8-hydroxy-2--deoxyguanosine and Retinal-Degeneration

The purpose of this study was to evaluate a retinal degeneration (RD) model induced by exposing mice to a blue light-emitting diode (LED), which led to photoreceptor cell death.. RD was induced in BALB/c mice by exposure to a blue LED (460 nm) for 2 hours. Retinal function was examined using scotopic electroretinography (ERG). Histopathological changes were assessed by hematoxylin and eosin (H&E) staining and electron microscopy. Apoptotic cell death was evaluated by terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assay. In addition, retinal inflammation and oxidative stress were evaluated by immunohistochemistry with anti-glial fibrillary acidic protein (GFAP) and anti-8-hydroxy-2'-deoxyguanosine (8-OHdG), respectively.. Scotopic ERG showed that blue LED exposure resulted in a decrease in both a-waves and b-waves in mice retinas in an illuminance-dependent manner. H&E, TUNEL assay, and electron microscopy revealed massive photoreceptor cell death by apoptosis in the central region of the retina. Retinal stress and inflammation were detected by increased expression of GFAP and by electron microscopy findings demonstrating microglia infiltration in the outer nuclear layer and subretinal space. In addition, increased labeling of 8-OHdG was observed in the retinas from blue LED exposure.. These results suggest that blue LED-induced RD may be a useful animal model in which to study the pathogenesis of RD, including age-related macular degeneration, and to evaluate the effects of new therapeutic agents prior to clinical trials, where oxidative stress and inflammation are the underlying RD mechanisms.

Topics: 8-Hydroxy-2'-Deoxyguanosine; Animals; Cell Death; Deoxyguanosine; Electroretinography; Glial Fibrillary Acidic Protein; Immunohistochemistry; In Situ Nick-End Labeling; Light; Male; Mice; Mice, Inbred BALB C; Microscopy, Electron; Photoreceptor Cells, Vertebrate; Radiation Injuries, Experimental; Retinal Degeneration

Cyanidin-3-glucoside (C3G) is a major anthocyanin in berries and a potential nutritional supplement for preventing retinal degeneration. However, the protective mechanism of C3G and its metabolites, protocatechuic acid (PCA) and ferulic acid (FA), remain unclear. The molecular mechanisms of C3G and its metabolites against retinal photooxidative damage in vivo are investigated.. Pigmented rabbits were orally administered C3G, PCA, and FA (0.11 mmol/kg/day) for 3 weeks. Electroretinography, histological analysis, and TUNEL assay showed that C3G and its metabolites attenuated retinal cell apoptosis. The expression of oxidative stress markers were upregulated after light exposure but attenuated by C3G and FA, which may be attributed to the elevated secretion and expression of heme oxygenase (HO-1) and nuclear factor erythroid-2 related factor 2 (Nrf2). C3G, PCA, and FA attenuated the secretion or expression of inflammation-related genes; FA suppressed nuclear factor kappa B (NF-κB) activation. The treatments attenuated the light-induced changes on certain apoptotic proteins and angiogenesis-related cytokines.. C3G and FA reduced light-induced retinal oxidative stress by activating the Nrf2/HO-1 antioxidant pathway. FA attenuated the light-induced retinal inflammation by suppressing NF-κB activation. C3G and its metabolites attenuated the photooxidation-induced apoptosis and angiogenesis in the retina.

Topics: 8-Hydroxy-2'-Deoxyguanosine; Aldehydes; Animals; Anthocyanins; Antioxidants; Apoptosis; Coumaric Acids; Cytokines; Deoxyguanosine; Glucosides; Heme Oxygenase-1; Hydroxybenzoates; In Situ Nick-End Labeling; Light; NF-E2-Related Factor 2; NF-kappa B; Oxidative Stress; Rabbits; Retina; Retinal Degeneration; Signal Transduction; Tyrosine; Up-Regulation

