Taste preferences are influenced by temperature and the TRPM8 thermoreceptor

Abstract

Oral temperature influences perceptual and behavioral responses to taste stimuli. Whether somatosensory processes contribute to this influence is unknown. Here we studied how stimulus temperature impacted mouse taste preferences and how these preferences were affected by the absence of TRPM8 (transient receptor potential melastatin 8). TRPM8 is a thermoreceptor supporting cool and warm temperature coding by somatosensory, including lingual trigeminal, neurons. Female and male TRPM8 gene deficient (KO) and C57BL/6J (B6) control mice (n = 69) entered thermolickometry tests that measured licking to two solutions of one taste chemical with different concentration-temperature properties across randomly interleaved brief-access (10-sec long) fluid exposure trials. Tastants were 15{degrees}C and 30{degrees}C bitter quinine (0.03 and 0.3 mM) or an appetitive sugar (sucrose or glucose, 100 and 500 mM). Mice were water-restricted or -replete during quinine and sugar tests, respectively, which were conducted separately and examined all possible concentration-temperature pairings across multiple days. Linear mixed model (LMM) analysis revealed that concentration and temperature both individually and additively affected licks emitted to quinine, with higher concentration and higher temperature (30{degrees}C) associated with the greatest reduction in quinine licks in B6 and KO mice. In contrast, LMM analysis indicated that temperature influenced licks to sugar only in KO mice, which made significantly fewer licks to higher than lower temperature sugars. Notably, KO mice also showed significantly reduced avidity to lick concentrated sugars than B6 mice. These data uncover novel roles for oral temperature and the TRPM8 thermoreceptor, and possibly its broader physiological influences, in taste preference behavior.