Propofol Protects Hippocampal Neurons from Hypoxia-Reoxygenation Injury by Decreasing Calcineurin-Induced Calcium Overload and Activating YAP Signaling.

Xiaojun Li,Hangyin Qu,Hui Cai,Qianlei Liang,Li Yao

doi:10.1155/2018/1725191

Abstract

Objectives Propofol is a popular anesthetic drug that is neuroprotective. However, the mechanisms of propofol for hippocampal neuroprotection remain elusive. This study is aimed at investigating the neuroprotective effect and mechanism of propofol in hippocampal neurons exposed to ischemia-reperfusion (I/R) injury. Methods Hypoxia-reoxygenated (H/R) HT-22 cells were used to mimic I/R injury of the hippocampus in vitro. An MTT assay was used to determine cell viability. Cell apoptosis was detected by a TUNEL assay and a flow cytometry cell apoptosis assay. Expression levels of proteins were measured by Western blotting. Intracellular calcium was assessed by Fura-2/AM staining. Flow cytometry was used to determine the mitochondrial membrane potential (MMP). Coimmunoprecipitation was used to evaluate the stability of the FKBP-RyR complex. Calcineurin enzymatic activity was measured with a colorimetric method. YAP nuclear translocation was tested by immunofluorescence staining. Results H/R induced HT-22 cell viability depression, and apoptosis was reversed by propofol treatment. Propofol could alleviate H/R-induced intracellular calcium accumulation and MMP loss by inhibiting calcineurin activity and FKBP12.6-RyR disassociation in a concentration-dependent manner. In addition, YAP expression was crucial for propofol to protect HT-22 cell apoptosis from H/R injury. Propofol could activate YAP through dephosphorylation. Activated YAP stimulated the transcription of the Bcl2 gene, which promotes cellular survival. Our data also demonstrated that propofol activated YAP through the RhoA-Lats1 pathway without large G proteins or MST involvement. In addition, we showed that there was no interaction between calcineurin signaling and YAP activation in HT-22 cells. Conclusions Propofol protected hippocampal neurons from I/R injury through two independent signaling pathways, including the calcineurin/FKBP12.6-RyR/calcium overload pathway and the RhoA/Lats1/YAP/Bcl-2 pathway.

Highlights

Ischemic stroke has become one of the leading causes of morbidity and mortality worldwide [1]
Propofol pretreatment dramatically improved the viability of HT-22 cells in a concentration-dependent manner (Figure 1(a))
We further tested the effects of propofol in cell apoptosis induced by H/R

Summary

Introduction

Ischemic stroke has become one of the leading causes of morbidity and mortality worldwide [1]. Reestablishment of blood supply for the ischemic region is the most effective approach [2]. Cerebral ischemia-reperfusion (I/R) injury after sudden recovery of blood supply, causing dysfunction of neurons, glia cells, and cerebral blood vessels, still threatens the survival of stroke patients [3]. Previous studies indicated that neuronal apoptosis was the associated mechanism of I/R injury, and the pyramidal neurons were found to be the most vulnerable neurocytes to I/R injury-induced apoptosis [4]. Numerous studies were conducted to prevent hippocampal neurons from I/R injury. Anesthetic drugs have been suggested to have neuroprotective effects on cerebral I/R injury via inhibiting cell apoptosis [5,6,7]

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Conclusion