Abstract |
Somatostatin (SRIF) reduces growth hormone releasing hormone (GRF)-stimulated growth hormone (GH) release from avian and mammalian adenohypophyseal cells. The present studies examined the intracellular mechanisms mediating SRIF inhibition of GRF-stimulated GH release from chicken pituitary cells. Increases (P less than 0.05) in GH release were observed in the presence of (1) GRF; (2) the adenylyl cyclase stimulator, forskolin; (3) a cAMP analog, 8-bromo-cAMP; (4) the phosphodiesterase inhibitor 3-isobutyl-l-methyl-xanthine ( IBMX) combined with GRF; (5) a tumor-promoting phorbol ester and protein kinase C activator, phorbol 12-myristate, 13-acetate (PMA); (6) a diacylglycerol analog, 1,2-dioctanoyl-glycerol ( DiC8); and (7) a calcium ionophore, A23187, alone and in combination with PMA. Somatostatin (10 ng/ml) reduced the release of GH stimulated by GRF, forskolin, and 8-bromo cAMP and the GRF-provoked release of GH in the presence of IBMX (P less than 0.05). Somatostatin, however, did not influence GH release in the presence of the protein kinase C activators, PMA or DiC8, or the calcium ionophore A23187. These data suggest that SRIF inhibits GRF-provoked GH release by reducing the ability of the cAMP-protein kinase A but not of the calcium or protein kinase C intracellular message pathways to stimulate GH release.
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Authors | D J Donoghue, C G Scanes |
Journal | General and comparative endocrinology
(Gen Comp Endocrinol)
Vol. 81
Issue 1
Pg. 113-9
(Jan 1991)
ISSN: 0016-6480 [Print] United States |
PMID | 1709126
(Publication Type: Journal Article, Research Support, Non-U.S. Gov't, Research Support, U.S. Gov't, Non-P.H.S.)
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Chemical References |
- Diglycerides
- Phorbol Esters
- 1,2-dioctanoylglycerol
- Somatostatin
- Growth Hormone
- Growth Hormone-Releasing Hormone
- Cyclic AMP
- Protein Kinases
- Adenylyl Cyclases
- 1-Methyl-3-isobutylxanthine
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Topics |
- 1-Methyl-3-isobutylxanthine
(pharmacology)
- Adenylyl Cyclases
(metabolism)
- Animals
- Cells, Cultured
- Chickens
(physiology)
- Cyclic AMP
(analogs & derivatives)
- Diglycerides
(pharmacology)
- Growth Hormone
(metabolism)
- Growth Hormone-Releasing Hormone
(pharmacology)
- Male
- Phorbol Esters
(pharmacology)
- Pituitary Gland, Anterior
(drug effects, physiology)
- Protein Kinases
(metabolism)
- Somatostatin
(pharmacology)
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