David Julius and Ardem Patapoutian receive this year’s Nobel Prize in Physiology and Medicine, respectively, for discovering receptors for temperature and touch. The two researchers had solved the question of how nerve impulses are triggered so that people perceive temperature and pressure. The winners would have added missing links to understand the complex interplay between our senses and the environment.
Sensory physiologist Julius of the University of California at San Francisco used capsaicin, a compound of chili peppers that causes a burning sensation, to identify a sensor in the nerve endings of the skin that reacts to heat, writes the Nobel Committee in Stockholm.
The protein TRPV1 (Transient Receptor Potential Cation Channel), which is located in the membranes of the nerve cells of the central and peripheral nervous system, reacts to the heat or sharp stimulus. At temperatures above 42 degrees Celsius, a low pH value below 5.9 or contact with irritants such as capsaicin, the protein opens up to a pore in the membrane and allows calcium ions to flow through the membrane. This flow of calcium ions through the ion channel triggers an action potential that propagates via the neurons to the brain and there triggers the sensory perception of “pain”.
Researchers are trying to develop new pain relievers based on their knowledge of the path that pain takes into the brain. One approach is desensitization through regular capsaicin administration. The permanent stimulation of TRPV1 dulls the pain stimulus in those affected. The development of blockers for the ion channel is also being promoted. If TRPV1 remains closed, no ions can pass through and the pain and heat signal path is cut off.
New class of receptors
The molecular biologist Patapoutian from Scripps Research in La Jolla, California discovered a new class of receptors that respond to mechanical stimuli in the skin and internal organs. PIEZO2 is the name of the membrane protein that is responsible when our skin reacts to a breath of air or when we feel the bladder level. PIEZO2 is also an ion channel. It opens when the membrane around it expands mechanically. As soon as the channel opens, the sensory cell sends signals to the brain.
So far, two PIEZO ion channels are known. PIEZO2 is primarily responsible for the perceptible sensors and the control of breathing. PIEZO1 mainly measures the cardiovascular system.
The two discoveries initiated intensive research that increased understanding of how the nervous system recognizes heat, cold and mechanical stimuli, according to the Nobel Prize Committee.
It had previously been speculated that the Nobel Prize in this category could be awarded in connection with the coronavirus pandemic. In the press conference for the announcement of the award, the committee only said that it was considering nominations for the award.
Last year the Nobel Prize in Medicine or Physiology went to Harvey J. Alter (USA), Michael Houghton (Great Britain) and Charles M. Rice (USA) for the discovery of the hepatitis C virus. Thanks to the discoveries made by the three award winners, hepatitis C can now be cured, it was said to justify. They would have found the cause of cases of chronic hepatitis and enabled blood tests and new drugs that would have saved millions of lives.
[Update: Meldung um weitere Erläuterungen ergänzt.]