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.