CCK-8 antagonizes apomorphine-induced growth hormone secretion in normal subjects

Cholecystokinin octapeptide (CCK-8) (5 ug iv over 10 minutes) administered to normal men had no effect on basal growth hormone (GH) or prolactin secretion but significantly antagonized the GH response to the dopamine (DA) receptor agonist, apomorphine HCI (Apo) (0.5 mg sc), 30 (P less than 0.05) and 45 minutes (P less than 0.01) after Apo injection (n = 8). These results are compatible with an inhibitory effect of CCK-8 on certain DA mechanisms in the hypothalamic-pituitary axis. Whether CCK-8 affects DA function in other brain regions in man is unknown.