Endogenous opiates.
D000818:Animals; D001923:Brain Chemistry; D004723:Endorphins / Q000302:isolation & purification / Q000502:physiology*; D004745:Enkephalins / Q000302:isolation & purification / Q000502:physiology*; D006801:Humans; D010146:Pain / Q000503:physiopathology
D004723:Endorphins; D004745:Enkephalins