Utilization of carbon from dietary polyunsaturates for brain cholesterol synthesis during early postnatal development in the rat: a 13c nmr study

Authors

  • Sergei S. Likhodii PhD,

    Corresponding author
    1. S.S.L is on leave from the Institute of Chemical Physics, Russian Academy of Sciences, Moscow, Russia.
    2. the Department of Nutritional Sciences, Faculty of Medicine, University of Toronto, Toronto, Canada.
    • Department of Nutritional Sciences, University of Toronto, Toronto, Canada M5S 1A8
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  • Stephen C. Cunnane

    1. the Department of Nutritional Sciences, Faculty of Medicine, University of Toronto, Toronto, Canada.
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Abstract

Incorporation of 13C from a dietary precursor into cholesterol was studied in neonatal rats. Rats were given uniformly 13C-enriched polyunsaturated fatty acids intragastrically and total lipid extracts of liver and brain were analyzed by 13C-NMR 1,4, 8, and 15 days later. 13C-enrichment was detected in brain but not in liver cholesterol. Maximal 13C-labeling was observed 4 days after injection of the label. Spectra revealed that 70% of newly incorporated 13C had 13C as an adjacent neighbor, the other 30% had 12C as the neighbor. Double quantum NMR revealed the arrangement in the cholesterol skeleton of the 13C-13C pairs transferred from precursors to cholesterol. Desmosterol, an intermediate of cholesterol synthesis, was identified in the spectra of brain lipids. Comparison of 13C-13C unit arrangements in both cholesterol and desmosterol allowed carbons 26 and 27 of desmosterol to be unambiguously assigned.

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