Sensory Capacity of the Royal College of Surgeons Rat

PURPOSE. To apply noninvasive tests for examining visual and other sensory functions of pigmented Royal College of Surgeons (RCS) rats compared with pigmented and albino control animals.METHODS. Rats aged 3 and 7 months were tested with a general neurologic examination that assessed visual, auditory, tactile, and whisker displacement responses. Photophobic responses and visual discrimination were also measured.RESULTS. Dystrophic RCS rats failed the visual presentation tests, even at 3 months of age, and showed diminished performance on tactile tests. Auditory and whisker displacement performances were normal. Albino rats also showed diminished performance on the visual test, particularly to stimuli presented in the upper visual field. Photophobic responses were diminished in the dystrophic RCS rats compared with the pigmented control animals. Albino animals showed heightened photophobia. The dystrophic rats failed to reach criterion levels of performance on the visual discrimination test even with gratings of 0.045 cyc/deg.CONCLUSIONS. The tests used discriminate deteriorated complex visual functions in RCS rats at ages when some simple reflexes can still be demonstrated. As such, they provide easily executed tests for screening for the effects of reparative treatments such as transplantation, administration of growth factors, and gene transfer technology. The integrity of whisker and auditory function are important when using tests requiring polysensory inputs. The somatosensory defect is surprising but may be useful in searching for the gene locus of the retinal disorder. The aberrations seen in the albino rats may be attributable to the effects of light damage and unfiltered light.