BDNF, but not NT-3, promotes long-term survival of axotomized adult rat corticospinal neurons in vivo

AXOTOMY-induced death of corticospinal neurons (CSN) is prevented by intrac otrical infusions of BDNF or NT-3 within the first week after axotomy. The present study examined whether this represents merely a delay of CSN death or whether BDNF and NT-3 can promote long-term survival of these neurons in vivo. The neurotrophins were infused for an initial period of 14 days to l esioned CSN which was followed by 28 days without treatment. BDNF was able to promote CSN survival for at least 42 days while NT-3 had no significant effect. These results suggest that initial BDNF treatment induces an endoga mous mechanism that promotes survival of axotomized CSN without further exo genous neurotrophic factor supply. These findings may be important for the design of therapeutic strategies for motoneuron disease. (C) 1999 Lippincot t Williams & Wilkins.