Neuritin improves the neurological functional recovery after experimental intracerebral hemorrhage in mice

Stroke is one of the leading causes of death worldwide, with intracerebral hemorrhage (ICH) being the most lethal subtype. Neuritin (Nrn) is a neurotropic factor that has been reported to have neuroprotective effects in acute brain and spinal cord injury. However, whether Nrn has a protective role in ICH has not been investigated. In this study, ICH was induced in C57BL/6 J mice by injection of collagenase VII, while the overexpression of Nrn in the striatum was induced by an adeno-associated virus serotype 9 (AAV9) vector. We found that compared with GFP-ICH mice, Nrn-ICH mice showed improved performance in the corner, cylinder and forelimb tests after ICH, and showed less weight loss and more rapid weight recovery. Overexpression of Nrn reduced brain lesions, edema, neuronal death and white matter and synaptic integrity dysfunction caused by ICH. Western blot results showed that phosphorylated PERK and ATF4 were significantly inhibited, while phosphorylation of Akt/mammalian target of rapamycin was increased in the Nrn-ICH group, compared with the GFP-ICH group. Whole cell recording from motor neurons indicated that overexpression of Nrn reversed the decrease of spontaneous excitatory postsynaptic currents (sEPSCs) and action potential frequencies induced by ICH. These data show that Nrn improves neurological deficits in mice with ICH by reducing brain lesions and edema, inhibiting neuronal death, and possibly by increasing neuronal connections.