Pain activation of human supraspinal opioid pathways as demonstrated by [11C]-carfentanil and positron emission tomography (PET).
The role of the supraspinal endogenous opioid system in pain processing has been investigated in this study using positron emission tomography imaging of [11C]-carfentanil, a synthetic, highly specific mu opioid receptor (mu-OR) agonist. Eight healthy volunteers were studied during a baseline imaging session and during a session in which subjects experienced pain induced by applying capsaicin topically to the dorsal aspect of the left hand. A pain-related decrease in brain mu-OR binding was observed in the contralateral thalamus consistent with competitive binding between [11C]-carfentanil and acutely released endogenous opioid peptides. This decrease varied directly with ratings of pain intensity. These results suggest that the supraspinal mu-opioid system is activated by acute pain and thus may play a substantial role in pain processing and modulation in pain syndromes.
Bencherif
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Department of Radiology, The Johns Hopkins University School of Medicine, JHOC 3225, 601 N Caroline Street, Baltimore, MD 21287, USA Department of Neurosurgery, The Johns Hopkins University School of Medicine, Meyer 5-109, 600 N Wolfe Street, Baltimore, MD 21287, USA Department of Neurosciences, The Johns Hopkins University School of Medicine, JHOC 3225, 601 N Caroline Street, Baltimore, MD 21287, USA.
Fuchs
P N
PN
Sheth
R
R
Dannals
R F
RF
Campbell
J N
JN
Frost
J J
JJ
D000328:Adult; D019540:Area Under Curve; D001921:Brain / Q000000981:diagnostic imaging / Q000378:metabolism; D002211:Capsaicin; D002250:Carbon Radioisotopes / Q000378:metabolism; D005283:Fentanyl / Q000031:analogs & derivatives* / Q000378:metabolism*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009294:Narcotics / Q000378:metabolism; D009434:Neural Pathways / Q000000981:diagnostic imaging / Q000378:metabolism; D010146:Pain / Q000139:chemically induced / Q000000981:diagnostic imaging* / Q000378:metabolism; D010147:Pain Measurement / Q000379:methods*; D017450:Receptors, Opioid, mu / Q000378:metabolism*; D014055:Tomography, Emission-Computed / Q000379:methods*
D002250:Carbon Radioisotopes; D009294:Narcotics; D017450:Receptors, Opioid, mu; C017114:carfentanil; D002211:Capsaicin; D005283:Fentanyl