Study on histopathological mechanism of regeneration of optic nerves in rats

Background Many researches have showed that injury of lens can induce the regeneration of optical nerve and survival of retinal ganglion cells (RGCs).However,its mechanism is below understood.Objective The purpose of this study was to investigate the histopathological mechanism of regeneration of optical nerves.Methods Forty health clean adult Wistar rats were divided into randomly normal group(n=8),only optical nerve injury group(n=16) and optical nerve injury combined with lens injury group (n=16).The optical nerve was cut to create the across cutting but the central vessel in nerve was remained in the optical nerve injury models.Lens was punctured with needle simultaneously in the rats of combined injury group.Animals were sacrificed after 4 weeks.4-5 μL (2.5%) RITC was injected into vitreous cavity of rats via glass capillary in 3 days before sacrificed.The optic nerves and retinaes were observed histopathologically by hematoxylin eosin staining and retinal RGCs were counted.Results Normal optical nerve fibers and nervous glial cells were found in normal rats.In only optical nerve cutting group,cluster glial scar with dense and disorder astrocytes in the distal and proximal stumps of optic nerves were seen.In contrast,less astrocytes were found.There was no glial scar in the distal and proximal stumps,but plenty of macrophages infiltrating could be displayed in the combined injury group of optical nerve and lens.The number of peripheral RGCs in combined injury group of optical nerve and lens group was 25.00±1.49,and that of only optical nerve injury group was 4.06±1.45,showing a significant difference between them(P0.01).Conclusion To overcome the glial scar as a physical barrier between two stumps of the optic nerves and enhance the numbers of RGCs are the key links in the regeneration of optic nerve.