A recent UT Southwestern Medical Center study found that estrogen（雌性激素） regulates energy expenditure1, appetite and body weight, while insufficient2 estrogen receptors in specific parts of the brain may lead to obesity3. "Estrogen has a profound effect on metabolism4（新陈代谢） ," said Dr. Deborah Clegg, associate professor of internal medicine and senior author of the study published Oct. 5 in Cell Metabolism. "We hadn't previously5 thought of sex hormones7 as being critical regulators of food intake8 and body weight."
The mouse study is the first to show that estrogen, acting9 through two hypothalamic（下丘脑的） neural10 centers in the brain, keeps female body weight in check by regulating hunger and energy expenditure. Female mice lacking estrogen receptor alpha -- a molecule11 that sends estrogen signals to neurons -- in those parts of the brain became obese12 and developed related diseases, such as diabetes13 and heart disease.
Similar results were not seen in male mice, although researchers suspect other unknown estrogen receptor sites in the brain play a similar role in regulating metabolism for males as well.
Estrogen receptors are located throughout the body, but researchers found two specific populations of estrogen receptors that appear to regulate energy balance for female mice.
The findings are potentially important for millions of postmenopausal（绝经后的） women, many of whom have decided14 against hormonal15 replacement16 therapy. The study could lead to new hormonal replacement therapies in which estrogen is delivered to specific parts of the brain that regulate body weight, thereby17 avoiding the risks associated with full-body estrogen delivery, such as breast cancer and stroke.
Doctors stopped routinely recommending long-term estrogen therapy for menopausal women in 2002 when a Women's Health Initiative study showed the hormone6 also led to increased risk of cardiovascular disease.
"The role of estrogen in postmenopausal women continues to remain uncertain," Dr. Clegg said. "Current research is focused on the timing18 and the type of estrogen supplementation that would be most beneficial to women. Our findings further support a role for estrogens in regulating body weight and energy expenditure, suggesting a benefit of estrogen supplementation in postmenopausal women."
Other UT Southwestern researchers involved in the study included lead author Dr. Yong Xu, a former postdoctoral researcher in Dr. Clegg's lab; Dr. Carol Elias, assistant professor of internal medicine; and Dr. Joel Elmquist, professor of internal medicine.
The research was supported by grants from the National Institutes of Health, the American Heart Association and the American Diabetes Association.
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