Expression of Amiloride-sensitive Epithelial Sodium Channels in Mouse Taste Cells after Chorda Tympani Nerve Crush

Sweet taste responses of mouse chorda tympani neurons: existence of gurmarin-sensitive and -insensitive receptor components. Inhibitory effects of gurmarin (gur) on responses to sucrose and other sweeteners of single fibers of the chorda tympani nerve in C57BL mice were examined. Of 30 single fibers that strongly responded to 0.5 M sucrose but were not or to lesser extent responsive to 0.1 M NaCl, 0.01 M HCl, and 0.02 M quinine HCl (sucrose-best fibers), 16 fibers showed large suppression of responses to sucrose and other sweeteners by lingual treatment with 4.8 μM (∼20 μg/ml) gur (suppressed to 4–52% of control: gur-sensitive fibers), whereas the remaining 14 fibers showed no such gur inhibition (77–106% of control: gur-insensitive fibers). In gur-sensitive fibers, responses to sucrose inhibited by gur recovered to ∼70% of control responses after rinsing the tongue with 15 mM β-cyclodextrin and were almost abolished by further treatment with 2% pronase. In gur-insensitive fibers, sucrose responses were not inhibited by gur, but were largely suppressed by pronase. These results suggest existence of two different receptor components for sweeteners with different susceptibilities to gur in mouse taste cells, one gur sensitive and the other gur insensitive. Taste cells possessing each component may be specifically innervated by a particular type of chorda tympani neurons.

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Synaptic reformation between salt-sensitive taste cells and axons after denervation of mouse chorda tympani nerve and recovery of behavioral discriminability between sodium and potassium salts

Neuroscience Research ◽

10.1016/s0168-0102(00)80994-3 ◽

2000 ◽

Vol 38 ◽

pp. S24

Author(s):

K Yasumatsu

Keyword(s):

Chorda Tympani ◽

Chorda Tympani Nerve ◽

Potassium Salts ◽

Taste Cells ◽

Sodium And Potassium

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Optogenetic Activation of Type III Taste Cells Modulates Taste Responses

Chemical Senses ◽

10.1093/chemse/bjaa044 ◽

2020 ◽

Vol 45 (7) ◽

pp. 533-539

Author(s):

Aurelie Vandenbeuch ◽

Courtney E Wilson ◽

Sue C Kinnamon

Keyword(s):

Light Response ◽

Sensory Nerves ◽

Taste Bud ◽

Chorda Tympani ◽

Chorda Tympani Nerve ◽

Type Iii ◽

Nonspecific Effects ◽

Taste Cells ◽

Specific Stimulation ◽

The Brain

Abstract Studies have suggested that communication between taste cells shapes the gustatory signal before transmission to the brain. To further explore the possibility of intragemmal signal modulation, we adopted an optogenetic approach to stimulate sour-sensitive (Type III) taste cells using mice expressing Cre recombinase under a specific Type III cell promoter, Pkd2l1 (polycystic kidney disease-2-like 1), crossed with mice expressing Cre-dependent channelrhodopsin (ChR2). The application of blue light onto the tongue allowed for the specific stimulation of Type III cells and circumvented the nonspecific effects of chemical stimulation. To understand whether taste modality information is preprocessed in the taste bud before transmission to the sensory nerves, we recorded chorda tympani nerve activity during light and/or chemical tastant application to the tongue. To assess intragemmal modulation, we compared nerve responses to various tastants with or without concurrent light-induced activation of the Type III cells. Our results show that light significantly decreased taste responses to sweet, bitter, salty, and acidic stimuli. On the contrary, the light response was not consistently affected by sweet or bitter stimuli, suggesting that activation of Type II cells does not affect nerve responses to stimuli that activate Type III cells.

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Acetic acid modulates spike rate and spike latency to salt in peripheral gustatory neurons of rats

Journal of Neurophysiology ◽

10.1152/jn.00114.2012 ◽

2012 ◽

Vol 108 (9) ◽

pp. 2405-2418 ◽

Cited By ~ 9

Author(s):

Joseph M. Breza ◽

Robert J. Contreras

Keyword(s):

