Assessment of glutamate loss from the ganglion cell layer of young DBA/2J mice with glaucoma.
OBJECTIVE
To determine whether glutamate contents are decreased in the ganglion cell layer (GCL) of retinas of DBA/2J mice with glaucoma, compared with unaffected control mice.


METHODS
20 eyes from DBA/2J mice (9-week-old mice [n = 8] and 4- [4], 6- [4], and 12-month-old [4] mice) and 17 eyes from control CD-1 (7) and C57/BL6 (10) mice of similar age.


METHODS
After euthanasia, the eyes were rapidly dissected and fixed. Serial 0.5-microm sections were prepared from eyecups and stained with toluidine blue (to identify damaged cells) or immunogold (to localize glutamate). Microscopic images were captured digitally for comparison; immunostaining densities were assessed via special software.


RESULTS
In the GCL of control mice, few cells appeared damaged; large amounts of glutamate were detected in 83 +/- 8.3% of cells. In DBA/2J mice > or = 9 weeks of age, damaged neurons were observed in retinal sections; the level of glutamate immunoreactivity was high in a few cells near areas of damage (13 +/- 3.2%) and in many cells in less-damaged regions of the same sections (82 +/- 4.2%). Many neurons with low amounts of glutamate in damaged regions did not appear damaged histologically.


CONCLUSIONS
In retinas of young DBA/2J mice, damaged and undamaged GCL cells had decreased levels of immunostaining for glutamate, compared with less-damaged adjacent regions or retinas from control mice. The loss of neuronal glutamate in damaged retinal regions suggests that glutamate is contributing to early retinal damage prior to changes in intraocular pressure.
Low
Heather C
HC
Department of Clinical Sciences, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, CO 80523, USA.
Gionfriddo
Juliet R
JR
Madl
James E
JE
D000375:Aging; D000818:Animals; D005901:Glaucoma / Q000378:metabolism*; D018698:Glutamic Acid / Q000378:metabolism*; D051379:Mice; D008810:Mice, Inbred C57BL; D008811:Mice, Inbred DBA; D012165:Retinal Ganglion Cells / Q000378:metabolism*
D018698:Glutamic Acid