Periovulatory changes in the expression of inhibin alpha-, beta A-, and beta B-subunits in hormonally induced immature female rats.
Immature female rats were treated with PMSG and human CG to induce ovulation. Sequential treatment with these hormones allowed us to investigate variations in the production of inhibin subunits shortly before ovulation and during the induced luteal phase. Using this model, we found that expression patterns for the alpha-, beta A-, and beta B-subunits were similar to those observed in mature cycling animals: administration of PMSG (to mimic the gonadotropin surge) led to a sharp increase in the expression of all three subunits in large preovulatory follicles whereas injection with human CG (to induce ovulation) caused a decrease in the levels of the respective mRNAs. In contrast to mature females, shortly before ovulation, levels of inhibin alpha-subunit mRNA were low in small antral follicles (approximately 350 microns). In addition, at that time, inhibin beta A- and beta B-subunits mRNAs were present in several large follicles (greater than 500 microns). More than 2 days after ovulation, inhibin beta A- and beta B-subunit mRNAs could not be detected in small antral size follicles (approximately 350 microns) of hormonally induced females. On the other hand, hybridization signals for the inhibin alpha-subunit were observed in some small antral and preantral size follicles, while signals were very low or undetectable in a large number of atretic follicles. Using this synchronized ovulation model, hybridization patterns for inhibin beta A-subunit mRNA was observed in interstitial cells, 8-10 h after ovulation.(ABSTRACT TRUNCATED AT 250 WORDS)
Meunier
H
H
Division of Endocrinology, Hospital for Sick Children, Toronto, Ontario, Canada.
Roberts
V J
VJ
Sawchenko
P E
PE
Cajander
S B
SB
Hsueh
A J
AJ
Vale
W
W
D000818:Animals; D006063:Chorionic Gonadotropin / Q000494:pharmacology; D005260:Female; D015870:Gene Expression; D006062:Gonadotropins / Q000494:pharmacology*; D006064:Gonadotropins, Equine / Q000494:pharmacology; D007265:Inhibins / Q000235:genetics*; D008183:Luteal Phase; D008954:Models, Biological; D006080:Ovarian Follicle / Q000187:drug effects / Q000378:metabolism*; D010060:Ovulation; D011487:Protein Conformation; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats
D006063:Chorionic Gonadotropin; D006062:Gonadotropins; D006064:Gonadotropins, Equine; D012333:RNA, Messenger; D007265:Inhibins