Figure 7. Caspase-8 deficiency protects the nigro-striatal dopaminergic system against the MPTP-induced neurodegenerative changes. Illustration of tyrosine-hydroxylase (TH) immunoreactivity in substantia nigra (a) and striatum (c) in response to either saline or MPTP in Casp8fl/fl and CreLysMCasp8fl/fl mice. Stereological quantification of TH-labeled neurons of each condition is shown in (b). There was less loss of nigra dopaminergic neurons in response to MPTP in CreLysMCasp8fl/fl mice, this effect being close to statistical significance. Analysis of integrity of striatal dopaminergic nerve endings (d) demonstrated significantly less MPTP-induced loss of TH immunoreactivity in CreLysMCasp8fl/fl mice as compared with Casp8fl/fl mice (p <0.05). Scale bar: a: 400 μm; c: 500 μm.