Acetic Acid ◽

Artificial Saliva ◽

Type I ◽

Dependent Manner ◽

Chorda Tympani ◽

Gustatory System ◽

Chorda Tympani Nerve ◽

Concentration Dependent Manner ◽

Lingual Epithelium ◽

Taste Cells

Sour and salt taste interactions are not well understood in the peripheral gustatory system. Therefore, we investigated the interaction of acetic acid and NaCl on taste processing by rat chorda tympani neurons. We recorded multi-unit responses from the severed chorda tympani nerve (CT) and single-cell responses from intact narrowly tuned and broadly tuned salt-sensitive neurons in the geniculate ganglion simultaneously with stimulus-evoked summated potentials to signal when the stimulus contacted the lingual epithelium. Artificial saliva served as the rinse and solvent for all stimuli [0.3 M NH4Cl, 0.5 M sucrose, 0.1 M NaCl, 0.01 M citric acid, 0.02 M quinine hydrochloride (QHCl), 0.1 M KCl, 0.003–0.1 M acetic acid, and 0.003–0.1 M acetic acid mixed with 0.1 M NaCl]. We used benzamil to assess NaCl responses mediated by the epithelial sodium channel (ENaC). The CT nerve responses to acetic acid/NaCl mixtures were less than those predicted by summing the component responses. Single-unit analyses revealed that acetic acid activated acid-generalist neurons exclusively in a concentration-dependent manner: increasing acid concentration increased response frequency and decreased response latency in a parallel fashion. Acetic acid suppressed NaCl responses in ENaC-dependent NaCl-specialist neurons, whereas acetic acid-NaCl mixtures were additive in acid-generalist neurons. These data suggest that acetic acid attenuates sodium responses in ENaC-expressing-taste cells in contact with NaCl-specialist neurons, whereas acetic acid-NaCl mixtures activate distinct receptor/cellular mechanisms on taste cells in contact with acid-generalist neurons. We speculate that NaCl-specialist neurons are in contact with type I cells, whereas acid-generalist neurons are in contact with type III cells in fungiform taste buds.

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Effects of voltage perturbation of the lingual receptive field on chorda tympani responses to Na+ and K+ salts in the rat: implications for gustatory transduction.

The Journal of General Physiology ◽

10.1085/jgp.104.5.885 ◽

1994 ◽

Vol 104 (5) ◽

pp. 885-907 ◽

Cited By ~ 58

Author(s):

Q Ye ◽

G L Heck ◽

J A DeSimone

Keyword(s):

Receptive Field ◽

Voltage Clamp ◽

Maximal Response ◽

Chorda Tympani ◽

Chorda Tympani Nerve ◽

Salt Taste ◽

Negative Voltage ◽

Voltage Clamp Condition ◽

Taste Cells ◽

Clamp Condition

Taste sensory responses from the chorda tympani nerve of the rat were recorded with the lingual receptive field under current or voltage clamp. Consistent with previous results (Ye, Q., G. L. Heck, and J. A. DeSimone. 1993. Journal of Neurophysiology. 70:167-178), responses to NaCl were highly sensitive to lingual voltage clamp condition. This can be attributed to changes in the electrochemical driving force for Na+ ions through apical membrane transducer channels in taste cells. In contrast, responses to KCl over the concentration range 50-500 mM were insensitive to the voltage clamp condition of the receptive field. These results indicate the absence of K+ conductances comparable to those for Na+ in the apical membranes of taste cells. This was supported by the strong anion dependence of K salt responses. At zero current clamp, the potassium gluconate (KGlu) threshold was > 250 mM, and onset kinetics were slow (12 s to reach half-maximal response). Faster onset kinetics and larger responses to KGlu occurred at negative voltage clamp (-50 mV). This indicates that when K+ ion is transported as a current, and thereby uncoupled from gluconate mobility, its rate of delivery to the K+ taste transducer increases. Analysis of conductances shows that the paracellular pathway in the lingual epithelium is 28 times more permeable to KCl than to KGlu. Responses to KGlu under negative voltage clamp were not affected by agents that are K+ channel blockers in other systems. The results indicate that K salt taste transduction is under paracellular diffusion control, which limits chemoreception efficiency. We conclude that rat K salt taste occurs by means of a subtight junctional transducer for K+ ions with access limited by anion mobility. The data suggest that this transducer is not cation selective which also accounts for the voltage and amiloride insensitive part of the response to NaCl.

