Protective effects of systemic treatment with methylprednisolone in a rodent model of non-arteritic anterior ischemic optic neuropathy (rAION)

- Methylprednisolone increases RGC survival rate in both central retinas and mid-peripheral retinas in rAION.
- Methylprednisolone preserves FVEP in rAION.
- The rescue effects from methylprednisolone through the dual actions of anti-apoptosis and anti-inflammation.

This study investigated the protective effects of the administration of steroids on optic nerves (ON) and retinal ganglion cells (RGCs) in a rodent model of non-arteritic anterior ischemic optic neuropathy (rAION). We induced rAION using rose bengal and argon laser irradiation in a photodynamic procedure on the optic discs of rats. The treated groups received methylprednisolone (MP) via peritoneal injection for 2 weeks. The control group received intraperitoneal injections of phosphate-buffered saline (PBS) post-rAION. At the 4th week post-infarct, MP treatments significantly rescued the RGCs (mm2) in the central retinas (1920 ± 210, p < 0.001) and mid-peripheral retinas (950 ± 240, respectively, p = 0.018) compared with those of the PBS-treated rats (central: 900 ± 210 and mid-peripheral: 440 ± 180). Functional assessment with flash visual-evoked potentials demonstrated that P1 latency (ms) was shortened in the MP group compared to the PBS group (108 ± 14 and 147 ± 9, respectively, p < 0.001). In addition, the P1 amplitude (uV) was enhanced in the MP group compared to the PBS group (55 ± 12 and 41 ± 13, respectively, p < 0.05). TUNEL assays showed a decrease in the number of apoptotic cells in the RGC layers of MP-treated retinas compared to the PBS-treated group (p < 0.05). ED1 positive cells (/HPF) were significantly decreased in the ONs of the MP group compared to the PBS group (p < 0.001). In conclusion, systemic administration of MP had neuroprotective effects on RGC survival and ON function in the rAION animal model.