NecroX-5 is a derivative of cyclopentylamino carboxymethylthiazolylindole (NecroX), an inhibitor of necrosis/necroptosis. NecroX-5 has been shown to scavenge mitochondrial reactive oxygen and nitrogen species, and thus preventing necrotic cell death against various kinds of oxidative stress in several tissues, including the brain. To examine the effect of NecroX-5 on retinal degeneration (RD), RD was induced in Sprague-Dawley rats by an intraperitoneal injection of N-methyl-N-nitrosourea and in BALB/c mice by blue light-emitting diode exposure. Scotopic electroretinography recording was used to evaluate retinal function. For histological evaluation, hematoxylin and eosin staining, terminal deoxynucleotidyl transferase dUTP nick end labeling, and immunohistochemistry were performed. Electroretinography recordings showed that a-waves and b-waves were significantly reduced in both RD rats and mice, whereas the amplitudes of both waves were significantly increased in both NecroX-5-treated RD rats and mice compared with untreated RD animals. In hematoxylin and eosin staining and terminal deoxynucleotidyl transferase dUTP nick end labeling assay, the outer nuclear layer where photoreceptors reside appeared to be more preserved, and there were fewer apoptotic cells in NecroX-5-treated RD retinas than in untreated RD retinas. In addition, immunohistochemistry with antiglial fibrillary acidic protein and anti-8-hydroxy-2'-deoxyguanosine showed lower levels of retinal injury and oxidative stress in NecroX-5-treated RD retinas than in untreated RD retinas. These results indicated that NecroX-5 protects retinal neurons from experimentally induced RD, suggesting that NecroX-5 may have a potential for the treatment of RD as a medication.

Topics: 8-Hydroxy-2'-Deoxyguanosine; Animals; Apoptosis; Deoxyguanosine; Disease Models, Animal; Electroretinography; Glial Fibrillary Acidic Protein; Heterocyclic Compounds, 4 or More Rings; In Situ Nick-End Labeling; Male; Mice; Mice, Inbred BALB C; Neuroprotective Agents; Rats; Rats, Sprague-Dawley; Retinal Degeneration; Sulfones

Although hydrogen sulfide (H2S) is generally thought to be a toxic gas, it has been reported to protect various tissues against ischemia-reperfusion injury. In the present study, we histologically investigated whether H2S, using sodium hydrosulfide (NaHS) as its donor, had a protective effect on N-methyl-d-aspartate (NMDA)-induced retinal injury in the rat in vivo. Under ketamine/xylazine anesthesia, male Sprague-Dawley rats were subjected to intravitreal NMDA injection. NaHS (0.163-120 μmol/kg) was intraperitoneally administered 15 min before NMDA injection. Morphometric evaluation at 7 days after NMDA injection showed that intravitreal NMDA injection resulted in ganglion cell loss. NaHS dose-dependently prevented this damage. NaHS (120 μmol/kg) significantly decreased the numbers of TUNEL-positive, 4-hydroxy-2-nonenal-positive, and 8-OHdG-positive cells 12 h after NMDA injection. In another experimental series, we demonstrated that NaHS (120 μmol/kg) significantly reduced the retinal injury induced by intravitreal NOC12 (400 nmol/eye), which was a nitric oxide donor and reported to induce oxidative stress, in the retina, 7 days after intravitreal injection. These results suggested that H2S protects retinal neurons against the injury induced by intravitreal NMDA in rats in vivo. Anti-oxidative activity of H2S are possibly involved in underlying protective mechanisms.

Topics: 8-Hydroxy-2'-Deoxyguanosine; Aldehydes; Animals; Antioxidants; Apoptosis; Cell Survival; Deoxyguanosine; Dose-Response Relationship, Drug; Excitatory Amino Acid Agonists; Hydrogen Sulfide; In Situ Nick-End Labeling; Injections, Intraperitoneal; Intravitreal Injections; Male; N-Methylaspartate; Nitric Oxide Donors; Oxidative Stress; Rats; Rats, Sprague-Dawley; Retinal Degeneration; Retinal Ganglion Cells; Sulfides

