ERG
Transcriptional regulator ERG (Transforming protein ERG)
Publications[править]
The Per2 mouse model developed by Takahashi laboratory is one of the most powerful models to study circadian rhythms in real time. In this study, we report that photoreceptors degenerate in male Per2 mice during aging. Young (2.5- to 5-month-old) and aged (11- to 13.5-month-old) homozygous male Per2 mice and C57BL/6J mice were used for this study. Retina structure and function were investigated via spectral domain optical coherence tomography (SD-OCT), fundus imaging, and electroretinography (ERG). Zonula occludens-1 (ZO-1) immunofluorescence was used to analyze the retinal pigment epithelium (RPE) morphology. Fundus examination revealed no difference between young Per2 and wild-type (WT) mice. However, the fundus of aged Per2 mice showed white deposits, suggestive of age-related drusen-like formation or microglia, which were absent in age-matched WT mice. No differences in retinal structure and function were observed between young Per2 and WT mice. However, with age, Per2 mice showed a significant reduction in total retinal thickness with respect to C57BL/6J mice. The reduction was mostly confined to the photoreceptor layer. Consistent with these results, we observed a significant decrease in the amplitude of a- and b-waves of the ERG in aged Per2 mice. Analysis of the RPE morphology revealed that in aged Per2 mice there was an increase in compactness and eccentricity with a decrease in solidity with respect to the values observed in WT, pointing toward signs of aging in the RPE of Per2 mice. Our data demonstrate that homozygous Per2 mice show photoreceptor degeneration during aging and a premature aging of the RPE.
Keywords
- Per2luc
- aging
- circadian
- mice
- photoreceptors
- retinal pigment epithelium
The processes involved in neurodevelopment and aging have not yet been fully discovered. This is especially challenging in premorbid or borderline situations of neurodegenerative diseases such as Alzheimer's or glaucoma. The retina, as part of the central nervous system, can be considered the easiest and most accessible neural structure that can be analyzed using non-invasive methods. Animal studies of neuroretinal tissue in situations of health and under controlled conditions allow the earliest sex- and aging-induced changes to be analyzed so as to differentiate them from the first signs occurring in manifested disease. This study evaluates differences by age and sex based on intraocular pressure (IOP) and neuroretinal function and structure in healthy young and adult rats before decline due to senescence. For this purpose, eighty-five healthy Long-Evans rats (31 males and 54 females) were analyzed in this 6-month longitudinal study running from childhood to adulthood. IOP was measured by tonometer (Tonolab; Tiolat Oy Helsinki, Finland), neuroretinal function was recorded by flash scotopic and light-adapted photopic negative response electroretinography (ERG) (Roland consult® RETIanimal ERG, Germany) at 4, 16 and 28 weeks of age; and structure was evaluated by in vivo optical coherence tomography (OCT) (Spectralis, Heidelberg® Engineering, Germany). Analyzing both sexes together, IOP was below 20 mmHg throughout the study; retina (R), retinal nerve fiber layer (RNFL) and ganglion cell layer (GCL) thicknesses measured by OCT decreased over time; an increase in ERG signal was recorded at week 16; and no differences were found between right and left eyes. However, analyzing differences by sex revealed that males had higher IOP (even reaching ocular hypertension [>20 mmHg] by the end of the study [7 months of age]), exhibited greater neuroretinal thickness but higher structural percentage loss, and had worse dark- and light-adapted function as measured by ERG than females. This study concludes that age and sex influenced neurodevelopment and neurodegeneration. Different structural and functional degenerative patterns were observed by sex; these occurred earlier and more intensely in males than in age-matched females.
Keywords
- Aging
- Electroretinography
- Neurodegeneration
- Neurodevelopment
- Optical coherence tomography
- Retina
- Sex
The retinal pigment epithelium (RPE) is a specialized monolayer of cells strategically located between the retina and the choriocapillaris that maintain the overall health and structural integrity of the photoreceptors. The RPE is polarized, exhibiting apically and basally located receptors or channels, and performs vectoral transport of water, ions, metabolites, and secretes several cytokines. In vivo noninvasive measurements of RPE function can be made using direct-coupled ERGs (DC-ERGs). The methodology behind the DC-ERG was pioneered by Marmorstein, Peachey, and colleagues using a custom-built stimulation recording system and later demonstrated using a commercially available system. The DC-ERG technique uses glass capillaries filled with Hank's buffered salt solution (HBSS) to measure the slower electrical responses of the RPE elicited from light-evoked concentration changes in the subretinal space due to photoreceptor activity. The prolonged light stimulus and length of the DC-ERG recording make it vulnerable to drift and noise resulting in a low yield of useable recordings. Here, we present a fast, reliable method for improving the stability of the recordings while reducing noise by using vacuum pressure to reduce/eliminate bubbles that result from outgassing of the HBSS and electrode holder. Additionally, power line artifacts are attenuated using a voltage regulator/power conditioner. We include the necessary light stimulation protocols for a commercially available ERG system as well as scripts for analysis of the DC-ERG components: c-wave, fast oscillation, light peak, and off response. Due to the improved ease of recordings and rapid analysis workflow, this simplified protocol is particularly useful in measuring age-related changes in RPE function, disease progression, and in the assessment of pharmacological intervention.
MeSH Terms
- Aging
- Animals
- Electrophysiological Phenomena
- Electroretinography
- Light
- Mice
- Retinal Pigment Epithelium
Chronic oxidative stress is an important mechanism of disease in aging disorders. We do not have a good model to recapitulate AMD and other retinal disorders in which chronic oxidative stress plays an important role. We hypothesized that mice with a combined deficiency in superoxide dismutase 1 (Sod1), DJ-1 (Park-7), and Parkin (Prkn) (triple knock out, TKO) would have an increased level of chronic oxidative stress in the retina, with anatomic and functional consequences just with aging. Eyes of TKO and B6J control mice were (1) monitored with optical coherence tomography (OCT) and electroretinography (ERG) over time, and (2) collected for oxidative marker protein analysis by ELISA or immunohistochemistry and for transmission electron microscopy studies. TKO mice developed qualitative disruptions in outer retinal layers in OCT by 3 months, increased accumulation of fundus spots and subretinal microglia by 6 months of age, significant retinal thinning by 9 months, and decreased ERG signal by 12 months. Furthermore, we found increased accumulation of the oxidative marker malondialdehyde (MDA) in the retina and increased basal laminal deposits (BLD) and mitochondria number and size in the retinal pigment epithelium of aging TKO mice. TKO mice can serve as a platform to study retinal diseases that involve chronic oxidative stress, including macular degeneration, retinal detachment, and ischemic retinopathies. In order to model each of these diseases, additional disease-specific catalysts or triggers could be superimposed onto the TKO mice. Such studies could provide better insight into disease mechanisms and perhaps lead to new therapeutic approaches.
