Figure 3.

Small interference RNA (siRNA) for AQP4 diffuses within brain tissues. (A) Diffusion of nontargeted siRNA (siGLO) tagged with CY3 in a rat coronal section at the site of injection. CY3-siGLO (large arrow) was observed in the cortex at the site of injection and siRNA diffused within the brain parenchyma toward the contralateral striatum via the corpus callosum (CC, small arrows and inset box, higher magnification B2). The presence of siRNA was also detected at the surface (B1) of the ipsilateral and contralateral cortex (arrow heads) and within the ipsilateral striatum (not shown). (B) Confocal images (B1, B2, B3) of GFAP (green) and siGLO-CY3 (red) immunostaining at 3 days after the initial injection. (B1) Double staining revealed positive CY3 in astrocytes (arrows) around blood vessels and also in the glia limitans (arrowheads) in close proximity to the injection site. Several astrocytes were transfected by the tagged siRNA. (B2) In the CC, siRNA was detected in astrocytes (arrows), showing that the siRNA is able to diffuse via the CC to the contralateral hemisphere. (B3) Far from the injection site, siGLO-CY3 was observed in astrocytes in contact with blood vessels (arrows) within the contralateral striatum. GFAP, glial fibrillary acid protein.