Presynaptic BDNF Promotes Post-Synaptic Long-Term Potentiation in the Dorsal Striatum
Brain-Derived Neurotrophic Factor (BDNF) facilitates the formation of long-term potentiation (LTP) in hippocampus but whether this involves release from pre- vs. post- synaptic pools is unclear. We therefore tested if BDNF is essential for LTP in dorsal striatum, a structure in which the neurotrophin is present only in afferent terminals. Whole cell recordings were collected from medium spiny neurons in striatal slices prepared from adult mice. High frequency stimulation (HFS) of neocortical afferents produced a rapid and stable NMDA receptor-dependent potentiation. The ratio of AMPA to NMDA receptor-mediated components of the EPSPs was substantially increased after inducing potentiation, suggesting that potentiation involved post-synaptic changes. In accord with this, paired pulse response ratios, a measure of transmitter release kinetics, were reduced by elevated calcium but not by LTP. Infusion of the BDNF scavenger TrkB-Fc blocked the formation of potentiation, beginning with the second minute post-HFS, without reducing responses to HFS. These results suggest that presynaptic pools of BDNF can act within 2 minutes of HFS to support the formation of a post-synaptic form of LTP in striatum.