Figure 8.

TRPV1 and TRPM8 neurons code for hot, cold, and warm stimuli. a, In two-plate choice assays with the fixed plate set at 25°C, TRPV1-DTR mice (red squares) exhibit marked preference for test temperatures ≥ 40°C, whereas their control littermates (open circles) display profound avoidance to 45–50°C. In contrast, TRPM8-DTR animals (blue squares) display no preference for warm and show increasing avoidance as temperature rises >35°C. b, When the fixed plate was set at 45°C, TRPM8-DTR mice (blue squares) preferred all colder temperatures, whereas TRPV1-DTR animals (red squares) were significantly more averse to cold than controls (red squares) over the 10–20°C temperature range (p < 0.01, Student's t test). c, d, Mice with combined loss of TRPV1- and TRPM8-expressing cells (TRPV1-DTR/TRPM8-DTR, purple squares) were also tested using the two-plate preference assay with the fixed plate set at 25°C (c) or 45°C (d). The double mutant animals exhibited no temperature preference across the full range of temperatures. Time at test temperature represents the fraction of time mice spent on the test plate versus the control plate. Data represent means ± SEM (n ≥ 6 animals).