'Binge eating' linked to a specific group of neurons in the brain

In a remarkable discovery, researchers have pinpointed a specific group of neurons that appear to drive compulsive eating behaviors (binge eating), even in the absence of hunger.

This finding could significantly advance our understanding of eating disorders and offer new targets for treatment.

What is binge eating?

Binge eating, also known as compulsive eating, is a disorder characterized by frequent episodes of consuming large amounts of food, often rapidly and to the point of discomfort.

Unlike regular overeating, binge eating is driven by an overwhelming urge to eat, even when not hungry. People experiencing this disorder often feel a lack of control during these episodes and may eat in secret due to feelings of shame or guilt.

This behavior can lead to various physical health problems, such as obesity, diabetes, and heart disease. It also significantly impacts mental health, often associated with stress, anxiety, and depression.

The exact cause of binge eating is not fully understood, but it is believed to involve a combination of genetic, biological, and environmental factors.

Treatment typically involves therapy, such as cognitive-behavioral therapy (CBT), and sometimes medication to address underlying psychological issues. Early intervention is crucial for better management and recovery outcomes.

Neural link to binge eating

Located in the periaqueductal gray area of the midbrain – a region already associated with a variety of bodily functions such as mood regulation, sleep, and stress response – these neurons are identified as vesicular GABA transporter cells, or VGAT cells. They utilize the neurotransmitter GABA, which is pivotal in controlling neuronal activity.

Despite the known functions of VGAT cells in various brain regions, their relationship with feeding behaviors was previously unclear. This link was unveiled quite unexpectedly by researchers focusing on anxiety, not feeding.

“Our initial hypothesis centered on VGAT cells reducing fear and panic. Instead, activating them caused mice to frantically search for food,” noted Brazilian neuroscientist Fernando Reis, first and corresponding author of the article, and a postdoctoral fellow at UCLA. 

Surprising behaviors in lab mice

Further experimentation revealed intriguing results related to binge eating: well-fed mice exhibited an intense foraging behavior upon activation of these cells, consuming more than usual.

Conversely, when the VGAT neurons were inhibited, even food-deprived mice showed reduced eating behavior.

The experiments also demonstrated that the mice enjoyed the stimulation, spending more time where their VGAT cells were activated, suggesting that the activation not only spurred eating but also triggered feelings of pleasure and reward.

Remarkably, the mice were even willing to endure discomfort, such as mild electric shocks, to satisfy their induced cravings, indicating a strong drive to eat that overpowered other aversive sensations.

Advanced techniques and implications

The research employed the cutting-edge technique of optogenetics, which enables precise control over specific neurons using light.

This method was implemented by introducing a genetically modified virus that carries a light-sensitive protein derived from green algae into the mice.

As a result, only the targeted VGAT cells within the periaqueductal gray were selectively activated or inhibited.

This precise neural manipulation not only affected the periaqueductal gray but also influenced deeper brain structures, such as the zona incerta.

“We observed an increase in neural activity in this area when the mice were approaching food,” said Juliane Ikebara, a co-author of the study.

This observation underscores the broad impact of VGAT cell activation on the brain’s neural circuits involved in feeding behavior.

Understanding compulsive eating

The study raises intriguing questions about the potential parallels in humans, given that humans also possess VGAT cells in similar brain regions.

Although direct experimentation in humans is not currently feasible, the researchers are hopeful.

“Our findings can’t be directly tested in humans right now, but future studies may show whether activation of these cells in monkeys triggers a search for food, suggesting something similar might happen in humans,” noted Avishek Adhikari, the team’s senior researcher.

Moving forward, the team plans to investigate whether stimulating these neurons influences cravings for specific types of food like proteins or sugars, noting a distinct preference in mice for high-calorie foods over vegetables.

Treating compulsive eating disorders

This discovery opens up potential new avenues for understanding and treating conditions such as binge eating and anorexia.

By identifying the neural circuits involved in compulsive eating, researchers can explore innovative strategies to modulate these behaviors, offering hope for those battling eating disorders.

The research not only highlights the complex interplay between brain regions and binge eating behaviors but also underscores the potential for targeted neural interventions in addressing compulsive eating.

The study is published in the journal Nature Communications.

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