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Scientists find out why sometimes we can not stop eating – April 25, 2019

When you eat something delicious, did you ask why do not you want to stop, even though you know you've eaten enough? Scientists at the University of North Carolina Medical School (UNC) in Chapell Hill, North Carolina, USA may have found the reason: brain chain,

In laboratory experiments, Thomas Kash, a prominent professor in the department of pharmacology, and his colleagues found a specific network of cellular communication that originated from the area of ​​the brain that processes the emotions, motivating mice to continue eating delicious foods even though their basic energy needs have been met.

The existence of this mammalian brain chain described in an article in the journal Neuron may help to explain why people often eat more in our modern environment of abundant and delicious food. The chain is a by-product of evolution, when high-calorie foods were scarce, so our brains were designed to absorb as many calories as humanly possible because no one knew when the next super food would come,

"This circuit seems to be the way the brain tells you that if something is really good then it is worth the price you pay to get it, so do not stop"explains Kas.

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Scientists seeking anti-obesity have spent decades exploring and dealing with brain cells and circuits involved in the usual "homeostatic" nutrition, which is triggered by hunger and keeps our energy level highBut this approach had limited success. More recently, some researchers studied hedonic food, eating high-calorie foods with pleasure, which usually exceed our strict energy needs.

It is considered that hedonic nutrition reflects the long-term adaptation of modern humans in ancient environments, where hunger was honor. Perceiving foods rich in calories as particularly tasty and enjoyable and consuming them when available will be provided a decisive survival advantage by accumulating additional energy. Following this instinct now, at a time of abundance, can lead to obesity, a condition that affects approximately 40% of US adults only and related diseases such as diabetes, heart disease and cancer.

– There are so many foods rich in calories at present, and we have not lost this installation, which still affects us Experiments in recent years have shown that our hedonic feeding wires include nociceptin, a small protein that functions as a signal molecule in the mammalian nervous system.

The Kash Laboratory and other groups have found that compounds that block nociceptin activity, called nociceptin receptor antagonists, have little or no effect on the homeostatic diet of rats and laboratory mice, but these compounds stop hedonistic overeating in delicious and high-calorie foods. Therefore, pharmaceutical entrepreneurs consider these antagonists to be possible anti-obesity and anti-overeating medicinesand researchers are ready to identify the specific brain circles through which they function. The goal is to develop a more specific treatment.

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The identification of this chain has largely been achieved by Kash and his colleagues in his new studyThey have designed mice to produce a fluorescent molecule along with nociceptin, literally illuminating the cells that lead to the nociceptin circles. There are a number of nociceptin circuits in the brain, but Kash and his colleagues watched him one in particular was activated when mice are able to consume high calorie foods.

The chain is designed in different parts of the brain, including those known to regulate nutrition. It starts in an area of ​​the brain that processes the emotions called the central amygdala. Elimination of approximately half of nociceptin-producing neurons in this chain reduces mice bloating and retains weight when they have access to rich foods without affecting the consumption of plain food.

"Scientists have been studying amygdala for a long time, and it has been associated with pain, anxiety and fear, but our findings here emphasize that he also does other things, such as regulating pathological nutrition," says Kash. Now he and his team have been studying in more detail how this scheme works, the timing of its activity on food and other factors, and how nociceptin antagonists alter their functions.

The first author of the work, J. Andrew Hardaway, assistant professor of pharmacology at the UNC School of Medicine, says: "Our study is one of the first to describe how the emotional center of the brain contributes to eating for pleasureHe adds support to the idea that everything mammals eat is dynamically classifiable from a range of good / tasty to bad / disgusting, and this can be physically presented in subgroups of neurons in the amygdala. The next important step and the challenge is to take advantage of these subgroups to get new therapies for obesity and overeating.

Other scientists are studying nociceptin antagonists as a possible treatment not only for obesity and overeating but also for depression, pain and substance misuse. Behavioral blocking effects of nociceptin may include multiple mechanisms in the brain, "says Kash. But overall blockade of nociceptin seems to stabilize the behavior that brings it closer to normal. "

Source: DPA / Europa Press

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