Involvement of nociceptin/orphanin FQ and its receptor in electroacupuncture-produced anti-hyperalgesia in rats with peripheral inflammation.
The neuropeptide nociceptin/orphanin FQ (N/OFQ), the endogenous agonist of the N/OFQ peptide receptor (NOP receptor), has been demonstrated to be involved in many physiological and pathological functions including pain regulation. In the present study, the involvement of N/OFQ-NOP receptor system in electroacupuncture (EA)-produced anti-hyperalgesia was investigated in rats with peripheral inflammation. Intrathecal (i.t.) administration of N/OFQ (15 nmol) or EA at acupoints GB30 and GB34 could significantly attenuate hyperalgesia which was induced by subcutaneously injecting complete Freund's adjuvant (CFA) into one hindpaw of rats, manifesting as decreased paw withdrawal latency (PWL) to the noxious thermal stimulus. The anti-nociceptive effect of N/OFQ or EA was significantly blocked by intrathecal injection of [Nphe(1)]nociceptin(1-13)NH(2) (20 nmol), a selective antagonist of the NOP receptor, indicating the NOP-receptor-mediated mechanism. Additionally, the combination of N/OFQ injection with EA treatment could enhance anti-hyperalgesia compared to that produced by each component alone. These findings suggested that the spinal N/OFQ-NOP system might be involved in EA analgesia, which may be one of the mechanisms underlying the anti-nociceptive effect of EA in rat's peripheral inflammatory pain.
Fu
Xin
X
Department of Integrative Medicine and Neurobiology, Institute of Acupuncture Research, Shanghai Medical College, Fudan University, P.O. Box 291, 138, Yi Xue Yuan Road, Shanghai 200032, China.
Wang
Yan-Qing
YQ
Wu
Gen-Cheng
GC
D015669:Acupuncture Points; D000704:Analysis of Variance; D000818:Animals; D001522:Behavior, Animal; D004305:Dose-Response Relationship, Drug; D004347:Drug Interactions; D015671:Electroacupuncture / Q000379:methods*; D005620:Freund's Adjuvant / Q000633:toxicity; D006358:Hot Temperature; D006930:Hyperalgesia / Q000209:etiology* / Q000628:therapy*; D007249:Inflammation / Q000139:chemically induced / Q000150:complications* / Q000188:drug therapy; D008297:Male; D018847:Opioid Peptides / Q000494:pharmacology / Q000502:physiology*; D010147:Pain Measurement / Q000379:methods; D010446:Peptide Fragments / Q000494:pharmacology; D011897:Random Allocation; D051381:Rats; D017207:Rats, Sprague-Dawley; D011930:Reaction Time / Q000187:drug effects / Q000502:physiology / Q000528:radiation effects; D011957:Receptors, Opioid / Q000502:physiology*; D000094942:Nociceptin Receptor; D000097629:Nociceptin
D005620:Freund's Adjuvant; D018847:Opioid Peptides; D010446:Peptide Fragments; D011957:Receptors, Opioid; D000094942:Nociceptin Receptor; D000097629:Nociceptin; C439964:nociceptin (1-13) amide; C000722285:Oprl1 protein, rat