Dataset Information

Clock gene expression in the rat retina: effects of lighting conditions and photoreceptor degeneration.

ABSTRACT: Previous studies have shown that, in the Royal College of Surgeon rat, circadian rhythms in the retinal dopaminergic and melatonergic systems are still present after the photoreceptors have degenerated, thus demonstrating that circadian rhythmicity in the mammalian retina can be generated independently from the photoreceptors. The aim of the present study was to investigate the pattern of expression of the clock genes in the retina of the Royal College of Surgeons rat under different lighting conditions. Expression of clock genes was investigated in the retina of normal and dystrophic Royal College of Surgeons rats under 12 h of light/12 h of dark (LD), constant darkness (DD) and constant light (LL) using Real Time Quantitative RT-PCR. Our data indicate that, in control animals, Period1, Period2, Cryptochrome1, Cryptochrome2, Clock, Rora, Rev-Erb alpha and Npas2 mRNA levels showed a significant variation over the sampling period in LD cycles and in DD, whereas Bmal1 mRNA did not show any significant variation. In LL, the transcripts for Per1, Per2, Clock and Rev-Erb alpha showed significant temporal variations. In the dystrophic retina, only Per1 and Per2 mRNA levels showed a temporal variation over the 20-h period. Our work indicates that degeneration of the photoreceptor cells dramatically affected the expression levels and patterns of many clock genes. Finally, the present study suggests that investigating the expression pattern of clock genes using the whole retina or animals with photoreceptor degeneration may not provide any definitive answers about the working of the retinal circadian clock system.

SUBMITTER: Tosini G

PROVIDER: S-EPMC1994112 | biostudies-literature | 2007 Jul

REPOSITORIES: biostudies-literature

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Clock gene expression in the rat retina: effects of lighting conditions and photoreceptor degeneration.

Tosini Gianluca G Kasamatsu Manami M Sakamoto Katsuhiko K

Brain research 20070523

Previous studies have shown that, in the Royal College of Surgeon rat, circadian rhythms in the retinal dopaminergic and melatonergic systems are still present after the photoreceptors have degenerated, thus demonstrating that circadian rhythmicity in the mammalian retina can be generated independently from the photoreceptors. The aim of the present study was to investigate the pattern of expression of the clock genes in the retina of the Royal College of Surgeons rat under different lighting co ...[more]

PMID: 17560558

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Project description:Oxidative stress and inflammation play key roles in the light damage (LD) model of photoreceptor degeneration, as well as in age-related macular degeneration (AMD). We sought to investigate whether Berberine (BBR), an antioxidant herb extract, would protect the retina against light-induced degeneration. To accomplish this, Balb/c mice were treated with BBR or PBS via gavage for 7 days, and then were placed in constant cool white light-emitting diode (LED) light (10,000 lux) for 4 h. Retinal function and degeneration were evaluated by histology, electroretinography (ERG) and optical coherence tomography (OCT) at 7d after LD. Additionally, mRNA levels of cell-type specific, antioxidant, and inflammatory genes were compared 7d after LD. Photoreceptor DNA fragmentation was assessed via the terminal deoxynucleotidyl transferase dUTP nick end-labeling (TUNEL) assay. LD resulted in substantial photoreceptor-specific cell death. Histological analysis using plastic sections showed dosing with BBR preserved photoreceptors. The ERG analysis demonstrated functional protection by BBR in rod-b, -a, and cone-b waves. In OCT images, mice receiving PBS showed severe thinning and disorganization of the photoreceptor layer 7 days after LD, whereas mice treated with BBR had significantly less thinning and disorganization. Consistent with OCT results, the mRNA levels of Rho in the NSR, and Rpe65 and Mct3 in the RPE, were significantly higher in mice treated with BBR. The numbers of TUNEL-positive photoreceptors were significantly decreased in BBR-treated mice. The retinal mRNA levels of oxidative stress genes, the number of microglia/macrophages, and the malondialdehyde (MDA) immunolabeling were significantly lower in BBR-treated mice compared to controls 48 h after LD, which indicates oxidative stress was reduced by BBR in light-damaged eyes. In conclusion, systemic BBR is protective against light-induced retinal degeneration associated with diminished oxidative stress in the retina. These results suggest that BBR may be protective against retinal diseases involving oxidative stress.

Dataset Information

Clock gene expression in the rat retina: effects of lighting conditions and photoreceptor degeneration.

Publications

Clock gene expression in the rat retina: effects of lighting conditions and photoreceptor degeneration.

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