Substance K excites dopaminergic and non-dopaminergic neurons in rat substantia nigra

Substance K (SK) is a newly discovered neuropeptide which is a member of the tachykinin family that includes substance P (SP). As it is present in high concentrations in substantia nigra, we have investigated the electrophysiological activity of SK microiontophoresed onto single neuronal units in this region. SK microiontophoresed onto single units in the substantia nigra caused excitation of approximately 50% of both dopaminergic and non-dopaminergic neurons. This relatively high proportion of responsivity correlates with the reported high density of SK receptors in the substantia nigra.