Something of interest from a couple of years ago:
Several years ago, the specific receptors that allow us to detect heat were identified in nerve cells. Closely related to the capsaicin receptor (TRPV1), TRPV2 is an ion channel that, upon activation by heat, allows positively-charged ions to enter neurons. This creates a potential difference across the cell membrane and therefore an electrical current. Given that these two receptors are closely related, it isn’t that surprising that exposure to capsaicin, the active ingredient in chili peppers, is sensed as “hot.”
Now a new paper published in Nature has shown that on the other end of the temperature spectrum, cold is detected by the same ion channel that is activated by menthol. Known as TRPM8, the ion channel is activated both by menthol, a compound found in mint, and by temperatures below 26? C. The researchers from UCSF, the Medical College of Wisconsin, and Yale have shown that isolated, cultured nerve cells that express TRPM8 react to cooling stimuli, but cells cultured from mice lacking TRPM8 do not. Further, the mice lacking TRPM8 are much less sensitive to cold than their normal equivalents.