Dopamine-releasing neurons in the substantia nigra pars compacta inhibit target cells in the striatum through postsynaptic activation of γ-aminobutyric acid (GABA) receptors. However, the molecular mechanisms responsible for GABAergic signaling remains unknown. This study demonstrated that dopamine-releasing substantia nigra pars compacta neurons do not produce GABA using Aldh1a1 but rely instead on Gat1-mediated uptake to obtain GABA for Vmat2-dependent vesicular release. The dataset contains data for underlying figures, which includes data for Aldh1a1 does not contribute to GABA co-release from dopamine neurons, GABAergic co-transmission from dopamine-releasing substantia nigra pars compacta neurons is abolished in Gat1fl/fl mice, GABA co-release from dopamine-releasing substantia nigra pars compacta axons requires Gat1-mediated GABA uptake, and Vmat2 is required for vesicular transport of GABA.