Wasabi is a popular condiment that complements sushi, but this form of Japanese horseradish could be developed into a new treatment for pain, a new study concludes. The green paste provides a burning sensation that can spread from the mouth up through nasal cavities and sinuses.
A protein receptor known as TRPA1 has been nicknamed "the wasabi receptor" by researchers. This structure detects irritants, such as the spicy Asian condiment, ammonia or tear gas. It then sends signals to the body, resulting in swelling, itching, burning and other common reactions.
The precise nature of the TRPA1 receptor has now been mapped by investigators for the first time. This study could help lead to a more thorough understanding of pain and the development of new medications, researchers theorize.
"The pain system is there to warn us when we need to avoid things that can cause injury, but also to enhance protective mechanisms. We've known that TRPA1 is very important in sensing environmental irritants, inflammatory pain and itch, and so knowing more about how TRPA1 works is important for understanding basic pain mechanisms," David Julius from the University of California-San Francisco (UCSF) said.
The TRPA1 protein, pronounced "Trip One," is located within the cellular membrane of sensory nerve cells. This structure detects pain within bodies caused by inflammation and tissue damage as well as irritants that enter the body from outside.
Receptor proteins within the membranes develop ion channels, which are closed off most of the time. However, when wasabi or other irritants enter the body, these pores open, allowing ions to flow, signaling to nerves that damage may be taking place. Researchers have known for a while that controlling these ion channels could lead to the development of a new generation of analgesics. However, creation of these drugs was hindered, as scientists had little knowledge of the precise structure of these channels.
Cryo-microscopy (cryo-EM), a new technique in which a stream of electrons collide with super-cold proteins, was developed to image the tiny structures.
"Cryo-EM has undergone a 'resolution revolution' that has enabled us to literally see TRP channels in all their glory. We've had some idea what TRPA1 might look like, but there's something elegant and satisfying about obtaining the structure, because seeing really is believing," said Julius.
Medicinal uses of wasabi were first detailed in "The Japanese Names of Medical Herbs," published in the year C.E. 918.
Analysis of the structure of ion channels in TRPA1 receptors was profiled in the journal Nature.
Photo: Edsel LIttle | Flickr