Effects of estrogen and medroxyprogesterone acetate on subpopulations of triglyceride-rich lipoproteins and high-density lipoproteins.
Hormonal replacement therapy (HRT) in postmenopausal women has been shown to increase both triglyceride (TG) and high-density lipoprotein (HDL) cholesterol levels. To better understand the effects of conjugated equine estrogen (CEE) and medroxyprogesterone acetate (MPA), the 2 most commonly prescribed hormones in HRT, on the different subpopulations of TG-rich and HDL lipoproteins, we conducted a placebo-controlled, double-blind, randomized, crossover study consisting of 3 different phases in 14 postmenopausal women. The 3 phases, each 8-week long, included: (1) placebo, (2) CEE 0.625 mg/d, and (3) CEE 0.625 mg/d and MPA 2.5 mg/d. Slight and statistically nonsignificant elevations in TG levels were observed during the CEE treatment. While very-low-density lipoprotein (VLDL) cholesterol levels were not significantly affected by CEE and CEE + MPA, both HRT treatments lowered remnant lipoprotein (RLP) cholesterol (-14% and -37%, respectively). Compared with placebo, CEE caused a significant increase in HDL, HDL(2), apolipoprotein (apo) A-I, LpAI, alpha1, and prealpha1 levels (12%, 27%, 17%, 26%, 60%, and 102%, respectively). The combination therapy blunted the CEE effect on all HDL parameters, resulting in HDL, HDL(2), and LpAI levels being no longer significantly different from placebo. Apo A-I levels and alpha1, and prealpha1 levels were still significantly higher than placebo (+11%, +50%, and +112%, respectively). These results indicate that HRT has beneficial effects on RLP levels and that, while the estrogen component of HRT has a beneficial effect on the HDL subpopulations mostly associated with coronary heart disease (CHD) protection, MPA partially inhibits this effect.
Lamon-Fava
Stefania
S
Lipid Metabolism Laboratory and the Biostatistics Unit, Jean Mayer USDA Human Nutrition Research Center on Aging, Tufts University, Boston, MA 02111, USA.
Posfai
Borbala
B
Asztalos
Bela F
BF
Horvath
Katalin V
KV
Dallal
Gerard E
GE
Schaefer
Ernst J
EJ
D000368:Aged; D001053:Apolipoproteins / Q000097:blood; D018592:Cross-Over Studies; D004311:Double-Blind Method; D015914:Estrogen Replacement Therapy; D004966:Estrogens, Conjugated (USP) / Q000008:administration & dosage / Q000494:pharmacology*; D005260:Female; D006801:Humans; D008074:Lipoproteins / Q000097:blood* / Q000187:drug effects; D008075:Lipoproteins, HDL / Q000097:blood* / Q000187:drug effects; D017258:Medroxyprogesterone Acetate / Q000008:administration & dosage / Q000494:pharmacology*; D008875:Middle Aged; D012016:Reference Values; D016896:Treatment Outcome; D014280:Triglycerides / Q000097:blood*
D001053:Apolipoproteins; D004966:Estrogens, Conjugated (USP); D008074:Lipoproteins; D008075:Lipoproteins, HDL; D014280:Triglycerides; D017258:Medroxyprogesterone Acetate