Catalpalactone protects rats nerve function from hypoxic lesion by polarizing microglial cells toward M2 phenotype.

Abstract

Background: Ischemic brain injury results in high disability due to neuroinflammation and oxidative stress, and M1/M2 polarization of glial cells plays a key role in neuroinflammation. This research explored the protective effect of Catalpalactone on middle cerebral artery occlusion (MCAO)-induced brain injury and its underlying regulation mechanism in rats.

Methods: The ischemic lesions were induced by the MCAO, and the oxygen and glucose deprivation/reoxygenation (OGD/R) was used for BV2 microglial cell induction. The polarization of glial cells was determined via immunohistochemistry staining assessment. Oxygen consumption rate (OCR) and extracellular acidification rate (ECAR) assays were used for the glycolysis and oxidative phosphorylation test. After that, the cell counting kit-8 (CCK-8) for cell viability test and flow cytometry for apoptosis and phosphorylation analysis were performed. Furthermore, a co-culture model of BV2 and PC12 cells was used for the purpose of exploring the effects of Catalpalactone on the interaction and of microglia and neurons in ischemic brain injury. Finally, the Modified Neurological Severity Score (mNSS) analysis was used for the analysis on the neurological function.

Results: After MCAO induction, the infiltration of microglial cells were significantly increased in the injury area, and its M1 phenotype was enhanced (up-regulated Cd86). In vitro, the OGD/R-induced BV2 microglial cell also exhibited the increasing M1 phenotype with higher glycolysis activity, but lower oxidative phosphorylation through the activating JAK-SATA signaling pathway. Finally, we determined that 15 μM Catalpalactone optimally induces M2 microglial polarization with increased cell viability and decreased apoptosis in the OGD/R-induced BV2 cell model, while also reducing mNSS scores and improving neurological function in the MCAO rat model.

Conclusion: We clarified the underlying mechanism of Catalpalactone treatment for ischemic lesions through promoting M2 microglial cells phenotype.