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'Gluttony gene' stops mice feeling full

26 March 2012
Appeared in BioNews 650

A mutation in a gene linked to obesity causes mice to eat up to 80 percent more than normal, a study suggests.

After eating, hormones send signals to the brain to let it know it's full. However, scientists found that in mice with a faulty version of the BDNF gene, these messages were 'blocked'.

'If there is a problem with the BDNF gene, neurons can't talk to each other, and the leptin and insulin [hormone] signals are ineffective, and appetite is not modified', said researcher Professor Baoji Xu from the Georgetown Medical Centre in the USA.

When the team monitored the eating habits of mice with and without the mutation, they found males were twice as heavy as their normal counterparts, and females were 2.7 times heavier. This was to do with them over-eating, rather than a reduction in their activity levels.

An additional part of the study, published in Nature Medicine, looked at what happened when leptin, often referred to as the 'hunger hormone' due to its role in regulating appetite, was injected into the mice. While the hormone had no effect on the mice with the BDNF mutation, there was a 26 percent reduction in amount of food eaten in those with a non-mutated gene.

The researchers now hope to use these results to help control obesity in humans.

Professor Xu said: 'This discovery may open up novel strategies to help the brain control body weight'.

However, any future treatment is still a long way off. Although we do have the BDNF gene, the mutation examined in this study is rare in humans and it cannot be assumed that human bodies react in exactly the same way as mice.

Tam Fry, spokesman for the National Obesity Forum, told the Daily Mail that 'fixing the mutation may not be plain sailing' and 'even when its fixed in mice it will be years before his solution can he be used in humans'.

Dendritically targeted Bdnf mRNA is essential for energy balance and response to leptin
Nature Medicine |  18 March 2012
Eating too much? It's all in the genes |  19 March 2012
'Gluttony gene’ may be behind big appetites
Independent (PA) |  19 March 2012
‘Greedy gene’ that makes you eat more even when you are full is uncovered by scientists
Daily Mail |  18 March 2012
Mouse 'fat gene' gives clues on weight gain
NHS Choices: Behind the Headlines |  19 March 2012
Obesity gene's role revealed in mice study
BBC |  18 March 2012
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