Taste buds as peripheral chemosensory processors

Abstract

Taste buds are peripheral chemosensory organs situated in the oral cavity. Each taste bud consists of a community of 50–100 cells that interact synaptically during gustatory stimulation. At least three distinct cell types are found in mammalian taste buds – Type I cells, Receptor (Type II) cells, and Presynaptic (Type III) cells. Type I cells appear to be glial-like cells. Receptor cells express G protein-coupled taste receptors for sweet, bitter, or umami compounds. Presynaptic cells transduce acid stimuli (sour taste). Cells that sense salt (NaCl) taste have not yet been confidently identified in terms of these cell types. During gustatory stimulation, taste bud cells secrete synaptic, autocrine, and paracrine transmitters. These transmitters include ATP, acetylcholine (ACh), serotonin (5-HT), norepinephrine (NE), and GABA. Glutamate is an efferent transmitter that stimulates Presynaptic cells to release 5-HT. This chapter discusses these transmitters, which cells release them, the postsynaptic targets for the transmitters, and how cell–cell communication shapes taste bud signaling via these transmitters.

Taste perception, associated hormonal modulation, and nutrient intake

“…[17][18][19] These cells express a plasma membranebound nucleotidase, which degrades extracellular adenosine triphosphate (ATP) and restricts neurotransmitter spread. 20,21 Regulation of the extracellular ionic environment within the taste bud seems to be a key function.…”

“…18,26 Although some evidence exists to the contrary, 27 it has been generally accepted that individual type II receptor cells only express receptors for a specific taste quality -sweet, umami, or bitter (i.e., these three classes of taste stimuli are detected by nonoverlapping populations of taste cells within the taste bud). Sweet tastants, including artificial sweeteners, bind to a heterodimer of the G protein-coupled receptors, T1R2 and T1R3.…”

“…[51][52][53][54] These cells, also termed presynaptic cells, express voltage-gated calcium channels associated with neurotransmitter release, enzymes for serotonin, and c-amino butyric acid, as well as uptake transporters for biogenic amines. 18 In addition to their neuronal actions, type III cells also respond to sour taste and carbonation. [55][56][57][58] Interestingly, data from functional magnetic resonance imaging in humans suggest carbonation attenuates brain activity in gustatory brain regions, thus reducing sweetness perception.…”

Taste of Milk from Inflamed Breasts of Breastfeeding Mothers with Mastitis Evaluated Using a Taste Sensor

“…12 Saltiness is primarily produced by sodium ions, but other alkali metal ions also taste weakly salty. Sourness is produced by acids containing protons (H + ).…”

“…Taste sensations are produced when chemicals in foodstuffs react with membrane receptors on taste buds, and at least five basic tastes, including sourness, saltiness, sweetness, bitterness, and umami are associated with taste sensation. 12 However, because an abundance of factors is associated with the taste of foodstuffs, detection of specific factors is almost impossible. However, a taste-sensing system based on a unique concept has been developed.…”