Department of Pharmaceutical Sciences, Northeast Ohio Medical University, Rootstown, Ohio, United States.
Invest Ophthalmol Vis Sci. 2019 Jan 2;60(1):1-15. doi: 10.1167/iovs.18-24977.
Reoxygenation after hypoxia can increase reactive oxygen species and upregulate autophagy. We determined, for the first time, the impact of elevated IOP on hypoxia induction, superoxide accumulation, and autophagy in a bead model of glaucoma.
Ocular hypertension was achieved with magnetic bead injection into the anterior chamber. Before mice were killed, they were injected with pimonidazole for hypoxia detection and dihydroethidium (DHE) for superoxide detection. Total retinal ganglion cells (RGCs) and optic nerve (ON) axons were quantified, total glutathione (GSH) was measured, and retinal and ON protein and mRNA were analyzed for hypoxia (Hif-1α and Hif-2α), autophagy (LC3 and p62), and SOD2.
With IOP elevation (P < 0.0001), the retina showed significantly (P < 0.001) decreased GSH compared with control, and a significant decrease (P < 0.01) in RGC density compared with control. Pimonidazole-positive Müller glia, microglia, astrocytes, and RGCs were present in the retinas after 4 weeks of ocular hypertension but absent in both the control and after only 2 weeks of ocular hypertension. The ON showed significant axon degeneration (P < 0.0001). The mean intensity of DHE in the ganglion cell layer and ON significantly increased (P < 0.0001). The ratio of LC3-II to LC3-I revealed a significant increase (P < 0.05) in autophagic activity in hypertensive retinas compared with control.
We report a novel observation of hypoxia and a significant decrease in GSH, likely contributing to superoxide accumulation, in the retinas of ocular hypertensive mice. The significant increase in the ratio of LC3-II to LC3-I suggests autophagy induction.
缺氧后再复氧会增加活性氧物种并上调自噬。我们首次确定了升高的眼内压（IOP）对珠模型中青光眼缺氧诱导、超氧积累和自噬的影响。
通过在前房内注射磁性珠来实现眼高压。在处死小鼠之前，它们被注射了 pimonidazole 以检测缺氧，和二氢乙啶（DHE）以检测超氧。定量了总视网膜神经节细胞（RGC）和视神经（ON）轴突，测量了总谷胱甘肽（GSH），并分析了视网膜和 ON 的蛋白质和 mRNA，以检测缺氧（Hif-1α 和 Hif-2α）、自噬（LC3 和 p62）和 SOD2。
随着 IOP 升高（P < 0.0001），与对照组相比，视网膜的 GSH 显著（P < 0.001）降低，与对照组相比，RGC 密度显著（P < 0.01）降低。在 4 周眼高压后，Müller 胶质细胞、小胶质细胞、星形胶质细胞和 RGC 中出现了 pimonidazole 阳性，但在对照组和仅 2 周眼高压后均未出现。ON 显示出明显的轴突退化（P < 0.0001）。节细胞层和 ON 中的 DHE 平均强度显著增加（P < 0.0001）。与对照组相比，高血压视网膜中 LC3-II 与 LC3-I 的比值显著增加（P < 0.05），表明自噬活性增加。
我们报告了一个新的观察结果，即在眼高压小鼠的视网膜中存在缺氧和 GSH 的显著减少，这可能导致超氧积累。LC3-II 与 LC3-I 的比值显著增加表明自噬诱导。
