Sodium deficient diet reduces gustatory activity in the nucleus of
the solitary tract of behaving rats.
Nakamura, Kiyomi, and Ralph Norgren.
Department of Behavioral Science, College of Medicine, Pennsylvania
State University, Hershey, PA 17033-0850, USA, Tel: 717-531-6921,
Fax; 717-531-3897
APStracts 2:0103R, 1995.
The activity of single taste neurons was recorded from the nucleus of
the solitary tract before (n=41) and after (n=58) the awake, behaving
rats were switched to a sodium-free diet. During sodium deprivation,
the spontaneous activity of the neurons increased (142%), but
responses to water and sapid stimuli decreased. For all neurons in
the sample, the mean response to water decreased to 72% of its pre
-deprivation level, NaCl dropped to 53%, sucrose to 41%, citric acid
to 68%, and quinine HCl to 84%. Despite the drop in magnitude, the
response profiles of the taste neurons were not changed by the
dietary condition. In the Na-replete state, 61% of the activity
elicited by NaCl occurred in NaCl-best cells, 33% in sucrose-best
neurons. In the depleted state, these figures were 60% and 26%,
respectively. Nevertheless, at the highest concentrations tested,
deprivation did alter the relative responsiveness of the gustatory
neurons to sucrose and NaCl in specific categories of neurons.
Compared with acute preparations, sodium deprivation in awake,
behaving rats dietary produced a more general reduction in the
gustatory responses of neurons in the nucleus of the solitary tract.
The largest reductions in elicited activity occurred for the 'best
-stimulus' of a particular neuron, thus leading to smaller differences
in response magnitude across stimuli, particularly at the highest
concentrations tested.
Received 3 January 1995; accepted in final form 29 March 1995.
APS Manuscript Number R004-5.
Article publication pending Am. J. Physiol. (Regulatory Integrative
Comp. Physiology).
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 25 April 1995.