Estrogen replacement therapy decreases platelet-activating factor-acetylhydrolase activity in post-menopausal women.
OBJECTIVE
To examine the effects of estrogen replacement therapy on plasma platelet-activating factor-acetylhydrolase (PAF-AH) activity and the lipoprotein profile in post-menopausal women.


METHODS
Eight post-menopausal women received conjugated equine estrogen (0.625 mg/day) orally for a period of 10 weeks. PAF-AH activity and lipid levels were measured in plasma samples obtained from each subject prior to treatment and after 2, 6, and 10 weeks of estrogen therapy.


RESULTS
Within 2 weeks of initiating estrogen treatment, a significant reduction in PAF-AH activity (-26%) was observed. Estrogen also caused significant decreases in total cholesterol (-8%), low-density lipoprotein-cholesterol (-24%), and the ratio of apolipoprotein B to A-II (-19%). On the other hand, levels of both high-density lipoprotein-cholesterol (18%) and triglyceride (31%) were elevated.


CONCLUSIONS
Estrogen exerts a favorable effect on the lipoprotein profile, but decreased plasma PAF-AH activity may facilitate platelet aggregation thereby opposing protective effect of estrogen-replacement therapy with respect to thrombotic complications.
Yoshimura
T
T
Department of Obstetrics and Gynecology, Kumamoto University School of Medicine, Japan. yoshimur@kaiju.medic.kumamoto-u.ac.jp
Ohshige
A
A
Maeda
T
T
Ito
M
M
Okamura
H
H
D043203:1-Alkyl-2-acetylglycerophosphocholine Esterase; D015914:Estrogen Replacement Therapy; D004966:Estrogens, Conjugated (USP) / Q000494:pharmacology*; D005260:Female; D006801:Humans; D008055:Lipids / Q000097:blood; D008074:Lipoproteins / Q000097:blood; D008875:Middle Aged; D010741:Phospholipases A / Q000378:metabolism*; D010972:Platelet Activating Factor / Q000378:metabolism*; D010974:Platelet Aggregation; D010976:Platelet Count; D017698:Postmenopause / Q000097:blood / Q000187:drug effects*; D013997:Time Factors
D004966:Estrogens, Conjugated (USP); D008055:Lipids; D008074:Lipoproteins; D010972:Platelet Activating Factor; D010741:Phospholipases A; D043203:1-Alkyl-2-acetylglycerophosphocholine Esterase