The potential role of nerve growth factor in cryoneurolysis-induced neuropathic pain in rats.

Cryoanalgesia is suggested as a risk factor of neuropathic pain. The current study investigated the pain behavior of sciatic nerve cryoneurolysis (SCN) in adult male rats. The role of nerve growth factor (NGF) was also studied. The mechanical threshold was significantly elevated in SCN group than sham-operation group within 14days after surgery. After 28days, 22 out of 39 SCN rats (56.4%) represented mechanical hyperalgesia. There were much more NGF-immunoreactive nerve cells expressed in the dorsal horn in SCN rats with hyperalgesia. The NGF protein levels of SCN rats measured by Western blot were higher than sham-operation rats, while they were significantly higher in SCN rats with hyperalgesia than those without hyperalgesia. Pain-related behavior improved after anti-NGF treatment, compared with vehicle control group. NGF is associated with SCN-induced neuropathic pain. Peripherally secreted NGF may play an important role in this mechanism.