Comparison of visual function in pigmented and albino rats by electroretinography and visual evoked potentials.
OBJECTIVE
To check differences in visual function between Wistar (albino) and Long-Evans (pigmented) rats.


METHODS
The animals were born in our facilities and reared under identical light conditions avoiding bright light. Visual electrophysiology was performed at the ages of 1.5, 4, 7 and 10 months (electroretinography, ERG) and at 1.5 and 7 months (visual evoked potentials, VEP).


RESULTS
ERG measurements showed that: 1) The amplitudes of both scotopic and photopic b-waves were markedly larger in Long-Evans rats than in Wistar rats, and also the amplitudes of scotopic oscillatory potentials and photopic 30 Hz Flicker amplitudes, 2) scotopic a-wave amplitudes were larger in Wistar rats at low light intensities, whereas they were smaller in bright light, 3) both a-wave and b-wave latencies were shorter in Wistar rats, 4) the maximum response Rm(P3) was larger in Long-Evans rats, 5) the sensitivity parameter S was larger in Wistar rats, and 6) the post-receptoral response of cones was smaller in Wistar rats. In the VEP measurements, amplitudes of both photopic and scotopic visual evoked potentials of Long-Evans rats were only slightly larger than those of Wistar rats.


CONCLUSIONS
ERG b-wave amplitudes are markedly decreased in Wistar rats, which requires further investigation. As the b/a and OP/a ratios were also decreased in Wistar rats, it can be suggested that post-receptoral processing, in particular, is impaired in albino animals.
Heiduschka
Peter
P
Section for Experimental Vitreoretinal Surgery, University Eye Hospital, Schleichstr. 12/1, D-72076, Tübingen, Germany. p.heiduschka@uni-tuebingen.de
Schraermeyer
Ulrich
U
D000221:Adaptation, Ocular; D000818:Animals; D003623:Dark Adaptation; D004596:Electroretinography / Q000379:methods; D005074:Evoked Potentials, Visual; D009991:Oscillometry; D010775:Photic Stimulation / Q000379:methods; D051381:Rats; D020318:Rats, Long-Evans / Q000502:physiology*; D017208:Rats, Wistar / Q000502:physiology*; D011930:Reaction Time; D017949:Retinal Cone Photoreceptor Cells / Q000502:physiology; D014785:Vision, Ocular