Endorphins.
D000818:Animals; D001522:Behavior, Animal / Q000187:drug effects; D001923:Brain Chemistry; D004723:Endorphins / Q000502:physiology*; D004745:Enkephalins / Q000494:pharmacology / Q000502:physiology; D006801:Humans; D010146:Pain / Q000503:physiopathology*; D011957:Receptors, Opioid / Q000187:drug effects
D004723:Endorphins; D004745:Enkephalins; D011957:Receptors, Opioid