Flemish scientists discover pain mechanism for heat

Summary

In a breakthrough finding, researchers at KU Leuven and VIB have identified the way in which our bodies tell our brain that we are in danger of being burned

Hot, hot, hot

Researchers at the University of Leuven (KU Leuven) and Flanders’ life sciences research centre VIB have discovered the mechanism whereby humans feel pain from intense heat. The groundbreaking findings were published this week in the journal Nature.

Sensory neurons tell the brain how external stimuli are affecting our bodies. The sensory neurons involved in signalling pain have long been known. But how they detect harmful signals has remained a bit of a mystery. Until now.

It turns out that three ion channels working together within the sensory neurons are responsible for detecting pain specifically caused by heat. Ion channels in our cells create a pathway for ions to get through membranes in our bodies (pictured). Ions are electrically charged atoms or molecules that are required for many of our body’s functions, including a heartbeat.

The scientists were themselves surprised that there are three ion channels that control the sensation of pain caused by heat. If one, or even two, fail, the third continues to function, preventing burn injuries.

“We were already aware of several potential molecular heat sensors,” said Ine Vandewauw of VIB, “but none of them, when deactivated, resulted in a severe loss of heat sensing.”

Chili peppers

So the teams – led by Thomas Voets and VIB and Joris Vriends at KU Leuven – started eliminating heat-activated ion channels in mice. When they would eliminate one, a different one would respond to the same stimulus – including chemicals found in chili peppers, mustard and radish.

Only when they eliminated all three heat-activated ion channels did the mice stop showing a response to the heat-inducing chemicals. They also discovered that an inhibitor cocktail could supress the heat response.

Acute pain in response to heat is a crucial alarm signal in all mammals

- Thomas Voets of VIB

The signalling was specific for the pain response to heat, as the animals responded normally to other painful stimuli such as cold, pressure or pinpricks. “Acute pain in response to heat is a crucial alarm signal in all mammals,” explains Voets. “The presence of three redundant molecular heat-sensing mechanisms with overlapping expression in pain-sensing neurons creates a powerful fail-safe mechanism. It ensures we avoid dangerous heat.”

Ultimately, the researchers hope to use the findings to help treat chronic pain. “Millions of people worldwide suffer from ongoing, burning pain caused by nerve damage or inflammation,” explains Voets. “In such conditions, the three heat-activated ion channels can get deregulated, signalling painful heat even when there is no risk of burning.”

New drugs, he continues, that specifically temper the activity of the molecular heat detectors could lead to a safe and effective treatment for chronic pain.

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University of Leuven

Established almost six centuries ago, the University of Leuven (KU Leuven) is one of the oldest universities in the Low Countries. International rankings consistently place it among the best universities in Europe.
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