FGF21 and brain injury: have identified FGF21 protected the heart from ischaemia‐reperfusion via controlling oxidative stress signalling.18 FGF21 is also a key mediator for glutamate‐induced excitotoxicity and D‐galactose‐induced ageing in the central nervous system (CNS).19, 20 Furthermore, it is reported that circulating FGF21 levels increased the injury lesion to promote remyelination after traumatic brain injury.21 However, little work has been done to explore FGF21 on nerve regeneration after PNI and clarify its underlying mechanisms.