PLCβ2-Independent Behavioral Avoidance of Prototypical Bitter-Tasting Ligands

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Abstract
Using a brief-access taste assay, we show in the present report that although phospholipase C β2 knockout (PLCβ2 KO) mice are unresponsive to low- and midrange concentrations of quinine and denatonium, they do significantly avoid licking higher concentrations of these aversive compounds. PLCβ2 KO mice displayed no concentration-dependent licking of the prototypical sweetener sucrose but were similar to wild-type mice in their responses to citric acid and NaCl, notwithstanding some interesting exceptions. Although these findings confirm an essential role for PLCβ2 in taste responsiveness to sucrose and to low- to midrange concentrations of quinine and denatonium in mice as previously reported, they importantly suggest that higher concentrations of the latter two compounds, which are bitter to humans, can engage a PLCβ2-independent taste transduction pathway.