Transdermal estrogens do not appear to modify the extent of lesional areas of aortic atherosclerosis in oophorectomized rabbits on a cholesterol-rich diet.

Cardiovascular disease (CVD) is the leading cause of death in older women in industrialised countries. It has been suggested that it is the cessation of estrogen production by the ovaries that puts postmenopausal women at increased risk of CVD. Estrogen therapy has demonstrated a protective effect against CVD and several reports suggest that diverse mechanisms may be involved. Oral estrogen appears to be associated with a better lipid profile than the use of transdermal estrogens; however, it is assumed that estrogens, oral and non-oral, have direct actions on the blood vessels that may exert an important role in cardiovascular disease prevention. To investigate the effect of transdermal estrogen therapy on aorta atherogenesis, we studied 20 cholesterol-fed New Zealand White rabbits for 4 months. The rabbits were oophorectomized and randomly assigned to two groups. Ten rabbits underwent bilateral ovariectomy followed by treatment with transdermal 17-beta-estradiol (group E) and the other 10 received placebo after sterilization (Group C). After diet total levels of cholesterol increase in group C from 50. 0+/-12.5 to 820.9+/-186.0 mg/dl, and in group E from 52.6+/-9.4 to 811.4+/-213.0 mg/dl (no significant differences were observed between groups). Estrogen therapy increased twofold the total reactive antioxidant potential (TRAP group C: 22.5+/-16.7 mmol of Trolox/l vs. TRAP group E: 43.4+/-22.4 mmol of Trolox/l; P<0.04). At 4 months, the cholesterol-rich diet caused atherosclerotic lesions in both treated and untreated rabbits affecting 18.7+/-14.5 and 21. 6+/-9.7% of the aortic surface respectively. In summary, the principal result from this study was that although treatment with transdermal 17-beta-estradiol in cholesterol-fed ovariectomized rabbits increases the TRAP to pre-surgery values, it does not inhibit aortic cholesterol accumulation.