The BDNF secreted by immune cells is bioactive, as it supports neuronal survival in vitro.;Brain-derived neurotrophic factor (BDNF) was found to promote the survival of Ell 7 rat embryo septal cholinergic neurons in culture, as assessed by a histochemical stain for acetylcholinesterase (AChE);Thus, the survival action of NGF and BDNF against STS-induced neurotoxicity was mediated by the activation of PI3K/Akt signaling through the Trk receptor.;In explants treated for 7 days, the actions of NT-4/5 were similar to those of brain-derived neurotrophic factor (BDNF)- with either neurotrophin, nearly twice as many RGCs survived and there was a two- to threefold increase in the number of neurites formed by RGCs.