Ketoconazole normalized hepatic levels of intermediates in bile acid biosynthesis in Cyp27-/- mice

Abstract

Background: Mice with disrupted C'rT'27A1 gene showed elevated hepatic concentrations of cholestanol, bile alcohols, and intermediates in classic bile acid biosynthetic pathway. However, these levels were lower than those found m patients with cerebrotendinous xanthomatosis (CTX) and the mice did not show CTX symptoms. Since markedly up-regulated hepatic Cyp3A activity in Cyp27-/mice was unlike CTX, we tried to inhibit Cyp3A activity of Cyp27-/mice by ketocotuzole. Methods: The ketoconazole, 125 mg/Kg (n = 4) or placebo (n = 4) was administered lot 8 days by nasogasmc garage to each Cyp27-/mouse. Hepatic sterol concentrations and enzyme acmaUes were measmvd by high-resolution GC-SIM. Results: Sigrnficantly elevated hepatic concentrations of cholestanoI (2-fold), 7c~&ydmxycholesterol (24-fold), 5[3<holestane-3r 12u-trio1 (51-tbld), and bile alcohols (more than 12-fold) were obsereed in Cyp27-A mice compared with Cyp27 + / + mice. After ketoconazole treatment, tfm devated stemls were reduced to the levels in Cyp27 + / + mice. No 27hydroxycholestero| was detected in Cyp27-/mice livers, but 27-bydroxycholesterol was produced in Cy1~27-/m~ce after ketoconazole treatment Chnlesterol and 24S-hydroxycholesterol concentrations in Cyp27/mice hver were not significantly different flom those in C y p 2 7 + / + mice, and ketoconazole treatment did not change these levels. Hepatic microsomal activities of tIMG-CoA reductase, Cyp7A1, and Cyp3A ,*ere markedly upregulated in Cyp27-A rmce (1 l 6~, and 5-told, respectlvdy) wbile these enzyme activities were inhibited to the levels of C y p 2 7 + / + mice aiier ketoconazole treatment Hepatic mitochondrial cholesterol 27&ydroxylase activity was not detected in Cy'p27-/mice, but was cibserved in CEp27-/mice after kdoconazole treatment Conclusions: Ketoconazole inhibited microsomal HMG-CoA reductase, Cyp7Al, and Cyp3A activities and induced mitochondna127-hydrnxTlase activity in Cyp27-A mice, such that hepatic levels of intermediates in bile acid biosynthesis were normalized. The results suggest that 27-hydroxy/atiou of cholesterol was catalyzed not only by Cyp27A1 but also another mltochondrial enzyme(s) induced by ketoconazole