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Results for “Retinal Horizontal Cells”

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At least 271 records · Page 15Linked to original sources

PubMed1998

McAB 300 antibody against calbindin D-28K is a glial marker in the teleost brain.

The monoclonal antibody McAB 300 against calbindin D-28 k demonstrated an immunostaining pattern in the teleost brain completely different to those obtained in other classes of vertebrates, or after using in the teleost brain other monoclonal and polyclonal antibodies raised against the same protein. Although calbindin D-28k is considered a neuronal marker, McAB 300 specifically stained glial cells throughout the brains of teleosts, with the only exception of some retinal amacrine and horizontal cells.

Animals↗

PubMed1978

Topography of horizontal cells in the retina of the domestic cat.

Neurofibrillar methods stain a class of horizontal cells in the cat retina which are shown to be identical with the A-type horizontal cell of Golgi-staining. Thus all of the A-type cells of a single retina can be observed. On this basis the changes in density and dendritic field size of A-type horizontal cells with respect to retinal eccentricity were measured. The decrease in density from centre to periphery is balanced by a corresponding increase in size of the dendritic field. Consequently each retinal point--independent of retinal position--is covered by the dendritic fields of three of four A-type horizontal cells. The nuclei and nucleoli of B-type horizontal cells could also be recognized in neurofibrillar-stained material and thus their distribution was determined. The density ratio B-type: A-type is 2.8 +/- 0.4 and does not vary much from the centre to the periphery of the retina. Each retinal point is also covered by four B-type horizontal cells. Thus a single cone can contact a maximum of eight horizontal cells. The rate of density decrease from centre to periphery is closely similar in cones and horizontal cells but greater in ganglion cells.

Animals↗

PubMed1994

Modulation of gap-junction channel gating at zebrafish retinal electrical synapses.

1. Transmission at electrical synapses is modulated by a variety of physiological signals, and this modulation is a potentially general mechanism for regulating signal integration in neural circuits and networks. In the outer plexiform layer of the retina, modulation of horizontal-cell electrical coupling by dopamine alters the extent of spatial integration in the horizontal-cell network. By analyzing the activity of individual gap-junction channels in low-conductance electrical synapses of zebrafish retinal horizontal cells, we have defined the properties of these synaptic ion channels and characterized the functional changes in them during modulation of horizontal-cell electrical synapses. 2. Zebrafish horizontal-cell gap-junction channels have a unitary conductance of 50-60 pS and exhibit open times of several tens of milliseconds. The kinetic process of channel closure is best described by the sum of two rate constants. 3. Dopamine, and its agonist, (+/-)-6,7-dihydroxy-2-amino-tetralin (ADTN), modulates electrical synaptic transmission between horizontal cells predominantly by affecting channel-gating kinetics. These agents reduced the open probability of gap-junction channels two- to threefold by reducing both the duration and frequency of channel openings. Both time constants for channel open duration were reduced, whereas the duration of shut periods was increased. Similar changes in open-time kinetics were observed in power spectra of higher conductance gap junctions. 4. These results provide a description of rapid electrical synaptic modulation at the single channel level. The description should be useful in understanding the mechanisms of plasticity at these synapses throughout the vertebrate central nervous system.

Animals↗

PubMed1998

GABA as a developmental signal in the inner retina and optic nerve.

Gamma-aminobutyric acid (GABA) acts as an inhibitory neurotransmitter in the mature vertebrate retina, where it is localized predominantly in amacrine cells, and to a lesser extent in other cell types. During development, GABA is expressed transiently in additional cells, including retinal ganglion cells and horizontal cells. Elements of the GABA system, including GABA uptake and release mechanisms and GABA receptors, are also expressed early in retinal development, well in advance of the onset of visual function. The GABA transporter is a major component of the GABA system in the mature retina, and is most likely responsible for GABA release early in development, prior to the establishment of vesicular synaptic transmission. GABA, produced by amacrine cells and retinal ganglion cells, may serve a developmental role in the establishment of circuitry in the retinal inner plexiform layer and may also be involved in the formation of appropriate central connections by retinal ganglion cell axons.

Animals↗

PubMed2004

Possible mechanism of flicking-induced short-term plasticity in retinal cone-LHC synapse: a computational study.

In retinal cone-HC synapse, it has been found that repetitive stimulation could induce postsynaptic short-term responsiveness enhancement. However, the detailed mechanism underlying this short-term plasticity in the retinal graded neurons remains unclear. In this study, based on an ion-channel model described using Hodgkin--Huxley equations, the possible mechanism of repetitive-stimulation-induced short-term plasticity in the synapse between retinal cones and horizontal cells was investigated. The computational simulation results, together with evidence from experimental observations, suggest that the short-term modification of signal transmission between the retinal graded neurons is likely to be attributed to the regulatory effects that calcium-dependent process exerts on the single-channel properties of the postsynaptic AMPA receptors.

