Temperature effects on taste preferences are influenced by TRPM8.

Taste perception is influenced by stimulus and oral temperature. Change in oral temperature modulates trigeminal neurons. Whether trigeminal thermal sensing interacts with taste is unknown. Here we studied temperature influences on mouse taste preferences and how they could change following silencing of TRPM8 (transient receptor potential melastatin 8) - a thermoreceptor supporting cool and warm temperature coding by trigeminal neurons. Female and male TRPM8 gene deficient and C57BL/6J (B6) control mice (n = 69) entered thermolickometry tests where they sampled taste solutions at cool (15°C) and warm (30°C) temperatures during brief-access (10-sec long) exposure trials, which capture oral sensory/tongue control of licking behavior. Taste solutions included innately avoided bitter quinine (0.03 and 0.3 mM) and preferred sugars (sucrose or glucose, 100 and 500 mM). Mice were respectively maintained under water restriction or water-replete conditions during quinine and sugar tests, which were conducted separately. Analyses revealed that 15°C enhanced, while 30°C reduced, licks to quinine in both B6 and TRPM8 deficient mice, which responded similarly (p > 0.05). In contrast, licks to static concentrations of sugars trended towards enhancement by 30°C, compared to 15°C, in male B6 mice but were suppressed, and inhibited, by 30°C (p < 0.05) in male TRPM8 deficient mice. This result agrees with prior studies that show warmth normally facilitates sweetness and that 30°C stimulation of oral tissues becomes anomalously aversive in TRPM8 deficient mice. These data provide initial evidence that TRPM8 thermosensory influences interact with sugar taste preferences, which may reflect a trigeminal-taste cross-modal phenomenon.