MeSH Terms
- Aging
- Animals
- Biomarkers
- Electroretinography
- Enzyme-Linked Immunosorbent Assay
- Immunohistochemistry
- Malondialdehyde
- Mice
- Mice, Inbred C57BL
- Mice, Knockout
- Microscopy, Electron, Transmission
- Mitochondria
- Oxidative Stress
- Protein Deglycase DJ-1
- Retina
- Retinal Degeneration
- Retinal Pigment Epithelium
- Superoxide Dismutase-1
- Tomography, Optical Coherence
- Ubiquitin-Protein Ligases
Previously we showed that AAV5-mediated expression of either human M- or L-opsin promoted regrowth of cone outer segments and rescued M-cone function in the treated M-opsin knockout (Opn1mw-/-) dorsal retina. In this study, we determined cone viability and window of treatability in aged Opn1mw-/- mice. Cone viability was assessed with antibody against cone arrestin and peanut agglutinin (PNA) staining. The rate of cone degeneration in Opn1mw-/- mice was quantified by PNA staining. AAV5 vector expressing human L-opsin was injected subretinally into one eye of Opn1mw-/- mice at 1, 7, and 15 months old, while the contralateral eyes served as controls. M-cone-mediated retinal function was analyzed 2 and 13 months postinjection by full-field ERG. L-opsin transgene expression and cone outer segment structure were examined by immunohistochemistry. We showed that dorsal M-opsin dominant cones exhibit outer segment degeneration at an early age in Opn1mw-/- mice, whereas ventral S-opsin dominant cones were normal. The remaining M-opsin dominant cones remained viable for at least 15 months, albeit having shortened or no outer segments. We also showed that AAV5-mediated expression of human L-opsin was still able to rescue function and outer segment structure in the remaining M-opsin dominant cones when treatment was initiated at 15 months of age. Our results showing that the remaining M-opsin dominant cones in aged Opn1mw-/- mice can still be rescued by gene therapy is helpful for establishing the window of treatability in future blue cone monochromacy clinical trials.
MeSH Terms
- Aging
- Animals
- Arrestins
- Color Vision Defects
- Disease Models, Animal
- Electroretinography
- Gene Expression Regulation
- Genetic Therapy
- Genetic Vectors
- Mice
- Mice, Inbred C57BL
- Mice, Knockout
- Parvovirinae
- Retina
- Retinal Cone Photoreceptor Cells
- Rod Opsins
To evaluate the repeatability of the steady-state pattern electroretinogram (PERG) and full-field flicker electroretinogram (Flicker ERG) protocols, delivered by the office-based Neuro Optic Vision Assessment (NOVA)™ testing platform, in healthy subjects. Healthy individuals underwent PERG (16° and 24°) and Flicker ERG [fixed luminance (FL) and multi-luminance (ML)] testing protocols. Test-retest repeatability of protocols was calculated using intra-class correlation coefficients (ICC). Reference values of the parameters of the aforementioned tests were also calculated. The ICCs for the PERG parameters ranged from 0.793 to 0.911 (p < 0.001). The ICCs for the Flicker ERG parameters ranged from 0.968 to 0.994 (p < 0.001). A linear regression analysis was applied to assess the impact of age on ERG responses. Age had a significant impact on all PERG parameters (16° or 24°). The phase response of the FL Flicker ERG significantly decreased with age (β = - 0.837, p ≤ 0.001). The FL Flicker ERG Magnitude was also impacted with a significant quadratic effect of age (β = - 0.0047, p = 0.0004). Similarly, the Phase Area Under the Curve (Phase AUC) of the ML Flicker ERG significantly declined with age (β = - 0.007, p = 0.009), and the impact on the Magnitude AUC was significant as well, with a negative quadratic age effect. The PERG and Flicker ERG protocols, delivered by an office-based testing platform, were shown to have good-to-excellent test-retest repeatability when tests were performed in the same order and in immediate succession.
MeSH Terms
- Adult
- Aged
- Aged, 80 and over
- Aging
- Cross-Sectional Studies
- Electroretinography
- Female
- Healthy Volunteers
- Humans
- Male
- Middle Aged
- Prospective Studies
- Reference Values
- Reproducibility of Results
- Retina
- Young Adult
Keywords
- Electrophysiology
- Flicker electroretinogram
- Reference database
- Repeatability
- Steady-state pattern electroretinogram
Adult zebrafish, in contrast to mammals, regenerate neurons in their brain, but the extent and variability of this capacity is unclear. Here we ask whether the loss of various dopaminergic neuron populations is sufficient to trigger their functional regeneration. Both sexes of zebrafish were analyzed. Genetic lineage tracing shows that specific diencephalic ependymo-radial glial (ERG) progenitor cells give rise to new dopaminergic [tyrosine hydroxylase-positive (TH )] neurons. Ablation elicits an immune response, increased proliferation of ERG progenitor cells, and increased addition of new TH neurons in populations that constitutively add new neurons (e.g., diencephalic population 5/6). Inhibiting the immune response attenuates neurogenesis to control levels. Boosting the immune response enhances ERG proliferation, but not addition of TH neurons. In contrast, in populations in which constitutive neurogenesis is undetectable (e.g., the posterior tuberculum and locus ceruleus), cell replacement and tissue integration are incomplete and transient. This is associated with a loss of spinal TH axons, as well as permanent deficits in shoaling and reproductive behavior. Hence, dopaminergic neuron populations in the adult zebrafish brain show vast differences in regenerative capacity that correlate with constitutive addition of neurons and depend on immune system activation. Despite the fact that zebrafish show a high propensity to regenerate neurons in the brain, this study reveals that not all types of dopaminergic neurons are functionally regenerated after specific ablation. Hence, in the same adult vertebrate brain, mechanisms of successful and incomplete regeneration can be studied. We identify progenitor cells for dopaminergic neurons and show that activating the immune system promotes the proliferation of these cells. However, in some areas of the brain this only leads to insufficient replacement of functionally important dopaminergic neurons that later disappear. Understanding the mechanisms of regeneration in zebrafish may inform interventions targeting the regeneration of functionally important neurons, such as dopaminergic neurons, from endogenous progenitor cells in nonregenerating mammals.
MeSH Terms
- Aging
- Animals
- Axons
- Cell Lineage
- Cell Proliferation
- Diencephalon
- Dopaminergic Neurons
- Female
- Immune System Phenomena
- Male
- Microglia
- Nerve Regeneration
- Neural Stem Cells
- Neurogenesis
- Sexual Behavior, Animal
- Zebrafish
Keywords
- GFAP
- Olig2
- anxiety
- mating
- shoaling
- tyrosine hydroxylase
Hydrogen possesses antioxidative effects and cures numerous types of ophthalmopathy, but the mechanism of hydrogen on ROS-induced retinal senescence remains elusive. In this study, retinal morphology revealed that hydrogen reduced the number and size of vitreous black deposits in Bruch's membrane in NaIO3 mice. Hydrogen also reduced ROS levels in the retina as assessed by DHE staining. Moreover, this result was consistent with the downregulation of expression of the oxidative stress hallmark OGG1. These findings suggested that hydrogen can reduce retinal oxidative stress induced by NaIO3, and this result was further verified using the antioxidant ALCAR. Mechanistic analysis revealed that hydrogen significantly inhibited the downregulation of Sirt3 expression, and this notion was confirmed using AICAR, which restores Sirt3 expression and activity. Moreover, hydrogen reduced the expression of p53, p21 and p16 and the number of blue-green precipitations in the retinas of NaIO3 mice as assessed by SA-β-gal staining. We also found that hydrogen decreased the expression of the DNA damage-related protein ATM, cyclinD1 and NF-κB but increased the expression of the DNA repair-related protein HMGB1, suggesting that hydrogen inhibits senescence in retinas of NaIO3 mice. Additionally, OCT examination revealed that hydrogen suppressed retinal high reflex formation significantly and prevented the retina from thinning. This result was supported by ERG assays that demonstrated that hydrogen prevented the reduction in a- and b-wave amplitude induced by NaIO3 in mice. Thus, our data suggest that hydrogen may inhibit retinal senescence by suppressing the downregulation of Sirt3 expression through reduced oxidative stress reactions.
