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February 2008 Issue

Physician-scientist Silvana Obici, MD, sees the brain’s actions as the foundation for understanding obesity.
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Scientist Says Obesity Research Starts With the Mechanics of the Brain

Published February 2008

Obesity researchers use many hypotheses and approaches to study weight gain, but ultimately, their work can be narrowed to the same basic question: If two people are given the same diet, why does one person stay thin, while the other gains weight?

Silvana Obici, MD, asks that question everyday.

An associate professor and scientist in UC’s Obesity Research Center, Obici is also an endocrinologist who teaches medical students and residents as she sees patients in the endocrine clinic. She knows well the intricate science behind obesity, and regularly interacts with people struggling with their weight.

A member of the psychiatry department faculty, Obici has a strong interest in the brain’s role in regulating body weight.

“The brain senses the presence of nutrients and then adjusts metabolism accordingly to maintain body weight,” she says.

But the brain doesn’t do all the work. Nutrients are an important player in this communication loop, says Obici, because they use hormones to announce their arrival in the gut.

“They signal to the brain when they have entered the body and when they are there in abundance,” she says.

Particular types of nutrients might play specific roles in the weight regulation cycle. Even the “bad” nutrients—the ones people have been advised to stay away from—might not necessarily be so bad after all, Obici says.

“Nutrients that we’re commonly told to avoid may be bad in terms of palatability and composition, but could play a key role in the gut-brain interaction that helps us to regulate weight,” she says.

Obici adds that many people who are predisposed to gain weight could have a disruption in the mechanism for sensing certain nutrients in the body.

“Perhaps in obese people,” she says, “the brain isn’t functioning as it should.”

This theory becomes even more exciting to Obici as she discusses studies she’s done on a type of medication used to treat psychiatric disorders.

A class of atypical antipsychotics targeting specific neurotransmitters in the brain increases the incidence of diabetes and obesity in about 30 percent of its users.

The strong association of this medication to possibly harmful health effects makes its use less practical, but gives researchers a place to start as they look to the brain for clues about obesity.

In Obici’s laboratory studies, the medication causes glucose levels to increase in a matter of minutes.

“Tinkering with a neurotransmitter, we’ve found, has an immediate effect on the brain’s ability to control metabolism in other parts of the body,” says Obici. “It’s a concept that’s often overlooked.”

Although the medication she’s studying does the exact opposite of what she’d ultimately like an obesity therapeutic to do, Obici sees its actions as a window into understanding how the brain controls metabolism in the liver, muscles and pancreas.

The knowledge she can gain from watching the development of obesity could lead to clues about how to treat it.

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