The current study investigates the cellular events which trigger activation of proapoptotic Bcl-2-associated × protein (Bax) in retinal cell death induced by all-trans-retinal (atRAL). Cellular events which activate Bax, such as DNA damage by oxidative stress and phosphorylation of p53, were evaluated by immunochemical and biochemical methods using ARPE-19 cells, 661 W cells, cultured neural retinas and a retinal degeneration model, Abca4(-/-)Rdh8(-/-) mice. atRAL-induced Bax activation in cultured neural retinas was examined by pharmacological and genetic methods. Other Bax-related cellular events were also evaluated by pharmacological and biochemical methods. Production of 8-OHdG, a DNA damage indicator, and the phosphorylation of p53 at Ser46 were detected prior to Bax activation in ARPE-19 cells incubated with atRAL. Light exposure to Abca4(-/-)Rdh8(-/-) mice also caused the above mentioned events in conditions of short term intense light exposure and regular room lighting conditions. Incubation with Bax inhibiting peptide and deletion of the Bax gene partially protected retinal cells from atRAL toxicity in cultured neural retina. Necrosis was demonstrated not to be the main pathway in atRAL mediated cell death. Bcl-2-interacting mediator and Bcl-2 expression levels were not altered by atRAL in vitro. atRAL-induced oxidative stress results in DNA damage leading to the activation of Bax by phosphorylated p53. This cascade is closely associated with an apoptotic cell death mechanism rather than necrosis.

Topics: 8-Hydroxy-2'-Deoxyguanosine; Alcohol Oxidoreductases; Animals; Apoptosis; ATP-Binding Cassette Transporters; bcl-2-Associated X Protein; Cell Line; Colorimetry; Deoxyguanosine; Disease Models, Animal; DNA Damage; Gene Deletion; Humans; Immunoblotting; Immunohistochemistry; L-Lactate Dehydrogenase; Mice; Mice, Inbred C57BL; Mice, Transgenic; Organ Culture Techniques; Phosphorylation; Retina; Retinal Degeneration; Retinal Pigment Epithelium; Retinaldehyde; Tomography, Optical Coherence; Tumor Suppressor Protein p53

After our studies on ganglion cell degeneration in the glaucomatous retina, the current work further confirmed the reduction of amacrine cells in the retina after the onset of glaucoma. Present study also tried to understand the possible mechanisms underlying neuronal degeneration in the glaucomatous retina. Changes of expressions in immediate early genes (IEGs), glutamate receptors (GluRs), calcium-binding proteins (CaBPs), 8-hydroxy-deoxyguanosine (8-OH-dG) and nitric oxide synthase (NOS), as well as apoptotic-related factors including caspase 3, bax, and bcl-2 were examined. IEGs such as c-fos and c-jun were induced in the retina of the glaucomatous rat as early as 2 hr after the onset of glaucoma and lasted up to 2 weeks. Expressions of GluRs and CaBPs (i.e., parvalbumin and calbindin D-28k) were observed to be increased in the retinal ganglion cell layer (GCL) and inner nuclear layer (INL) at 3 days and 1 week after the onset of glaucoma. The increase occurred well before and during the phase where significant neuronal death was observed in the GCL and INL of the glaucomatous retinae. Induction of 8-OH-dG was present in both the GCL and INL of the glaucomatous retina at 3 days after the onset of glaucoma before significant neuronal death was observed. Furthermore, confocal microscopy study showed the complete colocalization of immunohistochemical expression of caspase 3 with glial fibrillary acidic protein (GFAP), but not with neuronal nuclei (NeuN). It indicates that astrocytes and Müller cells are involved in the pathological processes of neuronal death. The relationship between the linked factors and neuronal degeneration is also discussed.

Topics: 8-Hydroxy-2'-Deoxyguanosine; Animals; Apoptosis; Astrocytes; Calcium-Binding Proteins; Caspase 3; Caspases; Deoxyguanosine; Disease Models, Animal; Genes, Immediate-Early; Glaucoma; Glial Fibrillary Acidic Protein; Immunohistochemistry; Male; Nerve Degeneration; Neurons; Nitric Oxide Synthase; Rats; Rats, Wistar; Receptors, Glutamate; Retina; Retinal Degeneration; RNA, Messenger; Up-Regulation

