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J Nutr. 2015 Mar;145(3):403-10. doi: 10.3945/jn.114.204065. Epub 2014 Dec 24.

Vitamin A kinetics in neonatal rats vs. adult rats: comparisons from model-based compartmental analysis.

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Department of Nutritional Sciences, and.
Department of Nutritional Sciences, and The Huck Institutes for the Life Sciences, The Pennsylvania State University, University Park, PA


A critical role for vitamin A (VA) in development is well established, but still relatively little is known about whole-body VA metabolism in early postnatal life. Recently, methods of mathematical modeling have begun to shed light on retinol kinetics in the postnatal growth period and on the effect of retinoid supplementation on retinol kinetics. Comparison of kinetic parameters from tracer studies in neonatal rats with those previously determined in models of VA metabolism in the adult suggests both similarities and differences in the relative transfer rates of plasma retinol to extrahepatic tissues, resulting in similarities and differences in kinetic parameters and inferences about physiologic processes. Similarities between neonatal and adult models include the capacity for efficient digestion and absorption of VA; characteristics of a high-response system; extensive retinol recycling among liver, plasma, and extrahepatic tissues; and comparable VA disposal rates. Differences between neonatal and adult models include that, in neonates, retinol turnover is faster and retinol recycling is much more extensive; there is a greater role for extrahepatic tissues in the uptake of chylomicron VA; and the intestine plays an important role in chylomicron VA uptake, especially in neonatal rats treated with a supplement containing VA. In summary, retinol kinetic modeling in the neonatal rat has provided a first view of whole-body VA metabolism in this age group and suggests that VA kinetics in neonatal rats differs in many ways from that in adults, perhaps reflecting an adaption to the lower VA concentration found in neonates compared with adults.


chylomicron vitamin A uptake; extrahepatic vitamin A metabolism; mathematical modeling; neonate; retinol kinetics; vitamin A supplementation

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