Department of Biology, University of Pisa, Pisa, Italy.
Department for Innovation in Biological, Agro-Food and Forest Systems (DIBAF), University of Tuscia, Viterbo, Italy.
Pharmacol Res. 2018 Feb;128:167-178. doi: 10.1016/j.phrs.2017.09.022. Epub 2017 Sep 29.
Neuronal injury plays a major role in diabetic retinopathy (DR). Our hypothesis was that the balance between neuronal death and survival may depend on a similar equilibrium between apoptosis and autophagy and that a neuroprotectant may act by influencing this equilibrium. Ex vivo mouse retinal explants were treated with high glucose (HG) for 10days and the somatostatin analog octreotide (OCT) was used as a neuroprotectant. Chloroquine (CQ) was used as an autophagy inhibitor. Apoptotic and autophagic markers were evaluated using western blot and immunohistochemistry. HG-treated explants displayed a significant increase of apoptosis paralleled by a significant decrease of the autophagic flux, which was likely to be due to increased activity of the autophagy regulator mTOR (mammalian target of rapamycin). Treatment with OCT rescued HG-treated retinal explants from apoptosis and determined an increase of autophagic activity with concomitant mTOR inhibition. Blocking the autophagic flux with CQ completely abolished the anti-apoptotic effect of OCT. Immunohistochemical observations showed that OCT-induced autophagy is localized to populations of bipolar and amacrine cells and to ganglion cells. These observations revealed the antithetic role of apoptosis and autophagy, highlighting their equilibrium from which neuronal survival is likely to depend. These data suggest the crucial role covered by autophagy, which could be considered as a molecular target for DR neuroprotective treatment strategies.
神经元损伤在糖尿病性视网膜病变（DR）中起着重要作用。我们的假设是，神经元死亡和存活之间的平衡可能取决于细胞凋亡和自噬之间的类似平衡，而神经保护剂可能通过影响这种平衡发挥作用。用高葡萄糖（HG）处理离体鼠视网膜外植体 10 天，并将生长抑素类似物奥曲肽（OCT）用作神经保护剂。用氯喹（CQ）作为自噬抑制剂。使用 Western blot 和免疫组织化学评估细胞凋亡和自噬标记物。HG 处理的外植体显示细胞凋亡显著增加，同时自噬通量显著降低，这可能是由于自噬调节剂 mTOR（雷帕霉素的哺乳动物靶标）的活性增加所致。用 OCT 处理可使 HG 处理的视网膜外植体免于细胞凋亡，并确定自噬活性增加，同时 mTOR 抑制。用 CQ 阻断自噬通量可完全消除 OCT 的抗细胞凋亡作用。免疫组织化学观察显示，OCT 诱导的自噬定位于双极细胞和无长突细胞以及节细胞。这些观察结果揭示了细胞凋亡和自噬的拮抗作用，突出了它们的平衡，神经元的存活可能依赖于这种平衡。这些数据表明自噬所起的关键作用，自噬可能被认为是 DR 神经保护治疗策略的分子靶点。
