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S Yazulla

Publications and source records attributed to S Yazulla.

At least 19 recordsLinked to original sources
PubMed2001

Localization of the AMPA subunit GluR2 in the outer plexiform layer of goldfish retina.

L-glutamate, the photoreceptor neurotransmitter, depolarizes horizontal cells and OFF bipolar cells by ionotropic AMPA-glutamate receptors. The AMPA-receptor subunit (GluR4) is localized to dendrites of OFF bipolar cells in goldfish retina. Here, we used immunohistochemical techniques to identify AMPA-receptor subunits on horizontal cell dendrites. A monoclonal antibody against rat GluR2, with high sequence homology to the recently cloned goldfish GluR2a receptor, was used for light- and electron-microscopical immunocytochemistry. Light- and dark-adapted retinas were analyzed, with no major difference in results. GluR2-immunoreactivity (IR) was restricted to a narrow band in the outer plexiform layer, in which it appeared as bright dome-shaped structures amidst numerous puncta. At the ultrastructural level, GluR2-IR was found in horizontal cell dendrites that invaginated cones and rods. Dendrites of OFF bipolar cells were not labeled. GluR2-IR was present mostly in horizontal cell dendrites that were the lateral elements of the triad, rather than in dendrites that were the central elements. In light-adapted retinas, GluR2-IR was found in many horizontal cell spinules. GluR2-IR was observed, on occasion, in a mixed rod/cone (Mb) ON bipolar cell process that innervated rod spherules. Verification of the Mb ON bipolar cell was made by protein kinase C and metabotropic mGluR1alpha immunolabeling. The presence of GluR2-IR in lateral elements suggests that lateral horizontal cell dendrites are postsynaptic to cones rather than only sites of feedback inhibition. All horizontal cell types express the GluR2 subunit, uniquely differentiating themselves from OFF bipolar cells that express the GluR4 subunit. This differentiation most likely has a major influence on the glutamate pharmacology and response kinetics of these cell types to glutamate.

Animals↗
PubMed2001

Voltage-dependent sodium channels are expressed in nonspiking retinal bipolar neurons.

Retinal bipolar neurons transmit visual information by means of graded synaptic potentials that spread to the synaptic terminal without sodium-dependent action potentials. Although action potentials are not involved, voltage-dependent sodium channels may enhance subthreshold depolarizing potentials in the dendrites and soma of bipolar cells, as they do in other CNS neurons. We report here that voltage-dependent sodium currents are observed in a subset of bipolar neurons from goldfish retina. Single-cell reverse transcriptase-PCR identified four different sodium channel alpha subunits in goldfish bipolar cells, putatively corresponding to the mammalian voltage-gated sodium channels Na(v)1.1, Na(v)1.2, Na(v)1.3, and Na(v)1.6. The amount of sodium current was largest in cells with smaller synaptic terminals, which probably represent cone bipolar cells. Localization of sodium channel immunoreactivity in goldfish retina confirmed the expression of voltage-gated sodium channels in cone bipolar cells of both ON and OFF types. Both immunocytochemical and physiological evidence suggests that the sodium channels are localized to the soma and dendrites where they may play a role in transmission of synaptic signals, particularly in the long, thin dendrites of cone bipolar cells.

Animals↗
PubMed2001

Neurochemical anatomy of the zebrafish retina as determined by immunocytochemistry.

The zebrafish retina is rapidly becoming a major preparation for the study of molecular genetic mechanisms underlying neural development and visual behavior. Studies utilizing retinal mutants would benefit by the availability of a data base on the distribution of neurotransmitter systems in the wild-type fish. To this end, the neurochemical anatomy of the zebrafish retina was surveyed by light microscopic immunocytochemistry. An extensive series of 60 separate antibodies were used to describe the distribution of major transmitter systems and a variety of neuron-associated membrane channels and proteins. These include markers (i.e., antibodies against enzymes, receptors, transporters) for transmitters: GABA, glycine, glutamate, biogenic amines, acetylcholine, cannabinoids and neuropeptides; as well as a sample of voltage-gated channels and synapse associated membrane proteins. Discussion of the comparative localization of these antibodies is restricted to other teleost fishes, particularly goldfish. Overall, there was great similarity in the distribution of the various markers, as might be expected. However, there were some notable differences, including several antibodies that did not label zebrafish at all, even though goldfish retinas that were processed in parallel, labeled beautifully. This survey is extensive, but not exhaustive, and hopefully will serve as a valuable resource for future studies of the zebrafish retina.

