Nose and tongue have same receptors: study

A recent study claims that sensors, called functional olfactory receptors, that detect odours in the nose are also present on the tongue. The new finding may help to modify food flavour, claim researchers.

The details were published in The Journal of Chemical Senses. "Our research may help explain how odour molecules modulate taste perception. This may lead to the development of odour-based taste modifiers that can help combat the excess salt, sugar, and fat intake associated with diet-related diseases such as obesity and diabetes," said study senior author Mehmet Hakan Ozdener,

While many people equate flavour with taste, the distinctive flavour of most foods and drinks comes more from smell than it does from the taste. Smell provides detailed information about the quality of food flavour, for example, is that banana, liquorice, or cherry? The brain combines input from the taste, smell, and other senses to create the multi-modal sensation of flavour.

Until now, taste and smell were considered to be independent sensory systems that did not interact until their respective information reached the brain. Researchers used methods to maintain living human taste cells in culture. Using genetic and biochemical methods to probe the taste cell cultures, they 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 odour molecules in a manner similar to olfactory receptor cells.

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 odour 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 odours.

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 odour molecules modify taste cell responses and, ultimately, human taste perception.