Nuclear Layer (nuclear + layer)

Distribution by Scientific Domains

Kinds of Nuclear Layer

  • inner nuclear layer
  • outer nuclear layer


  • Selected Abstracts


    Expression of AP-2, in the developing chick retina

    DEVELOPMENTAL DYNAMICS, Issue 11 2008
    Xiaodong Li
    Abstract AP-2 is a family of transcription factors that play important roles during embryonic development. Two AP - 2 genes, AP - 2, and AP - 2,, have previously been characterized in chick retina. Here, we demonstrate that a third member of the chicken AP-2 family, AP - 2,, is primarily expressed in the retina and brain, with highest levels at embryonic days 7 to 11. By in situ hybridization and immunohistochemical analysis, we show that AP - 2, RNA and protein are found in a subset of ganglion cells in embryonic chick retina. Co-immunostaining with anti-Brn3a and anti,AP-2, antibodies indicates that approximately one-third of Brn3a-positive ganglion cells express AP-2,. AP - 2, RNA but not AP-2, protein is also found in cells located in the outer half of the inner nuclear layer. The spatial and temporal distribution of AP-2, protein in the retina suggests a transient role in a subset of late-born ganglion cells likely involving axonal trafficking or pathfinding. Developmental Dynamics 237:3210,3221, 2008. © 2008 Wiley-Liss, Inc. [source]


    Genetic dissection reveals two separate pathways for rod and cone regeneration in the teleost retina

    DEVELOPMENTAL NEUROBIOLOGY, Issue 5 2008
    Ann C. Morris
    Abstract Development of therapies to treat visual system dystrophies resulting from the degeneration of rod and cone photoreceptors may directly benefit from studies of animal models, such as the zebrafish, that display continuous retinal neurogenesis and the capacity for injury-induced regeneration. Previous studies of retinal regeneration in fish have been conducted on adult animals and have relied on methods that cause acute damage to both rods and cones, as well as other retinal cell types. We report here the use of a genetic approach to study progenitor cell responses to photoreceptor degeneration in the larval and adult zebrafish retina. We have compared the responses to selective rod or cone degeneration using, respectively, the XOPS-mCFP transgenic line and zebrafish with a null mutation in the pde6c gene. Notably, rod degeneration induces increased proliferation of progenitors in the outer nuclear layer (ONL) and is not associated with proliferation or reactive gliosis in the inner nuclear layer (INL). Molecular characterization of the rod progenitor cells demonstrated that they are committed to the rod photoreceptor fate while they are still mitotic. In contrast, cone degeneration induces both Müller cell proliferation and reactive gliosis, with little change in proliferation in the ONL. We found that in both lines, proliferative responses to photoreceptor degeneration can be observed as 7 days post fertilization (dpf). These two genetic models therefore offer new opportunities for investigating the molecular mechanisms of selective degeneration and regeneration of rods and cones. © 2008 Wiley Periodicals, Inc. Develop Neurobiol, 2008. [source]


    Time course analysis of gene expression during light-induced photoreceptor cell death and regeneration in albino zebrafish

    DEVELOPMENTAL NEUROBIOLOGY, Issue 8 2007
    Sean C. Kassen
    Abstract Constant intense light causes apoptosis of rod and cone photoreceptors in adult albino zebrafish. The photoreceptors subsequently regenerate from proliferating inner nuclear layer (INL) progenitor cells that migrate to the outer nuclear layer (ONL) and differentiate into rods and cones. To identify gene expression changes during this photoreceptor regeneration response, a microarray analysis was performed at five time points during the light treatment. The time course included an early time point during photoreceptor death (16 h), later time points during progenitor cell proliferation and migration (31, 51, and 68 h) and a 96 h time point, which likely corresponds to the initial photoreceptor differentiation. Mean expression values for each gene were calculated at each time point relative to the control (0 h light exposure) and statistical analysis by one-way ANOVA identified 4567 genes exhibiting significant changes in gene expression along the time course. The genes within this data set were clustered based on their temporal expression patterns and proposed functions. Quantitative real-time PCR validated the microarray expression profiles for selected genes, including stat3 whose expression increased markedly during the light exposure. Based on immunoblots, both total and activated Stat3 protein expression also increased during the light treatment. Immunolocalization of Stat3 on retinal tissue sections demonstrated increased expression in photoreceptors and Müller glia by 16 h of light exposure. Some of the Stat3-positive Müller cells expressed PCNA at 31 h, suggesting that Stat3 may play a role in signaling a subset of Müller cells to proliferate during the regeneration response. © 2007 Wiley Periodicals, Inc. Develop Neurobiol, 2007. [source]


    Changing patterns of ganglion cell coupling and connexin expression during chick retinal development

