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09:01
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Published on: September 15, 2012
Progesterone-Dependent Changes in Platelet Activation Without Morphological Variation in Diestrus Mares.
Katiuska Satué1, Giuseppe Bruschetta2, Esterina Fazio2
1Department of Animal Medicine and Surgery, Faculty of Veterinary Medicine, CEU-Cardenal Herrera University, Tirant lo Blanc, 7, Alfara del Patriarca, 46115 Valencia, Spain.
Veterinary Sciences
|May 26, 2026
Summary
Progesterone influences platelet activation in mares during diestrus, but not platelet morphology or serotonin levels. Mid-diestrus (day 14) is optimal for assessing platelet biomarkers in equine reproductive medicine.
Area of Science:
- Reproductive Endocrinology
- Hematology
- Veterinary Medicine
Background:
- Progesterone (P4) has known vascular and immunomodulatory effects impacting platelet (PLT) activation and serotonin (5-HT) handling.
- The specific role of P4 in modulating equine PLT physiology during diestrus is not well understood.
- Understanding these interactions is crucial for equine reproductive medicine and biomarker development.
Purpose of the Study:
- To investigate the association between circulating P4 levels and changes in PLT aggregation, 5-HT, and PLT morphology during equine diestrus.
- To identify an optimal diestrus sampling day for consistent assessment of PLT-related biomarkers in mares.
Main Methods:
- Blood samples were collected from 20 healthy mares on days 5, 14, and 16 post-ovulation.
- Progesterone (P4) and serotonin (5-HT) concentrations were measured using radioimmunoassay and enzyme immunoassay, respectively.
- Platelet indices and aggregation were analyzed using an ADVIA 2120i hematology analyzer.
Main Results:
- Circulating P4 concentrations were significantly higher on days 14 and 16 compared to day 5.
- Platelet aggregates (AGREG) were significantly higher on day 14 versus day 5.
- Circulating 5-HT and all measured PLT morphological indices remained unchanged throughout diestrus; PLT aggregation positively correlated with P4.
Conclusions:
- During equine diestrus, PLT activation, but not PLT morphology or circulating 5-HT, varies with P4 levels.
- Mid-diestrus (day 14) presents consistent physiological conditions and is suitable for assessing PLT activation biomarkers.
- This study provides a framework for standardizing sampling protocols for PLT-derived products in equine reproductive medicine.
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