Animals↗

PubMed2004

Nitric oxide modulates the transfer function between cones and horizontal cells during changing conditions of ambient illumination.

It has been suggested that nitric oxide (NO) serves as a retinal neuromodulator, adjusting retinal function to changing conditions of adaptation. We tested this hypothesis in the intact turtle retina by recording the photoresponses of L-cones and L1-horizontal cells, while changing retinal NO level and background illumination. Raising the retinal level of NO, by adding an NO donor (sodium nitroprusside) or the precursor for NO synthesis (L-arginine), induced response augmentation in L-cones and L1-horizontal cells. Lowering retinal level of NO by adding L-NAME, an inhibitor of NO synthesis, reduced the amplitudes of the photoresponses in these retinal neurons. The transfer function between L-cones and L1-horizontal cells, constructed from the photoresponses of these cells, was modified by NO and by background lights. The nonlinear transfer function, characteristic of the dark-adapted retina, became linear and of low gain when the retinal NO level was increased or by increasing the level of ambient illumination. In contrast, inhibiting NO synthesis in the light-adapted retina induced nonlinearity in the cone-to-horizontal cell transfer function similar to that seen in the dark-adapted state. NADPH diaphorase histochemistry, conducted on isolated retinal cells, demonstrated activity in cone inner segments and distal process of Müller cells. These findings support the hypothesis that NO synthesis in the distal turtle retina is triggered by background illumination, and that NO acts to adjust the modes of visual information processing in the outer plexiform layer to the conditions required during continuous background illumination.

Adaptation, Physiological↗

PubMed1997

Subsets of retinal progenitors display temporally regulated and distinct biases in the fates of their progeny.

Cell fate determination in the developing vertebrate retina is characterized by the sequential generation of seven classes of cells by multipotent progenitor cells. Despite this order of genesis, more than one cell type is generated at any time; for example, in the rat, several cell types are born during the prenatal period, while others are born postnatally. In order to examine whether there are classes of progenitor cells with distinct developmental properties contributing to this developmental progression, we examined antigen expression in progenitor cells during rat retinal development. Two markers of amacrine and horizontal cells, the VC1.1 epitope and syntaxin, were found to be expressed on a subset of progenitors in a temporally regulated manner that closely paralleled the birthdays of these cell types. In order to investigate which cell types were produced by the progenitors expressing these markers, fluorescent latex microspheres covalently coupled to VC1.1 antibodies were used to indelibly label VC1.1+ progenitor cells and their progeny. Early in retinal development, VC1.1+ progenitors generated a high percentage of amacrine and horizontal cells, but no cone photoreceptors. During this same period, a comparable number of cone photoreceptors were generated by VC1.1- progenitors. In the late embryonic and early postnatal period, VC1.1+ progenitors continued to generate predominantly amacrine cells, but also gave rise to an increasing number of rod photoreceptors. These findings demonstrate that expression of these two markers by progenitors is highly correlated with a bias towards the production of amacrine and horizontal cells. The fact that subsets of progenitors with temporally regulated and distinct biases are intermingled within the retinal neuroepithelium provides a basis for understanding how different cell types are generated both simultaneously and in a particular order by multipotent progenitors during retinal development.

Aging↗

PubMed1991

Many diverse types of retinal neurons show tracer coupling when injected with biocytin or Neurobiotin.

This study demonstrates that the junctional connections between rod-signal interneurons in mammalian retina can be visualized by tracer coupling, following intracellular injection of the biotinylated compounds, biocytin and Neurobiotin. In addition, many other types of retinal neurons -including B-type horizontal cells and several types of retinal ganglion cells-show specific patterns of tracer coupling, usually to cells of the same neuronal type but occasionally to cells of other neuronal classes. These findings suggest that electronic transmission occurs commonly throughout the retina and, consequently, diverse types of retinal neurons may form functional networks of coupled cells.

Animals↗

PubMedDate not supplied

Horizontal cells in the retina of a diurnal rodent, the agouti ( Dasyprocta aguti ).

