Yokota Satoshi, Takihara Yuji, Arimura Shogo, Miyake Seiji, Takamura Yoshihiro, Yoshimura Nagahisa, Inatani Masaru
Department of Ophthalmology Faculty of Medical Science, University of Fukui, Fukui, Japan 2Department of Ophthalmology and Visual Sciences, Kyoto University Graduate School of Medicine, Kyoto, Japan.
Department of Ophthalmology Faculty of Medical Science, University of Fukui, Fukui, Japan.
Invest Ophthalmol Vis Sci. 2015 Dec;56(13):8019-25. doi: 10.1167/iovs.15-17876.
Axonal damage precedes retinal ganglion cell (RGC) apoptosis in glaucomatous optic neuropathy. Because mitochondria in RGC axons are damaged before cell death, we examined axonal mitochondrial transport dynamics after axonal injury.
Mitochondria in rat-cultivated RGCs were stained with rhodamine 123. After axonal injury induced using a laser microdissection system, axonal transport was evaluated by time-lapse imaging. The RGC apoptosis was detected using ethidium homodimer-1 on day 3 after axonal injury.
The rate of stationary mitochondria in RGC axons significantly increased from 37.6% before axonal injury to 70.6% at 5 minutes (P < 0.001) and 63.6% at 18 hours (P < 0.001) after axonal injury. The mean axonal mitochondrial transport velocity in RGCs transiently deteriorated from 0.48 ± 0.01 μm/s before axonal injury to 0.37 ± 0.02 μm/s at 5 minutes after axonal injury (P < 0.001). However, 23.5% of RGCs showed recovered axonal transport velocity at 18 hours after injury. On day 3 after axonal injury, RGCs with the recovery of axonal transport did not undergo apoptosis, whereas 69.2% of RGCs without the recovery of axonal transport underwent apoptosis (P = 0.029).
Axonal injury disrupts mitochondrial transport in RGC axons. Irreversible decreased axonal mitochondrial transport velocity may be useful to predict RGC apoptosis after axonal injury.
在青光眼性视神经病变中，轴突损伤先于视网膜神经节细胞（RGC）凋亡。由于RGC轴突中的线粒体在细胞死亡前就已受损，我们研究了轴突损伤后轴突线粒体运输动力学。
用罗丹明123对大鼠培养的RGC中的线粒体进行染色。使用激光显微切割系统诱导轴突损伤后，通过延时成像评估轴突运输。在轴突损伤后第3天，用乙锭同二聚体-1检测RGC凋亡。
RGC轴突中静止线粒体的比例从轴突损伤前的37.6%显著增加到损伤后5分钟时的70.6%（P<0.001）和18小时时的63.6%（P<0.001）。RGC中轴突线粒体的平均运输速度从轴突损伤前的0.48±0.01μm/s短暂下降到损伤后5分钟时的0.37±0.02μm/s（P<0.001）。然而，23.5%的RGC在损伤后18小时显示轴突运输速度恢复。轴突损伤后第3天，轴突运输恢复的RGC未发生凋亡，而轴突运输未恢复的RGC中有69.2%发生凋亡（P=0.029）。
轴突损伤会破坏RGC轴突中的线粒体运输。轴突线粒体运输速度不可逆降低可能有助于预测轴突损伤后RGC凋亡。
