Combined oestrogen-progestogen replacement therapy does not inhibit low-density lipoprotein oxidation in postmenopausal women.
OBJECTIVE
The use of oestrogen containing hormone replacement therapy (HRT) is related to a significantly reduced atherosclerotic cardiovascular risk in postmenopausal women. Oestrogen is thought to be antioxidant and may inhibit low-density lipoprotein (LDL) oxidation in vitro. We investigated the effect of combined oestrogen and progestogen HRT on LDL oxidation in postmenopausal women.


METHODS
Eighteen healthy women were given oestrogen/progestogen, and the susceptibility of LDL to oxidation was measured as the level of autoantibody to oxidative modified LDL and the production of conjugated dienes during copper-dependent oxidation after 3 and 6 months HRT. The levels of vitamin E, the major antioxidant in LDL, were also measured.


RESULTS
After HRT, the anti-oxidatively modified LDL antibody level remained unchanged [1.58+/-0.16, 0.10 (-0.10, 0.26), and 0.08 (-0.09, 0.19), mean+/-s.d. at baseline, and mean change with 95% confidence intervals for differences at 3 and 6 months, respectively, P>0.05] as did the production of conjugated dienes when determined as lag phase [51.2+/-7.5, -0.3 (-3.9, 3.3), and 1.5 (-3.4, 6.4) min, P>0.05]. The LDL vitamin E content, measured as alpha-tocopherol, was also not altered [2.34+/-0.54, -0.07 (-0.27, 0.13), and -0.07 (-0.33, 0.16) nmol mg(-1) LDL, P>0.05] by treatment.


CONCLUSIONS
Combined oestrogen and progestogen therapy for 6 months in postmenopausal women does not protect LDL against oxidation.
Wen
Y
Y
Department of Therapeutics, Trinity Centre for Health Sciences, St James's Hospital, Dublin, Ireland.
Doyle
M C
MC
Norris
L A
LA
Sinnott
M M
MM
Cooke
T
T
Harrison
R F
RF
Feely
J
J
D002784:Cholesterol / Q000097:blood; D004359:Drug Therapy, Combination; D015914:Estrogen Replacement Therapy; D004967:Estrogens / Q000008:administration & dosage / Q000097:blood / Q000627:therapeutic use*; D005260:Female; D006801:Humans; D017270:Lipoprotein(a) / Q000097:blood / Q000187:drug effects; D008075:Lipoproteins, HDL / Q000097:blood / Q000187:drug effects; D008077:Lipoproteins, LDL / Q000097:blood / Q000187:drug effects* / Q000378:metabolism; D008875:Middle Aged; D010084:Oxidation-Reduction / Q000187:drug effects; D017698:Postmenopause / Q000097:blood / Q000187:drug effects*; D011372:Progestins / Q000008:administration & dosage / Q000627:therapeutic use*; D016896:Treatment Outcome; D014810:Vitamin E / Q000097:blood
D004967:Estrogens; D017270:Lipoprotein(a); D008075:Lipoproteins, HDL; D008077:Lipoproteins, LDL; D011372:Progestins; D014810:Vitamin E; D002784:Cholesterol