Animals↗
PubMed2000

Immunocytochemical localization of the glutamate transporter GLT-1 in goldfish (Carassius auratus) retina.

Glutamate is the major excitatory neurotransmitter in the retina of vertebrates. Electrophysiological experiments in goldfish and salamander have shown that neuronal glutamate transporters play an important role in the clearance of glutamate from cone synaptic clefts. In this study, the localization of the glutamate transporter GLT-1 has been investigated immunocytochemically at the light and electron microscopical levels in the goldfish retina using a GLT-1-specific antibody. GLT immunoreactivity (IR) was observed at the light microscopical level in Müller cells, bipolar cells, the outer plexiform layer (OPL), and the inner plexiform layer (IPL). At the electron microscopical level, membrane-bound and cytoplasmic GLT-IR in the OPL was located in finger-like protrusions of the cone terminal located near the invaginating postsynaptic processes of bipolar and horizontal cells. GLT-IR was not observed in the vicinity of synaptic ribbons. This location of GLT-1 allows modulation of the glutamate concentration in the synaptic cleft, thereby shaping the dynamics of synaptic transmission between cones and second-order neurons. In the inner IPL, GLT-IR was observed in the cytoplasm and was membrane bound in mixed rod/cone bipolar cell terminals and cone bipolar cell terminals. The membrane-bound GLT-1 was generally observed at some distance from the synaptic ribbon. The morphology of the bipolar cell terminal together with the localization of GLT-1 suggests that at least these glutamate transporters are not primarily involved in rapid uptake of glutamate release by the bipolar cells. The GLT-IR in the cytoplasm of Müller cells was located throughout the entire goldfish retina from the outer limiting membrane to the inner limiting membrane. The location of GLT-1 in Müller cells is consistent with the role of Müller cells in converting glutamate to glutamine.

ATP-Binding Cassette Transporters↗
PubMed1999

Immunocytochemical localization of cannabinoid CB1 receptor and fatty acid amide hydrolase in rat retina.

Cannabinoids have major effects on central nervous system function. Recent studies indicate that cannabinoid effects on the visual system have a retinal component. Immunocytochemical methods were used to localize cannabinoid CB1 receptor immunoreactivity (CB1R-IR) and an endocannabinoid (anandamide and 2-arachidonylglycerol) degradative enzyme, fatty acid amide hydrolase (FAAH)-IR, in the rat retina. Double labeling with neuron-specific markers permitted identification of cells that were labeled with CB1R-IR and FAAH-IR. CB1R-IR was observed in all cells that were protein kinase C-immunoreactive (rod bipolar cells and a subtype of GABA-amacrine cell) as well as horizontal cells (identified by calbindin-IR). There was also punctate CB1R-IR in the distal one-third of the inner plexiform layer (IPL) that could not be assigned to a cell type. FAAH-IR was most prominent in large ganglion cells, whose dendrites projected to a narrow band in the proximal IPL. Weaker FAAH-IR was observed in the soma of horizontal cells (identified by calbindin-IR); the soma of large, but not small, dopamine amacrine cells (identified by tyrosine hydroxylase-IR); and dendrites of orthotopic- and displaced-starburst amacrine cells (identified by choline acetyltransferase-IR) but in less than 50% of the starburst amacrine cell somata. The extensive distribution of CB1R-IR on horizontal cells and rod bipolar cells indicates a role of endocannabinoids in scotopic vision, whereas the more widespread distribution of FAAH-IR indicates a complex control of endocannabinoid release and degradation in the retina.

Amidohydrolases↗
PubMed1999

Dopamine D1-receptor immunolocalization in goldfish retina.

