Detection of near-atmospheric concentrations of CO2 by an olfactory subsystem in the mouse.
Carbon dioxide (CO2) is an important environmental cue for many organisms but is odorless to humans. It remains unclear whether the mammalian olfactory system can detect CO2 at concentrations around the average atmospheric level (0.038%). We demonstrated the expression of carbonic anhydrase type II (CAII), an enzyme that catabolizes CO2, in a subset of mouse olfactory neurons that express guanylyl cyclase D (GC-D+ neurons) and project axons to necklace glomeruli in the olfactory bulb. Exposure to CO2 activated these GC-D+ neurons, and exposure of a mouse to CO2 activated bulbar neurons associated with necklace glomeruli. Behavioral tests revealed CO2 detection thresholds of approximately 0.066%, and this sensitive CO2 detection required CAII activity. We conclude that mice detect CO2 at near-atmospheric concentrations through the olfactory subsystem of GC-D+ neurons.
Hu
Ji
J
National Institute of Biological Sciences, Beijing, 102206, China.
Zhong
Chun
C
Ding
Cheng
C
Chi
Qiuyi
Q
Walz
Andreas
A
Mombaerts
Peter
P
Matsunami
Hiroaki
H
Luo
Minmin
M
D000818:Animals; D002245:Carbon Dioxide / Q000008:administration & dosage / Q000032:analysis* / Q000378:metabolism; D024402:Carbonic Anhydrase II / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D006152:Cyclic GMP / Q000378:metabolism; D054678:Cyclic Nucleotide Phosphodiesterases, Type 2; D054815:Cyclic Nucleotide-Gated Cation Channels; D020869:Gene Expression Profiling; D006162:Guanylate Cyclase / Q000378:metabolism; D007473:Ion Channels / Q000235:genetics / Q000378:metabolism; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D009154:Mutation; D009474:Neurons / Q000502:physiology*; D009812:Odorants; D009830:Olfactory Bulb / Q000166:cytology / Q000201:enzymology / Q000502:physiology*; D009831:Olfactory Mucosa / Q000166:cytology / Q000201:enzymology; D018034:Olfactory Receptor Neurons / Q000201:enzymology / Q000502:physiology*; D010727:Phosphoric Diester Hydrolases / Q000378:metabolism
C518240:Cnga2 protein, mouse; D054815:Cyclic Nucleotide-Gated Cation Channels; D007473:Ion Channels; D002245:Carbon Dioxide; D010727:Phosphoric Diester Hydrolases; D054678:Cyclic Nucleotide Phosphodiesterases, Type 2; C517277:Pde2a protein, mouse; D024402:Carbonic Anhydrase II; D006162:Guanylate Cyclase; D006152:Cyclic GMP