Animal Science Department

 

Date of this Version

11-2-2021

Citation

Biology of Reproduction, 2022, 106(1), 118–131 https://doi.org/10.1093/biolre/ioab201

Comments

Used by permission.

Abstract

A population of cows with excess androstenedione (A4; High A4) in follicular fluid, with follicular arrest, granulosa cell dysfunction, and a 17% reduction in calving rate was previously identified. We hypothesized that excess A4 in the ovarian microenvironment caused the follicular arrest in High A4 cows and that vascular endothelial growth factor A would rescue the High A4 phenotype. In trial 1, prior to culture, High A4 ovarian cortex (n=9) had greater numbers of early stage follicles (primordial) and fewer later-stage follicles compared to controls (n=11). Culture for 7 days did not relieve this follicular arrest; instead, High A4 ovarian cortex had increased indicators of inflammation, anti-Mullerian hormone, and A4 secretion compared to controls. In trial 2, we tested if vascular endothelial growth factor A (VEGFA) angiogenic (165) and antiangiogenic (VEGFA165b) isoforms could rescue the High A4 phenotype. High A4 (n=5) and control (n=5) ovarian cortex was cultured with (1) PBS, (2) VEGFA165 (50 ng/mL), (3) VEGFA165b (50 ng/mL), or (4) VEGFA165+VEGFA165b (50 ng/mL each) for 7 days. Follicular progression increased with VEGFA165 in High A4 cows with greater early primary, primary, and secondary follicles than controls. Similar to trial 1, High A4 ovarian cortex secreted greater concentrations of A4 and other steroids and had greater indicators of inflammation compared to controls. However, VEGFA165 rescued steroidogenesis, oxidative stress, and fibrosis. Both VEGFA isoforms reduced specific pro-inflammatory cytokines in High A4 cows to control levels. Thus, VEGFA165 may be a potential therapeutic to restore the ovarian steroidogenic microenvironment to promote folliculogenesis.

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