Immunolocalization of Leptin and its Receptor (ObR-b) in Equine Placenta at Term and Plasma Level Measurement in the Late Gestation.
Authors: Pazinato Fernanda Maria, Curcio Bruna da Rosa, Varela Junior Antonio Sergio, Corcini Carine Dahl, Wendt Camila Gervini, Moreira Fabiana, Schmit Rubia Alves, Nogueira Carlos Eduardo Wayne
Journal: Journal of equine veterinary science
Summary
# Editorial Summary Leptin, a hormone critical to metabolic regulation and reproductive function, has been detected in equine placentae, yet its precise anatomical distribution and functional role during pregnancy remain poorly characterised. Researchers immunolocalised leptin and its functional receptor (ObR-b) in placental tissue from eight pregnant Criollo mares, whilst simultaneously measuring plasma leptin concentrations during the final three months of gestation, at parturition, and 24 hours post-foaling via radioimmunoassay. Leptin and ObR-b were identified in the cytoplasm of pseudostratified epithelial cells within areolar regions and microcotyledon epithelia, with receptor expression also present on the apical cell surface; plasma leptin remained stable from month eight through ten of gestation before declining modestly in the 24 hours following birth (P = 0.07). The co-localisation of leptin and its receptor in these functionally important placental compartments indicates the hormone operates through both endocrine pathways (systemic effects) and local autocrine/paracrine mechanisms (direct tissue regulation), suggesting leptin plays a substantive role in placental physiology beyond simple metabolic signalling. This characterisation may inform future investigations into placental insufficiency, in utero growth restriction, and metabolic complications in late-gestation mares, potentially offering novel biomarkers for monitoring fetal and maternal wellbeing during high-risk pregnancies.
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Practical Takeaways
- •Leptin plays a regulatory role in equine placental function during late gestation; monitoring leptin-related pathways may help assess placental health in late-pregnant mares
- •Understanding leptin's presence and distribution in equine placenta provides foundational knowledge for investigating placental insufficiency or metabolic complications in late gestation
- •Stable plasma leptin through late gestation suggests this hormone is not a primary driver of periparturient metabolic changes in mares, unlike in some other species
Key Findings
- •Leptin and its receptor (ObR-b) were immunolocalized in the cytoplasm of pseudostratified epithelial cells in equine placental areolar regions and microcotyledon epithelium at term
- •Leptin receptor was specifically allocated to the apical surface of placental cells
- •Plasma leptin concentrations remained stable from the 8th to 10th month of gestation with discrete decrease 24 hours post-parturition (P = 0.07)
- •Findings support endocrine and autocrine/paracrine actions of leptin within the equine placenta