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Comparative cellular distribution of GABA A and GABA B receptors in the human basal ganglia: Immunohistochemical colocalization of the α 1 subunit of the GABA A receptor, and the GABA B R1 and GABA B R2 receptor subunits
Author(s) -
Waldvogel Henry J.,
Billinton Andy,
White Julia H.,
Emson Piers C.,
Faull Richard L.M.
Publication year - 2004
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.20005
Subject(s) - substantia nigra , globus pallidus , gabaergic , biology , colocalization , medium spiny neuron , pars compacta , basal ganglia , neuroscience , gabaa receptor , striatum , pars reticulata , receptor , dopamine , inhibitory postsynaptic potential , biochemistry , central nervous system , dopaminergic
The GABA B receptor is a G‐protein linked metabotropic receptor that is comprised of two major subunits, GABA B R1 and GABA B R2. In this study, the cellular distribution of the GABA B R1 and GABA B R2 subunits was investigated in the normal human basal ganglia using single and double immunohistochemical labeling techniques on fixed human brain tissue. The results showed that the GABA B receptor subunits GABA B R1 and GABA B R2 were both found on the same neurons and followed the same distribution patterns. In the striatum, these subunits were found on the five major types of interneurons based on morphology and neurochemical labeling (types 1, 2, 3, 5, 6) and showed weak labeling on the projection neurons (type 4). In the globus pallidus, intense GABA B R1 and GABA B R2 subunit labeling was found in large pallidal neurons, and in the substantia nigra, both pars compacta and pars reticulata neurons were labeled for both receptor subunits. Studies investigating the colocalization of the GABA A α 1 subunit and GABA B receptor subunits showed that the GABA A receptor α 1 subunit and the GABA B R1 subunit were found together on GABAergic striatal interneurons (type 1 parvalbumin, type 2 calretinin, and type 3 GAD neurons) and on neurons in the globus pallidus and substantia nigra pars reticulata. GABA B R1 and GABA B R2 were found on substantia nigra pars compacta neurons but the GABA A receptor α 1 subunit was absent from these neurons. The results of this study provide the morphological basis for GABAergic transmission within the human basal ganglia and provides evidence that GABA acts through both GABA A and GABA B receptors. That is, GABA acts through GABA B receptors, which are located on most of the cell types of the striatum, globus pallidus, and substantia nigra. GABA also acts through GABA A receptors containing the α 1 subunit on specific striatal GABAergic interneurons and on output neurons of the globus pallidus and substantia nigra pars reticulata. J. Comp. Neurol. 470:339–356, 2004. © 2004 Wiley‐Liss, Inc.