Strychnine blocks transient but not sustained inhibition in mudpuppy retinal ganglion cells.

Belgum, Jack H.; Dvorak, David R.; McReynolds, John S.

doi:10.1113/jphysiol.1984.sp015375

Cited by 86 publications

(50 citation statements)

References 30 publications

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“…ON-OFF amacrine cells in the amphibian retina generate a strong feedforward inhibition onto ganglion cells; it appears that both GABA and glycinergic subtypes are present (Belgum et al 1984;Deng et al 2001;Miller et al 1977Miller et al , 1981. More recent studies have determined that impulse activity in these cells is required for secretion of inhibitory neurotransmitter for both feedforward (Cook and Werblin 1994;Taylor 1999) and feedback (Shields and Lukasiewicz 2003) inhibition onto bipolar cell terminals.…”

Section: Introductionmentioning

confidence: 99%

Form and Function of on-off Amacrine Cells in the Amphibian Retina

Miller

Staff

Velte

2006

Journal of Neurophysiology

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Miller, Robert F., Nathan P. Staff, and Toby J. Velte. Form and function of ON-OFF amacrine cells in the amphibian retina. J Neurophysiol 95: 3171-3190, 2006. First published February 15, 2006 doi:10.1152/jn.00090.2005. ON-OFF amacrine cells were studied with whole cell recording techniques and intracellular staining methods using intact retina-eyecup preparations of the tiger salamander (Ambystoma tigrinum) and the mudpuppy (Necturus maculosus). Morphological characterization of these cells included three-dimensional reconstruction methods based on serial optical sections obtained with a confocal microscope. Some cells had their detailed morphology digitized with a computer-assisted tracing system and converted to compartmental models for computer simulations. The dendrites of ON-OFF amacrine cells have spines and numerous varicosities. Physiological recordings confirmed that ON-OFF amacrine cells generate both large-and small-amplitude impulses attributed, respectively, to somatic and dendritic generation sites. Using a multichannel model for impulse generation, computer simulations were carried out to evaluate how impulses are likely to propagate throughout these structures. We conclude that the ON-OFF amacrine cell is organized with multifocal dendritic impulse generating sites and that both dendritic and somatic impulse activity contribute to the functional repertoire of these interneurons: locally generated dendritic impulses can provide regional activation, while somatic impulse activity results in rapid activation of the entire dendritic tree.

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Section: Introductionmentioning

confidence: 99%

Form and Function of on-off Amacrine Cells in the Amphibian Retina

Miller

Staff

Velte

2006

Journal of Neurophysiology

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“…Glycinergic inhibition to ganglion cells has two components. One glycinergic input to ganglion cells provides fast, transient IPSPs at the onset and offset of the light response (Belgum et al, 1984). Another glycinergic input is tonic (Miller et al, 1981).…”

Section: Glycine Receptor Subtypes In Retinal Physiologymentioning

confidence: 99%

Partition of Transient and Sustained Inhibitory Glycinergic Input to Retinal Ganglion Cells

