Evidence that phorbol diester-sensitive protein kinase-C(s) may not be directly involved in secretagogue-stimulated prolactin release and arachidonate liberation.
This report presents findings pertaining to the role of protein kinase-Cs in the release of PRL and liberation of arachidonate from PRL-secreting cells. In our experiments, protein kinase-C activators increased PRL release and arachidonate liberation from anterior pituitary cells and from the PRL-secreting cell line MMQ. In cells depleted of pituitary protein kinase-Cs by chronic exposure to protein kinase-C activators, such as phorbol dibutyrate or 4 beta-phorbol 12 beta-myristate 13 alpha-acetate, TRH, angiotensin-II, and neurotensin each increased PRL release and [3H]arachidonate liberation in a normal manner. In addition, the PRL-releasing activities of protein kinase-C activators and those of TRH appeared to be synergistic, an unexpected effect if these substances were functioning through the same intracellular pathways. It, therefore, appears that phorbol diester-sensitive protein kinase-Cs may not be involved in the increased secretion of PRL or liberation of arachidonate that is caused by TRH, angiotensin-II, or neurotensin.
Judd
A M
AM
Department of Internal Medicine, University of Virginia Health Sciences Center, Charlottesville 22908.
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I S
IS
MacLeod
R M
RM
D000804:Angiotensin II / Q000494:pharmacology; D000818:Animals; D016718:Arachidonic Acid; D001095:Arachidonic Acids / Q000378:metabolism*; D002460:Cell Line; D002478:Cells, Cultured; D005260:Female; D007700:Kinetics; D008387:Marine Toxins / Q000494:pharmacology; D009496:Neurotensin / Q000494:pharmacology; D035964:Oxocins; D015240:Phorbol 12,13-Dibutyrate / Q000494:pharmacology*; D010903:Pituitary Gland, Anterior / Q000187:drug effects / Q000378:metabolism*; D011388:Prolactin / Q000378:metabolism*; D011493:Protein Kinase C / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology*; D013973:Thyrotropin-Releasing Hormone / Q000494:pharmacology; D000095702:Polyether Toxins
D000804:Angiotensin II; D016718:Arachidonic Acid; D001095:Arachidonic Acids; D008387:Marine Toxins; D009496:Neurotensin; D035964:Oxocins; D015240:Phorbol 12,13-Dibutyrate; D011388:Prolactin; D011493:Protein Kinase C; D013755:Tetradecanoylphorbol Acetate; D013973:Thyrotropin-Releasing Hormone; C020394:maitotoxin; D000095702:Polyether Toxins