Definition of Endorphin

Endorphin: One of the body's own painkillers, an opioid (morphine-like) chemical produced by the body that serves to suppress pain.

Endorphins are manufactured in the brain, spinal cord, and many other parts of the body. They are released in response to neurotransmitters and bind to certain neuron receptors (the same ones that bind opiate medicines). Endorphins act as analgesics (diminishing the perception of pain) and as sedatives.

Chemically, endorphins are peptides (amino acid chains that are shorter than proteins) and they are rapidly inactivated by enzymes called peptidases.