Dopamine, a neuromodulator in the vertebrate retina, is involved in numerous functions related to light adaptation. However, unlike in mammals, localization of retinal D1-dopamine receptors in nonmammalian vertebrates has been hampered due to a lack of antisera. To address this problem, an antiserum against the 18 C-terminal amino acids of the goldfish D1 receptor (gfD1r) was generated in chicken eggs and tested in retinae of goldfish and rat, and rat caudate putamen, by using immunoblots and light microscopic immunocytochemistry. No labeling was observed in any tissue or immunoblots with preabsorbed gfD1r antiserum. Immunoblot analysis of goldfish retina revealed a single band at about 101 kDa. The patterns of gfD1r immunoreactivity (gfD1r-IR), found in rat caudate putamen and rat retina were virtually identical to that previously reported with other D1-receptor ligands and antisera. In goldfish retina, gfD1r-IR was most intense over cell bodies in the ganglion cell layer, amacrine cells in the proximal inner nuclear layer (INL), and bipolar cells in the distal INL. Weaker gfD1r-IR was observed over horizontal cell bodies and both plexiform layers. Müller cells and axons of cone photoreceptors were labeled as well. Double labeling showed that all protein kinase C-immunoreactive bipolar cells (ON type) were gfD1r-IR on the soma, axon terminal, and dendrites. All glutamate decarboxylase-immunoreactive (i.e., gamma-aminobutyric acid utilizing) amacrine cells and horizontal cells were gfD1r-IR. Retinal D1r distribution is more extensive than dopamine neuron innervation, but is consistent with physiologic estimates of dopamine function, suggestive of both wiring and volume transmission of dopamine in the retina. The gfD1r antiserum displays cross-reactivity to dopamine receptors in a mammal and a nonmammal and should prove useful in future studies of dopaminergic systems.

Amino Acid Sequence↗
PubMed1999

Co-localization of Shaker A-type K+ channel (Kv1.4) and AMPA-glutamate receptor (GluR4) immunoreactivities to dendrites of OFF-bipolar cells of goldfish retina.

Immunocytochemical methods were used to determine the comparative distribution of Shaker Kv1.4 and Shal Kv4.2 A-type voltage-gated K(+) channels and AMPA-type GluR4 glutamate receptors in the goldfish retina. Kv1.4-immunoreactivity (IR) was restricted to a very narrow band of bright puncta and filamentous processes in the outer plexiform layer (OPL), whereas GluR4-IR was found in radial processes of Müller cells in addition to a narrow band in the OPL. Kv4.2-IR was most prominent over cell bodies of horizontal cell, amacrine cells and ganglion cells, with very weak labeling over the synaptic terminal of cone photoreceptors. Double label experiments revealed complete co-localization of Kv1.4-IR and GluR4-IR in the OPL and showed that the Kv1.4 puncta in the OPL appeared enclosed by the Kv4.2-IR cone terminals. Electron microscopical immunocytochemistry showed that Kv1.4-IR and GluR4-IR were restricted to the dendrites of OFF-bipolar cells that innervated cone photoreceptor terminals and thin processes that coursed between the rod and cone terminals in the OPL. These data are consistent with other studies demonstrating the selective clustering of A-type voltage-gated K(+) channels and ionotropic glutamate receptors. However, they differ from mammalian preparations in which Shal-like Kv4.2 rather than Shaker-like Kv1.4 co-localize postsynaptically with glutamate receptors.

Animals↗
PubMed1998

Differential distribution of Shaker-like and Shab-like K+-channel subunits in goldfish retina and retinal bipolar cells.

The distributions of Shaker subfamily Kv1.1 and Kv1.2 and Shab subfamily Kv2.1 subunits of voltage-gated K+ channels were determined in the retina and ON bipolar cells of goldfish by using double-label light and electron microscopic immunocytochemistry. All labeling to be described was blocked by preabsorption of the primary antibodies with antigen. The retina was labeled throughout with all three antibodies. However, labeling was densest in the inner plexiform layer for Kv1.1, more concentrated in the outer nuclear layer for Kv2.1, and uniform throughout for Kv1.2. All ON mixed rod/cone (mb) and cone (cb) bipolar somata and the proximal portions of their axons and dendrites were labeled for anti-Kv1.1, Kv1.2, and Kv2.1. Labeling of axons rarely extended over the mb axon terminal. Only Kv1.2 antibodies labeled mb bipolar cell dendrites in the outer plexiform layer. No evidence for Kv1.1, 1.2, or 2.1 antibody labeling of OFF bipolar cells was found. Ultrastructurally, Kv1.2-immunoreactivity was associated with the plasma membrane of bipolar cell bodies and with dendrites that make narrow-cleft junctions with cone terminals (ON-type). Kv immunoreactivity was not found associated with presynaptic membranes in the inner plexiform layer and was found only rarely with membranes, postsynaptic to an amacrine cell process. Although both Shaker and Shab subfamilies include delayed rectifiers, their activation properties differ, suggesting differential modulation of K+ conductances in bipolar cells based not only on the presence or absence of rod photoreceptor input but also whether the bipolar cells are of the ON or OFF type.

Animals↗
PubMed1997

Differential reinnervation of retinal bipolar cell dendrites and axon terminals by dopamine interplexiform cells following dopamine depletion with 6-OHDA.

