EFFECT OF DOPAMINE INFUSION ON PLASMA LEVELS OF GROWTH HORMONE IN NONMAL SUBJECTS AND IN AGROMEGALIC PATIENTS

Abstract

In 10 normal subjects and in 20 acromegalic patients plasma levels of growth hormone were studied after administration of L-dopa and a dopamine infusion. In the 10 normal subjects L-dopa, but not dopamine, increased plasma levels of GH [growth hormone]. In the acromegalic patients both L-dopa and dopamine were followed by an inhibition of GH release. Since dopamine does not cross the blood-brain barrier, these results, although not excluding a site of action at median eminence level, support the thesis that the inhibitory effect of dopaminergic stimulation on GH release in acromegaly possibly involves receptors present on GH-secreting cells.