Center for Neuroscience Research (NeuRon), Faculty of Medicine, Universiti Teknologi MARA, Sungai Buloh Campus, Sungai Buloh, Selangor, Malaysia.
Center for Neuroscience Research (NeuRon), Faculty of Medicine, Universiti Teknologi MARA, Sungai Buloh Campus, Sungai Buloh, Selangor, Malaysia; Volgograd State Medical University, Research Institute of Pharmacology, Volgograd, Russia.
Neurotoxicology. 2019 Jan;70:62-71. doi: 10.1016/j.neuro.2018.10.009. Epub 2018 Oct 30.
N-methyl-D-aspartate (NMDA) excitotoxicity has been proposed to mediate apoptosis of retinal ganglion cells (RGCs) in glaucoma. Taurine (TAU) has been shown to have neuroprotective properties, thus we examined anti-apoptotic effect of TAU against retinal damage after NMDA exposure.
Sprague-Dawley rats were divided into 5 groups of 33 each. Group 1 was administered intravitreally with PBS and group 2 was similarly injected with NMDA (160 nmol). Groups 3, 4 and 5 were injected with TAU (320 nmol) 24 hours before (pre-treatment), in combination (co-treatment) and 24 hours after (post-treatment) NMDA exposure respectively. Seven days after injection, rats were sacrificed; eyes were enucleated, fixed and processed for morphometric analysis, TUNEL and caspase-3 staining. Optic nerve morphology assessment was done using toluidine blue staining. The estimation of BDNF, pro/anti-apoptotic factors (Bax/Bcl-2) and caspase-3 activity in retina was done using ELISA technique.
Severe degenerative changes were observed in retinae after intravitreal NMDA exposure. The retinal morphology in the TAU pre-treated group appeared more similar to the control retinae and demonstrated a higher number of nuclei than the NMDA group both per 100 μm length (by 1.5-fold, p < 0.001) and per 100 μm area (by 1.41-fold, p < 0.05) of the GCL. After NMDA exposure, visible axonal swelling was observed in optic nerve sections. In comparison with the changes observed in the NMDA treated group, the TAU treated group showed fewer prominent changes; axonal swelling was less frequent and less marked. Additionally, no marked glial cell changes were observed in the TAU-pretreated group. All TAU treated groups, particularly the pre-treated group, showed a significant decrease in the NMDA-induced optic nerve damage, with a 50% reduction (p < 0.001) in the mean grading compared to NMDA group. For the same, there was 25% decrease in co- and post-treatment groups, as compared with the NMDA group. Pre-treatment with TAU abolished apoptotic response to NMDA as indicated by decrease in the number of TUNEL- and caspase-3-positive cells. TAU pre-treatment also increased the Bcl-2 level (by 2.80-fold, p < 0.001) and decreased the level of Bax (by 34%, p < 0.01), and activity of caspase-3 (by 36%, p < 0.001) compared to NMDA group.
our study revealed that pre-treatment with TAU prevents NMDA-induced retinal cell apoptosis more effectively than co- and post-treatment with TAU.
N-甲基-D-天冬氨酸（NMDA）兴奋性毒性被认为介导了青光眼中原发性神经节细胞（RGCs）的凋亡。牛磺酸（TAU）已被证明具有神经保护作用，因此我们研究了 TAU 对 NMDA 暴露后视网膜损伤的抗凋亡作用。
SD 大鼠分为 5 组，每组 33 只。第 1 组玻璃体腔内注射 PBS，第 2 组玻璃体腔内注射 NMDA（160nmol）。第 3、4 和 5 组分别在 NMDA 暴露前 24 小时（预处理）、同时（联合处理）和 24 小时后（后处理）注射 TAU（320nmol）。注射后 7 天处死大鼠；眼球取出，固定并进行形态计量分析、TUNEL 和 caspase-3 染色。用甲苯胺蓝染色评估视神经形态。使用 ELISA 技术测定视网膜中 BDNF、促凋亡/抗凋亡因子（Bax/Bcl-2）和 caspase-3 活性。
玻璃体腔内 NMDA 暴露后，视网膜出现严重退行性改变。与 NMDA 组相比，TAU 预处理组的视网膜形态更类似于对照组，且每 100μm 长度（1.5 倍，p<0.001）和每 100μm 面积（1.41 倍，p<0.05）的 GCL 核数更多。NMDA 暴露后，视神经切片中可见轴突肿胀。与 NMDA 处理组观察到的变化相比，TAU 处理组的变化不明显；轴突肿胀不频繁且不明显。此外，在 TAU 预处理组中未观察到明显的胶质细胞变化。所有 TAU 处理组，特别是预处理组，NMDA 诱导的视神经损伤明显减少，与 NMDA 组相比，平均分级降低了 50%（p<0.001）。与 NMDA 组相比，联合处理组和后处理组分别降低了 25%。TAU 预处理可消除 NMDA 诱导的细胞凋亡反应，表现为 TUNEL 和 caspase-3 阳性细胞数量减少。TAU 预处理还增加了 Bcl-2 水平（2.80 倍，p<0.001），降低了 Bax 水平（34%，p<0.01）和 caspase-3 活性（36%，p<0.001），与 NMDA 组相比。
本研究表明，与联合和后处理相比，TAU 预处理更有效地预防 NMDA 诱导的视网膜细胞凋亡。
