Chemical Senses Advance Access originally published online on November 23, 2005
Chemical Senses 2006 31(1):33-41; doi:10.1093/chemse/bjj003
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Taste, Salience, and Increased NaCl Ingestion after Repeated Sodium Depletions
Department of Psychology and Program in Neuroscience, The Florida State University, Tallahassee, FL 32306-1270, USA
Correspondence to be sent to: Kathleen S. Curtis, Department of Psychology and Program in Neuroscience, The Florida State University, Tallahassee, FL 32306-1270, USA. e-mail: curtis{at}psy.fsu.edu
Previous studies have shown that repeated sodium depletions using the natriuretic–diuretic furosemide induce progressive increases in NaCl ingestion. We investigated the role of taste in this behavioral sensitization in Sprague–Dawley rats using short-term lickometer testing along with 2-h stimulated intake tests. Our results show maximal licking across a range of NaCl concentrations after each of the three depletions, regardless of whether the solutions contained sucrose or were presented alone. Similarly, the presence of sucrose did not affect stimulated NaCl intake in long-term tests, although ingestion of NaCl solutions increased progressively with successive depletions. Finally, both licking and ingestion returned to baseline levels during need-free conditions. These results suggest that sodium imbalance acutely increases the salience of sodium taste and thereby the likelihood of NaCl ingestion, which may, in turn, contribute to progressive increases in NaCl intake that occur with multiple furosemide-induced sodium depletions.
Key words: furosemide, lickometer, salt appetite, sensitization, Sprague–Dawley rats