The researchers also found that female mice that lacked the hormone receptors in POMC neurons had difficulty reproducing and produced smaller litters than mice lacking just one of the receptors. This is due in part to the fact that the females lacking both receptors had extremely high levels of androgens, the researchers speculate. The most well-known androgen is the male sex hormone testosterone.

"Reproductive endocrinology isn't my area of expertise, but these findings were nonetheless completely unexpected," Dr. Elmquist said. "We believe this may be one of the first genetic models of polycystic ovary syndrome."

Polycystic ovary syndrome, or PCOS, is a metabolic disorder characterized by abnormal hormone levels. It is often associated with a wide range of afflictions in women, ranging from obesity and excessive facial hair to more severe disorders, such as infertility, diabetes and heart disease.

Dr. Elmquist said one of his goals is to understand better how these hypothalamic POMC neurons control glucose production in the liver.

The study is also part of UT Southwestern's Task Force for Obesity Research. In 2007, the multidisciplinary group received a $22 million grant from the National Institutes of Health to enhance its efforts to attack obesity from every angle. The award is one of nine interdisciplinary research consortia sponsored by the NIH Roadmap for Medical Research, a series of initiatives designed to transform the nation's medical research capabilities. The UT Southwestern group is the only one focused on obesity.

Source: UT Southwestern Medical Center