Han

Zhang²,

Slaughter³

1997

J. Neurosci.

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Physiological and pharmacological properties of possible subtypes of the native glycine receptor were investigated in retinal neurons using whole-cell voltage-clamp techniques. Two discrete inhibitory glycine responses were identified in ganglion cells. The responses could be distinguished pharmacologically: one was sensitive to strychnine and the other to 5,7-dichlorokynurenic acid. The two responses had different kinetics: the former had a fast onset and fast desensitization, whereas the latter had a slower onset and was much more sustained. The physiological and pharmacological distinctions suggest that the responses are mediated by different receptors. These receptors transduce glycinergic synaptic signals to ganglion cells, where they serve as low-and high-pass filters, respectively, of EPSPs.Key words : glycine receptors; inhibition; strychnine; 5,7-dichlorokynurenic acid; ganglion cells; retina In the vertebrate retina, glycine and GABA share the task of mediating inhibition to ganglion cells. They contribute to the formation of trigger features, such as directional selectivity and edge detection (Caldwell et al., 1978). Several GABA receptor subtypes have been identified and linked to specific aspects of visual information processing Pan and Slaughter, 1991;Zhang and Slaughter, 1995). Although GABAergic and glycinergic neurons are equally populous in the inner retina, a similar diversity of glycinergic receptors has not been described.There is reason to suspect that discrete glycine receptor subtypes exist in retina. Like the GABA receptor, the glycine receptor is a pentamer of ␣ and ␤ subunits in which there are multiple isoforms. In mammalian retina, three ␣ subunit isoforms (␣ 1 , ␣ 2 , ␣ 3 ) have been localized to rat ganglion cells (Greferath et al., 1994). This molecular diversity implies functional and pharmacological variability (Becker, et al., 1988;Betz, 1991;Malosio, 1991a); however, it has proven difficult to translate molecular studies to properties of native glycine receptors or to determine the physiological significance of differential expression.We examined native glycine receptors in isolated amphibian retinal neurons and found that glycine produced two currents: a large, fast, transient, desensitizing component and a smaller, slower, sustained component. Selective antagonists of each of these two currents were identified, implicating two subtypes of the glycine receptor. The agonist and antagonist sensitivities of these two putative receptors were characterized, and their role in synaptic transmission was identified. The results indicate that tonic and phasic glycinergic IPSPs result from two populations of receptor. MATERIALS AND METHODSAnimal experimental preparation. The isolated retinal cell preparation has been described (Bader et al., 1979;Pan and Slaughter, 1995). Briefly, the tiger salamander Ambystoma tigrinum (Kons Scientific, Germantown, WI) was decapitated and pithed, and the eyes were removed. The retina was isolated and incubated for ϳ30 -60 min at room temperature (22...

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“…Glycinergic inhibitory synaptic responses were always blocked with strychnine (2-5 M) (Belgum et al 1984). When indicated, N-methyl-D-aspartate (NMDA) receptors were blocked with D-AP5 (40 M) (Mittman et al 1990).…”

Section: Extracellular Solutionsmentioning

confidence: 99%

Spike-Dependent GABA Inputs to Bipolar Cell Axon Terminals Contribute to Lateral Inhibition of Retinal Ganglion Cells

Shields

Lukasiewicz

2003

Journal of Neurophysiology

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The inhibitory surround signal in retinal ganglion cells is usually attributed to lateral horizontal cell signaling in the outer plexiform layer (OPL). However, recent evidence suggests that lateral inhibition at the inner plexiform layer (IPL) also contributes to the ganglion cell receptive field surround. Although amacrine cell input to ganglion cells mediates a component of this lateral inhibition, it is not known if presynaptic inhibition to bipolar cell terminals also contributes to surround signaling. We investigated the role of presynaptic inhibition by recording from bipolar cells in the salamander retinal slice. TTX reduced light-evoked GABAergic inhibitory postsynaptic currents (IPSCs) in bipolar cells, indicating that presynaptic pathways mediate lateral inhibition in the IPL. Photoreceptor and bipolar cell synaptic transmission were unaffected by TTX, indicating that its main effect was in the IPL. To rule out indirect actions of TTX, we bypassed lateral signaling in the outer retina by either electrically stimulating bipolar cells or by puffing kainate (KA) directly onto amacrine cell processes lateral to the recorded cell. In bipolar and ganglion cells, TTX suppressed laterally evoked IPSCs, demonstrating that both pre- and postsynaptic lateral signaling in the IPL depended on action potentials. By contrast, locally evoked IPSCs in both cell types were only weakly suppressed by TTX, indicating that local inhibition was not as dependent on action potentials. Our results show a TTX-sensitive lateral inhibitory input to bipolar cell terminals, which acts in concert with direct lateral inhibition to give rise to the GABAergic surround in ganglion cells.

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Strychnine blocks transient but not sustained inhibition in mudpuppy retinal ganglion cells.

Cited by 86 publications

References 30 publications

Form and Function of on-off Amacrine Cells in the Amphibian Retina

Form and Function of on-off Amacrine Cells in the Amphibian Retina

Partition of Transient and Sustained Inhibitory Glycinergic Input to Retinal Ganglion Cells

Spike-Dependent GABA Inputs to Bipolar Cell Axon Terminals Contribute to Lateral Inhibition of Retinal Ganglion Cells

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