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A new hormone has been discovered that is produced in muscles during exercise
Last reviewed: 01.07.2025
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Scientists at the Dana Farber Cancer Institute say they have isolated a previously unknown hormone found in muscle cells. They believe the protein acts as a chemical messenger in triggering many key processes in the body during exercise.
Study authors Bruce Spiegelman and Pontzky Bostroem said: "We were thrilled to discover a natural substance produced during exercise that has clear therapeutic potential."
The hormone, which Spiegelman calls "Irisin," could open the door to treatments for people with diabetes, obesity, and possibly other diseases, including cancer. Scientists are just beginning to understand how exercise positively changes the body's physiology, and further research could harness those mechanisms to fight disease.
Spiegelman said: "We knew that exercise affected all tissues of the body... But the question was, how?"
One of irisin's most powerful effects is the conversion of white fat cells into brown fat, which is considered the best type of fat. Irisin also improves glucose tolerance, a key indicator of metabolic health. The tests were conducted on mice, but the scientists are confident that the observations can be translated into human physiology.
Spiegelman's team found the hormone irisin by searching for genes and proteins that are regulated by a substance called PGC1-alpha. In previous studies, they found that PGC1-alpha is activated by exercise.
Pontsky Bostroem said the search for a molecular cause of the increased activity of PGC1alpha eventually landed on irisin, which turned out to be located on the outer membrane of muscle cells. This discovery contradicted the consensus of scientists, who had previously believed that the protein was located in the cell nucleus.
To test the link between exercise and increased levels of the hormone irisin, the scientists injected the hormone into mice that were obese and pre-diabetic. After 10 days of treatment, the scientists saw that the mice had improved blood sugar and insulin levels, effectively preventing the development of diabetes. They also lost a small amount of weight. Although the weight loss was small, Spiegelman says the hormone would have a greater effect if the treatment had been continued longer. Additionally, irisin was non-toxic, as the scientists limited the hormone levels to those seen with exercise.
However, taking irisin supplements will not increase muscle mass, as the increase in hormone levels will only be apparent after regular and prolonged exercise.
Spiegelman said irisin-based drugs could be available in the next two years and could have a significant impact on the treatment of a range of diseases, including neurodegenerative diseases such as Parkinson's.
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