Rodent of the week: When mice overeat

Overeating not only makes your body expand, it sends your brain off-kilter, say the authors of a new study on obesity. The study, from researchers at the University of Wisconsin-Madison, showed that a part of the brain that is normally dormant can be activated by too many calories.

Previous research has shown that over-nutrition causes an inflammatory response in many tissues in the body. This inflammation can lead to diseases like diabetes. A particular molecular compound called IKKbeta/NK-kappaB is known to promote this inflammation. But by giving mice loads of sugar or fat, the same molecular compound was activated in their brains. That, in turn, caused dysfunctions in the way they handled nutrition, such as changes in the important metabolic hormones insulin and leptin. Insulin lowers blood sugar while leptin controls appetite.

Researchers think that this normally inactive pathway in the brain may have been important in our evolutionary past, perhaps by boosting the body's immunity. But it's definitely something modern-day humans want to avoid. So go easy on that never-ending pasta bowl.

"In today's society, this pathway is mobilized by a different environmental challenge -- over-nutrition," said Dongsheng Cai, the lead author of the study. "The pathway leads to a number of dysfunctions."

The study also found that treatments that prevent the activity of IKKbeta/NF-kappaB in the animals' brains protected them from obesity. Scientists now hope they can create treatments to block this pathway in humans. The study was published in the journal Cell.

-- Shari Roan