Distribution of GABA-like immunoreactive neurons in insects suggests lineage homology

✍ Scribed by Witten, J.L.; Truman, J.W.

• Publisher: John Wiley and Sons
• Year: 1998
• Tongue: English
• Weight: 514 KB
• Volume: 398
• Category: Article
• ISSN: 0021-9967
• DOI: 10.1002/(sici)1096-9861(19980907)398:4<515::aid-cne4>3.0.co;2-5

✦ Synopsis

␥-Aminobutyric acid (GABA) is an important inhibitory neurotransmitter in vertebrates and invertebrates (Sattelle [1990] Adv. Insect Physiol. 22:1-113). The GABA phenotype is lineally determined in postembryonic neurons in the tobacco hawkmoth, Manduca sexta (Witten and Truman, [1991] J. Neurosci. 11:1980 and is restricted to six identifiable postembryonic lineages in the moth's thoracic hemiganglia. We used a comparative approach to determine whether this distinct clustering of GABAergic neurons is conserved in Insecta. In the nine orders of insects surveyed (Thysanura, Odonata, Orthoptera, Isoptera, Hemiptera, Coleoptera, Diptera, Lepidoptera, and Hymenoptera), GABA-like immunoreactive neurons within a thoracic hemiganglion were clustered into six distinct groups that occupied positions similar to the six postembryonic lineages in Manduca. On the basis of cell body position and axon trajectories, we suggest that these are indeed homologous lineage groups and that the lineal origins of the GABAergic cells have been very conservative through insect evolution. The distinctive clustering of GABA-positive cells is shared with crustaceans (Mulloney and