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For Immediate Release
Contact: Tonya Ewers, 303.724.1524, pager 303.266.0941, Tonya.Ewers@uchsc.edu
University of Colorado Denver Researchers Discover New Cell Function in the Nose
Specialized sensory cells cause the nose to tingle and react to irritants in the environment
AURORA, Colo. (March 4, 2008) - The nose knows but until now no one could explain the source of the tingling, itching and sneezing which occurs when exposure to irritants in the environment occurs - such reactions can be caused by slicing an onion, mowing the lawn or even pollution. A team of researchers from the Rocky Mountain Taste and Smell Center at the University of Colorado Denver School of Medicine, along with colleagues at the University of Maryland, Baltimore, and the Mount Sinai School of Medicine in New York, have discovered that truly, it is the nose that knows. The researchers discovered a large group of chemosensory cells in the nasal cavity that are responsible for reactions in the nose - such as tingling, burning, stinging, warmth, itching or pain - that occur when exposed to environmental factors. The sensory response is a defense mechanism to alert the body to the presence of chemical odors, poor air quality and thus, potential health risks.
"We've known for some time that inhaled airborne irritants trigger sensory responses in the nose," said Diego Restrepo, PhD, professor of Cell and Developmental Biology and director of the Neuroscience Program at the UC Denver School of Medicine and co-author on the study. "What is poorly understood is how the response occurs. Previously, it was thought that olfactory sensory neurons - which give us a sense of smell - detected odor and molecules in the air and in this study, we discovered a colony of specialized receptor cells in the upper nasal cavity that respond to a variety of chemical irritants."
Many chemicals, including most odorants in highly concentrated form, are irritating to the nose and can cause sensory responses. Sensations occur when high levels of the chemical odors activate the trigeminal sensory system in the nasal cavity - signaling poor air quality or environmental risk. The trigeminal nerve includes the three branches of nerve endings in the face that are responsible for sensations.
"We do not fully understand the initial steps in how the cells detect the irritants but these findings are an important step in that direction," said Thomas Finger, PhD, co-investigator and professor of Cell and Developmental Biology at the UC Denver School Medicine. "We do know these cells cause a sensory response that allows humans and animals to quickly monitor and avoid irritating or toxic compounds in the environment. More than 5,000 sensory cells were detected on each side of the nasal cavity - a large number indicating the importance of these cells in this role."
According to Dr. Lin, the first author of the study, "We have discovered a new cell function that we did not know existed. These findings bring us a step closer to understanding the way in which certain cells inside the nose protect us from potential harm."
Dr. Lin is now with the University of Maryland, Baltimore, but conducted the bulk of this research while in Colorado at the Rocky Mountain Taste and Smell Center at UC Denver's Anschutz Medical Campus.
"TRPM5-expressing Solitary Chemosensory Cells Respond to Odorous Irritants" appears in the March 2008 edition of the Journal of Neurophysiology (doi:10.1152/jn.01195.2007), a publication of the American Physiological Society (APS; http://www.the-aps.org/).
The School of Medicine faculty work to advance science and improve care as the physicians, educators and scientists at University of Colorado Hospital, The Children's Hospital, Denver Health, National Jewish Medical and Research Center, and the Denver Veterans Affairs Medical Center. Degrees offered by the UC Denver School of Medicine include doctor of medicine, doctor of physical therapy, and masters of physician assistant studies. The School is part of the University of Colorado Denver, one of three universities in the University of Colorado system. For additional news and information, please visit the UC Denver newsroom online.
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