title: Ovariectomy stimulates hepatic fat and cholesterol accumulation in high-fat diet-fed rats.
abstract: This study was designed to determine how estrogens withdrawal during a high-fat (HF) diet regimen affects liver triacylglycerol (TAG) and cholesterol accumulation. Female Sprague-Dawley rats were submitted to a HF (42% energy as fat) or a standard (SD) diet for 6 weeks before being either ovariectomized (Ovx) or sham operated (Sham). Thereafter, Ovx and Sham rats were kept on the same diet for another 6 weeks leading to euthanasia. Liver TAG content was increased (p<0.01) in Ovx rats but not by the HF diet alone. However, the combination of HF diet and Ovx resulted in a greater liver TAG accumulation (p<0.06) than that observed in Ovx-SD/SD. Measurement of molecular markers of liver lipid metabolism revealed an increase in transcripts of markers of lipid oxidation (CPT-1 and PGC1; p<0.05) in rats fed the HF diet. This increase was, however, substantially less if HF fed rats were Ovx. Liver total cholesterol levels were increased (p<0.01) only in the Ovx-HF/HF rats while plasma cholesterol levels were increased in Ovx-SD/SD and in SHAM-HF/HF and Ovx-HF/HF rats. Transcripts of molecular markers of cholesterol metabolism suggest that biliary acids synthesis (CYP7a-1) was reduced in Ovx-SD/SD and Sham-HF/HF rats and even more so in Ovx-HF/HF rats. It is concluded that the effects of a HF diet on liver TAG accumulation are especially observed in Ovx rats possibly through a reduction in hepatic lipid oxidation. The combination of Ovx and HF diet also acts synergistically to favor liver cholesterol accumulation.
authors.affiliation: Department of Kinesiology, Université de Montréal, Montréal, Québec, Canada.
authors.forename: E T
authors.initials: ET
authors.lastname: Ngo Sock
authors.forename: I
authors.initials: I
authors.lastname: Côté
authors.forename: J S
authors.initials: JS
authors.lastname: Mentor
authors.forename: D
authors.initials: D
authors.lastname: Prud'homme
authors.forename: R
authors.initials: R
authors.lastname: Bergeron
authors.forename: J-M
authors.initials: JM
authors.lastname: Lavoie
mesh_terms: D000818:Animals; D002784:Cholesterol / Q000378:metabolism*; D002790:Cholesterol 7-alpha-Hydroxylase / Q000378:metabolism; D004041:Dietary Fats / Q000009:adverse effects / Q000493:pharmacokinetics*; D005260:Female; D050356:Lipid Metabolism; D008099:Liver / Q000378:metabolism* / Q000473:pathology; D010052:Ovariectomy; D051381:Rats; D017207:Rats, Sprague-Dawley; D014280:Triglycerides / Q000378:metabolism*
chemical_list: D004041:Dietary Fats; D014280:Triglycerides; D002784:Cholesterol; C532838:CYP7A1 protein, rat; D002790:Cholesterol 7-alpha-Hydroxylase