High dietary sodium enhances gustatory nerve activity and behavioral responses to NaCl.
Neural and behavioral taste responses to NaCl were studied in rats receiving a high-salt diet. Salt preferences and voluntary sodium intake were measured by the 24-h two-bottle choice method over a wide concentration range of NaCl solutions. As expected, the salt-loaded rats showed lower preference responses for all the solutions tested, which were presented in ascending order from 0.001 to 1.0 M NaCl. However, they freely ingested significantly greater amounts of sodium than the controls by drinking larger volumes of saline solution throughout the hypotonic concentration range, from 0.001 to 0.1 M NaCl. They showed lower voluntary intake of sodium only for isotonic and hypertonic solutions. Electrophysiological recordings from the chorda tympani nerve showed that the taste responses of the salt-loaded rats were greater in magnitude than those of the controls, and the neural stimulus-response function of the experimental group had a significantly steeper slope but no apparent difference in threshold. These experiments indicate that salt-loaded rats have enhanced appetitive responses to NaCl that may be mediated by increased sensory input.
Priehs
T W
TW
Department of Physiology, Michigan State University, East Lansing 48824.
Mooney
K J
KJ
Bernard
R A
RA
D000818:Animals; D001522:Behavior, Animal / Q000187:drug effects*; D004032:Diet; D004435:Eating; D008297:Male; D009424:Nervous System Physiological Phenomena; D009994:Osmolar Concentration; D051381:Rats; D011919:Rats, Inbred Strains; D012964:Sodium / Q000008:administration & dosage* / Q000378:metabolism / Q000494:pharmacology; D012965:Sodium Chloride / Q000494:pharmacology*; D013649:Taste / Q000502:physiology*
D012965:Sodium Chloride; D012964:Sodium