Sydney, Feb 14 (IANS): Researchers have found that a gene that controls food intake by triggering a feeling of fullness could help break the cycle of overeating and under-exercising, a study says.

The finding may lead to the development a drug that could help control obesity by reducing appetite and increasing the desire for exercise, according to the researchers.

In the study, published in the journal Proceedings of the National Academy of Sciences, the researchers reported discovery of the gene, encoding a transcription factor called ETS-5, which controls signals from the brain to the intestines.

The discovery of ETS-5 is the first time a gene regulatory molecule of this type, and potential drug target, has been implicated in the brain-intestinal control of eating and activity, said one of the researchers Roger Pocock, Associate Professor at Monash University in Melbourne, Australia.

The researchers discovered the gene in worms, but they noted that a similar gene is found in people.

"The ETS family of genes is present in humans and has previously been linked to obesity regulation. Now that we've learned this gene family controls food intake through a feedback system to the brain, it represents a credible drug target for the treatment of obesity," Pocock said.

The researchers studied Caenorhabditis elegans, or the roundworm, because of the comparative simplicity of its brain -- it has just 302 neurons and 8,000 synapses, or neuron-to-neuron connections, all of which have been mapped.

The roundworm and humans share up to 80 per cent of their genes, as well as around half of all the known genes which are involved in human diseases, Pocock said.

"Because roundworms share so many genes with humans they are a great model system to investigate and gain a better understanding of processes like metabolism as well as diseases in humans," he said.

The researchers discovered the role of the transcription factor ETS-5 by analysing single neurons within the brain of the worm, monitoring its response to food.