Sweets reshape the brain and lead to overeating

we know that high-fat, high-sugar foods can change waistlines, but little is known about how they change the brain. Now, researchers have found that swapling a mouse's diet from standard to fatter foods can alter the activity of certain neurons that control the diet and cause cells that limit energy intake to "brake". If the same is true in humans, the findings may help explain the tendency to overeating.
Garrest Stuber, a neurobiologist at the University of North Carolina at Chapel Hill, has been trying to understand the brain changes that accompany obesity. They are particularly interested in the area at the bottom of the brain that controls eating - the outer lower pasum.
, who now works at the University of Washington in Seattle, and their British collaborators sequenced cells in this area of the mouse brain and grouped them according to the genes they expressed. Using gene expression from obese mice on a higher-fat diet and control group mice on a standard diet, the researchers found that some neurons changed significantly after eating foods that led to obesity.
region expresses the genes of the excitable signaling molecule glutamate. The researchers looked at glutamate energy cells in the brains of living mice using a double photon microscope. They gave the cells a gene that makes them fluorescent when they absorb calcium, an indicator of nerve activation. Then, when the mice licked the calorie-rich sugary water, they looked at the cells.
showed that if a thin mouse had just eaten, neurons responded more to sugar than they did on an empty stomach. These cells seem to act as "brakes" and signal: "Enough is enough!" "But when thin mice became obese because of their high-fat and high-sugar diets, these cells became less active. The team recently reported in Science that glutamate cells responded to sugary drinks by about 80 percent in the 12 weeks after the change in diet.
, a neuroscientist at the University of Aberdeen, said the study was the first to look at animal brain activity for a long time using calcium imaging, which is a "smart way" to study how obesity develops. One explanation for the study, she says, is that eating sweets and high-fat foods "changes the brain's appetite center function, which means we eat more than we need because the brain reacts less to sweets."
the study did not distinguish between what altered neural activity: whether it was a characteristic of diet or weight gain itself. Experts point out that it also does not prove that changes in brain activity itself lead to overealing and weight gain in animals
(Source: Tang
, China Science Journal)