Endometrial angiogenesis induced by uterine insufflation with an oxygen-ozone gas mixture in mares.

Abstract

Ozone (O3 ) therapy has been used to improve peripheral tissue oxygenation in humans and domestic animals. The goal of the present study was to characterize the histological changes in the endometria of healthy equine following tissue exposure to gas mixtures enriched with different concentrations of O3 . Cycling mares without endometrial degeneration were divided into three groups according to treatment (n=9 mares/group). The uteri from the O3 , ½O3 , and control groups were insufflated for 3 min with gas containing 42, 21, and 0 μg O3 mL-1 , respectively. Treatments were performed every three days from D0 to D6. Endometrial samples were collected immediately before the first treatment and 24 h after the last treatment. The following nine histological parameters were evaluated: i) number of endometrial blood vessels, ii) endometrial vascular degree (EVD), iii) increase rate of blood vessels, iv) increase rate of EVD, v) glandular total area, vi) glandular lumen area, vii) intraglandular secretion area, viii) glandular epithelial height, and ix) luminal epithelial height. In the O3 group, a positive effect from treatment (P < 0.01) was detected for all vascular parameters (i, ii, iii, and iv), glandular total area, intraglandular secretion area, and glandular epithelial height. Compared to the control group, the ½O3 group had greater (P < 0.01) EVD (84.1 ± 12%) and a higher increase rate of blood vessels (151.9±47.1%). Uterine insufflation with low or intermediate concentrations of the O2 -O3 gas mixture induced endometrial angiogenesis. Morphometry, but not morphology, of the endometrial glands was affected by local O3 therapy. These findings would be of great significance for the development of new therapies for infertility in mares.