Immunohistochemical localization of sortilin and p75(NTR) in normal and ischemic rat retina.

In our previous study, we found the increased expression of p75(NTR) and sortilin by Western blotting in ischemic retina induced by elevated intraocular pressure (IOP). Cell specific expression of sortilin and p75 neurotrophin receptor (p75(NTR)) was now characterized in normal and ischemic rat retina induced by elevated IOP by double-labeling immunochemistry. Two patterns of sortilin staining in normal retina were identified: punctate and consistent. The former was seen in the retinal ganglion cell (RGC) bodies, probably in Golgi apparatus. The latter was found in astrocytes and Müller glial cells (MGCs). The expression pattern of sortilin did not change in ischemic state induced by elevated IOP. p75(NTR) was not found in RGCs, but in MGCs of most of the retinal layers, especially the inner plexiform layer (IPL), and outer plexiform layer (OPL) of normal retina. Taken together, the enhanced expression of sortilin in MGCs might be involved in the neuro-glial interactions in ischemic retina, but may not directly contribute to RGCs death through proNGF binding to complex receptor composed of sortilin and p75(NTR) in ischemic retina.