The detection of noxious stimuli (chemical, mechanical, or thermal) occurs predominantly at the peripheral terminals of primary afferent neurons. This information is ultimately transmitted to the central nervous system to evoke a perception of pain which initiates appropriate protective reflexes. The receptor for capsaicin, VR1 (vanilloid receptor 1; TRPV1 is a nonselective cation channel that resembles members of the transient receptor potential (TRP) family of ion channels. The vanilloid receptor 1 protein functions both as a receptor for capsaicin and a transducter of noxious thermal stimuli. VR1 protein is localized to small-diameter sensory neurons within the dorsal root ganglia and nerve terminals in the dorsal horn.