Oxidative stress is an early event in hydrostatic pressure induced retinal ganglion cell damage.
OBJECTIVE
To determine whether oxidative adduct formation or heme oxygenase-1 (HO-1) expression are altered in retinal ganglion cell (RGC) cultures exposed to elevated hydrostatic pressure and in a mouse model of glaucoma.


METHODS
Cultured RGC-5 cells were subjected to 0, 30, 60, or 100 mm Hg hydrostatic pressure for 2 hours, and the cells were harvested. Parallel experiments examined the recovery from this stress, the effect of direct 4-hydroxy-2-nonenal (HNE) treatment, and the effect of pretreatment with resveratrol or quercetin. Mice were anesthetized and intraocular pressure was increased to 30, 60, or 100 mm Hg for 1 hour; then the retinas were harvested. HNE adduct formation and HO-1 expression were assessed by immunocytochemistry and immunoblotting.


RESULTS
Increases of HNE-protein adducts (up to 5-fold) and HO-1 expression (up to 2.5 fold) in pressure-treated RGC-5 cells were dose dependent. During recovery experiments, HNE-protein adducts continued to increase for up to 10 hours; in contrast, HO-1 expression decreased immediately. HNE, at a concentration as low as 5 muM, led to neurotoxicity in RGC-5 cells. HNE adducts and HO-1 expression increased in the mouse retina and optic nerve after acute IOP elevation up to 5.5-fold and 2-fold, respectively. Antioxidant treatment reduced the oxidative stress level in pressure-treated RGC-5 cells.


CONCLUSIONS
This study demonstrates that oxidative stress is an early event in hydrostatic pressure/IOP-induced neuronal damage. These findings support the view that oxidative damage contributes early to glaucomatous optic neuropathy.
Liu
Quan
Q
Hamilton Glaucoma Center and the Department of Ophthalmology, University of California San Diego, La Jolla, California 92037-0946, USA.
Ju
Won-Kyu
WK
Crowston
Jonathan G
JG
Xie
Fang
F
Perry
George
G
Smith
Mark A
MA
Lindsey
James D
JD
Weinreb
Robert N
RN
D000447:Aldehydes / Q000494:pharmacology; D000818:Animals; D017209:Apoptosis; D015153:Blotting, Western; D002461:Cell Line, Transformed; D002470:Cell Survival; D002478:Cells, Cultured; D004195:Disease Models, Animal; D005452:Fluoresceins / Q000378:metabolism; D019084:Fluorescent Antibody Technique, Indirect; D005901:Glaucoma / Q000209:etiology* / Q000378:metabolism / Q000473:pathology; D051547:Heme Oxygenase-1 / Q000378:metabolism; D006874:Hydrostatic Pressure / Q000009:adverse effects*; D007429:Intraocular Pressure; D051379:Mice; D008810:Mice, Inbred C57BL; D008856:Microscopy, Fluorescence; D009687:Nuclear Proteins; D009901:Optic Nerve Diseases / Q000209:etiology* / Q000378:metabolism / Q000473:pathology; D018384:Oxidative Stress; D051381:Rats; D012164:Retinal Diseases / Q000209:etiology* / Q000378:metabolism / Q000473:pathology; D012165:Retinal Ganglion Cells / Q000187:drug effects / Q000378:metabolism / Q000473:pathology*
D000447:Aldehydes; D005452:Fluoresceins; D009687:Nuclear Proteins; C085925:calcein AM; D051547:Heme Oxygenase-1; C027576:4-hydroxy-2-nonenal