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Role for estrogen in bone marrow

 

 
Scientists have discovered that estradiol triggers the formation of blood platelet cells. Blood is composed of 3 cell types: red blood cells, white blood cells, and platelets. Platelets circulate in the bloodstream to facilitate clotting and halt bleeding. They are derived from a specialized bone marrow cell called a megakaryocyte. A mature megakaryocyte extends long cytoplasmic processes (termed proplatelets) from its cell surface that, which simultaneously fragment into thousands of new platelet cells.

The 3b-HSD gene is normally turned-on by p45 NF-E2, and encodes an enzyme that regulates all steroid hormone biosynthesis. 3b-HSD induces the production of estrogen, in the form of estradiol, in both male and female megakaryocyte cells. It was found that the addition of exogenous estradiol increased proplatlet formation by more than fifty percent, while the inhibition of estradiol receptors blocked proplatelet formation in live mice.

This could mean that patients suffering from low platelet counts, such as those with anemia, bone marrow abnormalities, or undergoing chemotherapy, may benefit from the administration of estradiol and/or a 3b-HSD activator, as an alternative to blood transfusions to increase platelet levels.

Conversely, patients with abnormally high platelet counts, who are prone to forming clots and therefore at an increased risk for strokes, heart attacks, or even miscarriage (ie. from placental clots) would be candidates for drugs designed to specifically block 3b-HSD or estradiol receptors to effectively normalize their platelet levels.

Bibliography

Yuka Nagata, Jun Yoshikawa, Atsushi Hashimoto, Masayuki Yamamoto, Anita H. Payne, Kazuo Todokoro (2003) Proplatelet formation of megakaryocytes is triggered by autocrine-synthesized estradiol Genes and Development, 17:2864-2869 http://www.eurekalert.org/pub_releases/2003-11/cshl-sun112003.php
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Citation
Bland.J., (2003) About Gender: Role for estrogen in bone marrow
http://www.gender.org.uk/about/06encrn/62_marow.htm
 
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Web page copyright Derby TV/TS Group. Text copyright Jed Bland.
Last amended 31.12.03