Immunocytochemistry of GABA in the brain and suboesophageal ganglion ofManduca sexta

Abstract

We have used specific antisera against protein-conjugated gamma-aminobutyric acid (GABA) in immunocytochemical preparations to investigate the distribution of putatively GABAergic neurons in the brain and suboesophageal ganglion of the sphinx moth Manduca sexta. About 20,000 neurons per brain hemisphere exhibit GABA-immunoreactivity. Most of these are optic-lobe interneurons, especially morphologically centrifugal neurons of the lamina and tangential neurons that innervate the medulla or the lobula complex. Many GABA-immunoreactive neurons, among them giant fibers of the lobula plate, project into the median protocerebrum. Among prominent GABA-immunoreactive neurons of the median protocerebrum are about 150 putatively negative-feedback fibers of the mushroom body, innervating both the calyces and lobes, and a group of large, fan-shaped neurons of the lower division of the central body. Several commissures in the supra- and suboesophageal ganglion exhibit GABA-like immunoreactivity. In the suboesophageal ganglion, a group of contralaterally descending neurons shows GABA-like immunoreactivity. The frontal ganglion is innervated by immunoreactive processes from the tritocerebrum but does not contain GABA-immunoreactive somata. With few exceptions the brain nerves do not contain GABA-immunoreactive fibers.

Global and local modulatory supply to the mushroom bodies of the moth Spodoptera littoralis

“…It is of interest that GABA-immunoreactive innervation to the calyces in S. littoralis originates from several different sources: from the protocerebrum entering the calyces via the lateral antennoglomerular tract, from the Y-tract, and from within the lobes and pedunculus. The first type of innervation was previously shown in Manduca sexta, where GABA-immunoreactive neurons innervating the calyx via the inner antennoglomerular tract have dendritic branches in the lateral horn (Homberg et al, 1987 This organization suggests homology with similarly disposed GABA-immunoreactive neurons in cockroaches that mediate odor-evoked feed-forward inhibition to the calyx in that taxon (Strausfeld and Li., 1999); or in locusts, where they are suggested to contribute to signal sparsening in the mushroom body (Perez-Orive et al, 2002).…”

“…Mushroom bodies receive inhibitory and putative modulatory innervation by neurons that are immunoreactive to γ-amino butyric acid (GABA), as well as other amino acids, biogenic amines, and peptides (e.g. Dacks et al, 2005;Homberg et al, 1987;Homberg and Hildebrand, 1989;Homberg et al, 2004;Kim et al, 1998;Sinakevitch et al, 2005). GABA is a major inhibitory neurotransmitter in invertebrates (Kerkut et al, 1969;Usherwood, 1978), having an inhibitory effect at the neuromuscular junctions (Sattelle, 1992;Richmond and Jorgensen, 1999).…”

“…GABA-mediated inhibition is thought to play a role in the processing of olfactory information both at the level of the antennal lobes (Christensen et al, 1998;Sachse and Galizia, 2002;Wilson and Laurent, 2005) and the mushroom bodies (Mizunami et al, 2005;Leitch and Laurent, 1996;Perez-Orive et al, 2002). GABA-immunoreactive neurons supplying terminal processes to the mushroom body calyces originate from dendrites situated either in the mushroom body lobes or in circumscribed regions of the lateral protocerebrum including the lateral horn (Homberg et al, 1987;Yamazaki et al, 1998;Bicker, 1999;Strausfeld and Li, 5 1999;Grünewald, 1999a). These regions receive the telodendria of output neurons from the mushroom body lobes (Strausfeld and Li, 1999).…”

Odorant-induced oscillations in the mushroom bodies of the locust

“…The present results suggest the existence (Schtirmann, 1974(Schtirmann, , 1987, and are excitatory (present results). The Kenyon cells may form lateral chemical synapses with neighboring axons in the peduncle (Schlrmann, 1974) and contact the dendritic endings of "feedback" interneurons in the lobes (Schildberger, 1983(Schildberger, , 1984Gronenberg, 1987;Homberg et al, 1987;Rybak and Menzel, 1993). The putative dynamic polarization of these "feedback" neurons is only inferred from morphological data.…”

Acetylcholine in the crayfish optic lobe: concentration profile and cellular localization

“…These studies have mapped the distribution of enkephalin-like and substance P-like peptides (Mantillas et al,198 1); GABA (Datum et al, 1986;Meyer et al, 1986;Homberg et al, 1987), serotonin (Beltz and Kravitz, 1983;Elofsson, 1983;Nassel et al, 1985), the peptide proctolin (Siwicki and Bishop, 1986), dopamine (Vieillemaringe et al, 1984), choline acetyltransferase (Buchner et al, 1986;Gorczyca and Hall, 1987), and a crustacean peptide hormone (Schueler et al, 1986).…”