Evidence of the involvement of biogenic amines in the antinociceptive effect of a vouacapan extracted from Pterodon polygalaeflorus Benth

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 antinociception 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 D-2-dopaminergic (domperidone) antagonists and the pretreatment with the peripheral noradrenergic depletor, guanethidine partially inhibited the antinociceptive effect of vouacapan. Dopamine and D-2 dopaminergic agonist (Ly 171555) caused antinociception that was not antagonized by naloxone but by domperidone, whereas noradrenaline induced 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.