With increasing awareness of Americans’ obesity, researchers have been working to discover new ways to treat the condition. Recently, Obstetrics and Gynecology Prof. Aaron Hsueh and his team of researchers discovered the hormone obestatin, which may help to provide some answers to this growing problem.

On Nov. 11, the journal Science published the research on obestatin conducted by Jian V. Zhang, a postdoctoral fellow in obstetrics and gynecology who works in Hsueh’s laboratory. Zhang is the lead author of the paper, and Johnson and Johnson Pharmaceutical Research and Development, LLC, sponsored the research.

According to Hsueh, the discovery of the appetite-inducing hormone ghrelin in 1999 gave researchers hope that they had found a way to successfully fight obesity. But after many tests, the removal of the hormone failed to provide the weight-loss response researchers were hoping for.

Obestatin is part of a category of hormones that consists of small protein molecules named peptide hormones, says a Stanford News Service article published Nov. 11. These hormones provide easy targets for the drug developers because they are easily bound to G-protein-coupled receptors (GPCRs).

GPCRs “represent targets for almost 50 percent of the drugs in the market,” Hsueh told the Stanford News Service.

One particular tool that helped Hsueh and his team of researchers isolate obestatin were data collected from the Human Genome Project, an initiative that — among other goals — aimed to identify as many genes in human DNA as possible and store them in a database. The project was completed in 2003.

Hsueh’s team analyzed some of the gene sequences in the database and found that humans and fish have a common ancestor that had a gene to control hunger. This ancestor’s gene caused it to feel hunger no matter how much it ate.

As an example of this characteristic, Hsueh says, “You can feed goldfish to death, and they’ll keep eating and never feel full.”

As organisms evolved from this common ancestor, they became more capable of deciding whether or not to eat, according to Hsueh. Eventually, they could feel full when they’d eaten enough.

While they were comparing the ancestor’s gene sequences with those of other species, Hsueh and his team located obestatin. According to Zhang, the hormone was discovered mainly because it was a gene that was “preserved” through the evolution of this ancestor.

Hsueh says the most surprising finding is that obestatin — which suppresses hunger — was found in the same gene that holds ghrelin, a substance traditionally thought to help control body weight. The discovery of two hormones on one gene sequence is an incredibly rare occurrence, Hsueh says. The fact that this particular sequence holds both ghrelin and obestatin, two opposing hormones, is in fact remarkable.

The two hormones work together to control appetite, according to the Stanford News Service. As an organism eats, ghrelin informs the body that it needs food, whereas obestatin quells hunger when the body is full. Removal of the gene would eliminate both hormones as well as their effects.

“When we inject obestatin into a ventricle, we can see the effect almost immediately,” Hsueh explains. “It decreases food intake. The command for this action might come from the brain, or it could be produced locally, we don’t know. However, when we inject it into the whole animal, we see a decrease in food intake. When we take the small intestine out and look at [its] spontaneous contractions, you can add obestatin. When the intestine does not contract, the food will not move down. Therefore, you feel full already because [the food] stays right there.”

Zhang adds that obestatin seems like it could be an effective cure for obesity because when it was injected into mice, they found “that the peptide decreased the body weight of the mice by 10 to 20 percent after long term injections.”

And Hsueh says that “there are more than a dozen hormones regulating the overall process of eating. The discovery of obestatin is part of a bigger puzzle, especially for [those with] extreme obese situations. I think psychology is a major influencer in this and the discovery of obestatin is not going to solve those psychological issues.”

Zhang says she agrees that “lots of things can affect appetite. A sad mood can affect appetite. We have to test whether it really is the peptide and not some other influencing factor. We have to further test these possibilities.”

According to Zhang, the team is working on a treatment for obesity. Hopefully obestatin can help in the development of drugs that will one day reduce unhealthy cases of obesity across the country.