From winter air and tile floors to ice cream and breath mints, we experience sensations of cold on a regular basis. Yet commonplace though it is, scientists understand little about the cellular and molecular mechanisms that enable our bodies to detect cold. Recent research into heat detection revealed heat receptors in sensory nerves that populate the skin. Now new findings, published online yesterday by the journal Nature, suggest that a similar receptor responds to chilly stimuli.
The University of California at San Francisco team that conducted the research set out to investigate how plant products such as menthol elicit a cooling sensation. Their quest led them to a particular cellular doorway that, in the presence of menthol, changes the flow of ions into nerve cells. This shift produces a nerve signal that results in sensation. As it turns out, the same ion channel that responds to menthol is also activated by cold temperatures, between eight and 28 degrees Celsius.
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According to the report, this cold- and menthol-sensitive receptor (CMR1) belongs to the same so-called transient receptor potential (TRP) family of ion channels to which known heat-activated channels belong, making it a "close molecular cousin" of those receptors. The researchers note, however, that the heat receptors are activated only in the pain-producing range. Such differences in channel sensitivities, they write, "may help to explain why psychosocial thresholds for cold-evoked pain are not as distinct as they are for heat."