Abstract
Purpose: :
We investigated the possible mitochondrial membrane permeability and potential in optic nerve and retinal ganglion cell (RGC) after intraocular pressure (IOP) elevation with rat glaucoma model.
Methods: :
Rat glaucoma model was carried out with argon laser photocoagulation after intracameral injection of india ink. Dark-phase IOP measurements were monitored with a portable tonometer (Tonolab). RGC isolation was performed with magnetic beads coated with Thy-1 monoclonal antibody. The levels of thioredoxin2 (Trx2) in RGC and optic nerve were examined with immunoblot analysis. At 5 weeks after IOP elevation, retrograde labeling to identify mitochondria was performed by placing a gelfoam soaked with MitoTracker Red CMXRos to the superior colliculus 1 week before the enucleation. The distribution of mitochondria was examined with fluorescence confocal microscope.
Results: :
Elevated IOP was sustained until 5 weeks after laser photocoagulation. Morphometric analysis showed a significant decrease in axon number in glaucomatous eyes. Immunoblot analysis showed a significant decreased mitochondrial Trx2 level, which regulates mitochondrial membrane permeability, in both RGC and optic nerve 5 weeks after IOP elevation. The distribution of dye-labeled mitochondria, which is regulated by mitochondria membrane potential, appeared to be decreased in the lamina cribrosa area 5 weeks after IOP elevation, compared with the contralateral control eye.
Conclusions: :
These findings provide the possibility that the decreases of mitochondrial membrane permeability and potential are involved in glaucomatous optic neuropathy.
Keywords: mitochondria • neuroprotection • optic nerve