AMPA-selective glutamate receptor subunits GluR2 and GluR4 in the cat retina: An immunocytochemical study

1999 ◽  
Vol 16 (6) ◽  
pp. 1105-1114 ◽  
Author(s):  
PU QIN ◽  
ROBERTA G. POURCHO

AMPA-selective glutamate receptors play a major role in glutamatergic neurotransmission in the retina and are expressed in a variety of neuronal subpopulations. In the present study, immunocytochemical techniques were used to visualize the distribution of GluR2 and GluR4 subunits in the cat retina. Results were compared with previous localizations of GluR1 and GluR2/3. Staining for GluR2 was limited to a small number of amacrine and ganglion cells whereas GluR4 staining was present in A-type horizontal cells, many amacrine cells including type AII amacrine cells, and the majority of the cells in the ganglion cell layer. Analysis of synaptic relationships in the outer plexiform layer showed the GluR4 subunit to be concentrated at the contacts of cone photoreceptors with A-horizontal cells. In the inner plexiform layer, both GluR2 and GluR4 were postsynaptic to cone bipolar cells at dyad contacts although GluR2 staining was limited to one of the postsynaptic elements whereas GluR4 immunoreactivity was often seen in both postsynaptic elements. Unlike GluR2, GluR4 was also postsynaptic to rod bipolar cells where it could be visualized in processes of AII amacrine cells. The data indicate that GluR3 and GluR4 subunits are colocalized in a number of cell types including A-type horizontal cells, AII amacrine cells, and alpha ganglion cells, but whether they are combined in the same multimeric receptors remains to be determined.

1994 ◽  
Vol 11 (2) ◽  
pp. 253-260 ◽  
Author(s):  
Norma Lake

AbstractThe content of taurine and the immunocytochemical localization of taurine and γ-aminobutyric acid (GABA) in the rat retina during postnatal development are described. The rat retina is immature at birth; about two-thirds of the cells are undifferentiated neuroblasts, and the taurine content per retina is approximately one-seventh of the adult value. Shortly after weaning the adult morphology and taurine content are attained. Expression of taurine immunoreactivity (taurine-IR) accompanies differentiation; in some cell types (ganglion and horizontal cells) this expression is transient, while in others (photoreceptors, bipolar, and a subpopulation of amacrine cells) it persists into the adult state. At birth, taurine-IR is localized mainly in cells in the position of ganglion cells, especially in their axons within the nerve fiber layer. This reactivity is soon lost from the somata, and disappears from the axons by 10 days of age. At 2 days of age, taurine-IR appeared additionally in somata of amacrine cells flanking the forerunner of the inner plexiform layer, and in growth cone-like processes of photoreceptors. At day 6, taurine-IR was marked in photoreceptor cell inner and outer segments, and in horizontal cells and their lateral processes. Taurine-IR was lost from horizontal cells and most amacrine cells around day 10, and appeared in bipolar cells, where it remained, with that in photoreceptors, into adulthood. Particularly striking was taurine-IR in large synaptic terminal-like processes close to the ganglion cell layer which were first seen around day 16. GABA immunoreactivity was never seen in photoreceptor or bipolar cells, was expressed transiently in horizontal cells at the same time as taurine-IR, but persisted in a subpopulation of amacrine cells and synaptic lamina in the inner plexiform layer and in some fine glial processes in the adult.


1985 ◽  
Vol 224 (1237) ◽  
pp. 475-488 ◽  

When cat retina is incubated in vitro with the fluorescent dye, 4',6- diamidino-2-phenyl-indole (DAPI), a uniform population of neurons is brightly labelled at the inner border of the inner nuclear layer. The dendritic morphology of the DAPI-labelled cells was defined by iontophoretic injection of Lucifer yellow under direct microscopic control: all the filled cells had the narrow-field bistratified morphology that is distinctive of the A ll amacrine cells previously described from Golgistained retinae. Although the A ll amacrines are principal interneurons in the rod-signal pathway, their density distribution does not follow the topography of the rod receptors, but peaks in the central area like the cone receptors and the ganglion cells. There are some 512000 A ll amacrines in the cat retina and their density ranges from 500 cells per square millimetre at the superior margin to 5300 cells per square millimetre in the centre (retinal area is 450 mm2). The isodensity contours are kite-shaped, particularly at intermediate densities, with a horizontal elongation towards nasal retina. The cell body size and the dendritic dimensions of A ll amacrines increase with decreasing cell density. The lobular dendrites in sublamina a of the inner plexiform layer span a restricted field of 16—45 pm diameter, while the arboreal dendrites in sublamina b form a varicose tree of 18—95 pm diameter. The dendritic field coverage of the lobular appendages is close to 1.0 (+ 0.2) at all eccentricities whereas the coverage of the arboreal dendrites doubles within the first 1.5 mm and then remains constant at 3.8 ( + 0.7) throughout the periphery.


