Compartment-specific placental adaptation following feed restriction and refeeding in rabbits: implications for fetal...

Placental development is highly sensitive to maternal nutrition and influences fetal growth and reproductive success. Moderate maternal feed restriction (FR) during gestation can reduce feeding costs on farms, but its impact on the placenta and productive performance in females and offspring remains unclear. This study characterised compartment-specific placental adaptations and their productive consequences in multiparous rabbit does subjected to a 40% nutritional restriction during the first two-thirds of gestation (Day 0 to 21), followed by ad libitum refeeding. On day 28 of gestation, seven days after refeeding began, placental morphometry, histology, efficiency, and gene expression was characterized alongside fetal growth and viability. Maternal body weight and feed intake during gestation, fertility, prolificacy, and postnatal outcomes during lactation were also assessed. Placental efficiency was reduced (P < 0.05), and was accompanied by proportional decreases in fetal head and body weight (P < 0.05), consistent with a generalized restriction of fetal growth. The labyrinth exhibited hemorrhage and fibrosis with subsequent reduced cellularity. Furthermore, the main glucose transporter (SLC2A1) was donwregulated in both placental compartments, whereas genes related to anaerobic glycolysis (LDHA, GAPDH), NO-related signalling (eNOS), and fetal growth regulation (IGF2R) were upregulated in the fetal placenta compartment of FR does (P < 0.05). VEGF expression and localization were not affected by the restriction-refeeding protocol. Late-gestation refeeding restored maternal body weight, and did not compromise fertility or offspring survival, althought lower stillbirths in FR does were found (P < 0.05). Overall, the restriction-refeeding regime induces compartment-specific placental adaptations associated with reduced placental efficiency and fetal growth, while fetal survival and postnatal viability areunaffected. These findings highlight placental plasticity in response to maternal nutrition and support the rabbit as a valuable model for placental adaptation to maternal undernutrition.