Abstract
Abstract: :
Purpose: To characterize ERG components generated by non-neuronal tissues of the rat eye. Methods: Adult rats of two strains (Long-Evans, LE; Sprague-Dawley, SD) were sedated with ketamine/xylazine and placed on a heating pad. Ag/AgCl electrodes were fashioned with capillary tubes filled with Hanks BSS. An electrode was placed in contact with the corneal surface and referenced to a second electrode placed within the orbit. The dc-ERG signal was amplified (dc-100 Hz), digitized and stored off-line. The presentation of full-field flash stimuli was controlled using a Uniblitz shutter. Flash intensity, controlled with neutral density filters, varied from 0.6 to 3.7 log cd/m2. EOGs were recorded using sub-dermal platinum needle electrodes placed near the eye. Results: In response to a 5 min light exposure, the rat dc-ERG included a distinct b-wave, after potential (AP), c-wave, fast oscillation (FO) and light peak (LP). In LE rats the final plateau of the LP was usually lower than the pre-stimulus baseline; in SD rats, the LP achieved a level above the baseline. The difference between the two rat strains was due to a difference in the amplitude of the AP, which was smaller in SD rats. EOGs recorded from these two strains yielded results consistent with the amplitude of the LP relative to the pre-stimulus baseline. Specifically, the amplitude of the EOG of SD rats increased when the eye was exposed to light. This increase did not occur, and was often negative, for LE rats. Conclusion: The major components of the dc-ERG are readily measured in the rat. Therefore, the rat may provide a useful animal model in which to conduct pharmacological analysis of non-neuronal responses and to develop animal models of human retinal disorders involving the RPE, such as Best macular dystrophy.
Keywords: 396 electroretinography: non-clinical • 394 electrophysiology: non-clinical