US researchers find falling estrogen levels in women can lead to muscle loss
A study from the University of Minnesota Medical School (UMN-Med) in Minneapolis has recently established that estrogen is essential in females for maintaining muscle stem cell health and function. The associated animal study showed that a lack of estrogen or genetic deletion of the estrogen receptor in muscle stem cells led to a 30 to 60% drop in muscle stem cell (satellite cell) numbers across at least five different muscles.
Using mice whose ovaries had been surgically removed as well as mice without the estrogen receptor in their satellite cells, the UMN-Med researchers evaluated these muscles’ ability to regenerate – here, the surviving satellite cells had severe difficulty reproducing themselves and generating new muscle after injury.
In addition, a subsequent collaboration with Finnish scientists, who performed muscle biopsies in women shortly before and after the transition to menopause, showed that the number of satellite cells correlated strongly with changing serum estrogen levels in females.
“It has long been known that male sex hormones promote muscle health, but we have been in the dark about what happens when females age,” said Dawn Lowe, a Professor in the Department of Rehabilitation Medicine at UMN-Med.
“This is the first work to show that estrogen deficiency affects the number as well as the function of satellite cells,” Lowe added.
While estrogen replacement therapy can help maintain muscle health, it also raises the risk of cancer due to estrogen’s effects on tissues of the breast and endometrium. However, the researchers found a new class of drug that appears not to affect breast or endometrial tissue; it could otherwise stimulate estrogen signals in satellite cells and protect aging women from muscle stem cell decline due to menopause, without the risks associated with conventional hormone replacement therapy.
