Antiatherogenic Effect of Isoflavones in Ovariectomized Apolipoprotein E-Deficient Mice

Abstract

The consumption of isoflavone-containing foods such as soybean and soybean products has been reported to have beneficial effects on the cardiovascular system in postmenopausal women. The present study was carried out to examine the mechanism underlying the beneficial effects of isoflavones in apolipoprotein (apo) E-deficient mice subjected to ovarian resection. Compared with sham-operated mice, ovariectomized mice had a larger arterial lesion area in the aortic root. Feeding the ovariectomized mice an isoflavone-containing diet (0.055 mg/kJ of total isoflavones/cal of diet) reduced the size of these lesions more than did feeding them with an isoflavone-free diet. Neither ovariectomy nor diet had a significant effect on the concentration of cholesterol in serum and urinary levels of isoprostanes, which are biomarkers for oxidative stress in vivo. The ovariectomized mice showed a greater increase in mRNA abundance for monocyte chemoattractant protein (MCP)-I in the aorta and in the level of nitric oxide (NO) secreted by peritoneal macrophages in culture than did the sham-operated mice. The isoflavone-containing diet lowered the MCP-I expression and the NO secretion more than did the isoflavone-free diet. These results suggest that dietary isoflavones confer an antiatherogenic effect by preventing the activation of macrophages due to the removal of ovaries.

Diet and Atherosclerosis in Apolipoprotein E-Deficient Mice

“…We examined the mechanism underlying the beneficial effects of isoflavones in apoEÀ/À mice subjected to ovarian resection. 135) Compared with sham-operated mice, the ovariectomized mice had larger arterial lesion areas in the aortic root. Feeding the ovariectomized mice an isoflavone-containing diet (0.055 mg/kJ of total isoflavones/cal of diet) reduced the sizes of these lesions more than did feeding them an isoflavone-free diet.…”

Dietary Pine Bark Extract Reduces Atherosclerotic Lesion Development in Male ApoE-Deficient Mice by Lowering the Serum Cholesterol Level

“…26) This preceding work indicates a beneficial effect of estrogen on the development of atherosclerosis. In contrast, it has been reported that estrogen accelerates breast cancer, 27) and that proanthocyanidins derived from grapes exert a beneficial effect on breast cancer by suppressing the synthesis of estrogen by inhibiting aromatase activity.…”

The effects of dietary linoleic acid on reducing serum cholesterol and atherosclerosis development are nullified by a high-cholesterol diet in male and female apoE-deficient mice

“…17β-estradiol treatment has been shown to suppress MCP-1 protein and gene expression in ovariectomised (OVX) rabbits (32) , and oestrogen treatment has been found to attenuate vascular re-modelling by promoting the synthesis of MCP-1 mRNA in endothelial cells (33) . Moreover, it has been demonstrated that oestrogen reduces MCP-1 mRNA levels in female OVX apoE -/ -mice, thereby preventing the development of atherosclerosis (34) . On the basis of the foregoing discussion, it is thus reasonable to assume that high-dietary cholesterol of LAHC diets does not aggravate the aortic inflammatory response in either male or female ApoE -/ -mice, although there may be differences in the underlying mechanisms.…”