Periovulatory Changes in the Expression of Inhibin α-, βA-, and βB-Subunits in Hormonally Induced Immature Female Rats

Hélène Meunier, Veronica J. Roberts, Paul E. Sawchenko, Stefan B. Cajander, Aaron J. W. Hsueh, Wylie Vale
1989 Molecular Endocrinology  
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 a-, 0A-, and /SB-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
more » ... f 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 a-subunit mRNA were low_in small antral follicles (~350/im). In addition, at that time, inhibin 0A-and 0B-subunits mRNAs were present in several large follicles (>500 nm). More than 2 days after ovulation, inhibin 0A-and /?B-subunit mRNAs could not be detected in small antral size follices (-350 nm) of hormonally induced females. On the other hand, hybridization signals for the inhibin a-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 £A-subunit mRNA was observed in interstitial cells, 8-10 h after ovulation. These findings suggest that hCG, and presumably LH, may contribute to decrease the production of inhibin subunits in stimulated preovulatory
doi:10.1210/mend-3-12-2062 pmid:2628740 fatcat:gufqx66uhbh2xjog6kk67smw4q