In an ex vivo rat glaucoma model using dissected retinas, the neurosteroid allopregnanolone (AlloP) protects retinal ganglion cells (RGCs) via GABR/GABAA receptors. To determine the involvement of macroautophagy/autophagy in neuroprotection by AlloP, we examined the effects of autophagy activators, rapamycin and torin 2, and autophagy inhibitors, bafilomycin A1 and SAR405, on retinal retinal morphology and expression of MAP1 LC3B/LC3B (microtubule-associated protein 1 light chain 3 beta) and SQSTM1 (sequestosome 1). Administration of rapamycin or torin 2 exerted partial histological neuroprotection, while combined administration of AlloP with bafilomycin A1 or SAR405 induced severe degeneration in a hyperbaric condition. Electron microscopic analyses showed that the addition of AlloP significantly increased autophagosomes and degenerative autophagic vacuoles in the retinal nerve fiber layer. Immunoblotting showed that the addition of AlloP or autophagic activators increased the lipidated form of LC3B (LC3B-II) and suppressed SQSTM1. Moreover, bafilomycin A1 increased LC3B-II and SQSTM1 protein levels in the presence of AlloP without changes in corresponding mRNAs compared to AlloP-treated retinas in a hyperbaric condition. These data indicate that AlloP likely induces a protective form of autophagy in this model. In an in vivo rat model of glaucoma, we also observed neuroprotective effects of AlloP. Injection of polystyrene microbeads into the anterior chamber increased intraocular pressure about 3-fold and induced RGC apoptosis. A single intravitreal injection of AlloP or autophagy activators prevented apoptosis and protected RGCs with autophagy activation. We conclude that AlloP may serve as a potential therapeutic agent for the treatment of glaucoma via diverse mechanisms.Abbreviations: 2HBCD: 2-Hydroxypropyl)-β-cyclodextrin; 3-MA: 3-methyladenine; AlloP: allopregnanolone; AP: autophagosome; AVd: degradative autophagic vacuoles; GCL: ganglion cell layer; INL: inner nuclear layer; IOP: intraocular pressure; IPL: inner plexiform layer; LC3B-I: cytosolic form of LC3B; LCB-II: lipidated form of LC3B; MAP1LC3B/LC3B: microtubule-associated protein 1 light chain 3 beta; mPTP: mitochondrial permeability transition pore; NDS: neuronal damage score; NFL: nerve fiber layer; OH: ocular hypertension; ON: optic nerve; ONL: outer nuclear layer; OPL: outer plexiform layer; p-STR: scotopic threshold response; RGC: retinal ganglion cells; RT-PCR: real-time reverse transcription polymerase chain reaction; SQSTM1: sequestosome 1; TUNEL: TdT-mediated dUTP Nick End Labeling.

中文翻译：

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神经类固醇四氢孕酮通过影响大鼠青光眼模型中的自噬和 GABRs/GABAA 受体来保护视网膜神经元。


在使用解剖视网膜的离体大鼠青光眼模型中，神经类固醇四氢孕酮 (AlloP) 通过 GABR/GABAA 受体保护视网膜神经节细胞 (RGC)。为了确定巨自噬/自噬在 AlloP 神经保护中的作用，我们检查了自噬激活剂雷帕霉素和 torin 2 以及自噬抑制剂巴弗洛霉素 A1 和 SAR405 对视网膜形态和 MAP1 LC3B/LC3B（微管相关蛋白）表达的影响。蛋白 1 轻链 3 beta) 和 SQSTM1 (sequestosome 1)。雷帕霉素或torin 2的施用发挥了部分组织学神经保护作用，而AlloP与巴弗洛霉素A1或SAR405的联合施用在高压条件下诱导了严重的变性。电镜分析显示，AlloP的添加显着增加了视网膜神经纤维层中的自噬体和退行性自噬空泡。免疫印迹显示，添加 AlloP 或自噬激活剂可增加 LC3B (LC3B-II) 的脂化形式并抑制 SQSTM1。此外，与高压条件下 AlloP 处理的视网膜相比，在 AlloP 存在的情况下，巴弗洛霉素 A1 增加了 LC3B-II 和 SQSTM1 蛋白水平，而相应的 mRNA 没有变化。这些数据表明 AlloP 可能在此模型中诱导保护性的自噬形式。在青光眼大鼠体内模型中，我们还观察到 AlloP 的神经保护作用。将聚苯乙烯微珠注射到前房中可使眼压增加约3倍并诱导RGC凋亡。玻璃体内单次注射 AlloP 或自噬激活剂可防止细胞凋亡，并通过自噬激活保护 RGC。 我们得出结论，AlloP 可能通过多种机制作为治疗青光眼的潜在治疗剂。缩写：2HBCD：2-羟丙基)-β-环糊精； 3-MA：3-甲基腺嘌呤； AlloP：别孕酮； AP：自噬体； AVd：降解自噬泡； GCL：神经节细胞层； INL：内核层； IOP：眼压； IPL：内丛状层； LC3B-I：LC3B的胞质形式； LCB-II：LC3B 的脂化形式； MAP1LC3B/LC3B：微管相关蛋白1轻链3β； mPTP：线粒体通透性转换孔； NDS：神经元损伤评分； NFL：神经纤维层； OH：高眼压症； ON：视神经； ONL：外核层； OPL：外丛状层； p-STR：暗视阈值反应； RGC：视网膜神经节细胞； RT-PCR：实时逆转录聚合酶链式反应； SQSTM1: 隔离体 1; TUNEL：TdT 介导的 dUTP 缺口末端标记。