Figure 1.

Loss of dopaminergic neurons in the SN after repeated systemic challenges with LPS. A, Treatment and analysis paradigms. For the single treatment (left), mice were injected intraperitoneally once with 4 μg LPS/gbw and were analyzed on day 19. For the repeated treatment (right), mice were injected intraperitoneally on four consecutive days with 1 μg LPS/gbw and were analyzed on day 19. B, Immunofluorescence staining of the SN with antibodies directed against the dopaminergic cell specific marker protein TH (green) and neuronal nuclei marker protein NeuN (red) on experimental day 19 after repeated treatment with PBS control or LPS. Reduced staining of TH was detected in the SNpc after repeated systemic LPS challenge. Higher-magnification inset as indicated. Scale bar, 50 μm. Representative images for n ≥ 3 mice shown. C, Quantification of TH-positive (left) and NeuN-positive cells (right) in the SNpc of mice on experimental day 19 after systemic single or repeated challenge with PBS control or LPS. Only systemic repeated LPS application induced significant loss of TH-positive and NeuN-positive neurons. n ≥ 3 mice. n.s., Not significant. *p < 0.05. **p < 0.01. ***p < 0.001.