MeSH Terms
- Acetylcarnitine
- Aging
- Animals
- Antioxidants
- Ataxia Telangiectasia Mutated Proteins
- Cyclin D1
- DNA Damage
- Gene Expression Regulation
- HMGB1 Protein
- Humans
- Hydrogen
- Iodates
- Mice
- Oxidative Stress
- Reactive Oxygen Species
- Retina
- Retinal Degeneration
- Sirtuin 3
Keywords
- DNA repair
- Hydrogen
- Retinal oxidative stress injury
- Senescence
- Sirt3
Neuronal ceroid lipofuscinosis (NCL) is the most common group of neurogenetic storage diseases typically beginning in childhood. The juvenile form (JNCL), also known as Batten disease, is the most common form. Vision-related problems are often an early sign, appearing prior to motor and mental deficits. We have previously investigated disease progression with age in the Cln3 KI mouse model for JNCL and showed a decline of visual acuity and a predominant decline of the inner retinal function in mice, similar to human disease. The aim of this study was to further characterize this degeneration by means of flicker ERGs. For the scotopic flicker ERG, we found a significantly lower magnitude for Cln3 KI mice already at 6 months of age for low stimulus frequencies, while the difference declines with increasing frequency. Under photopic conditions there was no magnitude difference at 6 months, but a cumulative magnitude reduction with further aging. For both conditions the phases were similar for both groups. There was a similar magnitude reduction for the responses of both the slow and fast rod pathway in the 15 Hz experiments, and there were no differences in response phase. Low-frequency flicker responses seem to be sensitive to very early disease manifestations, and while the degeneration is associated with a reduction of predominating inner retinal responses in the scotopic flash ERG, this predominance seems not to be related to a selective involvement of the slow and fast rod pathways.
MeSH Terms
- Aging
- Animals
- Disease Models, Animal
- Electroretinography
- Eye Proteins
- Gap Junctions
- Gene Knock-In Techniques
- Membrane Glycoproteins
- Mice
- Mice, Inbred C57BL
- Molecular Chaperones
- Neuronal Ceroid-Lipofuscinoses
- Night Vision
- Retinal Degeneration
- Retinal Rod Photoreceptor Cells
- Visual Pathways
Keywords
- Cln3
- Electroretinography
- Flicker ERG
- Neuronal ceroid lipofuscinosis
- Retinal function
Over an animal's lifespan, neuronal circuits and systems often decline in an inherently heterogeneous fashion. To compare the age-dependent progression of changes in visual behavior with alterations in retinal physiology, we examined phototaxis and electroretinograms (ERGs) in a wild-type D. melanogaster strain (Canton-S) across their lifespan. In aged flies (beyond 50% median lifespan), we found a marked decline in phototaxis, while motor coordination was less disrupted, as indicated by relatively stronger negative geotaxis. These aged flies displayed substantially reduced ERG transient amplitudes while the receptor potentials (RP) remained largely intact. Using a repetitive light flash protocol, we serendipitously discovered two forms of activity-dependent oscillation in the ERG waveforms of young flies: 'light-off' and 'light-on' oscillations. After repeated 500 ms light flashes, light-off oscillations appeared during the ERG off-transients (frequency: 50-120 Hz, amplitude: ∼1 mV). Light-on oscillations (100-200 Hz, ∼0.3 mV) were induced by a series of 50 ms flashes, and were evident during the ERG on-transients. Both forms of oscillation were observed in other strains of D. melanogaster (Oregon-R, Berlin), additional Drosophila species (D. funerbris, D. euronotus, D. hydei, D. americana), and were evoked by a variety of light sources. Both light-off and light-on oscillations were distinct from previously described ERG oscillations in the visual mutant rosA in terms of location within the waveform and frequency. However, within rosA mutants, light-off oscillations, but not light-on oscillations could be recruited by the repetitive light flash protocol. Importantly though, we found that both forms of oscillation were rarely observed in aged flies. Although the physiological bases of these oscillations remain to be elucidated, they may provide important clues to age-related changes in neuronal excitability and synaptic transmission.
MeSH Terms
- Aging
- Animals
- Drosophila melanogaster
- Electroretinography
- Retina
- Synaptic Transmission
Keywords
- On-transient
- aging
- countercurrent apparatus
- lifespan
- off-transient
- receptor potential
Aging is the strongest risk factor for neurodegenerative diseases and extended age results in neuronal degeneration and functional decline in the visual system. Among many contributing factors to age-related deterioration of neurons is an insufficient activation of the Unfolded Protein Response (UPR) in the endoplasmic reticulum (ER) in response to cellular stress. X-box binding protein 1 (XBP1) is a major component of the UPR and is essential for maintaining protein homeostasis and reducing cellular stresses. Herein, we investigate the role of XBP1 in maintaining morphological and functional integrity in retinal neurons during adulthood and the early stages of aging. The basal and induced levels of XBP1 activation in the retina were measured in young adult and aged mice. Conditional knockout (cKO) of XBP1 in retinal neurons was achieved by crossing XBP1 floxed mice with a retina specific Cre-recombinase line (Chx10-Cre). Retinal morphology, neuronal populations including photoreceptors, bipolar cells, and retinal ganglion cells (RGCs), synaptic structure, and microglial activation were examined with immunohistochemistry and staining of retinal sections. Retinal function was evaluated with light-adapted (photopic) and dark adapted (scotopic) electroretinograms. Retinal mitochondrial function and metabolism was assessed by Seahorse XF 24 Extracellular Flux Analyzer. The retinas of aged wild type (WT) mice display a significantly reduced basal level of Xbp1s and compromised activation of ER stress response. In XBP1 cKO mice, significant structural degeneration of the retina, evidenced by thinning of retinal layers and a loss of RGCs, and functional defects indicated by diminished photopic and scotopic ERG b-waves are observed at the age of 12-14 months. Furthermore, discontinuous and disorganized synaptic laminae, colocalized with activated microglia, in the inner plexiform layer is found in the XBP1 cKO retinas. In addition, cKO mice demonstrate a significant increase in ectopic synapses between bipolar cells and photoreceptors, which is strikingly similar to WT mice at 20-24 months of age. These changes are associated with defective retinal glycolysis while mitochondrial respiratory function appears normal in the cKO retina. XBP1 cKO mice at 12-14 months of age show significant structural, functional, and metabolic deficits that closely resemble WT mice twice that age. Our findings suggest that the absence of XBP1, a critical component of the UPR, accelerates age-related retinal neurodegeneration.
