α-Synuclein facilitates dopamine release during burst firing of substantia nigra neuronsin vivo

α-Synuclein is expressed at high levels at presynaptic terminals, but defining its role on neurotransmission under physiologically-relevant conditions has proven elusive. We report that α-synuclein is responsible for a rapid facilitation of dopamine release during action potential bursts in vivo . This occurs in tandem with a far slower stimulus-dependent depression, appears to be independent of the presence of β- and γ-synucleins or effects on presynaptic calcium and is consistent with a role for synucleins in the enhancement of synaptic vesicle fusion and turnover. The results indicate that the presynaptic effects of α-synuclein are dependent on specific patterns of neuronal activity.