The Neuroprotection Of Caveolin-1 On Oxygen-glucose Deprivation-induced Injury In Cultured Astrocytes

Objective:Caveolin-1 (Cav-1) is the main structural protein of caveolae, the micro-invaginations of the plasma membrane. Cav-1 has been shown to be associated with many signaling molecules involved in the impaired neurovascular coupling after stroke, however, its direct role in the ischemic brain damage remains unclear. In the present study, we examined the Cav-1 expression in astrocytes and its role in oxygen-glucose deprivation (OGD).Methods:Primary astrocytes were cultured from forebrains of 24-hour-old rats. After initial purification, astrocytes were exposed to OGD for 6 h followed by reoxygenation. The expression of Cav-1 in astrocytes was assessed by double immunofluorescence staining with glial fibrillary acidic protein (GFAP). Real-time PCR and Western blot (WB) were used to determine the influence of OGD on the Cav-1. To further elucidated the role of Cav-1 in the ischemic insult, we down-regulated the Cav-1 mRNA level using Cav-1 siRNA or overexpression Cav-1 with Caveolin-1 scaffolding domain peptide (C1-SD82-101) in astrocytes, and compared their susceptibility against OGD injury with naive astrocytes. We detected the level of extracellular signal-regulated kinase 1/2 (ERK1/2) and phosphorylated extracellular signal-regulated kinase 1/2 (pERKl/2) in astrocytes by Western blot and examined the survival rate of astrocytes after blocking ERK1/2 signaling by MEK inhibitor U0126.Results:Cav-1 was expressed in all the cultured astrocytes. After OGD exposure, Cav-1 transcription was decreased by 32.83% at 24 h after reoxygenation, as compared with the normoxic cells. WB results confirmed that Cav-1 expression also significantly declined at 48 h after OGD. When treated with Cav-1 siRNA, the cell death of astrocytes was dramatically deteriorated after OGD compared with those cells pretreated with scrambled siRNA. Meanwhile, we found that the survival rate of cells which pretreated with C1-SD82-101 was raised and the expression of pERKl/2 in those cells significantly increased; however, MEK inhibitor (U0126) could block Cav-1-induced neuroprotection.Conclusion:These results suggested that Cav-1 represent a protective role in the astrocytes in ischemic injury, and ERK1/2 pathway maybe involved in Cav-1-induced neuroprotection.