Influence of nucleotide analogues 8-Br-cAMP, 8-Br-cGMP, and the PKC activator TPA on glial cell viability. (A) The highest concentration of 500 μM of the cGMP analogue 8-Br-cGMP had no significant effect on cell viability of olfactory ensheathing cells and Schwann cells. Schwann cell showed a slightly decreased viability (86% of control) which was not significant. (B) OB-OECs and OM-OECs showed no significant difference between viability of controls at a concentration of 500 μM 8-Br-cAMP. Schwann cells showed a significant decrease in cell viability of 81% compared to controls. (C) Cell viability of all three cell types was not significantly decreased at 100nM TPA treatment in comparison with control. Histograms present the means ± SEM of 3 separate experiments with at least three wells per experiment. Statistical analysis was performed using an ANOVA and the Newman-Keuls post-hoc test (*p < 0.05).