The protagonists of our history are called microglia, and although they are not neurons, they account for 10 to 15% of the brain cells. They form the immune system of the central nervous system and, according to a mouse study by researchers at the University of Washington Medical Center and the University of California, San Francisco, are key to weight gain.
What is interesting about this research is that it could turn microglia into the key to developing new treatments and drugs against obesity, one of the main threats to health in developed countries.
The microglia of the hypothalamus fatten you
In a region of the brain called the mediobasal hypothalamus, there is a group of neurons in charge of balancing food intake and the body’s energy expenditure. They generally manage to maintain a balance between calories consumed and burned, but previous research has shown that a diet rich in fat breaks this balance and triggers the mechanisms that lead us to accumulate fat. Eating high-calorie foods is already fattening, and also makes us more likely to gain extra pounds, even if we don’t binge.
In this new study, the researchers put a group of mice on a high- fat diet for four weeks, something that, as was already known, increases the number of microglia and inflames the midbasal hypothalamus. These rodents not only had more appetites than those with a healthy diet; they also burned fewer calories and gained more weight.
To find out if microglia were responsible for the mice’s overeating and obesity, the researchers used an experimental drug that reduces the number of microglia in the hypothalamus. They found that the animals treated with this substance ate 15% less and gained 20% less weight than those that did not receive it, although the two groups followed the same diet.
Genetically modified mice
In addition, the University of Washington team genetically engineered other mice so that their microglia did not activate inflammatory responses in the hypothalamus. The modified rodents ate 15% less and gained 40% less weight than their counterparts, although both groups received the same high-fat foods.
These results suggest that the inflammatory action of the microglia has a fundamental influence on the excessive intake and the corresponding fattening of the animals studied. According to the researchers, “these experiments indicate that inflammatory activation of microglia is not only necessary for a high-fat diet to cause obesity, but is sufficient by itself to alter the regulation of the energy balance of the hypothalamus, leading to to get fat ”.
Now, the goal is to carry out clinical trials in humans to confirm this process, and to develop drugs that act on microglia and prevent them from inflaming the brain, which would help fight obesity.