Bioactivity of the essential oil from berries of Vitex agnus castus in middle aged male rats

Abstract

Pharmaceutical preparations of Vitex agnus castus L. (VAC) were shown to contain several bioactive compounds, which were capable to interfere with action of specific human hormones, thus exerting putative beneficial therapeutic effects. The goal of this study was to examine the effects of the essential oil from berries of VAC on the motor behavior of male rat, in relation to the possible dopaminergic actions of the active components. Middle-aged male Wistar rats were treated with VAC essential oil for 3 weeks (60 mg/kg/day s.c) and submitted to the open field test. Their brain preparations were used for in vitro binding assays at dopamine receptors and immunohistochemical/morphometric analyses of pituitary lactotrophs. Chronic application of VAC essential oil significantly reduced rat motor activity, although it did not influence in vitro binding parameters at nigrostriatal D-1 and D-2 dopamine receptors. However, the relative volume density of prolactin-immunopositive cells per pituitary unit was significantly decreased by 36%, which reflected down-regulation of their function following the treatment. These findings suggest that the reduction in rat motor activity, registered after chronic administration of VAC essential oil, is probably induced by non-dopaminergic mechanism(s).