NERVE GROWTH-FACTOR CONTRIBUTES TO THE GENERATION OF INFLAMMATORY SENSORY HYPERSENSITIVITY

Experimental inflammation produced by an intraplantar injection of com plete Freund's adjuvant results in local sensory hypersensitivity and up-regulates the neuropeptides substance P and calcitonin gene related peptide in the primary sensory neurons innervating the inflamed tissu e. The inflammation also elevates nerve growth factor levels in the sk in. Systemic administration of anti-NGF neutralizing antibodies preven t the behavioral sensitivity, the up-regulation of neuropeptides and t he inflammation-induced expression of the immediate early gene c-fos i n dorsal horn neurons, without modifying swelling and erythema. Elevat ion of the neurotrophin NGP in the periphery is a major contributor, t herefore, of inflammatory pain.