Inhibition by amiloride of chorda tympani responses evoked by monovalent salts

Brand, Joseph G.; Teeter, John H.; Silver, Wayne L.

doi:10.1016/0006-8993(85)90212-4

Cited by 201 publications

(112 citation statements)

References 15 publications

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“…c T wo-lever operant taste discrimination task. d Amiloride, which inhibits a portion of the NaCl-evoked taste activity in the facial nerve (Heck et al, 1984;Brand et al, 1985;Sollars et al, 1997), completely impairs NaC l versus KC l discrimination performance (Spector et al, 1996a). e Taste aversion generalization task.…”

Section: Discussionmentioning

confidence: 99%

Behavioral Discrimination between Quinine and KCl Is Dependent on Input from the Seventh Cranial Nerve: Implications for the Functional Roles of the Gustatory Nerves in Rats

John

Spector

1998

J. Neurosci.

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The rat glossopharyngeal nerve (GL), which innervates posterior tongue taste buds, contains several physiologically defined taste fiber types; at least one type is primarily responsive to certain alkaloids (such as quinine), and another is primarily responsive to acids and salts. In contrast, the chorda tympani (CT), which innervates anterior tongue taste buds, does not appear to contain fibers that differentially respond to quinine relative to salts and acids. It was therefore predicted that GL transection should disrupt behavioral discriminations between quinine and either acids or salts. Water-restricted rats were trained to press one of two levers if a sampled taste stimulus was quinine (0.1-1.0 mM) and the second lever if the sampled stimulus was KCl (0.1-1.0 M). Sham surgery, GL transection, and sublingual and submaxillary salivary gland extirpation were found to have no effect relative to presurgical performance. Both CT transection and combined GL and CT transection caused a substantial and approximately equal decrement in discrimination performance. Removal of the gustatory branches of the seventh cranial nerve [CT and greater superficial petrosal (GSP)] nearly eliminated the discrimination of the taste stimuli, and combined transection of the CT, GL, and GSP unequivocally reduced performance to chance levels. Although these findings were not presaged by the known electrophysiology, they nonetheless compare favorably with other studies reporting little effect of GL transection on behavioral responses to quinine. These results, in the context of other discrimination studies reported in the literature, suggest that, in rats, the neural coding of taste quality depends primarily on the input of the facial nerve.

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Section: Discussionmentioning

confidence: 99%

Behavioral Discrimination between Quinine and KCl Is Dependent on Input from the Seventh Cranial Nerve: Implications for the Functional Roles of the Gustatory Nerves in Rats

John

Spector

1998

J. Neurosci.

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“…Thus, in contrast to the predictions based on CT recordings, discrimination in all four strains appeared to depend on the amiloride-sensitive transduction pathway, which, in the case of BALB/cByJ, 129P3/J, and DBA/2J (and perhaps C57BL/6 as well), may exist in taste buds innervated by nerves other than the CT. animal psychophysics; taste transduction; taste coding; C57BL/6; BALB/c; 129P3/J; DBA/2 THE TASTE OF SODIUM CHLORIDE appears to be transduced via at least two mechanisms, one which is selective for Na ϩ (and Li ϩ ) and is disrupted by the lingual application of the epithelial Na ϩ channel-blocker amiloride (e.g., Refs. 1,3,5,8,12,16,27, 39), and the other(s) which is amiloride-insensitive and cation nonselective (e.g., 12,17,20,22,30,[35][36][37]. In rats, electrophysiological recordings from the chorda tympani (CT) nerve have demonstrated that, when amiloride is applied to the lingual epithelium, the responsiveness of this nerve to sodium salts, but not to nonsodium salts, is markedly suppressed (e.g., Refs.…”

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confidence: 99%

“…1, 3,5,8,12,16,27,39), and the other(s) which is amiloride-insensitive and cation nonselective (e.g., Refs. 6 -8, 12, 17, 20, 22, 30, 35-37).…”

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Taste discrimination between NaCl and KCl is disrupted by amiloride in inbred mice with amiloride-insensitive chorda tympani nerves

