Endometrial explant culture for characterizing equine endometritis.

PROBLEM: Endometritis after insemination is ubiquitous in the horse and is associated with semen and/or bacteria in the uterus. In up to 40% of horses, inflammation persists causing infertility. An endometrial explant culture was developed to study uterine secretion of prostaglandin F(2alpha) (PGF(2alpha)) in response to physiological and pathological challenge.

METHOD OF STUDY: Uteri were collected from mares, the endometrium dissected and explants from the uterine body or horn cultured in William's or RPMI medium. The response of explants to oxytocin, semen or bacteria compared to untreated tissue was tested by collecting medium after 24 and 72 hr and measuring PGF(2alpha) by radioimmunoassay.

RESULTS: Explants from the uterine horn and cultured in William's medium secreted the most PGF(2alpha) after challenge with oxytocin. Explants treated with semen produced a PGF(2alpha) response after 72 hr. Explants collected from mares in the transition season treated with killed S. zooepidemicus or E. coli lipopolysaccharide (LPS) secreted increased concentrations of PGF(2alpha) after 24 and 72 hr. The response to LPS was inhibited by polymyxin B. Follicular and luteal phase explants did not respond to treatments.

CONCLUSIONS: An endometrial explant culture was developed that measured PGF(2alpha) and may be used to study endometritis.