title: Role of circulating opioids in the modulation of pain.
mesh_terms: D015670:Acupuncture Therapy; D000818:Animals; D001812:Blood-Brain Barrier; D002415:Cats; D002940:Circadian Rhythm; D003307:Copulation; D004594:Electrophysiology; D004723:Endorphins / Q000097:blood / Q000502:physiology*; D006358:Hot Temperature; D007016:Hypophysectomy; D009270:Naloxone / Q000494:pharmacology; D009294:Narcotics / Q000097:blood; D010146:Pain / Q000503:physiopathology*; D005082:Physical Exertion; D012726:Sexual Behavior, Animal; D013312:Stress, Physiological / Q000503:physiopathology; D001615:beta-Endorphin
chemical_list: D004723:Endorphins; D009294:Narcotics; D009270:Naloxone; D001615:beta-Endorphin