Up-regulation of cytochrome oxidase in the retina following optic nerve injury.
The purpose of this study is to investigate the cytochrome oxidase (COX) activity in the retina and optic nerve following an optic nerve injury. The optic nerve crush of one eye was carried out in Balb/c mice. A semi-quantitative RT-PCR method was then adopted to evaluate the mRNA expression of cytochrome oxidase subunit 1 (COX1) in the retina after surgery. Up-regulation of COX1 mRNA in the retina was detected by RT-PCR at 24 hr following the optic nerve injury. Total retinal mitochondrial mass measured by fluorescent intensity of MitoTracker green was not altered following the injury. COX histochemistry performed on cryostat sections showed an elevated enzyme activity of COX in the retina and in the optic nerve. In the retina, elevation of the COX activity was observed in the retinal ganglion cell layer and the overlying nerve fibre layer. The increase of COX activity began from 24 hr after injury, peaked around day 3, and maintained up to 1 week after the operation. In the optic nerve, increase of COX activity was observed in regions distal to the crush line and distributed either randomly or in a cone shape. In conclusion, both the expression of COX1 mRNA in retina and the activity of COX in inner plexiform layer and retinal ganglion cell layer were elevated following optic nerve injury without affecting total retinal mitochondrial mass. These findings suggested that one of early responses in the retina and in the optic nerve after the optic nerve injury is to scale up the energy production.
Wang
An-Guor
AG
Department of Ophthalmology, Taipei Veterans General Hospital, Taipei, Taiwan, Republic of China.
Lee
Chia-Ming
CM
Wang
Yu-Chuan
YC
Lin
Chi-Hung
CH
Fann
Ming-Ji
MJ
D000818:Animals; D051545:Cyclooxygenase 1; D003576:Electron Transport Complex IV / Q000235:genetics / Q000378:metabolism*; D007091:Image Processing, Computer-Assisted / Q000379:methods; D007527:Isoenzymes; D008565:Membrane Proteins; D051379:Mice; D008807:Mice, Inbred BALB C; D009416:Nerve Regeneration / Q000502:physiology; D020221:Optic Nerve Injuries / Q000201:enzymology* / Q000235:genetics; D011451:Prostaglandin-Endoperoxide Synthases; D012333:RNA, Messenger / Q000235:genetics; D012160:Retina / Q000201:enzymology*; D012165:Retinal Ganglion Cells / Q000201:enzymology; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015854:Up-Regulation
D007527:Isoenzymes; D008565:Membrane Proteins; D012333:RNA, Messenger; D051545:Cyclooxygenase 1; D011451:Prostaglandin-Endoperoxide Synthases; C496512:Ptgs1 protein, mouse; D003576:Electron Transport Complex IV