Some people experience cold not only as feeling cold, but actually as a painful sensation. This applies even to fairly mild temperatures - anything below 20°C. A group of researchers from Lund University in Sweden has now identified the mechanism in the body that creates this connection between cold and pain. It turns out that it is based on the same receptor (TRP subtype A1) that reacts to the pungent substances in mustard and garlic. This result was reported online on November 11, 2014 in PNAS. Professor of Pharmacology Peter Zygmunt and Professor of Clinical Pharmacology Edward Högestätt have long conducted research on pain and the connection between pain and irritant substances in mustard, garlic, and chilli. In large quantities, these strong spices can cause burning or irritant sensations in the mouth and throat, and can also cause rashes and swelling. When the eyes are exposed, these spices produce strong pain and lacrimation, a property that has been exploited in pepper spray and tear gas. The reason is that the substances affect nerves that are part of the pain system and that are activated by inflammation. Ten years ago, the Lund research group identified the receptor for mustard and garlic, i.e. the way in which the pungent substances in the spices irritate the nerve cells. Since then, the question of whether this receptor also responds to cold has been a matter of debate. However, the researchers have now demonstrated that this is the case. "We have worked with Professors of Biochemistry Urban Johanson and Per Kjellbom here in Lund to extract the human receptor protein and insert it into an artificial cell membrane. There we could see that it reacted to cold," explained Professor Zygmunt. The findings increase our knowledge of the human body's temperature senses.
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