Sources of reactive oxygen species production in excitotoxin-stimulated cerebellar granule cells

Reactive oxygen species (ROS) production in rat cerebellar granule cells in the presence of the excitotoxins N-methyl-D-aspartate (NMDA) and kainic acid (KA) and by the protein kinase C activator phorbol myristate acetate (PMA) was Ca²⁺-dependent and resulted in decreased cell viability. Exposure of stimulated cells to rotenone (a respiratory chain inhibitor) did not decrease ROS levels and did not affect short-term cell viability. In cells stimulated by NMDA and KA, exposure to indomethacin (a cycloxygenase inhibitor) and nialamide (a monoamine oxidase inhibitor) caused a decrease in ROS levels and increased cell viability occurred in NMDA-treated cells. In contrast, PMA-stimulated neurons did not show decreased ROS levels when exposed to indomethacin and nialamide. These studies suggest that there is a multiplicity of routes for Ca²⁺- dependent ROS production in neurons but that ROS generation by cyclooxygenase and monoamine oxidase is not controlled by protein kinase C.