The morphology and distribution of normally placed and displaced A horizontal cells were studied in the retina of a diurnal hystricomorph rodent, the agouti Dasyprocta aguti. Cells were labeled with anti-calbindin immunocytochemistry. Dendritic-field size reaches a minimum in the visual streak, of about 9,000 microm(2), and increases toward the retinal periphery both in the dorsal and ventral regions. There is a dorsoventral asymmetry, with dorsal cells being larger than ventral cells at equal distances from the streak. The peak value for cell density of 281 +/- 28 cells/mm(2) occurs in the center of the visual streak, decreasing toward the dorsal and ventral retinal periphery, paralleling the increase in dendritic-field size. Along the visual streak, the decline in cell density is less pronounced, remaining between 100-200 cells/mm(2) in the temporal and nasal periphery. Displaced horizontal cells are rare and occur in the retinal periphery. They tend to be smaller than normally placed horizontal cells in the ventral region, whilst no systematic difference was observed between the two cell groups in the dorsal region. Mosaic regularity was studied using nearest-neighbor analysis and the Ripley function. When mosaic regularity was determined removing the displaced horizontal cells, there was a slight increase in the conformity ratio, but the bivariate Ripley function indicated some repulsive dependence between the two mosaics. Both results were near the level of significance. A similar analysis performed in the capybara retina, a closely related hystricomorph rodent bearing a higher density of displaced horizontal cells than found in the agouti, suggested spatial independence between the two mosaics, normally placed versus displaced horizontal cells.

Algorithms↗

PubMed2004

Newborn horizontal cells migrate bi-directionally across the neuroepithelium during retinal development.

Cell migration plays an important role during the development of the retina. In this work we have studied the migration of newborn horizontal cells in avian embryonic retina. Using the pattern of the early expressed transcription factors Lim1 and Prox1 we have shown that horizontal cells migrate bi-directionally from their site of birth, close to the ventricular side, to the adjacent (vitreal) side of the neuroepithelium, where they align just next to the prospective ganglion cell layer before migrating back again to their final laminar position in the external part of the inner nuclear layer. The migration occurs between Hamburger and Hamilton stages 24 and 33, which is equivalent to embryonic day 4.5 and 8. Between stages 26 and 30 the horizontal cells reside close to the ganglion cell layer and intra ocular injections of a cytochalasin D, an actin polymerisation blocker that inhibit migration, at stage 29 interfered with the migration of the horizontal cells to their final destination. Furthermore, using biolistic gene transfer with a green fluorescence protein expression vector of retinal slices we were able to record ventricle-directed migration by time-lapse microscopy. Combining biolistics with immunohistochemistry we showed that transfected cells, which have also been translocated in a ventricular direction were positive for the horizontal cell markers Lim1 and Prox1. The alternative path of migration that is described in this work differs from the generally accepted one for horizontal cells and this knowledge will influence the view of how the molecular determination of horizontal cells is specified.

Animals↗

PubMedDate not supplied

Topographies of retinal cone photoreceptors in two Australian marsupials.

Microspectrophotometry indicates the presence of at least three cone visual pigments in two Australian marsupials, the fat-tailed dunnart (Sminthopsis crassicaudata) and honey possum (Tarsipes rostratus). Here we have examined the distribution of cone types using antisera, JH455 and JH492, that recognize short-wavelength-sensitive (SWS) and medium-to-long-wavelength-sensitive (M/LWS) cone opsins, respectively. SWS cones were concentrated in dorso-temporal retina in the dunnart with a shallow decreasing gradient extending to the periphery (2300-1500/mm2). In the honey possum, SWS cones showed a uniform distribution (2700/mm2), except for a slight increase in a narrow peripheral band (3100/mm2). In both species, M/LWS cones dominated and their distributions were similar to those of retinal ganglion cells: a horizontal streak in the dunnart (31,000-21,000/mm2) and a shallow mid-ventral to peripheral gradient in the honey possum (37,000-26,000/mm2). A low number of cones remained unlabeled when the antisera were combined revealing further minority cone population(s). We discuss cone distributions in relation to visual capabilities and requirements of the species.

Animals↗

PubMed2005

Changes in retinal neuronal populations in the DBA/2J mouse.

