RESUMO
In view of the extensive use of Pterodon species in Brazilian folk medicine, the present investigation was performed to examine the involvement of biogenic amines in antinociceptive by a vouacapan (6 alpha-7 beta-dihydroxy vouacapan-17 beta-oate), extracted from seeds of Pterodon polygalaeflorus Benth), using acetic acid writhing test in mice. The alpha 2-adrenergic (yohimbine) and D2-dopaminergic (domperidone) antagonists and the pretreatment with the peripheral noradrenergic depletor, guanethidine partially inhibited the antinociceptive effect of vouacapan. Dopamine and D2 dopaminergic agonist (Ly 17155) caused antinociceptive that was not antagonized by naloxone but by domperidone, whereas noradrenaline induce pain. A synergistic analgesic effect was obtained when vouacapan was associated with clonidine or dopamine. These results indicate that vouacapan acts, at least in part, through activation of the catecholaminergic system.
Assuntos
Analgésicos não Narcóticos/farmacologia , Diterpenos/farmacologia , Dopamina/fisiologia , Plantas Medicinais , Animais , Brasil , Clonidina/farmacologia , Domperidona/farmacologia , Guanetidina/farmacologia , Masculino , Camundongos , Extratos Vegetais/farmacologia , Ioimbina/farmacologiaRESUMO
The involvement of opioid peptides in the mechanism of action of vouacapan, a new experimental compound extracted from seeds of Pterodon poligalaeflorus Benth, was investigated both in mice utilizing acetic acid writhing response and in rats utilizing inflammatory hyperalgesia induced by carrageenan and modified Randall-Selitto method. Vouacapan, in both models, caused a dose-dependent analgesia when injected p.o., s.c. and i.p. The analgesic effect was partially blocked by naloxone, nalorphine and n-methyl-nalorphine. Significant tolerance to analgesic effect was observed following repeated administration of vouacapan or morphine. On the last day of treatment, cross administration revealed symmetrical and asymmetrical cross-tolerance between vouacapan and morphine, in rats and mice, respectively. We conclude that a release of endorphins could be involved in the analgesic mechanism of vouacapan in both models tudied.