title: High doses of simvastatin, pravastatin, and cholesterol reduce brain cholesterol synthesis in guinea pigs.
abstract: Recent epidemiological studies suggest that inhibitors of 3-hydroxy-3-methyl-glutaryl CoA reductase, so-called statins, are effective in lowering the prevalence of Alzheimer's disease. Whether the effect of statins is due to a local inhibition of cholesterol synthesis in the brain or whether it is mediated by the reduced levels of cholesterol in the circulation is not known. In the present work, we tested the possibility that high doses of lipophilic and hydrophilic statins, simvastatin and pravastatin, respectively, or a diet high in cholesterol could affect cholesterol homeostasis in the brain of guinea pigs. The total brain cholesterol levels were not affected by high-dose simvastatin or pravastatin treatment. Significantly lower levels of the cholesterol precursor lathosterol and its ratio to cholesterol were found in the brains of simvastatin and pravastatin-treated animals. 24S-Hydroxycholesterol, the transportable form of cholesterol across the blood-brain barrier, was significantly lower in the brain of pravastatin-treated animals. Excessive cholesterol feeding resulted in higher serum cholesterol levels but did not affect total brain cholesterol level. However, de novo cholesterol synthesis in the brain seemed to be down-regulated, as indicated by lower absolute levels and cholesterol-related ratios of lathosterol compared with controls. The passage of deuterium-labeled cholesterol across the blood-brain barrier in one animal was found to be approximately 1%. Our results suggest that brain cholesterol synthesis in guinea pigs can be slightly, but significantly, influenced by high doses of lipophilic and hydrophilic statins as well as by high dietary cholesterol intake, while total brain cholesterol content and thus, cholesterol homeostasis is maintained.
authors.affiliation: Department of Clinical Pharmacology, University of Bonn, Sigmund-Freud-Str. 25, 53105 Bonn, Germany. d.luetjohann@uni-bonn.de
authors.forename: Dieter
authors.initials: D
authors.lastname: Lütjohann
authors.forename: Mark
authors.initials: M
authors.lastname: Stroick
authors.forename: Thomas
authors.initials: T
authors.lastname: Bertsch
authors.forename: Sandra
authors.initials: S
authors.lastname: Kühl
authors.forename: Bernhard
authors.initials: B
authors.lastname: Lindenthal
authors.forename: Karin
authors.initials: K
authors.lastname: Thelen
authors.forename: Ulla
authors.initials: U
authors.lastname: Andersson
authors.forename: Ingemar
authors.initials: I
authors.lastname: Björkhem
authors.forename: Klaus von
authors.initials: Kv
authors.lastname: Bergmann Kv
authors.forename: Klaus
authors.initials: K
authors.lastname: Fassbender
mesh_terms: D000818:Animals; D001921:Brain / Q000187:drug effects* / Q000378:metabolism; D002460:Cell Line; D002784:Cholesterol / Q000008:administration & dosage / Q000096:biosynthesis* / Q000097:blood / Q000494:pharmacology*; D000072556:Cholesterol 24-Hydroxylase; D006168:Guinea Pigs; D006801:Humans; D006888:Hydroxycholesterols / Q000378:metabolism; D008297:Male; D017035:Pravastatin / Q000008:administration & dosage* / Q000494:pharmacology*; D019821:Simvastatin / Q000008:administration & dosage* / Q000494:pharmacology*; D013250:Steroid Hydroxylases / Q000235:genetics / Q000378:metabolism; D013261:Sterols / Q000097:blood / Q000378:metabolism; D014162:Transfection
chemical_list: D006888:Hydroxycholesterols; D013261:Sterols; C044563:24-hydroxycholesterol; D002784:Cholesterol; D019821:Simvastatin; D013250:Steroid Hydroxylases; D000072556:Cholesterol 24-Hydroxylase; D017035:Pravastatin