AUTHOR=Üçeyler Nurcan , Buchholz Hans-Georg , Kewenig Susanne , Ament Stephan-Johann , Birklein Frank , Schreckenberger Mathias , Sommer Claudia 

TITLE=Cortical Binding Potential of Opioid Receptors in Patients With Fibromyalgia Syndrome and Reduced Systemic Interleukin-4 Levels – A Pilot Study

JOURNAL=Frontiers in Neuroscience

VOLUME=14

YEAR=2020

URL=https://www.frontiersin.org/journals/neuroscience/articles/10.3389/fnins.2020.00512

DOI=10.3389/fnins.2020.00512

ISSN=1662-453X

ABSTRACT=<p><bold>Objective:</bold> We investigated cerebral opioid receptor binding potential in patients with fibromyalgia syndrome (FMS) using positron-emission-tomography (PET) and correlated our results with patients’ systemic interleukin-4 (IL-4) gene expression.</p><p><bold>Methods:</bold> In this pilot study, seven FMS patients (1 man, 6 women) agreed to participate in experimental PET scans. All patients underwent neurological examination, were investigated with questionnaires for pain, depression, and FMS symptoms. Additionally, blood for IL-4 gene expression analysis was withdrawn at two time points with a median latency of 1.3 years. Patients were investigated in a PET scanner using the opioid receptor ligand F-18-fluoro-ethyl-diprenorphine ([18F]FEDPN) and results were compared with laboratory normative values.</p><p><bold>Results:</bold> Neurological examination was normal in all FMS patients. Reduced opioid receptor binding was found in mid cingulate cortex compared to healthy controls (<italic>p</italic> &lt; 0.005). Interestingly, three patients with high systemic IL-4 gene expression had increased opioid receptor binding in the fronto-basal cortex compared to those with low IL-4 gene expression (<italic>p</italic> &lt; 0.005).</p><p><bold>Conclusion:</bold> Our data give further evidence for a reduction in cortical opioid receptor availability in FMS patients as another potential central nervous system contributor to pain in FMS.</p>