BDNF acutely modulates synaptic transmission and calcium signalling in developing cortical neurons

Abstract

Brain-derived neurotrophic factor (BDNF), like other neurotrophins, has long-term effects on neuronal survival and differentiation; furthermore, BDNF has been reported to exert an acute potentiation of synaptic activity and are critically involved in long-term potentiation(LTP). We found that BDNF rapidly induced potentiation of synaptic activity and an increase in the intracellular Ca 2+ concentration in cultured cortical neurons. Within minutes of BDNF application to cultured cortical neurons, spontaneous firing rate was dramatically increased as was the frequency and amplitude of excitatory spontaneous postsynaptic currents (EPSCs). Fura-2 recordings showed that BDNF acutely elicited an increase in intracellular calcium concentration ([Ca 2+ ] i ). This effect was partially dependent on extracellular Ca 2+ . In calcium-free perfusion medium a substantial calcium signal remained which disappeared after loading of cortical neurons with 5 μM U-73122. BDNF-induce Ca 2+ transients were completely blocked by K252a and partially blocked by Cd 2+ . The results demonstrate that BDNF can enhance synaptic transmission and induce directly a rise in [Ca 2+ ] i that require two routes: the release of Ca 2+ from intracellular calcium stores and influx of extracellular Ca 2+ mainly through voltage-dependent Ca 2+ channels in cultured cortical neurons. Copyright © 2005 S. Karger AG.