Endorphins

Compounds called endorphins were discovered in the nervous system that alleviate pain by interacting with pain receptors. Endorphins may someday be used in pain control without the addictive qualities and other side effects of opiates.
 John Hughes and Hans Kosterlitz England 1975 Endorphins

Compounds called endorphins were discovered in the nervous system that alleviate pain by interacting with pain receptors. Endorphins may someday be used in pain control without the addictive qualities and other side effects of opiates.