Follicle-stimulating Hormone Induced In Vitro Growth of Small Antral Follicles are not Affected by Gonadotropin-releasing Hormone Agonist or Antagonist Treatment in Mice

Abstract

Objective: In this study, we aimed to investigate if the gonadotropin-releasing hormone (GnRH) agonist and antagonist have any effect on the follicle-stimulatinghormone (FSH)-induced-growth of early antral follicles of mice, cultured in vitro, and expressing cognate receptors for FSH and GnRH. For this purpose, small antralfollicles were isolated from mouse ovaries and randomly assigned to the groups as control, FSH only, FSH + GnRH agonist, and FSH + GnRH antagonist, and they werecultured for five days.Methods: The ovaries of C57BL/6 mice (n=24), which were 21 days old, were removed after euthanasia. Small antral follicles measuring ~200μ in diameter weremechanically isolated after the enzymatic digestion of the ovaries with collagenase and DNase-I. The expression of FSH and GnRH receptors in these follicles wasvalidated by quantitative real time-polymerase chain reaction. Isolated follicles were randomly assigned into four different groups, each consisting of 20-30 follicles:control, FSH only, FSH + GnRH agonist, and FSH + GnRH antagonist.Results: The FSH treatment significantly enhanced the in vitro growth of the follicles compared to those cultured without FSH after five days of the culture period. Theantrum formation was markedly enhanced, and cumulus-oophorus complexes were more easily visible in the FSH-treated follicles compared to control follicles. Themean diameters of follicles treated with the FSH + GnRH agonist or the FSH + GnRH antagonist were not significantly different from those treated with FSH only, butthey were significantly greater than control follicles.Conclusion: These results may suggest that the GnRH agonist and antagonist do not appear to adversely affect the FSH-induced proliferation of mitotic non-luteinizinggranulosa cells and the growth of early antral follicles of mice in vitro.