What do you know about olfactory receptors and smelling with your tongue?

What do you know about olfactory receptors and smelling with your tongue?
© iStock/utkamandarinka

Smelling with your tongue may be a real thing, but can identification of functional olfactory receptors in human taste cells open doors to new approaches to modify food flavour?

According to scientists from the Monell Center, USA, functional olfactory receptors, the sensors that detect odours 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 flavour, may begin on the tongue and not in the brain, as previously thought.

Can odour molecules modulate taste perception?

“Our research may help explain how odour molecules modulate taste perception,” said study senior author Mehmet Hakan Ozdener, a cell biologist at Monell. “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.”

While many people equate flavour with taste, the distinctive flavour of most foods and drinks comes more from smell than it does from taste.

Taste, which detects sweet, salty, sour, bitter, and umami (savoury) molecules on the tongue, evolved as a gatekeeper to evaluate the nutrient value and potential toxicity of what we put in our mouths. The brain combines input from 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.

Details of the study

Published in Chemical Senses, the researchers 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 odour molecules in a manner similar to olfactory receptor cells.

Combined, 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.

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

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