Equine early pregnancy endocrine profiles and ipsilateral endometrial immune cell, gene expression and protein localisation response.

The research examines how the early-stage equine (horse) embryo influences maternal serum composition, uterine immune response, and genetic and protein factors associated with embryo development and pregnancy maintenance.

Objective of the Research

• This study aimed to understand the changes brought about in maternal hormones, immune cells within the uterus, and genes and proteins related to embryonic development and maintenance of pregnancy by the equine embryo during the early stages of pregnancy.

Methodology

• The maternal serum concentrations of insulin-like growth factor 1 (IGF1), leptin, and adiponectin were studied as these hormones are typically involved in metabolic processes, and their altered levels signal changes in nutritional or metabolic status of the animal.
• Endometrial gene expressions were examined on Days 7 and 13 after ovulation. Various transcripts, including estrogen and progesterone receptors, fibroblast growth factor, and others associated with embryo development and pregnancy maintenance were inspected.
• Immune cell infiltration in endometrial tissues and protein localisation were studied on Days 7, 10, and 13 post-ovulation. Several proteins, including IGF1 and its receptors and mucin 1 were evaluated.

Key Findings

• The results showed that serum hormone concentrations were not impacted by the reproductive status of the mare.
• Nevertheless, pregnancy downregulated the mRNA levels of estrogen receptor and progesterone receptor, while upregulating the expression of all other investigated genes, implying a significant genetic response to conceiving.
• By contrast, proteins showed variance in expression impacted by both pregnancy and interactions with other variables, such as extraction day and endometrial compartment.
• Moreover, pregnant mares demonstrated a higher lymphocyte count, suggestive of an immune response, which tapered off approaching Day 13.
• Pregnancy’s impact on leucocytes and proteins was more obvious in the superficial compartments of the endometrium.

Conclusion

• The study concludes that equine embryos induce immediate paracrine regulation of critical biological processes. This research adds to the understanding of how early-stage pregnancy modulates maternal physiological systems, orchestrating a supportive environment for embryo development in horses.