title: Effects of estrogen on atherosclerosis formation and serum nitrite/nitrate concentrations in cholesterol-fed ovariectomized rabbits.
abstract: This study was to examine the effects of estrogen replacement on atherosclerosis formation in ovariectomized cholesterol-fed rabbits. We also examined serum levels of nitrite/nitrate, stable metabolites of nitric oxide, to investigate the involvement of nitric oxide. Female New Zealand White rabbits were ovariectomized and divided into 3 groups; 1) fed a normal diet (ND group, n=5), 2) fed a 1% cholesterol diet (CD group, n=6), or 3) fed a 1% cholesterol diet and received estrogen replacement (CD+E group, n=7). After 3 months, the rabbits were sacrificed to examine atherosclerosis formation. Atherosclerosis was not observed in ND. The oil red 0 positive area in the aorta was significantly greater in CD than in CD+E (CD, 17.3+/-2.2; CD+E, 9.3+/-0.8%, p<0.05). Stenosis of the coronary artery was also significantly greater in CD than in CD+E (CD, 30.6+/-9.7; CD+E, 6.7+/-2.9%, p <0.05). There was no significant difference in serum lipids between CD and CD+E. Serum nitrite/nitrate levels were significantly lower in CD than in ND (ND, 37.6+/-3.6; CD, 25.3+/-3.1 microM, p<0.05). There was a non-significant trend towards higher nitrite/nitrate levels after estrogen replacement (CD+E, 34.4+/-3.8 microM, p=0.08 vs. CD). These results suggest that direct actions on vascular wall including nitric oxide production contribute to the anti-atherogenic effects of estrogen.
authors.affiliation: Department of Geriatrics, Faculty of Medicine, University of Tokyo, Japan.
authors.forename: M
authors.initials: M
authors.lastname: Akishita
authors.forename: K
authors.initials: K
authors.lastname: Kozaki
authors.forename: T
authors.initials: T
authors.lastname: Saito
authors.forename: M
authors.initials: M
authors.lastname: Eto
authors.forename: M
authors.initials: M
authors.lastname: Ishikawa
authors.forename: H
authors.initials: H
authors.lastname: Miyoshi
authors.forename: M
authors.initials: M
authors.lastname: Hashimoto
authors.forename: K
authors.initials: K
authors.lastname: Toba
authors.forename: H
authors.initials: H
authors.lastname: Orimo
authors.forename: Y
authors.initials: Y
authors.lastname: Ouchi
mesh_terms: D000818:Animals; D001011:Aorta / Q000473:pathology; D001161:Arteriosclerosis / Q000097:blood / Q000188:drug therapy* / Q000209:etiology*; D001794:Blood Pressure / Q000187:drug effects; D001835:Body Weight / Q000187:drug effects; D002784:Cholesterol / Q000008:administration & dosage* / Q000009:adverse effects* / Q000097:blood; D003324:Coronary Artery Disease / Q000209:etiology; D004036:Diet, Atherogenic; D004967:Estrogens / Q000494:pharmacology*; D005260:Female; D009566:Nitrates / Q000097:blood*; D009573:Nitrites / Q000097:blood*; D010052:Ovariectomy; D011817:Rabbits
chemical_list: D004967:Estrogens; D009566:Nitrates; D009573:Nitrites; D002784:Cholesterol