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Outer Plexiform Layer (outer + plexiform_layer)
Selected AbstractsEvidence for the involvement of purinergic P2X7 receptors in outer retinal processingEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 1 2006Theresa Puthussery Abstract Extracellular ATP mediates fast excitatory neurotransmission in many regions of the central nervous system through activation of P2X receptors. Although several P2X receptor subunits have been identified in the mammalian retina, little is known about the functional role of these receptors in retinal signalling. The purpose of the present study was to investigate whether purinergic P2X7 receptors are involved in outer retinal processing by assessing receptor localization, degradation of extracellular ATP and the effect of functional activation of P2X7 receptors on the electroretinogram (ERG). Using light and electron microscopy, we demonstrated that P2X7 receptors are expressed postsynaptically on horizontal cell processes as well as presynaptically on photoreceptor synaptic terminals in both the rat and marmoset retina. Using an enzyme cytochemical method, we showed that ecto-ATPases are active in the outer plexiform layer of the rat retina, providing a mechanism by which purinergic synaptic transmission can be rapidly terminated. Finally, we evaluated the role of P2X7 receptors in retinal function by assessing changes to the ERG response of rats after intravitreal delivery of the P2X7 receptor agonist benzoyl benzoyl ATP (BzATP). Intravitreal injection of BzATP resulted in a sustained increase (up to 58%) in the amplitude of the photoreceptor-derived a-wave of the ERG. In contrast, BzATP caused a transient reduction in the rod- and cone-derived postreceptoral responses. These results provide three lines of evidence for the involvement of extracellular purines in outer retinal processing. [source] The immunocytochemical localization of connexin 36 at rod and cone gap junctions in the guinea pig retinaEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 11 2003Eun-Jin Lee Abstract Connexin 36 (Cx36) is a channel-forming protein found in the membranes of apposed cells, forming the hexameric hemichannels of intercellular gap junction channels. It localizes to certain neurons in various regions of the brain including the retina. We characterized the expression pattern of neuronal Cx36 in the guinea pig retina by immunocytochemistry using specific antisera against Cx36 and green/red cone opsin or recoverin. Strong Cx36 immunoreactivity was visible in the ON sublamina of the inner plexiform layer and in the outer plexiform layer, as punctate labelling patterns. Double-labelling experiments with antibody directed against Cx36 and green/red cone opsin or recoverin showed that strong clustered Cx36 immunoreactivity localized to the axon terminals of cone or close to rod photoreceptors. By electron microscopy, Cx36 immunoreactivity was visible in the gap junctions as well as in the cytoplasmic matrices of both sides of cone photoreceptors. In the gap junctions between cone and rod photoreceptors, Cx36 immunoreactivity was only visible in the cytoplasmic matrices of cone photoreceptors. These results clearly indicate that Cx36 forms homologous gap junctions between neighbouring cone photoreceptors, and forms heterologous gap junctions between cone and rod photoreceptors in guinea pig retina. This focal location of Cx36 at the terminals of the photoreceptor suggests that rod photoreceptors can transmit rod signals to the pedicle of a neighbouring cone photoreceptor via Cx36, and that the cone in turn signals to corresponding ganglion cells via ON and OFF cone bipolar cells. [source] Radial migration of developing microglial cells in quail retina: A confocal microscopy studyGLIA, Issue 3 2004Ana 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] Synaptic localization of neuroligin 2 in the rodent retina: Comparative study with the dystroglycan-containing complexJOURNAL OF NEUROSCIENCE RESEARCH, Issue 4 2010Leona 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] Selective projection patterns from subtypes of retinal ganglion cells to tectum and pretectum: Distribution and relation to behaviorTHE JOURNAL OF COMPARATIVE NEUROLOGY, Issue 4 2009Marcus Robert Jones Abstract An important issue to understand is how visual information can influence the motor system and affect behavior. Using the lamprey (Petromyzon marinus) as an experimental model we examined the morphological subtypes of retinal ganglion cells and their projection pattern to the tectum, which controls eye, head, and body movements, and to the pretectum, which mediates both visual escape responses and the dorsal light response. We identified six distinct morphological types of retinal ganglion cell. Four of these distribute their dendrites in the inner plexiform layer (image forming layer) and project in a retinotopic manner to all areas of the tectum. The posterior part of the retina has the highest density of ganglion cells and projects to the rostral part of the tectum, in which the visual field in front of the lamprey will be represented. From this area both orienting and evasive behaviors can be elicited. In contrast, pretectum receives input from two ganglion cells types that send their dendrites only to the outer plexiform layer or the outer limiting membrane and therefore may directly contact photoreceptors, and transmit information without additional delay to pretectum, which may be particularly important for visual escape responses. One of these two types, the bipolar ganglion cell, is only found in a small patch of retina just ventral of the optic nerve. Due to its distribution, morphology, and projections we suggest that this cell may control the dorsal light response. J. Comp. Neurol. 