| Abstract: | Chemical synapses transmit gustatory signals from taste receptorcells to sensory afferent axons. Chemical (and electrical) synapsesalso provide a lateral pathway for cells within the taste budto communicate. Lateral synaptic pathways may represent someform of signal processing in the peripheral end organs of taste.Efferent synaptic input may also regulate sensory transductionin taste buds. To date, the synaptic neurotransmitter(s) orneuromodulator(s) released at chemical synapses in taste budshave not been identified unambiguously. This paper summarizesthe attempts that have been made over the past 40 years to identifythe neuroactive substances acting at taste bud synapses. Wereview the four traditional criteria for identifying chemicaltransmitters elsewhere in the nervous system—localization,uptake/degradation, release and physiological actions—andapply these criteria to neuroactive substances in taste buds.The most complete evidence to date implicates serotonin as aneuromodulator of taste transduction in the end organs. However,studies also suggest that adrenergic, cholinergic and peptidergicneurotransmission may be involved in taste buds. Chem. Senses21: 353–365, 1996. |
