Smelling carbon-dioxide can impact ageing

Specific odours that represent food are capable of altering an animal’s lifespan and physiological profile by activating a small number of highly specialised sensory neurons, says a new study.

Nematode worms and fruit flies that were robbed of their ability to smell or taste, for example, lived substantially longer. However, the specific odours and sensory receptors that control this effect on ageing were unknown.

Using molecular genetics in combination with behavioural and environmental manipulations, a collaboration between the lab of Scott Pletcher, molecular biologist at the University of Michigan (UM), and Gregg Roman has succeeded in identifying carbon dioxide (CO2) as the first well-defined odorant capable of altering physiology and affecting ageing.

Flies incapable of smelling CO2 live longer than flies with normal olfactory capabilities. They are also resistant to stress and have increased body fat.

To many insects, including fruit flies, CO2 represents an ecologically important odour cue that indicates the presence of food (e.g. rotting fruit or animal blood) or neighbours in distress (it has been implicated as a stress pheromone).

Indeed, this group of researchers previously showed that merely sensing one’s normal food source is capable of reversing the health and longevity benefits that are associated with a low calorie diet. They now establish that CO2 is responsible for this effect.

“We are working hard to understand how sensory perception affects health, and our new result really narrows the playing field. Somehow, these 50 or so neurons, whose primary job is to sense CO2, are capable of instigating changes that accelerate ageing throughout the organism,” says Pletcher.

Sensory perception has been shown to impact ageing in species that are separated by millions of years of evolution, suggesting that similar effects may be seen in humans, said a UM release.

“For us, it may not be the smell of yeast, for example, or the sensing of CO2 that affects how long we live, but it may be the perception of food or danger,” says Pletcher.

These findings were published in the open-access PLoS Biology