Fig. 3

Toxicity of SN DA neurons by MPP⁺ is exacerbated in the presence of regional microglia and is alleviated by inhibition of microglial activation. a The addition of regionally isolated microglia (SN, VTA, CTX) to cultures of SN DA neurons and astrocytes demonstrates that the addition of microglia themselves is not deleterious to these neurons. However, coupled with MPP⁺ treatment, all regionally isolated microglia cause exacerbation of toxicity to a similar extent; one-way ANOVA with Bonferroni’s post hoc multiple comparisons test; F (7, 16) = 84.2, ****p < 0.0001. b TLR4 inhibitor C34 (light purple) does not cause any degeneration of SN DA neurons in culture. However, a significant decrease in the exacerbation of MPP⁺ toxicity is observed when microglial activation is inhibited by the drug (red compared to purple); one-way ANOVA with Tukey’s post hoc multiple comparison test; F (3, 14) = 144.4, ****p < 0.0001