Evolving neurovascular relationships in the RCS rat with age

Abstract

Purpose. To examine the course of development of vascular disorders in the Royal College of Surgeons (RCS) rat and how these may lead to retinal ganglion cell loss. Methods. Whole-mount retinae from RCS rats were first stained for neurofilament protein and then for NADPH-diaphorase staining. A separate group of RCS rats was injected with Type II Peroxidase and the retinae were subsequently processed for peroxidase histochemistry. Results. The first changes in the deep vascular plexus occur as the photoreceptor layer is lost and it comes into close proximity to the retinal pigment epithelial (RPE) cell layer. RPE cells migrate onto retinal vessels, and at such locations vascular complex develop. These are first found ventral to the optic nerve head and then gradually progress over most of the retina. The inner retinal vessels that supply the complexes cross the optic nerve fiber layer and appear to be under tension. They ligate axons, which leads to retinal ganglion cell loss. Conclusions. These observations show vascular changes can have secondary repercussions for neurons distant from the primary lesion.