The localization and characterization of substance P and substance K in striatonigral neurons

Specific substance P and substance K radioimmunoassays coupled to high-performance liquid chromatography were used to characterize striatal and nigral tachykinin immunoreactivity. Using these assays, authentic substance P and substance K accounted for nearly all substance P and substance K immunoreactivity, respectively. A series of coronal knife cuts of the striatum caused parallel depletions in nigral substance P and substance K, consistent with the possible colocalization of these tachykinins in striatonigral neurons.