The Nobel Prize in Physiology or Medicine was awarded jointly on Monday to David Julius and Ardem Patapoutian, two scientists who independently discovered key mechanisms of how people sense heat, cold, touch and their own bodily movements.
Dr. Julius, a professor of physiology at the University of California, San Francisco, used a key ingredient in hot chili peppers to identify a protein in nerve cells that responds to uncomfortably hot temperatures.
Dr. Patapoutian, a molecular biologist at Scripps Research in La Jolla, Calif., led a team that, by poking individual cells with a tiny pipette, hit upon a receptor that responds to pressure, touch and the positioning of body parts.
After Dr. Julius’s pivotal discovery of a heat-sensing protein in 1997, pharmaceutical companies poured billions of dollars into looking for nonopioid drugs that could dull pain by targeting the receptors. But while research is ongoing, the related treatments have so far run into huge obstacles, scientists said, and interest from drug makers has largely dried up.
Pain and pressure were among the last frontiers of scientists’ efforts to describe the molecular basis for sensations. The 2004 Nobel Prize in Medicine was given to work clarifying how smell worked. As far back as 1967, the prize was awarded to scientists studying vision.
But unlike smell and sight, the perceptions of pain or touch are not located in an isolated part of the body, and scientists did not even know what molecules to look for. “It’s been the last main sensory system to fall to molecular analysis,” Dr. Julius said at an online briefing on Monday.
The biggest hurdle in Dr. Julius’s work was how to comb through a library of millions of DNA fragments encoding different proteins in the sensory neurons to find the one that reacts to capsaicin, the key component in chili peppers. The solution was to introduce those genes into cells that do not normally respond to capsaicin until one was discovered that made the cells capable of reacting.
In search of the molecular basis for touch, Dr. Patapoutian, too, had to sift through a number of possible genes. One by one, he and his collaborators inactivated genes until they identified the single one that, when disabled, made the cells insensitive to the poke of a tiny pipette.
Dr. Patapoutian said that he gravitated to studying the sense of touch and pain because those systems remained so mysterious. “When you find a field that’s not well understood,” he said, “it’s a great opportunity to dig in.”