Solitary chemosensory cells on the surface of the nasal cavity are in close contact with trigeminal nerve fibers which end just below the surface. Earlier research revealed that these cells contain bitter taste receptors and that bitter substances applied to the surface of the nasal cavity trigger a trigeminal nerve response.
Intrigued, Drs. Restrepo and Finger decided to explore whether solitary chemosensory cells respond to irritating odors. Using nasal tissue from mice, the scientists measured a variety of changes in solitary chemosensory cells as they exposed the cells to low and high levels of several irritating, volatile chemical odors.
Among their observations were changes in electrical activity in the cellswhich indicates a response to an outside stimulusand changes in intracellular calcium ion concentrationwhich indicates signaling to other cells. Their measurements demonstrated that the solitary chemosensory cells responded to the odors and relayed sensory information to trigeminal nerve fibers.
Once stimulated, the trigeminal nerve will convey pain and burning sensations and can trigger protective reflexes such as gagging and coughing. The architecture of nasal tissue with solitary chemosensory cells on the surface and trigeminal nerve fibers just below allows the nose to detect a greater number of irritating odors, the scientists explain.
Fortunately, the threshold for triggering a response is high, so exposure to a small amount of an irritating chemical, as might naturally emanate from some kinds of fresh fruit, will not bring on gagging and coughing. For example, lemons conta
|Contact: Linda Joy|
NIH/National Institute on Deafness and Other Communication Disorders