Cyclic adenosine-3',5'-monophosphate stimulates mouse placental lactogen-I (mPL-I) secretion but inhibits mPL-II secretion at midpregnancy.
To determine whether cAMP regulates mouse placental lactogen-I (mPL-I) and mPL-II secretion at midpregnancy in vitro, mouse placental tissue from day 9 of pregnancy was dispersed with collagenase, cells were fractionated on a Percoll gradient, and the purified trophoblast cells were plated in a serum-free medium. The cells were then incubated with various agents that increased the intracellular cAMP level for 5 days. 8-Bromo-cAMP stimulated mPL-I secretion, but inhibited mPL-II secretion in a time- and dose-dependent manner without changing the amount of newly synthesized trichloroacetic acid-precipitable proteins. Cholera toxin and forskolin, which increase intracellular cAMP accumulation, also regulated mPL-I and mPL-II secretion in the same manner. 8-Bromo-cAMP increased the intracellular mPL-I concentration, decreased the intracellular mPL-II concentration, and increased the immunoprecipitable newly synthesized mPL-I concentration in both the medium and cells. 8-Bromo-cAMP increased the expression of mPL-I messenger RNA and decreased the expression of mPL-II messenger RNA. The sequential reverse hemolytic plaque assay and double immunocytochemistry indicated that 8-bromo-cAMP regulates the subpopulation of giant cells containing and releasing mPL. These findings suggest that an increase in intracellular cAMP stimulates mPL-I secretion, but inhibits mPL-II secretion by changing the subpopulation of giant cells containing and releasing mPL.
Yamaguchi
M
M
Department of Obstetrics and Gynecology, Osaka University Medical School, Japan.
Imai
T
T
Maeda
T
T
Sakata
M
M
Miyake
A
A
D015124:8-Bromo Cyclic Adenosine Monophosphate / Q000494:pharmacology; D000818:Animals; D002454:Cell Differentiation / Q000187:drug effects; D000242:Cyclic AMP / Q000494:pharmacology*; D005260:Female; D015870:Gene Expression / Q000187:drug effects; D007163:Immunosorbent Techniques; D007700:Kinetics; D051379:Mice; D008813:Mice, Inbred ICR; D010928:Placental Lactogen / Q000235:genetics / Q000378:metabolism*; D011247:Pregnancy; D011270:Pregnancy, Animal / Q000502:physiology*; D014176:Protein Biosynthesis
C062303:placental lactogen II; C085699:placental lactogen I, rat; D015124:8-Bromo Cyclic Adenosine Monophosphate; D010928:Placental Lactogen; D000242:Cyclic AMP