Effect of caerulein on pituitary response to TRH in humans

The effect of caerulein (100 ng/kg/h X 1 h) on basal as well as on thyrotropin-releasing hormone (TRH)-stimulated prolactin and thyroid-stimulating hormone (TSH) secretion was studied in healthy male volunteers. The peptide did not change the basal levels of prolactin and TSH. However, during the infusion of caerulein, prolactin response to TRH was significantly increased whereas the TSH response was decreased. These data, showing an action of caerulein (a frog peptide which mimics the biological actions of cholecystokinin) on prolactin and TSH release, suggest that cholecystokinin may be involved in the physiological control of human pituitary secretion.