Neurons of gluttons

Neurons responsible for cravings for fatty foods and overeating have been identified in the hypothalamus

Maria Azarova, Naked Science

Since the 1980s, all over the world, especially in developed countries, there has been an increase in the number of people suffering from obesity and related problems - in particular, diabetes mellitus and diseases of the cardiovascular system. And although in recent years the trend for a healthy lifestyle, veganism and proper nutrition has been actively developing and promoted, many of us remain inclined to eat something harmful, fatty, but so beloved and delicious in the evening.

As scientists from the Max Planck Institute for Metabolism Research in Cologne found out, this love of high–calorie and fat–saturated food, as well as craving for overeating, is regulated by a group of nerve cells in the brain: to be more precise, nociceptive neurons in the hypothalamus (part of the limbic system - the subcortical zone where the centers of emotional reactions and reproductive behavior are located).

As reported in a paper published in the journal Neuron (Jais et al., PNOC ^ARC Neurons Promote Hyperphagia and Obesity upon High-Fat-Diet Feeding), biologists conducted an experiment on mice to establish which nerve cells control overeating and a tendency to high-calorie food. To do this, genetically modified rodents, in which the activity of nociceptin neurons in the hypothalamus could be monitored using a glowing molecule, were put on a high-fat diet.

Nociceptive neurons in the arcuate nucleus of the mouse hypothalamus / © The Max Planck Society.

"Just a three–day diet based on high–calorie fatty foods was enough to detect increased activity of nociceptin neurons (a neuropeptide consisting of 17 amino acids – ed.) in a certain area of the brain - the arched nucleus of the hypothalamus," says lead author of the study Alexander Jais.

To confirm their results, scientists selectively removed these neurons from some of the experimental mice: after that, the animals stopped showing excessive love for fatty foods and lost their tendency to overeat, and this did not affect the consumption of healthy food in any way. Thus, the authors conclude, it is the activation of nociceptive neurons that can specifically control the love of high-calorie fatty foods and "gluttony".

"We are constantly surrounded by cheap, delicious and high–calorie foods, and our brain is designed so that we prefer this kind of food," explains Jice. "It is still unknown why some people manage to eat only as much as they need, while others do not. The individual activity of nociceptive neurons can be an important part of this puzzle. Their activities contribute to excessive consumption [of high–calorie fatty foods] - and this makes them an attractive target for the prevention and treatment of obesity."

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