Susceptibility of retinal ganglion cells to excitotoxicity depends on soma size and retinal eccentricity.
OBJECTIVE
This study was undertaken to determine if retinal ganglion cell sensitivity to intraocular N-methyl-D-aspartate or kainate injections varied as a function of retinal location (eccentricity) or cell soma size.


METHODS
Rat retinal ganglion cells surviving intraocular N-methyl-D-aspartate or intraocular kainate induced lesions were retrogradely labeled with horseradish peroxidase and analyzed using an image analysis system. Control animals were retrogradely labeled after vehicle injection only. Cell counting was performed at 48 sampling points over the entire retina and represented a total area of 1.92 mm2 per retina.


RESULTS
Larger cells were more sensitive to kainate than to N-methyl-D-aspartate excitotoxicity; smaller cells more vulnerable to N-methyl-D-aspartate excitotoxicity. Further from the optic nerve, more smaller cells survived kainate administration. After N-methyl-D-aspartate administration, larger cells survived most, noticeably in the central retina.


CONCLUSIONS
Our results suggest that loss of retinal ganglion cells after N-methyl-D-aspartate or kainate administration affects distinct populations of retinal ganglion cells, dependent upon soma size and retinal location. The mechanism by which certain classes of cells survive or succumb to such insults has yet to be determined.
Vorwerk
C K
CK
Institute of Medical Psychology, Medical Faculty, Otto-von- Guerericke University, Magdeburg, FRG. ckvorwerk@aol.com
Kreutz
M R
MR
Böckers
T M
TM
Brosz
M
M
Dreyer
E B
EB
Sabel
B A
BA
D000818:Animals; D048429:Cell Size / Q000502:physiology; D002470:Cell Survival / Q000187:drug effects; D007608:Kainic Acid / Q000494:pharmacology; D008297:Male; D016202:N-Methylaspartate / Q000494:pharmacology; D009498:Neurotoxins / Q000494:pharmacology*; D051381:Rats; D011919:Rats, Inbred Strains; D012160:Retina / Q000166:cytology / Q000502:physiology*; D012165:Retinal Ganglion Cells / Q000166:cytology* / Q000187:drug effects* / Q000502:physiology
D009498:Neurotoxins; D016202:N-Methylaspartate; D007608:Kainic Acid