Abstract
Abstract: :
Purpose: Considering that certain eye–care products applied locally or systemically reach the back of the eye, a long–term exposure to these compounds could possibly affect retinal function as measured by electroretinography (ERG). The aim of this study is to characterize baseline ERG parameters in two pigmented and one albino strain of rabbits commonly used in pharmaceutical testing. Methods: ERGs were obtained from naïve New Zealand White (NZW), New Zealand White crossed with New Zealand Red (NZWxR, F1 progeny), and Dutch Belted (DB) rabbits (n=6/group, 3F+3M) that were tested at 6–weeks intervals between the ages of 12 and 87 weeks. Amplitudes and peak times of a–wave, rod Vmax, mixed b–wave and cone b–wave were collected. Results: At 12 weeks of age, amplitudes of all measured ERG parameters in all three strains of rabbits were significantly lower than subsequent readings. Amplitudes followed a trend of slow but steady increase over the next 40 weeks, reaching maximal values at 50–60 week of life when they reached the plateau or start to decline. Peak times were unchanged until 45 week and later increased for Rod Vmax and mixed b–wave. At 57 week a–wave and cone b–wave amplitudes of NZW and DB were not significantly different (64.6±18.7 vs. 76.8±15.4 µV for a–wave and 104.0±42.7 vs. 145.8±53.9 µV for cone b–wave) while those of NZWxR were significantly lower (32.8±20.6 for a–wave and 73.2±17.9 µV for cone b–wave). Analysis of rod–dominated responses revealed no significant difference between the amplitudes of NZW and NZWxR whereas the latter were significantly lower than DB (142.7±45.9 vs. 109.1±54.8 vs. 195.3±62.6 µV for Rod Vmax and 162.7±57.2 vs. 140.3±32.0 vs.235.1±78.1 µV for mixed b–wave). Conclusions: The two pigmented strains of rabbits yielded unexpectedly different results from one another, whereas some similarities were observed between them and the albino breed . When testing eye–care products potentially harmful to the retinal function, care has to be taken to choose the correct age and suitable breeds of albino and pigmented animals in order to account for maturation of retinal function and different pigment content.
Keywords: electroretinography: non–clinical