雌激素对大鼠血清脂蛋白和肝膜LDL受体的影响

THE EFFECT OF ESTROGEN ON SERUM LIPOPROTEINS AND HEPATIC MEMBRANE LDL RECEPTOR IN RATS

Wistar雄性大鼠30只随机分为E_2组和对照组,前者每日皮下注射苯甲酸雌二醇5mg/kg一周,血清TC,LDL-C,HDL-C及LDL-C/TC均显著降低,以LDL-C降低最为显著,HDL-C/TC,HDL-C/LDL-C,VLDL-C无明显改变。体外实验发现,大鼠肝膜与人^(125)I-LDL特异结合位点E_2组比对照组增加3～5倍。提示苯甲酸雌二醇降低LDL与肝脏LDL-受体增加密切相关。

30 male rats were divided into 2 groups with 15 rats each,the treatment(C+E_2)and the control(C)group.Animals were fed with thesame diet.The rats in(C+E_2)group received estradiol benzoate(5mg/kgbody weight/day)subcutaneously for 7 days.Human low density lipoprotein(LDL)(d=1.063)was prepared fromplasma by sequential ultracentrifugation and was labelled with ^(125)I usingwith some modification of the iodine monochloride method of McFarlane.The rat liver membranes(100000g pellet)were prepared by ultracentri-fugation,stored at -80℃,and were used within 2 weeks.The serumTC and Lp-C were determined by enzymatic method.The results indicated as follows:the serum TC,HDL-C,LDL-C andLDL-C/TC decreased significantly in treatment group,while the serumHDL-C/TC,HDL-C/LDL-C,VLDL-C/TC,and VLDL-C were unchanged.The binding of human ^(125)I-LDL to liver membranes from treated ratswas increased 3-to 5-fold.It was shown that hepatic LDL receptors inrat were stimulated by the estradiol benzoate.It is suggested that thelowering of plasma LDL is intimately associated with the elevation ofhepatic receptors.