Maternal LDHB Safeguards Redox Balance and Developmental Competence During Preimplantation Embryo Cleavage

Area of Science:

• Reproductive Biology
• Developmental Biology
• Metabolic Regulation

Background:

• Embryonic metabolic regulation differs from somatic cells.
• Early mammalian embryos rely on maternal nutrients for energy.
• Lactate is a key substrate in embryonic energy metabolism.

Purpose of the Study:

• To investigate the role of maternal Lactate dehydrogenase B (LDHB) in early mammalian embryogenesis.
• To understand the impact of LDHB inhibition on embryonic development and metabolic state.
• To explore rescue mechanisms for developmental defects caused by LDHB inhibition.

Main Methods:

• Transient inhibition of maternally supplied Lactate dehydrogenase B (LDHB) in early embryos.
• Assessment of developmental progression, ATP levels, mitochondrial function, and NAD+/NADH ratio.
• Evaluation of aspartate supplementation and malate-aspartate shuttle (MAS) activity for rescue.

Main Results:

• LDHB inhibition caused developmental arrest at the 4- to 8-cell stage.
• Inhibited embryos showed reduced ATP, impaired mitochondrial activity, and a lower NAD+/NADH ratio.
• Aspartate supplementation rescued development and restored NAD+/NADH balance via the MAS.

Conclusions:

• Maternal LDHB is vital for maintaining redox homeostasis during the 4- to 8-cell transition.
• Malate-aspartate shuttle activity is crucial for redox restoration during rescue.
• Metabolic flexibility, redox homeostasis, and developmental competence are interconnected in early mammalian development.