Irritating and dangerous smells alert special cells at nose entry

Washington, Mar 5 (UNI) If you chop an onion you risk crying due to burning sensation that overwhelms your eyes and nose.

Researchers do not know why certain chemical odours, like onion, ammonia and paint thinner, are so highly irritating, but new findings in mice has uncovered an unexpected role for specific nasal cavity cells.

There is a particular cell which is abundant near the entry of many animal noses, plays a crucial and previously unknown role in transmitting irritating and potentially dangerous odours.

The scientists have identified the role of this solitary chemosensory cell in transmitting irritating chemical odors in the noses of mice science daily reported.

Scientists have found similar solitary chemosensory cells in the nasal cavities, airways and gastrointestinal tracts of many mammals as well as fish, frogs and alligators; they think it is likely that they are also present in humans, explains Thomas Finger, Ph.D., one of the senior co-authors at the University of Colorado Denver.

Prior to this work, scientists who study smell and taste thought that irritating odors directly stimulated the trigeminal nerve, which senses touch, temperature and pain throughout the head region, including the delicate membranes that line the inside of the nose.

The research team, under the guidance of Diego Restrepo, Ph.D., found that solitary chemosensory cells scattered in the epithelium inside the front of the nose respond to high levels of irritating odors and relay signals to trigeminal nerve fibers.

''This elegant research corrects an erroneous assumption about how irritating odors are perceived and expands our understanding of olfaction,'' says James F. Battey, M.D., Ph.D., director of NIDCD.

''With further investigation, it also might lead to a better understanding of why some people are exceptionally sensitive to irritating odors,'' he added.

The researchers say their findings raise new questions about how irritating odours are detected.

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