Do Transient Receptor Protein (TRP) Channels Play a Role in Oral Astringency?

Abstract

AbstractAstringency is the dry sensation when solutions containing polyphenols are taken into the mouth. It is believed that polyphenols interact with salivary proteins to disrupt the lubricating layer, thus causing the perceived dryness. However, some recent data have suggested that the oral epithelial cells may be directly stimulated by polyphenols by activating transient receptor protein (TRP) channels. To test this theory, TRP channels in immortalized oral epithelial cells (TR146) were incubated with TRP agonists and black tea. In addition, human oral epithelial cells were collected and stimulated. Whereas the TR146 cells responded to known TRP agonists (camphor, capsaicin and menthol), they did not respond to the tea solution. In addition, nearly all the human oral epithelial cells did not respond to either the TRP agonists or the tea solution. It is concluded that human oral epithelial cells are not directly stimulated by polyphenols during the normal drinking of black tea.Practical ApplicationsThere is an increasing awareness of the role of transient receptor protein (TRP) receptors being important for various taste modalities. Because TRP channels occur in most epithelial cells, it was important to check to see if human oral epithelial cells have functional TRP channels. It appears that the top layer of cells does not, however, some sensory nerves and some deeper epithelial cells may have functional channels. This is important for any tastant that may affect TRP channels, particularly those described as having a trigeminal effect.