The harmful effects of synthetic progestin
kofi at anon.un
Sat Dec 13 22:19:10 EST 2003
University Of South Florida Health Sciences Center
Synthetic Progestin Damages, Estrogen Protects Blood Vessels In Animal
TAMPA (11 Dec 2003) -- Synthetic progestins may be the major cause of
harmful side effects reported with hormone replacement therapy.
University of South Florida researchers used a novel imaging technique
to show that progestins caused toxicity while natural progesterone and
estrogen did not show toxicity to blood vessels in live animals.
"Our findings can lead to the development and screening of synthetic
hormones to find a safe progestin that will ultimately give women safer
options than are currently available for hormone replacement therapy,"
said Tom Thomas, MD, PhD, co-principal investigator and lead author of
the study published today in Climacteric, the Journal of the
International Menopause Society.
"This is experimental evidence that supports scientists who believe
estrogen with the right formulation is good for some women, depending on
their other risk factors."
The novel imaging technique was developed by Thomas and Johannes Rhodin,
MD, PhD, co-principal investigator. It took three years for Thomas and
Rhodin to combine video microscopy with fluorescence and electron
microscopy. By labeling blood cells with a fluorescent tag, the team
observed blood flow, blood vessel structure and activities of various
blood cells in real time in a live animal. After one dose of medroxy
progesterone acetate (MPA), the most widely used synthetic progestin in
estrogen prepaparations and oral contraceptives, the rats had visible
damage to the periphery and brain blood vessels, endothelial and smooth
muscle damage, inflammation and blood clot formation and impeded blood
These vascular reactions to synthetic progestin can lead to increases in
heart attacks, blood clots, strokes and dementia--problems that were
observed in the Women's Health Initiative," Thomas said.
The USF researchers' findings may shed light on the current reassessment
of the National Institute of Health-sponsored Women's Health Initiative.
Using the same video microscopic techniques the research team found that
either estrogen alone or the natural progesterone did not cause such
vascular toxicity. They also showed that estrogen protects blood vessels
of the brain and surrounding areas and prevents inflammation and clot
In a related study the team showed that estrogen might protect blood
vessels in the brain from beta-amyloid, a key factor contributing to
memory loss in Alzheimer's disease. The article "In vivo cerebrovascular
actions of amyloid B-peptides and the protective effect of conjugated
estrogens" is published in the current issue of the Journal of
Alzheimer's Disease 5 (2003).
This supports recommendations to use estrogen early and in low doses to
protect the brain," Dr. Thomas said.
This story has been adapted from a news release issued by University Of
South Florida Health Sciences Center.
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