Expression of Oxytocin/Neurophysin I and Oxytocinase in the Equine Conceptus from Day 8 to Day 21 Post-Ovulation.
Authors: Diel de Amorim Mariana, Klein Claudia, Foster Robert, Dong Lynn, Lopez-Rodriguez Maria Fernanda, Card Claire
Journal: Animals : an open access journal from MDPI
Summary
# Editorial Summary Oxytocin and its metabolising enzyme oxytocinase (LNPEP) have established roles in maternal pregnancy recognition and uterine contractions, yet their expression patterns in the developing equine conceptus remain poorly characterised. Diel de Amorim and colleagues used quantitative gene expression analysis across days 8–21 post-ovulation, complemented by immunohistochemistry, western blotting and mass spectrometry on days 15–18 conceptuses, to map the temporal and spatial distribution of oxytocin/neurophysin I and LNPEP. Oxytocinase protein increased significantly by day 15 and localised to the trophectoderm and endoderm, whilst oxytocin gene expression peaked at day 21 but no corresponding protein was detected; notably, oxytocinase expression correlated strongly with prostaglandin synthase and receptor genes between days 12–15, suggesting a coordinated regulatory pathway. These findings propose that embryonic oxytocinase may regulate local oxytocin availability to modulate prostaglandin signalling during the critical window of conceptus fixation, potentially protecting the developing pregnancy from premature uterine contractions. For practitioners involved in early pregnancy management and those investigating pregnancy loss or fixation failure, this work underscores the importance of the embryo's own biochemical defences and warrants further investigation into how systemic or local factors affecting oxytocinase activity might influence pregnancy establishment.
Read the full abstract on PubMed
Practical Takeaways
- •Understanding embryonic oxytocinase expression may inform management of early equine pregnancy, particularly during the critical period of conceptus fixation around days 12-16
- •The metabolic regulation of oxytocin by LNPEP during early pregnancy could have implications for conception rates and pregnancy loss prevention in mares
- •Further research is needed to translate these molecular findings into practical reproductive management strategies for equine practitioners
Key Findings
- •LNPEP (oxytocinase) expression increased significantly at day 15 post-ovulation compared to day 10 in equine conceptuses
- •LNPEP protein was localized to the trophectoderm and endoderm, confirmed by LC-MS/MS analysis
- •OXT gene expression peaked at day 21 with lowest levels on days 12-14, though oxytocin protein was not detected
- •LNPEP correlated with prostaglandin-related genes (PTGFR, PTGES) suggesting a role in regulating oxytocin availability during conceptus fixation