Dr. Julius has used distinctive molecules from the natural world – including toxins from tarantulas and coral snakes, and capsaicin, the molecule that produces the “heat” in chili peppers – to understand how signals responsible for temperature and pain sensation are transmitted by neural circuits to the brain.
In his research Dr. Julius has homed in on a class of proteins called TRP (pronounced “trip”) ion channels to discover how the chemical compound responsible for the spicy heat of chili peppers – called capsaicin – elicits a burning sensation when eaten or touched. The research led to the identification and cloning of the specific protein responsible, named TRPV1. On the flip side, Dr. Julius has used menthol, a natural cooling agent, to identify a receptor for “real” cold. This protein, named TRPM8, is a close molecular cousin of TRPV1, pointing to a common mechanism for sensing temperature. As in the case of TRPV1, this ion channel contributes to hypersensitivity to cold, such as that experienced after chemotherapy or other types of nerve injury.
Somatosensation, our sense of touch and pain, serves as a warning system to guard us against injury. While critical to our survival and well-being, this system can become hypersensitive, resulting in chronic pain. This work helps to explain how such positive and negative aspects of pain sensation arise – insight that is critical to understanding the genesis of chronic pain syndromes. One indication of the importance of this work to medicine is the interest in TRP channels as potential targets for a new generation of painkillers.