Abstract
Purpose :
The circadian clock plays important roles in the regulation of retinal functions and physiology. Previous study has indicated that removal of the clock gene, Bmal1, from the neural retina alters photosensitivity, spectral identity and cone viability during aging in mice. Environmental circadian disruption (ECD, e.g. shift work, jet lag, living in Arctic etc.) has been shown to be deleterious for the health, but no study has investigated the effect of ECD in the retina. In this study we investigated the effect of ECD on the retina functioning and circuitry.
Methods :
PER2::LUC and C57BL/6 mice were placed in a light tight isolated chamber and expose to ECD light cycles by advancing the time of light-on at 6 hours/week for 4 weeks. For control group, mice were exposed to a 12/12 Light/Dark cycle without any shifts. After 4 weeks of ECD, PER2::LUC mice (4-5 mo. old) were sacrificed and the retina, the retinal pigment epithelium (RPE) and the cornea were isolated and cultured for bioluminescence measurement. C57BL/6 mice (3 mo. old) were also exposed to ECD and subjected to both scotopic and photic electroretinogram (ERG) recording at the end of the fourth week. Retinal circuitry and morphology of C57BL/6 mice was evaluated by immunostaining (peanut agglutinin for cone photoreceptors, anti-PKCα for rod bipolar cell, anti-PSD95 for postsynaptic density).
Results :
The circadian rhythm in PER2::LUC bioluminescence revealed that ECD altered circadian phase and period in retina and RPE but not in cornea. The amplitude of scotopic b-wave was significantly decreased in the mice subject to ECD. Consistently with this observation the dendric branching of rod bipolar cells was also reduced. The amplitude of photic ERG and the viability of the cone photoreceptors were not affected by ECD.
Conclusions :
Our data indicate that the ECD affect the retinal circadian system, the retinal functioning and circuitry. Our results suggest that disruption of circadian rhythms may induce visual impairment.
This is a 2021 ARVO Annual Meeting abstract.