title: Olfactory transduction pathways in the Senegalese sole Solea senegalensis.
abstract: This study tested whether differences in sensitivity between the upper and lower olfactory epithelia of Solea senegalensis are associated with different odorant receptors and transduction pathways, using the electro-olfactogram. Receptor mechanisms were assessed by cross-adaptation with amino acids (L-cysteine, L-phenylalanine and 1-methyl-L-tryptophan) and bile acids (taurocholic acid and cholic acid). This suggested that relatively specific receptors exist for 1-methyl-L-tryptophan and L-phenylalanine (food-related odorants) in the lower epithelium, and for taurocholic acid (conspecific-derived odorant) in the upper. Inhibition by U73122 [a phospholipase C (PLC) inhibitor] suggested that olfactory responses to amino acids were mediated mostly, but not entirely, by PLC-mediated transduction (IC50 ; 15-55 nM), whereas bile acid responses were mediated by both PLC and adenylate cyclase-cyclic adenosine monophosphate (AC-cAMP) (using SQ-22536; an AC inhibitor). Simultaneous application of both drugs rarely inhibited responses completely, suggesting possible involvement of non-PLC and non-AC mediated mechanisms. For aromatic amino acids and bile acids, there were differences in the contribution of each transduction pathway (PLC, AC and non-PLC and non-AC) between the two epithelia. These results suggest that differences in sensitivity of the two epithelia are associated with differences in odorant receptors and transduction mechanisms.
authors.affiliation: Centro de Ciências do Mar, Universidade do Algarve, Faro, Portugal. zvelez@ualg.pt
authors.forename: Z
authors.initials: Z
authors.lastname: Velez
authors.forename: P C
authors.initials: PC
authors.lastname: Hubbard
authors.forename: E N
authors.initials: EN
authors.lastname: Barata
authors.forename: A V M
authors.initials: AV
authors.lastname: Canário
mesh_terms: D000225:Adenine / Q000031:analogs & derivatives / Q000494:pharmacology; D000067956:Adenylyl Cyclase Inhibitors; D000262:Adenylyl Cyclases / Q000378:metabolism; D000596:Amino Acids / Q000378:metabolism; D000818:Animals; D001647:Bile Acids and Salts / Q000378:metabolism; D000242:Cyclic AMP / Q000378:metabolism; D004848:Epithelium / Q000502:physiology; D004963:Estrenes / Q000494:pharmacology; D005412:Flatfishes / Q000502:physiology*; D011760:Pyrrolidinones / Q000494:pharmacology; D018035:Receptors, Odorant / Q000502:physiology*; D015398:Signal Transduction / Q000502:physiology*; D012903:Smell / Q000502:physiology*; D010738:Type C Phospholipases / Q000037:antagonists & inhibitors / Q000378:metabolism
chemical_list: D000067956:Adenylyl Cyclase Inhibitors; D000596:Amino Acids; D001647:Bile Acids and Salts; D004963:Estrenes; D011760:Pyrrolidinones; D018035:Receptors, Odorant; C060229:1-(6-((3-methoxyestra-1,3,5(10)-trien-17-yl)amino)hexyl)-1H-pyrrole-2,5-dione; C017759:9-(tetrahydro-2-furyl)-adenine; D000242:Cyclic AMP; D010738:Type C Phospholipases; D000262:Adenylyl Cyclases; D000225:Adenine
keywords: adenylate cyclase; amino acid; asymmetry; bile acid; electro-olfactogram; phospholipase C