BDNF enhances neuronal growth and synaptic activity in hippocampal cell cultures.

Brain-derived neurotrophic factor (BDNF) (20 ng/ml) significantly enhanced the growth of the somata of GABA-immunoreactive neurones in primary cultures of hippocampal neurones from postnatal rats after only 24h. Whole-cell patch-clamp experiments showed an increase in spontaneous synaptic activity between neurones with time in culture. After 10 days in culture, 90% of neurones sampled in control cultures showed spontaneous synaptic activity, whereas in cultures treated with BDNF, 100% of neurones had synaptic inputs after only 6 days. This difference in spontaneous activity was not due to the lack of synaptic inputs as KCl-induced synaptic activity was equally effective in BDNF and control cultures. These experiments demonstrate the rapid rate at which BDNF can promote neuronal growth and also show that BDNF can promote long term synaptic activity.