Differential Synaptic Localization of Two Major $\gamma $-aminobutyric Acid Type A Receptor $\alpha $ Subunits on Hippocampal Pyramidal Cells

• Published in: Proceedings of the National Academy of Sciences - PNAS Vol. 93; no. 21; pp. 11939 - 11944
• Main Authors: Nusser, Zoltan, Sieghart, Werner, Benke, Dietmar, Fritschy, Jean-Marc, Somogyi, Peter
• Format: Journal Article
• Language: English
• Published: United States National Academy of Sciences of the United States of America 15-10-1996; National Acad Sciences; National Academy of Sciences
• Subjects: Animals; Antibodies; Axons; Axons - metabolism; Axons - ultrastructure; Biology; Dendrites; Dendrites - metabolism; Dendrites - ultrastructure; Hippocampus - metabolism; Immune Sera; Innervation; Interneurons; Macromolecular Substances; Microscopy, Immunoelectron; Neurology; Neurons; Neuroscience; Pyramidal cells; Pyramidal Cells - metabolism; Pyramidal Cells - ultrastructure; Rats; Rats, Wistar; Receptors; Receptors, GABA-A - analysis; Receptors, GABA-A - metabolism; Synapses; Synapses - metabolism; Synapses - ultrastructure
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.93.21.11939

Hippocampal pyramidal cells, receiving domain specific GABAergic inputs, express up to 10 different subunits of the $\gamma $-aminobutyric acid type A (GABA$_{\text{A}}$) receptor, but only 3 different subunits are needed to form a functional pentameric channel. We have tested the hypothesis that some subunits are selectively located at subsets of GABAergic synapses. The $\alpha $1 has been found in most GABAergic synapses on all postsynaptic domains of pyramidal cells. In contrast, the $\alpha $2 subunit was located only in a subset of synapses on the somata and dendrites, but in most synapses on axon initial segments innervated by axo-axonic cells. The results demonstrate that molecular specialization in the composition of postsynaptic GABA$_{\text{A}}$ receptor subunits parallels GABAergic cell specialization in targeting synapses to a specific domain of postsynaptic cortical neurons.