EFFECTS OF GRF(1–40) AND DOMPERIDONE ON GH SECRETION IN NORMAL MAN

Abstract

In 8 normal adult men pituitary secretion following GRF [growth hormone releasing factor] (1-40) was studied. GRF administration (50 .mu.g i.v.) was followed by an increase in GH [growth hormone] release with a peak value between the 15 and 60 min. No effects were noticed on LH [luteinizing hormone], FSH, PRL [prolactin], TSH and ACTH secretion. GH and PRL release was also studied after domperidone (DOM) (5 mg i.v./h), and GRF plus DOM. PRL increased significantly after DOM and GRF plus DOM. During GRF plus DOM a more marked GH release was observed in comparison with the hormone response to GF alone at 15-45 and 120 min (P < 0.05). This phenomenon was found in 6 out of 8 subjects studied. Mean peak and secretory area was greater (P < 0.05) after GRF plus DOM than after GRF alone. GRF (1-40) at the dose used is a useful tool in the study of GH secretion. The GH pattern during GRF plus DOM seems to indicate that dopaminergic tone may play a direct inhibitory role on GH secretion in man.