1991 ◽  
Vol 7 (6) ◽  
pp. 611-618 ◽  
Author(s):  
Roberta G. Pourcho ◽  
Michael T. Owczarzak

AbstractImmunocytochemical techniques were used to localize strychnine-sensitive glycine receptors in cat retina. Light microscopy showed staining in processes ramifying throughout the inner plexiform layer and in cell bodies of both amacrine and ganglion cells. At the electron-microscopic level, receptor immunoreactivity was seen to be clustered at sites postsynaptic to amacrine cells. In contrast, bipolar cells were neither presynaptic nor postsynaptic elements at sites of glycine receptor staining. Double-label studies verified the presence of glycine immunoreactivity in amacrine terminals presynaptic to glycine receptors. These findings support a role for glycine as an inhibitory neurotransmitter in amacrine cells.


1994 ◽  
Vol 11 (6) ◽  
pp. 1193-1203 ◽  
Author(s):  
Chen-Yu Yang ◽  
Stephen Yazulla

AbstractThe presence of inhibitory bipolar cells in salamander retina was investigated by a comparative analysis of the distribution of glutamate- and GABA-immunoreactivities (GLU-IR; GABA-IR) using a postembedding immunocytochemical method. GLU-IR was found in virtually all photoreceptors, bipolar cells and ganglion cells, neuronal elements that transfer information vertically through the retina. GLU-IR also was found in numerous amacrine cells in the mid and proximal inner nuclear layer as well as in the cytoplasm of horizontal cells, while the nucleus of horizontal cells was either lightly labeled or not labeled at all. GLU-IR was found in the outer plexiform layer and intensely in the inner plexiform layer, in which there was no apparent sublamination. Forty-seven percent of Type IB bipolar cells in the distal inner nuclear layer and 13% of the displaced bipolar cells were GABA-IR. All bipolar cells were also GLU-IR, indicating that GABA-IR bipolar cells were a subset of GLU-IR bipolar cells rather than a separate population. About 12% of the Type IB bipolar cells were moderately GABA-IR and likely comprised a GABAergic subtype. GLU-IR levels in the presumed GABAergic bipolar cells were higher than in other purely GLU-IR bipolar cells suggesting that these GABA-IR bipolar cells are glutamatergic as well. All of the displaced bipolar cells were only lightly GABA-IR, indicating that displaced bipolar cells comprise a more homogeneous class of glutamatergic cell than orthotopic bipolar cells. GAD-IR co-localized with GABA-IR in orthotopic but not displaced bipolar cells, further supporting the idea that some orthotopic bipolar cells are GABAergic. A small proportion of bipolar cells in salamander retina contain relatively high levels of both GABA and glutamate. Co-release of these substances by bipolar cells could contribute to the “push-pull” modulation of ganglion cell responses.


2000 ◽  
Vol 17 (1) ◽  
pp. 1-9 ◽  
Author(s):  
DAVID V. POW ◽  
ANITA E. HENDRICKSON

Previous studies show that glycine transporter-1 (glyt-1) is a consistent membrane marker of adult retinal neurons that are likely to release glycine at their synaptic terminals (Pow, 1998; Vaney et al., 1998; Pow & Hendrickson, 1999). The current study investigated when glyt-1 immunoreactivity appeared in the postnatal rat retina, and whether all glycine-containing neurons also labelled for glyt-1. Ganglion cells, horizontal cells, and photoreceptors showed transient labelling. Many cells in the ganglion cell layer are immunoreactive for both glycine and glyt-1 at postnatal day (Pd) 1 but both are minimal by Pd5. Transient immunoreactivity for both glyt-1 and glycine was observed in presumptive horizontal cells between Pd5 and Pd10. At Pd1 many cells in the outer part of the retina which resembled immature photoreceptors were heavily labelled for glycine, but did not express glyt-1; these disappeared at older ages. These findings suggest diverse mechanisms and transient roles for glycine in the developing rat retina. In the adult rat retina, a subpopulation of amacrine cells are prominently immunoreactive for both glycine and glyt-1. These cells labelled for glycine at Pd1, but did not express significant levels of glyt-1 until Pd5. Processes from these amacrine cells did not reach the inner half of the inner plexiform layer until Pd10–14. Bipolar cells became glycine-IR between Pd10 and Pd14, but consistently lacked any glyt-1 immunoreactivity. This temporal pattern of labelling strongly indicates that bipolar cells label for glycine when gap junctions become functional between glycine/glyt-1 immunoreactive amacrine cells and cone bipolar cells.


