Effects of estradiol on uterine perfusion in anesthetized cyclic mares affected with uterine vascular elastosis.

The research focuses on the effects of estradiol on blood flow in the uterus, comparing results between mares with normal vasculature and mares affected by uterine vascular elastosis, a degenerative condition that causes the thickening of blood vessel layers in the uterus.

Uterine Vascular Elastosis

• The condition studied in this research is uterine vascular elastosis, prevalent in mares, where the blood vessels in the uterus degenerate due to thickened elastin layers. Age, the number of pregnancies a mare has experienced (parity), and chronic inflammation in the uterine lining (endometritis) are linked to this degeneration.
• Mares suffering from this condition have been observed to have lower uterine blood flow and perfusion of their uterus. As a result of the thickened elastin, the researchers hypothesize that the ability for blood vessels in the uterus to expand (vasodilation) might also be impaired.

Research Methodology

• To investigate this hypothesis, the researchers tested the vasodilatory effects of the hormone estradiol on two sets of mares, one with healthy blood vessels in the uterus, and the other with severely affected elastosis.
• This process was carried out during both the ovulation (estrus) and non-ovulation (diestrus) period of the mares’ reproductive cycle.
• Initially, fluorescent microspheres were used to ascertain the base level of blood perfusion in the uterus. Then 17β-estradiol was administered intravenously at 1.0 μg/kg dose. The perfusion rate was then measured again 90 min post-dose to check what change, if any, the estradiol had on blood flow.

Research Findings

• Healthy mares displayed a significant increase in total uterine blood flow after receiving the estradiol infusion, but only during the estrus period. No other group demonstrated a significant increase in blood flow and perfusion after the estradiol induction.
• In healthy mares’ case, estradiol was seen to cause area-specific increases in blood flow in the uterine horns and body during estrus and only in the uterine horns during the diestrus.
• In contrast, the mares affected by elastosis displayed no area-specific differences in blood flow rates following the introduction of estradiol.
• This discrepancy in how estradiol influenced the vasodilation process between the healthy mares and those affected by elastosis suggests that the functionality of the blood vessels in the latter group is negatively impacted by the condition.