pmol/L）.CCI及MRS2395处理组大鼠均于鞘内置管7天之后行坐骨神经结扎,连续14天鞘内注射0.005％ DMSO生理盐水、MRS2395（100 pmol/L）,每天2次,在术前1天、术后第1、3、5、7、10、14天测定给药lh后机械缩足反射阈值（mechanical withdraw threshold,MWT）;在第7、14天处死大鼠,取脊髓背角,免疫印迹观察P2Y12受体、P2X4受体和P38 MAPK表达变化.结果：大鼠CCI术后l天即可出现机械痛敏;与假手术组相比,CCI组第1、3、5、7、10、14天MWT明显降低（P＜0.01）;与CCI组相比,MRS2395处理组术后第1,3,5,7天MWT明显升高（P＜0.01）;术后10天和14天MWT升高较缓（P＜0.05）.与假手术组相比,CCI组第7、14天背角P2X4受体、P2Y12受体和P38 MAPK表达明显上调（P＜0.05）;与CCI组相比,MRS2395处理组第7、14天P2Y12受体和P38MAPK表达上调均明显减弱（P＜ 0.05）; MRS2395处理组不影响CCI组第7天P2X4受体表达,但可以明显抑制CCI组第14天P2X4受体表达上调（P＜0.05）.各组大鼠脊髓背角P2Y12受体和P2X4受体表达之间存在正相关.结论：鞘内注射P2Y12拮抗剂MRS2211可以明显抑制CCI大鼠机械痛敏症状;而且脊髓背角P2X4受体和P38MAPK表达下调.这提示P2Y12受体拮抗剂可能通过影响脊髓背角小胶质细胞P2X4受体和P38MAPK表达,在脊髓水平发挥镇痛作用.

英文摘要：

Objective：The aim of this study is to investigate the effect of intrathecally injected selective P2Y12 receptor antagonist MRS2395 on mechanical withdraw threshold （MWT） and the expression of P2Y12 receptor,P2X4 receptor and P38MAPK in dorsal horn of rats with chronic constriction injury （CCI） of the sciatic nerve.Methods：All the SD rats were randomized into three groups （n =8）：sham group （sham operation,intrathecal normal saline）,CCI ＋ DMSO group （CCI ＋ intrathecal 0.005％ DMSO in saline）,CCI ＋ MRS2395 group （intrathecal 100 pmol/L MRS2395）.SD rats in all groups were intrathecally cathetered on 7 days before operation.For the ligated rats,MRS2395 （10 ul） or 0.005％ DMSO in saline （10 ul） were intrathecally administered twice per day for 14 days.Mechanical allodynia of the plantar surface of the hindpaw was tested on 1 day before surgery and at lh after intrathecal injection on 1,3,5,7,10 and 14 d after surgery in all rats.The expression of P2Y12 receptor,P2X4 receptor and P38MAPK in dorsal hom of the three groups rats were examined by western blot on 7 and 14 days after surgery.Results：MWT in CCI group were significantly lower than those in sham group within post-operative day （P ＜ 0.05）.Repeated intrathecal administration of MRS2395 markedly suppressed this decrease in MWT after nerve injury （P ＜ 0.01 at l,3,5,7 post-operative days; P ＜ 0.05 at 10 and 14 days）.Western blot showed that the expression of P2Y12 receptor,P2X4 receptor and P38MAPK was markedly enhanced in the ipsilateral dorsal horn on 7 days （P ＜ 0.01） and 14 days （P ＜0.01） after nerve injury.Repeated intrathecal administration of MRS2395 markedly suppressed the increased expression of P2Y12 receptor and P38MAPK on 7 days （P ＜ 0.01） and 14 days （P ＜ 0.01） after nerve injury.Intrathecal administration of MRS2395 produced no changes in the increased P2X4 receptor expression at 7 days after nerve injury.However,administration of MRS2395 significantly suppressed the i