Endorphins (Endogenous Opioids)

Publication Year: 

Image retrieved from Web.squ.edu.om on October 5th, 2013.

during the early 1970s, specific receptors sites for opioid molecules were identified in the brains of experimental animals and of humans. This discovery caused scientists to question not only the nature and function of these receptors but also the reason for their existence. Most concluded that it was highly unlikely that so many species of animals would have independently evolved a set of receptors to bind compounds synthesized in a species of poppy growing only in localized parts of the world. Rather, they postulated, the opiates codeine and morphine just happened to interact with receptors that already existed in the brain to mediate the effects of a mysterious endogenous substance (is, one produced within the body).

This theorizing led to the isolation in 1975 of endogenous substances, polypeptides subsequently named enkephalins, that could bind specifically to opioid receptors. Intensive research soon revealed a whole family of similar compounds both in the brain and in certain other parts of the body. The term endorphin, derived by a contraction of "endogenous morphine," is now used to refer to these substances. Endorphins seem to act in a way similar to the opiod drugs, producing their effects by means of several different mechanisms. In some parts of the brain, they appear to act as neurotransmitters; in others, they serve as regulators of neuronal functions or as hormones.

Excerpt from page 115 of Drugs and Drug abuse by Terrence C. Cox, Michael R. Jacobs, A. Eugene LeBlanc, and Joan A. Marshman

Endorphins Endogenous Opioids, opium, morphine,