Neuroprotective Effects Of FK506 Against Retinal Ganglion Cell Death Induced By Elevated Intraocular Pressure In Rat

Purpose: Glaucoma affects more than 66 million people worldwide and is the leading cause of irreversible blindness. The feature of all the patients is the progressive death of retinal ganglion cell (RGC).The elevated intraocular pressure (IOP) is the principal risk factor for the development of glaucoma. The most important glaucoma therapy is lowering IOP, but some patients with normal IOP can not completely stop the RGC death and the visual loss. Consequently, Neuroprotective strategies have been heralded as an adjunctive approach to lowering of IOP. We investigated whether FK506 can attenuate RGC death induced by elevated IOP.Methods: IOP elevation was induced in the right eyes of 30 Wistar albino rats by argon laser irradiation of the trabecular meshwork 4 days after an intracameral injection of India ink. The left eye served as a control. We injected intraperitoneally Saline 1.5ml, 0.3, or 1.0 mg. kg-1. bw-1 of FK506 before the laser application. Five days later, 3μl of 3% Fast Blue was injected into the superior colliculi bilaterally. Three days after the Fast Blue injection, the eye was enucleated and the retinal whole flat mounts was prepared. Labeled ganglion cells in the area 1 mm away from the optic disc were counted by fluorescence microscope with an ultraviolet filter.Results: (1)Five days after laser application, no significant IOP change in the right eye was found among the 3 groups. (2)In eyes treated with FK506, significantly more ganglion cells were labeled.Conclusion: FK506 appears to have a neuroprotective effect on retinal ganglion cells in this elevated intraocular pressure model.