Autoradiographic Distribution of Binding Sites for Iodinated Tachykinins in the Rat Central Nervous System

Tritiated and iodinated tachykinin peptide ligands bind to distinctly different types of sites in the CNS. Iritiated substance P (SP) and 125I-Bolton-Hunter reagent-labeled SP bind specifically to sites with higher affinity for SP and physa1aemin (PHYS) than for other tachykinins which has led to these being designated P-type sites. The biochemical regu1ation 0f these sites, their specificity, and their localization to CNS regions that are sensitive to the biological effects of SP suggest that the sites are SP receptors [see 1,2].