Effects of melatonin on orphanin FQ/nociceptin-induced hyperalgesia in mice.
The pain modulatory properties of melatonin (MT) are generally recognized but the detail of the interaction between melatonin and opioid system in pain regulation is not fully understood. The present study was undertaken to investigate the modulatory effect of melatonin (MT) on the hyperalgesic effect of Orphanin FQ/Nociceptin (OFQ/NC, NC), a member of opioid peptide family. Intracerebroventricular (i.c.v.) administration of NC (10 microg/mouse) induced significant hyperalgesic effect in tail-flick test in mice; i.c.v. (5, 10, 50 microg/mouse) or intraperitoneal (i.p.) (5, 10, 50 mg/kg) co-injection of melatonin dose-dependently reversed NC-induced hyperalgesia and showed a profound analgesic effect. The antihyperalgesia effect of MT could be significantly antagonized by i.c.v. co-injection of luzindole (10 microg/mouse) (an antagonist of MT receptor) or naloxone (10 microg/mouse) (antagonist of traditional opioid receptor). Taken together, all the results suggested that MT could produce a luzindole and naloxone sensitive reversing effect on NC-induced hyperalgesia at supraspinal and peripheral level in mice. The augmentation effect of MT on the traditional opioid system may be one of the mechanisms of this antihyperalgesia action induced by MT. The present work will help to elucidate the mechanism of the pain modulation effect of MT, and also will help to represent new interesting modulating therapeutic targets for the relief of pain.
Department of Biochemistry and Molecular Biology, School of Life Science, Lanzhou University, 222 Tian Shui South Road, Lanzhou 730000, People's Republic of China.
Ting
T
Wang
Shi-Rong
SR
Li
Xu
X
Dai
Ya-Li
YL
Peng
Qiang
Q
Chen
Rui
R
Wang
D000704:Analysis of Variance; D000818:Animals; D001522:Behavior, Animal; D004305:Dose-Response Relationship, Drug; D004347:Drug Interactions; D006930:Hyperalgesia / Q000139:chemically induced* / Q000188:drug therapy*; D007276:Injections, Intraventricular / Q000379:methods; D007279:Injections, Subcutaneous / Q000379:methods; D008297:Male; D008550:Melatonin / Q000008:administration & dosage*; D051379:Mice; D018847:Opioid Peptides / Q000008:administration & dosage*; D010147:Pain Measurement / Q000379:methods; D000097629:Nociceptin
D008550:Melatonin; D018847:Opioid Peptides; D000097629:Nociceptin