In vivo and in vitro effects of cholecystokinin octapeptide on the release of prolactin in rats.
The effect of cholecystokinin octapeptide (CCK-8) on the release of prolactin (PRL) in rats was studied in vivo and in vitro. Intravenous injection of 5 micrograms/100 g BW of CCK-8 resulted in significant increase in the plasma PRL level after 10 and 20 min. CCK-8 at concentrations of 10(-11) M to 10(-7) M also caused dose-dependent stimulation of PRL release from dispersed cells of rat anterior pituitary. On the other hand, dopamine inhibited PRL release from dispersed cells of rat anterior pituitary in a dose-related manner at concentrations of 10(-8) M to 10(-6) M. Release of PRL from the cells was increased by addition of K+ at high concentration (53 mM) in a Ca++-dependent manner. Addition of 10(-3) M verapamil to the incubation medium inhibited CCK-8-induced PRL release from the cells. Addition of dopamine (10(-7) M) to the incubation medium inhibited PRL release from the cells induced by CCK-8 or high K+ (53 mM). These results indicate that CCK-8 acts directly on the anterior pituitary cells to stimulate PRL release and that calcium ion is involved in the mechanism of this effect.
D000818:Animals; D002118:Calcium / Q000502:physiology; D002478:Cells, Cultured; D004298:Dopamine / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D008297:Male; D010903:Pituitary Gland, Anterior / Q000378:metabolism*; D011188:Potassium / Q000494:pharmacology; D011388:Prolactin / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains; D012636:Secretory Rate / Q000187:drug effects; D012844:Sincalide / Q000494:pharmacology*; D014700:Verapamil / Q000494:pharmacology
D011388:Prolactin; D014700:Verapamil; D012844:Sincalide; D011188:Potassium; D002118:Calcium; D004298:Dopamine