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.
Bocheva
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Institute of Physiology, Bulgarian Academy of Sciences, Sofia, Bulgaria. bocheva@iph.bio.bas.bg
Lazarova
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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