Presentation Title

The contribution of growth and differentiation factor 9 (GDF-9) and gonadotropins to the resumption of regressed ovaries to function in vitro

Faculty Mentor

Young KA

Start Date

23-11-2019 10:00 AM

End Date

23-11-2019 10:45 AM

Location

75

Session

poster 3

Type of Presentation

Poster

Subject Area

biological_agricultural_sciences

Abstract

The mechanism responsible for the reinitiation of ovarian function in seasonally-regressed ovaries has not been well explored. In photoperiodic Siberian hamsters, changes in day lengths induce alterations in gonadotropin hormones (GT) and growth factors, which subsequently stimulate or inhibit ovarian function. To identify the individual contributions of these factors to recrudescence, or the return of regressed ovaries to function, photo-regressed ovaries were cultured with and without GT and growth differentiation factor-9 (GDF-9), a key factor in ovarian follicle development. We hypothesized that culturing regressed ovaries with gonadotropins and GDF-9 would enhance restoration of folliculogenesis and production of estradiol. Female Siberian hamsters were exposed to inhibitory photoperiod for 16-weeks to induce ovarian regression. Regressed ovaries were collected and cultured for 14 days in media containing one of four treatments: no treatment control (NT), GT, GDF-9, GT+GDF-9. Plasma estradiol concentrations were low among animals in the NT, GT or GDF-9 groups; however, estradiol increased significantly in the GT+GDF-9 as compared to other groups. To assess ovarian function across the groups, mRNA levels of folliculogenic factors including: luteinizing hormone receptor (Lhr), inhibin-α (Inh-α), cyclooxygenase-2 (Cox-2), and insulin-like growth factor-1 (Igf-1) were measured using real-time PCR. Cox-2 mRNA expression peaked in GT and GT+GDF-9 groups as compared to NT and GDF-9 only groups. Inh-α and Lhr mRNA expression were increased in the GT+GDF-9 group as compared to expression in ovaries in the NT, GT, and GDF-9 groups. No differences were noted across any groups for Igf-1 mRNA expression. Incubating whole ovaries with gonadotropins and GDF-9 increased aspects of folliculogenesis and steroidogenesis as compared to no-treatment controls, even above treatment with either factor alone. However, because not all aspects of ovarian function were restored with treatment, additional factors are clearly needed to restore photoregressed ovaries to full function.

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Nov 23rd, 10:00 AM Nov 23rd, 10:45 AM

The contribution of growth and differentiation factor 9 (GDF-9) and gonadotropins to the resumption of regressed ovaries to function in vitro

75

The mechanism responsible for the reinitiation of ovarian function in seasonally-regressed ovaries has not been well explored. In photoperiodic Siberian hamsters, changes in day lengths induce alterations in gonadotropin hormones (GT) and growth factors, which subsequently stimulate or inhibit ovarian function. To identify the individual contributions of these factors to recrudescence, or the return of regressed ovaries to function, photo-regressed ovaries were cultured with and without GT and growth differentiation factor-9 (GDF-9), a key factor in ovarian follicle development. We hypothesized that culturing regressed ovaries with gonadotropins and GDF-9 would enhance restoration of folliculogenesis and production of estradiol. Female Siberian hamsters were exposed to inhibitory photoperiod for 16-weeks to induce ovarian regression. Regressed ovaries were collected and cultured for 14 days in media containing one of four treatments: no treatment control (NT), GT, GDF-9, GT+GDF-9. Plasma estradiol concentrations were low among animals in the NT, GT or GDF-9 groups; however, estradiol increased significantly in the GT+GDF-9 as compared to other groups. To assess ovarian function across the groups, mRNA levels of folliculogenic factors including: luteinizing hormone receptor (Lhr), inhibin-α (Inh-α), cyclooxygenase-2 (Cox-2), and insulin-like growth factor-1 (Igf-1) were measured using real-time PCR. Cox-2 mRNA expression peaked in GT and GT+GDF-9 groups as compared to NT and GDF-9 only groups. Inh-α and Lhr mRNA expression were increased in the GT+GDF-9 group as compared to expression in ovaries in the NT, GT, and GDF-9 groups. No differences were noted across any groups for Igf-1 mRNA expression. Incubating whole ovaries with gonadotropins and GDF-9 increased aspects of folliculogenesis and steroidogenesis as compared to no-treatment controls, even above treatment with either factor alone. However, because not all aspects of ovarian function were restored with treatment, additional factors are clearly needed to restore photoregressed ovaries to full function.