Intracellular mechanisms governing the acute phase of beta-endorphin secretion from the corticotrope in vitro.
It is not certain which protein kinase (A, C or both) is involved in the acute phase of beta-endorphin (beta-EP) release stimulated in the corticotrope by vasopressin (VP) and corticotropin-releasing factor (CRF). We have employed an isolated ovine anterior pituitary cell superfusion system to determine the dynamic effects of forskolin, a protein kinase A (PKA) stimulator, and phorbol 12-myristate 13-acetate (PMA), a protein kinase C (PKC) activator. Both secretagogues stimulated beta-EP release within 5 min and therefore both PKA and PKC are potential mediators of the acute phase of hormonal stimulation of the corticotrope. Pretreatment with PMA specifically desensitized the pituitary cell columns to subsequent PMA exposure while not significantly altering sensitivity to forskolin or 50 mM KCl.
Thomson
M
M
Faculty of Medicine, University of Newcastle, N.S.W., Australia.
Chan
E C
EC
Davies
J
J
Falconer
J
J
Madsen
G
G
Geraghty
S
S
Smith
R
R
D000818:Animals; D005576:Colforsin / Q000494:pharmacology; D004723:Endorphins / Q000378:metabolism*; D066298:In Vitro Techniques; D010903:Pituitary Gland, Anterior / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D011494:Protein Kinases / Q000502:physiology*; D015290:Second Messenger Systems; D012756:Sheep; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology
D004723:Endorphins; D005576:Colforsin; D011494:Protein Kinases; D013755:Tetradecanoylphorbol Acetate