Figure 4.

MAO activity is increased in apoptotic PC12 cells. (A) Neuronal PC12 cells were incubated in the presence and absence of NGF (12, 24 or 48 h). The effect of addition of the irreversible MAO inhibitor clorgyline (10⁻⁷ M) was examined. Extracts were prepared from the cells, and MAO activity was measured. The data presented are the rates of 5-HT deamination (mean ± SD; n = 3) and are normalized to the rate of deamination measured in control neuronal PC12 cells. Similar data were obtained in three independent experiments. (B) Comparison of clorgyline (Clor) and deprenyl (Dep) on MAO activity in neuronal PC12 cell lysates. Clorgyline and deprenyl are selective inhibitors of the MAO isoforms A and B, respectively. The effect of different concentrations of the drugs on MAO activity was examined. The data presented are the rates of 5-HT deamination (mean ± SD; n = 3) and are normalized to the rate of deamination measured in control cell lysates. Similar data were obtained in three independent experiments.