Influence of estrogen replacement therapy on plasma lipid peroxidation.
OBJECTIVE
To observe whether any relationship exists between the concentration of plasma estradiol (E2) and the plasma concentrations of malondialdehyde (MDA) or whether a relationship exists between the concentration of plasma E2 and the activity of the erythrocyte enzymes, superoxide dismutase (SOD) and catalase, in ovariectomized female Wistar rats (treated and untreated with E2).


METHODS
We used 40 ovariectomized Wistar rats randomly assigned to four groups. The first group was allowed to evolve freely with no treatment. A gel containing 17beta-estradiol was administered transdermally to the other three groups at doses of 4, 8, and 16 microg/day, respectively. After 15 days of treatment, blood samples were obtained from the four groups. The concentrations of plasma MDA and E2 and the activities of erythrocyte catalase and SOD were determined.


RESULTS
There were significant correlations between the MDA levels and the logarithm (base 10) of the plasma E2 concentrations in both linear (p = 0.00093) and quadratic (p = 0.000001) regression analyses. No relationship was found between the E2 concentrations and the catalase and SOD activities.


CONCLUSIONS
There was a clear relationship between the plasma levels of MDA and the logarithm of the plasma E2 concentrations, which was best demonstrated with a quadratic regression. This model may explain the contradictory findings presented by estrogens with respect to their pro-or antioxidant action.
Gómez-Zubeldia
M A
MA
Department of Nursing, School of Medicine, University of Extremadura, Badajoz, Spain.
Arbués
J J
JJ
Hinchado
G
G
Nogales
A G
AG
Millán
J C
JC
D000818:Animals; D002374:Catalase / Q000187:drug effects; D004353:Drug Evaluation, Preclinical; D004912:Erythrocytes / Q000187:drug effects / Q000201:enzymology; D004958:Estradiol / Q000494:pharmacology / Q000627:therapeutic use*; D015914:Estrogen Replacement Therapy; D004967:Estrogens / Q000097:blood; D005260:Female; D015227:Lipid Peroxidation / Q000187:drug effects*; D008315:Malondialdehyde / Q000097:blood*; D010052:Ovariectomy; D017698:Postmenopause / Q000187:drug effects* / Q000378:metabolism*; D011897:Random Allocation; D051381:Rats; D017208:Rats, Wistar; D012044:Regression Analysis; D013482:Superoxide Dismutase / Q000187:drug effects; D013997:Time Factors
D004967:Estrogens; D004958:Estradiol; D008315:Malondialdehyde; D002374:Catalase; D013482:Superoxide Dismutase