Glutamate-induced c-Jun Expression in Neuronal PC12 Cells

Abstract

Transcription factor c-Jun affects neuronal cell death and survival in mammalian brain. As general anesthetics, such as ketamine and propofol, are thought to provide some degree of neuroprotection, this study was intended to test whether the protection of injured neuronal PC12 cells by ketamine and propofol is related to the inhibition of phospho-c-Jun. Using neuronal PC12 cells from rat pheochromocytoma cells differentiated with nerve growth factor, we found that 24 hours of exposure to glutamate (1 to 100 mM) induced concentration-dependent cell death as determined by an ability to reduce the tetrazolium derivative, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) into a blue formazan salt. Neuronal PC12 cells were exposed to ketamine (0.1, 1.0 mM) or propofol (0.5, 5.0 microM) and glutamate (0, 20 mM) for 24 hours. Cell injury was assessed using MTT, in situ terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate-biotin nick end labeling, and c-Jun activity assay. Glutamate, 20 mM, induced about 70% of cell death as determined by MTT and terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate-biotin nick end labeling staining. Glutamate-induced cell death was related to an increase in expression of phospho-c-Jun. Glutamate-induced cell death was reduced by ketamine (0.1, 1.0 mM) in a dose-dependent manner and also by propofol (0.5, 5.0 microM). In addition, the expression of phospho-c-Jun was substantially reduced by ketamine (0.1, 1.0 mM) and propofol (0.5, 5.0 microM), respectively, as determined by Western blot assay. These results suggest that inhibition of c-Jun activity is involved in the neuroprotective effects of ketamine and propofol on glutamate-induced injury in neuronal PC12 cells.