Figure 4

Substania nigra pars compacta (SNc) sections were stained with anti-Cd11b and rated on morphological appearance as marker for microglial state. Paraquat or poly(I:C) alone promoted a modest but non-significant elevation of microglial activation state relative to saline-treated controls. However, paralleling the TH + changes, poly(I:C) priming followed by later paraquat exposure significantly augmented signs of microglial activation. (A) Representative photomicrographs showing the degree of nigral microglial immunoreactivity induced by paraquat and poly(I:C) (note that the poly(I:C)-PQ image was taken from the group that received paraquat 2 days after poly(I:C) pre-treatment). (B) Quantification of ratings (arbitrary units) for microglial activation state. *P < 0.05, relative to saline-treated controls. Data expressed as mean ± SEM, n = 4 to 5.