Influence of different semen extenders and seminal plasma on PMN migration and on expression of IL-1beta, IL-6, TNF-alpha and COX-2 mRNA in the equine endometrium.

This research article explores how different substances used to preserve sperm (semen extenders) and seminal plasma induce an inflammatory response in the horse’s endometrium after artificial insemination or mating. The study reveals that all treatments increased endometrial inflammatory responses, with egg yolk-based semen extenders causing the least pronounced response.

Materials and Methods

• The research team worked with oestrous mares (females in heat) and introduced different semen extenders: phosphate buffered saline (PBS), seminal plasma (SP), skim milk-based extender (SM), or an egg yolk semen extender (EY) into the uterus.
• This was carried out in four consistent cycles in an alternating sequence.
• Right after 12 hours of each treatment, an endometrial biopsy was obtained, using uterine lavage (a washout) method. An additional biopsy was taken before the beginning of the experiments for comparison purposes.
• The researchers showed no notable changes in the volume, pH, specific density, or cell count of the lavage fluid through the different treatments.

Findings and Results

• The results demonstrated a significantly lower number of leukocytes (white blood cells that fight infections) in the endometrium in the biopsies taken before the experiments (68+/-5 leukocytes per field) when compared to PBS (154+/-32), SP (175+/-22), SM (193+/-29), and EY treatments (113+/-17).
• Meanwhile, the numbers of polymorphonuclear neutrophils (PMN, a type of immune cell) were found to be comparatively lower after the infusion of EY (23+/-10) when compared to PBS (59+/-21) and SM extender (69+/-21).
• The study also observed an increase in the number of eosinophils (a type of disease-fighting white blood cell) after the inoculation of SP.
• All treatments increased the expression of interleukins (IL)-1beta and 6, and tumor necrosis factor-alpha (TNF-alpha) and cyclooxgygenase-2 (COX-2) in the endometrium compared to pre-experiment values.
• Notably, the expression of COX-2 mRNA was significantly higher after the infusion of SM than after PBS treatment.

Conclusion

• In conclusion, all the treatments including different extenders, seminal plasma, and PBS, resulted in an inflammatory endometrial response.
• Out of all treatments, the egg yolk-based semen extender (EY) appeared to provoke the least severe inflammatory response, indicating it may be the more favorable option for artificial insemination in horses.