Cellular or tissue reduction-oxidation (redox) is crucial in various diseases. The present study was conducted to analyze how tissue redox status is affected by photooxidative stress and whether the exogenous thiol antioxidant N-acetylcysteine (NAC) affects photooxidative stress-induced retinal damage.. Mice were intraperitoneally injected with either NAC (250 mg/kg) or phosphate-buffered saline (PBS) and exposed to white fluorescent light (8000 lux) for 2 hours. Levels of thioredoxin (TRX), glutaredoxin (GRX), and glutathione (GSH), endogenous regulators of redox; 4-hydroxy-2-nonenal (HNE)-modified protein, a marker of lipid peroxidation; and nuclear factor (NF)-kappaB, a redox-sensitive transcription factor in retinal samples, was measured by immunohistochemistry and Western blot or enzymatic recycling assay. Light-induced retinal damage estimated by electroretinography and quantitative immunohistochemistry for 8-hydroxy-2-deoxyguanosine (8OHdG index), a marker of oxidative stress-induced DNA damage, was compared in NAC- and PBS-treated mice.. Upregulation of TRX and HNE-modified protein, decrease of GSH, and nuclear translocation of NF-kappaB were noted after light exposure in PBS-treated mice. These changes were suppressed in NAC-treated mice compared with PBS-treated mice. GRX was not upregulated after light exposure in any mice. The a- and b-wave amplitudes were significantly higher, and the 8OHdG index was significantly lower after light exposure in NAC-treated mice than in PBS-treated mice.. Retinal redox status is altered by intense light and is normalized partially by the effect of NAC on TRX and GSH tissue levels. Manipulation of the tissue redox state by exogenous thiol replenishment may be a useful strategy to prevent retinal photooxidative damage.

Topics: 8-Hydroxy-2'-Deoxyguanosine; Acetylcysteine; Animals; Blotting, Western; Cross-Linking Reagents; Deoxyguanosine; Electroretinography; Glutaredoxins; Glutathione; Light; Male; Mice; Mice, Inbred C57BL; NF-kappa B; Oxidation-Reduction; Oxidative Stress; Oxidoreductases; Proteins; Radiation Injuries, Experimental; Retina; Retinal Degeneration; Thioredoxins

To determine the effects of age and long-term light- or dark-rearing environments on acute, intense-light-mediated retinal degeneration.. Male albino rats were maintained in a dim cyclic light environment or in darkness for as long as 1 year. When aged 2, 4, 8, and 12 months, some rats were given the synthetic antioxidant dimethylthiourea (DMTU) by intraperitoneal injection and were exposed to intense visible light for as long as 24 hours. Uninjected control rats were exposed to light at the same time. Other rats were treated with light of lower intensity for various periods. Two weeks after intense-light treatment, photoreceptor cell degeneration was estimated by determining the level of rhodopsin and by measuring the content of photoreceptor cell DNA. Light-induced changes in retinal DNA were analyzed immediately after exposure by neutral gel electrophoresis and by 8-hydroxy-deoxyguanosine measurements. Expression of the antioxidative stress protein heme oxygenase-1 (HO-1) was determined by northern blot analysis of mRNA in retinal extracts.. At all ages, rats reared in cyclic dim-light conditions had lower rhodopsin levels than did rats reared in darkness; photoreceptor cell DNA levels were unaffected by the rearing environment. Senescent losses in rhodopsin and retinal DNA were significant after rats were 12 months old. Dim-light-reared rats exhibited an age-related increase in retinal light damage susceptibility, whereas dark-reared rats were equally susceptible to damage at all ages. In both types of rats, the mechanism of light-induced cell death involved an apoptotic process, visualized by the pattern of DNA fragments on electrophoretic gels. The process also induced the expression of HO-1 mRNA. Photoreceptor cell loss determined by biochemical measurement, DNA fragmentation, and HO-1 induction were dramatically reduced by the administration of DMTU.. The age-related increase in susceptibility to retinal light damage in rats is influenced by their long-term daily light history. Decreasing retinal irradiance by dark-rearing eliminates the age-related increase in light damage, suggesting a correlation between light environment and retinal gene expression associated with damage. In all rats, retinal light damage resulted in a pattern of DNA fragmentation consistent with apoptotic cell death and in an increased expression of HO-1 mRNA. Antioxidant treatment greatly reduced apoptosis and HO-1 expression. This indicates that light damage involves an oxidative process that may also trigger apoptosis in the retina. The rat aging model may provide useful insights into the role of light environment associated with retinal degeneration in an aging human population.

Topics: 8-Hydroxy-2'-Deoxyguanosine; Aging; Animals; Cell Death; Dark Adaptation; Deoxyguanosine; DNA Fragmentation; Electrophoresis, Polyacrylamide Gel; Free Radical Scavengers; Heme Oxygenase (Decyclizing); Heme Oxygenase-1; Light; Male; Radiation Injuries, Experimental; Rats; Rats, Sprague-Dawley; Retina; Retinal Degeneration; Rhodopsin; RNA, Messenger; Thiourea