    DEVELOPMENTAL NEUROBIOLOGY, Issue 4 2002
    David L. Becker
    Abstract We have used dye injection and immunolabeling to investigate the relationship between connexin (Cx) expression and dye coupling between ganglion cells (GCs) and other cells of the embryonic chick retina between embryonic days 5 and 14 (E5,14). At E5, GCs were usually coupled, via soma-somatic or dendro-somatic contacts, to only one or two other cells. Coupling increased with time until E11 when GCs were often coupled to more than a dozen other cells with somata in the ganglion cell layer (GCL) or inner nuclear layer (INL). These coupled clusters occupied large areas of the retina and coupling was via dendro-dendritic contacts. By E14, after the onset of synaptogenesis and at a time of marked cell death, dye coupling was markedly decreased with GCs coupled to three or four partners. At this time, coupling was usually to cells of the same morphology, whereas earlier coupling was heterogeneous. Between E5 and E11, GCs were sometimes coupled to cells of neuroepithelial morphology that spanned the thickness of the retina. The expression of Cx 26, 32, and 43 differed and their distribution changed during the period studied, showing correlation with events such as proliferation, migration, and synaptogenesis. These results suggest specific roles for gap junctions and Cx's during retinal development. © 2002 Wiley Periodicals, Inc. J Neurobiol 52: 280,293, 2002 [source]


    Loss of photic entrainment at low illuminances in rats with acute photoreceptor degeneration

    EUROPEAN JOURNAL OF NEUROSCIENCE, Issue 8 2009
    Domitille L. Boudard
    Abstract In several species, an acute injection of N -methyl- N -nitrosourea (MNU) induces a retinal degeneration characterized principally by a rapid loss of the outer nuclear layer, the other layers remaining structurally intact. It has, however, also been reported that down-regulation of melanopsin gene expression is associated with the degeneration and is detectable soon after injection. Melanopsin is expressed by a small subset of intrinsically photosensitive retinal ganglion cells and plays an important role in circadian behaviour photoentrainment. We injected MNU into Long Evans rats and investigated the ability of animals to entrain to three light/dark cycles of different light intensities (300, 15 and 1 lux). Control animals entrained their locomotor activity rhythms to the three cycles. In contrast, MNU-treated animals could only entrain properly to the 300 lux cycle. For the 15 lux cycle, their phase angle was much altered compared with control animals, and for the 1 lux cycle, MNU-injected animals were unable to photoentrain and exhibited an apparent free-run activity pattern with a period of 24.3 h. Subsequent to behavioural studies the animals were killed and rod, cone, melanopsin expression and melanopsin-expressing cells were quantified. Rod and cone loss was almost complete, melanopsin protein was reduced by 83% and melanopsin-expressing cells were reduced by 37%. Our study provides a comprehensive model of photoreceptor degeneration at the adult stage and a simple and versatile method to investigate the relation between retinal photoreceptors and the circadian system. [source]


    Characterization and synaptic connectivity of melanopsin-containing ganglion cells in the primate retina

    EUROPEAN JOURNAL OF NEUROSCIENCE, Issue 10 2007
    Patricia R. Jusuf
    Abstract Melanopsin is a photopigment expressed in retinal ganglion cells, which are intrinsically photosensitive and are also involved in retinal circuits arising from rod and cone photoreceptors. This circuitry, however, is poorly understood. Here, we studied the morphology, distribution and synaptic input to melanopsin-containing ganglion cells in a New World monkey, the common marmoset (Callithrix jacchus). The dendrites of melanopsin-containing cells in marmoset stratify either close to the inner nuclear layer (outer stratifying), or close to the ganglion cell layer (inner stratifying). The dendritic fields of outer-stratifying cells tile the retina, with little overlap. However, the dendritic fields of outer-stratifying cells largely overlap with the dendritic fields of inner-stratifying cells. Thus, inner-stratifying and outer-stratifying cells may form functionally independent populations. The synaptic input to melanopsin-containing cells was determined using synaptic markers (antibodies to C-terminal binding protein 2, CtBP2, for presumed bipolar synapses, and antibodies to gephyrin for presumed amacrine synapses). Both outer-stratifying and inner-stratifying cells show colocalized immunoreactive puncta across their entire dendritic tree for both markers. The density of CtBP2 puncta on inner dendrites was about 50% higher than that on outer dendrites. The density of gephyrin puncta was comparable for outer and inner dendrites but higher than the density of CtBP2 puncta. The inner-stratifying cells may receive their input from a type of diffuse bipolar cell (DB6). Our results are consistent with the idea that both outer and inner melanopsin cells receive bipolar and amacrine input across their dendritic tree. [source]


    Dark-rearing-induced reduction of GABA and GAD and prevention of the effect by BDNF in the mouse retina