Eylam¹,

Spector²

2005

American Journal of Physiology-Regulatory, Integrative and Comp

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Eylam, Shachar, and Alan C. Spector. Taste discrimination between NaCl and KCl is disrupted by amiloride in inbred mice with amiloride-insensitive chorda tympani nerves. Am J Physiol Regul Integr Comp Physiol 288: R1361-R1368, 2005 doi:10.1152/ajpregu.00796.2004.-The amiloride-sensitive salt transduction pathway is thought to be critical for the discrimination between sodium and nonsodium salts in rodents. In rats, lingual application of amiloride appears to render NaCl qualitatively indistinguishable from KCl. In this study, we tested four strains of mice for salt discriminability. In one strain (C57BL/6J), chorda tympani nerve (CT) responses to NaCl are attenuated by amiloride, and in the other three strains (BALB/cByJ, 129P3/J, DBA/2J) they are not. Under water-restriction conditions, these mice (7 mice/strain) were trained in a gustometer to lick for water from one reinforcement spout in response to a five-lick presentation of NaCl and to lick from another in response to KCl [salt concentration was varied (0.1-1 M) to render intensity irrelevant]. Mice were then tested with the stimuli dissolved in amiloride hydrochloride, and the latter was used as the reinforcer as well. Each concentration of amiloride (0.1-100 M) was used on 2 separate days with control sessions interposed. Mice from all four strains were able to discriminate NaCl from KCl reliably. Amiloride impaired this discrimination in a dose-dependent fashion. Moreover, performance on NaCl trials appeared to be more affected by amiloride than that on KCl trials in all four strains. Thus, in contrast to the predictions based on CT recordings, discrimination in all four strains appeared to depend on the amiloride-sensitive transduction pathway, which, in the case of BALB/cByJ, 129P3/J, and DBA/2J (and perhaps C57BL/6 as well), may exist in taste buds innervated by nerves other than the CT. animal psychophysics; taste transduction; taste coding; C57BL/6; BALB/c; 129P3/J; DBA/2 THE TASTE OF SODIUM CHLORIDE appears to be transduced via at least two mechanisms, one which is selective for Na ϩ (and Li ϩ ) and is disrupted by the lingual application of the epithelial Na ϩ channel-blocker amiloride (e.g., Refs. 1,3,5,8,12,16,27, 39), and the other(s) which is amiloride-insensitive and cation nonselective (e.g., 12,17,20,22,30,[35][36][37]. In rats, electrophysiological recordings from the chorda tympani (CT) nerve have demonstrated that, when amiloride is applied to the lingual epithelium, the responsiveness of this nerve to sodium salts, but not to nonsodium salts, is markedly suppressed (e.g., Refs. 3,8,12,16,27,36).Evidence supporting the importance of the amiloride-sensitive mechanism to sodium-specific taste comes from behavioral studies. Amiloride appears to render NaCl qualitatively indistinguishable from KCl in a dose-dependent fashion (e.g., Ref. 18,33). This is evident both in discrimination studies, where adulteration of the taste solutions with amiloride reduces the ability of rats to discriminate NaCl from KCl salt to chance levels (21, 33), a...

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“…The sodium-selective ion channels, or epithelial sodium channels (ENaCs), expressed by these cells can be blocked with the drug amiloride (see Brand, Teeter, & Silver, 1985;DeSimone & Ferrell, 1985;Doolin & Gilbertson, 1993;Heck, Mierson, & DeSimone, 1984;Schiffman, Lockhead, & Maes, 1983). A second transduction pathway for sodium, the amiloride-insensitive (AI) pathway, is not sodium selective but instead appears to be activated by a variety of cations, including Na ϩ , K ϩ , and NH 4 ϩ (Brand et al, 1985;DeSimone & Ferrell, 1985;Kloub, Heck, & DeSimone, 1997;Ye, Heck, & DeSimone, 1994).…”

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Anion Size Does Not Compromise Sodium Recognition by Rats After Acute Sodium Depletion.

Geran¹,

Spector²

2004

Behavioral Neuroscience

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Amiloride-insensitive sodium taste transduction is severely limited by large anions (i.e., gluconate). We found that in a brief-access taste test, sodium-depleted rats exhibited similar levels of increased licking to several sodium salts regardless of anion but did not increase licking to nonsodium salts compared with water. The enhanced licking of sodium salts was abolished in the presence of amiloride. These results suggest that the amiloride-sensitive taste transduction pathway is not only necessary but that it is also sufficient for sodium identification in rats. Sodium-depleted rats tested with amiloride initiated significantly more trials than nondepleted rats; hence, appetitive behavior was mildly potentiated by depletion, even in the absence of a sodium taste cue. Overall, these findings provide compelling support for the primacy of the amiloride-sensitive taste transduction mechanism and its associated neural pathway in the recognition of the sodium cation.

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Inhibition by amiloride of chorda tympani responses evoked by monovalent salts

Cited by 201 publications

References 15 publications

Behavioral Discrimination between Quinine and KCl Is Dependent on Input from the Seventh Cranial Nerve: Implications for the Functional Roles of the Gustatory Nerves in Rats

Behavioral Discrimination between Quinine and KCl Is Dependent on Input from the Seventh Cranial Nerve: Implications for the Functional Roles of the Gustatory Nerves in Rats

Taste discrimination between NaCl and KCl is disrupted by amiloride in inbred mice with amiloride-insensitive chorda tympani nerves

Anion Size Does Not Compromise Sodium Recognition by Rats After Acute Sodium Depletion.

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