α-Synuclein expression is required for somatodendritic dopamine release and immediate early gene induction.

α-Synuclein (αSyn) is a presynaptic protein of unestablished physiological function that plays a central role in Parkinson's disease neuropathology. To date, the reported effects of αSyn expression on the kinetics of axonal synaptic vesicle exocytosis and membrane cycling have been relatively small. In contrast, we report that αSyn is the major modulator of substantia nigra somatodendritic dopamine release, a little-understood form of neurotransmission that is central to sensorimotor and basal ganglia circuitry. This regulation is due to a previously unknown role for αSyn in controlling the activity of the L-type calcium ion channels (LTCC), which are also implicated in Parkinson's pathogenesis. αSyn-deficient neurons further display decreased spike frequency adaptation, hippocampal LTCC-dependent long-term potentiation, and immediate early gene induction, functions that are essential for synaptic adaptation and neuronal plasticity.