Catalase in astroglia-rich primary cultures from rat brain: immunocytochemical localization and inactivation during the disposal of hydrogen peroxide

The expression of catalase in cells of astroglia-rich primary cultures derived from the brains of newborn rats was investigated by double-labelling immunocytochemical staining. Strong catalase immunoreactivity was found in cells positive for glial fibrillary acidic protein and galactocerebroside, cellular markers for astroglial and oligodendroglial cells, respectively. The cells of these cultures dispose of exogenously applied hydrogen peroxide (initial concentration 200 muM) quickly with first order kinetics. In contrast, after inhibition of glutathione peroxidases by mercaptosuccinate the rate of the catalase-dependent disposal of H2O2 declined with time and after about 10 min the extracellular concentration of H2O2 remained almost constant at a concentration of about 100 muM. Catalase activity after 10 min of incubation under these conditions was no longer detectable. In contrast, in the absence of mercaptosuccinate catalase activity was maintained during H2O2 disposal. These results demonstrate that in astroglia-rich cultures catalase is strongly expressed in the predominant astroglial cells and in the minor population of oligodendroglial cells and that the enzyme is rapidly inactivated during the disposal of H2O2, if the glutathione system of the cells is compromised. (C) 2001 Elsevier Science Ireland Ltd. All rights reserved.