Adaptive Response of Estrogen-Iron Axis in Pregnant Purebred Spanish Mares of Different Age.
Authors: Satué Katiuska, Fazio Esterina, La Fauci Deborah, Bruschetta Giuseppe, Medica Pietro
Journal: Journal of equine veterinary science
Summary
# Editorial Summary As mares age, their ability to regulate iron availability during pregnancy becomes progressively compromised, despite elevated oestrogen concentrations that would normally facilitate iron mobilisation in younger animals. Researchers examined serum iron, ferritin, hepcidin, oestrone and oestradiol-17β in 40 Spanish Purebred mares across four age groups (4–6, 7–9, 10–12, and >12 years), revealing a marked reversal of the "oestrogen-iron axis" with advancing age. Younger mares (4–9 years) demonstrated significantly higher serum iron and ferritin concentrations alongside lower hepcidin levels, with strong negative correlations between iron stores and hepcidin (r = −0.81), suggesting efficient hormonal suppression of hepcidin and consequent iron mobilisation for erythropoietic expansion and placental development. By contrast, mares aged >12 years showed elevated hepcidin and reduced oestrone despite higher oestradiol-17β concentrations, indicating a loss of this compensatory mechanism and less efficient iron metabolism. For practitioners managing pregnant mares—particularly older breeding animals—these findings underscore the importance of proactive iron status monitoring and supplementation strategies, as the physiological adaptations that younger mares employ naturally become unreliable with age, potentially affecting both maternal and fetal welfare.
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Practical Takeaways
- •Older broodmares (>12 years) may have compromised iron mobilization during pregnancy due to altered estrogen-hepcidin regulation; monitoring iron status and considering supplementation may be warranted in geriatric pregnant mares
- •Younger mares (4-9 years) demonstrate more efficient physiological adaptation to iron demands of pregnancy through better estrogen-mediated hepcidin suppression, suggesting age should factor into breeding program decisions
- •Routine serum iron, ferritin, and hepcidin assessment could help identify pregnant mares at risk of iron-related complications, particularly those >12 years of age
Key Findings
- •Serum iron and ferritin concentrations were significantly higher in younger mares (4-9 years) compared to older mares (10+ years), with P < 0.01
- •Hepcidin concentrations increased and estrone decreased in mares >12 years compared to younger age groups (P < 0.01)
- •Iron and ferritin showed strong negative correlation with hepcidin (r = -0.81 and r = -0.67 respectively), while estradiol-17β showed positive correlation with hepcidin (r = 0.78)
- •An 'estrogen-iron axis' appears efficient in young pregnant mares but becomes reversed and less efficient in older mares, suggesting age-related decline in iron metabolism during pregnancy