scholarly journals Synaptic vesicle dynamics in mouse rod bipolar cells

2008 ◽  
Vol 25 (4) ◽  
pp. 523-533 ◽  
Author(s):  
QUN-FANG WAN ◽  
ALEJANDRO VILA ◽  
ZHEN-YU ZHOU ◽  
RUTH HEIDELBERGER
Keyword(s):  
Synaptic Vesicle ◽  
Time Constant ◽  
Active Zone ◽  
Bipolar Cell ◽  
Visual Information ◽  
Membrane Surface ◽  
Bipolar Cells ◽  
Calcium Dependent ◽  
Vesicle Dynamics ◽  
Rod Bipolar Cells

AbstractTo better understand synaptic signaling at the mammalian rod bipolar cell terminal and pave the way for applying genetic approaches to the study of visual information processing in the mammalian retina, synaptic vesicle dynamics and intraterminal calcium were monitored in terminals of acutely isolated mouse rod bipolar cells and the number of ribbon-style active zones quantified. We identified a releasable pool, corresponding to a maximum of ≈35 vesicles/ribbon-style active zone. Following depletion, this pool was refilled with a time constant of ≈7 s. The presence of a smaller, rapidly releasing pool and a small, fast component of refilling was also suggested. Following calcium channel closure, membrane surface area was restored to baseline with a time constant that ranged from 2 to 21 s depending on the magnitude of the preceding Ca2+ transient. In addition, a brief, calcium-dependent delay often preceded the start of onset of membrane recovery. Thus, several aspects of synaptic vesicle dynamics appear to be conserved between rod-dominant bipolar cells of fish and mammalian rod bipolar cells. A major difference is that the number of vesicles available for release is significantly smaller in the mouse rod bipolar cell, both as a function of the total number per neuron and on a per active zone basis.

scholarly journals Synaptic release at mammalian bipolar cell terminals

2011 ◽  
Vol 28 (1) ◽  
pp. 109-119 ◽  
Author(s):  
QUN-FANG WAN ◽  
RUTH HEIDELBERGER
Keyword(s):  
Bipolar Cell ◽  
Neurotransmitter Release ◽  
Visual Information ◽  
Glutamate Release ◽  
Vital Role ◽  
Bipolar Cells ◽  
Intrinsic Factors ◽  
Synaptic Release ◽  
Presynaptic Mechanisms ◽  
Rod Bipolar Cells

AbstractBipolar cells play a vital role in the transfer of visual information across the vertebrate retina. The synaptic output of these neurons is regulated by factors that are extrinsic and intrinsic. Relatively little is known about the intrinsic factors that regulate neurotransmitter exocytosis. Much of what we know about intrinsic presynaptic mechanisms that regulate glutamate release has come from the study of the unusually large and accessible synaptic terminal of the goldfish rod-dominant bipolar cell, the Mb1 bipolar cell. However, over the past several years, examination of presynaptic mechanisms governing neurotransmitter release has been extended to the mammalian rod bipolar cell. In this review, we discuss the recent advances in our understanding of synaptic vesicle dynamics and neurotransmitter release in rodent rod bipolar cells and consider how these properties help to shape the synaptic output of the mammalian retina.

scholarly journals Diurnal Changes in Exocytosis and the Number of Synaptic Ribbons at Active Zones of an on-Type Bipolar Cell Terminal

2006 ◽  
Vol 96 (4) ◽  
pp. 2025-2033 ◽  
Author(s):  
Court Hull ◽  
Keith Studholme ◽  
Stephen Yazulla ◽  
Henrique von Gersdorff
Keyword(s):  
Synaptic Vesicle ◽  
Bipolar Cell ◽  
Bipolar Cells ◽  
Synaptic Ribbons ◽  
Diurnal Changes ◽  
Synaptic Vesicle Exocytosis ◽  
Pulse Ratio ◽  
Vesicle Exocytosis ◽  
Active Zones ◽  
Vesicle Pool

