The Effects of Ambient Light Exposure on the Retinopathy Induced by Targeted Deletion at Codon 307 of the Mouse Rds-Peripherin Gene

Abstract

Abstract: : Purpose: To study the effects of ambient light exposure on the development of the degenerative retinopathy found in mice homozygous for a 1 base deletion at codon 307 of the murine rds-Peripherin gene. Methods: Homozygous litters were born and reared in either darkness or ambient lighting (12 hrs on, 12 hrs off). Animals were analysed by serial Ganzfeld electroretinography (ERG). The animals were sacrificed at 12 weeks of age and the eyes were resin embedded. Outer nuclear layer (ONL) cell counts were carried out on semi-thin retinal sections. A 2-sample t-test was used to compare both b wave amplitudes and ONL nuclear counts between litters. Results: No rod-isolated ERG responses were recorded in any of the animals studied. Cone-dominated responses were recorded to the maximal intensity flash presented in the dark-adapted state and to the same intensity flash presented at 0.5 Hz and 10 Hz against a rod-suppressing background. No statistically significant differences were noted in ERG b wave amplitudes between light-reared and dark-reared animals. At 12 weeks of age the ONL was reduced to 2 -3 rows of photoreceptor nuclei. ONL nuclear counts showed no statistically significant differences between light-reared and dark-reared animals. Conclusions: Ambient light exposure does not adversely affect the severity of the retinopathy found in mice homozygous for the 1 base deletion at codon 307 of the rds-Peripherin gene.

Keywords: animal model • dark/light adaptation • retinal degenerations: hereditary