Nociceptin/orphanin FQ binding increases in superficial laminae of the rat spinal cord during persistent peripheral inflammation.
Regulation of nociceptin/orphanin FQ neurotransmission in conjunction with peripheral inflammation and hyperalgesia was explored, using receptor autoradiography. Binding of [3H]nociceptin was quantified in spinal segment L4 of rats at 2, 4 and 8 days following injection of complete Freund's adjuvant (CFA) into one hind-paw. Densitometric analysis of autoradiograms showed that [3H]nociceptin binding increased in medial and lateral laminae I-II bilaterally 4 days following injection of CFA compared to untreated rats; no change in binding occurred in lamina X at the times examined. Biochemical studies confirmed that the specific binding of [3H]nociceptin to sections of rat brain was consistent with the binding characteristics of the nociceptin receptor. These results suggest that spinal nociceptin receptors are upregulated during hyperalgesia. This response may enhance endogenous mechanisms of antinociception to attenuate the hyperalgesia induced by CFA.
Department of Cell Biology and Neuroanatomy, University of Minnesota, Minneapolis 55455, USA.
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Jia
D R
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Linden
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JR
Serie
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Seybold
D000818:Animals; D002908:Chronic Disease; D007249:Inflammation / Q000378:metabolism; D008297:Male; D008565:Membrane Proteins / Q000378:metabolism; D018847:Opioid Peptides / Q000378:metabolism / Q000494:pharmacology*; D011485:Protein Binding / Q000187:drug effects; D051381:Rats; D017207:Rats, Sprague-Dawley; D011957:Receptors, Opioid / Q000819:agonists*; D013116:Spinal Cord / Q000187:drug effects / Q000473:pathology*; D000097629:Nociceptin
D008565:Membrane Proteins; D018847:Opioid Peptides; D011957:Receptors, Opioid; D000097629:Nociceptin