Basic Fibroblast Growth Factor Protects Astrocytes Against Ischemia/Reperfusion Injury by Upregulating the Caveolin-1/VEGF Signaling Pathway

Abstract

A previous in vivo study demonstrated that intracerebroventricular injection of basic fibroblast growth factor (bFGF) in middle cerebral artery occlusion rats increased the expression of caveolin-1 (cav-1) and vascular endothelial growth factor (VEGF) in cerebral ischemia penumbra. Because astrocytes are the largest population in the brain, the aim of this in vitro study was to investigate the influence of bFGF on cav-1 and VEGF expression in rat astrocytes following oxygen glucose deprivation/reoxygenation (OGD/R). For this, an ischemic model in vitro of oxygen glucose deprivation lasting for 6 h, followed by 24 h of reoxygenation was used. Primary astrocytes from newborn rats were pre-treated with siRNA targeting bFGF before OGD/R. Cell viability was measured by a CCK-8 assay. The protein and mRNA expressions of bFGF, cav-1, and VEGF were evaluated by western blotting, immunofluorescence staining, and reverse transcription-quantitative polymerase chain reaction. The results showed that OGD/R reduced cell viability, which was decreased further following bFGF knockdown; however, restoring bFGF improved cell survival. A cav-1 inhibitor abrogated the effect of bFGF on cell viability. The expression levels of bFGF mRNA, bFGF protein, cav-1 mRNA, cav-1 protein, and VEGF protein were higher in OGD/R astrocytes. bFGF knockdown markedly decreased the expression levels of cav-1 mRNA, cav-1 protein, and VEGF protein, which were effectively reversed by exogenous bFGF treatment. Moreover, exogenous bFGF treatment significantly increased the expression levels of cav-1 mRNA, cav-1 protein, and VEGF protein in OGD/R astrocytes; however, a cav-1 inhibitor abolished the effect of bFGF on VEGF protein expression. These results suggested that bFGF may protect astrocytes against ischemia/reperfusion injury by upregulating caveolin-1/VEGF signaling pathway.

Keywords: Basic fibroblast growth factor; Caveolin-1; OGD/R; Primary astrocytes; Vascular endothelial growth factor.