Body sensor reacts to chili and chilly
One of the body’s cold sensors reacts as well to frigid air as to a hot chili pepper.
You wouldn’t think that a strong mustard and burning wasabi have much to do with cool temperatures, but a newly discovered protein receptor reacts to all these.
The receptor TRPA1 (Transient receptor potential channel, subtype A1) reacts not just to mustard, garlic and wasabi (horseradish), but also to temperatures below 20°C, according to a discovery made by Swedish and German scientists.
This could help researchers find new medications and treatments for people who are hypersensitive to coldness.
Cold sensitivity as a side effect
“This is a very common complaint among patients with chronic pains or with diseases that affect the nerve system, such as diabetes,” explains Edward Högestätt, professor of clinical pharmacology at Sweden’s Lund University, in a press release.
“Patients who are treated with chemotherapy can also become hypersensitive to cold temperatures as a side effect of the medicine. The discomfort and pain can start at slightly cool temperatures within the range of temperatures which we know triggers reactions in the mustard and garlic receptor.”
The third temperature receptor
Högestätt and fellow researchers at Lund University collaborated in this study with German colleagues. TRPA1 was injected in a synthetic cell membrane so that the reactions to the stimuli could be analysed in detail.
Although a number of TRP proteins have been suggested as possible temperature receptors, science had until now only found two – the menthol receptor (TRPM8) and the chili pepper receptor (TRPV1). The discovery of a third will provide new knowledge about how the body reacts to different temperatures.
Sensors cover pleasant and unpleasant coldness
“We already know that the chili pepper receptor not only reacts to chilies, but also to temperatures above 42° C with the same reaction as when one is burned by a flame. The menthol receptor reacts at temperatures below 28° C, which are experienced as cooling,” explains Peter Zygmunt, a professor of pharmacology at Lund University.
“Thus, mammals have at least two cold sensors that, together, cover pleasant (TRP subtype M8) and unpleasant (TRP subtype A1) cold temperatures,” the scientists conclude in their report.
“Our findings add to the understanding of how the temperature sense is organised and its role in pain associated with cold hypersensitivity.”
The pharmaceutical industry is working to develop new medications that block TRPA1 to prevent pain, itching or reactions to chemical substances in the respiratory organs. But the researchers hope a beneficial effect of these drugs could also be a reduction in thermal sensitivity.
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Read the article in Norwegian at forskning.no
Translated by: Glenn Ostling