DBA/2J (D2) mice develop a form of progressive pigmentary glaucoma with increasing age. We have compared retinal cell populations of D2 mice with those in control C57BL/6J mice to provide information on retinal histopathology in the D2 mouse. The D2 mouse retina is characterized by a reduction in retinal thickness caused mainly by a thinning of the inner retinal layers. Immunocytochemical staining for specific inner retinal neuronal markers, viz., calbindin for horizontal cells; protein kinase C (PKC) and recoverin for bipolar cells, glycine, gamma-aminobutyric acid (GABA), choline acetyltransferase (ChAT), and nitric oxide synthase (NOS) for amacrine cells, and osteopontin (OPN) for ganglion cells, was performed to detect preferentially affected neurons in the D2 mouse retina. Calbindin, PKC, and recoverin immunoreactivities were not significantly altered. Amacrine cells immunoreactive for GABA, ChAT, and OPN were markedly decreased in number, whereas NOS-immunoreactive amacrine cells increased in number. However, no changes were observed in the population of glycine-immunoreactive amacrine cells. These findings indicate a significant loss of retinal ganglion and some amacrine cells, whereas glycinergic amacrine cells, horizontal, and bipolar cells are almost unaffected in the D2 mouse. The reduction in amacrine cells appears to be attributable to a loss of GABAergic and particularly cholinergic amacrine cells. The increase in nitrergic neurons with the consequent increase in NOS and NO may be important in the changes in the retinal organization that lead to glaucomain D2 mice. Thus, the D2 mouse retina represents a useful model for studying the pathogenesis of glaucoma and mechanisms of retinal neuronal death and for evaluating neuroprotection strategies.

Amacrine Cells↗

PubMed1997

Identification and localization of an immunoreactive AMPA-type glutamate receptor subunit (GluR4) with respect to identified photoreceptor synapses in the outer plexiform layer of goldfish retina.

L-glutamate, the main excitatory synaptic transmitter in the retina, is released from photoreceptors and evokes responses in second-order retinal neurons (horizontal, bipolar cells) which utilize both ionotropic and metabotropic types of glutamate receptors. In the present study, to elucidate the functional roles of glutamate receptors in synaptic transmission, we have identified a specific ionotropic receptor subunit (GluR4) and determined its localization with respect to photoreceptor cells in the outer plexiform layer of the goldfish retina by light and pre-embedding electron-microscopical immunocytochemistry. We screened antisera to mammalian AMPA (alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionate)-preferring ionotropic glutamate receptors (GluR 1-4) of goldfish retina by light- and electron-microscopical immunocytochemistry. Only immunoreactive (IR) GluR4 was found in discrete clusters in the outer plexiform layer. The cones contacted in this manner were identified as long-wavelength ("red") and intermediate-wavelength ("green") cones, which were strongly immunoreactive to monoclonal antibody FRet 43 and antisera to goldfish red and green-cone opsins; and short-wavelength ("blue") cones, which were weakly immunoreactive to FRet 43 but strongly immunoreactive with antiserum to blue-cone opsin. Immunoblots of goldfish retinal homogenate with anti-GluR4 revealed a single protein at M(r) = 110 kDa. Preadsorption of GluR4 antiserum with either the immunizing rat peptide, or its goldfish homolog, reduced or abolished staining in retinal sections and blots. Therefore, we have detected and localized genuine goldfish GluR4 in the outer plexiform layer of the goldfish retina. We characterized contacts between photoreceptor cells and GluR4-IR second-order neurons in the electron microscope. IR-GluR4 was localized to invaginating central dendrites of triads in ribbon synapses of red cones, semi-invaginating dendrites in other cones and rods, and dendrites making wide-cleft basal junctions in rods and cones; the GluR4-IR structures are best identified as dendrites of OFF-bipolar cells. The results of our studies indicate that in goldfish retina GluR4-expressing neurons are postsynaptic to all types of photoreceptors and that transmission from photoreceptors to OFF-bipolars is mediated at least in part by AMPA-sensitive receptors containing GluR4 subunits.

Amino Acid Sequence↗

PubMed1993

Characterization of the glutamate transporter in retinal cones of the tiger salamander.

L-Glutamate elicits an inwardly rectifying current at hyperpolarized potentials in isolated retinal cones of the tiger salamander, as measured under whole-cell patch clamp. Evidence presented in this article supports the notion that cones possess a high-affinity glutamate transporter. This glutamate-elicited current shows no desensitization over a period of several minutes, and has an affinity (Km) of 10 microM. The inward current is mimicked by the amino acids L-aspartate, D-aspartate, L-cysteate, and to a lesser extent D-glutamate. It is neither blocked by the glutamate receptor antagonists kynurenic acid (1 mM), 6-cyano-7-nitroquinoxaline-2,3-dione (100 microM), or 2-amino-5-phosphonovalerate (100 microM), nor elicited by the glutamate receptor agonists (100 microM each) kainate, quisqualate, NMDA, or 2-amino-4-phosphonobutyrate. The glutamate-elicited current was reduced by the glutamate transport blockers dihydrokainate (DHKA), DL-threo-beta-hydroxyaspartate (beta HA), and L-trans-pyrrolidine-2,4-dicarboxylic acid. When glutamate was present on both sides of the membrane, the blockers reduced both uptake and release; the blocker-sensitive current as a function of membrane potential represents the transport current-voltage relation (I-V), and the reversal potential of the I-V represents the transporter equilibrium potential. This potential was a function of the equilibrium potential for glutamate. DHKA and beta HA depolarized horizontal cells in a retinal slice, and abolished their light responses, suggesting that in the absence of glutamate transport, glutamate concentrations in the cleft rise to a level that saturates the postsynaptic receptors. The high capacity of the cone glutamate transporter is well suited for the rapid removal of glutamate from the synaptic cleft required for the signaling of a light onset to postsynaptic cells.

