Nobel Prize for sensing heat

This year’s Nobel Prize for Physiology or Medicine has been jointly awarded to David Julius and Ardem Patapoutian from the University of California, San Francisco and Scripps Research in La Jolla, California, respectively for their seminal work in identifying the gene and understanding the mechanism through which our body perceives temperature and pressure.

This year’s Nobel Prize for Physiology or Medicine has been jointly awarded to two American researchers — David Julius and Ardem Patapoutian from the University of California, San Francisco and Scripps Research in La Jolla, California, respectively — for their seminal work in identifying the gene and understanding the mechanism through which our body perceives temperature and pressure.

The ability of our body to sense touch and temperature — both hot and cold — particularly noxious temperature, is essential for survival and determines how we feel, interpret and interact with our internal and external environment; chronic pain results when the pain response goes awry.

Dr. Julius utilized capsaicin, a key ingredient in hot chili peppers that induces a burning sensation, to identify a sensor in the nerve endings of the skin and the cellular mechanism that responds to uncomfortably hot temperatures. The receptor for heat gets activated only above 40 degree C, which is close to the psychophysical threshold for thermal pain, thus allowing us to react to external heat.

In 2002, five years after the heat sensor was discovered, using menthol, a natural compound in mint and other compounds that elicits the coolness sensation, the two laureates independently discovered the receptor that senses cold temperatures. Recent studies have found that discrimination between warm and cool temperatures is possible only through simultaneous activation of warmth-sensing nerve fibres and inhibition of cold-sensing nerve fibres.

Using pressure-sensitive cells, Dr. Patapoutian discovered a novel class of mechanical sensors that respond to pressure on the skin and internal organs, and the perception of touch and proprioception — the ability to feel the position and movement of our body parts. The cellular mechanism that senses touch also regulates important physiological processes including blood pressure, respiration and urinary bladder control. Besides laboratory work, significant insights have been gained by studying people carrying genetic mutations in the cellular mechanism of temperature, pain, touch and pressure sensation.

In 2002, five years after the heat sensor was discovered, using menthol, a natural compound in mint and other compounds that elicits the coolness sensation, the two laureates independently discovered the receptor that senses cold temperatures. Recent studies have found that discrimination between warm and cool temperatures is possible only through simultaneous activation of warmth-sensing nerve fibres and inhibition of cold-sensing nerve fibres.

Using pressure-sensitive cells, Dr. Patapoutian discovered a novel class of mechanical sensors that respond to pressure on the skin and internal organs, and the perception of touch and proprioception — the ability to feel the position and movement of our body parts. The cellular mechanism that senses touch also regulates important physiological processes including blood pressure, respiration and urinary bladder control. Besides laboratory work, significant insights have been gained by studying people carrying genetic mutations in the cellular mechanism of temperature, pain, touch and pressure sensation.

The discovery of pain receptors and the cellular mechanism attracted huge interest from pharmaceutical companies as they could be potential targets for novel medicines, particularly to address chronic pain. Though there are several challenges that need to be addressed before such drugs can be clinically meaningful, the hope is that newer approaches may one day bypass the hurdles.

Further research will help in understanding the functions of the receptors in a “variety of physiological processes and to develop treatments for a wide range of disease conditions”.

Refugees are not always a burden

Contrary to the general perception of refugees fleeing war-torn countries as a burden and potential trouble makers, this year’s Prize once again underscores the great contributions that some of them can make to science and other fields. Dr. Patapoutian, who is of Armenian origin, grew up in Lebanon during the country’s prolonged civil war and fled to the U.S. in 1986 as an 18-year-old. From being blissfully unaware about scientists as a career back home in Lebanon, he not only “fell in love doing basic research”, but has excelled in that to produce path-breaking discoveries in medicine.

Published in The Hindu on October 7, 2021