RT Journal Article
SR Electronic
T1 Context-Dependent Modulation of Excitatory Synaptic Strength by Synaptically Released Zinc
JF eneuro
JO eNeuro
FD Society for Neuroscience
SP ENEURO.0011-17.2017
DO 10.1523/ENEURO.0011-17.2017
VO 4
IS 1
A1 Bopanna I. Kalappa
A1 Thanos Tzounopoulos
YR 2017
UL http://www.eneuro.org/content/4/1/ENEURO.0011-17.2017.abstract
AB Synaptically released zinc inhibits baseline excitatory neurotransmission; however, the role of this neuromodulator on short-term plasticity during different levels of synaptic activity remains largely unknown. This lack of knowledge prevents our understanding of information transfer across zinc-releasing synapses, including 50% of excitatory synapses in cortical areas. We used in vitro electrophysiology in mouse brain slices and discovered that the effects of zinc on excitatory postsynaptic current (EPSC) amplitudes are context-dependent. At lower frequencies of activity, synaptically released zinc reduces EPSC amplitudes. In contrast, at higher stimulation frequencies and vesicular release probability (Pr), zinc inhibits EPSC amplitudes during the first few stimuli but leads to enhanced steady-state EPSC amplitudes during subsequent stimuli. This paradoxical enhancement is due to zinc-dependent potentiation of synaptic facilitation via the recruitment of endocannabinoid signaling. Together, these findings demonstrate that synaptically released zinc is a modulator of excitatory short-term plasticity, which shapes information transfer among excitatory synapses.