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Obesity risk is visible in the brain

Robert Klatt

Disturbances in brain regions that control appetite and satiety show in advance an increased risk of obesity.


Turku (Finland). In recent years, scientists have discovered that the regulation of appetite in the brain is almost always impaired in people who are very overweight. In healthy people, insulin triggers a feeling of satiety in the brain, which regulates appetite. This function is reduced in obese people. In addition, receptors for reward messenger substances such as endogenous opioids and cannabinoids are only present in small numbers in people who are very overweight. In combination, this creates excessive caloric intake.


“Until now, however, it was unclear whether these changes in the brain are already visible before a person develops obesity and whether these changes increase the risk of future obesity,” explains Tatu Kantonen from the University of Turku in Finland.


Investigated changes in the brain

According to their publication in International Journal of Obesity The researchers examined the effects of the body’s own opioids and cannabinoids and insulin in the brain in 41 men between the ages of 20 and 35. About half (22) of the subjects were athletic and had parents who were neither suffering from type 2 diabetes nor overweight. The remaining test subjects (19) were already slightly overweight, had a lifestyle without much exercise and had parents who were either overweight or suffered from type 2 diabetes.

Examination by positron emission tomography (PET)

At the beginning of the study, the scientists used positron emission tomography (PET) to examine how glucose is distributed in the brain of the test subjects. This is an index of insulin activity. They also determined the number of receptors for opioids and cannabinoids. They found that “young men at high risk of future obesity had increased insulin-stimulated glucose uptake in the brain.” This was most evident in regions of the brain that control the feeling of hunger.

Reward system disrupted


“Disruptions in the action of insulin in the brain and impaired signal transmission between the brain and peripheral organs can contribute to a pathological dysregulation of the energy balance and to weight gain,” the scientists explain. This effect was already known from people with severe obesity. “Our results show that these pathophysiological processes are already active in non-obese people with risk factors for obesity,” the researchers say.

The study also shows that the risk of obesity also increases with a lower density of receptors for opioids and cannabinoids. “Previous studies have shown that downregulation of opioid receptors makes people more sensitive to rewarding food stimuli in the environment. People with a hereditary predisposition to downregulated opioid receptors could therefore react more sensitively to food stimuli in the environment, which leads to excessive food intake, ”the authors explain. Alternatively, it is also conceivable that people with fewer opioid receptors consume more food in order to trigger a response from the reward system.

New preventive measures against obesity

“Disturbances in the neural networks that control satiety and appetite can therefore be observed even before a person develops obesity, and these brain changes are linked to familial risk factors for obesity,” says Cantons. “The results could have implications for the development of obesity prevention and treatment interventions. They show that the brain and the central nervous system are important targets in the treatment of obesity, ”explains the scientist.

International Journal of Obesity, doi: 10.1038/s41366-021-00996-y



Reference-www.forschung-und-wissen.de

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