The number and morphology of synaptic ribbons at photoreceptor and bipolar cell terminals has been reported to change on a circadian cycle. Here we sought to determine whether this phenomenon exists at goldfish Mb-type bipolar cell terminals with the aim of exploring the role of ribbons in transmitter release. We examined the physiology and ultrastructure of this terminal around two time points: midday and midnight. Nystatin perforated-patch recordings of membrane capacitance ( Cm) revealed that synaptic vesicle exocytosis evoked by short depolarizations was reduced at night, even though Ca2+ currents were larger. The efficiency of exocytosis (measured as the Δ Cm jump per total Ca2+ charge influx) was thus significantly lower at night. The paired-pulse ratio remained unchanged, however, suggesting that release probability was not altered. Hence the decreased exocytosis likely reflects a smaller readily releasable vesicle pool at night. Electron microscopy of single sections from intact retinas averaged 65% fewer ribbons at night. Interestingly, the number of active zones did not change from day to night, only the probability of finding a ribbon at an active zone. Additionally, synaptic vesicle halos surrounding the ribbons were more completely filled at night when these on-type bipolar cells are more hyperpolarized. There was no change, however, in the physical dimensions of synaptic ribbons from day to night. These results suggest that the size of the readily releasable vesicle pool and the efficiency of exocytosis are reduced at night when fewer ribbons are present at bipolar cell terminal active zones.

scholarly journals Characterization of a novel large-field cone bipolar cell type in the primate retina: Evidence for selective cone connections

2010 ◽  
Vol 28 (1) ◽  
pp. 29-37 ◽  
Author(s):  
HANNAH R. JOO ◽  
BETH B. PETERSON ◽  
TONI J. HAUN ◽  
DENNIS M. DACEY
Keyword(s):  
Giant Cell ◽  
Bipolar Cell ◽  
Visual Information ◽  
Dendritic Tree ◽  
Cell Types ◽  
Giant Cells ◽  
Bipolar Cells ◽  
Large Field ◽  
Inner Plexiform Layer ◽  
Dendritic Field

AbstractParallel processing of visual information begins at the first synapse in the retina between the photoreceptors and bipolar cells. Ten bipolar cell types have been previously described in the primate retina: one rod and nine cone bipolar types. In this paper, we describe an 11th type of bipolar cell identified in Golgi-stained macaque retinal whole mount and vertical section. Axonal stratification depth, in addition to dendritic and axonal morphology, distinguished the “giant” cell from all previously well-recognized bipolar cell types. The giant bipolar cell had a very large and sparsely branched dendritic tree and a relatively large axonal arbor that costratified with the DB4 bipolar cell near the center of the inner plexiform layer. The sparseness of the giant bipolar’s dendritic arbor indicates that, like the blue cone bipolar, it does not contact all the cones in its dendritic field. Giant cells contacting the same cones as midget bipolar cells, which are known to contact single long-wavelength (L) or medium-wavelength (M) cones, demonstrate that the giant cell does not exclusively contact short-wavelength (S) cones and, therefore, is not a variant of the previously described blue cone bipolar. This conclusion is further supported by measurement of the cone contact spacing for the giant bipolar. The giant cell contacts an average of about half the cones in its dendritic field (mean ± s.d. = 52 ± 17.6%; n = 6), with a range of 27–82%. The dendrites from single or neighboring giant cells that converge onto the same cones suggest that the giant cell may selectively target a subset of cones with a highly variable local density, such as the L or M cones.

Rod bipolar cells in the cone-dominated retina of the tree shrew Tupaia belangeri

1991 ◽  
Vol 6 (6) ◽  
pp. 629-639 ◽  
Author(s):  
Brigitte Müller ◽  
Leo Peichl
Keyword(s):  
Bipolar Cell ◽  
Tree Shrew ◽  
Light And Electron Microscopy ◽  
Plexiform Layer ◽  
Bipolar Cells ◽  
Peripheral Retina ◽  
Inner Plexiform Layer ◽  
Cat Retina ◽  
Topographical Distribution ◽  
Rod Bipolar Cells

AbstractThe tree shrew has a cone-dominated retina with a rod proportion of 5%, in contrast to the common mammalian pattern of rod-dominated retinae. As a first step to elucidate the rod pathway in the tree shrew retina, we have demonstrated the presence of rod bipolar cells and studied their morphology and distribution by light and electron microscopy.Rod bipolar cells were labeled with an antiserum against the protein kinase C (PKC), a phosphorylating enzyme. Intense PKC immunoreactivity was found in perikarya, axons, and dendrites of rod bipolar cells. The cell bodies are located in the sclerad part of the inner nuclear layer, the dendrites ascend to the outer plexiform layer where they are postsynaptic to rod spherules, and an axon descends towards the inner plexiform layer (IPL). The axons branch, and terminate in the vitread third of the IPL where mammalian rod bipolar cells are known to terminate. Two amacrine cell processes are always seen as the postsynaptic elements (dyads). Dendritic and axonal arbors of rod bipolar cells are rather large, up to 100 μm in diameter. The topographical distribution of the rod bipolar cells was analyzed quantitatively in tangential sections.Their density ranges from 300 cells/mm2 in peripheral retina to 900 cells/mm2 more centrally. The distribution is rather flat with no local extremes. Consistent with the low rod proportion in tree shrew, the rod bipolar cell density is low compared to the rod-dominated cat retina for example (36,000-47,000 rod bipolar cells/mm2). Rod-to-rod bipolar cell ratios in the tree shrew retina range from smaller than 1 to about 7, and thus are also lower than in cat.

