'Brain circuit involved in impulsive feeding behaviour found'

Researchers have identified a specific circuit of nerves in the brain involved in impulsive feeding behaviour, an advance that may lead to drugs for addressing overeating.

The researchers, including those from the University of Georgia (UGA) in the US, said impulsiveness -- or responding without thinking about the consequences of an action -- is linked to excessive food intake, binge eating, weight gain, and obesity, along with several psychiatric disorders such as drug addiction, and excessive gambling.

In mice brains, they assessed a subset of cells that produced a chemical messenger molecule called melanin concentrating hormone (MCH).

The researchers said the hormone is produced in a brain area called hypothalamus -- a small region at the base of the brain that plays a crucial role in many important functions, such as releasing hormones, and regulating body temperature.

In the current study, published in the journal Nature Communications, the researchers activated cells in the hypothalamus which produced MCH. 

They found that the animals became more impulsive in their behaviour around food. 

To test the effects of the brain stimulation, the scientists trained rats to press a lever to receive a "delicious, high-fat, high-sugar" pellet.

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But the rat had to wait 20 seconds between lever presses, the study noted. 

If the rat pressed the lever too soon, it had to wait an additional 20 seconds.

The researchers also activated a specific pathway in the brain's nerve connections from the hypothalamus to a region called the hippocampus -- involved with learning and memory function. 

They found that the MCH doesn't affect how much the animals liked the food, or how hard they were willing to work for it. 

Instead, they said the circuit acted on the animals' inhibitory control, or their ability to stop themselves from trying to get the food.

"Activating this specific pathway of MCH neurons increased impulsive behaviour without affecting normal eating for caloric need or motivation to consume delicious food," said Emily Noble, study co-author from UGA. 

According to the researchers, understanding this circuit -- which selectively affects food impulsiveness -- can help develop therapeutics for overeating. 

They said such treatment can help people stick to a diet without reducing normal appetite, or in making delicious foods less delicious.