Figure 10.

Immunohistochemical evidence of enhanced calpain activity in nigral neurons in postmortem human tissues. A, Immunohistochemical detection of calpain-cleaved α-spectrin (38-4) viewed at low (20×) magnification revealed intense clusters of immunopositive staining in PD cases that were rarely observed in control cases. B, C, Confocal optical sectioning (0.6 μm) of calpain-cleaved α-spectrin immunoreactivity in pigmented dopamine neurons from a case without neurological condition (B) and from a case with Parkinson's disease (C) further revealed the cytoplasmic speckled appearance of 38-4-immunopositive staining that colocalized with neuromelanin (insets). D, Quantification of the proportion of pigmented neurons per section that displayed speckled calpain-cleavedα-spectrin immunoreactivity from PD and control tissues revealed a significant increase in calpain activity in subjects with PD (**52.83 ± 7.5 vs 9.17 ± 3.1%; Mann-Whitney rank-sum test; p = 0.0079). Positive immunostaining disappeared when the primary antibody was omitted (data not shown). Scale bars: A,25μm; B, C,50μm.