Physiology, Opioid Receptor

Excerpt

The utilization of opioids in clinical pharmacology started after the extraction of morphine from the opium poppy Papaver somniferum in 1806 with its use further intensified after the discovery of hypodermic needles in 1853. Opioids divide into two types, those being endogenous and exogenous. Some endogenous opioids that bind to the receptors are enkephalins, endorphins, endomorphins, dynorphins, and nociception/orphanin. Exogenous opioids like morphine, heroin, and fentanyl are substances that are introduced into the body and bind to the same receptors as the endogenous opioids. To date, five types of opioid receptors have been discovered-mu receptor (MOR), kappa receptor (KOR), delta receptor (DOR), nociception receptor (NOR) and zeta receptor (ZOR). Within these different types are a subset of subtypes, mu1, mu2, mu3, kappa1, kappa2, kappa3, delta1, and delta2. This report focuses on the functioning and significance of opioid receptors.