EVIDENCE OF THE INVOLVEMENT OF BIOGENIC-AMINES IN THE ANTINOCICEPTIVEEFFECT OF A VOUACAPAN EXTRACTED FROM PTERODON-POLYGALAEFLORUS BENTH

In view of the extensive use of Pterodon species in Brazilian folk med icine, the present investigation was performed to examine the involvem ent of biogenic amines in antinociception by a vouacapan (6 alpha-7 be ta-dihydroxy vouacapan-17 beta-oate, extracted from seeds of Pterodon polygalaeflorus Benth), using acetic acid writhing test in mice. The a lpha(2)-adrenergic (yohimbine) and D-2-dopaminergic (domperidone) anta gonists and the pretreatment with the peripheral noradrenergic depleto r, guanethidine partially inhibited the antinociceptive effect of voua capan. Dopamine and D-2 dopaminergic agonist (Ly 171555) caused antino ciception that was not antagonized by naloxone but by domperidone, whe reas noradrenaline induced pain. A synergistic analgesic effect was ob tained when vouacapan was associated with clonidine or dopamine. These results indicate that vouacapan acts, at least in part, through activ ation of the catecholaminergic system.