Fig. 6: OTOP1 is necessary for the behavioral aversion to NH4Cl mediated by Type III TRCs.
From: The proton channel OTOP1 is a sensor for the taste of ammonium chloride
a Schematic showing the mouse taste behavior setup using a Davis rig lickometer. In each experiment, mice were given the opportunity to lick at the control solution (artificial saliva), and multiple concentrations of the same chemical tastant, presented in random order. b Mice were water-deprived for 24 h (day 1), acclimatized to the rig on day 2, and then tested for three consecutive days with 23 h water deprivation between them. c Average data (mean ± SEM) of lick numbers, normalized to that of artificial saliva, for NH4Cl (50–500 mM), citric acid (1–30 mM), and quinine (0.1–3 mM). Mouse strains were wild-type (gray), Skn-1a−/− (blue), Otop1−/− (red), and Skn-1a−/− Otop1−/− (double knockout; purple). Otop1−/− mice showed a reduction in taste aversion to 300 mM NH4Cl; Skn-1a−/− mice, were still sensitive to but showed a reduced aversion to 300 and 500 mM NH4Cl. Skn-1a−/− Otop1−/− showed no aversion to any of the concentrations of NH4Cl, while they retained aversion to citric acid. Mice lacking Type II TRCs Skn-1a−/− showed no aversion to the bitter compound quinine, as expected. Statistical significance as compared with wild-type determined by two-way ANOVA with TUKEY correction for multiple comparisons. n = 36(left, right) and 37(middle) mice for wild-type, n = 15 (left, right) and 16 (middle) mice for Otop1−/−, n = 13 (left) and 12 (middle, right) mice for Skn-1a−/−, n = 8 (left, middle, right) mice for double knockout.
