title: Striatal μ-opioid receptor availability predicts cold pressor pain threshold in healthy human subjects.
abstract: Previous PET studies in healthy humans have shown that brain μ-opioid receptor activation during experimental pain is associated with reductions in the sensory and affective ratings of the individual pain experience. The aim of this study was to find out whether brain μ-opioid receptor binding at the resting state, in absence of painful stimulation, can be a long-term predictor of experimental pain sensitivity. We measured μ-opioid receptor binding potential (BP(ND)) with μ-opioid receptor selective radiotracer [(11)C]carfentanil and positron emission tomography (PET) in 12 healthy male subjects. Later, we recruited these subjects to participate in a separate psychophysical testing session to measure cold pressor pain threshold, cold pressor pain tolerance and tactile sensitivity with von Frey monofilaments. We used both voxel-by-voxel and region-of-interest image analyses to examine the potential associations between μ-opioid receptor BP(ND) and psychophysical measures. The results show that striatal μ-opioid receptor BP(ND) predicts cold pressor pain threshold, but not cold pressor pain tolerance or tactile sensitivity. This finding suggests that striatal μ-opioid receptor density is involved in setting individual pain threshold.
authors.affiliation: Pain Clinic and Department of Anaesthesiology, Intensive Care, Emergency Care and Pain Medicine, Turku University Hospital, Turku, Finland.
authors.forename: Nora
authors.initials: N
authors.lastname: Hagelberg
authors.forename: Sargo
authors.initials: S
authors.lastname: Aalto
authors.forename: Lauri
authors.initials: L
authors.lastname: Tuominen
authors.forename: Ullamari
authors.initials: U
authors.lastname: Pesonen
authors.forename: Kjell
authors.initials: K
authors.lastname: Någren
authors.forename: Jarmo
authors.initials: J
authors.lastname: Hietala
authors.forename: Harry
authors.initials: H
authors.lastname: Scheinin
authors.forename: Antti
authors.initials: A
authors.lastname: Pertovaara
authors.forename: Ilkka K
authors.initials: IK
authors.lastname: Martikainen
mesh_terms: D000328:Adult; D002250:Carbon Radioisotopes; D003080:Cold Temperature; D003342:Corpus Striatum / Q000000981:diagnostic imaging / Q000378:metabolism*; D005283:Fentanyl / Q000031:analogs & derivatives / Q000378:metabolism; D006801:Humans; D008297:Male; D010146:Pain / Q000503:physiopathology*; D017288:Pain Threshold; D049268:Positron-Emission Tomography; D019275:Radiopharmaceuticals / Q000378:metabolism; D017450:Receptors, Opioid, mu / Q000819:agonists / Q000378:metabolism*; D012016:Reference Values; D014110:Touch
chemical_list: D002250:Carbon Radioisotopes; D019275:Radiopharmaceuticals; D017450:Receptors, Opioid, mu; C017114:carfentanil; D005283:Fentanyl