Brain-derived neurotrophic factor stimulates survival and neuronal differentiation in cultured avian neural crest

The response of trunk neural crest cells taken from precise levels of the neural axis and cultured together with adjacent somites to Brain-derived neurotrophic factor (BDNF), was examined in cultures grown in a chemically defined medium. In control cultures, the number of neural crest-derived neurons expressing the HNK-1 epitope, increased as a function of somitic level in a caudorostral direction. Treatment of cultures with increasing concentrations of BDNF (50 pg/ml to 1 ng/ml) resulted in a 1.5- to 6-fold stimulation in the number of neurons developing from crest cells excised at advanced and post-migratory stages, whereas early migrating crest cells were responsive only to concentrations equal to or higher than 1 ng/ml of BDNF. Nerve growth factor used at 5 and 30 ng/ml had no effect on survival of HNK-1-positive cells at any of the somitic levels tested. In an attempt to identify the subpopulation of HNK-1-immunoreactive neurons responding to BDNF, control and treated cultures were stained for the HNK-1 antibody in combination with substance P (SP) antibodies (as a marker for sensory neurons). SP immunoreactivity localized to a subpopulation of phase-bright, HNK-1-positive neurons. The absolute number of SP-positive neurons increased 2- to 4-fold upon BDNF treatment; however, their relative proportion within the population expressing the HNK-1 epitope remained essentially unchanged from control to treated cultures (on day 1, 20% as compared to 23.3% and on day 2, 44.6% compared to 49.7% for control and treated cultures, respectively). Taken together, these data suggest that BDNF stimulates primary neuronal differentiation of SP expressing neurons, and/or their survival.