Depletion of retinal dopamine in goldfish increases light sensitivity at photopic backgrounds. As horizontal cells appear not to be involved with this effect (Yazulla and Studholme [1995] Vis. Neurosci. 12:827-837), we investigated the innervation patterns of the ON rod/cone bipolar cells (ON-BC) by dopaminergic interplexiform cells (DA-IPCs) normally and during the period of neogeneration of new DA-IPCs at the marginal zone following DA-IPC destruction. DA-IPCs were destroyed via intraocular injection of 6-hydroxydopamine over 2 successive days. Controls and 1 year post-injection retinas were double labeled for protein kinase C and tyrosine hydroxylase (TH) immunocytochemistry to identify the ON-BCs and the DA-IPCs, respectively. Double-labeled 25 microns tissue sections were examined on a confocal laser scanning microscope by using dual channel immunofluorescence acquisition. Image stacks were analyzed for DA-IPC/ON-BC contacts in the distal inner nuclear layer (INL) and inner plexiform layer (IPL). Image stacks were rotated 180 degrees with respect to each other and reanalyzed to determine potential randomness of the contacts. For control retinas there were 1.8 contacts/axon terminal in the IPL (n = 165) and 9.4 contacts/ON-BC in the distal INL (n = 28). At 1 year after injection, reinnervation of TH-immunoreactive boutons in the retina recovered to 16% of control in the IPL but only 10% in the distal INL. Establishment of DA-IPC/ON-BC contacts recovered to 36% of control for ON-BC axon terminals (n = 103), whereas there was no recovery of contacts in the distal INL (n = 30). Reinnervation of ON-BC by DA-IPCs preferentially targets the axon terminals. The absence of reinnervation of bipolar cell dendrites by DA-IPCs may account for the persistence of the increased light sensitivity following retinal dopamine depletion. Thus, dopamine input to ON-BCs in the outer retina maybe involved in setting background sensitivity under photopic conditions.

Animals↗
PubMed1997

Light adaptation affects synaptic vesicle density but not the distribution of GABAA receptors in goldfish photoreceptor terminals.

GABA is a likely feedback transmitter from H1 horizontal cells to cone photoreceptors in fish retinas. Spinules arise from H1 cell dendrites in light-adapted retinas, are correlated with responses attributed to feedback, and have been proposed to be the GABA release sites. We used mAb 62-3G1, an antibody against the beta 2/beta 3 subunits of the GABAA receptor complex, to visualize GABAA receptor immunoreactivity (GABAr-IR) in photoreceptors as a function of light and dark adaptation at the electron microscopical level. Regardless of adaptation, GABAr-IR was restricted to the synaptic terminals of all cones and most rods; synaptic vesicular membrane and plasma membrane, exhibited GABAr-IR. Contrary to expectations, the density of GABAr-IR was least on the plasma membrane within the invagination, regardless of the presence or absence of spinules. Dense GABAr-IR was observed on the lateral surface of cone pedicles, on cone processes proximal to the invagination, and on presumed telodendria from nearby cones. There was no difference in GABAr-IR of rod plasma membranes within or outside of the invagination or with adaptation. The only novel effect of adaptation was in regards to the density of synaptic vesicles. Cones showed a 29% increase in vesicle density with dark adaptation, whereas rods showed a 17% decrease. We conclude that all goldfish photoreceptors will be GABA-sensitive and that the sensitivity is distributed over the surface of the synaptic terminal rather than localized to within the invagination. The role of spinules in GABA release remains to be determined, but we conclude that spinules are not related to the GABA sensitivity of goldfish photoreceptors.

Adaptation, Ocular↗
PubMed1997

Differences in the retinal GABA system among control, spastic mutant and retinal degeneration mutant mice.

Immunocytochemical methods were used to compare the GABA system in control mice and two mutant strains: spastic which has reduced glycine receptors and retinal degeneration mutant in which the photoreceptors degenerate and reportedly have increased GABA and GAD levels. We found that the spastic mutant retina had reduced GABA-immunoreactivity (IR) in the proximal retina, reduced staining for GAD-1440 in the OPL, and reduced GABAA receptor staining in the OPL, compared to control. The retinal degeneration mutant retinas had enhanced GABA-IR throughout the retina, particularly in Müller cells, bipolar cells and IPL, and enhancement of GABAA receptor staining in the OPL, compared to control. The distributions of GABA-IR, GAD-1440-IR and GABAA receptor-IR in retinas of spastic mutant mice that also expressed the retinal degeneration phenotype resembled those found in retinas of mice that expressed only the retinal degeneration phenotype rather than those that expressed only the spastic mutation. No differences were observed among the conditions for GAD-65, GAD-67 or GABA-T. Our results with the spastic and retinal degeneration mutant mice demonstrate that attenuation in the glycinergic system and photoreceptor degeneration, respectively, is accompanied by alterations in different aspects of the GABA system, giving impetus for caution in the interpretation of experiments involving genetic manipulation of complex phenotypes.

