The harmful effects of synthetic progestin

kofi 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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