Neurokinin Receptors in Human Brain

The existence of multiple tachykinin receptors is supported by experimental evidence [for recent reviews, 1–4]. For example, substance P (SP) substance K/neurokinin A (NKA), eledoisin (ELE) and neurokinin B (NKB) induce differential effects in bioassays and their respective binding sites are differentially distributed in central and peripheral tissues [1–4]. Thus, the existence of three classes of neurokinin receptors has been proposed [5,6]. The first type preferentially binds SP while the other two demonstrate more affinities for NKA, and ELE and NKB, respectively. However, the presence of these three classes of sites has not been investigated in human brain. We report here on the characterization and autoradiographic distribution of SP, NKA and ELE/NKB binding sites in human brain.