Expression of oxytocin receptors is greatly reduced in the placenta of heavy mares with retained fetal membranes due to secondary uterine atony.

The research investigates the difference in expression of oxytocin receptors in the placentas of heavy mares that retain fetal membranes due to uterine atony. The findings suggest that a drastically reduced level of these receptors might contribute to the onset of uterine atony and subsequent retention of fetal membranes in these animals.

Objective and Research Questions

• The researchers aimed to examine if there is a difference in the expression of oxytocin receptors in the placental tissues of heavy mares depending on whether they expel or retain fetal membranes due to uterine atony.
• The team sought to challenge the conventional treatment approach founded on the assumption that fetal membrane retention is primarily caused by secondary uterine atony and attempted to find more details about the underlying factors.

Methods

• The research drew on a controlled study setup using archived placental tissues. These tissues, composed of the endometrium and allantochorion, were sourced from 8 heavy draught mares during childbirth.
• Four of these mares were able to expel fetal membranes shortly following delivery, and these were classified as control mares. The other four mares retained the fetal membranes for more than 3 hours after delivery due to secondary uterine atony.
• The quantity of oxytocin receptors was estimated by gauging the intensity of western blot bands, a laboratory technique used to detect specific protein molecules in a sample. The location and presence of oxytocin receptors were ascertained through immunocytochemistry, a method used to visualize cellular components.

Results

• The expression of oxytocin receptors was observed to be nearly 50 times less intense in the mares exhibiting placental retention due to secondary uterine atony. The immunocytochemical staining, used to highlight the presence and location of the receptors, was almost invisible.
• In the control mares, which expelled the fetal membranes, the oxytocin receptors were located in both the epithelial and endothelial cells of the placenta. The staining indicating these receptors was most intense at the junction between the endometrium and the allantochorion.

Conclusion

• The findings provided a strong suggestion that inadequate expression of oxytocin receptors could be a contributing factor in the onset of uterine atony, ultimately leading to the retention of fetal membranes in mares.
• This new insight could be instrumental in interpreting the incidence of fetal membrane retention in heavy mares and potentially pave the way for more effective treatment options.