Rapid glutamatergic alterations in the neural retina induced by retinal detachment.
OBJECTIVE
Retinal detachment induces neurochemical changes in the neural retina over a span of days to weeks. However, little information is available on the acute response in the retina to detachment.


METHODS
Distribution of the neurotransmitters glutamate, glycine, and gamma-aminobutyric acid (GABA) and the metabolic amino acids aspartate and glutamine was examined immunocytochemically from 5 to 30 minutes and at 3 hours after retinal detachment in a salamander eyecup preparation.


RESULTS
Glutamate showed a rapid depletion from neuronal cell bodies in detached retina, whereas Müller cells, which normally sequester and metabolize glutamate, showed increased immunolabeling for glutamine. Changes occurred exclusively in detached retinal regions of the eyecup. Aspartate, a precursor for glutamate synthesis, also showed decreased labeling in neuronal cell bodies in detached retinal regions, although these changes were not as striking as those observed for glutamate. In contrast, the distributions of the inhibitory amino acid neurotransmitters glycine and GABA were not affected appreciably by acute retinal detachment.


CONCLUSIONS
These results indicate that retinal detachment induces rapid, localized alterations in the glutamatergic system of the neural retina that are consistent with a massive efflux of neuronal glutamate and concomitant alterations in glutamate metabolism. An acute efflux of neuronal glutamate in detached retina could contribute to excitotoxicity and to the initiation of structural alterations and changes in gene expression; it is also consistent with reported neurochemical changes associated with longer term retinal detachment.
College of Optometry, University of Houston, Texas 77204, USA. dsherry@mail-gw.opt.uh.edu
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DM
Sherry
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Townes-Anderson
D000557:Ambystoma; D000818:Animals; D001224:Aspartic Acid / Q000378:metabolism; D019084:Fluorescent Antibody Technique, Indirect; D018698:Glutamic Acid / Q000378:metabolism; D005998:Glycine / Q000378:metabolism; D007091:Image Processing, Computer-Assisted; D007124:Immunoenzyme Techniques; D018377:Neurotransmitter Agents / Q000378:metabolism*; D011817:Rabbits; D012160:Retina / Q000378:metabolism* / Q000473:pathology; D012163:Retinal Detachment / Q000378:metabolism* / Q000473:pathology; D005680:gamma-Aminobutyric Acid / Q000378:metabolism
D018377:Neurotransmitter Agents; D001224:Aspartic Acid; D018698:Glutamic Acid; D005680:gamma-Aminobutyric Acid; D005998:Glycine