MeSH Terms
- Aging
- Animals
- Mice
- Mice, Knockout
- Nerve Degeneration
- Retina
- Unfolded Protein Response
- X-Box Binding Protein 1
Keywords
- Aging
- Neurodegeneration
- Retina
- Unfolded protein response
- X-box binding protein 1
The complement system is a key component of innate immunity comprised of soluble components that form a proteolytic cascade leading to the generation of effector molecules involved in cellular clearance. This system is highly activated not only under general inflammatory conditions such as infections, collagen diseases, nephritis, and liver diseases, but also in focal ocular diseases. However, little is known about the role of the complement system in retinal homeostasis during aging. Using young (6-week-old) and adult (6-month-old) mice in wild type (C57BL/6) and complement knockout strains ([i]C1q[/i] , [i]Mbl a/c[/i] , [i]Fb[/i] , [i]C3[/i] , and [i]C5[/i] ), we compared amplitudes of electroretinograms (ERG) and thicknesses of retinal layers in spectral domain optical coherence tomography between young and adult mice. The ERG amplitudes in adult mice were significantly decreased ([i]p[/i] < 0.001, [i]p[/i] < 0.0001) compared to that of young mice in all complement knockout strains, and there were significant decreases in the inner nuclear layer (INL) thickness in adult mice compared to young mice in all complement knockout strains ([i]p[/i] < 0.0001). There were no significant differences in ERG amplitude or thickness of the INL between young and adult control mice. These data suggest that the complement system plays an important role in maintaining normal retinal integrity over time.
Keywords
- EM
- ERG
- OCT
- aging
- complement system
- retina
Choroidal thickness (CT) evaluation with EDI-OCT in Stargardt Disease (STGD), considering its possible association with some clinical features of the disease. CT was evaluated in 41 STGD patients and in 70 controls. Measurements were performed in the subfoveal position and at 1000 μm nasally and temporally. CT average values in STGD and in the control group were first compared by means of Student's T test. Then, the possible association between CT and some clinical features was evaluated by means of linear regression analysis. Considered clinical parameters were: age, age on onset, duration of the disease, visual acuity, foveal thickness, Fishman clinical phenotype, visual field loss and ERG response. Average CT was not significantly different between controls and STGD patients. In the STGD group the correlation between CT and age (r = 0.22, p = 0.033) and age of onset (r = 0.05, p = 0.424) was modest, while that of CT with disease duration (r = 0.30, p<0.001) was moderate. CT and foveal thickness were also significantly but modestly correlated (r = 0.15, p = 0.033). In our series average CT is not significantly changed in STGD in comparison with the controls. Nevertheless a choroidal thinning may be identified in the more advanced stages of the disease.
MeSH Terms
- ATP-Binding Cassette Transporters
- Adult
- Age of Onset
- Aging
- Choroid
- Female
- Fovea Centralis
- Humans
- Macular Degeneration
- Male
- Organ Size
- Severity of Illness Index
- Stargardt Disease
- Tomography, Optical Coherence
- Visual Acuity
To assess the effect of age and test-retest reliability of the intensity response function of the full-field photopic negative response (PhNR) in normal healthy human subjects. Full-field electroretinograms (ERGs) were recorded from one eye of 45 subjects, and 39 of these subjects were tested on two separate days with a Diagnosys Espion System (Lowell, MA, USA). The visual stimuli consisted of brief (<5 ms) red flashes ranging from 0.00625 to 6.4 phot cd.s/m , delivered on a constant 7 cd/m blue background. PhNR amplitudes were measured at its trough from baseline (BT) and from the preceding b-wave peak (PT), and b-wave amplitude was measured at its peak from the preceding a-wave trough or baseline if the a-wave was not present. The intensity response data of all three ERG measures were fitted with a generalized Naka-Rushton function to derive the saturated amplitude (V ), semisaturation constant (K) and slope (n) parameters. Effect of age on the fit parameters was assessed with linear regression, and test-retest reliability was assessed with the Wilcoxon signed-rank test and Bland-Altman analysis. Holm's correction was applied to account for multiple comparisons. V of BT was significantly smaller than that of PT and b-wave, and the V of PT and b-wave was not significantly different from each other. The slope parameter n was smallest for BT and the largest for b-wave and the difference between the slopes of all three measures were statistically significant. Small differences observed in the mean values of K for the different measures did not reach statistical significance. The Wilcoxon signed-rank test indicated no significant differences between the two test visits for any of the Naka-Rushton parameters for the three ERG measures, and the Bland-Altman plots indicated that the mean difference between test and retest measurements of the different fit parameters was close to zero and within 6% of the average of the test and retest values of the respective parameters for all three ERG measurements, indicating minimal bias. While the coefficient of reliability (COR, defined as 1.96 times the standard deviation of the test and retest difference) of each fit parameter was more or less comparable across the three ERG measurements, the %COR (COR normalized to the mean test and retest measures) was generally larger for BT compared to both PT and b-wave for each fit parameter. The Naka-Rushton fit parameters did not show statistically significant changes with age for any of the ERG measures when corrections were applied for multiple comparisons. However, the V of BT demonstrated a weak correlation with age prior to correction for multiple comparisons, and the effect of age on this parameter showed greater significance when the measure was expressed as a ratio of the V of b-wave from the same subject. V of the BT amplitude measure of PhNR at the best was weakly correlated with age. None of the other parameters of the Naka-Rushton fit to the intensity response data of either the PhNR or the b-wave showed any systematic changes with age. The test-retest reliability of the fit parameters for PhNR BT amplitude measurements appears to be lower than those of the PhNR PT and b-wave amplitude measurements.
MeSH Terms
- Adult
- Aged
- Color Vision
- Electroretinography
- Female
- Healthy Volunteers
- Humans
- Male
- Middle Aged
- Photic Stimulation
- Reproducibility of Results
- Retina
- Retinal Ganglion Cells
- Young Adult
Keywords
- Aging
- Electroretinogram (ERG)
- Intensity response function
- Naka–Rushton
- Photopic negative response (PhNR)
Vision declines during normal aging and in Alzheimer's disease (AD). Although the toxic role of amyloid beta (Aβ) has been established in AD pathogenesis, its influence on the aging retina is unclear. Using APP /PS1ΔE9 transgenic (TG) mice, a classical AD model, the retinal cell function and survival was assessed by electroretinogram (ERG) recordings and immunofluorescent stainings. Strikingly, photopic ERG measurements revealed that the retinal response mediated by cones was preserved in aging TG mice relative to WT controls. In contrast to the cortex, the expression of mutated APP and PS1ΔE9 did not allow to detect Aβ or amyloid plaques in 13-month-old male TG retinae. In addition, the CTFβ/CTFα ratio was significantly lower in retinal samples than that in cortical extracts, suggesting that the nonamyloidogenic pathway may endogenously limit Aβ formation in the retina of male mice. Collectively, our data suggest that retinal-specific processing of amyloid may confer protection against AD and selectively preserve cone-dependent vision during aging.
