Progesterone together with estradiol promotes luteinizing hormone beta-subunit mRNA stability in rat pituitary cells cultured in vitro.
The present study examined the role of ovarian steroids, estradiol and/or progesterone in the regulation of luteinizing hormone beta-subunit (LH-beta) mRNA levels and LH release in the rat anterior pituitary cells cultured in vitro. When estradiol (10 nmol/l) and/or progesterone (100 nmol/l) were added to the cultures, neither estradiol or progesterone nor both together altered the basal LH-beta mRNA levels or LH release. Continuous exposure to gonadotropin-releasing hormone (GnRH, 0.2 nmol/l) for 24 h markedly induced LH-beta mRNA accumulation, and in this experimental condition, progesterone alone and progesterone + estradiol further augmented GnRH-induced LH-beta mRNA levels and LH release. Then we explored further the possibility that ovarian steroids are involved in modulating LH-beta mRNA stability in cultured rat pituitary cells where transcription was inhibited by actinomycin D. Anterior pituitary cells were preincubated with GnRH (0.2 nmol/l) for 16 h and, after removing GnRH from culture medium, the cells were incubated further in the presence of actinomycin D (5 mumol/l) for 24 h. The LH-beta mRNA levels gradually declined to about 30% of the control values (zero time point after GnRH removal) in a time-dependent manner. During this period, either progesterone alone or progesterone + estradiol clearly blocked the degradation of LH-beta mRNA species. These results indicate that ovarian steroids promote LH-beta mRNA stability, thereby contributing to the maintenance of GnRH-stimulated LH-beta mRNA levels.
Park
D
D
Department of Pharmacology, College of Medicine, Yonsei University, Seoul, Korea.
Cheon
M
M
Kim
C
C
Kim
K
K
Ryu
K
K
D000818:Animals; D002478:Cells, Cultured; D003470:Culture Media; D003609:Dactinomycin / Q000494:pharmacology; D004355:Drug Stability; D004958:Estradiol / Q000494:pharmacology*; D005260:Female; D007987:Gonadotropin-Releasing Hormone / Q000494:pharmacology; D007986:Luteinizing Hormone / Q000235:genetics*; D010902:Pituitary Gland / Q000187:drug effects / Q000378:metabolism*; D011374:Progesterone / Q000494:pharmacology*; D011500:Protein Synthesis Inhibitors / Q000494:pharmacology; D012333:RNA, Messenger / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley
D003470:Culture Media; D011500:Protein Synthesis Inhibitors; D012333:RNA, Messenger; D003609:Dactinomycin; D007987:Gonadotropin-Releasing Hormone; D011374:Progesterone; D004958:Estradiol; D007986:Luteinizing Hormone