Ganglion cell responses to retinal light stimulation in the absence of photoreceptor outer segments from retinal degenerate rodents.
OBJECTIVE
To determine whether a severely degenerated retina without photoreceptor outer segments and a non-recordable electroretinogram (ERG) can still show retinal ganglion cell (RGC) responses to retinal light stimulation.


METHODS
The authors measured ERGs and retinal surface RGC responses from six week old rd mice and three month old homozygous S334ter line3 rats. Animal eyes were also studied by light microscopy, transmission electron microscopy, and immunohistochemistry (rats).


RESULTS
The corneal ERGs were non-recordable and no photoreceptor outer segments were found in either retinal degeneration model. A few cell bodies (without outer segments) that were immunoreactive for cone opsin and rhodopsin were found in the outer nuclear layer of the rats. Light-driven ON-RGC responses, however, were recordable from six week old rd mice. In addition, light-driven ON and OFF-RGC responses were recordable from three month old homozygous S334ter line 3 rats.


CONCLUSIONS
This study suggests that despite the apparent absence of photoreceptor outer segments and a non-recordable ERG, ganglion cell responses to retinal light stimulation may remain preserved in some severe retinal degenerate transgenic rodents.
Wilmer Ophthalmological Institute, Johns Hopkins University School of Medicine, Baltimore, Maryland 21287, USA.
Gi-Jung
GJ
An
Nobuya
N
Asayama
Mark S
MS
Humayun
James
J
Weiland
Jingtai
J
Cao
Shang-Yeon
SY
Kim
Rhonda
R
Grebe
Eugene
E
de Juan
Srinivas
S
Sadda
D000818:Animals; D000831:Animals, Newborn; D004596:Electroretinography; D007124:Immunoenzyme Techniques; D051379:Mice; D008809:Mice, Inbred C3H; D008810:Mice, Inbred C57BL; D010775:Photic Stimulation; D051381:Rats; D017207:Rats, Sprague-Dawley; D012160:Retina / Q000528:radiation effects*; D012162:Retinal Degeneration / Q000473:pathology / Q000503:physiopathology*; D012165:Retinal Ganglion Cells / Q000502:physiology* / Q000528:radiation effects; D012374:Rod Cell Outer Segment / Q000473:pathology*