BDNF potentiates spontaneous Ca2+ oscillations in cultured hippocampal neurons

Brain-derived neurotrophic factor (BDNF) is thought to regulate neuronal plasticity in developing and matured neurons, although the molecular mechanisms are less well characterized. We monitored changes in the intracellular calcium (Ca2+) levels induced by BDNF using a fluorescence Ca2+ indicator (Fluo-3) by means of confocal laser microscopy in rat cultured hippocampal neurons. BDNF acutely potentiated spontaneous Ca2+ oscillations in dendrites and also in the soma of several neurons, although it increased intracellular Ca2+ in only selective proportion of resting neurons without Ca2+ oscillations. The potentiation was observed both in the frequency and the amplitude of Ca2+ oscillations, completely blocked by K-252a, and significantly reduced by 2-aminophosphonovaleric acid. These findings suggest that BDNF increases glutamate release and N-methyl-D-aspartate (NMDA) channel-gated Ca2+ influx via TrkB and regulates the frequency and the amplitude of Ca2+ oscillations. BDNF may have the potential to modulate spontaneous Ca2+ oscillations to regulate neuronal plasticity in developing hippocampal neurons.