1992 ◽  
Vol 9 (3-4) ◽  
pp. 313-323 ◽  
Author(s):  
David M. Sherry ◽  
Robert J. Ulshafer

AbstractImmunocytochemical and autoradiographic methods were used to identify neurons in the pure cone retina of the lizard (Anolis carolinensis) that are likely to employ glutamate (GLU) or aspartate (ASP) as a neurotransmitter.GLU immunocytochemistry demonstrated high levels of endogenous GLU in all cone types and numerous bipolar cells. Moderate GLU levels were found in horizontal and ganglion cells. Müller cells and most amacrine cells had very low GLU levels. GLU immunoreactivity (GLU-IR) in the cones was present from the inner segment to the synaptic pedicle. A large spherical cell type with moderate GLU-IR was identified in the proximal inner plexiform layer (IPL). These cells also contain ASP and have been tentatively identified as amacrine cells. Uptake of [3H]-L-GLU labeled all retinal layers. All cone types and Müller cells sequestered [3H]-D-ASP, a substrate specific for the GLU transporter.Anti-ASP labeling was observed in cones, horizontal cells, amacrine cells, and cells in the ganglion cell layer. ASP immunoreactivity (ASP-IR) in the cones was confined to the inner segment. One ASP-containing pyriform amacrine cell subtype ramifying in IPL sublamina b was identified.Analysis of GLU-IR, ASP-IR, and GABA-IR on serial sections indicated that there were two distinct populations of horizontal cells in the Anolis retina: one containing GABA-IR, GLU-IR, and ASP-IR; and another type containing only GLU-IR and ASP-IR. Light GLU-IR was frequently found in GABA-containing amacrine cells but ASP-IR was not.The distinct distributions of GLU and ASP may indicate distinctly different roles for these amino acids. GLU, not ASP, is probably the major neurotransmitter in the cone-biploar-ganglion cell pathway of the Anolis retina. Both GLU and ASP are present in horizontal cells and specific subpopulations of amacrine cells, but it is unclear if GLU or ASP have a neurotransmitter role in these cells.


1982 ◽  
Vol 47 (5) ◽  
pp. 928-947 ◽  
Author(s):  
R. Nelson

1. In a perfused eyecup preparation, AII amacrine cells of the cat retina were penetrated with glass microelectrodes and their electrical responses to photic stimuli recorded. 2. Intracellular injections of the stains Procion, lucifer, or horseradish peroxidase revealed dendritic tree diameters of 30-80 micrometers (48 +/- 16 micrometers, mean +/0 SD) and cell body diameters from 7 to 12 micrometers (9 +/- 3 micrometers) for these cells. The dendrites were broadly stratified throughout the inner plexiform layer (IPL) but possessed large, terminal varicosities in the IPL and inner nuclear lyer (INL) proximal to the cell body. 3. The waveform of these cells in response to photic stimulation suggested division into four components: a) an initial rapid depolarization of the cell membrane followed by a slower decay toward the dark level; b) suppression of the dark noise of the cell; c) with dim or moderately intense stimuli, an off-hyperpolarization; d) in some cases a hyperpolarizing surround response. 4. The receptive fields of AII cells have been characterized using spatial stimuli consisting of long narrow slits. Curves have been fitted to spatial data using two space constants, one for the center mechanism and an opposing one for the surround. For the central mechanism, space constants ranged from 20 to 80 micrometers (46 +/- 22 micrometers), while for the surround they ranged from 60 to 130 micrometers (85 +/- 28 micrometers). The mean half-width of the center mechanism, calculated from the mean space constant, was about 0.25 degrees of visual angle (64 micrometers). The receptive-field properties of AII amacrine cells resemble those of center-depolarizing bipolar cells of other species. 5. Spectral studies of AII amacrine cells reveal that they are rod driven at all criterion voltage levels. Furthermore, adaptation of the rods by rod-saturating backgrounds eliminates 95% of the response amplitude of the AII amacrine cells. Under these conditions the tiny response component remaining is driven by the cat's long wavelength (556-nm peak) cones. 6. AII amacrine cells depolarize to rod stimulation more rapidly than other rod-dominated cells, such as rod bipolar cells, which hyperpolarize. For stimuli corresponding to about 10% of rod saturation, the latency to half-maximum amplitude is about 65 ms for AII cells, 40 ms faster than rod-dominated hyperpolarizing units. The leading edge of the response waveform for AII cells is also much more restricted in time. With the above stimulus it requires about 20 ms to increase from 25 to 75% of its peak, a period almost 4 times shorter than required by rod-dominated S-potential responses. With saturating stimuli the AII response requires only 5 ms to increase from 25 ot 75% of its peak. 7. Although prominent in the rod system, AII amacrine cells do not appear to be able to detect single quantum events. Threshold signals require the bleaching of about 200 rhodopsin molecules within a receptive field containing some 1,300 rods...