    EUROPEAN JOURNAL OF NEUROSCIENCE, Issue 8 2006
    Eun-Jin Lee
    Abstract Gamma-aminobutyric acid (GABA) is an important retinal neurotransmitter. We studied the expression of GABA, glutamate decarboxylase 65 (GAD65) and GAD67 by immunocytochemistry and Western blot, in the retinas of control and dark-reared C57BL/6J black mice. This study asked three questions. First, is visual input necessary for the normal expression of GABA, GAD65 and GAD67? Second, can the retina recover from the effects of dark-rearing if returned to a normal light,dark cycle? Third, does BDNF prevent the influence of dark-rearing on the expression of GABA and GAD? At postnatal day 10 (P10), before eye opening, GABA immunoreactivity was present in the ganglion cell layer (GCL), in the innermost rows of the inner nuclear layer (INL) and throughout the inner plexiform layer (IPL) of control and dark-reared retinas. In P30 control retinas, GABA immunoreactivity showed similar patterns to those at P10. However, in P30 dark-reared retinas, the density of GABA-immunoreactive cells was lower in both the INL and GCL than in control retinas. In addition, visual deprivation retarded GABA immunoreactivity in the IPL. Western blot analysis showed corresponding differences in the levels of GAD65 but not of GAD67 expression between control and dark-rearing conditions. In our study, dark-rearing effects were reversed when the mice were put in normal cyclic light,dark conditions for 2 weeks. Moreover, dark-reared retinas treated with BDNF showed normal expression of both GABA and GAD65. Our data indicate that normal expression of GABA and GAD65 is dependent on visual input. Furthermore, the data suggest that BDNF controls this dependence. [source]


    Radial migration of developing microglial cells in quail retina: A confocal microscopy study

    GLIA, Issue 3 2004
    Ana Sánchez-López
    Abstract Microglial cells spread within the nervous system by tangential and radial migration. The cellular mechanism of tangential migration of microglia has been described in the quail retina but the mechanism of their radial migration has not been studied. In this work, we clarify some aspects of this mechanism by analyzing morphological features of microglial cells at different steps of their radial migration in the quail retina. Microglial cells migrate in the vitreal half of the retina by successive jumps from the vitreal border to progressively more scleral levels located at the vitreal border, intermediate regions, and scleral border of the inner plexiform layer (IPL). The cellular mechanism used for each jump consists of the emission of a leading thin radial process that ramifies at a more scleral level before retraction of the rear of the cell. Hence, radial migration and ramification of microglial cells are simultaneous events. Once at the scleral border of the IPL, microglial cells migrate through the inner nuclear layer to the outer plexiform layer by another mechanism: they retract cell processes, become round, and squeeze through neuronal bodies. Microglial cells use radial processes of s-laminin-expressing Müller cells as substratum for radial migration. Levels where microglial cells stop and ramify at each jump are always interfaces between retinal strata with strong tenascin immunostaining and strata showing weak or no tenascin immunoreactivity. When microglial cell radial migration ends, tenascin immunostaining is no longer present in the retina. These findings suggest that tenascin plays a role in the stopping and ramification of radially migrating microglial cells. © 2004 Wiley-Liss, Inc. [source]


    Age-related reduction in retinal deimination levels in the F344BN rat

    AGING CELL, Issue 3 2008
    Sanjoy K. Bhattacharya
    Summary Increased deimination and peptidyl arginine deiminase type 2 (PAD2) expression has been observed in age-related neurodegenerative diseases without discrimination between their aging and disease component. Here, we describe reduced levels of deimination commensurate with reduced protein, mRNA and activity of peptidylarginine deiminase type 2 in the retina, optic nerve and plasma of aged rats when compared to young rats. The decrease was significant in the ganglion cell layer, inner plexiform layer and inner nuclear layer. Because our observations suggest reduced deimination is a consequence of aging, we conclude that increased deimination must be a consequence of disease. Our findings are important to understand late-onset and progressive diseases such as glaucoma, pseudoexfoliation syndrome, age-related macular degeneration and Oguchi's disease. [source]


    Histopathological studies on viral nervous necrosis of sevenband grouper, Epinephelus septemfasciatus Thunberg, at the grow-out stage

    JOURNAL OF FISH DISEASES, Issue 7 2004
    S Tanaka
    Abstract Viral nervous necrosis caused by sevenband grouper nervous necrosis virus (SGNNV) has occurred in grow-out stages (0,3 years old) of sevenband grouper, Epinephelus septemfasciatus, since the 1980s. In the present study, based on histopathological features of the central nervous system (CNS) in naturally diseased fish, pernasal infection experiments using grow-out fish were performed and pernasal infection was established as a putative invasion route of SGNNV. The definite SGNNV-targeted cells were determined by histopathological studies including indirect fluorescent antibody test and electron microscopy. Nerve cells in the olfactory lobe were most extensively necrotized with vacuolation followed by infiltration of microglia and macrophages. Purkinje cells and Golgi cells were extensively infected in the cerebellum. Megalocells and small nerve cell nuclei were also infected in the preoptic area, thalamus, medulla oblongata and spinal cord. Only a few small nerve cells were infected in the olfactory bulb and optic tectum. The retina of some diseased fish displayed vacuolated bipolar cells of the inner nuclear layer and in the ganglion cell layer. These SGNNV-infected nerve cells displayed viroplasmic inclusions containing virions, vacuoles and myelin-like structures. Based on observed histopathological changes, the lesion of the CNS was characterized by encephalitis but not encephalopathy. [source]


    Pregnenolone Sulfate, a Naturally Occurring Excitotoxin Involved in Delayed Retinal Cell Death