Animals↗
PubMed1997

Electrogenic hyperpolarization-elicited chloride transporter current in blue cones of zebrafish retinal slices.

Voltage-activated currents in blue cones of the retinal slice of zebrafish were characterized using whole cell recording techniques. Depolarizing-elicited currents were recorded: an outward tetraethylammonium (TEA)-sensitive K+ current (IKx), an outward Ca(2+)-activated Cl- current (ICl(Ca)), from which we inferred an inward Ca2+ current (ICa) as well as a hyperpolarizing-elicited nonselective inward cation current (Ih). In addition, hyperpolarizing steps elicited an outward current (Iout-h) in about one-third of the blue cones. Iout-h seems to be carried by inward transported Cl- because it was abolished by equimolar substitution of bath Cl- with acetate; equimolar substitution of Na+ with choline or TEA had no effect; it was not affected by Cl- channel blockers, anthracene-9-carboxylic acid, 4,4'-diisothiocyanostilbene-2.2'-disulfonic acid, N-phenylanthranilic acid (DPC), niflumic acid, and 4-acetamido-4'-isothiocyanostilbene-2,2'-disulfonic acid but was suppressed by Cl- transporter blockers acetalzolamide, bumetanide, N-ethylmaleimide, furosemide, and vanadate, and no reversal potential was found. In addition, this current was suppressed by ouabains but unrelated to their Na(+)-K(+)-ATPase inhibitory effect, was not suppressed by Co2+ or nifedipine, was not affected by the gap junction decoupler, 2-octanol, was increased by bath application of Cs+, presumably due to suppression of Ih, which was masked by Iout-h, and was suppressed by intensive light. Similar current also was found in the short cones and double cones. As Iout-h operates over the same voltage range, and with similar magnitude and time course as Ih, we suggest that Iout-h contributes to the modulation of the photoresponse of cones.

Animals↗
PubMed1996

Dopaminergic control of light-adaptive synaptic plasticity and role in goldfish visual behavior.

Dopamine has been implicated in processes of retinal light and dark adaptation. In goldfish retina, horizontal cell dendrites elaborate neurite processes (spinules) into cone terminals, in a light- and dopamine-dependent manner. However, the functions of retinal dopamine and the horizontal cell spinules in visual behavior are unknown. These issues were addressed in behavioral, electroretinographic, and anatomical studies of normal fish and those with unilateral depletion of retinal dopamine induced by intraocular (i.o.) injections with 6-hydroxydopamine (6-OHDA). Dopamine interplexiform cells (DA-IPC) disappear within 2 weeks after 6-OHDA injection; cell bodies appear at the marginal zone within 6 weeks at which time neurites slowly reinnervate the retina with a sparse plexus over the next 12 months. We found that dopamine depletion increased light sensitivity at photopic but not scotopic backgrounds by 2.5 log units, an effect mimicked by i.o. injections of dopamine D1 and D2 antagonists. The ERG b-wave increment thresholds were the same for control and dopamine depleted eyes, indicating a normal transition from rod to cone systems in the ON pathway. Light-dependent spinule formation was reduced by about 60% in dopamine-depleted retinas, but returned to normal by 3 months and 9 months after injection in the entire retina, even areas not directly innervated with DA-IPC processes. Spinule formation in vivo was inhibited 50% with i.o. injection of SCH 23390 in control retinas as well as throughout 3 month 6-OHDA injected retinas, including DA-IPC free areas. This latter result indicates a volume effect of dopamine, diffusing laterally through the retina over several millimeters, in regulating spinules. We conclude that DA-IPCs regulate sensitivity to background at photopic levels not via the ON pathway, but perhaps the OFF pathway. Goldfish display both increased sensitivity to light and a normal Purkinje shift in the ERG b-wave whether or not horizontal cell spinules are present, indicating that dopamine control of photopic vision in fish is not mediated through light-induced spinule formation of horizontal cell dendrites.

Adaptation, Ocular↗
PubMed1995

Differential effects of dopamine depletion on the distribution of [3H]SCH 23390 and [3H]spiperone binding sites in the goldfish retina.

