Insulin-like growth factor 1 (IGF-1) has neuroprotective actions, including vasodilatory, anti-inflammatory, and antithrombotic effects, following
ischemic stroke. However, the molecular mechanisms underlying the
neuroprotective effects of
IGF-1 following
ischemic stroke remain unknown. Therefore, in the present study, we investigated whether
IGF-1 exerted its
neuroprotective effects by regulating the Hippo/YAP signaling pathway, potentially via activation of the PI3K/AKT cascade, following
ischemic stroke. In the in vitro study, we exposed cultured PC12 and SH-5YSY cells, and cortical primary neurons, to
oxygen-
glucose deprivation. Cell viability was measured using
CCK-8 assay. In the in vivo study, Sprague-Dawley rats were subjected to
middle cerebral artery occlusion. Neurological function was assessed using a modified neurologic scoring system and the modified neurological severity score (mNSS) test,
brain edema was detected by brain water content measurement,
infarct volume was measured using
triphenyltetrazolium chloride staining, and neuronal death and apoptosis were evaluated by TUNEL/NeuN double staining, HE and Nissl staining, and immunohistochemistry staining for NeuN. Finally, western blot analysis was used to measure the level of
IGF-1 in vivo and levels of YAP/TAZ, PI3K and phosphorylated AKT (p-AKT) both in vitro and in vivo.
IGF-1 induced activation of YAP/TAZ, which resulted in improved cell viability in vitro, and reduced neurological deficits, brain water content, neuronal death and apoptosis, and
cerebral infarct volume in vivo. Notably, the
neuroprotective effects of
IGF-1 were blocked by an inhibitor of the PI3K/AKT cascade,
LY294002.
LY294002 treatment not only downregulated PI3K and p-AKT, but YAP/TAZ as well, leading to aggravation of neurological dysfunction and worsening of brain damage. Our findings indicate that the
neuroprotective effects of
IGF-1 are, at least in part mediated by upregulation of YAP/TAZ via activation of the PI3K/AKT cascade following cerebral
ischemic stroke.