Addiction changes the brain

Rats show typical brain and behavioral changes

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That sugar is addictive, you hear again and again. Now, however, researchers have gathered in experiments on rats further evidence that it is the addiction really is a classic addiction with all that goes with it: cravings, withdrawal symptoms and many relapses.

Professor Bart Hoebel and his team of neuroscientists at Princeton University have been on the trail of "sugar addiction" for years. They have already revealed that rates in the attempt have at least two out of three characteristics of an addiction, once they get used to sweets: they eat more of them over time and they show withdrawal symptoms. Their latest experiment was to find out whether rats also have the third feature of addiction, the heightened sweetness, and the recidivism.

Missed "breakfast" triggers eating attack

"If extreme snacking is really a form of addiction, then there should be long-lasting effects in the brains of sugar addicts, " explains Hoebel. "Food cravings and relapses are crucial components of an addiction." In the experiment, the scientists initially used laboratory rats for sugar water, but deprived them of it during sleep and four hours after waking.

It was found that the experimental animals tried to compensate for the loss by taking a particularly large amount after the withdrawal phase. "It's a bit like missing the breakfast, " explains Hoebel. "As a result, they quickly eat something and drink a lot of sugar water. This is what is also called a binge eating - when you eat a lot at once. In this case, it was a ten percent sugar solution, which is equivalent to a soft drink. "

Alcohol as a replacement drug

After the withdrawal phase, the motivation to search for sugar water or to develop it seemed to have increased. In further experiments, rats on withdrawal withdrew more than control rats to receive sugar water as a reward for a task. "In this case, absence awakens the desire, " says Hoebel. display

When the researchers provided the rats with alcohol as a substitute for alcohol diluted with water, they drank considerably more than normal, non-sugar-addicted animals. According to Hoebel, this indicates that the brain must have had addictive changes that pave the way for other addictions.

Covetousness causes remodeling in the brain

In fact, Hoebel and his team also discovered a specific change in their brain metabolism in their rats: when the hungry animals drank sugar water, the messenger substance dopamine was released in the region of the nucleus Accumbens. It is considered a chemical signal that triggers motivation and repetition over time, addiction. This was shown in the rat brains after about a month sugar water abundance in the form of adjustments to the constant dopamine influx. There were fewer dopamine receptors in the brain and more opioid docking sites. Similar changes had previously been observed in rats who were addicted to cocaine or heroin.

Withdrawal symptoms after dopamine waste

According to the researchers, the signs of withdrawal symptoms observed in the experiments are also related to the metabolism of dopamine in the brain: if the rats were deprived of the sugar water, the concentrations of dopamine in the brain dropped sharply, and as a result the behavior of the Animals: Their teeth chattered and they refused to enter the open arm of a labyrinth. Rats usually like to explore their surroundings, but the "withdrawal" rats were suddenly too anxious to venture out.

Similar changes in humans?

But what do these experiments on rats tell us about the effect of sugar in humans? Can the results be transferred so easily? According to Hoebel, more research has yet to be done before the meaning for man becomes clear. Nevertheless, he can imagine a similar mechanism, for example, in people with eating disorders:

"It seems likely that the changes in brain and behavior seen in our rats also occur in some people with binge eating or bulimia, " Hoebel says. Our work links the traditionally defined drug rights with the development of abnormal cravings for natural substances. This knowledge could help us to find new ways to diagnose and treat such breeds in humans. "

(Princeton University, Jan 2, 2009 - NPO)