Effect of dihydroergocryptine and dihydroergocristine on cyclic AMP accumulation and prolactin release in vitro: evidence for a dopaminomimetic action.

Dihydroergocryptine and dihydroergocristine, two C-9, 10-hydrogenated ergot alkaloids, inhibited in a concentration-dependent manner prolactin release and cyclic AMP accumulation in cultured anterior pituitary cells. The inhibitory effect of dihydroergocryptine was more potent and started at lower concentrations than that of dihydroergocristine. Haloperidol and pimozide, two dopamine receptor antagonists, completely abolished the inhibitory activity of the ergot alkaloids. The involvement of the adenylate cyclase-cyclic AMP system in the inhibitory action of the two compounds was demonstrated by the antagonism by pertussis toxin of the reduction of both prolactin release and cyclic AMP accumulation produced by dihydroergocryptine and dihydroergocristine.