Abstract
Serotonin (5-hydroxytryptamine, 5-HT) is an important biogenic amine that acts as a neural circuit modulator. It is widespread in the central nervous system of insects. However, little is known about the distribution of serotonin in the nervous system of the cotton bollworm Helicoverpa armigera. In the present study, we performed immunohistochemical experiments with anti-serotonin serum to examine the distribution of serotonin in the central nervous system of H. armigera larvae. We found about 40 serotonin-immunoreactive neurons in the brain and about 20 in the gnathal ganglion. Most of these neurons are wide-field neurons giving rise to processes throughout the neuropils of the brain and the gnathal ganglion. In the central brain, serotonin-immunoreactive processes are present bilaterally in the tritocerebrum, the deutocerebrum, and major regions of the protocerebrum, including the central body (CB), lateral accessory lobes (LALs), clamps, crepine, superior protocerebrum, and lateral protocerebrum. The CB, anterior ventrolateral protocerebrum (AVLP), and posterior optic tubercle (POTU) contain extensive serotonin-immunoreactive process terminals. However, the regions of mushroom bodies, the lateral horn, and protocerebral bridges (PBs) are devoid of serotonin-immunoreactivity. In the gnathal ganglion, the serotonin-immunoreactive processes are also widespread throughout the neuropil, and some process projections extend to the tritocerebrum. Our results provide the first comprehensive description of the serotonergic neuronal network in H. armigera larvae, and they reveal the neural architecture and the distribution of neural substances, allowing us to explore the neural mechanisms of behaviors by using electrophysiological and pharmacological approaches on the target regions.
Highlights
Serotonin (5-hydroxytryptamine, 5-HT) is a biogenic amine that is widely present in both invertebrate and vertebrate animal species (Vleugels et al, 2015)
Antiserum against serotonin has been available for three decades, and the immunohistochemical experiments to Serotonin Neurons in H. armigera Larvae investigate the distribution of serotonin in the nervous system have been performed in a large number of insect species, including locusts, mantes, cockroaches, bugs, beetles, ants, wasps, bees, flies, mosquitoes, and moths (Bishop and O’Shea, 1983; Tyrer et al, 1984; Lange et al, 1988; Nässel, 1988; Homberg and Hildebrand, 1989a,b; Breidbach, 1990; Boleli and PaulinoSimões, 1999; Leitinger et al, 1999; Settembrini and Villar, 2004; Dacks et al, 2006; Liu et al, 2011; Huser et al, 2012; van der Woude and Smid, 2017)
We provide the first comprehensive description of the serotonergic neuronal network in H. armigera larvae, which is the basic knowledge about the neural architecture and the distribution of neural substance and improves our understanding of the neural mechanism of behaviors, such as, host selection, navigation, and feeding preference and plasticity
Summary
Serotonin (5-hydroxytryptamine, 5-HT) is a biogenic amine that is widely present in both invertebrate and vertebrate animal species (Vleugels et al, 2015). Behavioral and gustatory electrophysiological studies revealed that feeding experiences could induce changes in feeding preference of H. armigera for host plants (Zhou et al, 2010; Ma et al, 2016; Wang et al, 2017). Such feeding preference and plasticity is mediated by the signal transduction of the gustatory pathway and the modulation of the neural substance in the central nervous system (Glendinning et al, 1999, 2001). To date little is known about the neural substances in the nervous system of H. armigera
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
