Therapeutic approach targeting TRP channels and development of anti-aspiration drugs

Aspiration pneumonia is a major health problem in the elderly. A swallowing disorder, such as a delayed triggering of the swallowing reflex, predisposes in patients with aspiration pneumonia. Swallowing reflex was delayed when the temperature of the food is close to body temperature. The actual swallowing time shortened when the temperature difference increases. The improvement of swallowing reflex by temperature stimuli could be mediated by the temperature-sensitive TRP channel at pharynx. The administration of capsaicin as an agonist stimulus of TRPV1, a warm temperature receptor, decreased the delay in swallowing reflex. Food with menthol, agonist of TRPM8 which is a cold temperature receptor, also decreased the delay in swallowing reflex. Olfactory stimulation such as black pepper was useful to improve the swallowing reflex for people with low ADL levels or with decreased consciousness. Thus, we found anti-aspiration drugs with various site of actions on the hierarchical structure of neuronal control of swallowing. By combining anti-aspiration drugs and swallowing rehabilitations, we developed a protocol to start eating more efficiently and safely. Implementation of this protocol would help avoid re-aspiration in many elderly people with aspiration pneumonia. The combination of various anti-aspiration drugs may improve the swallowing disorders and prevent aspiration pneumonia.