Increasing expression of oxytocin and vasopressin receptors in the equine conceptus between Days 10 and 16 of pregnancy.

This research explores the increasing expression of oxytocin and vasopressin receptors in equine (horse) conceptuses from day 10 to 16 of pregnancy, suggesting the hormones’ potential role in early equine pregnancy.

Research Objectives and Methodology

• The research aimed to establish the presence and increasing expression of receptors to oxytocin (OT) and arginine vasopressin (AVP) in the equine conceptuses during early pregnancy. These hormones have been detected in the yolk sac of pre-attachment equine conceptuses, but the study aims to deeper explore their function and evolution.
• Conceptuses harvested between Day 10 and Day 16 of pregnancy were used in the researchers’ investigation. The detection of the OT and AVP receptors took place via qualitative PCR, quantitative PCR, and immunohistochemistry – methods that allow for the detection and measurement of specific DNA and/or protein segments.

Research Outcomes

• The researchers were able to confirm the presence and increasing expression of OT and the AVP receptors V1aR and V2R in the equine conceptus. Expressed receptor quantities showed a significant increase with pregnancy progression
• Immunohistochemistry revealed changes and different receptor distributions on each day of the investigation. Oxytocin receptor presence was quite weak on Day 10, but noticeable increases were seen by Day 12. From Day 14 through Day 16, some cells showed increasing levels of OTR, while others exhibited reduced levels. The endoderm of the trophoblast and surrounding subtrophoblastic compartments always showed moderate staining for OTR.
• Arginine vasopressin receptor V2R was detected in the apical membrane of the conceptus on Day 10 and expanded to the basal membrane and cytoplasm by Day 12. On Day 14, only individual cells showed positive V2R detection in supranuclear cytoplasmic areas. By Day 16, about a third of the cells showed entire, strong staining for V2R.

Research Significance

• The findings of this research imply that the OT and AVP hormones, through their respective receptors, play a significant part in the development and expansion of the equine conceptus during early pregnancy.
• The dynamic changes in the distribution and intensity of receptor expression, along with increased receptor quantities as pregnancy progresses, suggest a nuanced regulation of these hormones in early pregnancy. Further investigation may help in understanding the exact mechanisms and functions of OT and AVP in pregnancy.