Distribution of metabotropic glutamate receptor DmGlu-A in Drosophila melanogaster central nervous system

L-glutamate is the excitatory neurotransmitter at neuromuscular junctions i n insects. It may also be involved in neurotransmission within the central nervous system (CNS), but its function therein remains elusive. The roles o f glutamatergic synapses in the Drosophila melanogaster CNS were investigat ed, with focus on the study of DmGluRA, a G-protein-coupled glutamate recep tor. In a first attempt to determine the function of this receptor, we desc ribe its distribution in the larval and adult Drosophila CNS, using a polyc lonal antibody raised against the C-terminal sequence of the protein. DmGlu RA is expressed in a reproducible pattern both in the larva and in the adul t. In particular, DmGluRA can be found in the antennal lobes, the optic lob es, the central complex, and the median bundle in the adult CNS. However, D mGluRA-containing neurons represented only a small fraction of all CNS neur ons. DmGluRA immunoreactivity was not detected at the larval neuromuscular junction nor in the body wall muscles. The correlations between DmGluRA dis tribution and previously described glutamate-like immunoreactivity patterns , as well as the implications of these observations concerning the possible functions of DmGluRA in the Drosophila CNS, are discussed. J. Comp. Neurol . 438:213-225, 2001. (C) 2001 Wiley-Liss, Inc.