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

Abstract

The effects of administration of equine follicular fluid (FF) on gonadotropin concentrations in the ovariectomized (OVX) mare were examined. The FF was obtained by aspiration of follicles in ovaries obtained during the summer at a slaughterhouse. Systemic administration of whole equine FF to OVX mares resulted in significant decreases in circulating concentrations of FSH (26.0-74.0% of the pretreatment concentrations depending on dosage). Treatment with FF from which steroids had been removed tended (P<0.10) to decrease FSH. Treatment with either a steroid fraction alone or a steroid fraction with denatured proteins had no effect (P>0.10) on FSH. Treatment with whole FF initially decreased and then increased the concentrations of LH. It was concluded that the equine FF contained a nonsteroidal substance that has FSH suppressing properties.