MeSH Terms
- Aging
- Alzheimer Disease
- Amyloid beta-Protein Precursor
- Animals
- Cell Survival
- Color Vision
- Disease Models, Animal
- Electroretinography
- Fluorescent Antibody Technique
- Male
- Mice, Transgenic
- Retina
- Retinal Cone Photoreceptor Cells
Keywords
- Aging
- Alzheimer's disease
- Color vision
- Electroretinogram
- Photoreceptors
- Retina
Oxidative stress alters physiological function in most biological tissues and can lead to cell death. In the retina, oxidative stress initiates a cascade of events leading to focal loss of RPE and photoreceptors, which is thought to be a major contributing factor to geographic atrophy. Despite these implications, the molecular regulation of RPE oxidative stress under normal and pathological conditions remains largely unknown. A better understanding of the mechanisms involved in regulating RPE and photoreceptors oxidative stress response is greatly needed. To this end we evaluated photoreceptor and RPE changes in mice deficient in DJ-1, a protein that is thought to be important in protecting cells from oxidative stress. Young (3 months) and aged (18 months) DJ-1 knockout (DJ-1 KO) and age-matched wild-type mice were examined. In both group of aged mice, scanning laser ophthalmoscopy (SLO) showed the presence of a few autofluorescent foci. The 18 month-old DJ-1 KO retinas were also characterized by a noticeable increase in RPE fluorescence to wild-type. Optical coherence tomography (OCT) imaging demonstrated that all retinal layers were present in the eyes of both DJ-1 KO groups. ERG comparisons showed that older DJ-1 KO mice had reduced sensitivity under dark- and light-adapted conditions compared to age-matched control. Histologically, the RPE contained prominent vacuoles in young DJ-1 KO group with the appearance of enlarged irregularly shaped RPE cells in the older group. These were also evident in OCT and in whole mount RPE/choroid preparations labeled with phalloidin. Photoreceptors in the older DJ-1 KO mice displayed decreased immunoreactivity to rhodopsin and localized reduction in cone markers compared to the wild-type control group. Lower levels of activated Nrf2 were evident in retina/RPE lysates in both young and old DJ-1 KO mouse groups compared to wild-type control levels. Conversely, higher levels of protein carbonyl derivatives and iNOS immunoreactivity were detected in retina/RPE lysates from both young and old DJ-1 KO mice. These results demonstrate that DJ-1 KO mice display progressive signs of retinal/RPE degeneration in association with higher levels of oxidative stress markers. Collectively this analysis indicates that DJ-1 plays an important role in protecting photoreceptors and RPE from oxidative damage during aging.
MeSH Terms
- Aging
- Animals
- Disease Models, Animal
- Humans
- Mice
- Mice, Inbred C57BL
- Mice, Knockout
- Oxidative Stress
- Photoreceptor Cells, Vertebrate
- Protein Deglycase DJ-1
- Retinal Degeneration
- Retinal Pigment Epithelium
- Rhodopsin
Keywords
- Aging
- DJ-1 knockout
- Histology
- Immunohistology
- Oxidative stress
- Photoreceptors
- Physiology
- Retina
- Retinal degeneration
- Retinal pigment epithelium
- Vacuoles
Common neurodegenerative proteinopathies, such as Alzheimer's disease (AD) and Parkinson's disease (PD), are characterized by the misfolding and aggregation of toxic protein species, including the amyloid beta (Aß) peptide, microtubule-associated protein Tau (Tau), and alpha-synuclein (αSyn) protein. These factors also show toxicity in Drosophila; however, potential limitations of prior studies include poor discrimination between effects on the adult versus developing nervous system and neuronal versus glial cell types. In addition, variable expression paradigms and outcomes hinder systematic comparison of toxicity profiles. Using standardized conditions and medium-throughput assays, we express human Tau, Aß or αSyn selectively in neurons of the adult Drosophila retina and monitor age-dependent changes in both structure and function, based on tissue histology and recordings of the electroretinogram (ERG), respectively. We find that each protein causes a unique profile of neurodegenerative pathology, demonstrating distinct and separable impacts on neuronal death and dysfunction. Strikingly, expression of Tau leads to progressive loss of ERG responses whereas retinal architecture and neuronal numbers are largely preserved. By contrast, Aß induces modest, age-dependent neuronal loss without degrading the retinal ERG. αSyn expression, using a codon-optimized transgene, is characterized by marked retinal vacuolar change, progressive photoreceptor cell death, and delayed-onset but modest ERG changes. Lastly, to address potential mechanisms, we perform transmission electron microscopy (TEM) to reveal potential degenerative changes at the ultrastructural level. Surprisingly, Tau and αSyn each cause prominent but distinct synaptotoxic profiles, including disorganization or enlargement of photoreceptor terminals, respectively. Our findings highlight variable and dynamic properties of neurodegeneration triggered by these disease-relevant proteins in vivo, and suggest that Drosophila may be useful for revealing determinants of neuronal dysfunction that precede cell loss, including synaptic changes, in the adult nervous system.
MeSH Terms
- Aging
- Amyloid beta-Peptides
- Animals
- Animals, Genetically Modified
- Cell Death
- Disease Models, Animal
- Drosophila
- Electroretinography
- Female
- Humans
- Membrane Potentials
- Microelectrodes
- Microscopy, Electron, Transmission
- Neurodegenerative Diseases
- Neurons
- Peptide Fragments
- Retina
- Vision, Ocular
- alpha-Synuclein
- tau Proteins
Keywords
- Alzheimer disease
- Amyloid-beta peptide
- Animal model
- Drosophila
- MAPT
- Neurodegeneration
- Neurophysiology
- Parkinson disease
- SNCA
- Synapses
- Tau
- alpha-synuclein
To quantify the response dynamics of fast adaptation mechanisms of the scotopic ERG in younger and older adults using full-field m-sequence flash stimulation. Scotopic ERGs were measured for a series of flashes separated by 65 ms over a range of 260 ms in 16 younger (20-26, 22.2 ± 2.1; range mean ±1 SD) and 16 older (65-85, 71.2 ± 7) observers without retinal pathology. A short-wavelength (λ peak = 442 nm) LED was used for scotopic stimulation, and the flashes ranged from 0.0001 to 0.01 cd s m(-2). The complete binary kernel series was derived from the responses to the m-sequence flash stimulation, and the first- and second-order kernel responses were analyzed. The first-order kernel represented the response to a single, isolated flash, while the second-order kernels reflected the adapted flash responses that followed a single flash by one or more base intervals. B-wave amplitudes of the adapted flash responses were measured and plotted as a function of interstimulus interval to describe the recovery of the scotopic ERG. A linear function was fitted to the linear portion of the recovery curve, and the slope of the line was used to estimate the rate of fast adaptation recovery. The amplitudes of the isolated flash responses and rates of scotopic fast adaptation recovery were compared between the younger and older participants using a two-way ANOVA. The isolated flash responses and rates of recovery were found to be significantly lower in the older adults. However, there was no difference between the two age groups in response amplitude or recovery rate after correcting for age-related changes in the density of the ocular media. These results demonstrated that the rate of scotopic fast adaptation recovery of normal younger and older adults is similar when stimuli are equated for retinal illuminance.
