Bipolar cells in the turtle retina are strongly immunoreactive for glutamate. Proceedings

Department of Cellular and Development Biology, Harvard University, Cambridge, MA 02138.
Proceedings of the National Academy of Sciences (Impact Factor: 9.81). 12/1988; 85(21):8321-5. DOI: 10.1073/pnas.85.21.8321
Source: PubMed

ABSTRACT Strong glutamate immunoreactivity was observed by both light and electron microscopy in bipolar cells of the turtle (Pseudemys scripta elegans) retina after postembedding immunohistochemistry. Virtually all bipolar cells showed strong labeling, on average 18 times that of the Müller (glial) cells. The data suggest that both on- and off-center bipolar cells are glutamatergic. Photoreceptors were also labeled, but with a labeling intensity about half that of the bipolar cells. Other types of retinal neurons showed less immunoreactivity, except for a small population of strongly labeled amacrine cells.

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Available from: Jon Storm-Mathisen, Sep 28, 2014
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    • "In the scotopic responses, the amelioration by PACAP was observed both in the a-wave and the b-wave, representing the photoreceptor and the inner retinal function, respectively. Glutamate mediates excitatory synaptic transmission at the photoreceptor/bipolar cells and at the bipolar/ganglion cell synapses (Ehinger et al. 1988). MSG treatment, in accordance with earlier observations, led to a very severe degeneration in the inner retina and less severe degeneration in the photoreceptor layer. "
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    ABSTRACT: Pituitary adenylate cyclase-activating polypeptide (PACAP) and its receptors occur throughout the nervous system, including the retina. PACAP exerts diverse actions in the eye: it influences ocular blood flow, contraction of the ciliary muscle, and has retinoprotective effects. This has been proven in different models of retinal degeneration. The in vivo protective effects of PACAP have been shown in retinal degeneration induced by kainic acid, optic nerve transection and ischemia. We have previously shown by morphological, morphometrical and immunohistochemical analyses that intravitreal PACAP administration protects against monosodium glutamate (MSG)-induced damage in neonatal rats. The question was raised whether these apparent morphological improvements by PACAP administration also lead to functional amelioration in MSG-induced retinal damage. The aim of the present study was to investigate the functional consequences of MSG treatment and the subsequent PACAP administration using electroretinographic measurements. The histological and morphometrical analyses supported the earlier findings that PACAP protected the retina in MSG-induced excitotoxicity. ERG recordings revealed a marked decrease in both the b- and a-wave values, reflecting the function of the inner retinal layers and the photoreceptors, respectively. In retinas receiving intravitreal PACAP treatment, these values were significantly increased. Thus, the functional outcome, although not parallel with the morphology, was significantly improved after PACAP treatment. The present observations are important from the clinical point of view showing, for the first time, that PACAP treatment is able to improve the functional properties of the retina in excitotoxic damage.
    Journal of Molecular Neuroscience 01/2011; 43(1):44-50. DOI:10.1007/s12031-010-9406-1 · 2.76 Impact Factor
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    • "There is broad agreement that bipolar cells in vertebrate retinae are excitatory in nature, and most likely use glutamate as their neurotransmitter (Slaughter & Miller, 1983; Lukasiewicz & McReynolds, 1985; Ehinger, Otterson, Storm-Mathisen & Dowling, 1988; Marc, Liu, Kalloniatis, Raiguel & Van Haesendonck, 1990; Massey, 1990 for review). However, in amphibian retinae, there is a considerable body of neurochemical evidence to support the presence of GABA as a neurotransmitter in some bipolar cells. "
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    ABSTRACT: Our previous work showed that about 12% of bipolar cells in salamander retina synthesize and take up gamma-aminobutyric acid (GABA), are GABA transporter (GAT)-immunoreactive, and respond with a GAT current to extracellularly applied GABA, suggesting that these bipolar cells use GABA, in addition to glutamate, as a neurotransmitter. Further support for this idea was obtained in this study by use of immunogold electron microscopy and whole-cell patch clamp electrophysiology. Ultrastructural analysis showed that amacrine cell and ganglion cell processes were postsynaptic to GABA-immunoreactive synapses made by bipolar cell axon terminals. Whole-cell recordings were obtained from amacrine and ganglion cells in response to activation of bipolar cells by puffing KCl at their dendrites in the outer plexiform layer. Inhibitory postsynaptic currents were observed in several third order neurons, even after blocking the excitatory postsynaptic responses, generated in the inner plexiform layer, with a combined application of NMDA and non-NMDA receptor antagonists, AP-5 and CNQX. These ultrastructural and electrophysiological data support our previous neurochemical results, and suggest that the retinal through-information pathway in salamander includes both inhibitory GABAergic as well as excitatory glutamatergic synaptic mechanisms.
    Vision Research 12/1999; 39(22):3653-61. DOI:10.1016/S0042-6989(99)00112-1 · 2.38 Impact Factor
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    • "(a) Functional polarization of the wide-¢eld, transient amacrine cell While others have reported amacrine cell processes exhibiting a morphology consistent with axonal and dendritic functions (Vaney 1990; Famiglietti 1991, 1992), this is the ¢rst study to demonstrate axons and dendrites in amacrine cells functionally. As shown in ¢gure 4b, the tufted processes of the wide-¢eld, transient amacrine cell, which are located near the soma, are the only regions in the cell sensitive to glutamate or its analogues and, thus, are the only regions of the cell capable of mediating EPSCs because glutamate is the predominant excitatory transmitter at the bipolar to amacrine cell synapse (Ehinger et al. 1988; Marc et al. 1990; Massey & Maguire 1997). "
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    ABSTRACT: The spatial distribution of ion channels within amacrine cells of the tiger salamander retina was studied using patch recording in the retinal slice preparation. By focally puffing kainate, GABA and glycine at amacrine cell processes in the inner plexiform layer, it was determined that the cell's glutamate receptors were located in a confined region of the processes near the soma, while glycine and GABA receptors were located throughout the processes. Likewise, similar techniques in conjunction with voltage steps demonstrated that voltage-gated sodium channels were located throughout the cell and were shown to generate sodium-dependent spikes, while only the processes contained voltage-gated calcium channels. These results suggest that this form of transient amacrine cell collects its excitatory synaptic inputs in a region confined to a central annular region near the soma, that the signal is actively propagated throughout its processes by voltage-gated sodium channels and that calcium-dependent neurotransmitter release of glycine from this neuron can occur throughout its processes. Thus, excitatory signals are collected in the processes near the soma, inhibitory signals throughout the processes and excitation is probably propagated throughout the processes of the amacrine cell.
    Proceedings of the Royal Society B: Biological Sciences 06/1999; 266(1423):987-92. DOI:10.1098/rspb.1999.0734 · 5.29 Impact Factor
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