Abstract
Reduced availability of reactive oxygen species is a key component of neuroprotection against various toxic stimuli. Recently we showed that the hydrogen peroxide scavenger catalase plays a central role in delayed preconditioning induced by the mitochondrial ATP-sensitive potassium channel opener BMS-191095. The purpose of the experiments discussed here was to investigate the neuroprotective effect of catalase in vitro using a recombinant adenoviral catalase gene transfer protocol. To induce catalase overexpression, cultured rat cortical neurons were infected with the adenoviral vector Ad5CMVcatalase and control cells were incubated with Ad5CMVntLacZ for 24 h. Gene transfer effectively increased catalase protein levels and activity, but did not influence other antioxidants tested. Ad5CMVcatalase, with up to 10 plaque forming units (pfu) per neuron, did not affect cell viability under control conditions and did not protect against glutamate excitotoxicity or oxygen-glucose deprivation. In contrast, catalase overexpression conferred a dose-dependent protection against exposure to hydrogen peroxide (viability: control, 33.02+/-1.09%; LacZ 10 pfu/cell, 32.85+/-1.51%; catalase 1 pfu/cell, 62.09+/-4.17%*; catalase 2 pfu/cell, 98.71+/-3.35%*; catalase 10 pfu/cell, 99.68+/-1.99%*; *p<0.05 vs. control; mean+/-SEM). Finally, the protection could be antagonized using the catalase inhibitor 3-aminotriazole. Our results support the view that enhancing cellular antioxidant capacity may play a crucial role in neuroprotective strategies.