Exogenous Netrin-1 Inhibits Autophagy of Ischemic Brain Tissues and Hypoxic Neurons via PI3K/mTOR Pathway in Ischemic Stroke

Abstract Background and Objective: Ischemic stroke is a serious disease that endangers human health. How to reduce the damage of neurons in ischemic regions is an urgent problem to be explored. Autophagy is an important pathophysiological process in cerebral ischemia and Netrin-1 is an effective neuroprotective protein. This study aims to investigate the effect of Netrin-1 on autophagy of ischemic brain tissues and hypoxic neurons. Methods : We constructed rat persistent middle cerebral artery occlusion model in vivo and constructed the Oxygen Glucose-Deprivation model in vitro. Rats and cells were treated with or without Netrin-1. Western blot analysis was performed to detect autophagy related proteins LC3B, P62 and pathway related proteins PI3K, p-PI3K, mTOR, p-mTOR. CCK-8 assay was performed to detect the viability of hypoxic neurons. We also performed western-blot analysis and qRT-PCR test to detect levels of Netrin-1 protein and mRNA. Results : Autophagy enhanced both in ischemic brain tissues and hypoxic neurons. Netrin-1 inhibited autophagy through PI3K/mTOR pathway both in vivo and in vitro. At the same time, we found that exogenous Netrin-1 can promote the secretion of Netrin-1 protein by neurons themselves, which indicated that Netrin-1 can further amplify the neuroprotective effect through the positive feedback mechanism. Conclusions : Exogenous Netrin-1 alleviates damage of ischemic brain tissues and enhances viability of hypoxic neurons by inhibiting autophagy via PI3K/mTOR pathway. This effect can be amplified by positive feedback mechanism.