Endorphins are among the brain chemicals known as neurotransmitters, which function to transmit electrical signals within the nervous system. The word "endorphin" is a combination of "endo" and "morphine" -- meaning endogenously produced morphine, or internally produced painkiller. In 1975, John Hughes and Hans W. Kosterlitz of the University of Aberdeen isolated two naturally occurring peptides in the brain that bound tightly to the opiate receptors and named them enkephalins. The endorphin molecule was subsequently isolated from the pituitary gland. Endorphin release varies among individuals. The release may explain the comforting feelings that many people associate with this food and the craving for chocolate in times of stress. Beta-endorphin is a chemical released into the brain to help maintain homeostasis when an outside factor, such as pain, is being felt in the body.