Adenosine 3',5'-monophosphate (cAMP) and calcium-calmodulin interrelation in the control of prolactin secretion: evidence for dopamine inhibition of cAMP accumulation and prolactin release after calcium mobilization.
Calcium (Ca2+) ionophore A23187 increased the intracellular cAMP content and PRL release in normal rat anterior pituitary cells. Cotreatment with dopamine reduced both control and A23187-stimulated cAMP accumulation and PRL release. The dopamine antagonist spiperone restored the response of cAMP to ionophoric stimulation after pretreatment with dopamine in the greatest concentration used. Penfluridol, a compound with Ca2+-calmodulin-blocking properties, decreased control and A23187-stimulated cAMP content and PRL release. W7, a selective calmodulin-blocking agent, reduced basal cAMP and PRL release, whereas W5, a W7 analog with only 20% of its calmodulin-blocking ability, did not affect cAMP or PRL secretion. These data indicate that the Ca2+-calmodulin and cAMP systems are interrelated in the regulation of PRL secretion. They are also consistent with the hypothesis that the inhibition of PRL release by dopamine occurs after Ca2+ is mobilized and when or before it stimulates adenylate cyclase activity.
D000818:Animals; D000001:Calcimycin / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism*; D002135:Calcium-Binding Proteins / Q000378:metabolism*; D002147:Calmodulin / Q000378:metabolism*; D002478:Cells, Cultured; D000242:Cyclic AMP / Q000378:metabolism*; D004298:Dopamine / Q000494:pharmacology*; D007700:Kinetics; D008297:Male; D010395:Penfluridol / Q000494:pharmacology; D010903:Pituitary Gland, Anterior / Q000187:drug effects / Q000378:metabolism / Q000502:physiology*; D011388:Prolactin / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains; D013134:Spiperone / Q000494:pharmacology
D002135:Calcium-Binding Proteins; D002147:Calmodulin; D010395:Penfluridol; D000001:Calcimycin; D013134:Spiperone; D011388:Prolactin; D000242:Cyclic AMP; D002118:Calcium; D004298:Dopamine