Involvement of nitric oxide in the nociception of kyotorphin, TYR-CAV and MIF-s analogues in the rat spinal cord.
The spinal analgesic effects of Kyotorphin (Kyo) and Melanocyte-inhibiting factor (MIF-l) were studied during acute pain in rats chronically implanted with intrathecal (i.t.) cannulas. Kyo (5 micrograms), t-Cav (5 micrograms), Tyr-Cav (5 micrograms), L-NAME (1500 micrograms), MIF-Cav (200-400 micrograms) and MIF-sLeu (200 micrograms) exerted antinociceptive effects in both tests. The coadministration of Kyo + L-NAME enhanced the nociceptive effect compared with L-NAME (PP) or Kyo alone (PP, TF). The combination of Tyr-Cav + L-NAME enhanced the antinociceptive effect compared with L-NAME (PP) or Tyr-Cav alone (TF, PP). MIF-l (200 micrograms) had a weak antinociceptive effect in both tests. The coadministration of MIF-Cav + L-NAME enhanced the nociceptive effect compared with L-NAME (TF) or MIF-Cav alone (TF). The combination of MIF-sLeu + L-NAME enhanced the antinociceptive effect compared with L-NAME (TF) or MIF-sLeu alone (TF, PP). The results suggest that nitric oxide (NO) is involved in the antinociceptive effects of neuropeptides in the rat spinal cord.
Institute of Physiology, Bulgarian Academy of Sciences, Sofia, Bulgaria. bocheva@iph.bio.bas.bg
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D000208:Acute Disease; D000700:Analgesics / Q000494:pharmacology; D000818:Animals; D004347:Drug Interactions; D004357:Drug Synergism; D004723:Endorphins / Q000378:metabolism* / Q000494:pharmacology; D007278:Injections, Spinal; D009075:MSH Release-Inhibiting Hormone / Q000031:analogs & derivatives* / Q000378:metabolism* / Q000494:pharmacology; D008297:Male; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology; D009569:Nitric Oxide / Q000378:metabolism*; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors; D010146:Pain / Q000188:drug therapy / Q000378:metabolism* / Q000503:physiopathology; D017288:Pain Threshold / Q000187:drug effects; D051381:Rats; D017208:Rats, Wistar; D013116:Spinal Cord / Q000187:drug effects / Q000378:metabolism*; D013997:Time Factors
D000700:Analgesics; D004723:Endorphins; C019448:kyotorphin; D009569:Nitric Oxide; D009075:MSH Release-Inhibiting Hormone; D019001:Nitric Oxide Synthase; D019331:NG-Nitroarginine Methyl Ester