Effects of various concentrations of glutamate on caspase-3 protein levels in primary cortical cells. Cortical cells isolated from 19 day old fetal rat brains were cultured for 7 days and treated with 1,5,10 and 20 mM glutamate for 6 h in a neurobasal medium containing 2% antioxidant free B27. Cells were then harvested and total protein was extracted. Caspase-3 protein levels were assessed by Western blot analysis as described under "Methods". Actin was used as loading control. The bars depict densitometric analyses of Western blots from at least three experiments (± SEM). *P < 0.05 compared with untreated control cells.