Vinpocetine Protects Against Cerebral Ischemia-Reperfusion Injury by Targeting Astrocytic Connexin43 via the PI3K/AKT Signaling Pathway.

Mingming Zhao,Di Ma,Liangshu Feng,Jiachun Feng,Pingping Shen,Famin Wang,Shuai Hou,Di Nan,Yunhai Zhang

doi:10.3389/fnins.2020.00223

Abstract

Vinpocetine (Vinp) is known for its neuroprotective properties. However, the protective mechanism of Vinp against cerebral ischemia/reperfusion (I/R) injury should be further explored. This study was designed to investigate the neuroprotective effects of Vinp against oxygen-glucose deprivation/reoxygenation (OGD/R) injury in vitro and cerebral I/R injury in vivo and explore whether this mechanism would involve enhancement of astrocytic connexin 43 (Cx43) expression via the phosphatidylinositol 3-kinase/protein kinase B (PI3K/AKT) pathway. In vitro, we detected astrocytic viability and extracellular nitric oxide by an assay kit, intracellular reactive oxygen species by a DCFH-DA probe, inflammation and apoptosis-related protein expression by immunofluorescence staining, and the astrocytic apoptosis rate by flow cytometry. In vivo, we measured the cerebral infarction volume, superoxide dismutase activity, malondialdehyde content, and the expression of inflammation and apoptosis-related proteins. The results indicated that Vinp ameliorated the detrimental outcome of I/R injury. Vinp attenuated astrocytic injury induced by OGD/R and reduced cerebral infarction volume and cerebral edema in rats with cerebral I/R injury. Moreover, Vinp reduced oxidative stress, inflammation, and apoptosis induced by cerebral I/R injury in brain tissues. Meanwhile, Vinp increased p-Cx43 and p-AKT expression, and the p-Cx43/Cx43 and p-AKT/AKT ratio, which was decreased by cerebral I/R injury. Coadministration of PI3K inhibitors LY294002 and BKM120 blunted the effects of Vinp. This study suggests that Vinp protects against cerebral I/R injury via Cx43 phosphorylation by activating the PI3K/AKT pathway.

Highlights

Ischemic stroke has high morbidity and mortality and seriously affects patient quality of life (Ribeiro et al, 2015)
Studies have shown that phosphorylation of AKT (Ser473) reduces neuronal apoptosis caused by cerebral I/R injury (Fukunaga and Kawano, 2003; Zhao et al, 2006), and LY294002-mediated inhibition of the PI3K/AKT pathway blocked the cardioprotective effect of atorvastatin against I/R injury in cardiocytes by downregulating Connexin 43 (Cx43) (Bian et al, 2015)
The results showed that approximately half of the astrocytes survived in oxygen-glucose deprivation/reoxygenation (OGD/R) group compared with the control group (56.86 ± 2.62%, P < 0.001)

Summary

Introduction

Ischemic stroke has high morbidity and mortality and seriously affects patient quality of life (Ribeiro et al, 2015). Effectively blocking the cascade of cerebral I/R injury and exploring effective drugs for the treatment of ischemic stroke are very important. Astrocytes are abundant in the central nervous system, and they play essential roles in maintaining brain function under physiologic conditions and in influencing neuronal survival under pathologic conditions, such as cerebral I/R injury and other brain insults (Garman, 2011; Falkowska et al, 2015; Verkhratsky et al, 2017). Astrocytes may be activated and produce and release reactive oxygen species (ROS), proinflammatory cytokines, and other factors that may negatively influence the survival of neurons in the penumbra (Swanson et al, 2004). Preventing astrocytic inflammatory and apoptotic effects may be a promising strategy for neuroprotection in ischemic stroke (Cekanaviciute and Buckwalter, 2016; Choudhury and Ding, 2016; Liu and Chopp, 2016)

Methods

Results

Conclusion