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Abstract
Thirty healthy postmenopausal women were randomized into 2 groups that received a
sequential combined hormone-replacement therapy (HRT) (n = 18; conjugated equine estrogen
0.625 mg/d for 28 days and 5 mg of medroxyprogesterone acetate during the last 14
days) or placebo (n = 12). Plasma samples were collected before and during treatment
(days 0, 15, 43, 71). High-density lipoprotein (HDL) lipid content, lipoprotein (Lp)A-I
and LpA-I:LpA-II concentration, lecithin:cholesterol acyl transferase activity (LCAT),
phospholipid transfer protein (PLTP) activity, and the plasma capacity to carry out
cholesterol efflux from Fu5AH cells were measured. Most significant changes were found
within the first 15 days after HRT. After 71 days of HRT, we found an increase in
LpA-I lipoparticles (27%) and the following HDL lipids: phospholipids (21%), triglycerides
(45%), and free cholesterol (43%), as well as an increase in cholesterol efflux (12.5%).
PLTP activity, on the other hand, decreased 21% after 71 days of treatment. No significant
changes in LCAT activity, HDL-cholesterol ester or LpA-I:LpA-II particles were found.
Positive correlation between cholesterol efflux and the variables LpA-I and HDL-phospholipids
were observed. PLTP was negatively correlated with apolipoprotein (apo) A-I, LpA-I,
and LpA-I:LpA-II. In summary, our study, performed during 3 hormonal cycles, shows
that HRT not only modifies HDL-cholesterol level, but also its lipid composition and
HDL lipoparticle distribution. HRT enhances the plasma capacity to carry out cholesterol
efflux from the Fu5AH system and decreases the activity of PLTP, a key protein regulating
HDL levels. Considering the protocol sampling, these results represent mainly the
estrogenic effect of HRT.
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Footnotes
☆Supported by grants INSERM/CONICYT No. 1997-0042 and DIU No. 99.072.021-1 from Universidad de Concepci[oacute]n.
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Copyright
© 2002 Published by Elsevier Inc. All rights reserved.