GABA- and glycine-activated currents in the rod bipolar cell of the rabbit retina

1995 ◽  
Vol 74 (2) ◽  
pp. 856-875 ◽  
Author(s):  
M. A. Gillette ◽  
R. F. Dacheux
Keyword(s):  
Gabaa Receptor ◽  
Bipolar Cell ◽  
Reversal Potential ◽  
Outward Current ◽  
Bipolar Cells ◽  
Morphological Identification ◽  
Response Curves ◽  
Patch Clamp Technique ◽  
T Distribution ◽  
Rod Bipolar Cells

1. Voltage- and ligand-gated currents were recorded from solitary rabbit rod bipolar cells using the whole cell patch-clamp technique. The rod bipolar cell forms a single, stereotypical physiological and morphological class of cells that was easily identified from other neurons and support cells after enzymatic and mechanical dissociation from isolated retina. Protein kinase C immunoreactivity confirmed the validity of using a purely morphological identification of this cell type. 2. Voltage steps in 15-mV increments from a holding potential of -45 mV elicited a large outward current activated near -30 mV. These voltage-gated currents were eliminated by using equimolar substitutions of Cs+ and tetraethylammonium+ for K+ in the pipette, indicating that they represent a mixture of K+ currents. 3. The putative inhibitory neurotransmitters gamma-aminobutyric acid (GABA) and glycine activated inward Cl- currents when pressure-applied from pipettes placed near the axon terminals of rod bipolar cells, which were voltage-clamped at -45 mV. With changes in intracellular or extracellular Cl- concentration, the reversal potential of these ligand-gated currents changed as predicted by the Nernst equation for Cl- activity. The dose-response curves for GABA and glycine were sigmoidal with saturating concentrations of 100 and 300 microM, respectively. 4. GABA-activated currents were 1) reversibly reduced by the allosteric inhibitor picrotoxin and the competitive antagonist bicuculline; 2) potentiated by the benzodiazepine diazepam and the barbiturate barbital sodium; and 3) indistinguishable from muscimol-activated currents. There was no response to the GABAB agonist baclofen. Collectively, these data strongly suggest that the GABA-activated currents in rabbit rod bipolar cells are mediated by the GABAA receptor. This is similar to the GABA-activated currents in other mammalian rod bipolar cells. 5. Application of the conformationally restricted GABA analogue cis-4-aminocrotonic acid (CACA) failed to elicit a response, whereas the conformationally extended GABA analogue trans-4-aminocrotonic acid (TACA) elicited a response similar to that of GABA. Although bicuculline appeared to suppress the GABA-activated current slightly more than the TACA-activated current (not significant using Student's t-distribution), GABA- and TACA-activated currents were equally suppressed by picrotoxin and equally enhanced by diazepam and barbital sodium. These data, coupled with the inefficacy of CACA, argue against the existence of a GABAC-type channel in the rod bipolar cell of the rabbit and suggest that GABA and TACA were activating the same GABAA receptor-channel complex.(ABSTRACT TRUNCATED AT 400 WORDS)

Inhibitory Feedback Shapes Bipolar Cell Responses in the Rabbit Retina

2007 ◽  
Vol 98 (6) ◽  
pp. 3423-3435 ◽  
Author(s):  
Alyosha Molnar ◽  
Frank Werblin
Keyword(s):  
Bipolar Cell ◽  
Light Response ◽  
Bipolar Cells ◽  
Inhibitory Input ◽  
Rabbit Retina ◽  
Cell Responses ◽  
Inhibitory Feedback ◽  
Glycinergic Inhibition ◽  
Rod Bipolar Cells ◽  
Cone Bipolar Cells

