title: Association of striatal dopamine D2/D3 receptor binding potential with pain but not tactile sensitivity or placebo analgesia.
abstract: Striatal dopamine D2/D3 receptors have been suggested to play a role in pain sensitivity and placebo effect. We studied whether the association of dopamine D2/D3 receptor binding potential (BP) with sensory thresholds is specific to the modality of pain, and whether striatal dopamine D2/D3 receptor BP predicts the magnitude of placebo analgesia. Pain and tactile thresholds, and placebo analgesia were assessed in eight healthy human male subjects who had previously participated in a dopamine D2/D3 receptor positron emission tomography study with [11C]raclopride. The results show that the cutaneous heat pain threshold was inversely correlated with dopamine D2/D3 receptor BP in the right putamen, but responses to tactile stimulation did not correlate with striatal dopamine D2/D3 receptor BP. Placebo-induced elevation of the heat pain threshold did not correlate with striatal dopamine D2/D3 receptor BP. These results suggest that the influence of striatal dopamine D2/D3 receptors on sensory thresholds is selective for the modality of pain. Moreover, striatal dopamine D2/D3 receptor BP appears not to predict individual's analgesic response to placebo.
authors.affiliation: Department of Physiology, University of Turku, Turku, Finland.
authors.forename: Ilkka K
authors.initials: IK
authors.lastname: Martikainen
authors.forename: Nora
authors.initials: N
authors.lastname: Hagelberg
authors.forename: Heikki
authors.initials: H
authors.lastname: Mansikka
authors.forename: Jarmo
authors.initials: J
authors.lastname: Hietala
authors.forename: Kjell
authors.initials: K
authors.lastname: Någren
authors.forename: Harry
authors.initials: H
authors.lastname: Scheinin
authors.forename: Antti
authors.initials: A
authors.lastname: Pertovaara
mesh_terms: D000328:Adult; D000698:Analgesia / Q000379:methods; D001667:Binding, Competitive / Q000502:physiology; D003342:Corpus Striatum / Q000378:metabolism*; D018492:Dopamine Antagonists / Q000493:pharmacokinetics; D007839:Functional Laterality / Q000502:physiology; D006801:Humans; D006930:Hyperalgesia / Q000378:metabolism / Q000503:physiopathology; D008297:Male; D010146:Pain / Q000378:metabolism* / Q000503:physiopathology; D017288:Pain Threshold / Q000502:physiology; D010812:Physical Stimulation; D015990:Placebo Effect; D011699:Putamen / Q000378:metabolism; D020891:Raclopride / Q000493:pharmacokinetics; D017448:Receptors, Dopamine D2 / Q000378:metabolism*; D050637:Receptors, Dopamine D3; D012684:Sensory Thresholds / Q000502:physiology*; D014110:Touch / Q000502:physiology*
chemical_list: C493593:DRD3 protein, human; D018492:Dopamine Antagonists; D017448:Receptors, Dopamine D2; D050637:Receptors, Dopamine D3; D020891:Raclopride