Degeneration of infrared receptor terminals of snakes caused by capsaicin.

Capsaicin, the main pungent ingredient in hot peppers (genus Capsicum), caused degeneration of the infrared receptor terminals in infrared sensitive snakes, Trimeresurus flavoviridis, when it was applied perineurally to a branch of the trigeminal nerve. The degeneration of the terminals was found 6 h after the application. This finding suggests that capsaicin stimulates this infrared receptor terminal, a kind of warm receptor terminal.