Evidence for Cardiovascular Roles of Tachykinin Peptides in the Brain of the Rat

Abstract

In addition to substance P (SP), 4 other tachykinin peptides have so far been isolated from the mammalian nervous system, namely neurokinin A (NKA), neuropeptide K (NPK), neuropeptide γ (NPγ) and neurokinin B (NKB) (Maggio, 1988; Krause et al., 1989). These tachykinin peptides have a variety of pharmacological effects, indicating smooth muscle contraction, salivation, endothelium-dependent vasodilator actions, and depolarization of central neurons (Erspamer, 1981; Pernow, 1983). These peptides are extensively distributed and play important physiological roles in the mammalian central nervous system (CNS). Several lines of evidence have proposed the existence of multiple tachykinin receptor subtypes in peripheral tissues and the CNS, called NK-1, NK-2 and NK-3 (TABLE I). SP, NKA and NKB are considered to be endogenous ligands of the NK-1, NK-2 and NK-3 subtypes, respectively (Henry, 1987).