Presumptive mediators of growth hormone action on insulin-like growth factor I release by porcine ovarian granulosa cells.
The role of cAMP/protein kinase A (PKA)- and tyrosine kinase (TK)-dependent intracellular mechanisms in mediating the action of porcine growth hormone (GH) on insulin-like growth factor I (IGF-I) secretion by porcine ovarian granulosa cells was studied. It was observed that GH-induced stimulation of IGF-I secretion was accompanied by an increase in cAMP production. The stimulation of PKA by the addition of either a cAMP agonist or a phosphodiesterase inhibitor to the medium increased IGF-I release by the cells, indicating a direct stimulation of IGF-I release by cyclic nucleotides. Moreover, the stimulatory effect of GH on IGF-I was completely suppressed by the addition of the PKA blocker Rp-cAMPS. Neither TK blocker altered the basal IGF-I level, but both strongly suppressed the GH-induced increase in IGF-I accumulation. Taken together, these findings suggest that cAMP/PKA- and/or TK-dependent pathways may be involved in the mediation of GH action on IGF-I release by porcine granulosa cells.
Makarevich
A V
AV
Research Institute of Animal Production, Nitra, Slovak Republic. makarev@vuzv.sk
Sirotkin
A V
AV
D015056:1-Methyl-3-isobutylxanthine / Q000494:pharmacology; D000818:Animals; D002478:Cells, Cultured; D000242:Cyclic AMP / Q000819:agonists / Q000031:analogs & derivatives* / Q000378:metabolism / Q000494:pharmacology / Q000502:physiology*; D017868:Cyclic AMP-Dependent Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism / Q000502:physiology*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005260:Female; D006107:Granulosa Cells / Q000378:metabolism*; D013006:Growth Hormone / Q000494:pharmacology / Q000502:physiology*; D007334:Insulin-Like Growth Factor I / Q000378:metabolism*; D010726:Phosphodiesterase Inhibitors / Q000494:pharmacology; D011505:Protein-Tyrosine Kinases / Q000037:antagonists & inhibitors / Q000502:physiology*; D013552:Swine; D013873:Thionucleotides / Q000494:pharmacology
D004791:Enzyme Inhibitors; D010726:Phosphodiesterase Inhibitors; D013873:Thionucleotides; C016957:adenosine-3',5'-cyclic phosphorothioate; D007334:Insulin-Like Growth Factor I; D013006:Growth Hormone; D000242:Cyclic AMP; D011505:Protein-Tyrosine Kinases; D017868:Cyclic AMP-Dependent Protein Kinases; D015056:1-Methyl-3-isobutylxanthine