OBJECTIVETo investigate retrograde death of dorsal root ganglion sensory neurons and spinal cord motorneurons after semi or whole C7 nerve root axotomy.To detect retrograde degeneration of dorsal root ganglion sensory neuron and spinal cord motoneuron after C7 transection and neurorrhaphy at different intervals.To disclose the effect of lidocaine in preventing spinal cord motoneuron and dorsal root ganglion sensory neuron from retrograde degeneration.To investigate the relationship of neuronal protective effect and different time interval after lidocaine injection.To compare the neuronal protective effect of lidocaine, procaine and bupivacaine injection.MATERIALS AND METHODSThe capital techniques involved in all experiments were as follows: SD rat model of seventh cervical nerve root transection, True Blue retrograde tracing technique, fluorescent labeling neuron count technique and True Blue tracing—NSE immunofluorescent double labeling technique. Various parts of C7 nerve root were transected in this part of experiment. The animals were randomly divided into normal control group, whole C7 transection group, C7 anterior division transection group, and C7 posterior division transection group. The numbers of True Blue positively labeled neurons in all groups were counted at different time intervals and were statistically analyzed. C7 transection was done in this part of experiment. The rats were then randomly divided into immediate suturing group, 4 weeks delayed suturing group, 8 weeks delayed suturing group and 12 weeks delayed suturing group. The numbers of True Blue positively labeled neurons in all groups of were counted at different time intervals and were statistically analyzed.The rats were randomly divided into control group and lidocaine group. In lidocaine was intrathecally injected prior to C7 nerve transaction. The numbers of True Blue positively labeled neuron in all groups of were counted at different time intervals and were statistically analyzed.In this part, experimental animals were randomly divided into control group, lidocaine-0 minute group and lidocaine-10 minutes group. In the control group, C7 nerve root was transected without lidocaine injection. In lidocaine-0 minute group, C7 was transected immediately after lidocaine injection, while in lidocaine-10 minute group, C7 was transected 10 minutes after lidocaine injection. The numbers of True Blue positively labeled neuron in all groups were counted at different time intervals and were statistically analyzed.The rats were randomly divided into control group, lidocaine group, procaine group and bupivacaine group, representing no injection, lidocaine injection, procaine injection and bupivacaine injection respectively. The numbers of True Blue positively labeled neuron in all groups were counted at different time intervals and were statistically analyzed.RESULTSThe fluorescent dye True Blue could be kept in neuronal cytoplasmic for at least 16 weeks without noticable leakage. After 16 weeks, the sufficient fluorescent light could be detected for neuron counting. True Blue labeled neurons could be NSE immunofluorecent double dyed both after 1 weeks or 16 weeks.The counting results of dorsal root ganglion sensory neuron: Significant neuron loss was detected from 4 weeks to 16 weeks postoperatively in whole C7 nerve root transection group(P<0.05 In C7 anterior division transection group, significant neuron loss could only be detected at 4 weeks postoperatively (P<0.05)and couldn't be found later on; In C7 posterior division transection group, there was no neuron loss founded at different time intervals. The counting results of spinal cord motoneurons: Significant neuron loss was detected from 8 weeks to 16 weeks postoperatively in whole C7 transection group(P<0.05 In C7 posterior division transection group, significant neuron loss could only be detected at 8 weeks postoperatively (P<0.05)and couldn't be found later on; In anterior division transection group, there was no neuron loss detected at diff