    JOURNAL OF NEUROCHEMISTRY, Issue 6 2000
    C. Cascio
    Abstract: The present study was designed to investigate the neurosteroid pregnenolone sulfate (PS), known for its ability to modulate NMDA receptors and interfere with acute excitotoxicity, in delayed retinal cell death. Three hours after exposure of the isolated and intact retina to a 30-min PS pulse, DNA fragmentation as assessed by genomic DNA gel electrophoresis and a modified in situ terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end-labeling (TUNEL) method appeared concurrently with an increase in superoxide dismutase (SOD) activity and thiobarbituric acid-reactive substances (TBARS) levels. At 7 h, the increased amount of DNA laddering was accompanied by a higher number of TUNEL-positive cells in the inner nuclear and ganglion cell layers. Necrotic signs were characterized by DNA smear migration, lactate dehydrogenase (LDH) release, and damage mainly in the inner nuclear layer. PS-induced delayed cell death was markedly reduced by the NMDA receptor antagonists 4-(3-phosphonopropyl)-2-piperazinecarboxylic acid and 3,-hydroxy-5,-pregnan-20-one sulfate but completely blocked after concomitant addition of the non-NMDA receptor antagonist 6-cyano-7-nitroquinoxaline-2,3-dione. Steroids with antioxidant properties (progesterone, dehydroepiandrosterone and its sulfate ester, and 17,-estradiol) differently prevented PS-induced delayed cell death. Cycloheximide treatment protected against DNA fragmentation and LDH release but failed to prevent the rise in SOD activity and TBARS level. We conclude that a brief PS pulse causes delayed cell death in a slowly evolving apoptotic fashion characterized by a cycloheximide-sensitive death program downstream of reactive oxygen species generation and lipid peroxidation, turning into secondary necrosis in a retinal cell subset. [source]


    Differential distribution of voltage-gated potassium channels Kv 1.1,Kv1.6 in the rat retina during development

    JOURNAL OF NEUROSCIENCE RESEARCH, Issue 1 2007
    M. Höltje
    Abstract The discharge behavior of neurons depends on a variable expression and sorting pattern of voltage-dependent potassium (Kv) channels that changes during development. The rodent retina represents a neuronal network whose main functions develop after birth. To obtain information about neuronal maturation we analyzed the expression of subunits of the Kv1 subfamily in the rat retina during postnatal development using immunocytochemistry and immunoelectron microscopy. At postnatal day 5 (P5) all the ,-subunits of Kv1.1,Kv1.6 channels were found to be expressed in the ganglion cell layer (GCL), most of them already at P1 or P3. Their expression upregulates postnatally and the pattern and distribution change in an isoform-specific manner. Additionally Kv1 channels are found in the outer and inner plexiform layer (OPL, IPL) and in the inner nuclear layer (INL) at different postnatal stages. In adult retina the Kv 1.3 channel localizes to the inner and outer segments of cones. In contrast, Kv1.4 is highly expressed in the outer retina at P8. In adult retina Kv1.4 occurs in rod inner segments (RIS) near the connecting cilium where it colocalizes with synapse associated protein SAP 97. By using confocal laser scanning microscopy we showed a differential localization of Kv1.1-1.6 to cholinergic amacrine and rod bipolar cells of the INL of the adult retina. © 2006 Wiley-Liss, Inc. [source]


    Spatial patterning of cholinergic amacrine cells in the mouse retina

    THE JOURNAL OF COMPARATIVE NEUROLOGY, Issue 1 2008
    Irene E. Whitney
    Abstract The two populations of cholinergic amacrine cells in the inner nuclear layer (INL) and the ganglion cell layer (GCL) differ in their spatial organization in the mouse retina, but the basis for this difference is not understood. The present investigation examined this issue in six strains of mice that differ in their number of cholinergic cells, addressing how the regularity, packing, and spacing of these cells varies as a function of strain, layer, and density. The number of cholinergic cells was lower in the GCL than in the INL in all six strains. The nearest neighbor and Voronoi domain regularity indexes as well as the packing factor were each consistently lower for the GCL. While these regularity indexes and the packing factor were largely stable across variation in density, the effective radius was inversely related to density for both the GCL and INL, being smaller and more variable in the GCL. Consequently, despite the lower densities in the GCL, neighboring cells were more likely to be positioned closer to one another than in the higher-density INL, thereby reducing regularity and packing. This difference in the spatial organization of cholinergic cells may be due to the cells in the GCL having been passively displaced by fascicles of optic axons and an expanding retinal vasculature during development. In support of this interpretation, we show such displacement of cholinergic somata relative to their dendritic stalks and a decline in packing efficiency and regularity during postnatal development that is more severe for the GCL. J. Comp. Neurol. 508:1,12, 2008. © 2008 Wiley-Liss, Inc. [source]


    Differential output of the high-sensitivity rod photoreceptor: AII amacrine pathway

