Direct suppression by odorants of ionotropic glutamate receptors in newt retinal neurons.
Odorants are known to suppress voltage-gated channels not only in olfactory receptor cells but also in neurons of outside of the olfactory system. Here we found that odorants suppress glutamate-gated channels in newt retinal neurons using the Ca(2+) imaging technique. Bath application of 100 microM glutamate rose [Ca(2+)](i) under application of the voltage-gated Ca(2+) channel blocker. Thus, [Ca(2+)](i) rises in the neurons were most likely attributable to Ca(2+) influx via Ca(2+)-permeable glutamate-gated channels rather than voltage-gated Ca(2+) channels. A similar increase of [Ca(2+)](i) was observed by application of 100 microM NMDA and 50 microM kainate, suggesting that both NMDA and AMPA/kainate receptors were expressed in newt retinal neurons. Application of odorants, 1 mM amyl acetate and acetophenone, reversibly reduced [Ca(2+)](i) increased by glutamate, NMDA and kainate. This suggests that odorants can suppress not only voltage-gated channels but also ligand-gated channels such as NMDA and AMPA/kainate receptors.
Ohkuma
M
M
Department of Physiology, Fujita Health University, Toyoake, Aichi, Japan. m-ohkuma@fujita-hu.ac.jp
Kawai
F
F
Miyachi
E
E
D000818:Animals; D002118:Calcium / Q000378:metabolism*; D002121:Calcium Channel Blockers / Q000494:pharmacology; D009474:Neurons / Q000502:physiology; D009812:Odorants; D017470:Receptors, Glutamate / Q000378:metabolism / Q000502:physiology*; D018092:Kainic Acid Receptors / Q000378:metabolism; D016194:Receptors, N-Methyl-D-Aspartate / Q000378:metabolism; D012160:Retina / Q000378:metabolism / Q000502:physiology*; D012455:Salamandridae
D002118:Calcium; D002121:Calcium Channel Blockers; D017470:Receptors, Glutamate; D018092:Kainic Acid Receptors; D016194:Receptors, N-Methyl-D-Aspartate