Lipid Metabolic Studies in Oophorectomized Women: Effects Induced by Two Different Estrogens on Serum Lipids and Lipoproteins

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Abstract
Oophorectomized women (11) (mean age 34.5 .+-. 5.9) were given 17-C-alkylated ethynyl estradiol (EE) 20 .mu.g/day and the non-alkylated estrogen, estradiol valerianate (E2V) 2 mg/day for 6 wk in separate periods preceded by 6 wk without hormonal replacement therapy. Blood samples were drawn before and after 6 wk on each estrogen. Serum phospholipids, cholesterol and triglycerides were assessed. Preparative ultracentrifugation with the isolation of the very low density (VLDL; d [density] < 1.006 g/ml); the low density (LDL; d = 1.006-1.063 g/ml) and the high density lipoprotein (HDL; d > 1.063 g/ml) fraction was performed. In the 3 lipoprotein fractions, phospholipid, total cholesterol, free cholesterol and triglycerides were determined. An oral glucose tolerance test with concomitant plasma insulin determinations was performed. EE caused an increase in total serum and LDL triglycerides; there was a reduction of triglycerides in serum and in VLDL and LDL with E2V. There was a positive correlation between plasma insulin values during oral glucose tolerance test and serum and VLDL triglycerides when E2V was administered. This apparently supports studies indicating that insulin (or rather the insulin-glucagon relationship) influences the hepatic triglyceride production rate. EE and E2V increased HDL cholesterol but E2V did not induce a concomitant increase in serum triglycerides which would suggest a more physiological effect from the latter compound since fertile females have lower serum triglycerides and higher HDL cholesterol levels than males of corresponding age. The same differences are true in a comparison between fertile and postmenopausal women. Implications for atherogenesis are discussed.