MeSH Terms
- Adult
- Aged
- Aged, 80 and over
- Aging
- Analysis of Variance
- Dark Adaptation
- Electroretinography
- Female
- Humans
- Male
- Photic Stimulation
- Retina
- Vision, Ocular
- Young Adult
Keywords
- Aging
- Electroretinogram
- Ocular media
- Scotopic adaptation
The objectives of this study were to evaluate the expression of brain and acute leukemia, cytoplasmic (BAALC) gene and erythroblast transformation-specific related gene (ERG) in de novo cases of acute myeloid leukemia (AML) and identify roles in disease progression and outcome. This study included 50 newly diagnosed AML patients, along with 10 apparently healthy normal controls. BAALC and ERG expression was detected in the bone marrow of both patients and controls using real-time RT-PCR. BAALC and ERG expression was detected in 52% of cases but not in any controls. There was a statistically significant correlation between BAALC and ERG gene expression and age (p- value=0.004 and 0.019, respectively). No statistical significance was noted for sex, lymphadenopathy, hepatomegaly, splenomegaly, other hematological findings, immunophenotyping and FAB sub-classification except for ERG gene and FAB (p-value=0.058). A statistical significant correlation was found between response to treatment with ERG expression (p-value=0.028) and age (p-value=0.014). A statistically significant variation in overall survival was evident with patient age, BM blast cells, FAB subgroups, BAALC and ERG expression (p-value= <0.001, 0.045, 0.041, <0.008 and 0.025 respectively). Our results suggest that BAALC and ERG genes are specific significant molecular markers in AML disease progression, response to treatment and survival.
MeSH Terms
- Adult
- Aging
- Biomarkers, Tumor
- Bone Marrow
- Bone Marrow Cells
- Disease Progression
- Egypt
- Female
- Gene Expression Profiling
- Humans
- Leukemia, Myeloid, Acute
- Male
- Middle Aged
- Neoplasm Proteins
- Trans-Activators
- Transcriptional Regulator ERG
- Treatment Outcome
Biological sex and age are considered as two important factors that may influence the function and structure of the retina, an effect that might be governed by sexual hormones such as estrogen. The purpose of this study was to delineate the influence that biological sex and age exert on the retinal function and structure of rodents and also clarify the effect that the estrus cycle might exert on the retinal function of female rats. The retinal function of 50 normal male and female albino Sprague-Dawley (SD) rats was investigated with the electroretinogram (ERG) at postnatal day (P) 30, 60, 100, 200, and 300 (n = 5-6 male and female rats/age). Following the ERG recording sessions, retinal histology was performed in both sexes. In parallel, the retinal function of premenopausal and menopausal female rats aged P540 were also compared. Sex and age-related changes in retinal structure and function were observed in our animal model. However, irrespective of age, no significant difference was observed in ERG and retinal histology obtained from male and female rats. Notwithstanding the above we did however notice that between P60 and P200 there was a gradual increase in ERG amplitudes of female rats compared to males. Furthermore, the ERG of premenopausal female rats aged 18 months old (P540) was larger compared to age-matched menopausal female rats as well as that of male rats. Our results showed that biological sex and age can influence the retinal function and structure of albino SD rats. Furthermore, we showed that cycled female rats have better retinal function compared to the menopausal female rats suggesting a beneficial effect of the estrus cycle on the retinal function.
MeSH Terms
- Aging
- Animals
- Electroretinography
- Estrous Cycle
- Female
- Male
- Rats
- Rats, Sprague-Dawley
- Retina
- Sex Characteristics
Mutations of acid sphingomyelinase (ASMase) cause Niemann-Pick diseases type A and B, which are fatal inherited lipid lysosomal storage diseases, characterized with visceral organ abnormalities and neurodegeneration. However, the effects of suppressing retinal ASMase expression are not understood. The goal of this study was to determine if the disruption of ASMase expression impacts the retinal structure and function in the mouse, and begin to investigate the mechanisms underlying these abnormalities. Acid sphingomyelinase knockout (ASMase KO) mice were utilized to study the roles of this sphingolipid metabolizing enzyme in the retina. Electroretinogram and morphometric analysis were used to assess the retinal function and structure at various ages. Sphingolipid profile was determined by liquid chromatography-mass spectrometry. Western blots evaluated the level of the autophagy marker LC3-II. When compared to control animals, ASMase KO mice exhibited significant age-dependent reduction in ERG a- and b-wave amplitudes. Associated with these functional deficits, morphometric analysis revealed progressive thinning of retinal layers; however, the most prominent degeneration was observed in the photoreceptor and outer nuclear layer. Additional analyses of ASMase KO mice revealed early reduction in ERG c-wave amplitudes and increased lipofuscin accumulation in the retinal pigment epithelium (RPE). Sphingolipid analyses showed abnormal accumulation of sphingomyelin and sphingosine in ASMase KO retinas. Western blot analyses showed a higher level of the autophagosome marker LC3-II. These studies demonstrate that ASMase is necessary for the maintenance of normal retinal structure and function. The early outer retinal dysfunction, outer segment degeneration, accumulation of lipofuscin and autophagosome markers provide evidence that disruption of lysosomal function contributes to the age-dependent retinal degeneration exhibited by ASMase KO mice.
MeSH Terms
- Aging
- Animals
- Electroretinography
- Mice
- Mice, Inbred C57BL
- Mice, Knockout
- Retinal Pigment Epithelium
- Sphingomyelin Phosphodiesterase
We recorded oscillatory potentials (OPs) to document how age impacts on rod- and cone-driven inner retina function. Dark- and light-adapted electroretinogram (ERG) luminance-response functions were recorded in healthy human subjects aged 20 to 39, 40 to 59, and 60 to 82 years. Raw ERG traces (0.1-300 Hz) were filtered (75-300 Hz) to measure OPs trough-to-peak in the time-amplitude domain. Morlet wavelet transform (MWT) allowed documenting OPs time-amplitude-frequency distribution from raw traces. Under dark adaptation, both methods revealed reduced OP amplitudes and prolonged implicit times by 40 years of age. The MWT identified a high-frequency band as the main oscillator, which frequency (150-155 Hz) was unaffected by age. Under light adaptation, most OP peaks were delayed by 40 years of age. Peak-trough measures yielded inconsistent results in relation to luminance. Contrastingly, MWT distinguished two frequency bands at all luminances: high frequency (135 ± 6 Hz) time locked to the onset of early OPs and low frequency (82 ± 7 Hz), giving rise to early and late OPs. By 60 years, there was a consistent power reduction specific to the low-frequency band. Age-related OP changes precede those seen with a- (photoreceptoral) and b-waves (postphotoreceptoral). In addition, MWT allows quantifying distinct low- and high-frequency oscillators in the human retina, which complement traditional OP analysis methods. The identification of an age-independent OP marker (light-adapted high frequency band) opens a new dimension for the screening of retinal degenerations and their impact on inner retina function.
