title: Olfactory receptor antagonism between odorants.
abstract: The detection of thousands of volatile odorants is mediated by several hundreds of different G protein-coupled olfactory receptors (ORs). The main strategy in encoding odorant identities is a combinatorial receptor code scheme in that different odorants are recognized by different sets of ORs. Despite increasing information on agonist-OR combinations, little is known about the antagonism of ORs in the mammalian olfactory system. Here we show that odorants inhibit odorant responses of OR(s), evidence of antagonism between odorants at the receptor level. The antagonism was demonstrated in a heterologous OR-expression system and in single olfactory neurons that expressed a given OR, and was also visualized at the level of the olfactory epithelium. Dual functions of odorants as an agonist and an antagonist to ORs indicate a new aspect in the receptor code determination for odorant mixtures that often give rise to novel perceptual qualities that are not present in each component. The current study also provides insight into strategies to modulate perceived odorant quality.
authors.affiliation: Department of Integrated Biosciences, The University of Tokyo, Chiba, Japan.
authors.forename: Yuki
authors.initials: Y
authors.lastname: Oka
authors.forename: Masayo
authors.initials: M
authors.lastname: Omura
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Kataoka
authors.forename: Kazushige
authors.initials: K
authors.lastname: Touhara
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D000840:Anisoles / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism; D002460:Cell Line; D004305:Dose-Response Relationship, Drug; D004594:Electrophysiology; D005054:Eugenol / Q000494:pharmacology; D005456:Fluorescent Dyes; D006801:Humans; D007545:Isoproterenol; D051379:Mice; D008807:Mice, Inbred BALB C; D008954:Models, Biological; D009812:Odorants; D009831:Olfactory Mucosa / Q000166:cytology; D018034:Olfactory Receptor Neurons / Q000737:chemistry / Q000166:cytology / Q000378:metabolism; D018035:Receptors, Odorant / Q000037:antagonists & inhibitors* / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012451:Safrole / Q000494:pharmacology; D012903:Smell / Q000502:physiology*; D013329:Structure-Activity Relationship
chemical_list: D000840:Anisoles; D005456:Fluorescent Dyes; D018035:Receptors, Odorant; D005054:Eugenol; C031050:isomethyleugenol; D007545:Isoproterenol; D012451:Safrole; D002118:Calcium; C015959:isosafrole