Estrogen-insulin synergism in induction of prolactin in growth hormone-producing cells.
Insulin suppresses growth hormone expression and induces prolactin (PRL) biosynthesis in MtT/S cells cultured in a medium supplemented with normal sera. Incorporation of [35S]amino acids into immunoprecipitable PRL became detectable at 15 h of culture with insulin (500 ng/ml) and increased up to 48 h. Northern blot hybridization demonstrated a concurrent induction of PRL mRNA. However, insulin failed to induce PRL in a medium supplemented with steroid-depleted sera. Either pre- or cocultivation of cells with 10 pM to 10 nM 17 beta-estradiol (E2), which did not induce PRL by itself, restored the insulin-mediated PRL biosynthesis in a dose-dependent manner. Diethylstilbestrol was as effective as E2, whereas testosterone, progesterone and corticosterone were without effect. The E2 action was partially suppressed by tamoxifen. These results suggest that estrogen is required for the insulin-mediated induction of PRL biosynthesis in MtT/S cells.
Nagata
S
S
Department of Cell Chemistry, Tokyo Metropolitan Institute of Gerontology, Japan.
Inoue
K
K
Senshu
T
T
D000818:Animals; D015152:Blotting, Northern; D015153:Blotting, Western; D002478:Cells, Cultured; D004967:Estrogens / Q000502:physiology*; D013006:Growth Hormone / Q000378:metabolism*; D007328:Insulin / Q000502:physiology*; D010902:Pituitary Gland / Q000166:cytology / Q000378:metabolism*; D011233:Precipitin Tests; D011388:Prolactin / Q000378:metabolism*; D051381:Rats
D004967:Estrogens; D007328:Insulin; D011388:Prolactin; D013006:Growth Hormone