    THE JOURNAL OF COMPARATIVE NEUROLOGY, Issue 6 2008
    Artemis Petrides
    A population of ON cone bipolar cells is not coupled to AII amacrine cells. Neurobiotin (red) diffusion away from an injected AII amacrine cell (top right) at the level of bipolar cell somas in the inner nuclear layer of the rabbit retina. The somas of all depolarizing bipolar cells were labeled with antisera to G0, (green), and rod bipolars are labeled with antisera to PKC, (blue). G0, -outlined somas without PKC, or Neurobiotin are non-coupled ON cone bipolar cells. J. Comp. Neurol. 507:1653,1662, 2008. © 2008 Wiley-Liss, Inc. [source]


    Differential output of the high-sensitivity rod photoreceptor: AII amacrine pathway

    THE JOURNAL OF COMPARATIVE NEUROLOGY, Issue 5 2008
    Artemis Petrides
    A population of ON cone bipolar cells is not coupled to AII amacrine cells. Neurobiotin (red) diffusion away from an injected AII amacrine cell (top right) at the level of bipolar cell somas in the inner nuclear layer of the rabbit retina. The somas of all depolarizing bipolar cells were labeled with antisera to G0, (green), and rod bipolars are labeled with antisera to PKC, (blue). G0, -outlined somas without PKC, or Neurobiotin are non-coupled ON cone bipolar cells. J. Comp. Neurol. 507:1653-1662, 2008. © 2008 Wiley-Liss, Inc. [source]


    Expression of the LIM-homeodomain protein Isl1 in the developing and mature mouse retina

    THE JOURNAL OF COMPARATIVE NEUROLOGY, Issue 1 2007
    Yasser Elshatory
    Abstract The mammalian retina is comprised of six major neuronal cell types and is subdivided into more morphological and physiological subtypes. The transcriptional machinery underlying these subtype fate choices is largely unknown. The LIM-homeodomain protein, Isl1, plays an essential role in central nervous system (CNS) differentiation but its relationship to retinal neurogenesis remains unknown. We report here its dynamic spatiotemporal expression in the mouse retina. Among bipolar interneurons, Isl1 expression commences at postnatal day (P)5 and is later restricted to ON-bipolar cells. The intensity of Isl1 expression is found to segregate the pool of ON-bipolar cells into rod and ON-cone bipolar cells with higher expression in rod bipolar cells. As bipolar cell development proceeds from P5,10 the colocalization of Isl1 and the pan-bipolar cell marker Chx10 reveals the organization of ON-center bipolar cell nuclei to the upper portion of the inner nuclear layer. Further, whereas Isl1 is predominantly a ganglion cell marker prior to embryonic day (E)15.5, at E15.5 and later its expression in nonganglion cells expands. We demonstrate that these Isl1-positive, nonganglion cells acquire the expression of amacrine cell markers embryonically, likely representing nascent cholinergic amacrine cells. Taken together, Isl1 is expressed during the maturation of and is later maintained in retinal ganglion cells and subtypes of amacrine and bipolar cells where it may function in the maintenance of these cells into adulthood. J. Comp. Neurol. 503:182,197, 2007. © 2007 Wiley-Liss, Inc. [source]


    Synaptic localization of P2X7 receptors in the rat retina

    THE JOURNAL OF COMPARATIVE NEUROLOGY, Issue 1 2004
    Theresa Puthussery
    Abstract The distribution of P2X7 receptor (P2X7R) subunits was studied in the rat retina using a subunit-specific antiserum. Punctate immunofluorescence was observed in the inner and outer plexiform layers. Double labeling of P2X7 and the horizontal cell marker, calbindin, revealed extensive colocalization in the outer plexiform layer (OPL). Significant colocalization of P2X7R and kinesin, a marker of photoreceptor ribbons, was also observed, indicating that this receptor may be expressed at photoreceptor terminals. Furthermore, another band of P2X7R puncta was identified below the level of the photoreceptor terminals, adjacent to the inner nuclear layer (INL). This band of P2X7R puncta colocalized with the active-zone protein, bassoon, suggesting that "synapse-like" structures exist outside photoreceptor terminals. Preembedding immunoelectron microscopy demonstrated P2X7R labeling of photoreceptor terminals adjacent to ribbons. In addition, some horizontal cell dendrites and putative "desmosome-like" junctions below cone pedicles were labeled. In the inner plexiform layer (IPL), P2X7R puncta were observed surrounding terminals immunoreactive for protein kinase C-,, a marker of rod bipolar cells. Double labeling with bassoon in the IPL revealed extensive colocalization, indicating that P2X7R is likely to be found at conventional cell synapses. This finding was confirmed at the ultrastructural level: only processes presynaptic to rod bipolar cells were found to be labeled for the P2X7R, as well as other conventional synapses. These findings suggest that purines play a significant role in neurotransmission within the retina, and may modulate both photoreceptor and rod bipolar cell responses. J. Comp. Neurol. 472:13,23, 2004. © 2004 Wiley-Liss, Inc. [source]


