Opioid Peptides and Receptors

Abstract

Opiates, such as morphine and heroin, produce their extraordinarily potent analgesic and addictive activities by activating opioid receptors in the brain. Under physiological conditions, these G-protein-coupled receptors interact with a family of endogenous peptides. Opioid receptors and peptides form a neuromodulatory system which mainly controls responses to pain and stress as well as mood, reward, and motivation. Here we summarize our current knowledge of the molecular components of the opioid system, their mechanism of action on neurons, the structure–activity of the receptors, and the regulation of receptor signaling, as well as the role of each receptor in opioid-regulated physiology and behaviors in vivo.