title: Highly selective agonists for substance P receptor subtypes.
abstract: The existence of a third tachykinin receptor (SP-N) in the mammalian nervous system was demonstrated by development of highly selective agonists. Systematic N-methylation of individual peptide bonds in the C-terminal hexapeptide of substance P gave rise to agonists which specifically act on different receptor subtypes. The most selective analog of this series, succinyl-[Asp6,Me-Phe8]SP6-11, elicits half-maximal contraction of the guinea pig ileum through the neuronal SP-N receptor at a concentration of 0.5 nM. At least 60,000-fold higher concentrations of this peptide are required to stimulate the other two tachykinin receptors (SP-P and SP-E). The action of selective SP-N agonists in the guinea pig ileum is antagonized by opioid peptides, suggesting a functional counteraction between opiate and SP-N receptors. These results indicate that the tachykinin receptors are distinct entities which may mediate different physiological functions.
mesh_terms: D000109:Acetylcholine / Q000378:metabolism; D000818:Animals; D001285:Atropine / Q000494:pharmacology; D006168:Guinea Pigs; D007082:Ileum / Q000187:drug effects / Q000502:physiology; D066298:In Vitro Techniques; D009119:Muscle Contraction / Q000187:drug effects; D009130:Muscle, Smooth / Q000187:drug effects / Q000502:physiology; D009419:Nerve Tissue Proteins / Q000494:pharmacology; D009479:Neuropeptides / Q000494:pharmacology; D018040:Receptors, Neurokinin-1; D017981:Receptors, Neurotransmitter / Q000378:metabolism*; D018039:Receptors, Tachykinin; D013373:Substance P / Q000031:analogs & derivatives / Q000378:metabolism* / Q000494:pharmacology*; D015320:Tachykinins
chemical_list: D009419:Nerve Tissue Proteins; D009479:Neuropeptides; D018040:Receptors, Neurokinin-1; D017981:Receptors, Neurotransmitter; D018039:Receptors, Tachykinin; D015320:Tachykinins; D013373:Substance P; D001285:Atropine; D000109:Acetylcholine