Scientists from the Monell Center report that functional olfactory
receptors, the sensors that detect odors in the nose, are also present in human
taste cells found on the tongue. The findings suggest that interactions between
the senses of smell and taste, the primary components of food flavor, may begin
on the tongue and not in the brain, as previously thought.
“Our research
may help explain how odor molecules modulate taste perception,” said study
senior author Mehmet Hakan Ozdener, MD, PhD, MPH, a cell biologist at Monell.
“This may lead to the development of odor-based taste modifiers that can help
combat the excess salt, sugar, and fat intake associated with diet-related
diseases such as obesity and diabetes.”
While many
people equate flavor with taste, the distinctive flavor of most foods and
drinks comes more from smell than it does from taste. Taste, which detects
sweet, salty, sour, bitter, and umami (savory) molecules on the tongue, evolved
as a gatekeeper to evaluate the nutrient value and potential toxicity of what
we put in our mouths. Smell provides detailed information about the quality of
food flavor, for example, is that banana, licorice, or cherry? The brain
combines input from taste, smell, and other senses to create the multi-modal
sensation of flavor.
Until now, taste
and smell were considered to be independent sensory systems that did not
interact until their respective information reached the brain. Ozdener was
prompted to challenge this belief when his 12-year-old son asked him if snakes
extend their tongues so they can smell.
In the study, published online in Chemical Senses, Ozdener and
colleagues used methods developed at Monell to maintain living human taste
cells in culture. Using genetic and biochemical methods to probe the taste cell
cultures, the researchers found that the human taste cells contain many key
molecules known to be present in olfactory receptors.
They next used a
method known as calcium imaging to show that the cultured taste cells respond
to odor molecules in a manner similar to olfactory receptor cells.
Together, the
findings provide the first demonstration of functional olfactory receptors in
human taste cells, suggesting that olfactory receptors may play a role in the
taste system by interacting with taste receptor cells on the tongue. Supporting
this possibility, other experiments by the Monell scientists demonstrated that
a single taste cell can contain both taste and olfactory receptors.
“The presence of
olfactory receptors and taste receptors in the same cell will provide us with
exciting opportunities to study interactions between odor and taste stimuli on
the tongue,” said Ozdener.
In addition to
providing insight into the nature and mechanisms of smell and taste
interactions, the findings also may provide a tool to increase understanding of
how the olfactory system detects odors. Scientists still do not know what
molecules activate the vast majority of the 400 different types of functional
human olfactory receptors. Because the cultured taste cells respond to odors,
they potentially could be used as screening assays to help identify which
molecules bind to specific human olfactory receptors.
Moving forward,
the scientists will seek to determine whether olfactory receptors are
preferentially located on a specific taste cell type, for example, sweet- or
salt-detecting cells. Other studies will explore how odor molecules modify
taste cell responses and, ultimately, human taste perception.
Journal article: https://academic.oup.com/chemse/article-abstract/44/5/289/5470701?redirectedFrom=fulltext
Source: https://myfusimotors.com/2020/03/15/smelling-with-your-tongue/
No comments:
Post a Comment