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 deri ved from the brains of newborn rats was investigated by double-labelling im munocytochemical staining. Strong catalase immunoreactivity was found in ce lls positive for glial fibrillary acidic protein and galactocerebroside, ce llular 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 contra st, after inhibition of glutathione peroxidases by mercaptosuccinate the ra te of the catalase-dependent disposal of H2O2 declined with time and after about 10 min the extracellular concentration of H2O2 remained almost consta nt at a concentration of about 100 muM. Catalase activity after 10 min of i ncubation under these conditions was no longer detectable. In contrast, in the absence of mercaptosuccinate catalase activity was maintained during H2 O2 disposal. These results demonstrate that in astroglia-rich cultures cata lase is strongly expressed in the predominant astroglial cells and in the m inor population of oligodendroglial cells and that the enzyme is rapidly in activated during the disposal of H2O2, if the glutathione system of the cel ls is compromised. (C) 2001 Elsevier Science Ireland Ltd. All rights reserv ed.