CHANGES IN CENTRAL OPIOID RECEPTOR-BINDING IN RELATION TO INFLAMMATION AND PAIN IN PATIENTS WITH RHEUMATOID-ARTHRITIS

A group of four patients with RA were examined to test the hypothesis that there is a change in the endogenous opioid system in the brain du ring inflammatory pain. Regional cerebral opioid receptor binding was quantified using the opioid receptor antagonist [C-11] diprenorphine a nd positron emission tomography (PET). In the four patients studied in and out of pain, significant increases in [C-11]diprenorphine binding were seen in association with a reduction in pain. Increases were see n in most of the areas of the brain that were sampled apart from the o ccipital cortex. Significant region-specific increases over and above the more generalized changes were also seen in the frontal, cingulate and temporal cortices in addition to the straight gyrus. These finding s are consistent with the hypothesis that there are substantial increa ses in occupancy by endogenous opioid peptides during inflammatory pai n.