Abstract
Taste buds represent a community of cells that not only collect but also analyze gustatory information via synaptic interactions. Type II (“receptor”) cells express receptors for sweet, bitter, or umami compounds. These cells secrete ATP via unconventional synapses—hemichannels likely composed of pannexin 1. ATP excites neighboring Type III cells and also may be a transmitter between Receptor cells and sensory fibers. Type III (‘presynaptic”) cells respond to sour compounds (acids) and release serotonin and norepinephrine. Serotonin inhibits adjacent receptor cells and thus exerts inhibitory feedback during taste reception. Taste buds also contain Type I (“glial”) cells that degrade/take up neurotransmitters and may be responsible for spatial buffering of K
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. The functional responses of Type I cells and their involvement in the microcircuitry of the taste bud are presently unknown. The combined actions of ATP, serotonin, norepinephrine, and asyet unidentified transmitters process and modulate taste signals during gustatory activation.