Here’s something I never knew: odors can regulate lifespan. Well, in fruit flies, anyway – a group at Baylor published results in 2007 showing that exposure to food-derived odors (yeast smells, in the case of Drosophila) partially cancels out the longevity-inducing effects of caloric restriction. Normally fed flies showed no effect.
That 2007 paper identified a specific sensory receptor (Or83b) as modulating the effect of odor on lifespan. Now comes a report that another receptor has been tracked down in this case, the G-protein coupled Gr63a. Flies missing this particular olfactory GPCR no longer show the lifespan sensitivity to yeast odors. This narrows things down. Or83b mutations seem to broadly affect sensory response in flies, but this is a much more specific receptor, just one of a great many similar ones:
“Unlike previous reports involving more general olfactory manipulations, extended longevity via loss of Gr63a occurs through a mechanism that is likely independent of dietary restriction. We do, however, find that Gr63a is required for odorants from live yeast to affect longevity, suggesting that with respect to lifespan, CO2 is an active component of this complex odor. Because Gr63a is expressed in a highly specific population of CO2-sensing neurons (the ab1C neurons) that innervate a single glomerulus in the antennal lobe (the V glomerulus), these data implicate a specific sensory cue and its associated neurosensory circuit as having the ability to modulate fly lifespan and alter organismal stress response and physiology. Our results set the stage for the dissection of more complex neurosensory and neuroendocrine circuits that modulate aging in Drosophila. . .”
It’s going to be very interesting to follow that neuronal pathway – I’ve no idea where it will lead, but we’re bound to learn something worthwhile. To make a wild generalization straight up to humans, this makes me wonder about people who are practicing caloric restriction on themselves – they’re still exposed to food odors all the time, right? Does the same reversal apply? For me, I think that the scent of barbecue and fried catfish might be enough to do it right there, but keep in mind that I’m from Arkansas. Your mileage may vary.