Lipoprotein, apolipoprotein, and lipolytic enzyme changes following estrogen administration in postmenopausal women.

To test whether estrogen can modulate the cholester- olemic response to an Occidental diet, six healthy postmeno- pausal women were studied for 84 days while ingesting a solid food diet of constant composition high in cholesterol content (995 mg/d). In the middle of the study, estrogen (17~-ethinyl es- tradio1,l pg/kg per day) was administered orally. Ingestion of the diet for the initial 28 days did not alter lipoprotein lipid or apo- lipoprotein (apo) levels. However, with just 4 days of estrogen use there were significant decreases in apoE ( - 36 %), low densi- ty lipoprotein cholesterol (- 26%), and postheparin plasma hepatic triglyceride lipase activity (HTGL) ( - 61 %), and an in- crease in high density lipoprotein (HDL) triglyceride (72 %). These changes persisted throughout the estrogen use. The per- cent change in HTGL with 4 days of estrogen correlated inverse- ly with the percent change in HDL triglyceride (rs = -0.94). After 28 days of estrogen there were also significant increases in HDL cholesterol (21 %), HDL2 cholesterol (42 %), apoA-I (37 %), and apoA-II(9 %), and a decrease in apoB ( - 11 %). The level of apoE at this juncture correlated inversely with the level of.HDL cholesterol (r, = - 0.90), and the levels of HTGL and apoA-I correlated with HDL2 cholesterol (r, = - 0.89 and r, = 0.89, respectively). M Thus, HTGL may play a role in both the early estrogen-related changes in HDL triglyceride and apoE and the late estrogen-related changes in HDL cholesterol, apoA-I, and apoA-11. - Applebaum-Bowden, D., P. McLean, A. Steinmetz, D. Fontana, C. Matthys, G. R. Warnick, M. Cheung, J. J. Albers, and W. R. Hazsard. Lipoprotein, apo- lipoprotein, and lipolytic enzyme changes following estrogen ad- ministration in postmenopausal women. J Lipid Res. 1989. 30: 1895-1906.