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Recovery of two independent sweet taste systems during regeneration of the mouse chorda tympani nerve after nerve crush

European Journal of Neuroscience ◽

10.1111/j.1460-9568.2007.05761.x ◽

2007 ◽

Vol 26 (6) ◽

pp. 1521-1529 ◽

Cited By ~ 13

Author(s):

Keiko Yasumatsu ◽

Yoko Kusuhara ◽

Noriatsu Shigemura ◽

Yuzo Ninomiya

Keyword(s):

Sweet Taste ◽

Chorda Tympani ◽

Chorda Tympani Nerve ◽

Nerve Crush

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Anion modulation of taste responses in sodium-sensitive neurons of the hamster chorda tympani nerve.

The Journal of General Physiology ◽

10.1085/jgp.101.3.453 ◽

1993 ◽

Vol 101 (3) ◽

pp. 453-465 ◽

Cited By ~ 38

Author(s):

B G Rehnberg ◽

B I MacKinnon ◽

T P Hettinger ◽

M E Frank

Keyword(s):

Nerve Fibers ◽

Na Channel ◽

Acetate Anion ◽

Chorda Tympani ◽

Chorda Tympani Nerve ◽

Wide Range ◽

Nacl Concentration ◽

Stimulus Concentration ◽

Taste Cells ◽

Epithelial Membranes

Beidler's work in the 1950s showed that anions can strongly influence gustatory responses to sodium salts. We have demonstrated "anion inhibition" in the hamster by showing that the chorda tympani nerve responds more strongly to NaCl than to Na acetate over a wide range of concentrations. Iontophoretic presentation of Cl- and acetate to the anterior tongue elicited no response in the chorda tympani, suggesting that these anions are not directly stimulatory. Drugs (0.01, 1.0, and 100 microM anthracene-9-carboxylate, diphenylamine-2-carboxylate, 4-acetamido-4'-isothiocyanatostilbene-2,2'-disulfonate, and furosemide) that interfere with movements of Cl- across epithelial cells were ineffective in altering chorda tympani responses to 0.03 M of either NaCl or Na acetate. Anion inhibition related to movements of anions across epithelial membranes therefore seems unlikely. The chorda tympani contains a population of nerve fibers highly selective for Na+ (N fibers) and another population sensitive to Na+ as well as other salts and acids (H fibers). We found that N fibers respond similarly to NaCl and Na acetate, with spiking activity increasing with increasing stimulus concentration (0.01-1.0 M). H fibers, however, respond more strongly to NaCl than to Na acetate. Furthermore, H fibers increase spiking with increases in NaCl concentration, but generally decrease their responses to increasing concentrations of Na acetate. It appears that anion inhibition applies to taste cells innervated by H fibers but not by N fibers. Taste cells innervated by N fibers use an apical Na+ channel, whereas those innervated by H fibers may use a paracellularly mediated, basolateral site of excitation.

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Salt taste responses of mouse chorda tympani neurons: evidence for existence of two different amiloride-sensitive receptor components for NaCl with different temperature dependencies

Journal of Neurophysiology ◽

10.1152/jn.1996.76.5.3550 ◽

1996 ◽

Vol 76 (5) ◽

pp. 3550-3554 ◽

Cited By ~ 26

Author(s):

Y. Ninomiya

Keyword(s):

Chorda Tympani ◽

Chorda Tympani Nerve ◽

Inhibitory Effects ◽

Strong Suppression ◽

Salt Taste ◽

Single Fibers ◽

Different Temperatures ◽

Higher Temperature ◽

Lower Temperature ◽

Mouse Taste

1. Inhibitory effects of amiloride on salt responses of single fibers of the chorda tympani nerve of the C57BL/6 strain of mice were examined at two different temperatures (approximately 12 and 24 degrees C). 2. Of 36 single fibers that responded to NaCl, 20 fibers showed strong suppression of responses to NaCl actuated by lingual treatment with amiloride (amiloride-sensitive fibers), whereas the remaining 16 fibers showed no such amiloride inhibition (amiloride-insensitive fibers). 3. Twenty amiloride-sensitive fibers were further classified into two subgroups according to the temperature dependency of their NaCl responses. In 15 of 20 fibers, amiloride-inhibitable NaCl responses were larger at 24 degrees C than at 12 degrees C, whereas the reverse was true for the remaining 5 fibers. All amiloride-insensitive fibers showed smaller responses to NaCl at 12 degrees C. 4. These results suggest that there exist two different amiloride-sensitive receptor components for NaCl with different temperature dependencies in mouse taste cells: one is more sensitive to NaCl at the higher temperature, and the other is more sensitive at the lower temperature.

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