Taste cells may work together in ‘circuit’, suggests review

The study, published in Flavour and Fragrance Journal​, reviews the structural and functional diversity of taste cells in the mouth; noting that unlike other sensory cells, such as hair cells or rods in the retina, taste cells differ from each other in terms of structural features. The diverse structures and functions of taste cells found in a taste bud has led researchers to suggest a circuit-based model of taste reception and signalling.

The research may help to provide models that fully understand how tastes are detected and interpreted in the mouth.

“At least three main morphotypes ​[structurally different types] are now recognized in mammalian taste buds…Each of them displays specific membrane properties (i.e. ion channels and receptors) as well as intracellular signalling pathways,”​ explained the researchers, led by Professor Albertino Bigiani from the Università di Modena e Reggio Emilia, Italy.

The reviewers explained that this poses the question: “What is then the significance of these three cell types in the context of taste reception?”​

“Although it is not yet possible to draw any definitive conclusion, the emerging view is that functional diversity of taste cells might represent the basis for a ‘sensory processing’ circuitry designed to detect chemicals, as a whole,”​ they explained.

Taste cells​

In recent years, many laboratories have attempted to make sense of the molecular mechanisms that are essential to the ability of taste cells to detect chemicals and to communicate the relevant information to the brain.

Although this research has revealed new data on taste, many aspects of taste cell biology are still “waiting for an explanation,”​ noted Bigiani and colleagues.

One problem is that taste cells do constitute a ‘homogeneous’ population, as is the case for other sensory receptors: “Observations clearly indicate that taste cells share similar gross morphology (elongate cells with apical process), yet they differ for many structural features,”​ said the researchers.

At least three different cell morphotypes are recognized in mammalian taste buds (Types I, II, and III). Bigiani and co-workers said that differences in structural features “raise an obvious question: do taste cell morphotypes correspond to functional categories?”​

Review details​

“During the last 10 years, by using a combination of different techniques, […] major breakthroughs have been obtained for understanding the functional roles of cell morphotypes in mammalian taste buds,”​ said the authors.

Bigiani and colleagues explained that taste cells are diverse in terms of structure, expressed proteins, and functional properties.

“Functions are somehow segregated inside the taste buds, and it is possible to put forward a working model for the operation of this sensory organ,”​ they said.

“Of course, this model is not a definitive one … In particular, it is not yet clear if this model works also for the detection of the other two taste quality, sour and salty,”​ said the reviewers.

“Even if it is not yet possible to draw a definitive scheme of taste bud functioning, it is tempting to speculate that likely a basic motif of ‘sensory processing circuitry’ exists in mammalian taste buds, involving segregation of some principal functions to specific taste cells subsets,”​ they added.

Source: Flavour and Fragrance Journal​
Published online ahead of print, doi: 10.1002/ffj.2065
“Functional diversity of taste cells. A review”​
Authors: A. Bigiani, S. Prandi