Estrogen regulates energy output, appetite and body weight, and insufficient estrogen receptors in certain regions of the brain may lead to obesity, according to a recent mouse study at the University of Texas Southwestern Medical Center.

“Estrogen has a profound effect on metabolism,” said Dr. Deborah Clegg, associate professor of internal medicine and senior author of the study. “We hadn’t previously thought of sex hormones as being critical regulators of food intake and body weight.”

The research is the first to demonstrate that estrogen works through two hypothalamic neural centers in the brain to regulate hunger and energy expenditure, keeping female body weight in check.

Female mice without the estrogen receptor alpha – a molecule that sends estrogen signals to neurons – in those parts of the brain became obese and developed related diseases, such as diabetes and heart disease.

These results were not replicated in male mice, although scientists believe other unknown estrogen receptor sites in the brain play a similar role in regulating male metabolism as well.

Although estrogen receptors are located throughout the body, researchers pinpointed two specific populations of estrogen receptors that seem to regulate energy balance for female mice.

The findings may be significant for postmenopausal women, many of whom have opted against hormonal replacement therapy. The research could lead to new types of hormonal replacement therapies in which estrogen is delivered to specific parts of the brain that regulate body weight. This would avoid the risks linked to full-body estrogen delivery, including breast cancer and stroke.

Physicians no longer routinely recommend long-term estrogen therapy for menopausal women. A Women’s Health Initiative study in 2002 proved the hormone 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 timing 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.”

The study is published in Cell Metabolism.

Source: University of Texas Southwestern Medical Center