Changes in concentrations of circulating gonadotropins following administration of equine follicular fluid to ovariectomized mares.

The research investigates the effects of equine follicular fluid (FF) on the levels of gonadotropin hormones in female horses without ovaries. The study found that infusions of whole equine FF led to significant reductions in circulating follicle-stimulating hormone (FSH), suggesting that the equine FF contains a non-steroidal substance suppressing FSH production.

Research Context

• The study aimed to explore the impacts of equine follicular fluid (FF) on gonadotropin hormone concentrations in ovariectomized, or ovary-removed, mares. Essentially, the researchers wanted to see how FF influences hormone levels in horses without ovaries.

Research Method

• Equine FF was collected through aspiration of follicles from ovaries sourced from a slaughterhouse during the summer.
• Systemic administration of whole equine FF was then given to the OVX mares, and subsequent changes in hormone levels were observed and recorded.
• The researchers experimented with different treatments, including FF with steroids removed, a steroid fraction alone, and a steroid fraction combined with denatured proteins.

Major Findings

• Following the systemic administration of whole equine FF, significant decreases in circulating concentrations of follicle-stimulating hormone (FSH) were noted, with reductions ranging between 26.0–74.0% of the pretreatment concentrations, depending on the dosage.
• Even the FF treatment from which steroids had been removed tended towards decreasing FSH, but these results were less significantly so (P<0.10).
• No notable impact on FSH was observed with the treatment involving either a steroid fraction alone or a steroid fraction coupled with denatured proteins (Both with P>0.10).
• Whole FF treatment at first decreased, and then increased, the concentrations of luteinizing hormone (LH).
• Taken together, these findings led to the conclusion that equine FF contains a nonsteroidal substance that demonstrates FSH-suppressing attributes.

Significance of the Study

• The outcomes of this study signify a better understanding of how equine FF can regulate gonadotropin hormones in OVX mares, which could pave the way for more advanced studies and potential applications in veterinary reproductive medicine.