Effects of exogenous alpha-synuclein on stimulated dopamine overflow in dorsal striatum.

•We examined the effects of exogenous alpha-synuclein protein on dopamine signaling.•We injected the protein into mouse brain and studied the effects using amperometry.•The effects depended on the presence of endogenous alpha-synuclein.•Dopamine release and re-uptake rate were decreased six days after injection.•Immediate effects of the injection were opposite but statistically non-significant.