Objective To observe the analgetic effect of recombinant adeno-accosiated virus with human preproenkephalin gene (rAAV/hPPE) on chronic constriction injury (CCI) rats in different injection ways.Methods Constructed rAAV/hPPE was injected into rats by different routes:subarachnoid cavity,tail vein and skeletal muscle.The changes in paw withdrawal mechincal threshod (PWMT) and paw withdrawal thermal latency (PWTL) were observed for 8 weeks to evaluate the hyperalgesia.Two months after injection,reverse transcriptase-polymerase chain reaction (RT-PCR) and radioimmunoassay were used to detect the expression and secretion of hPPE in rats.Results The behavior test results indicated that all three ways of injection could increase the PWMT and PWTL from 5th day to 8th week in CCI rats.RT-PCR revealed that the three ways of injection all could increase the expression of hPPE mRNA in different organs.The expression level of Leucin-enkephalin (L-EK) in spinal cord was highest in the intrathecal injection group,and that in vein and myocardium was highest in the tail vein injection group.Conclusion rAAV can transfect hPPE gene into neurons and NSCs with high efficiency.rAAV/hPPE injection can release hyperalgesia in rat CCI models. Key words: Adeno-accosiated virus; Proenkephalin; Pain