MeSH Terms
- Adaptation, Ocular
- Adult
- Aged
- Aged, 80 and over
- Aging
- Dark Adaptation
- Electroretinography
- Female
- Fourier Analysis
- Humans
- Male
- Middle Aged
- Photic Stimulation
- Reference Values
- Retinal Cone Photoreceptor Cells
- Retinal Rod Photoreceptor Cells
- Young Adult
Keywords
- Morlet wavelet transform
- aging
- electroretinogram
- human
- oscillatory potentials
- retina
To investigate the effect of ageing on the recovery of ocular blood flow, intravitreal oxygen tension and retinal function during and after intraocular pressure (IOP) elevation. Long Evans rats (3- and 14-month-old) underwent acute stepwise IOP elevation from 10 to 120 mmHg (5 mmHg steps each 3 minutes). IOP was then returned to baseline and recovery was monitored for 2 hours. Photopic electroretinograms (ERG) were recorded at each IOP step during stress and at each minute during recovery. Ocular blood flow and vitreal oxygen tension (pO2) were assayed continuously and simultaneously using a combined laser Doppler flow meter (LDF) and an oxygen sensitive fibre-optic probe, respectively. The combined sensor was placed in the vitreous chamber, proximal to the retina. Data were binned into 3 minute intervals during stress and 1 min intervals during recovery. Recovery data was described using a bi-logistic function. Rats of both ages showed similar susceptibility to IOP elevation, with pO2 showing a closer relationship to ERG than LDF. During recovery, both ages showed a distinctive two-phased recovery for all three measures with the exception of the LDF in 3-month-old rats, which showed only 1 phase. In all animals, LDF recovered fastest (<1 minute), followed by pO2 (<10 minute) and ERG (>1 hour). 14-month-old rats showed surprisingly faster and greater LDF recovery compared to the younger group, with similar levels of pO2 recovery. However, the ERG in these middle-aged animals did not fully recover after two hours, despite showing no difference in susceptibility to IOP during stress compared to the young group. Young and middle-aged eyes showed similar susceptibility to IOP elevation in terms of pO2, LDF and ERG. Despite this lack of difference during stress, older eyes did not completely recover function, suggesting a more subtle age-related susceptibility to IOP.
MeSH Terms
- Aging
- Animals
- Electroretinography
- Eye
- Intraocular Pressure
- Ocular Hypertension
- Rats
- Rats, Long-Evans
- Retina
To determine whether the age-regulating protein klotho was expressed in the retina and determine whether the absence of klotho affected retinal function. Immunohistochemistry and qPCR of klotho knockout and wild-type mice were used to detect klotho expression in retina. Immunohistochemistry was used to probe for differences in expression of proteins important in synaptic function, retinal structure, and ionic flux. Electroretinography (ERG) was conducted on animals across lifespan to determine whether decreased klotho expression affects retinal function. Klotho mRNA and protein were detected in the wild-type mouse retina, with protein present in all nuclear layers. Over the short lifespan of the knockout mouse (∼8 weeks), no overt photoreceptor cell loss was observed, however, function was progressively impaired. At 3 weeks of age neither protein expression levels (synaptophysin and glutamic acid decarboxylase [GAD67]) nor retinal function were distinguishable from wild-type controls. However, by 7 weeks of age expression of synaptophysin, glial fibrillary acidic protein (GFAP), and transient receptor potential cation channel subfamily member 1 (TRPM1) decreased while GAD67, post synaptic density 95 (PSD95), and wheat germ agglutinin staining, representative of glycoprotein sialic acid residues, were increased relative to wild-type mice. Accompanying these changes, profound functional deficits were observed as both ERG a-wave and b-wave amplitudes compared with wild-type controls. Klotho is expressed in the retina and is important for healthy retinal function. Although the mechanisms for the observed abnormalities are not known, they are consistent with the accelerating aging phenotype seen in other tissues.
MeSH Terms
- Aging
- Animals
- Blotting, Western
- Disease Models, Animal
- Electroretinography
- Gene Expression Regulation, Developmental
- Glucuronidase
- Immunohistochemistry
- Mice
- Mice, Knockout
- Microscopy, Fluorescence
- Polymerase Chain Reaction
- RNA, Messenger
- Retina
Keywords
- aging
- knockout
- protein expression
Intra-uterine growth restriction (IUGR) has been associated with increased predisposition to age-related complications. We tested the hypothesis that rat offspring models of IUGR would exhibit exacerbated, age-related retinal dysfunction. Female Sprague-Dawley rats (maintained at 11.5% O2 from gestational day 15 to 21 to induce IUGR) and control offspring (maintained at 21% O2 throughout pregnancy) had retinal function assessed at 2 months (young) and 14 months of age (aged) with electroretinogram (ERG) recordings. Retinal anatomy was assessed by immunofluorescence. Deficits in rod-driven retina function were observed in aged IUGR offspring, as evidenced by reduced amplitudes of dark-adapted mixed a-wave V(max) (by 49.3%, P < 0.01), b-wave V(max) (by 42.1%, P < 0.001) and dark-adapted peak oscillatory potentials (by 42.3%, P < 0.01). In contrast to the rod-driven defects specific to aged IUGR offspring, light adapted ERG recordings revealed cone defects in young animals, that were stationary until old age. At 2 months, IUGR offspring had amplitude reductions for both b-wave (V(max) by 46%, P < 0.01) and peak oscillatory potential (V(max) by 38%, P < 0.05). Finally, defects in cone-driven responses were further confirmed by reduced maximal photopic flicker amplitudes at 2 (by 42%, P < 0.001) and 14 months (by 34%, P = 0.06) and critical flicker fusion frequencies at 14 months ( 42 ± 1 Hz, IUGR: 35 ± 2 Hz, P < 0.05). These functional changes were not paralleled by anatomical losses in IUGR offspring retinas. These data support that the developing retina is sensitive to stressors, and that pathways governing cone- and rod-driven function differ in their susceptibilities. In the case of prenatal hypoxia, cone- and rod-driven dysfunction manifest at young and old ages, respectively. We must, therefore, take into account the specific impact that fetal programming might exert on age-related retinal dystrophies when considering related diagnoses and therapeutic applications.
MeSH Terms
- Adaptation, Physiological
- Aging
- Animals
- Darkness
- Female
- Hypoxia
- Pregnancy
- Prenatal Exposure Delayed Effects
- Rats
- Rats, Sprague-Dawley
- Retina
- Retinal Cone Photoreceptor Cells
- Retinal Rod Photoreceptor Cells
Electroretinography (ERG) is a well-established diagnostic procedure for objectively evaluating retinal function. In this study, ERG in beagle dogs, which are a popular experimental animal, was performed to determine the normal range of ERG variables and assess differences between the left and right eyes. ERG findings including rod, combined rod-cone, single-flash cone, and 30-Hz flicker responses were recorded with an LED-electrode in 43 sedated beagle dogs. The subjects were divided into young (< 1 year old), adult (1 ˜ 5 years old), and senile animals (≥ 6 years old). Normal ERG ranges were obtained. Significant differences in b-wave amplitude along with b/a ratio of the combined rod-cone response were found between the young and adult animals as well as young and senile dogs. No significant differences were observed between the left and right eyes. ERG variables in beagle dogs differed by age due to age-related retinal changes. Thus, we propose that normal ERG ranges should be determined according to age in each clinic and laboratory using its own equipment because each institution usually has different systems or protocols for ERG testing.
