Li Tingting, Kowal Tia J, Zhao Jingyu, Li Liang, Wang Qing, Ning Ke, Lo Chien-Hui, Liu Zhiquan, Shen Yingchun, Yu Jing, Jin Haiying, Sun Yang
Department of Ophthalmology, Shanghai East Hospital, Tongji University School of Medicine, Shanghai, 200120, China; Department of Ophthalmology, Stanford University School of Medicine, Palo Alto, CA, 94306, USA.
Department of Ophthalmology, Stanford University School of Medicine, Palo Alto, CA, 94306, USA.
Exp Eye Res. 2025 Jun;255:110355. doi: 10.1016/j.exer.2025.110355. Epub 2025 Mar 22.
Brimonidine has shown neuroprotective effects in animal studies, but clinical trials failed to demonstrate effective endpoints. Here, we used a newly developed in vivo calcium imaging method to measure RGC function of brimonidine in mice optic nerve crush (ONC) models. To transduce RGCs in vivo, wild-type C57Bl/6j mice were treated with intravitreal AAV2-mSncg-jGCaMP7s, a live-cell Ca tracer. RGCs are defined as 10 subtypes according to different responses to UV light. Mice were treated with topical brimonidine or placebo three times daily for two weeks after ONC. The calcium signals of live-cell RGCs were measured with the Heidelberg cSLO system. Ganglion cell complex (GCC) thickness and IOP were examined at different timepoints after treatment. RGCs were counted after RBPMS immunostaining. Live calcium imaging showed ONC significantly decreased RGC number at 14 days post-ONC compared to controls. The topical brimonidine administration changed calcium signal responses of RGC to UV light in ONC mice. It showed brimonidine partly prevented the decrease of survival ON-RGCs percent after ONC. Single RGC analysis showed a lower conversion percent of ON-RGCs to OFF-RGCs with brimonidine administration after ONC. However, no significant differences in RGC survival, IOP or GCC thickness were noted between eyes treated with brimonidine or placebo. In the acute ONC mice model, in vivo calcium imaging revealed that brimonidine maintained the Ca activation of ON-RGCs to UV stimulation, inhibiting the conversion of survival ON-RGCs to OFF-RGCs. This indicates that ON-RGCs may be more resilient to acute optic nerve injury based on the calcium imaging method.
溴莫尼定在动物研究中已显示出神经保护作用，但临床试验未能证明有效终点。在此，我们使用一种新开发的体内钙成像方法来测量溴莫尼定在小鼠视神经挤压（ONC）模型中的视网膜神经节细胞（RGC）功能。为了在体内转导RGC，野生型C57Bl/6j小鼠接受玻璃体内注射AAV2-mSncg-jGCaMP7s（一种活细胞钙示踪剂）治疗。RGC根据对紫外线的不同反应被定义为10种亚型。ONC后，小鼠每天接受三次局部溴莫尼定或安慰剂治疗，持续两周。使用海德堡cSLO系统测量活细胞RGC的钙信号。在治疗后的不同时间点检查神经节细胞复合体（GCC）厚度和眼压。RBPMS免疫染色后对RGC进行计数。实时钙成像显示，与对照组相比，ONC后14天RGC数量显著减少。局部给予溴莫尼定改变了ONC小鼠中RGC对紫外线的钙信号反应。结果表明，溴莫尼定部分预防了ONC后存活的ON-RGC百分比的下降。单个RGC分析显示，ONC后给予溴莫尼定，ON-RGC向OFF-RGC的转化率较低。然而，接受溴莫尼定或安慰剂治疗的眼睛在RGC存活、眼压或GCC厚度方面没有显著差异。在急性ONC小鼠模型中，体内钙成像显示溴莫尼定维持了ON-RGC对紫外线刺激的钙激活，抑制了存活的ON-RGC向OFF-RGC的转化。这表明基于钙成像方法，ON-RGC可能对急性视神经损伤更具弹性。
