Journal of Lipid Research
Volume 52, Issue 10, October 2011, Pages 1810-1820
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Research Articles
Novel oxysterols observed in tissues and fluids of AY9944-treated rats: a model for Smith-Lemli-Opitz syndrome

https://doi.org/10.1194/jlr.M018366Get rights and content
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Treatment of Sprague-Dawley rats with AY9944, an inhibitor of 3β-hydroxysterol-Δ7-reductase (Dhcr7), leads to elevated levels of 7-dehydrocholesterol (7-DHC) and reduced levels of cholesterol in all biological tissues, mimicking the key biochemical hallmark of Smith-Lemli-Opitz syndrome (SLOS). Fourteen 7-DHC-derived oxysterols previously have been identified as products of free radical oxidation in vitro; one of these oxysterols, 3β,5α-dihydroxycholest-7-en-6-one (DHCEO), was recently identified in Dhcr7-deficient cells and in brain tissues of Dhcr7-null mouse. We report here the isolation and characterization of three novel 7-DHC-derived oxysterols (4α- and 4β-hydroxy-7-DHC and 24-hydroxy-7-DHC) in addition to DHCEO and 7-ketocholesterol (7-kChol) from the brain tissues of AY9944-treated rats. The identities of these five oxysterols were elucidated by HPLC-ultraviolet (UV), HPLC-MS, and 1D- and 2D-NMR. Quantification of 4α- and 4β-hydroxy-7-DHC, DHCEO, and 7-kChol in rat brain, liver, and serum were carried out by HPLC-MS using d7-DHCEO as an internal standard. With the exception of 7-kChol, these oxysterols were present only in tissues of AY9944-treated, but not control rats, and 7-kChol levels were markedly (>10-fold) higher in treated versus control rats. These findings are discussed in the context of the potential involvement of 7-DHC-derived oxysterols in the pathogenesis of SLOS.—.

cholesterol
cholesterol/biosynthesis
lipids/peroxidation
7-dehydrocholesterol

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This work was supported by United States Public Health Service (National Institutes of Health) Grants ES-013125 (N.A.P.), HD-064727 (N.A.P.), and EY-007361 (S.J.F.), National Science Foundation Grants CHE 0717067 (N.A.P.), and by an unrestricted grant from Research to Prevent Blindness (S.J.F.). Its contents are solely the responsibility of the authors and do not necessarily represent the official views of the National Institutes of Health.

    Abbreviations:

    APCI

    atmospheric pressure chemical ionization

    Chol

    cholesterol

    COSY

    correlation spectroscopy

    CYP46A1

    cytochrome P450 46A1 (cholesterol 24-hydroxylase)

    1D

    one dimensional

    7-DHC

    7-dehydrocholesterol

    DHCEO

    3β,5α-dihydroxycholest-7-en-6-one

    Dhcr7 or DHCR7

    3β-hydroxysterol-Δ7-reductase

    EnP(5,8)

    5α,8α-epidioxy-cholest-6-en-3β-ol

    HMBC

    heteronuclear multiple bond correlation

    HSQC

    heteronuclear single quantum correlation

    7-kChol

    7-ketocholesterol

    NOESY

    nuclear Overhauser effect spectroscopy

    NP

    normal-phase

    RP

    reverse-phase

    SLOS

    Smith-Lemli-Opitz syndrome

    SRM

    selective reaction monitoring

    UV

    ultraviolet

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