In a new study, researchers from the United States, Sweden, and the United Kingdom found that certain brain cells involved in suppressing overeating became less active after feeding a high-fat diet to mice. The results of the study were published in the journal Science on June 28, 2019, entitled “Obesity remodels activity and transcriptional state of a lateral hypothalamic brake on feeding.” In this paper, they describe experiments conducted with over-fed experimental mice and what they have learned. Stephanie Borgland of the University of Calgary, Canada, published an article in the same period of the journal Science entitled “Releasing the brake on eating”.
Most obese people know that the more they eat on high-fat foods, the harder it is to stop. In this new study, these researchers may have discovered some of the reasons. In their experiments, they cut holes in the skulls of the experimental mice and blocked them with tiny windows to observe neurons in the brain using a special microscope. They then fed these mice a high-fat diet and observed that they slowly became obese.
Given that previous studies have shown that lateral hypothalamus, part of the brain, is involved in regulating hunger, these researchers are particularly concerned with brain activity in the lateral hypothalamus. More specifically, glutamatergic nerve cells in the lateral hypothalamus are involved in suppressing hunger. Their job is to tell the mice to eat enough food. In experiments in which these cells encountered dysfunction, these mice became gluttons. But so far, it is unclear how these cells behave in their “on” state in the case of mice becoming gluttons.
These researchers reported that glutamatergic neurons in these mice became less active during the self-release period and when given a syrup, only after two weeks of the high-fat diet regimen. They further reported that as these mice ingested high-fat fats over a 12-week period, the reduction in cellular activity continued. Borgland explained that a high-fat diet eliminates the natural inhibition of binge eating, which leads to obesity.
It is unclear whether the same type of cells in humans work in the same way, but these researchers point out that previous studies have shown that the human hypothalamus is involved in regulating hunger.