Study shows how the will to eat dominates the brain signal

Researchers at the University of Michigan have studied two groups of brain cells competing for control of eating behavior and found that cells that grow to eat miss those that signal stopping.

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The study also showed that the opioid system of the brain is involved and that the administration of a drug called naloxone can block this system.

They say that their findings could contribute to the fight against the global epidemic of obesity.

In a mouse model, Huda Akil and colleagues studied two groups of brain cells called pro-opiomelanocortin (POMC) and AgRP (Agouti-associated peptide-gene). The two groups are located close to each other in a region of the brain called the arcuate nucleus, which is part of the hypothalamus regulating behavior.

Previous studies have shown that the POMC responds to certain signals in the body by limiting the urge to eat, while the AgRP stimulates the urge to eat, especially when food is scarce or infrequent. when the last meal has passed.

As indicated in Proceedings of the National Academy of Sciences, The current study has shown how the two groups of cells are related to each other. Using a technique called optogenetics, Akil and his team stimulated POMC, since POMC neurons had already shown their role in eating behavior.

However, the result of POMC cell stimulation was that a group of neighboring AgRP cells was also stimulated. These two groups of cells are derived from the same parental cells during embryonic development, which means that the technique used by the researchers to target the POMS also captured the AgRP nerve cells.

Interestingly, the team found that when both groups of cells were activated, AgRP's "continue to eat" signal had the most influence on eating behavior. This AgRP signal was more powerful than the "stop eat" signal generated by POMC.

"When both are stimulated at the same time, AgRP steals the show," says Akil.

The researchers then used a technique called c-fos activation to further study the downstream effects of POMC and AgRP activation.

They found that the activation of the AGRP also activated the opioid system of the brain and that the administration of naloxone, an opioid antagonist, prevented eating.

"This suggests that the endogenous opioid system of the brain may play a role in the desire to eat beyond what is necessary," said Akil.

The discovery led Akil and his team to wonder if the bombardment of the senses with what we see, smell and interact socially with food may be implicated in the need to overeat.

She may think that these factors encourage us to be interested in eating when we are not even hungry: "An entire industry is about encouraging you to eat, whether you need it or not: People are just hungry by looking at them, and we need to study the neural signals involved in these attentional mechanisms of perception that drive us to eat. "