​Hunger games: Scientists manipulate gluttony & food cravings in mice

Reuters/Aly Song  CC/KS
Researchers have identified the brain cells that control feelings of hunger and learned to manipulate them in mice, raising hopes for dieters and people with obesity problems that a drug may eventually be found to switch off the urge to eat.

The experiments by British and American researchers were done on genetically engineered mice, but scientist believe they can eventually apply their study to the treatment of humans.

The research focused around a tiny group of cells called the PVH MC4R neurons (melanoncortin 4 receptor-regulated neurons in the paraventricular nucleus of the hypothalamus). Although they count for just a few hundred neural links between the billions of brain cells in our brains, they are crucial in controlling hunger. Switching them off heightens the feeling of hunger while switching them on kills it.

The scientists switched off the cells on mice who, even though they had just eaten, became ravenous.

Whereas switching on the ‘hunger hub’ cut the mice’s appetite even though they had barely eaten.

A second experiment then tried to see what feelings the mice experienced when the PVH MC4R ‘hunger’ produced when switched on.

Hungry mice were put in a clear box in two rooms, one of which was beamed with a laser light which activated the cells. These mice were drawn into this side of the box suggesting they liked whatever was happening to their brains.

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But animals who had just eaten divided their time equally between the two rooms. The cells did not apparently stop their appetite by creating unpleasant sensations like nausea, but rather, through calming feelings of irritation and hunger pangs, just like humans feel better and more relaxed after a meal.

“Our results show that the artificial activation of this particular brain circuit is pleasurable and can reduce feeding in mice, essentially resulting in the same outcome as dieting but without the chronic feeling of hunger,” the coauthor of the study, Bradford Lowell of Harvard’s Beth Israel Deaconess Medical Center, said in a statement.

Dr Alastair Garfield from Edinburgh University said that the researchers managed to get round the usual gnawing sensation of hunger.

“If you could design a magic bullet, something that could fly through the brain and hit just these cells and turn them on, then I think we would see the same effects in humans and mice,” he told the Daily Mail.

But scientists also cautioned that any drug that tinkers with brain chemistry would have to be thoroughly tested before it was cleared for use - something that is many years away.

Others warned that drugs and medicines won’t help obese people who comfort-eat and argued that the only way to solve an eating disorder is to change behavior and break bad habits.