Ambystoma↗

PubMed2003

Evolution of eyes and photoreceptor cell types.

The evolution of the eye is a matter of debate ever since Darwin's Origin of Species. While morphological comparisons of eye anatomy and photoreceptor cell types led to the view that animal eyes evolved multiple times independently, the molecular conservation of the pax6 eye-specifying cascade has indicated the contrary - that animal eyes evolved from a common, simple precursor, the proto-eye. Morphological and molecular comparative approaches are combined here in a novel Evo-Devo approach, the molecular comparison of cell types ("comparative molecular cell biology"). In the eye, the various types of photoreceptor cells, as well as pigment and lens cells, each require distinct combinations of specifying transcription factors that control their particular differentiation programmes, such as opsin expression in photoreceptors, specific neurotransmitter metabolism, or axonal outgrowth. Comparing the molecular combinatorial codes of cell types of animal extant eyes, their evolutionary histories can be reconstructed. This is exemplified here on the evolution of ciliary and rhabdomeric photoreceptor cells in bilaterian eyes and on the evolution of cell type diversity in the vertebrate retina. I propose that the retinal ganglion, amacrine and horizontal cells are evolutionary sister cell types that evolved from a common rhabdomeric photoreceptor cell precursor.

Amacrine Cells↗

PubMed1984

Regular orientation of horizontal cells in the river lamprey retina.

In isolated retinas of the river lamprey (Lampetra japonica), two types (fast and slow) of light-induced responses (S-potentials) were recorded from two distinct classes of axon-bearing horizontal cells. After the spectral responses of recording cells were examined, a fluorescent dye Lucifer yellow CH (LY) was ionophoretically injected into individual cells. Such a cellular marking was made for 15-25 points per retina successively in time and in space. Then the retinas were processed as flatmounts for fluorescence microscopic observation. Horizontal cells marked with LY were correlated with the recordings and mapped in the retinal field. Both classes of horizontal cells were found to be regularly arranged in space around the optic disc; the long axes of somata and axonal processes are oriented in parallel with the latitude line of the eyeball through the optic disc.

Animals↗

PubMed1993

A new type of interplexiform cell in the goldfish retina is PNMT-immunoreactive.

A new cell type immunoreactive for phenylethanolamine N-methyltransferase, the synthesizing enzyme for epinephrine, has been identified in the goldfish retina. The somata of the immunoreactive cells were located in the proximal inner nuclear layer and immunoreactive processes were located in both the inner and outer plexiform layers, suggesting that this cell may be an interplexiform cell. Confocal microscopy was used to establish that the putative adrenergic neurites in the outer plexiform layer were located between the somata of horizontal cells and photoreceptor cell synaptic terminals. Intracellular recordings from horizontal cells demonstrated that epinephrine had an effect on horizontal cells, but that the action of epinephrine was consistent with an effect on dopamine receptors, rather than adrenergic receptors. The function of the putative 'I3' interplexiform cell therefore remains unclear, possibly modulating horizontal cell function with a transmitter other than epinephrine or affecting photoreceptors or the retinal pigment epithelium rather than horizontal cells.

Animals↗

PubMedDate not supplied

Coexistence of neurofilaments and vimentin in a neurone of adult mouse retina.

Different classes of intermediate filaments are restricted to particular cell types. For example, neurofilaments are found only in neurones, whereas filaments that contain the protein vimentin, which were found in some cells of mesenchymal origin and some forms of glia, are thought to be absent from mature neurones, and present only transiently in early embryonic neurones. However, evidence is presented here of an exception to that rule in the outer plexiform layer of the mouse retina. Double-labelling with antibodies to neurofilaments and vimentin showed that both types of intermediate filaments coexisted in the axonless horizontal cell of that retinal layer, recalling the previous notion that these cells are glial or intermediate between neuronal and glial (reviewed in ref. 10).

Animals↗