Ausência de efeito antinociceptivo decorrente da administração intravenosa de crotalfina em comparação com morfina, U50-488H ou fenilbutazona em equinos submetidos à estimulação térmica da pele íntegra

Crotalphine is a novel analgesic peptide that acts on kappa and delta opioid receptors providing powerful analgesia in rats submitted to inflammatory, neuropathic or oncologic pain model. Maybe crotalphine can be used to treat pain in other species. So, the aim of this study was to evaluate nociceptive response at scapular and isquiatic region of horses treated with crotalphine, morphine, U50-488H or phenylbutazone and submitted to thermal stimulation in complete skin. Eighteen Arabian horses were allocated in five experimental groups: GC (5mL NaCl 0.9%), GCRO (3.8ng.kg-1 crotalphine), GK (160 µg.kg-1 U50-488H), GM (0.1mg.kg-1 morphine) and GP (4.4mg.kg-1 phenylbutazone). Animals were submitted to inflammatory pain model by thermal stimulation (140°C) and during 24h latency to skin twitch at scapular and isquiatic region were evaluated. The U50-488H produced antinociceptive effect at isquiatic region along two hours, but, in other moments of GK and in the other groups there was not antinociceptive effect, because LRFCesc and LRFCisq in complete skin of horses did not increase during 24h evaluation. Thus, crotalphine, morphine, U50-488H and phenylbutazone did not cause relevant antinociceptive effect in horses submitted to thermal stimulation in complete skin.