Fig. 2

To assess the consequences of compression and decompression on cell apoptosis, sections were stained for Caspase-3. a-e Quantification of Caspase3-positive cells cranial, caudal and at the lesions sites demonstrated increased levels of apoptosis as a result of chronic cord compression at the lesion site (****p < 0.0001). Conversely, the number of apoptotic cells decreased significantly approaching normal levels following surgical decompression (****p < 0.0001). To assess neuronal pathology, sections were stained for APP. Quantification of APP+ axons in white matter tracts demonstrated a significantly increased APP expression as a consequence of compression (*p < 0.05, ****p < 0.0001), which subsided after decompression (***p < 0.001, ****p < 0.0001). Similarly, the number of APP+ but morphologically intact neurons in the grey matter increased as a result of compression cranial, caudal and at the lesions site (****p < 0.0001), and decreased following decompression to levels observed in controls (**p < 0.01, ***p < 0.001, ****p < 0.0001). In addition, the number of APP+ plaques in the grey matter significantly increased after decompression (*p < 0.05, **p < 0.001), but failed to decrease following decompression, indicating a sub-population of cells that was irreversibly damaged. Scale bar: c-h = 100 μm