Neuropeptides in the antennal lobe of the yellow fever mosquito, Aedes aegypti.
Bottom Line: The most diverse and versatile neurochemicals in the insect nervous system are found in the neuropeptides.Allatostatin A, allatotropin, SIFamide, FMRFamide-related peptides, short neuropeptide F, myoinhibitory peptide, and tachykinin-related peptides were found to be expressed in local interneurons and extrinsic neurons of the antennal lobe.Building on these results, we discuss the possible role of neuropeptide signaling in the antennal lobe of Ae. aegypti.
Affiliation: Unit of Chemical Ecology, Department of Plant Protection Biology, Swedish University of Agricultural Sciences, 230 53, Alnarp, Sweden.Show MeSH
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Mentions: FMRFamide immunoreactivity was observed in 15–20 LNs with cell bodies located lateral to the AL (Figs. 5, 7E). These neurons supplied innervation to all glomeruli and the Johnston’s organ center of the AL (Figs. 5, 6), and did not give rise to any apparent processes outside the AL. We observed a dense innervation of the anteromedial (AM1–5), anterodorsal (AD2–4), and anterolateral (AL1) glomeruli, as well as of a ventral glomerulus (V4) (Fig. 6). Moreover, FMRFamide immunoreactivity was observed in a pair of extrinsic neurons, one in each hemisphere, which innervated the ALs and had widefield innervation in distinct neuropil areas of the protocerebrum (Fig. 7). These neurons innervated the ALs sparsely with thick processes with large varicosities (Fig. 7A,B). Innervation by these processes was restricted to the posterior and lateral portions of the AL and was extraglomerular (Fig. 7A,B). Varicose fibers, however, wrapped around the maxillary-palp-associated glomerulus, MD1 (Fig. 7A; Ignell et al., 2005). The axons of these neurons exited the ALs anterolaterally and then projected medially through the lateral accessory lobe (LAL) to the level of the central complex (CC) (Fig. 7B–E). At this level, the axon of each neuron bifurcated, and one branch projected anteriorly, parallel with the inner antennocerebral tract (IACT) (Fig. 7D,E). This axonal branch displayed further branching shortly after the bifurcation, and each of these branches projected into the superior protocerebrum (Fig. 7D,E); we were unable to trace the full extension of these branches in the protocerebrum. The second branch extended medially, sending a bundle of fibers into the fan-shaped body of the CC (Fig. 7D,E), invading it by densely packed arborizations. Parallel to the axon exiting from the AL, we observed a single varicose fiber that innervated both the LAL and the ventral body of the CC (Fig. 7E).
Affiliation: Unit of Chemical Ecology, Department of Plant Protection Biology, Swedish University of Agricultural Sciences, 230 53, Alnarp, Sweden.