Effects of a Soluble Fraction of Soybean on Lipid Profiles in Ovariectomized Rats Fed a Cholesterolemic Diet

Abstract

The increases in serum lipid profiles at the onset of menopause are regarded as a risk factor for cardiovascular disease. This study was designed to clarify the effects of a dried aqueous soybean extract and ovariectomy on lipid parameters in rats fed with cholesterolemic diet. Twenty-four 9-week-old female Sprague-Dawley rats were divided into two groups of 12 each and either sham-operated or ovariectomized. The ovariectomized and sham groups were then subdivided into groups of six and fed a semipurified casein-based diet (control diet) or the same diet containing dried soybean extract (0.5%) at the expense of sucrose (experimental diet). Total isoflavone content was 4.52 mg/g of soy extract. Ovariectomized groups showed significantly greater weight gain and food intake than sham groups, while uterus weight was markedly lower in ovariectomized groups. Although ovariectomy significantly increased the concentration of serum triacylglycerol, the concentration of serum total cholesterol was not affected by the operation. Soybean extract restored the concentration of serum triacylglycerol in the ovariectomized groups to the level observed in the sham groups. On the other hand, liver cholesterol levels were significantly higher in the ovariectomized groups compared to the sham group, without effects of the diet. This study suggests that soybean extract supplementation modulates the level of serum triacylglycerol induced by ovariectomy in rats, and furthers the possibility that dietary cholesterol may be a crucial factor in determining liver cholesterol in the presence of ovarian hormone deficiency.

Effects of treadmill exercise training on liver fat accumulation and estrogen receptor alpha expression in intact and ovariectomized rats with or without estrogen replacement treatment

“…Obesity easily leads to disorder of serum lipids (Durstine and Thomson 2001;Lee et al 2007). At present, the reports on the effects of exercise training on serum lipids disorder in OVX rats are not consistent.…”

Serum cholesterol and expression of ApoAI, LXRβ and SREBP2 in vitamin D receptor knock-out mice

“…Cholesterol changes in postmenopausal women [54] and in rodents after ovariectomy [55,56] are due to a lack of estrogen. Kamei et al [57] identified changes of gene expression in lipid metabolism including a decrease of SREBP1 in ovariectomized mice.…”

Animal Models for the Study of the Relationships between Diet and Obesity: A Focus on Dietary Protein and Estrogen Deficiency

“…It has been shown that supplementation with water-insoluble fish protein has a cholesterol lowering effect in ovariectomized rats (121). Another dietary protein source, that is soybean extract, has been found to modulate the level of serum TGs in ovariectomized rats fed a cholesterolemic diet (122). …”