Amiloride reduces the aversiveness of acids in preference tests

Abstract

Experiments were conducted to determine the relative contribution of amiloride-sensitive pathways to the aversiveness of acid stimuli in preference tests performed on male Golden Syrian hamsters. In Experiment 1 hamsters were given a choice between water and test solutions in two-bottle preference tests lasting 4 days. The results showed that although citric acid at pH 3.0–5.0 was not aversive, at pH 1.4 or 2.0 citric acid was avoided by all animals, as indicated by both consummatory behavior and licking activity. Experiment 2 was conducted to determine whether amiloride could reduce the aversiveness of citric acid in preference tests. Citric acid at pH 2.4, an aversive solution, and citric acid at pH 3.8, which was not aversive, were tested either alone or in the presence of amiloride. Amiloride (30–300 μ M), which when presented alone was neither preferred nor avoided, significantly reduced the aversiveness of citric acid at pH 2.4, similar to its effect on NaCl aversiveness. However, amiloride had no effect on intake of citric acid at pH 3.8, nor upon preference for saccharin. These results support those found in isolated hamster taste cells and from in situ taste bud recordings, which suggested that amiloride-sensitive pathways contribute to the transduction of acidic stimuli.