Effect of estrogen replacement therapy in the early phase on atherosclerosis in rats

Objective:To understand the effect of estrogen replacement therapy(ERT) in the early phase on atherosclerosis in rats fed by high fat diet.Methods:28 rats were divided into 4 groups:group A(sham operation),group B(ovariectomized without estradiol),group C(ovariectomized with low-dose estradiol) and group D(ovariectomized with high-dose estradiol).All the rat in 4 groups were given 1% cholesterol diet for 12 weeks,the levels of blood lipids,estradiol and serum superoxide dismutase(SOD) activity were detected before the operation and on the fourth and twelfth weeks.Results:After 12 weeks,the level of estradiol in group B was significantly lower than that in group A(P0.05),the level of estradiol in group D was significantly higher than that in group A(P0.05),there was no difference in the level of estradiol between group C and group A(P0.05);the levels of TC and LDL-C in group B were significantly higher than those in group A(P0.05);the levels of TC and LDL-C in group C and group D were significantly lower than those in group A(P0.05),and levels of TC and LDL-C in group B were the lowest among four groups.The aortic plaque area in group B was the largest among four groups(P0.05),the aortic plaque areas in group C and group D were smaller than that in group A(P0.05).The serum SOD activity of group B decreased significantly.Conclusion:Estrogen replacement therapy in the early phase can improve the metabolism of the serum lipids,increase the SOD activity and inhibit the formation of atherosclerosis.