Can irisin be a linker between physical activity and brain function?

Irisin was initially discovered as a novel hormone-like myokine released from skeletal muscle during exercise to improve obesity and glucose dysfunction by stimulating the browning of white adipose tissue. Emerging evidence have indicated that irisin also affects brain function. FNDC5 mRNA and FNDC5/irisin immunoreactivity are present in various regions of the brain. Central irisin is involved in the regulation of neural differentiation and proliferation, neurobehavior, energy expenditure and cardiac function. Elevation of peripheral irisin level stimulates hippocampal genes related to neuroprotection, learning and memory. In this brief review, we summarize the current understanding on neuronal functions of irisin. In addition, we discuss the pros and cons for this molecule as a potential messenger mediating the crosstalk between skeletal muscle and central nervous system during exercise.