INRA, UMR1324 CSGA, Eye and Nutrition Research Group, Dijon, France.
Acta Ophthalmol. 2012 Nov;90(7):e560-7. doi: 10.1111/j.1755-3768.2012.02490.x. Epub 2012 Sep 23.
Our previous studies suggested that CYP46A1 and 24S-hydroxycholesterol (24SOH) may be associated with glaucoma. Loss of CYP46A1-expressing retinal ganglion cells is involved in the activation of glia, and therefore possibly in the disbalance of cholesterol. In this context, the purpose of our present work was to emphasize the glial and longitudinal CYP46A1 expression after an interventional glaucoma-related stress triggered by elevated intraocular pressure (IOP).
Sprague-Dawley rats were submitted to laser photocoagulation of the trabecular meshwork, limbus and episcleral veins in one eye to induce elevated IOP. Rats were euthanized at days 3, 14, 30 and 60 (n = 10 per time-point), and 24SOH was measured in plasma and retina by gas chromatography-mass spectrometry. CYP46A1 was quantified by Western blotting. Glial activation was assessed by glial fibrillary acidic protein immunoreactivity in Western blots and retinal cryosections.
Sustained high IOP was observed in experimental eyes from day 1 to day 21. Plasma MCP-1 and ICAM-1, quantified using multiplex assay kits, were increased at day 3. Glial activation was observed bilaterally at all time-points, at lower levels in contralateral eyes than in experimental eyes. In experimental retinas, CYP46A1 expression showed a transient increase at day 3 and then returned to baseline. Plasma and retinal 24SOH peaked at day 14 and 30, respectively.
These data show that CYP46A1 expression was induced early in response to retinal stress but remained constant at late time-points, reinforcing the constitutive role of CYP46A1 in maintaining cholesterol balance in neuronal tissues.
我们之前的研究表明 CYP46A1 和 24S-羟基胆固醇（24SOH）可能与青光眼有关。CYP46A1 表达的视网膜神经节细胞的丧失与神经胶质细胞的激活有关，因此可能与胆固醇的失衡有关。在这种情况下，我们目前工作的目的是强调在眼内压（IOP）升高引起与干预性青光眼相关的应激后，神经胶质细胞和纵向 CYP46A1 的表达。
Sprague-Dawley 大鼠一只眼的小梁网、角膜缘和巩膜静脉进行激光光凝，以诱导 IOP 升高。大鼠在第 3、14、30 和 60 天（每个时间点 n = 10）处死，通过气相色谱-质谱法测量血浆和视网膜中的 24SOH。通过 Western 印迹法定量 CYP46A1。通过 Western 印迹和视网膜冷冻切片中的胶质纤维酸性蛋白免疫反应性评估神经胶质细胞的激活。
从第 1 天到第 21 天，实验眼的持续高 IOP 被观察到。使用多重分析试剂盒测量的血浆 MCP-1 和 ICAM-1 在第 3 天增加。在所有时间点都观察到双侧神经胶质细胞激活，在对侧眼的水平低于实验眼。在实验性视网膜中，CYP46A1 表达在第 3 天短暂增加，然后恢复到基线。血浆和视网膜 24SOH 分别在第 14 天和第 30 天达到峰值。
这些数据表明，CYP46A1 表达在视网膜应激后早期被诱导，但在晚期保持不变，这加强了 CYP46A1 在维持神经元组织胆固醇平衡中的组成性作用。
