Journal of Clinical and Experimental Ophthalmology
Open Access

Endogenous Opioids

Endogenous opioids are enkephalins and endorphins that are primarily produced in the brain and have multiple actions throughout the body. Enkephalins and endorphins act at opioid receptors and their activity can be blocked by opioid antagonists

GLOSSARY. The endogenous opioid system consists of 3 families of opioid peptides, β-endorphin, enkephalins, and dynorphins, and 3 families of receptors, μ (MOR), δ (λ, DOR), and κ (KOR)

Endogenous opioids: opioid peptides (e.g. endorphin, enkephalin, dynorphin) produced by the body that act on opioid receptors throughout the central nervous system to cause a variety of effects, including pain relief, reduced anxiety, and enhanced mood (effects similar to those of opiate drugs).

Endogenous opioids activate opioid receptors on the surface of nerve cells and the insides of the cells. Opioid drugs, on the other hand, activate receptors in these locations and additional parts of the cell.