Purpose: To describe a possible spontaneous rat model of X-linked congenital stationary night blindness (CSNB).
Methods: Experimental animals were generated by mating the affected animal to normal rats, and from interbreeding littermates. To define the inheritance pattern, full-field electroretinograms (ERGs) were recorded from all progeny.
Results: During the course of other experiments, an affected male rat was identified by a reduced amplitude ERG b-wave. When this rat was mated to normal Sprague-Dawley rats, all of the F1 progeny had normal ERG waveforms. When F1 offspring were interbred, 51% of the male offspring had b-wave reductions while all female offspring had normal ERG waveforms. When F1 females were backcrossed to the original affected male, b-wave reductions were noted in both male and female offspring; overall, 46.8% of the backcross progeny exhibited a b-wave reduction. In affected animals, the b-wave was selectively affected as the a-wave appeared to retain normal amplitude and kinetics at 1-4 months old. Cone ERGs were significantly reduced in amplitude and somewhat delayed. Similar ERG results were also obtained under the same stimulus conditions from human patients with complete CSNB (CSNB1).
Conclusions: The inheritance pattern is consistent with an X-linked recessive trait. The electrophysiological results suggest that this mutant rat line may provide another model for CSNB1.