Modulation of mouse placental lactogen-I secretion in vitro: effects of progesterone and mouse placental lactogen-II.
The primary objective of this study was to develop a cell culture system for assessing effects of putative secretagogues on mouse PL-I (mPL-I) secretion. Trophoblast from days 7 to 11 of pregnancy was dispersed in collagenase, and the cells were fractionated on a Percoll gradient and plated on collagen gels in serum-free medium. Cells from days 7-9 of pregnancy yielded five bands on Percoll gradients and those from days 10 and 11 yielded six. mPL-I was present in four of the bands of cells from each day of pregnancy. Cells from day 7 of pregnancy that banded at a density of 1.044 g/ml secreted the largest amount of mPL-I during 5 days of culture. The mPL-I concentration of the medium of these cells increased for the first 3 or 4 days of culture and then declined on the fifth day. mPL-II could not be detected in the medium until the third or fourth day of culture, and its concentration increased thereafter. Cell viability was about 90% at the time of plating, remained at about 80% between days 1 and 4, and then declined on day 5. The cell type that produced mPL-I was identified with the reverse hemolytic plaque assay and by staining with anti-mPL-I antiserum. Both methods indicated that mPL-I was produced by giant cells. The ability of the cells to respond to putative secretagogues was examined using mPL-II and progesterone. mPL-II, at concentrations ranging between 10 ng/ml and 10 micrograms/ml, had no effect on the mPL-I concentration of the medium when it was present for up to 3 days of culture, which suggests that mPL-II does not inhibit mPL-I secretion in vitro. Incubation of the cells in the presence of 100-1000 ng/ml progesterone caused a dose- and time-dependent reduction in the mPL-I concentration of the medium and a decrease in the number of cells that stained with anti-mPL-I antiserum. The effect of progesterone on both endpoints was not apparent until the second day of treatment. These data suggest that progesterone inhibits mPL-I secretion at least in part by inhibiting the differentiation of mPL-I-producing giant cells. The fact that the mPL-I-producing cells responded to progesterone indicates that this culture system will be useful in assessing effects of putative secretagogues on mPL-I secretion.
Yamaguchi
M
M
Department of Biology, University of California, Santa Cruz 95064.
Endo
H
H
Thordarson
G
G
Ogren
L
L
Talamantes
F
F
D000818:Animals; D002469:Cell Separation; D002478:Cells, Cultured; D002499:Centrifugation, Density Gradient; D005260:Female; D006462:Hemolytic Plaque Technique; D007150:Immunohistochemistry; D007700:Kinetics; D051379:Mice; D010928:Placental Lactogen / Q000378:metabolism* / Q000494:pharmacology*; D011205:Povidone; D011247:Pregnancy; D011374:Progesterone / Q000494:pharmacology*; D011994:Recombinant Proteins / Q000494:pharmacology; D012822:Silicon Dioxide; D014327:Trophoblasts / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*
D011994:Recombinant Proteins; C062303:placental lactogen II; D011374:Progesterone; C016039:Percoll; D012822:Silicon Dioxide; D010928:Placental Lactogen; D011205:Povidone