title: Pleasure-related analgesia activates opioid-insensitive circuits.
abstract: Recent findings suggest that pain and pleasure share common neurochemical circuits, and studies in animals and humans show that opioid-mediated descending pathways can inhibit or facilitate pain. We explored the role of endogenous opioid neurotransmission in pleasure-related analgesia. μ-Opioidergic activity was blocked with 0.2 mg/kg naloxone to assess its effects on hedonic responses to pleasant emotional pictures (International Affective Picture System) and its modulating effects on heat pain tolerance. Naloxone did not alter subjective and autonomous reactions to pleasure induction or overall mood of participants. In addition, pleasure-related increases in pain tolerance persisted after reversal of endogenous μ-opioidergic neurotransmission. Subjective pain intensity and unpleasantness ratings increased after naloxone administration. These findings suggest that, in addition to opioid-sensitive circuits, mainly opioid-insensitive pain-modulating circuits are activated during pleasure-related analgesia.
authors.affiliation: Collegium Helveticum, University of Zurich and ETH Zurich, 8092 Zurich, Switzerland. kut@collegium.ethz.ch
authors.forename: Elvan
authors.initials: E
authors.lastname: Kut
authors.forename: Victor
authors.initials: V
authors.lastname: Candia
authors.forename: Jan
authors.initials: J
authors.lastname: von Overbeck
authors.forename: Judit
authors.initials: J
authors.lastname: Pok
authors.forename: Daniel
authors.initials: D
authors.lastname: Fink
authors.forename: Gerd
authors.initials: G
authors.lastname: Folkers
mesh_terms: D000328:Adult; D000339:Affect / Q000187:drug effects / Q000502:physiology; D000698:Analgesia; D000701:Analgesics, Opioid / Q000494:pharmacology; D000704:Analysis of Variance; D001143:Arousal / Q000187:drug effects / Q000502:physiology; D001341:Autonomic Nervous System / Q000187:drug effects / Q000502:physiology; D005712:Galvanic Skin Response / Q000187:drug effects / Q000502:physiology; D006339:Heart Rate / Q000187:drug effects / Q000502:physiology; D006801:Humans; D008297:Male; D009270:Naloxone / Q000494:pharmacology; D009434:Neural Pathways / Q000502:physiology*; D018847:Opioid Peptides / Q000502:physiology*; D010146:Pain / Q000378:metabolism / Q000503:physiopathology*; D010147:Pain Measurement / Q000187:drug effects; D017288:Pain Threshold / Q000187:drug effects / Q000502:physiology*; D010775:Photic Stimulation; D057181:Pleasure / Q000502:physiology*; D011795:Surveys and Questionnaires; D009435:Synaptic Transmission / Q000187:drug effects / Q000502:physiology*
chemical_list: D000701:Analgesics, Opioid; D018847:Opioid Peptides; D009270:Naloxone