Open AccesscAMP-independent olfactory transduction of amino acids in Xenopus laevis tadpoles
Author(s) -
Ivan Manzini,
Detlev Schild
Publication year - 2003
Publication title -
journal of physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.802
H-Index - 240
eISSN - 1469-7793
pISSN - 0022-3751
DOI - 10.1113/jphysiol.2003.043059
Subject(s) - xenopus , olfactory receptor , olfactory bulb , transduction (biophysics) , forskolin , olfactory epithelium , biology , second messenger system , amino acid , microbiology and biotechnology , medicine , signal transduction , endocrinology , olfactory system , stimulation , biochemistry , neuroscience , central nervous system , gene
Whether odorants are transduced by only one or more than one second messenger has been a long-standing question in olfactory research. In a previous study we started to address this question mainly by using calcium imaging in the olfactory bulb. Here, we present direct evidence for our earlier conclusions using the calcium imaging technique in the mucosa slice. The above question can now unambiguously be answered. We show that some olfactory receptor neurons (ORNs) respond to stimulation with amino acids with an increase of the intracellular calcium concentration [Ca2+]i. In order to see whether or not these responses were mediated by the cAMP transduction pathway we applied forskolin or the membrane-permeant cAMP analogue pCPT-cAMP to the olfactory epithelium. The ensemble of ORNs that was activated by amino acids markedly differed from the ensemble of neurons activated by forskolin or pCPT-cAMP. Less than 6 % of the responding ORNs showed a response to both amino acids and the pharmacological agents activating the cAMP transduction pathway. We conclude that ORNs of Xenopus laevis tadpoles have both cAMP-dependent and cAMP-independent olfactory transduction pathways and that most amino acids are transduced in a cAMP-independent way.