An exciting study on mice emphasises the importance of exercise for people living with Parkinson’s.

Have you ever wondered what we can learn about exercise and the connection to Parkinson’s from mice? We are now aware that exercise is thought to effective in slowing the progression of Parkinson’s, but what can we learn about the benefits of irisin and how this naturally occurring polypeptide may change one of the hallmarks of Parkinson’s. Find out more here.  

For several years, exercise has been promoted as a new treatment for Parkinson’s and all clinicians involved in the care of people with Parkinson’s have ‘prescribed exercise’ as a method of delaying the progression of the condition. However, there has been little understanding of how this works at a cellular level.

 A recent study from John Hopkins University School of Medicine USA looked at the action of irisin, a small exercise-induced polypeptide secreted by skeletal muscle into the blood of mice and humans. Irisin levels increase in the blood of humans with exercise training.  

It has previously been recognised that irisin led to improved cognitive function and lower inflammation in a mouse model of Alzheimer’s which is also a neurodegenerative condition. The researchers motivated by the knowledge of the benefits of exercise looked at the action of irisin on alpha synuclein fibrils that are the hallmark of Parkinson’s. 

Initially, a cell model had been challenged by the addition of preformed fibrils of the alpha –synuclein protein - this prompted naturally occurring alpha-synuclein in the cells to misfold and accumulate as they do in Parkinson’s. They found that when this cell model was treated with irisin, the formation of toxic alpha-synuclein was prevented and the nerve cells were protected from dying. The team then injected preformed fibrils into the brains of mice to produce an animal form of Parkinson’s. Some of the mice were injected with irisin and some were not (a controlled study).

The results showed that the mice given irisin showed a 25% loss of cells compared with a 60% loss in the mice that did not receive the irisin. Irisin also prevented the turnover of dopamine – effectively increasing dopamine levels and blocked the accumulation of toxic alpha-synuclein. Importantly, motor symptoms usually associated with the Parkinson’s model were eased in the mice given the irisin but not in the untreated mice.

Other benefits of irisin were observed and the researchers are hopeful that further studies and translation into a human model will add to the body of knowledge that exercise can slow the progression of Parkinson’s. Until we have that knowledge, it seems basic common sense to introduce exercise into your daily routine.

References: Dawson, TM. et al. Amelioration of pathologic α-synuclein-induced Parkinson’s disease by irisin, 2022, PNAS Vol. 119, No 36 e2204835119