Overeating makes the brain go haywire, prompting a cascade of damage that may cause diabetes, heart disease and other ills, U.S. researchers recently reported. Eating too much appears to activate a usually dormant immune system pathway in the brain, sending out immune cells to attack and destroy invaders that are not there, research found.
The finding, reported in the journal cell, could help explain why obesity causes so many different diseases.
It might also offer a way to prevent obesity itself. Obesity is a growing global problem, with 1.8 billion people estimated to be overweight or obese in 2007. Drugs marketed so far to fight obesity have only limited success and, often, severe side-effects. Obesity causes chronic inflammation throughout the body. This inflammation is found in a range of diseases related to obesity, including heart disease and diabetes.
Immune cells such as macrophages and leukocytes use it but research team found it in the hypothalamus, a part of the brain linked with metabolism in mice and humans alike.
"The hypothalamus is the 'headquarters' for regulating energy," they wrote. They found high levels of the compound there but it was normally inactive.
When they fed mice a high-fat diet, it became extremely active. And when it was active, the body ignored signals from leptin, a hormone that normally helps regulate appetite, and insulin, which helps convert food into energy.
The team has discovered a master switch for the diseases caused by overeating.
Team does not know why this compound would be in the brain and in the immune system but suspects it evolved long ago in primitive animals that do not have the same sophisticated immune system as modern animals, including mice and humans.
"Presumably it played some role to guide the immune defense," they said. "In today's society, this pathway is mobilised by different environmental challenge over-nutrition."
'Knocking out' the gene using genetic engineering kept mice eating normally and prevented obesity. This cannot be done in people but team believes a drug, or even gene therapy might work.With gene therapy, a virus or other so-called vector is used to carry corrective DNA into the body, but the approach is still highly experimental.