    The Bmi1 polycomb gene as a target for therapies against retinal degeneration

    ACTA OPHTHALMOLOGICA, Issue 2009
    Y ARSENIJEVIC
    Purpose In several neurodegenerative diseases the reactivation of cell cycle proteins is a key event that precedes neuronal apoptosis. We asked whether a similar phenomenon occurs in Rd1 mice, a model of retinitis pigmentosa widely used to study photoreceptor (PR) loss. Methods We used different knockout mouse models to reveal whether proteins involved in the cell cycle regulation are responsible for photoreceptor loss in the Rd1 mouse. Results At P12, an early stage of the disease, Rd1 mice displayed an increased expression of CDK4 and CDK2 among PR nuclei. PRs also undergo DNA synthesis. At P12, the polycomb protein Bmi1 was expressed in virtually all the nuclei in the inner and outer nuclear layer of both wild-type (WT) and Rd1 mice. Bmi1 promotes cell cycle progression via the repression of tumor suppressor genes. We reasoned that Bmi1 deletion could impede the aberrant CDK reactivation that characterizes neuronal apoptosis and may therefore delay retinal degeneration. We compared the histology of WT, Rd1 and Rd1;Bmi1-/- and observed the presence of 7 rows of PRs in Rd1;Bmi1-/- mice at P33, while Rd1 littermates displayed a single scattered row of PRs. ERG recordings revealed the ability of Rd1:Bmi1-/- retinas to respond to light stimuli. Both DNA synthesis and CDK4 were strongly decreased in Rd1;Bmi1-/- mice, respectively by 70% and 50% as compared to Rd1 littermates. Conclusion In conclusion, our data show for the first time a mechanism of retina degeneration involving a reactivation of the cell cycle that precedes PR death in Rd1 mice and reveal that the partial inhibition of cell cycle re-entry strongly delays PR loss. [source]


    Quantification and characterization of GABA-ergic amacrine cells in the retina of GAD67-GFP knock-in mice

    ACTA OPHTHALMOLOGICA, Issue 4 2008
    Christian Albrecht May
    Abstract. Purpose:, Although the presence of ,-aminobutyrate acid (GABA) in amacrine cells and its co-localization with other neuronal substances is well known, there exists only little information about their quantitative distribution in the mouse eye. The aim of the present study was to characterize GABA-ergic amacrine cells in the retina of the recently introduced glutamate decarboxylase 67-green fluorescent protein (GAD67-GFP) knock-in mouse. Methods:, Whole mounts of the retina were prepared and the GFP-positive neurons quantified. Immunofluorescence staining was performed with antibodies against GABA, calbindin (CB), calretinin (CR), parvalbumin (PV), choline acetyl transferase (ChAT), tyrosine hydroxylase (TH), vesicular glutamate transporter (VGluT) 1, VGluT2 and VGluT3. Results:, Displaced GABA-ergic amacrine cells in the ganglion cell layer (GCL) showed a density of 1006 ± 170 cells/mm2. In the inner nuclear layer (INL), the density of amacrine cells was 8821 ± 448 cells/mm2 in the central region and 6825 ± 408 cells/mm2 in the peripheral region. GFP-positive amacrine cells co-localized with GABA (99%), CR (INL 18%, GCL 71.3%), CB (INL 6.3%), bNOS (INL 1%, GCL 4%), and ChAT (INL 17%, GCL 92.6%). No co-localization was seen with antibodies against PV, TH, and VGluT 1-3. Conclusions:, This study presents the first quantitative data concerning the co-localization of GABA-ergic neurons in the mouse retina with various neuronal markers. [source]


    Subunits of the epithelial sodium channel family are differentially expressed in the retina of mice with ocular hypertension

    JOURNAL OF NEUROCHEMISTRY, Issue 1 2005
    Frank M. Dyka
    Abstract Glaucoma is a prevalent cause of blindness, resulting in the apoptotic death of retinal ganglion cells and optic nerve degeneration. The disease is often associated with elevated intraocular pressure, however, molecular mechanisms involved in ganglion cell death are poorly understood. To identify proteins contributing to this pathological process, we analysed the retinal gene expression of DBA/2J mice that develop an elevated intraocular pressure by the age of 6 months with subsequent ganglion cell loss. In this study, we identified subunits of the epithelial sodium channel (ENaC) family that are specifically expressed under elevated intraocular pressure. Using reverse transcriptase polymerase chain reaction we observed a significant increase of ,-ENaC in the neuronal retina of DBA/2J mice when compared with control animals, while ,-ENaC and ,-ENaC were not detectable in this tissue. Specific immune sera to ENaC subunits showed up-regulation of ,-ENaC in synaptic and nuclear layers of the retina, and in the retinal pigment epithelium. Consistent with our polymerase chain reaction data, ,-ENaC was not detected by specific antibodies in the retina, while ,-ENaC was only present in the retinal pigment epithelium under ocular hypertension. Finally, the increase of ,-ENaC gene expression in the neuronal retina and the retinal pigment epithelium was not observed in other tissues of DBA/2J mice. Since the intraocular pressure is regulated by the transport of aqueous humour across epithelial structures of the eye that in turn is associated with ion flux, the specific up-regulation of ENaC proteins could serve as a protecting mechanism against elevated intraocular pressure. [source]


