NGF INVOLVEMENT IN PAIN INDUCED BY CHRONIC CONSTRICTION INJURY OF THERAT SCIATIC-NERVE

CHRONIC constriction injury (CCI) of the rat sciatic nerve, which with in 3 days induces thermal and mechanical hyperalgesia and mechanical a llodynia, is used as a model for pain resulting from nerve injury. Inv olvement of nerve growth factor (NGF) in the development of this hyper algesia is suggested by the increase in the level of mRNA encoding NGF in cells in the injured area and in dorsal root ganglia at the level of the lesion and the greatly increased NGF levels (determined by ELIS A) in the ganglia ipsilateral to the CCI. Application of antiserum to NGF at the site of CCI delayed the appearance of hyperalgesia, whereas pre-immune serum appeared to enhance it. These results are consistent with the view that NGF is an important factor in the appearance of hy peralgesia associated with unilateral mononeuropathy.