Journal of Neurophysiology, Vol 69, Issue 3 832-841, Copyright © 1993 by APS

ARTICLES

Enduring alterations in neurophysiological taste responses after early dietary sodium deprivation

M. B. Vogt and D. L. Hill
Department of Psychology, University of Virginia, Charlottesville 22903.

1. Neurophysiological taste responses from neurons in the nucleus of the solitary tract (NST) were studied in four groups of rats during chemical stimulation of the tongue with sodium and non-sodium salts, citric acid, and sucrose. The four groups of rats consisted of those fed a NaCl-deficient diet (0.03% NaCl) from day 3 postconception to at least day 50 postnatal (deprived rats), rats initially fed the NaCl-deficient diet during development and then placed on a NaCl-replete diet at adulthood for > or = 5 wk (control-deprived rats), and rats always fed the NaCl-replete diet (control rats). 2. Compared with controls, dietary NaCl deprivation instituted early in development resulted in highly attenuated average response frequencies to sodium salts (as much as 50%) but not to nonsodium salts and nonsalt stimuli. Concomitantly, most NST neurons in deprived rats responded "best" to NH4Cl and few responded best to NaCl. This is in contrast to that observed in controls, where the same proportion of neurons responded best to NaCl and best to NH4Cl. 3. Taste responses in recovered rats exhibited a hyperresponsiveness to many sodium salts compared with controls. That is, sodium salts elicited average response frequencies significantly greater (as much as 100%) than that obtained in controls. The proportions of neurons responding best to NaCl or to NH4Cl were opposite to that in deprived rats. In recovered rats, the proportion of neurons that responded best to NaCl was much greater than that which responded best to NH4Cl. 4. Rats deprived of dietary NaCl only as adults responded like controls. Therefore the environmental manipulations must occur during early periods of development. 5. These findings show that early dietary manipulations of sodium and subsequent replacement of dietary sodium have neurophysiological effects relatively selective for sodium-elicited taste responses. Furthermore, because recordings in recovered rats were obtained > or = 5 wk after feeding the NaCl-replete diet, it appears as though early NaCl deprivation permanently alters the functional organization of the NTS. Although it is likely that alterations in peripheral neural activity play a role in the functional development of NTS neurons responsive to taste stimuli, other non-activity-related factors may also be important.

This article has been cited by other articles:

				S. A. McCaughey, B. K. Giza, and M. G. Tordoff Taste and acceptance of pyrophosphates by rats and mice Am J Physiol Regulatory Integrative Comp Physiol, June 1, 2007; 292(6): R2159 - R2167. [Abstract] [Full Text] [PDF]

				J. E. Mangold and D. L. Hill Extensive Reorganization of Primary Afferent Projections into the Gustatory Brainstem Induced by Feeding a Sodium-Restricted Diet during Development: Less Is More J. Neurosci., April 25, 2007; 27(17): 4650 - 4662. [Abstract] [Full Text] [PDF]

				Y. K. Cho, M. E. Smith, and R. Norgren Low-dose furosemide modulates taste responses in the nucleus of the solitary tract of the rat Am J Physiol Regulatory Integrative Comp Physiol, October 1, 2004; 287(4): R706 - R714. [Abstract] [Full Text] [PDF]

				K. S. Curtis, E. G. Krause, D. L. Wong, and R. J. Contreras Gestational and early postnatal dietary NaCl levels affect NaCl intake, but not stimulated water intake, by adult rats Am J Physiol Regulatory Integrative Comp Physiol, June 1, 2004; 286(6): R1043 - R1050. [Abstract] [Full Text] [PDF]

				R. Tamura and R. Norgren Intracranial renin alters gustatory neural responses in the nucleus of the solitary tract of rats Am J Physiol Regulatory Integrative Comp Physiol, April 1, 2003; 284(4): R1108 - R1118. [Abstract] [Full Text] [PDF]

				D. W. Pittman and R. J. Contreras Dietary NaCl Influences the Organization of Chorda Tympani Neurons Projecting to the Nucleus of the Solitary Tract in Rats Chem Senses, May 1, 2002; 27(4): 333 - 341. [Abstract] [Full Text] [PDF]

				S. A. McCaughey and T. R. Scott Rapid induction of sodium appetite modifies taste-evoked activity in the rat nucleus of the solitary tract Am J Physiol Regulatory Integrative Comp Physiol, September 1, 2000; 279(3): R1121 - R1131. [Abstract] [Full Text] [PDF]

				R. Tamura and R. Norgren Repeated sodium depletion affects gustatory neural responses in the nucleus of the solitary tract of rats Am J Physiol Regulatory Integrative Comp Physiol, October 1, 1997; 273(4): R1381 - R1391. [Abstract] [Full Text] [PDF]