517:257,275, 2009. © 2009 Wiley-Liss, Inc. [source] Selective projection patterns from subtypes of retinal ganglion cells to tectum and pretectum: Distribution and relation to behaviorTHE JOURNAL OF COMPARATIVE NEUROLOGY, Issue 3 2009Marcus Robert Jones Abstract An important issue to understand is how visual information can influence the motor system and affect behavior. Using the lamprey (Petromyzon marinus) as an experimental model we examined the morphological subtypes of retinal ganglion cells and their projection pattern to the tectum, which controls eye, head, and body movements, and to the pretectum, which mediates both visual escape responses and the dorsal light response. We identified six distinct morphological types of retinal ganglion cell. Four of these distribute their dendrites in the inner plexiform layer (image forming layer) and project in a retinotopic manner to all areas of the tectum. The posterior part of the retina has the highest density of ganglion cells and projects to the rostral part of the tectum, in which the visual field in front of the lamprey will be represented. From this area both orienting and evasive behaviors can be elicited. In contrast, pretectum receives input from two ganglion cells types that send their dendrites only to the outer plexiform layer or the outer limiting membrane and therefore may directly contact photoreceptors, and transmit information without additional delay to pretectum, which may be particularly important for visual escape responses. One of these two types, the bipolar ganglion cell, is only found in a small patch of retina just ventral of the optic nerve. Due to its distribution, morphology, and projections we suggest that this cell may control the dorsal light response. J. Comp. Neurol. 517:257,275, 2009. © 2009 Wiley-Liss, Inc. [source] Selective projection patterns from subtypes of retinal ganglion cells to tectum and pretectum: Distribution and relation to behaviorTHE JOURNAL OF COMPARATIVE NEUROLOGY, Issue 3 2009Marcus Robert Jones Abstract An important issue to understand is how visual information can influence the motor system and affect behavior. Using the lamprey (Petromyzon marinus) as an experimental model we examined the morphological subtypes of retinal ganglion cells and their projection pattern to the tectum, which controls eye, head, and body movements, and to the pretectum, which mediates both visual escape responses and the dorsal light response. We identified six distinct morphological types of retinal ganglion cell. Four of these distribute their dendrites in the inner plexiform layer (image forming layer) and project in a retinotopic manner to all areas of the tectum. The posterior part of the retina has the highest density of ganglion cells and projects to the rostral part of the tectum, in which the visual field in front of the lamprey will be represented. From this area both orienting and evasive behaviors can be elicited. In contrast, pretectum receives input from two ganglion cells types that send their dendrites only to the outer plexiform layer or the outer limiting membrane and therefore may directly contact photoreceptors, and transmit information without additional delay to pretectum, which may be particularly important for visual escape responses. One of these two types, the bipolar ganglion cell, is only found in a small patch of retina just ventral of the optic nerve. Due to its distribution, morphology, and projections we suggest that this cell may control the dorsal light response. J. Comp. Neurol. 517:257,275, 2009. © 2009 Wiley-Liss, Inc. [source] Synaptic localization of P2X7 receptors in the rat retinaTHE JOURNAL OF COMPARATIVE NEUROLOGY, Issue 1 2004Theresa 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] Localization of voltage-sensitive L-type calcium channels in the chicken retinaCLINICAL & EXPERIMENTAL OPHTHALMOLOGY, Issue 3 2001Sally I Firth PhD ABSTRACT L-type calcium channels have been associated with synaptic transmission in the retina, and are a potential site for modulation of the release of neurotransmitters. The present study documents the immunohistochemical localization of neuronal ,1 subunits of L-type calcium channels in chicken retina, using antibodies to the ,1c, ,1d and ,1f subunits of L-type calcium channels. The ,1c-like subunits were localized to Müller cells, with predominantly radial processes, and a prominent band of horizontal processes in the outer plexiform layer. The antibody to ,1d subunits labelled most, if not all, cell bodies. The antibody to a human ,1f subunit strongly labelled photoreceptor terminals. Fainter immunoreactivity was detected in the inner segments of the photoreceptors, a subset of amacrine cells, two bands of labelling in the inner plexiform layer and many ganglion cells. The differential cellular distributions of these ,1-subunits suggests subtle functional differences in their roles at different cellular locations. [source] Synaptic localization of P2X7 receptors in the rat retinaTHE JOURNAL OF COMPARATIVE NEUROLOGY, Issue 1 2004Theresa 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 distribution of neuroglobin in mouse eyeACTA OPHTHALMOLOGICA, Issue 2009Y 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] | |||||||||||||