Localized Synaptic Potentiation by BDNF Requires Local Protein Synthesis in the Developing Axon
Brain-derived neurotrophic factor (BDNF) is known to promote neuronal survival, guide axonal pathfinding, and participate in activity-dependent synaptic plasticity. In Xenopus nerve-muscle cultures, localized contact of a single BDNF-coated bead with the presynaptic axon resulted in potentiation of transmitter secretion at the developing synapses, but only when the bead was placed within 60 μm from the synapse. The localized potentiation induced by BDNF is accompanied by a persistent local elevation of [Ca2+]i in the axon and requires constitutive presynaptic protein translation, even for axons severed from the cell body. Thus, presynaptic local TrkB signaling and protein synthesis allow a localized source of BDNF to potentiate transmitter secretion from nearby synapses, a property suited for spatially restricted synaptic modification by neurotrophins.