Concentration of mRNA encoding 3 beta-hydroxysteroid dehydrogenase/delta 5,delta 4 isomerase (3 beta-HSD) and 3 beta-HSD enzyme activity following treatment of ewes with prostaglandin F2 alpha.
The objectives of these experiments were (1) to determine if prostaglandin F2 alpha (PGF2 alpha) decreased mRNA encoding 3 beta-hydroxysteroid dehydrogenase/d5,delta 4 isomerase (3 beta-HSD) specifically in large steroidogenic luteal cells, which contain the high affinity receptors for PGF2 alpha; and (2) to determine if the decreased concentration of mRNA encoding 3 beta-HSD following administration of PGF2 alpha was associated with a decrease in 3 beta-HSD enzyme activity. Ewes on days 11 or 12 of the estrous cycle were administered PGF2 alpha (25 mg i.v. followed by 10 mg i.m. 2 h later) and corpora lutea collected 4, 12, 24, or 48 h later (n = 4-5/time). Corpora lutea were also collected from non-injected (n = 4) or saline-injected (n = 4) control ewes. Administration of PGF2 decreased (P < 0.05) steady-state concentrations of mRNA encoding 3 beta-HSD to 35, 15, 9, and 5 percent of the concentrations in the control group at 4, 12, 24, and 48 h, respectively. Concentrations of mRNA encoding 3 beta-HSD in large luteal cells were decreased to 43% of controls 4 h following injection, which was similar to the decrease seen in steady-state concentrations of this mRNA in total luteal mRNA (35%). However, 3 beta-HSD enzyme activity was not significantly decreased by 48 h after PGF2 alpha injection. Thus, the dramatic decreased in mRNA encoding 3 beta-HSD was not associated with an immediate decrease in 3 beta-HSD enzyme activity and, therefore, does not appear to be responsible for the acute decrease in secretion of progesterone from ovine luteal tissue during PGF2 alpha-induced luteolysis.
Juengel
J L
JL
Department of Physiology, Colorado State University, Fort Collins 80523, USA.
Meberg
B M
BM
McIntush
E W
EW
Smith
M F
MF
Niswender
G D
GD
D000818:Animals; D003338:Corpus Luteum / Q000378:metabolism; D018076:DNA, Complementary / Q000737:chemistry; D015237:Dinoprost / Q000494:pharmacology*; D005260:Female; D006801:Humans; D007700:Kinetics; D009097:Multienzyme Complexes / Q000235:genetics* / Q000378:metabolism*; D011374:Progesterone / Q000097:blood / Q000378:metabolism; D011375:Progesterone Reductase / Q000235:genetics* / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism*; D017385:Sequence Homology; D012756:Sheep / Q000378:metabolism*; D013251:Steroid Isomerases / Q000235:genetics* / Q000378:metabolism*
C021425:3 beta-hydroxysteroid oxidoreductase-delta(5) 3-ketosteroid isomerase; D018076:DNA, Complementary; D009097:Multienzyme Complexes; D012333:RNA, Messenger; D011374:Progesterone; D015237:Dinoprost; D011375:Progesterone Reductase; D013251:Steroid Isomerases