Cholinergic calcium responses in cultured antennal lobe neurons of the migratory locust

Bergmann, Gregor A.; Bicker, Gerd

doi:10.1038/s41598-021-89374-2

Cited by 3 publications

(2 citation statements)

References 61 publications

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“…Investigations on the distantly related, hemimetabolous locust could complement studies on holometabolous species and promote understanding of the general principles of insect immunity. The large size of locust hemocytes, and the recent discovery of a calcium sensor for locust cells [ 111 ] will enable us to study the role of calcium signaling in linking the immune stimulus to NO synthesis as a response. A further advantage of the locust is the large hemolymph volume and, thus, the large number of hemocytes that they share with other basal pterygotes.…”

Section: Discussionmentioning

confidence: 99%

NO Synthesis in Immune-Challenged Locust Hemocytes and Potential Signaling to the CNS

Bergmann¹,

Gerhards²,

Schmitz³

et al. 2021

Insects

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Similar to vertebrates, insects are exposed to a broad variety of pathogens. The innate insect immune system provides several response mechanisms such as phagocytosis, melanization, and the synthesis of antimicrobial or cytotoxic compounds. The cytotoxic nitric oxide (NO), which is also a neurotransmitter, is involved in the response to bacterial infections in various insects but has rarely been shown to be actually produced in hemocytes. We quantified the NO production in hemocytes of Locusta migratoria challenged with diverse immune stimuli by immunolabeling the by-product of NO synthesis, citrulline. Whereas in untreated adult locusts less than 5% of circulating hemocytes were citrulline-positive, the proportion rose to over 40% after 24 hours post injection of heat-inactivated bacteria. Hemocytes surrounded and melanized bacteria in locust nymphs by forming capsules. Such sessile hemocytes also produced NO. As in other insect species, activated hemocytes were found dorsally, close to the heart. In addition, we frequently observed citrulline-positive hemocytes and capsules near the ventral nerve cord. Neurites in the CNS of sterile locust embryos responded with elevation of the second messenger cGMP after contact with purified adult NO-producing hemocytes as revealed by immunofluorescence. We suggest that hemocytes can mediate a response in the CNS of an infected animal via the NO/cGMP signaling pathway.

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Section: Discussionmentioning

confidence: 99%

NO Synthesis in Immune-Challenged Locust Hemocytes and Potential Signaling to the CNS

Bergmann¹,

Gerhards²,

Schmitz³

et al. 2021

Insects

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“…However, the injection of calcium indicators for tracking the flow of calcium into a single pioneer neuron requires a time-consuming preparation of the embryo as a limb fillet [83]. Recently, we found that the next-generation calcium indicator dye Cal-520 AM could be bulk-loaded into locust neurons [95]. This technique has the potential for application to the intact embryo to visualize calcium signals in the pioneers.…”

Section: Limitations and Avenues For Future Improvementsmentioning

confidence: 99%

Looking at Developmental Neurotoxicity Testing from the Perspective of an Invertebrate Embryo

Bicker¹

2022

IJMS

Self Cite

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Developmental neurotoxicity (DNT) of chemical compounds disrupts the formation of a normal brain. There is impressive progress in the development of alternative testing methods for DNT potential in chemicals, some of which also incorporate invertebrate animals. This review briefly touches upon studies on the genetically tractable model organisms of Caenorhabditis elegans and Drosophila melanogaster about the action of specific developmental neurotoxicants. The formation of a functional nervous system requires precisely timed axonal pathfinding to the correct cellular targets. To address this complex key event, our lab developed an alternative assay using a serum-free culture of intact locust embryos. The first neural pathways in the leg of embryonic locusts are established by a pair of afferent pioneer neurons which use guidance cues from membrane-bound and diffusible semaphorin proteins. In a systematic approach according to recommendations for alternative testing, the embryo assay quantifies defects in pioneer navigation after exposure to a panel of recognized test compounds for DNT. The outcome indicates a high predictability for test-compound classification. Since the pyramidal neurons of the mammalian cortex also use a semaphorin gradient for neurite guidance, the assay is based on evolutionary conserved cellular mechanisms, supporting its relevance for cortical development.

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Modulation of Ca2+ oscillation following ischemia and nicotinic acetylcholine receptors in primary cortical neurons by high-throughput analysis

Sasaki,

Hisada,

Kanki

et al. 2024

Sci Rep

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Calcium oscillations in primary neuronal cultures and iPSCs have been employed to investigate arrhythmogenicity and epileptogenicity in drug development. Previous studies have demonstrated that Ca 2+ influx via NMDA and nicotinic acetylcholine receptors (nAChRs) modulates Ca 2+ oscillations. Nevertheless, there has been no comprehensive investigation into the impact of ischemia or nAChR-positive allosteric modulators (PAM) drugs on Ca 2+ oscillations at a level that would facilitate high-throughput screening. We investigated the effects of ischemia and nAChR subtypes or nAChR PAM agonists on Ca 2+ oscillations in high-density 2D and 3D-sphere primary neuronal cultures using 384-well plates with FDSS-7000. Ischemia for 1 and 2 h resulted in an increase in the frequency of Ca 2+ oscillations and a decrease in their amplitude in a time-dependent manner. The NMDA and AMPA receptor inhibition significantly suppressed Ca 2+ oscillation. Inhibition of NR2A or NR2B had the opposite effect on Ca oscillations. The potentiation of ischemia-induced Ca 2+ oscillations was significantly inhibited by the NMDA receptor antagonist, MK-801, and the frequency of these oscillations was suppressed by the NR2B inhibitor, Ro-256981. In the 3D-neurosphere, the application of an α7nAChR agonist increased the frequency of Ca 2+ oscillations, whereas the activation of α4β2 had no effect. The combination of nicotine and PNU-120596 (type II PAM) affected the frequency and amplitude of Ca 2+ oscillations in a manner distinct from that of type I PAM. These systems may be useful not only for detecting epileptogenicity but also in the search for neuroprotective agents against cerebral ischemia. Supplementary Information The online version contains supplementary material available at 10.1038/s41598-024-77882-w.

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Cholinergic calcium responses in cultured antennal lobe neurons of the migratory locust

Cited by 3 publications

References 61 publications

NO Synthesis in Immune-Challenged Locust Hemocytes and Potential Signaling to the CNS

NO Synthesis in Immune-Challenged Locust Hemocytes and Potential Signaling to the CNS

Looking at Developmental Neurotoxicity Testing from the Perspective of an Invertebrate Embryo

Modulation of Ca2+ oscillation following ischemia and nicotinic acetylcholine receptors in primary cortical neurons by high-throughput analysis

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