Current concepts of nociception: nociceptive molecular sensors in sensory neurons

Abstract

A large number of channels that are in some way linked to sensory transduction including nociception have been discovered in recent years. This review summarizes newly discovered channels that are implicated in nociception. Furthermore, details are discussed with emphasis on their possible application to clinical use as analgesics. Studies with null mutant animals deficient in these channel genes reveal that the channels are indeed implicated in physiological as well as pathological nociception. Many transient receptor potential channels are thermosensors that detect cold, warm and hot temperatures. These channels are activated not only by natural chemicals such as capsaicin, menthol, and camphor, but by various inflammatory signaling pathways. The acid-sensing ion channel and P2X channel that detect extracellular acidosis and ATP are also implicated in some types of pain. Voltage-gated sodium or calcium channels draw attention because of their involvement in neuropathic pain.