Chronic vitamin A status and age affect the activity of liver lecithin: Retinol acyltransferase (LRAT)

Y. Yamamoto, H. D. Dawson, D. Weinstock, T. Shimada, A. Catharine Ross

Research output: Contribution to journalArticle

Abstract

Newly absorbed vitamin A (VA) is stored in the liver as esterified retinol. LRAT, a microsomal enzyme, is implicated in this process. We have shown previously that liver LRAT activity is regulated by VA status and exogenous retinoids. However, the effect of long-term VA status (chronic VA-marginal, control, or VA-supplemented diets), or of age, on liver LRAT activity is unknown. In this study, rats were fed diets (VA-marginal, control, or VA-supplemented) until they were 2, 8-10 or 18-20 mo old (9 diet-age groups, n=6 rats/group). Liver tissue was fixed for light and electron microscopy and LRAT activity was measured in liver homogenates using 3H-retinol bound to cellular retinol-binding protein, CRBP, as substrate. By 2-way ANOVA, VA status significantly affected liver LRAT activity (P<0.0001), but age did not. However, the interaction between VA status and age was highly significant (P<0.0001). For all ages, LRAT activity was low (averaging 20.2% of control, P<0.05) in VA-marginal rats and elevated (139.3% of control, P<0.05) in VA-supplemented rats. With increasing age, liver LRAT activity declined in VA-marginal rats, while it increased slightly but significantly in VA-supplemented rats. Liver LRAT activity was positively correlated with total plasma VA. Hepatic morphology changed with age and VA status. We conclude that within a range of chronic VA status that excludes VA deficiency and toxicity, there is significant regulation of liver LRAT activity which is correlated with plasma total retinol concentration.

Original languageEnglish (US)
JournalFASEB Journal
Volume11
Issue number3
StatePublished - Dec 1 1997

All Science Journal Classification (ASJC) codes

  • Biotechnology
  • Biochemistry
  • Molecular Biology
  • Genetics

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