Pigmented Long-Evans rats demonstrate better visual ability than albino Wistar rats in slow angles-descent forepaw grasping test

Abstract

Albino people are known to have vision deficit. Albino animals are shown to have abnormal connectivity and malformation of the visual system. However, not many studies have revealed visual impairment of albino animals in the level of perception. To link anatomical abnormality and perceptual visual impairment of albinism, we compared the perceptual vision between the pigmented Long-Evans and the albino Wistar rats. We used the slow angled-descent forepaw grasping (SLAG) test. We hanged the rats in the air by their tails and slowly moved them around a safety bar so that they could see it. When the rats recognized the bar and try to grab it to escape, we counted the trial as ‘positive’, and we measured positive rates. We also measured the distance between the bar and their whiskers during the rats’ initial grasping action, and evaluated type of action at the first contact to the bar. The positive-action rate in the Long-Evans rat group showed significantly higher than the Wistar rat group (0.85 ± 0.047, n = 10, vs. 0.29 ± 0.043, n = 10; P < 0.0001). Besides, when the action was positive, the distance between the bar and their whiskers was longer in the Long-Evans rat group than that in the Wistar rat group (117 ± 5.3 mm vs. 58.8 ± 4.6 mm; P < 0.0001). The Long-Evans rats grasped the bar more precisely than the Wistar rats. The pigmented Long-Evans rats have much better visual perception than the albino Wistar rats.