Changes in IP3 and cytosolic Ca2+ in response to sugars and non‐sugar sweeteners in transduction of sweet taste in the rat.

Bernhardt, S J; Naim, Michael; Zehavi, Uri; Lindemann, Bernd

doi:10.1113/jphysiol.1996.sp021147

Cited by 192 publications

(148 citation statements)

References 31 publications

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“…Using fura-2-loaded taste buds, we verified that, as shown previously (Richter et al, 2004), ϳ50% of taste bud cells are depolarized by bath-applied KCl (50 mM). Also, as shown previously (Bernhardt et al, 1996), cells in isolated taste buds responded to bath-applied bitter tastants (here, 10 -100 M cycloheximide) and saccharin (2-20 mM). Parenthetically, different taste cells responded to cycloheximide, saccharin, or KCl depolarization, but we did not investigate this systematically.…”

Section: Resultssupporting

confidence: 73%

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Mouse Taste Buds Use Serotonin as a Neurotransmitter

et al. 2005

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Synapses between gustatory receptor cells and primary sensory afferent fibers transmit the output signal from taste buds to the CNS. Several transmitter candidates have been proposed for these synapses, including serotonin (5-HT), glutamate, acetylcholine, ATP, peptides, and others, but, to date, none has been unambiguously identified. We used Chinese hamster ovary cells stably expressing 5-HT 2C receptors as biodetectors to monitor 5-HT release from taste buds. When taste buds were depolarized with KCl or stimulated with bitter, sweet, or sour (acid) tastants, serotonin was released. KCl-and acid-induced 5-HT release, but not release attributable to sweet or bitter stimulation, required Ca 2ϩ influx. In contrast, 5-HT release evoked by sweet and bitter stimulation seemed to be triggered by intracellular Ca 2ϩ release. These experiments strongly implicate serotonin as a taste bud neurotransmitter and reveal unexpected transmitter release mechanisms.

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Section: Resultssupporting

confidence: 73%

“…taste cells via a signaling cascade involving phospholipase C ␤2 (PLC␤2) and IP 3 (Bernhardt et al, 1996;Spielman et al, 1996). Thus, a likely source of Ca 2ϩ for transmitter release elicited by these compounds was an intracellular store.…”

Section: Resultsmentioning

confidence: 99%

Mouse Taste Buds Use Serotonin as a Neurotransmitter

et al. 2005

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“…Finally, it has been suggested that animals cannot discriminate compounds that are detected by the same taste cells (Bernhardt et al, 1996;Adler et al, 2000;Dunipace et al, 2001). Our results contradict this suggestion.…”

Section: Functional Implicationscontrasting

confidence: 82%

Temporal Coding Mediates Discrimination of “Bitter” Taste Stimuli by an Insect

Glendinning

Davis²,

Rai³

2006

J. Neurosci.

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The mechanisms that mediate discriminative taste processing in insects are poorly understood. We asked whether temporal patterns of discharge from the peripheral taste system of an insect (Manduca sexta caterpillars; Sphingidae) contribute to the discrimination of three "bitter" taste stimuli: salicin, caffeine, and aristolochic acid. The gustatory response to these stimuli is mediated exclusively by three pairs of bitter-sensitive taste cell, which are located in the medial, lateral, and epipharyngeal sensilla. We tested for discrimination by habituating the caterpillars to salicin and then determining whether the habituation generalized to caffeine or aristolochic acid. We ran habituation-generalization tests in caterpillars with their full complement of taste sensilla (i.e., intact) and in caterpillars with ablated lateral sensilla (i.e., lat-ablated). The latter perturbation enabled us to examine discrimination in caterpillars with a modified peripheral taste profile. We found that the intact and lat-ablated caterpillars both generalized the salicin-habituation to caffeine but not aristolochic acid. Next, we determined whether this pattern of stimulus-generalization could be explained by salicin and aristolochic acid generating distinct ensemble, rate, temporal, or spatiotemporal codes. To this end, we recorded excitatory responses from the bitter-sensitive taste cells and then used these responses to formulate predictions about whether the salicin-habituation should generalize to caffeine or aristolochic acid, separately for each coding framework. We found that the pattern of stimulus generalization in both intact and latablated caterpillars could only be predicted by temporal coding. We conclude that temporal codes from the periphery can mediate discriminative taste processing.

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“…T1R2/3 activates the heterotrimeric G-protein gustducin, which uses cyclic nucleotides and inositol-1, 4, 5-trisphosphate (IP 3 ) as second messengers 20 . Ca 2+ imaging experiments in isolated taste buds of rat vallate, showed that activation of sweet taste receptors with sucrose increased cyclic adenosine monophosphate (cAMP) and Ca 2+ uptake but activation with artificial sweeteners resulted in increased IP 3 and Ca 2+ release 21 .…”

Section: Discussionmentioning

confidence: 99%

Expression and Distribution of the Sweet Taste Receptor Isoforms T1R2 and T1R3 in Human and Rat Bladders

2011

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Purpose: Artificial sweeteners have been shown to augment bladder contraction. We hypothesised that artificial sweeteners activate sweet taste receptors in the bladder; therefore, we investigated the expression of sweet taste receptors in human and rat bladders.Materials and Methods: Sections of human and rat bladder were cut from paraffin blocks and stained by immunohistochemistry for expression of T1R2 and T1R3 sweet taste receptors. Bladder homogenates were subjected to SDS-polyacrylamide electrophoresis followed by immunoblotting for expression of T1R2 and T1R3 receptors. Strips of rat bladder, with and without the urothelium, were suspended in organ baths and the contractile response to 10Hz electrical field stimulation, in the absence and presence of saccharin 10 -8 M -10 -3 M, was obtained. Responses to KCl in the absence and presence of saccharin and saccharin plus zinc were determined.Results: T1R2 and T1R3 sweet taste receptors were expressed in the urothelium of human and rat bladder. Immunostaining was evident in the plasma membrane of the three cell types of the urothelium and in particular the umbrella cells. Immunoblotting revealed bands at expected molecular weights in both human and rat bladder homogenates. Saccharin augmented rat bladder smooth muscle contraction to electrical field stimulation only when the urothelium was present in the bladder strip.Zinc blocked the enhancing effect of saccharin on responses to KCl.Conclusion: T1R2 and T1R3 sweet taste receptors are expressed in the urothelium of human and rat bladder. Activation of these receptors by artificial sweeteners may result in augmentation of bladder contraction.3

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Changes in IP3 and cytosolic Ca2+ in response to sugars and non‐sugar sweeteners in transduction of sweet taste in the rat.

Abstract: 1. The transduction pathways of sweet-sensitive cells in rat circumvallate (CV) taste buds were investigated with assays for inositol 1,4,

Cited by 192 publications

References 31 publications

Mouse Taste Buds Use Serotonin as a Neurotransmitter

Mouse Taste Buds Use Serotonin as a Neurotransmitter

Temporal Coding Mediates Discrimination of “Bitter” Taste Stimuli by an Insect

Expression and Distribution of the Sweet Taste Receptor Isoforms T1R2 and T1R3 in Human and Rat Bladders

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