48-hour two-bottle preference test

Mice were caged individually and given 48 h of access to two bottles, one containing deionized water and the other containing tastant solution. After 24 h, the bottle positions were switched to avoid positional effects. The preference ratio was calculated as follows: tastant intake/total fluid intake (tastant intake + water intake). The tastant solutions for the two-bottle preference test were 300 mM NaCl (salty taste) and 1 mM denatonium (bitter taste). The tastant solutions were presented in an ascending series of concentrations. The mice were habituated by presenting two bottles that contained water for only one week before starting the preference test, and it was confirmed that the mice drank water evenly from both the bottles. Apart from the mice that died during the preference test, each mouse was tested for all solutions.