Daily oscillation of odorant detection in rat olfactory epithelium
Eur J Neurosci. 2017-05-23; 45(12): 1613-1622
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Most of biological variables follow a daily rhythm. It holds true as well for
sensory capacities as two decades of research have demonstrated that the odorant
induced activity in the olfactory bulbs oscillates during the day. Olfactory
bulbs are the first central nervous system structures, which receive inputs from
the olfactory neurons located in the nose olfactory epithelium in vertebrates. So
far, data on variation in odorant detection in the olfactory epithelium
throughout the day are missing. Using electroolfactogram recordings in rats
housed under daily light and dark cycles, we found that the olfactory epithelium
responsiveness varies during the day with a maximum in the beginning of the light
phase. This fluctuation was consistent with cycling of transduction pathway gene
expression in the olfactory epithelium examined by qPCR. It was also consistent
with the levels of two transduction pathway proteins (olfactory-type G protein
and adenylyl cyclase III) examined by western blot. Daily variations were also
observed at the level of olfactory sensory neurons responses recorded by
patch-clamp. To rule out a potential effect of the feeding status of the animal,
we examined the variation in odorant response in starved animals during the day.
We observed a similar pattern to ad libidum fed animals. Taken together, our
results reveal that the olfactory epithelium sensitivity varies during the day in
part due to modulation of the very first step of odorant detection.
© 2017 Federation of European Neuroscience Societies and John Wiley & Sons Ltd.