Growth hormone and prolactin release in acromegalic patients following metergoline administration

In six acromegalite patients oral administration of 4 mg of metergoline, an antiserotonin agent, produced a fall in plasma growth hormone (GH) and prolactin (PRL) concentrations. In the same patients this inhibitory effect was observed after administration of dopaminergic drugs, L-Dopa and 2-Br-alpha-ergocryptine. Both GH and PRL levels remained suppressed during a 6 day course of treatmnt with metergoline. These results are consistent with the hypothesis that the inhibitory effect of netergoline on GH and PRL release is determined by inactivation of serotonin receptors in the hypothalamus or at the pituitary.