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A newly identified hormone that mimics the effects of exercise could one day help people lose weight and fight obesity-linked diseases without surgery.
Lab mice that were injected with this hormone lost weight and improved regulation of their blood sugar levels, which lowered their risk of diabetes, according to researchers in a new study. Normally the hormone, which the researchers have named irisin, builds up in the blood of people after doing months of endurance exercise.
The findings are detailed today (Jan. 11) in the journal Nature.
"This work represents a very important discovery because it has the potential of generating a new treatment" for obesity and its related diseases, such as Type 2 diabetes, said Sven Enerbäck, a geneticist specializing in obesity-related conditions at GöteborgUniversity in Sweden, who wasn't involved in the study.
Such diseases are an enormous health problem in many parts of the world, Enerbäcktold MyHealthNewsDaily.
Clues to this hormone's existence came from prior research conducted by Bruce Spiegelman, lead investigator of the new study. Spiegelman, who is a cell biologist at Dana-Farber Cancer Institute and Harvard Medical School, and his collaborators had found another protein whose levels increase after exercise, strengthening the muscles.
Like exercise itself, that protein had effects throughout the body. Mice with high levels of it were protected against obesity and diabetes.
"We knew the effect wasn't only limited to muscle," said study researcher Pontus Bostrom, a cell biologist at Harvard.
But what was not clear was exactly how exercised muscles communicate with the rest of the body to cause these widespread effects, Bostrom said. So the team searched for related proteins that were made by muscle cells, and found one that rose after endurance exercise and traveled through the bloodstream to other tissues.
They named it irisin, after the Greek messenger goddess Iris.
They found the hormone accumulated in the blood of mice after three weeks of running on a wheel, and in the blood of people after 10 weeks of endurance exercise.
When the team boosted irisin levels in mice through an injection, their fat cells consumed more oxygen and burned more calories.
The researchers next tested the hormone's effects in obese mice on a high-fat diet. They found the animals became slightly leaner within 10 days of being treated with a precursor to irisin.
These mice also showed an improved ability to regulate their blood sugar levels, which could help prevent diabetes, and the mice displayed no adverse reactions, according to the study.
Because the structure of irisin in mice and humans is identical, the hormone probably plays a similar role in us, Enerbäck said.
Moreover, the process of developing irisin into a drug could be faster and less complicated than with some other drugs because irisin is naturally produced in the body, he said. "If everything works as positive as possible, then I think it could be available six years from now."
This would be good news for those who have tried changing their diet and exercising more but still have been unable to lose weight, Enerbäck said. "This hormone could speed up that process and make it easier for people to achieve these goals once they have decided to change their lifestyle."
In the meantime, Bostrom said, there is "a vast set of questions to address." He and his collaborators will test whether long-term treatment with irisin can lead to more dramatic weight loss and improve other obesity-related conditions, such as hypertension and heart disease.
"In the future, we hope to be able to give this as a therapeutic to treat metabolic diseases, but there's a long road ahead," he said.
Pass it on: Irisin, a newfound hormone, may stimulate weight loss and improve health by mimicking the effects of exercise.