Written by: Matthew McQueen (Accredited Exercise Physiologist)
What is Irisin?
Irisin is a myokine (hormone), cleaved from the membrane protein FND5C via muscle contraction, first discovered in 2012. This hormone secreted from skeletal muscle during exercise and has previously been linked to thermoregulation and weight loss (1).
More recently it has been shown to protect against neurodegeneration and cognitive decline. With current research aiming to utilize these benefits shown from exercise as a therapeutic agent in the treatment of dementia (1).
Image Source: Molecular and Functional Interaction of the Myokine Irisin with Physical Exercise and Alzheimer’s Disease (2)
How does Irisin Protect the Brain?
It is well known that exercise has positive effects on brain health, making the identification of these mediator’s key. Irisin has shown, across four different experimental models, to rescue neurons that were functioning abnormally (1).
Indicating, that this exercise hormone could play a role in protecting against neurodegeneration after patients have become symptomatic reported Chrisiane QWarann (Program in Neuroprotection in Exercise, Massachusetts General Hospital) in and August 2021 press release (3).
Irisin Protecting Against Neuroinflammation
Another key finding of the study was that irisin protects against neuroinflammation via direct interaction on glial cells.
Glial cells can be categorized into 4 major groups 1) microglia 2) astrocytes 3) oligodendrocytes and 4) NG2-glia (4). With activated microglia cells triggering an inflammatory response, which is then amplified by astrocytes (5).
This further strengthens the importance of exercise to prevent cognitive decline and improve brain function. With evidence showing these exercise induced benefits are replicated in abnormally functioning neurons.
References:
- Islam MR, Valaris S, Young MF, Haley EB, Luo R, Bond SF, Mazuera S, Kitchen RR, Caldarone BJ, Bettio LE, Christie BR. Exercise hormone irisin is a critical regulator of cognitive function. Nature Metabolism. 2021 Aug;3(8):1058-70.
- Jin Y, Sumsuzzman DM, Choi J, Kang H, Lee SR, Hong Y. Molecular and functional interaction of the myokine irisin with physical exercise and Alzheimer’s disease. Molecules. 2018 Dec;23(12):3229.
- https://www.massgeneral.org/news/press-release/The-hormone-irisin-is-found-to-confer-benefits-of-exercise-on-cognitive-function
- Jäkel S, Dimou L. Glial cells and their function in the adult brain: a journey through the history of their ablation. Frontiers in cellular neuroscience. 2017 Feb 13;11:24.
- Takeuchi H. Roles of glial cells in neuroinflammation and neurodegeneration. Clinical and Experimental Neuroimmunology. 2013 Dec;4:2-16.