Figure 3.

The figure shows the effects of pre-incubation with α-T for 0.5 and 18 h prior to PC12 cell exposure to 1 mM H₂O₂ for 3 h. (A) Pre-incubation with α-T at various concentrations for 0.5 h; (B) Pre-incubation with 100 nM and 100 μM α-T for 18 h. In this figure, the results of one typical experiment (from five experiments made) are presented as means ± SEM of 2–3 parallel determinations. The differences are significant by one-way ANOVA followed by Tukey’s multiple comparison test: * as compared to control values, p < 0.01; ^x as compared to the effect of H₂O₂ alone, p < 0.05; ^# as compared to the effect of α-T at all higher concentrations, p < 0.01. The data obtained provide evidence that pre-incubation with nanomolar α-T for 0.5 h prior to cell exposure to 1 mM H₂O₂ is not protective against H₂O₂-induced toxicity, while micromolar α-T is protective (A). However, if PC12 cells are pre-incubated with 100 nM or 100 μM α-T for 18 h and then exposed to 1 mM H₂O₂ (B) the protective effect of α-T in both concentrations is similar and significant (B).