Abstract
Capsaicin is a constituent of chili pepper that induces the burning sensation on the tongue. The site of action of capsaicin was discovered to be the transient receptor potential vanilloid receptor subtype 1 (TRPV1) that resides on the membranes of pain- and heat-sensing primary afferent sensory nerves. Immunohistochemical study of the stomach revealed that nerve fibers expressing TRPV1 exist along gastric glands in the mucosa, around blood vessels in the submucosa, in the myenteric plexus, and in the smooth muscle layers. Appropriate capsaicin protects gastric mucosa, but excessive amounts cause gastric damage. Numerous TRPV1 axons were also observed in esophagus, colon and rectum. Capsaicin is not only felt on the tongue, but throughout the digestive tract. It is good for our health if we consume appropriate spices. In this presentation, menthol receptor TRPM8 in gut is also introduced.
Visceral sensory hypersensitivity is induced during gastrointestinal inflammation. The increased TRPV1-expressing nerve fibers in the gut mucosa are involved in the visceral hypersensitivity in colitis model animals. Abnormalities of primary afferent nerve fibers are strongly associated with the visceral hypersensitivity in gastrointestinal disease. Therefore, when the gastrointestinal tract is upset, consuming a lot of spices is not good for the integrity of the digestive tract.