The distributions of dopamine D1 and D2 receptors were studied in intact goldfish retina with in vitro autoradiography. Specific [3H]SCH 23390 binding (D1 receptors) was greatest over the outer plexiform layer (OPL)/horizontal cell bodies and less so over the inner nuclear and inner plexiform layers (IPL). Specific [3H]spiperone binding (D2 receptors) appeared in two bands, over the OPL/horizontal cell bodies and the IPL. Depletion of retinal dopamine, by intraocular injections of 6-hydroxydopamine, had no effect on the pattern and density of [3H]SCH 23390 binding; however, specific [3H]spiperone binding over the OPL and IPL was virtually eliminated, suggestive of D2 autoreceptors on dopamine interplexiform cells. These data are consistent with electrophysiological studies indicating the presence of D1 and D2 receptors in both plexiform layers of the goldfish retina.

Adrenergic Agents↗
PubMed1994

Heterogeneity of GABAA receptor in goldfish retina.

The possibility of GABAA receptor heterogeneity in goldfish retina was studied with immunocytochemical and biochemical approaches: 1) immunoblotted membrane particulates of goldfish retina with mAb 62-3G1; 2) immunoprecipitation of the detergent-solubilized membrane proteins with mAb 62-3G1 followed by the receptor binding assay; 3) photoaffinity labeling of the membrane particulates with 3H-flunitrazepam (FNZ) and visualization of the labeled receptors by SDS-PAGE and fluorography; 4) dry autoradiography of 3H-muscimol and 3H-FNZ binding sites on frozen sections. Immunoblots showed that 62-3G1 reacted with 55-57.5 kDa M(r) polypeptides, similar to the muscimol-binding subunit of the receptor complex in bovine brain; while 3H-FNZ photoaffinity labeled the 52.5 kDa and 41-43 kDa M(r) polypeptides. Immunoprecipitated receptors bound only 3H-muscimol, not 3H-FNZ. An attempt to precipitate the 3H-FNZ photolabeled polypeptides failed. Dry autoradiography showed 3H-FNZ binding only in the inner plexiform layer (IPL); the binding was enhanced with gamma-aminobutyric acid (GABA) and blocked by clonazepam. In contrast, 3H-muscimol was bound in both the outer plexiform layer (OPL) and IPL, similar to that observed with 62-3G1 immunocytochemistry. We suggest that there are two subtypes of GABAA receptor in the goldfish retina: 1) GABAA receptors that are not linked to a benzodiazepine (BZD) receptor are located in the OPL and at amacrine-to-amacrine and amacrine-to-ganglion cell synapses in the IPL and are recognized by 62-3G1; 2) GABAA receptors that are linked to a BZD receptor are located only in the IPL, largely at amacrine-to-bipolar cell synapses and are not recognized by mAb 62-3G1.

Affinity Labels↗
PubMed1994

Glycine receptors in the retinas of normal and spastic mutant mice.

PURPOSE: Spastic mutant mice have abnormal gait and righting behavior, and the responses of their retinal ganglion cells have recently been shown to be abnormal. The former defects have been linked to a reduction of glycine-receptor density in the spinal cord of spastic mutants, but the cause of the retinal defects has not yet been determined. The authors thus tested for reduced glycine-receptor density in the mutant retina by comparing the levels of glycine receptors in the retinas of spastic mutant mice with those found in normal mice. METHODS: Indirect immunofluorescence histochemistry was employed, using monoclonal antibodies directed against the alpha- and beta-subunits of the receptor and against the 93-kd cytoplasmic receptor-associated protein, gephyrin. RESULTS: In normal mice, all glycine-receptor antibodies labeled two laminae of the inner plexiform layer (IPL): a broad band in the distal third of the IPL and a narrow band in the middle of the IPL. Lighter labeling was also seen in the outer plexiform layer with these antibodies. In spastic mutant mice, the glycine-receptor labeling of the IPL was reduced markedly. However, the overall structure of the spastic mutant retina was not disrupted because the distribution and intensity of both a presynaptic marker (synaptophysin) and a marker for the rod bipolar cell (protein kinase C) in the mutant retina were indistinguishable from those in normal retinas. CONCLUSIONS: The glycine-receptor distribution in normal mice was consistent with that previously reported for the rat and with the distribution of glycine responsiveness of dissociated rodent bipolar cells. The reduced levels of glycine receptors in spastic mice help explain the abnormal ganglion cell responses in the spastic mutant.

Animals↗