Vitamin A combined with retinoic acid increases retinol uptake and lung retinyl ester formation in a synergistic manner in neonatal rats

A. Catharine Ross, Namasivayam Ambalavanan, Reza Zolfaghari, Nan Qian Li

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Vitamin A (VA) is stored in tissues predominantly as retinyl esters (REs), which provide substrate for the production of bioactive retinoids. Retinoic acid (RA), a principal metabolite, has been shown to induce postnatal lung development. To better understand lung RE storage, we compared VA (given as retinyl palmitate), RA, and a nutrient-metabolite combination, VARA, given orally on postnatal days 5-7, for their ability to increase lung RE in neonatal rats. VARA increased lung RE significantly [∼14, 2.4, 2.1, and <1 nmol/g for VARA, VA, RA, and control (C), respectively; P < 0.001]; the increase by VARA was more than additive compared with the effects of VA and RA alone. Lung histology and morphometry were unchanged. In a 6 h metabolic study, providing [3H]retinol with VARA, compared with VA or C, increased the uptake of newly absorbed 3H by 3-fold, indicating that VARA stimulated the uptake of [3H]retinol and its retention as [3H]RE in neonatal lungs. After cessation of VARA, lung RE remained increased for 9 d afterward, through the period of alveolar development. In conclusion, VARA, a 10:1 nutrient-metabolite combination, increased lung RE significantly compared with VA alone and could be a promising therapeutic option for enhancing the delivery of VA to the lungs.

Original languageEnglish (US)
Pages (from-to)1844-1851
Number of pages8
JournalJournal of Lipid Research
Issue number8
StatePublished - Aug 18 2006


All Science Journal Classification (ASJC) codes

  • Biochemistry
  • Endocrinology
  • Cell Biology

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