American researchers have been able to understand how the brain mechanism, which contributes to eating only for pleasure, works.
When you eat something super tasty, you wonder why you do not want to stop, even though you know you've eaten enough? Scientists at the University of North Carolina Medical School (UNC) in Chapel Hill, North Carolina, USA, may have found the cause: a brain chain.
In laboratory experiments, Thomas Kash, an eminent professor in the department of pharmacology, and his colleagues discovered a specific cellular communication network that originated in the brain area that handled emotions, motivating mice to continue eating delicious foods, even though the main energy needs.
"This scheme 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.
Scientists seeking anti-obesity have spent decades exploring and coping with brain cells and circuits involved in the usual "homeostatic" diet that is triggered by hunger and keeps our high energy levels. But 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 believed that the hedonic diet reflects the long-term adaptation of modern humans to ancient environments where hunger was honor. Perceiving foods rich in calories as particularly tasty and enjoyable and consuming them whenever they are available would provide a key survival advantage by adding extra 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 calorie-rich foods that are available all the time now, and we have not yet lost this plant, which affects us to eat as much food as possible," Kash adds. Experiments over recent years have shown that our wiring for hedonic feeding includes 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 slow down hedonic overeating. in delicious and high-calorie foods. Therefore, pharmaceutical developers view these antagonists as possible anti-obesity and anti-thicker drugs and researchers are ready to identify the specific brain circles through which they work. The goal is to develop a more specific treatment.
The identification of this chain has largely been achieved by Kash and his colleagues in his new study. They 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 have noticed that one has been activated when mice have the ability 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 research is one of the first to describe how the emotional center of the brain contributes to eating for pleasure. He adds support to the idea that everything that 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 amygdala. 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. "The behavioral effects of blocking nociceptin activity probably involve multiple mechanisms in the brain," says Kash, "but in general, nociceptin blockade appears to stabilize behavior by bringing it to normal."