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Immunocytochemical localization of GABA A receptors in goldfish and chicken retinas
Author(s) -
Yazulla Stephen,
Studholme Keith M.,
Vitorica Javier,
De Blas Angel L.
Publication year - 1989
Publication title -
journal of comparative neurology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.855
H-Index - 209
eISSN - 1096-9861
pISSN - 0021-9967
DOI - 10.1002/cne.902800103
Subject(s) - muscimol , inner plexiform layer , gabaa receptor , retina , gabaergic , biology , amacrine cell , biophysics , receptor , gaba receptor , endocrinology , medicine , anatomy , microbiology and biotechnology , neuroscience , biochemistry
A monoclonal antibody (mAb 62–3G1) to the GABA A receptor/benzodiazepine receptor/Cl − channel complex from bovine brain was used with light and electron microscopy in goldfish retina and light microscopy in chicken retina to localize GABA A receptor immunoreactivity (GABAr‐IR). GABAr‐IR was found in the outer plexiform layer (OPL) in both species, in three broad bands in the inner plexiform layer (IPL) of goldfish, and in seven major bands of the chicken IPL. A small percentage of amacrine cell bodies (composing at least three types) were stained in chicken. In goldfish OPL, GABAr‐IR was localized intracellularly and along the plasma membrane of cone pedicles, whereas rod spherules were lightly stained, but always only intracellularly. In chicken, all three sublayers of the OPL were GABAr‐IR. The presence of GABAr‐IR on photoreceptor terminals is consistent with data indicating feedback from GABAergic horizontal cells to cones. In the goldfish IPL, GABAr‐IR was localized to postsynaptic sites of amacrine cell synapses; intracellular staining of processes in the IPL also was observed in presumed “GABAergic” targets. A comparison of GABAr‐IR with the distributions of 3 H‐muscimol uptake/binding, glutamate decarboxylase‐IR, GABA‐IR, and 3 H‐GABA uptake in the IPL showed either a reasonable correspondence or mismatch, depending on the marker, species, and lamina within the IPL. The distribution of GABAr‐IR in the retina corresponded better with the 3 H‐muscimol than with 3 H‐benzodiazepine binding patterns yet overall was in excellent agreement with many other physiological and anatomical indicators of GABAergic function. We suggest that intracellular GABAr‐IR represents the biosynthetic and/or degradative pathway of the receptor and we conclude that mAb 62–3G1 is a valid marker of GABA A receptors in these retinas and will serve as a useful probe with which to address the issue of mismatches between the localization of GABA A receptors and indicators of presynaptic GABAergic terminals.