title: Novel oxysterols observed in tissues and fluids of AY9944-treated rats: a model for Smith-Lemli-Opitz syndrome.
abstract: Treatment of Sprague-Dawley rats with AY9944, an inhibitor of 3β-hydroxysterol-Δ(7)-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 d(7)-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.
authors.affiliation: Department of Chemistry and Vanderbilt Institute of Chemical Biology, Vanderbilt University, Nashville, TN, USA.
authors.forename: Libin
authors.initials: L
authors.lastname: Xu
authors.forename: Wei
authors.initials: W
authors.lastname: Liu
authors.forename: Lowell G
authors.initials: LG
authors.lastname: Sheflin
authors.forename: Steven J
authors.initials: SJ
authors.lastname: Fliesler
authors.forename: Ned A
authors.initials: NA
authors.lastname: Porter
mesh_terms: D000818:Animals; D000924:Anticholesteremic Agents / Q000494:pharmacology*; D002783:Cholestenones / Q000378:metabolism; D002784:Cholesterol / Q000378:metabolism; D002851:Chromatography, High Pressure Liquid; D003684:Dehydrocholesterols / Q000378:metabolism; D004195:Disease Models, Animal; D006888:Hydroxycholesterols / Q000378:metabolism*; D007653:Ketocholesterols / Q000378:metabolism; D015227:Lipid Peroxidation / Q000187:drug effects; D009682:Magnetic Resonance Spectroscopy; D013058:Mass Spectrometry; D051379:Mice; D051381:Rats; D017207:Rats, Sprague-Dawley; D019082:Smith-Lemli-Opitz Syndrome / Q000188:drug therapy* / Q000378:metabolism / Q000473:pathology; D013056:Spectrophotometry, Ultraviolet; D013261:Sterols / Q000378:metabolism*; D001371:trans-1,4-Bis(2-chlorobenzaminomethyl)cyclohexane Dihydrochloride / Q000494:pharmacology*
chemical_list: D000924:Anticholesteremic Agents; D002783:Cholestenones; D003684:Dehydrocholesterols; D006888:Hydroxycholesterols; D007653:Ketocholesterols; D013261:Sterols; D001371:trans-1,4-Bis(2-chlorobenzaminomethyl)cyclohexane Dihydrochloride; D002784:Cholesterol; C016705:7-dehydrocholesterol; C003001:7-ketocholesterol