Calycosin alleviates cerebral ischemia/reperfusion injury by repressing autophagy via STAT3/FOXO3a signaling pathway

Abstract

Background: As a common cerebrovascular disease (CVD) of the elderly, ischemic stroke (IS) is characterized by high disability and mortality. Excessive autophagy induced by IS is implicated in neuronal death, therefore, the inhibition of immoderate autophagy is viewed as a potential therapeutic avenue to treat IS. Calysoin (CA) is a bioactive component of Radix Astragali, which has been widely used to treat CVDs. However, the mechanism of the treatment of IS by CA is still problematic.

Purpose: Based on the result of network pharmacology, whether CA inhibited autophagy by regulating the STAT3/FOXO3a pathway to alleviate cerebral ischemia-reperfusion injury (CIRI) was investigated in vivo and in vitro for the first time.

Study design: Integrate computational prediction and experimental validation based on network pharmacology.

Methods: In current study, network pharmacology was applied to predict the mechanism of the treatment of IS by CA, and it was shown that CA alleviated CIRI by inhibiting autophagy via STAT3/FOXO3a signaling pathway. One hundred and twenty adult male specific pathogen-free Sprague-Dawley rats in vivo and PC12 cells in vitro were used to verify the above prediction results. The rat middle cerebral artery occlusion/reperfusion (MCAO/R) model was established by suture method, and oxygen glucose deprivation/re-oxygenation (OGD/R) model was used to simulate cerebral ischemia in vivo. The content of MDA, TNF-α, ROS and TGF-β1 in rat serum were detected by ELISA kits. The mRNA and protein expressions in brain tissue were detected by RT-PCR and Western Blotting. The expressions of LC3 in brain were detected immunofluorescent staining.

Results: The experimental results demonstrated that administration of CA dosage-dependently improved rat CIRI as evidenced by the reduction in the cerebral infarct volume, amelioration of the neurological deficits. HE staining and transmission electron microscopy results revealed that CA ameliorated cerebral histopathological damage, abnormal mitochondrial morphology, and damaged mitochondrial cristae structure in MCAO/R rats. CA treatment exerted protective effects in CIRI by inhibiting inflammation response, oxidative stress injury, and cell apoptosis in rat and PC12 cells. CA relieved excessive autophagy induced by MCAO/R or OGD/R through downregulating the LC3Ⅱ/LC3Ⅰ ratio and upregulating the SQSTM1 expression. CA treatment also decreased p-STAT3/STAT3 and p-FOXO3a/FOXO3a ratio in the cytoplasm and modulated the autophagy-related gene expression both in vivo and in vitro.

Conclusion: Treatment with CA attenuated CIRI by reducing excessive autophagy via STAT3/FOXO3a signal pathway in rat and PC12 cells.

Keywords: Autophagy; Calycosin; Cerebral ischemia/reperfusion injury; Network pharmacology; STAT3/FOXO3a signal pathway.