Endorphins, Brain Peptides That Act like Opiates

A few years ago it was established that opiates bind to the cell membrane of some of the neurons of the central nervous system. These synaptosomal opiate receptors were shown, in all the vertebrates studied, to be distributed in discrete localizations of the brain. These areas, perhaps not too surprisingly, correspond to well characterized anatomic pathways and structures long recognized as involved in pain perception. The next obvious question was, "Why should there be in the brain of man receptors for the alkaloids of the poppy?" The logical answer was that these receptors were probably there not to accept the . . .