title: Aromatase-deficient (ArKO) mice are retrieved from severe hepatic steatosis by peroxisome proliferator administration.
abstract: Tamoxifen is a potent antagonist of estrogen, and hepatic steatosis is a frequent complication in adjuvant tamoxifen for breast cancer. Recently, aromatase-deficient (ArKO, Ar-/-) mice lacking intrinsic estrogen was developed and the molecular mechanism involved in progression of massive hepatic steatosis in estrogen-deficiency was elucidated; impairment in hepatic fatty acid beta-oxidation of peroxisomes, microsomes and mitochondria. This impairment is latent, but is potentially serious, because hepatic energy supply depends greatly on fatty acid beta-oxidation. Therefore in the present study, we tried to conquer impaired hepatic fatty acid beta-oxidation by administrating bezafibrate, a potent peroxisome proliferator, to Ar-/- mice through activating fatty acid beta-oxidation via the peroxisome proliferator activated receptor-alpha mediated signaling pathway. Northern blot analysis of Ar-/- mice liver revealed a significant restoration of mRNA expression of very long fatty acyl-CoA synthetase in peroxisome, peroxisomal fatty acyl-CoA oxidase, and medium-chain acyl-CoA dehydrogenase in mitochondria, essential enzymes in fatty acid beta-oxidation by administration of bezafibrate. Severe hepatic steatosis observed in Ar-/- mice regressed dramatically. Consistent findings were obtained in the in vitro assays of fatty acid beta-oxidation activity. These findings demonstrate that bezafibrate is capable of restoring impaired fatty acid beta-oxidation in vivo via the peroxisome proliferator-activated receptor-alpha mediated signaling pathway and is potent enough to regress severe hepatic steatosis in mice deficient in intrinsic estrogen.
authors.affiliation: Department of Medicine, Kochi Medical School, 783-8505, Nankoku, Japan
authors.forename: Takashi
authors.initials: T
authors.lastname: Yoshikawa
authors.forename: Katsumi
authors.initials: K
authors.lastname: Toda
authors.forename: Yoshihisa
authors.initials: Y
authors.lastname: Nemoto
authors.forename: Masafumi
authors.initials: M
authors.lastname: Ono
authors.forename: Shinji
authors.initials: S
authors.lastname: Iwasaki
authors.forename: Takashi
authors.initials: T
authors.lastname: Maeda
authors.forename: Toshiji
authors.initials: T
authors.lastname: Saibara
authors.forename: Yoshihiro
authors.initials: Y
authors.lastname: Hayashi
authors.forename: Eriko
authors.initials: E
authors.lastname: Miyazaki
authors.forename: Makoto
authors.initials: M
authors.lastname: Hiroi
authors.forename: Hideaki
authors.initials: H
authors.lastname: Enzan
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Shizuta
authors.forename: Saburo
authors.initials: S
authors.lastname: Onishi