Retinal bipolar cells can be divided into on and off types based on the polarity of their response to light. Bipolar activity is further shaped by inhibitory inputs, characterized here by the events that occur immediately after the onset of a light step: 1) in most off bipolar cells, excitatory current decreased, whereas inhibitory current increased. These currents reinforced each other, enhancing the light response. 2) In about half of the on cone bipolar cells, the excitatory current increased, whereas inhibitory current decreased, also reinforcing the light response. Both of these reinforcing interactions were mediated by glycinergic inhibition. 3) In the remaining on cone bipolar cells, excitation and inhibition both increased, but inhibition was delayed so that these cells responded transiently. 4) Finally, in rod bipolar cells, excitation and inhibition both increased so that inhibition suppressed excitation, reducing the light response at all time scales. The suppressive inhibition seen in on cone and rod bipolar cells was mediated by GABA. Thus morphologically diverse bipolar cells receive only four main types of inhibitory input, and the majority of “inhibitory” inputs actually serve to enhance excitation.

scholarly journals Pharmacology of the skate electroretinogram indicates independent ON and OFF bipolar cell pathways.

1996 ◽  
Vol 107 (4) ◽  
pp. 535-544 ◽  
Author(s):  
R L Chappell ◽  
F J Rosenstein
Keyword(s):  
Bipolar Cell ◽  
Visual Information ◽  
Plexiform Layer ◽  
Bipolar Cells ◽  
Inner Plexiform Layer ◽  
Critical Feature ◽  
Single Class ◽  
Afferent Pathways ◽  
Afferent Information ◽  
On And Off Pathways

Organization of afferent information into parallel ON and OFF pathways is a critical feature of the vertebrate visual system. All afferent visual information in the vertebrate retina reaches the inner plexiform layer (IPL) via bipolar cells. It is at the bipolar cell level that separation of ON and OFF information first appears for afferent information from cones. This may also hold true for the rod pathway of cold-blooded vertebrates, but not for mammals. The all-rod retina of the skate presents an opportunity to examine such pathways in a retina having but a single class of photoreceptor. Immunocytochemical evidence suggests that both ON and OFF bipolar cells are present in the skate retina. We examined the pharmacology of the skate electroretinogram (ERG) to test the hypothesis that independent ON and OFF bipolar cell pathways are functional as rod afferent pathways from outer to inner plexiform layer in the skate. 100 microM 2-amino-4-phosphonobutyric acid (APB) reversibly blocked the skate ERG b-wave. A small d-wave-like OFF component of the ERG revealed by DC recording of response to a prolonged (10 s) flash of light was reduced or blocked by 5 mM kynurenic acid (KYN). We found that addition of 200 microM picrotoxin to the Ringer's solution revealed prominent ON and OFF components of the skate ERG while reducing the c-wave. These ON and OFF components were reversibly blocked by 100 microM APB and 5 mM KYN, respectively. Reversible block of the OFF component by KYN was also accomplished in the presence of 500 microM N-methyl-DL-aspartate. From these findings, we conclude that ON and OFF bipolar cells are likely to be functional as parallel afferent interplexiform pathways in the all-rod retina of the skate.

scholarly journals Differential expression of PKCα and -β in the zebrafish retina

2018 ◽  
Author(s):  
Marion F. Haug ◽  
Manuela Berger ◽  
Matthias Gesemann ◽  
Stephan C. F. Neuhauss
Keyword(s):  
Bipolar Cell ◽  
Visual Information ◽  
Neural Circuit ◽  
Ganglion Cells ◽  
Immunohistochemical Analysis ◽  
Cell Types ◽  
Bipolar Cells ◽  
Retinal Ganglion ◽  
Retinal Tissue ◽  
Kinase C

AbstractThe retina is a complex neural circuit in which visual information is transmitted and processed from light perceiving photoreceptors to projecting retinal ganglion cells. Much of the computational power of the retina rests on signal integrating interneurons, such as bipolar cells in the outer retina. While mammals possess about 10 different bipolar cell types, zebrafish (Danio rerio) has at least six ON-type, seven OFF-type, and four mixed-input bipolar cells. Commercially available antibodies against bovine and human conventional protein kinase C (PKC) α and -β are frequently used as markers for retinal ON-bipolar cells in different species, despite the fact that it is not known which bipolar cell subtype(s) they actually label.Moreover, the expression pattern of the five prkc genes (coding for PKC proteins) has not been systematically determined. While prkcg is not expressed in retinal tissue, the other four prkc (prkcaa, prkcab, prkcba, prkcbb) transcripts were found in different parts of the inner nuclear layer and some as well in the retinal ganglion cell layer.Immunohistochemical analysis in adult zebrafish retina using PKCα and PKCβ antibodies showed an overlapping immunolabeling of ON-bipolar cells that are most likely of the BON s6L or RRod type and of the BON s6 type. However, comparison of transcript expression with immunolabling, implies that these antibodies are not specific for one single zebrafish conventional PKC, but rather detect a combination of PKC -α and -β variants.

