Abstract
Given that combined vitamin A (VA) and retinoic acid (RA) supplementation stimulated the intestinal uptake of plasma retinyl esters in neonatal rats, we administrated an RA dose as a pretreatment before VA supplementation to investigate the distinct effect of RA on intestinal VA kinetics. On postnatal days (P) 2 and 3, half of the pups received an oral dose of RA (RA group), while the remaining received canola oil as the control (CN). On P4, after receiving an oral dose of 3H-labeled VA, pups were euthanized at selected times (n = 4–6/treatment/time) and intestine was collected. In both CN and RA groups, intestinal VA mass increased dramatically after VA supplementation; however, RA-pretreated pups had relatively higher VA levels from 10 h and accumulated 30% more VA over the 30-h study. Labeled VA rapidly peaked in the intestine of CN pups and then declined from 13 h, while a continuous increase was observed in the RA group, with a second peak at 10 h and nearly twice the accumulation of 3H-labeled VA compared to CN. Our findings indicate that RA pretreatment may stimulate the influx of supplemental VA into the intestine, and the increased VA accumulation suggests a potential VA storage capacity in neonatal intestine.
Highlights
It is recognized that the first 24 months after birth is a critical period for postnatal development
Female Sprague-Dawley rats were maintained on a Vitamin A (VA) marginal diet during pregnancy and lactation, which effectively restricted the maternal transfer of VA to the newborns; these rat pups may be a good model for infants who are at risk of VA deficiency, such as those in low-income countries
From the VA mass quantification results for the total intestine (Figure 1A,B), we found that VA supplementation increased VA content in the intestine of neonatal rats within the first 4.5 h after dosing, regardless of the pretreatment
Summary
It is recognized that the first 24 months after birth is a critical period for postnatal development. Vitamin A (VA), as an essential micronutrient with a well-established role in a wide range of biological processes, including cell growth, tissue differentiation, and organogenesis in the prenatal period [9,10], as well as the postnatal development of various organs and systems, such as lung, adipose tissue, and neuronal and immune systems, across mammalian species [10,11,12,13]. One of the key roles is in the regulation of immune functions [14], which is of unique importance during the childhood period given the fact that children are highly susceptible to common childhood infections, such as diarrheal, due to their developing and immature immune system, which is distributed across developing organs including the gut, liver, lungs, spleen, and skin
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