1999 ◽  
Vol 16 (1) ◽  
pp. 169-177 ◽  
Author(s):  
PU QIN ◽  
ROBERTA G. POURCHO

The distribution of AMPA-selective glutamate receptor subunits was studied in the cat retina using antisera against GluR1 and GluR2/3. Both antisera were localized in postsynaptic sites in the outer plexiform layer (OPL) as well as the inner plexiform layer (IPL). Immunoreactivity for GluR1 was seen in a subpopulation of OFF cone bipolar cells and a number of amacrine and ganglion cells. Within the IPL, processes staining for GluR1 received input from OFF and ON cone bipolar cells but not from rod bipolars. Labeling for GluR2/3 was seen in horizontal cells, an occasional cone bipolar cell, and numerous amacrine and ganglion cells. In the IPL, GluR2/3 staining was postsynaptic to cone bipolar cells in both sublaminae. AII amacrine cells which receive rod bipolar input were also labeled for GluR2/3. With both antisera, staining was limited to a single member of the bipolar dyad complex, providing morphological evidence for functional diversity in glutamatergic pathways.


1989 ◽  
Vol 2 (5) ◽  
pp. 425-435 ◽  
Author(s):  
Roberta G. Pourcho ◽  
Michael T. Owczarzak

AbstractThe distribution of GABA-like immunoreactivity in the cat retina was studied through the use of preembedding immunocytochemistry for light microscopy and by postembedding immunogold techniques for electron microscopy. Staining was observed in both inner and outer plexiform layers. Approximately 30% of the somata in the amacrine portion of the inner nuclear layer were immunoreactive and included amacrine and interplexiform cells. Horizontal cells and a subpopulation of cone bipolar cells were also stained. In the ganglion cell layer, staining was observed in both small- and medium-sized neurons. GABA-labeled amacrine cells were presynaptic to somata of amacrine cells and to dendrites of amacrine, bipolar, and ganglion cells. Bipolar cells were a major target, receiving more than 60% of all labeled synapses in the inner plexiform layer. Many of these contacts were reciprocal synapses. These findings support a major role for GABA-labeled amacrines in providing feedback inhibition to bipolar cells in the inner retina.


2004 ◽  
Vol 21 (2) ◽  
pp. 107-117 ◽  
Author(s):  
STEPHEN L. MILLS ◽  
KENNETH C. CATANIA

The retina consists of many parallel circuits designed to maximize the gathering of important information from the environment. Each of these circuits is comprised of a number of different cell types combined in modules that tile the retina. To a subterranean animal, vision is of relatively less importance. Knowledge of how circuits and their elements are altered in response to the subterranean environment is useful both in understanding processes of regressive evolution and in retinal processing itself. We examined common cell types in the retina of the naked mole-rat,Heterocephalus glaberwith immunocytochemical markers and retrograde staining of ganglion cells from optic nerve injections. The stains used show that the naked mole-rat eye has retained multiple ganglion cell types, 1–2 types of horizontal cell, rod bipolar and multiple types of cone bipolar cells, and several types of common amacrine cells. However, no labeling was found with antibodies to the dopamine-synthesizing enzyme, tyrosine hydroxylase. Although most of the well-characterized mammalian cell types are present in the regressive mole-rat eye, their structural organization is considerably less regular than in more sighted mammals. We found less precision of depth of stratification in the inner plexiform layer and also less precision in their lateral coverage of the retina. The results suggest that image formation is not very important in these animals, but that circuits beyond those required for circadian entrainment remain in place.


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