July 20, 2005 UC Irvine School of Medicine researchers have identified how estrogen helps prevent a cardiac ailment often seen in women who have heart attacks. This research provides further evidence that hormone replacement therapy after menopause can help prevent certain forms of cardiovascular disease in women.
In tests done on female mice and mice heart cells, Dr. Ellis R. Levin and his UCI colleagues found that estrogen triggers molecular activity that blocks cardiac hypertrophy, or heart enlargement. This thickening of tissue in the heart ventricles is seen in almost 80 percent of people following heart attacks. Cardiac hypertrophy also commonly results from long-standing hypertension and leads to a poorly functioning heart and heart failure in many instances. Previous studies have indicated that premenopausal women have lower rates of heart disease than men, a rate that significantly rises in women after menopause.
Study results appear in the July 15 issue of the Journal of Biological Chemistry.
The results will continue a debate raised by the Women’s Health Initiative over whether estrogen plays any beneficial role with cardiac disease in women. The initiative is a recently completed 15-year research program funded by the National Institutes of Health to address the most common causes of death, disability and poor quality of life in postmenopausal women, and some of its study data indicated that estrogen offered no protection against the development of arteriosclerotic heart disease. A recent article published in Science by Drs. Michael Mendelsohn and Richard Karas of Tufts University School of Medicine, however, addressed concerns of drawing conclusions based on the Women’s Health Initiative data.
“There has been intense reaction to the Women’s Health Initiative report indicating that estrogen is not beneficial in preventing coronary heart disease,” said Levin, a professor of medicine, biochemistry and pharmacology, and director of endocrinology at UCI and the affiliated Veterans Affairs Medical Center in Long Beach, Calif. “Our work suggests that further in-depth studies should be undertaken to determine if estrogen supplements prevent cardiac hypertrophy, especially in postmenopausal women with risk factors for this disorder. Existing research results in women support this concept.”
Estrogen is needed for normal growth and development of female sex organs and for functions such as bearing children. But during menopause, the body’s production of estrogen decreases. Estrogen replacement is used for symptoms associated with menopause and for the prevention of osteoporosis in postmenopausal women. Estrogen supplements, though, have been linked to higher rates of breast cancer.
This study follows another published in the Journal of Biological Chemistry earlier this year, in which the laboratories of Levin and Ghassan Kassab, professor of biomedical engineering at UCI, showed that estrogen causes dilation of the arteries in female mice. Such an effect could compensate for the damaging effects of hypertension on blood vessels.
Mahnaz Razandi, Ali Pedram and Mark Aitkenhead of UCI assisted with the study. The Department of Veterans Affairs and the National Institutes of Health provided support.
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