    Synaptic localization of neuroligin 2 in the rodent retina: Comparative study with the dystroglycan-containing complex

    JOURNAL OF NEUROSCIENCE RESEARCH, Issue 4 2010
    Leona Lui
    Abstract Several recent studies have shown that neuroligin 2 (NL2), a component of the cell adhesion neurexins,neuroligins complex, is localized postsynaptically at hippocampal and other inhibitory synapses throughout the brain. Other studies have shown that components of the dystroglycan complex are also localized at a subset of inhibitory synapses and are coexpressed with NL2 in brain. These data prompted us to undertake a comparative study between the localization of NL2 and the dystroglycan complex in the rodent retina. First, we determined that NL2 mRNA is expressed both in the inner and in the outer nuclear layers. Second, we found that NL2 is localized both in the inner and in the outer synaptic plexiform layers. In the latter, the horseshoe-shaped pattern of NL2 and its extensive colocalization with RIM2, a component of the presynaptic active zone at ribbon synapses, argue that NL2 is localized presynaptically at photoreceptor terminals. Third, comparison of NL2 and the dystroglycan complex distribution patterns reveals that, despite their coexpression in the outer plexiform layer, they are spatially segregated within distinct domains of the photoreceptor terminals, where NL2 is selectively associated with the active zone and the dystroglycan complex is distally distributed in the lateral regions. Finally, we report that the dystroglycan deficiency in the mdx3cv mouse does not alter NL2 localization in the outer plexiform layer. These data show that the NL2- and dystroglycan-containing complexes are differentially localized in the presynaptic photoreceptor terminals and suggest that they may serve distinct functions in retina. © 2009 Wiley-Liss, Inc. [source]


    Ocular phenotype in a mouse gene knockout model for infantile neuronal ceroid lipofuscinosis

    JOURNAL OF NEUROSCIENCE RESEARCH, Issue 5 2006
    Bo Lei
    Abstract Mutations in the human protein palmitoyl thioesterase-1 (PPT-1) gene result in an autosomal recessive neurodegenerative disorder designated neuronal ceroid lipofuscinosis (NCL), type CLN1, or infantile NCL. Among the symptoms of the CLN1 disease are accumulation of autofluorescent lysosomal storage bodies in neurons and other cell types, seizures, motor and cognitive decline, blindness, and premature death. Development of an effective therapy for this disorder will be greatly assisted by the availability of suitable animal models. A mouse PPT-1 gene knockout model has recently been generated. Studies were performed to determine whether the mouse model exhibits ocular features of the human CLN1 disorder. A progressive accumulation of autofluorescent storage material in all layers of the retina was observed in the PPT-1 knockout mice. Accompanying the storage body accumulation was a modest loss of cells with nuclei in the outer and inner nuclear layers. As indicated by electroretinogram (ERG) responses, retinal function was only mildly impaired at 4 months of age but was severely impaired by 8 months, despite only modest changes in retinal morphology. The pupillary light reflex (PLR), on the other hand, was exaggerated in the knockout mice. The apparent anomaly between the ERG and the PLR findings suggests that disease-related PLR changes may be due to changes in extraocular signal processing. The pronounced ocular phenotype in the PPT-1 knockout mice makes these animals a good model for testing therapeutic interventions for treatment of the human CLN1 disorder. © 2006 Wiley-Liss, Inc. [source]


    6-Formylpterin protects retinal neurons from transient ischemia,reperfusion injury in rats: A morphological and immunohistochemical study

    NEUROPATHOLOGY, Issue 3 2003
    Taisaku Funakoshi
    Neuroprotective effects of 6-formylpterin (6FP) on transient retinal ischemia,reperfusion injury were evaluated in rats by means of counting the number of retinal ganglion cells, measuring the thicknesses of the inner plexiform and inner nuclear layers, and by immunohistochemical detection of apoptotic cells in the retina. Sixty-one Sprague,Dawley rats (12 weeks, male, 295,330 g) were subjected to transient retinal ischemia,reperfusion by elevated intra-ocular pressure (80 mmHg for 60 min). Intraperitoneal injection of 6FP (3.8 mg/kg) was performed before or after ischemia. The retina was histologically better preserved in rats with 6FP treatment than without 6FP treatment. 6FP showed more strong neuroprotective effects when it was administered before ischemia. The number of single-stranded DNA-positive cells in the retina also decreased remarkably in rats with 6FP treatment, especially when administered before ischemia. These results suggest that 6FP protects retinal neurons from transient ischemia,reperfusion injury, at least in part by inhibiting apoptotic cell death. [source]


    Morphology and mosaics of melanopsin-expressing retinal ganglion cell types in mice

