Role of calcium on TPA-induced secretion of ACTH and PGE2 by pituitary cells: effect of dexamethasone.
In pituitary cells in primary culture, ACTH and PGE2 secretions can be simultaneously stimulated by TPA, in the presence of Ca2+. However, whilst PGE2 secretion is under an absolute requirement for Ca2+, ACTH secretion is not. Both secretions are inhibited by dexamethasone but to various extents: PGE2 release is abolished in the presence of dexamethasone whilst only 35% of the TPA-induced ACTH release is sensitive to dexamethasone. Similar inhibitory effects are observed with mepacrine, a PLA2-inhibitor, suggesting that PLA2-activation could be related to these secretory process. Since PLA2-inhibition by dexamethasone is claimed to be mediated via lipocortin, these results suggest that a lipocortin-like protein is present in pituitary cells and could be involved in the TPA-induced secretions of PGE2 and ACTH.
D000324:Adrenocorticotropic Hormone / Q000378:metabolism*; D000818:Animals; D000001:Calcimycin / Q000494:pharmacology; D002118:Calcium / Q000494:pharmacology*; D003907:Dexamethasone / Q000494:pharmacology*; D015232:Dinoprostone; D004305:Dose-Response Relationship, Drug; D008297:Male; D010704:Phorbols / Q000494:pharmacology*; D010741:Phospholipases A / Q000378:metabolism; D054467:Phospholipases A2; D010903:Pituitary Gland, Anterior / Q000187:drug effects / Q000378:metabolism*; D011458:Prostaglandins E / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology*
D010704:Phorbols; D011458:Prostaglandins E; D000001:Calcimycin; D003907:Dexamethasone; D000324:Adrenocorticotropic Hormone; D010741:Phospholipases A; D054467:Phospholipases A2; D015232:Dinoprostone; D013755:Tetradecanoylphorbol Acetate; D002118:Calcium