PLCβ2-Independent behavioral avoidance of prototypical bitter-tasting ligands

Using a brief-access taste assay, we show in the present report that although phospholipase C beta 2 knockout (PLC beta 2 KO) mice are unresponsive to low- and midrange concentrations of quinine and denatonium, they do significantly avoid licking higher concentrations of these aversive compounds. PLC beta 2 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 PLC beta 2 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 PLC beta 2-independent taste transduction pathway.