Scientists Discover the Brain Circuit that Controls Compulsive Overeating and Sugar Addiction

Compulsive overeating and sugar addiction are both major problems for human health. Now, though, scientists may have identified the neural circuit that specifically controls sugar consumption in mice. The findings could eventually lead to a safe and effective treatment for compulsive overeating in humans.

"Although obesity and Type 2 diabetes are major problems in our society, many treatments do not tackle the primary cause: unhealthy eating habits," said Kay Tye, the senior study author, in a news release. "Our findings are exciting because they raise the possibility that we could develop a treatment that selectively curbs compulsive overeating without altering healthy eating behavior."

Compulsive overeating is a type of reward-seeking behavior. In that respect, it's similar to drug addiction. Yet the major difference between the two behaviors is that eating is required for survival, which underscores the need to tease apart brain circuits involved in compulsive overeating versus normal eating in order to develop therapies.

The researchers suspected that a neural pathway from the lateral hypothalamus to the ventral tegmental area might play an important role in compulsive overeating. In over to investigate a bit further, the researchers used a method called optogenetic, which involves genetically modifying specific populations of neurons to express light-sensitive proteins that control neuroexcitability. Then, they deliver either blue or yellow light through an optic fiber to activate or inhibit these cells, respectively.

So what did they find? When the scientists activated this pathway in mice, they spent more time feeding and increased the number of times that they poked their noses into a port to receive a sugar reward, even when they had to cross a platform that delivered foot shocks to get the reward. In contrast, inhibiting this pathway reduced the compulsive sugar-seeking behavior without decreasing food consumption in hungry mice.

"We have not yet adapted to a world where there is an overabundance of sugar, so these circuits that drive us to stuff ourselves with sweets are now serving to create a new health problem," said Tye. "The discovery of a specific neural circuit underlying compulsive sugar consumption could pave the way for the development of targeted drug therapies to effectively treat this widespread problem."

The findings are published in two articles in the journal Cell here and here.

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