The discovery of the brain’s so-called melanocortin system and its central role in controlling appetite has paved the way for entirely new possibilities for treating obesity and anorexia. In the latest issue of the prestigious journal Nature Reviews Drug Discovery, Uppsala University researcher Jarl Wikberg and one of his associates present a review of pioneering research in this field that he and other scientists have conducted over nearly two decades.
The mapping of the melanocortin system was made possible by the cloning of genes for five different melanocortin receptors, which was performed by Jarl Wikberg in collaboration with other researchers in the early 1990s.
“The melanocortin system monitors the energy balance and regulates how much we eat and how much energy the body uses. The result of all of this is that we maintain our body weight,” says Jarl Wikberg.
But things can go wrong. It is a highly complex system, and even tiny imbalances can entail major changes. For instance, the melanocortin system is exposed to great genetic variations, and many mutations lead to extreme obesity in early ages. Such mutations are found in 3–6 percent of children who have these problems.
“There are also mutations that affect the system in the opposite direction, and these may be an explanation for anorexia.”
These discoveries have prompted most major drug companies to develop drugs that target melanocortin receptors, for the treatment of eating disorders. Interestingly, the same system has also been shown to be involved in the regulation of sexual behavior, and this has resulted in the creation of drugs for treating diminished sex drive as well.
“In men such treatment has become accepted, but it is still controversial to treat women. It will be interesting to see how an effective treatment for diminished sex drive will be received in the future,” says Jarl Wikberg.
Source: Uppsala University
Related stories:
Common mutations linked to common obesity in Europeans
Scientists have discovered two common genetic mutations in people of European ancestry, which affect the production of several hormones controlling our appetite. The mutations have a significant effect on the risk of common obesity, according to research published today in
Nature Genetics.
Low dose of serotonin-acting chemical improves blood sugar tolerance
An appetite-suppressing chemical also improves glucose tolerance and lowers insulin levels in obese and diabetic mice, researchers report in the November issue of
Cell Metabolism, a publication of Cell Press. Importantly, the researchers found, those effects of the drug occurred at a low dose that had no influence on feeding behavior, body weight, activity level, or energy expenditure.
Discovery of gene for black coat color in dogs has broad implications
The discovery of a gene responsible for black coat color in dogs may help researchers understand fundamental processes in humans, including the regulation of body weight and stress hormones.
Researchers sniff out gene that gives dogs black fur
A discovery about the genetics of coat color in dogs could help explain why humans come in different weights and vary in our abilities to cope with stress, a team led by researchers from the Stanford University School of Medicine reports.
Brain system serves as 'remote control' for fat metabolism
A system in the brain already known to regulate food intake also serves as a direct “remote control” for the way fat is stored and metabolized in the body, say University of Cincinnati (UC) researchers.
Interaction of just 2 genes governs coloration patterns in mice
Biologists at Harvard University and the University of California, San Diego, have found that a simple interaction between just two genes determines the patterns of fur coloration that camouflage mice against their background, protecting them from many predators. The work, published this week in the journal
PLoS Biology, marks one of the few instances in which specific genetic changes have been linked to an organism's ability to survive in the wild.
Fat fish put obesity on the hook
Everyone knows that eating lean fish helps slim waistlines, but researchers from the Center for the Study of Weight Regulation and Associated Disorders at Oregon Health and Science University in Portland, OR, have found a new way fish can help eliminate obesity. In a study to be published in the July 2007 print issue of The FASEB Journal, researchers describe the first genetic model of obesity in a fish. Having this model should greatly accelerate the development of new drugs to help people lose weight and keep it off.
Study pinpoints how genetic glitch could keep some people from feeling full
Nearly 6 percent of morbidly obese children and adults have a genetic defect that keeps them feeling like their stomach is running on empty, no matter how much they have eaten.