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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
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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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    • "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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    • "(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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