• Nora Hagelberg, Sargo Aalto, Lauri Tuominen, Ullamari Pesonen, Kjell Någren, Jarmo Hietala, Harry Scheinin, Antti Pertovaara, and Ilkka K Martikainen.
• Pain Clinic and Department of Anaesthesiology, Intensive Care, Emergency Care and Pain Medicine, Turku University Hospital, Turku, Finland.
• Neurosci. Lett. 2012 Jul 11;521(1):11-4.

AbstractPrevious 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.Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.

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