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Specific cell types in cat retina express different forms of glutamic acid decarboxylase
Author(s) -
Vardi Noga,
Auerbach Peter
Publication year - 1995
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.903510305
Subject(s) - glutamate decarboxylase , amacrine cell , retina , inner plexiform layer , gabaergic , biology , immunocytochemistry , neuroscience , neurotransmitter , cell type , dopamine , glutamate receptor , microbiology and biotechnology , cell , endocrinology , biochemistry , central nervous system , enzyme , inhibitory postsynaptic potential , receptor
We studied the expression of glutamate decarboxylase (GAD), GAD65 and GAD67, in cat retina by immunocytochemistry. About 10% of GABAergic amacrime cells express only GAD65 and 30% express only GAD67. Rougly 60% contain both forms of the enzyme, but GAD67 is present only at low levels in the majority of these double‐labeled amacrine cells. The staining pattern in the inner plexiform layer (IPL) for the two GAD forms was also different. GAD65 was restricted to strata 1–4, and GAD67 was apparent throughout the IPL but was strongest in strata 1 and 5. This indicates that soams, as well as their processes, are differentially stained for the two forms of GAD. Cell types expressing only GAD65 include interplexiform cells, one type of cone bipolar cell, and at least one type of serotonin‐accumulating amacrine cell. Cell types expressing only GAD67 include amacrine cells synthesizing dopamine, amacrine cells synthesizing nitric oxide (NO), and amacrine cells accumulating serotonin. Cholinergic amacrine cells express a low level of both GAD forms. Our findings in the retina are consistent with previous observations in the brain that GAD65 expression is greater in terminals than in somas. In addition, in retina most neurons expressing GAD67 also contain a second neurotransmitter as well as GABA, and they tend to be larger than neurons expressing GAD65. We propose that large cells have a greater demand for GABA than small cells, and thus require the constant, relatively unmodulated level of GABA that is provided by GAD67. © 1995 Willy‐Liss, Inc.