IMPROVED NEUROCHEMICAL RECOVERY OF 6-HYDROXYDOPAMINE-LESIONED POSTGANGLIONIC SYMPATHETIC NEURONS BY NERVE GROWTH-FACTOR IN THE ADULT-RAT

Intraplantar injections of nerve growth factor (NGF; five injections o f 4 mu g each in 30 h intervals) were able to locally improve the reco very of the noradrenaline content in 6-hydroxydopamine (6-OHDA)-lesion ed sympathetic nerves in adult rats. Whereas 8 days after the 6-OHDA t reatment the noradrenaline content in the paw skin was still less than 10% of control, it reached up to 40% of control levels in NGF injecte d paws. Intraplantar NGF also significantly improved the recovery of t he noradrenaline content in the innervating sciatic nerve, but not in distant tissues. The NGF-induced recovery of noradrenergic nerves was independent of the presence of sensory peptidergic afferents and it co uld not be mimicked by a local inflammatory response known to raise en dogenous NGF production. These results show that rather low doses of e xogenous NGF were able to locally restore peripheral noradrenergic ner ves after an acute neurotoxin lesion. (C) 1996 Elsevier Science Irelan d Ltd.