Immunocytochemical mapping of an RDL-Like GABA receptor subunit and of GABA in brain structures related to learning and memory in the cricket Acheta domesticus

The distribution of putative RDL-like GABA receptors and of gamma-aminobuty ric acid (GABA) in the brain of the adult house cricket Acheta domesticus w as studied using specific antisera, Special attention was given to brain st ructures known to be related to learning and memory. The main immunostainin g for the RDL-like GABA receptor was observed in mushroom bodies, in partic ular the upper part of mushroom body peduncle and the two arms of the poste rior calyx, Weaker immunostaining was detected in the distal part of the pe duncle and in the alpha and beta lobes, The dorso- and ventrolateral protoc erebrum neuropils appeared rich in RDL-like GABA receptors, Staining was al so detected in the glomeruli of the antennal lobe, as well as in the ellips oid body of the central complex. Many neurons clustered in groups exhibit G ABA-like immunoreactivity. Tracts that were strongly immunostained innervat ed both the calyces and the lobes of mushroom bodies. The glomeruli of the antennal lobe, the ellipsoid body, as well as neuropils of the dorso- and v entrolateral protocerebrum were also rich in GABA-like immunoreactivity, Th e data demonstrated a good correlation between the distribution of the GABA -like and of the RDL-like GABA receptor immunoreactivity, The prominent dis tribution of RDL-like GABA receptor subunits, in particular areas of mushro om bodies and antennal lobes, underlines the importance of inhibitory signa ls in information processing in these major integrative centers of the Inse ct brain.