Fig. 4

CCR2-GFP reporter mice reveal early but limited nigral infiltration of CCR2⁺ monocytes during MPTP mediated DA neurodegeneration. a–c Timecourse analysis of appearance of CCR2-GFP⁺ cells (stained with anti-GFP antibodies, brown, arrows), at 24 h (b) and 36 h (c) after acute MPTP intoxication within the SNpc of CCR2-GFP mice and compared to saline injected controls (a). Compared to only very rare CCR2⁺ cells detectable in controls, multiple CCR2-GFP⁺ cells are detected at 36 h, (see magnification insets in b and c). d Quantification of CCR2-GFP⁺ cells within the SNpc at 12 h (n = 3), 24 h (n = 5), 36 h (n = 4), 48 h/2 days (n = 5), 4 days (n = 4), and 7 days (n = 6) after MPTP intoxication in CCR2-GFP mice (compared to saline injected controls; CON, n = 3), suggesting early but limited CCR2⁺ monocyte infiltration, with a peak at 36 h, then returning to baseline levels after 4/7 days. Counts represent the estimated total of CCR2-GFP⁺ cells within the entire SNpc (means +/− SEM; n = 3–6 mice per condition; *P = 0.048, ***P < 0.001; Kruskal-Wallis test). e Immunofluorescence stains in the SNpc of CCR2-GFP mice at 36 h after MPTP intoxication, showing colocalization of CCR2-GFP⁺ cells with myeloid markers CD11b and Iba1 (insets for magnification), beside resident GFP negative microglia (arrowhead) (Scale bars; C, 200 μm, with 10 μm in insets; E, 10 μm)