Nerve growth factor of red nucleus involvement in pain induced by spared nerve injury of the rat sciatic nerve.

Nerve growth factor (NGF), a member of the neurotrophin family, is essential for the development and maintenance of sensory neurons and for the formation of central pain circuitry. The current study was designed to evaluate the expression of NGF in the brain of rats with spared nerve injury (SNI), using immunohistochemical technique. The results showed that the level of NGF in the Red nucleus (RN) of SNI rats was apparently higher than that of sham-operated rats. To further study the effect of NGF in the development of neuropathic pain, different doses of anti-NGF antibody (20, 2.0 and 0.2 microg/ml) were microinjected into the RN contralateral to the nerve injury side of SNI rats. The data suggested that the higher doses of anti-NGF antibody (20 and 2.0 microg/ml) significantly attenuated the mechanical allodynia of neuropathic rats, while the 0.2 microg/ml antibody showed no analgesic effect. These results suggest that the NGF of RN is involved in the development of neuropathic allodynia in SNI rats.