Spicy Foods Lead the Way to Pain Relief

Spicy food may hold more power than just adding a little zest to a meal. Researchers have uncovered a key interaction that is responsible for the sensations of pain and heat.

Senior author, Jie Zheng, PhD, and colleagues from the UC Davis Health System studied what happens when capsaicin, the active compound in chili peppers, binds with the transient receptor potential cation channel subfamily V member 1 (TRPV1) channel. This pathway that activates after consuming a spicy food is the same one that charges up after an injury or inflammatory response.

“While we have known that capsaicin binds to the TRPV1 receptor with exquisite potency and selectivity, we were missing important atomic level details about exactly how the capsaicin molecule interacts with TRPV1,” Zheng, professor of physiology and membrane biology at UC Davis, said in a news release.

The team examined the TRPV1-capsaicin relationship using computer models that focus on atomic force fields and existing low resolution 3D reconstructions. Computational docking allowed the researchers to view the 2 components while they interacted, which ultimately helped them identify the structural areas where they bind, according to the study published in Nature Chemical Biology.

“The electron density observed in the cryo electron microscopy structure of the TRPV1-capsaicin complex is much smaller in size compared to the chemical structure of capsaicin,” first author Fan Yang, postdoctoral fellow at UC Davis, explained.

While hot peppers contain capsaicin, sweet peppers have a similar component called capsiate. However, it does not bind to TRPV1 very well, which may explain why it is not spicy and measures in at 16,000 on the Scoville pungency scale. Even though capsaicin overwhelms that number with 16 million, it does not activate other sensing channels. In fact, animals such as birds do not have certain interaction areas, which allow them to consume spicy foods without the effect.

“It is thought that the presence of capsaicin is an evolutional advantage for plants, protecting them from species that would eat the leave while allowing birds to ingest the peppers to spread the seed” Zheng said.

The researchers also used other methods to verify the molecular architecture. Their findings suggest that just like a person can get used to a spicy dish, the body can adapt and become less sensitive to pain. Therefore, this provides a potential jumping off point for developing improved pain relief drugs.