Endorphins

Endorphins, proteins produced by the pituitary gland (at the base of the brain) inhibiting certain brain cells from transmitting impulses and thereby blocking or reducing the sensation of pain. Endorphins were discovered in the 1970s, after it was realized that morphine and other opium-derived drugs inhibited pain by attaching to particular receptor sites in the brain. Endorphins are chemically similar to the opiates and function as natural painkillers.

See also: Pituitary gland.