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. 2012 Jul 31;287(39):32770–32779. doi: 10.1074/jbc.M112.377614

FIGURE 2.

FIGURE 2.

In vivo administration of PSTNm and donor substrate induces high levels of PSA expression in brain tissues. PSTNm and CMP-Neu5Ac were co-injected into the cerebral cortex, striatum, or spinal cord. Animals were perfused 24 h later and immunostained for PSA. Injection of enzyme alone produced no PSA in all three regions (A, D, and F; arrow, needle track). With co-administration of PSTNm and substrate, large amounts of PSA were detected in the cerebral cortex (B), and treatment with endo-N (C) completely abolished this staining (transverse sections). Although large portions of the striatum (transverse section) were polysialylated following injection of PSTNm and donor substrate (E), the dense bundles of myelinated fibers that traverse the striatum (stars) showed little or no PSA staining. High PSA expression was also observed in the spinal cord (G) (sagittal section), with good rostro-caudal as well as dorso-ventral extension of staining (SG, endogenous PSA in substantia gelatinosa). Scale bars, 100 μm in A–G. An example from the spinal gray matter (H) shows PSA staining in the neuropil (star) as well as on cell surfaces (arrows), with the cytoplasm of cells remaining devoid of PSA (dark). Arrowhead indicates a capillary. Scale bar, 50 μm. In the white matter, such as the corticospinal tract (I), PSA was readily visible on axons (arrows). Scale bar, 50 μm. J, view of a sagittal spinal section shows an example with good rostro-caudal spread of PSA staining, which sometimes exceeded 3 mm. Note the irregular shape of the stained area (double arrow indicates the extent of PSA staining. Dotted line, injection track. Scale bar, 100 μm). The bottom drawings are overlays of coronal maps (red, blue, green, and yellow) from four representative samples with cortical injection (K) and four samples with striatal injection (L) showing the variability in size and shape of the area of PSA expression among PSTNm/S-injected animals. Each color represents one sample. Cx, cerebral cortex; S, striatum; CC, corpus callosum; V, lateral ventricle.