Placental adaptation to maternal environment in domestic animals.

Overview

• This research article reviews how the placenta in domestic animals adapts to different maternal environmental conditions.
• It highlights the ways placental changes influence fetal development and long-term health, emphasizing species-specific differences and potential applications for monitoring and intervention.

Developmental Origins of Health and Disease (DOHaD) Framework

• DOHaD suggests that environmental factors during critical developmental periods affect lifelong health and disease risk.
• Traditionally, fetal organs are viewed as the main programming targets, but this article stresses the pivotal role of the placenta as a mediator.
• The placenta senses and responds to maternal environmental inputs, shaping the fetal environment through key functions like nutrient transfer, hormone signaling, and immune system regulation.

Placental Plasticity and Mechanisms of Adaptation

• Placental plasticity refers to the placenta’s ability to alter its morphology and function in response to maternal environment changes.
• Key adaptive mechanisms include:
• Changes in tissue structure and topology to optimize nutrient and oxygen exchange.
• Vascular development and blood flow adjustments to improve placental perfusion.
• Modification of nutrient transporter density and localization to regulate fetal nutrient supply.
• Adjustments in mitochondrial metabolism influencing energy production within placental cells.
• Modulation of inflammatory states and endocrine outputs affecting fetal development signals.
• These adaptations help ensure short-term fetal survival but can also alter developmental programming with lasting effects, especially if prenatal and postnatal environments differ significantly.

Species-Specific Placental Adaptation in Domestic Animals

• Ruminants (e.g., cattle, sheep):
• Have cotyledonary placentas composed of multiple placentomes.
• Adaptations under maternal undernutrition include altering placentome type and increasing blood vessel growth to maintain nutrient supply.
• Heat stress induces placental remodeling linked to changes in inflammation, oxygen management, and gene regulation (epigenomic and transcriptomic level), affecting neonatal outcomes.
• Horses:
• Possess diffuse microcotyledonary placentas where fetal growth relates to allantochorion size and microcotyledon density.
• Placental vascular structure and gene expression are influenced by maternal factors such as uterine capacity, age, parity, and metabolic status.
• These placental changes impact postnatal growth and metabolic health in foals.
• Pigs:
• Have diffuse folded placentas and are litter-bearing, which introduces competition among fetuses.
• Intrauterine crowding and maternal heat stress lead to structural changes in placental folds and efficiency-related changes in nutrient transporter expression.
• These adaptations affect nutrient transport and metabolic gene networks, contributing to variability in fetal development within litters.

Epigenetics and Molecular “Memory” of Placental Adaptation

• The placenta retains epigenetic marks—chemical modifications influencing gene expression—that record environmental exposures during pregnancy.
• This molecular “memory” can have lasting effects on offspring health and development.
• The article highlights the importance of studying these epigenetic changes to better understand how in utero environments impact placental and fetal outcomes.

Future Directions and Practical Applications

• There is a need for in vivo biomarkers that accurately reflect placental function and fetal environment adaptations during pregnancy.
• Promising candidates include circulating placental extracellular vesicles and microRNAs detectable in maternal blood.
• Combining these biomarkers with detailed placental phenotyping could improve risk assessment in pregnancy.
• Such advances would enable targeted interventions in veterinary medicine and animal production settings to enhance offspring health and productivity.