gamma-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.

• 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 (GABAAR) for fast inhibitory transmission and on G-protein-coupled ones (GABABR) for slow and modulatory action. We used immunocytochemistry to map GABABR sites in the Drosophila CNS and compared the distribution with that of the GABAAR 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. GABABR-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 GABABR-IR punctates. However, the mushroom body lobes displayed RDL-IR but not GABABR-IR material, and there were subtle differences in other areas. The vGAT antiserum labeled punctates in the same areas as the GABABR and appeared to display presynaptic sites of GABAergic neurons. Various GAL4 drivers were used to analyze the relation between GABABR 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.

Ämnesord

NATURVETENSKAP  -- Biologi (hsv//swe)

NATURAL SCIENCES  -- Biological Sciences (hsv//eng)

Nyckelord

insect central nervous system;inhibition;G-protein-coupled receptor;ion channel receptor;glutamic acid decarboxylase

Biology

Biologi

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