Expression of functional mu-opioid receptors in human osteoarthritic cartilage and chondrocytes.
There is evidence of effects of morphine on cell proliferation and intraarticular morphine produces analgesia and has an anti-inflammatory effect in chronic arthritis. The effects of opioids are mediated through the G-protein-coupled receptors affecting the cAMP pathway. We demonstrated that human osteoarthritic cartilage and cultured chondrocytes possess the mu-opioid receptor. The presence of the receptor was shown by immunodetection, polymerase chain reaction, and Western blotting. Stimulation of chondrocytes with beta-endorphin resulted in decreased phosphorylation of the transcription factor cAMP responsive element binding protein (CREB). The effect was reversed by naltrexone. The obtained results indicate that in human articular chondrocytes opioids affect, via the mu-opioid receptor, the transcription factor CREB which in turn can cause subsequent changes in gene expression.
Department of Orthopaedic Surgery, University Hospital of Northern-Norway, 9038 Tromsø, Norway. jan.elvenes@unn.no
Jan
J
Elvenes
Nenad
N
Andjelkov
Yngve
Y
Figenschau
Tore
T
Seternes
Geir
G
Bjørkøy
Oddmund
O
Johansen
D002358:Cartilage, Articular / Q000378:metabolism* / Q000473:pathology*; D002478:Cells, Cultured; D019902:Chondrocytes / Q000187:drug effects / Q000378:metabolism* / Q000473:pathology*; D046508:Culture Techniques; D017362:Cyclic AMP Response Element-Binding Protein / Q000378:metabolism; D006801:Humans; D007719:Knee Joint / Q000378:metabolism / Q000473:pathology; D009271:Naltrexone / Q000494:pharmacology; D020370:Osteoarthritis, Knee / Q000378:metabolism* / Q000473:pathology*; D017450:Receptors, Opioid, mu / Q000378:metabolism*; D014018:Tissue Distribution; D001615:beta-Endorphin / Q000494:pharmacology
D017362:Cyclic AMP Response Element-Binding Protein; D017450:Receptors, Opioid, mu; D009271:Naltrexone; D001615:beta-Endorphin