Abnormal activity of brain circuit may be associated with anorexia, study finds

According to a new study, abnormal activity in a particular brain circuit was found to be an underlying cause of anorexia in an animal model.

The study, published in Nature Neuroscience, was conducted by a team of researchers at Baylor College of Medicine, Louisiana State University, and collaborating institutions. The investigation was an expansion of a previous study which found that dysfunction of dopamine and serotonin neurons were associated with anorexia, an eating disorder that often causes individuals to severely restrict calories and exercise excessively, according to the researchers. The study analyzed how the interaction between dopamine neurons and serotonin neurons regulate food consumption in an animal model.

Researchers found that dopamine neurons and serotonin neurons communicate regardless of an animal’s eating pattern, however, the strength of the signal along the dopamine-serotonin brain circuit was a significant indicator of how much the animal would eat.

“When dopamine neurons fired a lower-frequency signal, for example, between two and 10 Hertz, the result was inhibition of the serotonin neurons and overeating behavior,” said Yong Xu, MD, PhD, professor of pediatrics-nutrition and molecular and cellular biology at Baylor College. “On the other hand, when dopamine neurons fired at a higher frequency between 10 and 30 Hertz, the serotonin neurons were activated, and this led to lack of feeding.”

The team also found that the dopamine receptor DRD1 caused some of the hyperactivity in the identified brain circuit. When the researchers removed the DRD1 gene from the animal models, the animals’ eating, and exercise behaviors became more normal.

“The findings suggested that pharmacologically inhibiting the DRD1 receptor could also help reduce the circuit’s hyperactivity, an approach that could have clinical applications,” said Xu. “Indeed, we found that a drug that interferes with DRD1 receptor activity can effectively prevent anorexia and weight loss in the animal model. These findings support further studies toward developing a similar therapeutic approach for individuals with anorexia.”