MeSH Terms
- Aging
- Animals
- Dogs
- Electrodes
- Electroretinography
- Female
- Male
Keywords
- LED-electrode
- age group
- beagle dog
- electroretinography
- normal range
Focal ERG associated with photostress test could be a useful diagnostic method for evaluating macular visual function. The main aim of this study was to evaluate the effect of age on the recovery time constant of the ERG photostress test. The second aim was to assess the sources of variability which affect the measurements. Fifty-four healthy subjects (108 eyes), aged between 21 and 77, with corrected VA of 20/20 or more and absence of any ocular or systemic disease, were recruited. For each eye ERG response to focal (20° in diameter) 42-Hz stimulation was recorded: three series of 200 summations in base conditions and a six series of 42-Hz ERGs (100 summations each) at 10, 40, 80, 180, 300 and 420 s after bleaching by a white spot of light (20° in diameter) from a direct ophthalmoscope (800 cd/m²) pointed at macular region for 30 s. Fourier analysis was performed and amplitude of the first harmonica calculated. The relationship of basal amplitudes with subject age and gender, and the kinetics of macular function recovery were assessed through mixed-effects models. Mean basal amplitude decreases by 0.046 μV for year of life. The recovery after bleaching is proportional to age with an increase of 4.31 s for decade. Restoration of amplitude is slower in older subjects. There is a significant decrease in macular ERG amplitude with age. The macular recovery after photostress shows exponential kinetics that are less efficient in older subjects: this could be related to lower effectiveness of photopigment restoration in advanced age.
MeSH Terms
- Adult
- Age Factors
- Aged
- Aging
- Electroretinography
- Female
- Follow-Up Studies
- Humans
- Light
- Macula Lutea
- Male
- Middle Aged
- Photic Stimulation
- Recovery of Function
- Young Adult
Mutations in the gene encoding human insulin-like growth factor-I (IGF-I) cause syndromic neurosensorial deafness. To understand the precise role of IGF-I in retinal physiology, we have studied the morphology and electrophysiology of the retina of the Igf1(-/-) mice in comparison with that of the Igf1( /-) and Igf1( / ) animals during aging. Serological concentrations of IGF-I, glycemia and body weight were determined in Igf1( / ), Igf1( /-) and Igf1(-/-) mice at different times up to 360days of age. We have analyzed hearing by recording the auditory brainstem responses (ABR), the retinal function by electroretinographic (ERG) responses and the retinal morphology by immunohistochemical labeling on retinal preparations at different ages. IGF-I levels are gradually reduced with aging in the mouse. Deaf Igf1(-/-) mice had an almost flat scotopic ERG response and a photopic ERG response of very small amplitude at postnatal age 360days (P360). At the same age, Igf1( /-) mice still showed both scotopic and photopic ERG responses, but a significant decrease in the ERG wave amplitudes was observed when compared with those of Igf1( / ) mice. Immunohistochemical analysis showed that P360 Igf1(-/-) mice suffered important structural modifications in the first synapse of the retinal pathway, that affected mainly the postsynaptic processes from horizontal and bipolar cells. A decrease in bassoon and synaptophysin staining in both rod and cone synaptic terminals suggested a reduced photoreceptor output to the inner retina. Retinal morphology of the P360 Igf1( /-) mice showed only small alterations in the horizontal and bipolar cell processes, when compared with Igf1( / ) mice of matched age. In the mouse, IGF-I deficit causes an age-related visual loss, besides a congenital deafness. The present results support the use of the Igf1(-/-) mouse as a new model for the study of human syndromic deaf-blindness.
MeSH Terms
- Aging
- Animals
- Deafness
- Disease Models, Animal
- Electroretinography
- Female
- Insulin-Like Growth Factor I
- Male
- Mice
- Mice, 129 Strain
- Mice, Knockout
- Retina
- Vision Disorders
Homocysteine is an amino acid required for the metabolism of methionine. Excess homocysteine is implicated in cardiovascular and neurological disease and new data suggest a role in various retinopathies. Mice lacking cystathionine-beta-synthase (cbs(-/-)) have an excess of retinal homocysteine and develop anatomical abnormalities in multiple retinal layers, including photoreceptors and ganglion cells; heterozygous (cbs( /-)) mice demonstrate ganglion cell loss and mitochondrial abnormalities in the optic nerve. The purpose of the present study was to determine whether elevated homocysteine, due to absent or diminished cbs, alters visual function. We examined cbs(-/-) (3 weeks) and cbs( /-) mice (5, 10, 15, 30 weeks) and results were compared to those obtained from wild type (WT) littermates. Conventional dark- and light-adapted ERGs were recorded, along with dc-ERG to assess retinal pigment epithelial (RPE) function. The visual evoked potential (VEP) was used to assess transmission to the visual cortex. The amplitudes of the major ERG components were reduced in cbs(-/-) mice at age 3 weeks and VEPs were delayed markedly. These findings are consistent with the early retinal disruption observed anatomically in these mice. In comparison, at 3 weeks of age, responses of cbs( /-) mice did not differ significantly from those of WT mice. Functional abnormalities were not observed in cbs( /-) mice until 15 weeks of age, at which time amplitude reductions were noted for the ERG a- and b-wave and the light peak component, but not for other components generated by the RPE. VEP implicit times were delayed in cbs( /-) mice at 15 and 30 weeks, while VEP amplitudes were unaffected. The later onset of functional defects in cbs( /-) mice is consistent with a slow loss of ganglion cells reported previously in the heterozygous mutant. Light peak abnormalities indicate that RPE function is also compromised in older cbs( /-) mice. The data suggest that severe elevations of homocysteine are associated with marked alterations of retinal function while modest homocysteine elevation is reflected in milder and delayed alterations of retinal function. The work lays the foundation to explore the role of homocysteine in retinal diseases such as glaucoma and optic neuropathy.
MeSH Terms
- Aging
- Animals
- Cystathionine beta-Synthase
- Dark Adaptation
- Disease Models, Animal
- Electroretinography
- Evoked Potentials, Visual
- Homocysteine
- Hyperhomocysteinemia
- Mice
- Mice, Inbred C57BL
- Mice, Knockout
- Mice, Mutant Strains
- Retina
- Retinal Pigment Epithelium
- Visual Acuity
- Visual Cortex
{{medline-entry |title=Vision deficits precede structural losses in a mouse model of mitochondrial dysfunction and progressive retinal degeneration. |pubmed-url=https://pubmed.ncbi.nlm.nih.gov/21983042 |abstract=Current animal models of retinal disease often involve the rapid development of a retinal disease phenotype; however, this is at odds with age-related diseases that take many years to manifest clinical symptoms. The present study was performed to examine an apoptosis-inducing factor (Aif)-deficient model, the harlequin carrier mouse (X(hq)X), and determine how mitochondrial dysfunction and subsequent accelerated aging affect the function and structure of the mouse retina. Vision and eye structure for cohorts of 6 X(hq)X and 6 wild type mice at 3, 11, and 15 months of age were studied using in vivo electroretinography (ERG), and optical coherence tomography (OCT). Retinal superoxide levels were determined in situ using dihydroethidium (DHE) histochemistry. Retinal cell counts were quantified post mortem using hematoxylin and eosin (H