title: Cyclic nucleotide-gated channel activation is not required for activity-dependent labeling of zebrafish olfactory receptor neurons by amino acids.
abstract: The olfactory epithelium of fish is heterogeneous both with respect to the types of receptor cells (ORNs) present and the families of odorant receptors expressed in these cells. As a consequence of this diversity, the transduction cascade(s) activated by odorants has yet to be unambiguously established. In the current study, electrophysiological and activity-dependent labeling techniques were used to assess the role of the cyclic nucleotide-gated channel in zebrafish olfactory transduction. Both amino acid and bile salt odorants elicited robust electrophysiological responses, however, activity-dependent labeling of ORNs could be stimulated only by the amino acid odorants. An adenylate cyclase (AC) activator (forskolin) and a phosphodiesterase inhibitor (3-isobutyl-1-methylxanthine, IBMX) also elicited robust electrophysiological responses; generally larger than the responses elicited by either the amino acid or bile salt odorants. However, neither forskolin alone or a mixture of forskolin and IBMX stimulated activity-dependent labeling. Bathing the olfactory epithelium with forskolin, which presumably increased the intracellular concentration of cAMP, reduced the responses to bile salt odorants to a significantly greater extent than amino acid odorants. Collectively, these findings suggest that the transduction of amino acid input does not rely primarily on cyclic nucleotide-gated (CNG) channel activation and that CNG channel activation may be required for the transduction of bile salt input.
authors.affiliation: University of Utah School of Medicine, Department of Physiology, Salt Lake City, UT 84108, USA.
authors.forename: W C
authors.initials: WC
authors.lastname: Michel
mesh_terms: D000376:Agmatine / Q000494:pharmacology; D000596:Amino Acids / Q000494:pharmacology*; D000818:Animals; D001647:Bile Acids and Salts / Q000494:pharmacology; D005576:Colforsin / Q000494:pharmacology; D000242:Cyclic AMP / Q000378:metabolism; D054815:Cyclic Nucleotide-Gated Cation Channels; D007425:Intracellular Membranes / Q000378:metabolism; D007473:Ion Channels / Q000502:physiology*; D009475:Neurons, Afferent / Q000187:drug effects / Q000502:physiology*; D009812:Odorants; D009833:Olfactory Pathways / Q000187:drug effects / Q000502:physiology*; D015027:Zebrafish / Q000502:physiology*
chemical_list: D000596:Amino Acids; D001647:Bile Acids and Salts; D054815:Cyclic Nucleotide-Gated Cation Channels; D007473:Ion Channels; D005576:Colforsin; D000376:Agmatine; D000242:Cyclic AMP