Effect of bromocriptine, ergotamine and other ergot alkaloids on the hormone secretion and growth of a rat pituitary tumour

Abstract

The effect of bromocriptine on hormone secretion and the growth of the prolactin- and growth hormone (GH)-secreting rat pituitary tumour of the GH3 cell line has been compared with that of ergotamine and other ergot alkaloids. Bromocriptine in doses ranging from 1 to 20 mg/kg had no effect on tumour growth or on the excessive secretion of GH by the tumour; prolactin concentrations were reduced only by the highest dosage of the drug. Similarly the tumour was resistant to the administration of ergocryptine, ergocornine and the synthetic ergolines, lergotrile and CH 29-717. In contrast, ergotamine reduced secretion of both GH and prolactin and considerably inhibited the growth of the tumour. Experiments in vitro showed that ergotamine inhibited DNA synthesis of the tumour cells and decreased hormone secretion. It was concluded that ergotamine had a direct inhibitory action on the GH3 cell tumour which was not mediated through the dopaminergic mechanisms.