Exercise helps muscles and organs communicate
Researchers have shown, for the first time, why exercise has positive health effects across the entire body.
The new Australian research, published in the journal Cell Metabolism, reveals tiny protein-filled packages, called vesicles, are used by our muscles and other organs to communicate with each other during exercise.
Sydney’s Garvan Institute of Medical Research undertook the study in collaboration with researchers at the University of Sydney and the University of Copenhagen in Denmark.
The study identified thousands of different proteins that are released into vesicles in our bloodstream – including hundreds that appear to act as signals that we are exercising. Most of the proteins have never before been thought to be involved in communication within the body.
The study analysed the protein contents of vesicles in the blood of people before and immediately after exercise (an hour of cycling) and following a period of recovery. They found many more vesicles in the blood samples of people immediately after exercise than in those at rest or after recovery – and, importantly, many proteins enclosed within the vesicles were present in greater amounts after the exercise bout.
Professor Mark Febbraio, who heads Garvan’s Diabetes and Metabolism Division co-led the study. He believes this study showed that there’s the potential for a whole world of organ-to-organ messaging going on that has previously only been hinted at.
“We’re seeing a big burst of vesicles released when we exercise, and those vesicles contain a different mix of proteins – in other words, a different set of messages,” Professor Febbraio said.
“Until now, when researchers went looking for evidence of molecular communications from muscle, they would limit their search to a particular class of proteins, which are known to be released from cells into the bloodstream.”
The researchers believe the results have been startling.
Dr Martin Whitham, who also co-led the study, said that: “What we’re now seeing is over 5000 identified proteins in the blood that we think are packaged into vesicles – and importantly, only a small proportion (a fifth) of those proteins have a ‘postage stamp’.
“That means that there are 4000-plus proteins that have now been identified, that have not before been considered as being involved in organ-to-organ communication. It’s really going to change our thinking about how different parts of the body communicate, and what they ‘say’ to each other.”
When the researchers compared the vesicle proteome, they found that more than 300 proteins were significantly different between exercise and rest.
“We think these are the proteins that tissues such as muscles are sending out into the bloodstream, packaged into vesicles, when we exercise – so it’s fascinating to look at what those proteins are, and what the purpose of sending them into circulation might be,” Dr Whitham said.
Professor Febbraio explains that: “Broadly speaking, we think that tissues are likely to be sending messages that help other tissues respond to exercise and to reap its benefits – so this is an intriguing example where muscle or liver cells could send glycolytic enzymes rapidly to other organs, to help them deal with the increased energy demands that go along with exercise.
“It makes a lot of sense that many of these exercise-liberated vesicles may be emanating from muscle and heading to the liver, because we know that liver function is vastly improved by regular exercise.”