Rapid induction of sodium appetite modifies taste-evoked activity in the rat nucleus of the solitary tract.
Sodium-deprived rats develop a salt appetite and show changes in gustatory responses to NaCl in the periphery and brain stem; salt-sensitive neurons respond less to hypertonic NaCl than do corresponding cells in replete controls. By administering DOCA and renin, we generated a need-free sodium appetite quickly enough to permit us to monitor the activity of individual neurons in the nucleus of the solitary tract before and after its creation, permitting a more powerful within-subjects design. Subjects received DOCA pretreatment followed by an intracerebroventricular infusion of renin. In animals that were tested behaviorally, this resulted in elevated intake of 0.5 M NaCl. In neural recordings, renin caused decreased responding to hypertonic NaCl across all neurons and in the salt-sensitive neurons that were most responsive to NaCl before infusion. Most sugar-sensitive cells, in contrast, gave increased phasic responses to NaCl. These results confirm that sodium appetite is accompanied by decreased responding to NaCl in salt-sensitive neurons, complemented by increased activity in sugar-sensitive cells, even when created rapidly and independently of need.
McCaughey
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SA
Monell Chemical Senses Center, Philadelphia, Pennsylvania 19104, USA. mccaughey@monell.org
Scott
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TR
D000143:Acids / Q000494:pharmacology; D000200:Action Potentials / Q000502:physiology; D000804:Angiotensin II / Q000378:metabolism; D000818:Animals; D001066:Appetite / Q000187:drug effects / Q000502:physiology*; D002241:Carbohydrates / Q000494:pharmacology; D003900:Desoxycorticosterone / Q000494:pharmacology; D004327:Drinking Behavior / Q000187:drug effects / Q000502:physiology; D004594:Electrophysiology; D005071:Evoked Potentials / Q000502:physiology; D005247:Feeding Behavior / Q000187:drug effects / Q000502:physiology; D008297:Male; D009475:Neurons, Afferent / Q000187:drug effects / Q000502:physiology; D051381:Rats; D017208:Rats, Wistar; D012083:Renin / Q000494:pharmacology; D017673:Sodium Chloride, Dietary / Q000494:pharmacology*; D017552:Solitary Nucleus / Q000166:cytology / Q000502:physiology*; D013268:Stimulation, Chemical; D013649:Taste / Q000187:drug effects / Q000502:physiology*
D000143:Acids; D002241:Carbohydrates; D017673:Sodium Chloride, Dietary; D000804:Angiotensin II; D003900:Desoxycorticosterone; D012083:Renin