Inflammation can be thought of as the body’s response to a harmful stimulus; it can be a good thing when it protects the body, but it can become uncontrolled and self-perpetuating. Scientists have known for decades that obesity can cause a kind of low-grade inflammation that has been positively linked to such conditions as Type 2 diabetes and heart disease. In fact, some researchers categorize Type 2 diabetes as an inflammatory disease.
Until not long ago, research on the link between Type 2 diabetes and inflammation has concentrated on tissues like fat, muscle, the liver, and, especially, the pancreas, which is the organ that produces insulin. Recently, however, researchers at the Diabetes Center at the University of California-San Francisco studied the question of whether obesity-caused inflammation might affect the brain’s regulation of food intake.
In recent years, obesity has been proved to cause inflammation in the hypothalamus, the region of the brain that controls appetite and body weight. The Diabetes Center researchers, however, wanted to find out whether specific cells in the hypothalamus were involved in the inflammation process. They focused on cells called microglia (my-KROG-lee-ah), small cells that move throughout the central nervous system. In the brain, microglia play a role in instructing brain circuits to promote food intake, which initially drew the researchers’ interest.
The researchers discovered that saturated fats, when eaten in large amounts, accumulate in the hypothalamus; the microglia detect this build-up of fats and promote an inflammatory process that affects the food-regulating function of the hypothalamus. The researchers concluded that obesity causes inflammation in the hypothalamus, which changes the function of nerve cells that regulate how much we eat, which in turns stimulates food intake — a kind of vicious circle in which the excessive consumption of saturated fats causes overweight people to eat even more.
The scientists’ discovery of the relationship between food intake and the brain’s nerve cells was exciting, but they cautioned that it’s only a first step. Their goal now is to find a way to control the microglia. That path, they hope, will lead to finding new methods of controlling both obesity and Type 2 diabetes.