The peculiar flavor of the chilli pepper has played a key role in the history of the research that has won the Nobel Prize in Medicine 2021. The flavors of menthol and wasabi have also contributed to the discovery of touch and temperature receptors by the Award-winners David Julius, from the University of California at San Francisco (UCSF), and Ardem Patapoutian, from the Scripps Research Institute in La Jolla, both in California (USA).
Julius was intrigued that there was a receptor for appreciating spicy food. He identified the protein that makes it possible to identify the spicy component of the chilli, produced by the TRPV1 gene, and wondered what its function could be in the human body. “It couldn’t be that we only had it to appreciate spicy food,” he declared in January this year after receiving the Frontiers of Knowledge award from the BBVA Foundation, also shared with Ardem Patapoutian.
David Julius was surprised that the human body had a receptor for spicy food and wondered what other function it could have.
The flavor of the chilli is dominated by capsaicin, its spicy component, which is also found in padrón peppers. Julius discovered that the TRPV1 receptor, in addition to responding to the pungency of capsaicin, is a heat sensor that is activated at high temperatures. Hence, spicy flavors are identified with a burning sensation.
Following this discovery, Julius set out to find an equivalent receptor for cold. He thought that if the receptor for heat was related to a flavor, the receptor for cold might as well be. He resorted to menthol, a component of mint, as it is associated with a sensation of freshness. Just as he suspected, he discovered that the receptor for menthol is also a receptor for cold.
The chilli is related to the perception of heat; the mentor, with the cold; and the wasabi, with the pain
From there, he decided to search for the receptor for the spicy compound of wasabi, from the mustard family. He reasoned that if mustard extract had been used for pain testing for years, identifying the receptor that wasabi acts on could be helpful in understanding pain sensation, and perhaps developing new pain relievers.
The receptor for the spiciness of wasabi that Julius identified, which is the same receptor that makes you cry when you cut an onion, has been found to play a key role in the pain of inflammatory lesions. The advance has opened a line of research that studies, not intense acute pain, but persistent pain that can lead to chronic pain syndromes.
Research opens the way to new treatments for chronic pain such as muscle and joint
Independently, Ardem Patapoutian, also a Nobel laureate today, investigated the molecular basis of the sense of touch and identified other important proteins involved in pain. Specifically, he identified the Piezo proteins, which are responsible for the perception of pressure on the skin. One of these proteins, Piezo 2, causes pain that is felt, for example, when something touches the skin after suffering a sunburn.
Julius and Patapoutian’s discoveries “shed light on how to reduce acute and chronic pain associated with numerous diseases,” highlighted the minutes of the jury that awarded them the Frontiers of Knowledge award earlier this year. Several pharmaceutical companies have ongoing research to develop new pain relievers that act on these receptors and that could be useful in treating persistent forms of pain for which no good treatments are currently available, such as some muscle and joint pain relievers.
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Chilli pepper and wasabi inspired the Nobel Prize in Medicine