Abstract: Objective To observe the behavioral and the histopathology changes and expression of NR2B subunit in spinal dorsal horn in chronic constriction injury (CCI) rats after pulsed radiofrequency (PRF). Methods Forty-eight adult Sprague-Dawley rats were randomly divided into Sham-Sham (SS), Sham-PRF (SP), CCI-Sham (CS) and CCI-PRF (CP) groups. The right sciatic nerves (SNs) of the CS and CP groups were ligated to create the CCI model. For the SS and SP groups, the right SNs were separated without ligation. The CP and SP groups accepted PRF at the ligation site 15 days after modeling, while the electrode was placed in rats in the SS and CS groups without electricity. The hindpaw withdrawal threshold (HWT) was measured before and 3, 7, 11, 15 days after modeling, and 1, 3, 7, 11, 15 days after treatment. The right SNs at ligation sites were assessed with optical microscopic score 15 days after treatment, and the NR2B expression in the L4- 6 spinal dorsal horn were determined with Western blotting. Results HWT was significantly shorter in the CS and CP groups than in the SS and SP groups after modeling, and was more in the CP group than in the CS group. Under the optical microscope, the axonal diameter and myelin sheath thickness increased in the CP group compared to those in the CS group (P<0.01), the NR2B expression was less in the CP group than in the CS group after treatment (F=10.769, P<0.05). Conclusion PRF may reduce hyperalgesia and repair damaged SNs in CCI-induced neuropathic pain, which may associate with inhibition of the NR2B subunit expression in spinal dorsal horn.

Key words: neuropathic pain, pulsed radiofrequency, sciatic nerves, hyperalgesia, NR2B subunit