scholarly journals Different types of retinal inhibition have distinct neurotransmitter release properties

2015 ◽  
Vol 113 (7) ◽  
pp. 2078-2090 ◽  
Author(s):  
Johnnie M. Moore-Dotson ◽  
Justin S. Klein ◽  
Reece E. Mazade ◽  
Erika D. Eggers
Keyword(s):  
Bipolar Cell ◽  
Neurotransmitter Release ◽  
Amacrine Cell ◽  
Glutamate Release ◽  
Amacrine Cells ◽  
Gaba Release ◽  
Bipolar Cells ◽  
Glycine Release ◽  
Presynaptic Mechanisms ◽  
Rod Bipolar Cells

Neurotransmitter release varies between neurons due to differences in presynaptic mechanisms such as Ca2+ sensitivity and timing. Retinal rod bipolar cells respond to brief dim illumination with prolonged glutamate release that is tuned by the differential release of GABA and glycine from amacrine cells in the inner retina. To test if differences among types of GABA and glycine release are due to inherent amacrine cell release properties, we directly activated amacrine cell neurotransmitter release by electrical stimulation. We found that the timing of electrically evoked inhibitory currents was inherently slow and that the timecourse of inhibition from slowest to fastest was GABAC receptors > glycine receptors > GABAA receptors. Deconvolution analysis showed that the distinct timing was due to differences in prolonged GABA and glycine release from amacrine cells. The timecourses of slow glycine release and GABA release onto GABAC receptors were reduced by Ca2+ buffering with EGTA-AM and BAPTA-AM, but faster GABA release on GABAA receptors was not, suggesting that release onto GABAA receptors is tightly coupled to Ca2+. The differential timing of GABA release was detected from spiking amacrine cells and not nonspiking A17 amacrine cells that form a reciprocal synapse with rod bipolar cells. Our results indicate that release from amacrine cells is inherently asynchronous and that the source of nonreciprocal rod bipolar cell inhibition differs between GABA receptors. The slow, differential timecourse of inhibition may be a mechanism to match the prolonged rod bipolar cell glutamate release and provide a way to temporally tune information across retinal pathways.

Somatostatin inhibits calcium influx into rat rod bipolar cell axonal terminals

2001 ◽  
Vol 18 (1) ◽  
pp. 101-108 ◽  
Author(s):  
JULIETTE JOHNSON ◽  
MICHAEL L. CARAVELLI ◽  
NICHOLAS C. BRECHA
Keyword(s):  
Bipolar Cell ◽  
Channel Blocker ◽  
Calcium Influx ◽  
Imaging Techniques ◽  
Amacrine Cells ◽  
Bipolar Cells ◽  
Inhibitory Peptide ◽  
Intracellular Ca ◽  
Indicator Dye ◽  
Rod Bipolar Cells

In the retina, somatostatin (SST), an inhibitory peptide that influences neuronal activity, is predominantly expressed by sparsely occurring amacrine cells. The SST subtype 2A receptor is expressed by rod bipolar cells, including their axonal terminals. We used Ca2+-imaging techniques and the ratiometric Ca2+ indicator dye fura-2 AM to investigate Ca2+ dynamics in rod bipolar cell terminals. Depolarization of rod bipolar cells by the addition of high K+ (50 or 100 mM) elicited a sustained increase in [Ca2+]i in rod bipolar terminals that returned to basal levels following K+ removal. The Ca2+ response was dependent on extracellular Ca2+, and was inhibited by the Ca2+ channel blocker Cd2+ and by the selective L-type Ca2+ channel blocker, nimodipine. SST inhibited a K+ depolarization-induced [Ca2+]i response in rod bipolar terminals. This inhibition was observed with 1 nM SST and was maximal with 1 μM SST. These findings indicate that SST may regulate transmitter release from rod bipolar terminals by activating the SST subtype 2A receptor through modulation of intracellular Ca2+.

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