|NIDCD-funded Researchers Find Missing "Piece of the Pie" in
Scientists funded by the National Institute on Deafness and Other Communication
Disorders (NIDCD), one of the National Institutes of Health, are a step closer
to unraveling the mystery of taste. In a study published in the December 2, 2005,
issue of Science, researchers have pinpointed the chemical responsible for transmitting
signals from the taste buds — small sensory bumps on the tongue, throat, and
roof of the mouth — to the taste nerves leading to the brain. Today’s findings
provide scientists with a more complete picture of this complicated process,
helping advance the study of taste and taste disorders.
“People with taste disorders might not be able to enjoy the fun of eating and
are at risk for other health problems, such as poorly balanced nutrition, so
researchers are working to understand more fully how our sense of taste works,” says
James F. Battey, Jr., M.D., Ph.D., director of the NIDCD. “Until now, there has
always been a missing link between the detection of chemicals in the taste buds
and the transmission of chemical signals from the taste nerves to the brain.
Through an ingenious use of genetic engineering, these researchers have finally
been able to solve the puzzle.”
Using “knockout mice,” mice that are genetically altered to be missing one or
more key genes, the researchers were able to narrow the field of possible chemicals
to one: adenosine 5’-triphosphate, or ATP, a high-energy molecule that is also
important for helping cells in the body to function. The scientists produced
mice that are missing the genes that encode two key receptors found in taste
nerves — P2X2 and P2X3 — both of which bind to ATP. They found that the taste
nerves of mice lacking the P2X2 and P2X3 genes showed no response to taste stimulation,
although the nerves remained responsive to touch, temperature, and menthol. These
results indicate that not only are P2X2 and P2X3important in transmitting taste
signals, but the chemical that they bind to — ATP — is also important. The knockout
mice also showed much lower behavioral responses to sweeteners, monosodium glutamate,
and bitter substances. What’s more, stimulation of taste buds in a laboratory
preparation resulted in the release of ATP, which would be predicted if ATP is
involved in the transmission of signals from the taste buds to the taste nerves.
The research was conducted by a team of scientists from the Rocky Mountain Taste
and Smell Center, University of Colorado, as well as the University of Wisconsin,
Colorado State University, and the University of Minnesota.
NIDCD is a component of the National Institutes of Health, an agency of
the U.S. Department of Health and Human Services. NIDCD sponsors research and
research training on normal and disordered processes of hearing, balance, smell,
taste, voice, speech, and language.
The National Institutes of Health (NIH) — The Nation's Medical Research
Agency — includes 27 Institutes and Centers and is a component of
the U. S. Department of Health and Human Services. It is the primary Federal
agency for conducting and supporting basic, clinical, and translational medical
research, and it investigates the causes, treatments, and cures for both common
and rare diseases. For more information about NIH and its programs, visit http://www.nih.gov.