Regulation of mouse placental lactogen secretion by G proteins before midpregnancy.
To determine whether G proteins are involved in the regulation of mouse placental lactogen-I (mPL-I) and/or mPL-II secretion before midpregnancy, mouse placental tissue from day 7 of pregnancy was dispersed with collagenase, cells were fractionated on a percoll gradient, and the purified trophoblast cells were cultured in a serum-free medium with cholera toxin (CTX) or pertussis toxin (PTX) which modulate the activities of distinct G proteins for 5 days. CTX inhibited both mPL-I and mPL-II secretion, but PTX inhibited mPL-I secretion and stimulated mPL-II secretion in a time- and dose-dependent manner. Addition of both CTX and PTX additionally inhibited mPL-I secretion but did not affect mPL-II secretion. 8-Bromo cAMP, which increases intracellular cAMP accumulation, inhibited both mPL-I and mPL-II secretion similarly to CTX. In contrast, H8, an inhibitor of cAMP-dependent protein kinase A, stimulated both mPL-I and mPL-II secretion. Addition of PTX and H8 synergistically stimulated mPL-II secretion. These findings suggest that G proteins play important roles in regulation of mPL-I and mPL-II secretion before midpregnancy.
Department of Obstetrics and Gynecology, Osaka University Medical School, Japan.
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Yamaguchi
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Miyake
D015124:8-Bromo Cyclic Adenosine Monophosphate / Q000494:pharmacology; D000704:Analysis of Variance; D000818:Animals; D002478:Cells, Cultured; D002772:Cholera Toxin / Q000494:pharmacology*; D017868:Cyclic AMP-Dependent Protein Kinases / Q000037:antagonists & inhibitors / Q000502:physiology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005260:Female; D019205:GTP-Binding Protein alpha Subunits, Gs / Q000502:physiology; D019204:GTP-Binding Proteins / Q000502:physiology*; D007546:Isoquinolines / Q000494:pharmacology; D051379:Mice; D008813:Mice, Inbred ICR; D037342:Pertussis Toxin; D010928:Placental Lactogen / Q000378:metabolism*; D011247:Pregnancy; D011270:Pregnancy, Animal / Q000502:physiology*; D012636:Secretory Rate / Q000187:drug effects; D010566:Virulence Factors, Bordetella / Q000494:pharmacology*
D004791:Enzyme Inhibitors; D007546:Isoquinolines; D010566:Virulence Factors, Bordetella; C062303:placental lactogen II; C085699:placental lactogen I, rat; D015124:8-Bromo Cyclic Adenosine Monophosphate; C053177:N-(2-(methylamino)ethyl)-5-isoquinolinesulfonamide; D002772:Cholera Toxin; D010928:Placental Lactogen; D037342:Pertussis Toxin; D017868:Cyclic AMP-Dependent Protein Kinases; D019204:GTP-Binding Proteins; D019205:GTP-Binding Protein alpha Subunits, Gs