Taste, Salience, and Increased NaCl Ingestion after Repeated Sodium Depletions

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.