Pharmacological effects of BAM-1120, a novel ergoline derivative, on central dopaminergic functions in rats

BAM-1120, an ergoline derivative, has been found to display a relatively high affinity for dopamine D2-like receptor subtypes in a preliminary binding study. This study investigated whether BAM-1120 acts as a dopamine receptor agonist on prolactin-secreting and motor functions. BAM-1120 suppressed hyperprolactinemia induced by pretreatment with reserpine or estradiol in female rats. Furthermore, BAM-1120 was able to shrink a prolactin-secreting pituitary tumor (prolactinoma) in the estradiol-treated female rats. BAM-1120 induced rotations contralateral to the lesion side in rats with unilateral 6-hydroxydopamine-induced lesions of nigrostriatal dopamine pathway at a dose that was at least 30-fold higher than that required for the inhibition of prolactin secretion. These findings suggest that BAM-1120 is characterized as a putative dopamine D2-like receptor agonist that possesses a preference of inhibiting prolactin secretion over activating motor behaviors.