Thymosin [beta]4 prevents oxygen-glucose deprivation/reperfusion-induced injury in rat cortical neurons

Purpose: This study investigated whether thymosin (T) [beta]4 protects against oxygen-glucose deprivation/reperfusion (OGD/R) injury in rat cortical neurons, as well as the underlying mechanisms. Methods: Primary rat cortical neurons were transfected with T[beta]4 overexpression plasmid; the transfection efficiency was confirmed by detecting T[beta]4 expression by fluorescence quantitative PCR and Western blotting. The OGD/R model was established and apoptotic cells were quantified by flow cytometry and terminal deoxynucleotidyl transferase dUTP nick end labeling. Structural changes in the endoplasmic reticulum were visualized by transmission electron microscopy. The expression levels of 78-kDa glucose-regulated protein (GRP) 78, C/EBP-homologous protein (CHOP), B-cell lymphoma (Bcl)-2, and Bcl-2-associated X protein (Bax) were determined by Western blotting. The effect of T[beta]4 on OGD/R injury was evaluated by adding exogenous T[beta]4 to neuronal cultures. Results: Cortical neurons were identified by the expression of neuron-specific enolase. In OGD/R cells, the rate of apoptosis was increased and GRP78, CHOP, and Bax were upregulated whereas Bcl-2 was downregulated relative to the control group. These effects were reversed by T[beta]4 overexpression. Endoplasmic reticulum (ER) stress was observed in the OGD/R group, but this was abolished in neurons overexpressing T[beta]4. The protective effect of T[beta]4 against OGD/R injury was also demonstrated in cells treated with exogenous T[beta]4 (10 ng/mL), which blocked OGD/R-induced apoptosis by inhibiting ER stress-related and pro-apoptotic protein expression. Conclusion: T[beta]4 prevents OGD/R-induced ER stress-dependent apoptosis in cortical neurons, and is a potential treatment for cerebral ischemia-reperfusion injury. Keywords: T[beta]4, cortical neuron culture, OGD/R, endoplasmic reticulum stress