    THE JOURNAL OF COMPARATIVE NEUROLOGY, Issue 13 2010
    David M. Berson
    Abstract Melanopsin is the photopigment of intrinsically photosensitive retinal ganglion cells (ipRGCs). Melanopsin immunoreactivity reveals two dendritic plexuses within the inner plexiform layer (IPL) and morphologically heterogeneous retinal ganglion cells. Using enhanced immunohistochemistry, we provide a fuller description of murine cell types expressing melanopsin, their contribution to the plexuses of melanopsin dendrites, and mosaics formed by each type. M1 cells, corresponding to the originally described ganglion-cell photoreceptors, occupy the ganglion cell or inner nuclear layers. Their large, sparsely branched arbors (mean diameter 275 ,m) monostratify at the outer limit of the OFF sublayer. M2 cells also have large, monostratified dendritic arbors (mean diameter 310 ,m), but ramify in the inner third of the IPL, within the ON sublayer. There are ,900 M1 cells and 800 M2 cells per retina; each type comprises roughly 1,2% of all ganglion cells. The cell bodies of M1 cells are slightly smaller than those of M2 cells (mean diameters: 13 ,m for M1, 15 ,m for M2). Dendritic field overlap is extensive within each type (coverage factors ,3.8 for M1 and 2.5 for M2 cells). Rare bistratified cells deploy terminal dendrites within both melanopsin-immunoreactive plexuses. Because these are too sparsely distributed to permit complete retinal tiling, they lack a key feature of true ganglion cell types and may be anomalous hybrids of the M1 and M2 types. Finally, we observed weak melanopsin immunoreactivity in other ganglion cells, mostly with large somata, that may constitute one or more additional types of melanopsin-expressing cells. J. Comp. Neurol. 518:2405,2422, 2010. © 2010 Wiley-Liss, Inc. [source]


    Morphology and mosaics of melanopsin-expressing retinal ganglion cell types in mice,

    THE JOURNAL OF COMPARATIVE NEUROLOGY, Issue 13 2010
    David M. Berson
    Abstract Melanopsin is the photopigment of intrinsically photosensitive retinal ganglion cells (ipRGCs). Melanopsin immunoreactivity reveals two dendritic plexuses within the inner plexiform layer (IPL) and morphologically heterogeneous retinal ganglion cells. Using enhanced immunohistochemistry, we provide a fuller description of murine cell types expressing melanopsin, their contribution to the plexuses of melanopsin dendrites, and mosaics formed by each type. M1 cells, corresponding to the originally described ganglion-cell photoreceptors, occupy the ganglion cell or inner nuclear layers. Their large, sparsely branched arbors (mean diameter 275 ,m) monostratify at the outer limit of the OFF sublayer. M2 cells also have large, monostratified dendritic arbors (mean diameter 310 ,m), but ramify in the inner third of the IPL, within the ON sublayer. There are ,900 M1 cells and 800 M2 cells per retina; each type comprises roughly 1,2% of all ganglion cells. The cell bodies of M1 cells are slightly smaller than those of M2 cells (mean diameters: 13 ,m for M1, 15 ,m for M2). Dendritic field overlap is extensive within each type (coverage factors ,3.8 for M1 and 4.6 for M2 cells). Rare bistratified cells deploy terminal dendrites within both melanopsin-immunoreactive plexuses. Because these are too sparsely distributed to permit complete retinal tiling, they lack a key feature of true ganglion cell types and may be anomalous hybrids of the M1 and M2 types. Finally, we observed weak melanopsin immunoreactivity in other ganglion cells, mostly with large somata, that may constitute one or more additional types of melanopsin-expressing cells. J. Comp. Neurol. 518:2405,2422, 2010. © 2010 Wiley-Liss, Inc. [source]


    The distribution of neuroglobin in mouse eye

    ACTA OPHTHALMOLOGICA, Issue 2009
    Y YOU
    Purpose To determine the distribution of neuroglobin (Ngb) in mouse eye. Ngb is predominantly expressed in the nervous system,and at particularly high levels in the retina. Ngb may serve as a reactive oxygen scavenger and may protect the tissue of eye from ischemia/hypoxia injuries. However,the distribution of Ngb in the eye is still controversial. Methods Two polyclonal antibodies against Ngb were used in this immunohistochemical study, both of which were raised in rabbits. One of these two antibodies was generated against the whole recombinant protein of mouse Ngb and the other was generated against amino acid positions 55-70 of mouse and human Ngb. The expression of Ngb was analyzed with light microscopy on tissue sections. Results These two antibodies showed comparable results. Ngb was expressed in the layers of the retina, including the ganglion cell layer, inner and outer nuclear layers, inner and outer plexiform layers, the inner segments of the photoreceptors and the retinal pigment epithelium. Ngb was also detected in other structures of the eye, including the epithelium and endothelium of cornea,the stroma of iris,the ciliary body, the lens epithelium, and the sclera. However, Ngb was not expressed in the corneal stroma, the lens capsule, the lamellar fibers of lens, the pigment epithelium of ciliary body or the pigment layer of iris. Conclusion Ngb was found widely distributed in mouse eye. This finding can be explained by the fact that most of the structures of the eye originated from neural crest/neural ectoderm. Future experiments will focus on the distribution of Ngb at the mRNA level (in situ hybridization),and the quantitative expression levels at baseline and after hypoxic/ischemic challenge. [source]