Choline Kinetics in Neonatal Liver, Brain and Lung-Lessons from a Rodent Model for Neonatal Care

Area of Science:

• Biochemistry
• Nutritional Science
• Developmental Biology

Background:

• Choline is crucial for fetal and preterm infant development, essential for phosphatidylcholine (PC) synthesis and one-carbon metabolism.
• Choline metabolism in vital organs during rapid neonatal growth remains poorly understood.
• Understanding choline's role is critical for determining optimal nutritional requirements in vulnerable populations.

Purpose of the Study:

• To investigate the kinetics of exogenous D9-choline and its metabolites in neonatal rat organs.
• To elucidate the pathways of choline utilization, including PC synthesis and betaine formation.
• To determine organ-specific uptake and distribution of choline metabolites.

Main Methods:

• Intraperitoneal injection of D9-choline chloride (50 mg/kg) into 14-day-old rats.
• Sacrifice of animals at 1.5, 6, and 24 hours post-injection.
• Analysis of D9-choline metabolites in liver, plasma, brain, and lung tissue using tandem mass spectrometry.

Main Results:

• D9-PC and D9-betaine were significant metabolites within 1.5 hours in all analyzed organs.
• D9-PC peaked early in all organs but showed distinct kinetics: decreasing in liver/lung, but increasing in brain/lung from 6-24h.
• The liver appears to supply PC to the brain and lung via plasma, with subsequent organ-specific acyl remodeling, while betaine rapidly enters the one-carbon pool.

Conclusions:

• Exogenous choline is rapidly converted to PC in neonatal rat organs, with the liver acting as a key supplier to the brain and lung.
• Organotypic acyl remodeling of PC occurs after uptake, indicating complex metabolic handling.
• A significant portion of choline is converted to betaine, impacting one-carbon metabolism and choline requirement calculations.