The autoradiographic distribution of kassinin and substance K binding sites is different from the distribution of substance P binding sites in rat brain.

In the present report we have used autoradiographic receptor binding techniques to compare the distribution of substance K (SK), kassinin (K) and substance P (SP) binding sites in the rat brain. Whereas the distribution of K and SK binding sites appeared to be identical, notable differences are apparent when comparing these binding sites to the distribution of SP binding sites. These results demonstrate that in many areas of the rat brain K and SK binding sites have a different distribution than SP binding sites. These results further suggest that different classes of mammalian tachykinins may each have their own set of receptors.