Resiniferatoxin

Resiniferatoxin (RTX) is a natural, high-potency ligand that activates the capsaicin receptor in a subpopulation of primary afferent sensory neurons involved in nociception (the transmission of physiological pain). RTX causes a novel ion channel in the plasma membrane to become permeable to cations, evoking a powerful analgesic effect. Research is being conducted at the National Institutes of Health to design a novel class of analgesics from the sap of resin spurge (Euphorbia resinifera), a cactus-like plant commonly found in Morocco that contains high concentrations of RTX.