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: 9.67). 12/1988; 85(21):8321-5. DOI: 10.1073/pnas.85.21.8321
Source: PubMed


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.
    Full-text · Article · Jan 2011 · Journal of Molecular Neuroscience
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    • "In the retina, the visual information is transmitted vertically by glutamate containing cells, photoreceptors, bipolar and ganglion cells [45,46,47,48,49] and from the retina to the LGN and visual cortex. The fact that expression of NMDA receptor subunits in the retina can be altered leads us to suggest that the activity-dependent expression of NMDA receptors in the visual cortex or LGN could be co-incident with, or perhaps even dependent on the changes that occur in the retina. "
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    ABSTRACT: The expression of retinal CaMKII is up-regulated in the retina of the rdta mouse in which rod photoreceptors are genetically ablated. As ionotropic glutamate receptors are known substrates of CAMKII, this study set out to determine if the protein levels of ionotropic glutamate receptors in the rdta mouse retina are also affected. The NMDA receptor subunits (NR1, NR2A/B) and the GluR1; AMPA receptor subunit (GluR1) were examined in immunolabeled western blots. The results demonstrate that the amounts of NR1 and NR2A/B receptor subunits are significantly increased in crude synaptic membrane fractions isolated from retinae of the rdta mice when compared to their normal, littermate controls. The GluR1 receptor subunit and its phosphorylation are simultaneously increased in retinae of the rdta mice. These data indicate that the NMDA receptors and AMPA (GluR1) receptors are altered in the retinae of rdta mice that lack rod photoreceptors. Because the rods are lost at an early stage in development, it is likely that these results are indicative of synaptic reorganization in the retina.
    Preview · Article · Feb 2001 · BMC Neuroscience
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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.
    Preview · Article · Dec 1999 · Vision Research
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