TRPs in Taste and Chemesthesis

Abstract

TRP channels are expressed in taste buds, nerve fibers, and keratinocytes in the oronasal cavity. These channels play integral roles in transducing chemical stimuli, giving rise to sensations of taste, irritation, warmth, coolness, and pungency. Specifically, TRPM5 acts downstream of taste receptors in the taste transduction pathway. TRPM5 channels convert taste-evoked intracellular Ca2+ release into membrane depolarization to trigger taste transmitter secretion. PKD2L1 is expressed in acid-sensitive (sour) taste bud cells but is unlikely to be the transducer for sour taste. TRPV1 is a receptor for pungent chemical stimuli such as capsaicin and for several irritants (chemesthesis). It is controversial whether TRPV1 is present in the taste buds and plays a direct role in taste. Instead, TRPV1 is expressed in non-gustatory sensory afferent fibers and in keratinocytes of the oronasal cavity. In many sensory fibers and epithelial cells lining the oronasal cavity, TRPA1 is also co-expressed with TRPV1. As with TRPV1, TRPA1 transduces a wide variety of irritants and, in combination with TRPV1, assures that there is a broad response to noxious chemical stimuli. Other TRP channels, including TRPM8, TRPV3, and TRPV4, play less prominent roles in chemesthesis and no known role in taste, per se. The pungency of foods and beverages is likely highly influenced by the temperature at which they are consumed, their acidity, and, for beverages, their carbonation. All these factors modulate the activity of TRP channels in taste buds and in the oronasal mucosa.

Onset of a hypotensive effect following ingestion of flavan 3-ols involved in the activation of adrenergic receptors

“…A recent report showed that several components in food such as capsaicin, aryl isothiocyanate, or menthol stimulate sympathetic nerves through a transient receptor potential (TRP) in sensory nerves distributed throughout the gastrointestinal tract [54,55]. It has also been reported that a type of catechin oligomer similar to procyanidins is an agonist of TRP [56].…”

Detection of Spicy Compounds Using the Electronic Tongue

“…Menthol or mint was added to investigate how the e‐tongue differentiates between the chemesthesis stimuli of heating and cooling sensations (Roper, ). Thymol, from thyme, was added to the list as the sensations from the aromatic spice can elicit chemesthesis (Roper, ). The seven spicy compounds identified for this study are displayed in Table .…”

Taste buds: cells, signals and synapses

“…The pungency of chilli peppers, ginger, horseradish and black peppers is elicited by several unrelated compounds, including the vanilloids capsaicin and zingerone, the organosulfur compound allyl isothiocyanate, and the alkaloid piperine, respectively. These compounds are known to directly activate transient receptor potential cation channels (TRPs) — including TRPV1 and TRPA1 (REFS 222–225 ) — that are expressed in nociceptors, causing irritation and/or pain. Hence, the pungency of peppers has been assumed to represent the activation of trigeminal nociceptors in the oral epithelium, which makes pungency not a taste modality per se (for example, see REF.…”