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γ‐Aminobutyric acid (GABA) signaling components in Drosophila : Immunocytochemical localization of GABA B receptors in relation to the GABA A receptor subunit RDL and a vesicular GABA transporter
Author(s) -
Enell Lina,
Hamasaka Yasutaka,
Kolodziejczyk Agata,
Nässel Dick R.
Publication year - 2007
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.21472
Subject(s) - gabaergic , biology , gabaa receptor , glutamate decarboxylase , inhibitory postsynaptic potential , neurotransmission , mushroom bodies , gamma aminobutyric acid , gaba receptor , microbiology and biotechnology , protein subunit , gaba transporter , receptor , immunocytochemistry , neuroscience , biochemistry , drosophila melanogaster , endocrinology , gene , enzyme
γ‐Aminobutyric acid (GABA) is a major inhibitory neurotransmitter in insects and is widely distributed in the central nervous system (CNS). GABA acts on ion channel receptors (GABA A R) for fast inhibitory transmission and on G‐protein‐coupled ones (GABA B R) for slow and modulatory action. We used immunocytochemistry to map GABA B R sites in the Drosophila CNS and compared the distribution with that of the GABA A R subunit RDL. To identify GABAergic synapses, we raised an antiserum to the vesicular GABA transporter (vGAT). For general GABA distribution, we utilized an antiserum to glutamic acid decarboxylase (GAD1) and a gad1 ‐GAL4 to drive green fluorescent protein. GABA B R‐immunoreactive (IR) punctates were seen in specific patterns in all major neuropils of the brain. Most abundant labeling was seen in the mushroom body calyces, ellipsoid body, optic lobe neuropils, and antennal lobes. The RDL distribution is very similar to that of GABA B R‐IR punctates. However, the mushroom body lobes displayed RDL‐IR but not GABA B R‐IR material, and there were subtle differences in other areas. The vGAT antiserum labeled punctates in the same areas as the GABA B R and appeared to display presynaptic sites of GABAergic neurons. Various GAL4 drivers were used to analyze the relation between GABA B R distribution and identified neurons in adults and larvae. Our findings suggest that slow GABA transmission is very widespread in the Drosophila CNS and that fast RDL‐mediated transmission generally occurs at the same sites. J. Comp. Neurol. 505:18–31, 2007. © 2007 Wiley‐Liss, Inc.