Neuron stress and loss following rodent anterior ischemic optic neuropathy in double-reporter transgenic mice.
OBJECTIVE
Nonarteritic anterior ischemic optic neuropathy (NAION) is an optic nerve infarct involving axons of retinal ganglion cell (RGC) neurons. The rodent NAION model (rAION) can use transgenic mouse strains to reveal unique characteristics about the effects of sudden optic nerve ischemia on RGCs and their axons. The impact of rAION on RGC stress patterns, RGC loss, and their axons after axonal infarct were evaluated.


METHODS
A double-transgenic mouse strain was used, containing a construct with cyan fluorescent protein (CFP) under Thy-1 promoter control, and a construct with beta-galactosidase (lacZ) linked to the stress gene c-fos promoter. Thy-1 in the retina is expressed predominantly in RGCs, enabling stereologic analysis of CFP(+) RGC numbers and loss post-rAION-using confocal microscopy. RGC loss was correlated with axonal counts using transmission electron microscopy (TEM). LacZ immunohistochemistry was used to evaluate retinal cell stress after rAION.


RESULTS
The 45,000 CFP(+) cells in the RGC layer of control animals compared with previous RGC quantitative estimates. rAION produced RGC stress, defined as lacZ expression, in patterns corresponding with later RGC loss. rAION-associated RGC loss correlated with regional nerve fiber layer loss. Axonal loss correlates with stereologically determined RGC loss estimates in transgenic mice retinas.


CONCLUSIONS
Post-ON infarct RGC stress patterns correlate with regional RGC loss. Cellular lacZ levels in most RGCs are low, suggesting rAION-affected RGCs express c-fos only transiently. CFP(+) cell loss correlates closely with quantitative axonal loss, suggesting that the Thy-1 (CFP) transgenic mouse strain is appropriate for RGC stereologic analyses.
Bernstein
Steven L
SL
Departments of Ophthalmology, University of Maryland at Baltimore, School of Medicine, Baltimore, Maryland, USA. slbernst@umaryland.edu
Guo
Yan
Y
Slater
Bernard J
BJ
Puche
Adam
A
Kelman
Shalom E
SE
D000818:Animals; D001369:Axons / Q000378:metabolism / Q000473:pathology; D002452:Cell Count; D016923:Cell Death; D004195:Disease Models, Animal; D005456:Fluorescent Dyes / Q000378:metabolism; D016762:Genes, fos / Q000235:genetics; D049452:Green Fluorescent Proteins / Q000378:metabolism; D007150:Immunohistochemistry; D007238:Infarction / Q000473:pathology; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D018613:Microscopy, Confocal; D009474:Neurons / Q000378:metabolism / Q000473:pathology*; D009900:Optic Nerve / Q000098:blood supply; D018917:Optic Neuropathy, Ischemic / Q000378:metabolism / Q000473:pathology*; D012165:Retinal Ganglion Cells / Q000378:metabolism / Q000473:pathology*; D018800:Thy-1 Antigens / Q000235:genetics; D019076:Transgenes; D001616:beta-Galactosidase / Q000378:metabolism
C485182:Cyan Fluorescent Protein; D005456:Fluorescent Dyes; D018800:Thy-1 Antigens; D049452:Green Fluorescent Proteins; D001616:beta-Galactosidase