Development of nitrergic neurons in the nervous system of the locust embryo

Abstract

We followed the development of the nitric oxide-cyclic guanosine monophosphate (NO-cGMP) system during locust embryogenesis in whole mount nervous systems and brain sections by using various cytochemical techniques. We visualized NO-sensitive neurons by cGMP immunofluorescence after incubation with an NO donor in the presence of the soluble guanylyl cyclase (sGC) activator YC-1 and the phosphodiesterase-inhibitor isobutyl-methyl-xanthine (IBMX). Central nervous system (CNS) cells respond to NO as early as 38% embryogenesis. By using the NADPH-diaphorase technique, we identified somata and neurites of possible NO-synthesizing cells in the CNS. The first NADPH-diaphorase-positive cell bodies appear around 40% embryogenesis in the brain and at 47% in the ventral nerve cord. The number of positive cells reaches the full complement of adult cells at 80%. In the brain, some structures, e.g., the mushroom bodies acquire NADPH-diaphorase staining only postembryonically. Immunolocalization of L-citrulline confirmed the presence of NOS in NADPH-diaphorase-stained neurons and, in addition, indicated enzymatic activity in vivo. In whole mount ventral nerve cords, citrulline immunolabeling was present in varying subsets of NADPH-diaphorase-positive cells, but staining was very variable and often weak. However, in a regeneration paradigm in which one of the two connectives between ganglia had been crushed, strong, reliable staining was observed as early as 60% embryogenesis. Thus, citrulline immunolabeling appears to reflect specific activity of NOS. However, in younger embryos, NOS may not always be constitutively active or may be so at a very low level, below the citrulline antibody detection threshold. For the CNS, histochemical markers for NOS do not provide conclusive evidence for a developmental role of this enzyme.

Neurochemical Architecture of the Central Complex Related to Its Function in the Control of Grasshopper Acoustic Communication

“…In contrast, previous studies on S. gregaria [27] found citrulline-immunoreactive arborizations in all neuropils of the CX and distinguished at least six types of neurons that innervated at least one portion of the CX. In addition, citrulline was also detected in the lower division of another locust species, Locusta migratoria [60]. Though we used the same antibody as Siegl and colleagues and stainings were repeated by different members of our lab with slightly differing protocols, citrulline immunoreactivity was only detected in pontine neurons and probably also in some tangential neurons but was always absent from the CBL.…”

Regeneration of olfactory afferent axons in the locust brain

“…In the locust, identified axons have been shown to regenerate both in the postembryonic (Pätschke et al,2004) and in the late embryonic (Stern and Bicker,2008) ventral nerve cord. In this system, axonal regeneration is at least in part regulated by nitric oxide (Stern and Bicker,2008), which is released by nitrergic axons upon their damage (Stern et al,2010).…”

Development of histamine‐immunoreactivity in the Central nervous system of the two locust species Schistocerca gregaria and Locusta migratoria

“…The Tetraconata (Pancrustacea) concept holds that Insecta are a sister clade of Crustacea (Jenner,2010; Koenemann et al,2010). Insects and crustaceans share common features in neurogenesis with neuroblasts arising in the ventral neuroectoderm giving rise to ganglion mother cells through asymmetrical cell divisions (Dohle et al,2003; Stollewerk and Chipman,2006; Stollewerk and Simpson,2005; Whitington,2003). The expression of molecular markers provided evidence for homologous structures during early nervous system development (Duman‐Scheel and Patel,1999).…”