"The PACAP system may hypothetically be the target of medications to treat not only obesity but also binge-eating, a disease characterized by excessive, uncontrollable consumption of food within brief periods of time," says Pietro Cottone. (Credit: iStockphoto)

brains

Adding peptide to brain could shrink meals

Scientists have discovered that administering a peptide and hormone to a specific area of the brain may reduce the desire for food.

The study, which appears in the journal Neuropsychopharmacology, could one day lead to medications that treat obesity and binge eating disorders.

Working with rats, the researchers found that administering pituitary adenylate cyclase-activating peptide (PACAP), a peptide and hormone produced by neurons, in a specific area of the brain called the “central amygdala,” reduced eating and led to weight loss.

According to the researchers PACAP is known for its food intake and body weight effects in the hypothalamus (the area of the brain known for controlling appetite).

However, this is the first report of PACAP effects in the amygdala, a region of the brain outside the hypothalamus, involved in fear as well as the emotional component of eating.

Smaller meals, less food

The researchers also discovered how PACAP decreases food intake when injected in the amygdala.

In general, food intake can be decreased in two ways: eating fewer meals of normal size during the day, or smaller meals.

“We found that amygdalar PACAP reduces the amount of food eaten within meals, but not how many meals are consumed. In addition, we found that PACAP reduced the rate of intake of food. This means that, following administration of PACAP, models were eating more slowly,” explains Valentina Sabino, assistant professor of pharmacology and psychiatry, and co-director of the Laboratory of Addictive Disorder at Boston University School of Medicine (BUSM).

In addition, they found that PACAP effects on food intake and body weight were dependent on another brain factor: the growth-hormone called brain-derived neurotrophic factor (BDNF).

“The effects of PACAP on food intake and body weight were absent when it was given together with another drug that blocks BDNF signaling, suggesting that PACAP acts through BDNF,” says Sabino.

Obesity and binge-eating

The researchers believe these findings have implications for a variety of conditions, since they found not only how much food subjects ate, but also how fast they ate it.

“The PACAP system may hypothetically be the target of medications to treat not only obesity but also binge-eating, a disease characterized by excessive, uncontrollable consumption of food within brief periods of time,” adds coauthor Pietro Cottone, associate professor of pharmacology and psychiatry and co-director of the Laboratory of Addictive Disorder at BUSM.

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Obesity is a complex disorder, affecting more than 78 million Americans, that involves an excessive amount of body fat. It increases the risk of diseases and health problems such as heart disease, diabetes, and high blood pressure.

Binge-eating disorder involves periods of excessive uncontrolled consumption of food, followed by uncomfortable fullness and feelings of self-disgust.

Funding for this study came from the National Institute of Health (National Institute of Mental Health and National Institute on Drug Abuse), the Peter Paul Career Development Professorship, the Peter McManus Charitable Trust, and Boston University’s Undergraduate Research Opportunities Program (UROP).

Source: Boston University

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