坐骨神经损伤及神经生长因子对背根神经节中TrkA及其mRNA表达的调控

目的 研究周围神经损伤、神经再生及外源性神经生长因子对脊神经背根神经节中TrkA及TrkA mRNA表达的影响。方法 将24只SD大鼠坐骨神经从神经中段切断后，外膜缝合修复神经。实验组动物的胫后肌内每日注射NGF200U，术后3、7、14、28d，采用免疫组织化学及原位杂交方法，检查大鼠坐骨神经损伤、神经再生及外源性NGF靶肌肉注射后脊神经背根神经节中TrkA及TrkA mRNA表达。结果 正常背根神经节中有大量的神经元表达TrkA及TrkA mRNA；坐骨神经损伤后，背根神经节中TrkA的表达下降，术后7d组最低，28d接近正常；NGF靶肌肉注射后，背根神经节中TrkA的表达明显增高。结论 神经损伤后背根神经节中TrkA的表达降低，靶肌肉注射外源性NGF背根神经节中TrkA的表达增加，表明靶肌肉注射可作为NGF的有效给药途径.

The modulation on the expression of TrkA and trkA mRNA in rat dorsal root ganglion following sciatic nerve injury and exogenous NGF injection

Objective To determine the effect of peripheral nerve injury,regeneration and ex- ogernous NGF on the experission of TrkA and its mRNA in rat dorsal root ganglion (DRG).Methods The expression of TrkA and trkA mRNA was detected in rats DRG by immunohistochemistry and in situ hybridization immunohistochemistry after sciatic nerve injury,regeneration and injection of exogenous NGF into the target muscle 3,7,14 and 28 days after the operation.Results Many neurons in the nor- mal DRG showed TrkA and trkA mRNA positive immunoreactivity.The expression of TrkA and trkA mRNA was decreased after the injury and reached its lowest level at 7th day,and gradually returned dur- ing the regeration.The expression of TrkA in DRG was incresead remarkably when the exogenous NGF was injected into the target muscle.Conclusion The expression of TrkA can be down- regulated by nerve injury and ud-regulated by exogenous NGF injection,suggesting that injection of NGF into target muscle is a useful route for clinic administration.