Olfactory transduction in vertebrate olfactory receptor neurons (ORNs) involves primarily a cAMP-signaling cascade that leads to the opening of cyclic-nucleotide-gated (CNG), nonselective cation channels. The consequent Ca2+ influx triggers adaptation but also signal amplification, the latter by opening a Ca2+-activated Cl channel (ANO2) to elicit, unusually, an inward Cl current. Hence the olfactory response has inward CNG and Cl components that are in rapid succession and not easily separable. We report here success in quantitatively separating these two currents with respect to amplitude and time course over a broad range of odorant strengths. Importantly, we found that the Cl current is the predominant component throughout the olfactory dose-response relation, down to the threshold of signaling to the brain. This observation is very surprising given a recent report by others that the olfactory-signal amplification effected by the Ca2+-activated Cl current does not influence the behavioral olfactory threshold in mice.
|Number of pages||10|
|Journal||Proceedings of the National Academy of Sciences of the United States of America|
|State||Published - 4 Oct 2016|
Bibliographical noteFunding Information:
We thank Haiqing Zhao, Randall Reed, Jeremy Nathans (all of Johns Hopkins University School of Medicine), Samuel M. S. Wu (Baylor College of Medicine), and members of the K.-W.Y. laboratory for discussions and comments on the manuscript. We also thank the two reviewers for their extremely helpful comments. This work was supported by NIH Grant R01 DC14941 (to K.-W.Y.).
© 2016, National Academy of Sciences. All rights reserved.
- Calcium-activated chloride channel
- Cyclic-nucleotide-gated channel
- Olfactory receptor neurons
- Olfactory transduction
- Signal amplification