Document Detail

Protein kinase C inhibits TRH-stimulated phosphoinositide hydrolysis in GH3 cells.
MedLine Citation:
PMID:  3032661     Owner:  NLM     Status:  MEDLINE    
The GH3 pituitary tumor line expresses TRH receptors that stimulate phosphoinositide hydrolysis and hormone secretion. After protein kinase C was identified in GH3 cells by direct labeling with [3H]phorbol dibutyrate (PDB), the response to phorbol ester and TRH pretreatment on subsequent TRH-stimulated inositol phosphate (IP) accumulation was found to be inhibitory. Both phorbol myristate acetate (PMA) and PDB were effective in this regard at low nM concentrations within a few minutes, whereas phorbols that do not stimulate protein kinase C were without effect. Furthermore, the mono-, bis- and tris-phosphate forms of IP were all reduced by an average of 30-40% after 5 min of PMA. TRH concentration-response studies indicated a clear change in TRH efficacy induced by PMA. Finally, preincubation with TRH itself was also capable of reducing the subsequent response to TRH. Because TRH receptor action is thought to activate protein kinase C by producing diacylglycerol, these data indicate a negative feedback system via protein kinase C operative during continuous exposure to TRH in GH3 cells.
M Sortino; P L Canonico; S T Summers; M J Cronin
Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  European journal of pharmacology     Volume:  135     ISSN:  0014-2999     ISO Abbreviation:  Eur. J. Pharmacol.     Publication Date:  1987 Mar 
Date Detail:
Created Date:  1987-06-15     Completed Date:  1987-06-15     Revised Date:  2007-11-15    
Medline Journal Info:
Nlm Unique ID:  1254354     Medline TA:  Eur J Pharmacol     Country:  NETHERLANDS    
Other Details:
Languages:  eng     Pagination:  77-83     Citation Subset:  IM    
Export Citation:
APA/MLA Format     Download EndNote     Download BibTex
MeSH Terms
Carcinogens / pharmacology
Cells, Cultured
Lithium / pharmacology
Phorbol 12,13-Dibutyrate
Phorbol Esters / pharmacology
Phosphatidylinositols / metabolism*
Pituitary Neoplasms / metabolism*
Protein Kinase C / pharmacology*
Thyrotropin-Releasing Hormone / antagonists & inhibitors*
Grant Support
Reg. No./Substance:
0/Carcinogens; 0/Phorbol Esters; 0/Phosphatidylinositols; 24305-27-9/Thyrotropin-Releasing Hormone; 37558-16-0/Phorbol 12,13-Dibutyrate; 7439-93-2/Lithium; EC Kinase C

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

Previous Document:  Comparison of GABA-induced responses in various segments of the guinea-pig intestine.
Next Document:  Photoaffinity labeling of a novel benzodiazepine binding protein in rat brain.