Neuropeptide induction of cyclic GMP increases in the insect CNS: resolution at the level of single identifiable neurons

Ewer, John; Vente, Jan de; Truman, JW

doi:10.1523/jneurosci.14-12-07704.1994

Cited by 93 publications

(90 citation statements)

References 32 publications

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“…With respect to the first possibility, and as noted above, EH may play a role in activating this circuit prior to eclosion. This would be consistent with the action of EH on bursicon-expressing neurons in Manduca at larval ecdysis (Ewer et al, 1994), and also with the fact that flies in which the EH-expressing neurons have been ablated largely fail to expand their wings (McNabb et al, 1997). With respect to the second possibility, it may be that the wing expansion circuit is armed or activated strictly after eclosion, but that the danger of its accidental activation prior to eclosion exists and must be avoided.…”

Section: Discussionsupporting

confidence: 53%

Eclosion gates progression of the adult ecdysis sequence ofDrosophila

Peabody

White

2013

Journal of Experimental Biology

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SUMMARYAnimal behavior is often organized into stereotyped sequences that promote the goals of reproduction, development and survival. However, for most behaviors, the neural mechanisms that govern the order of execution of the motor programs within a sequence are poorly understood. An important model in understanding the hormonal determinants of behavioral sequencing is the ecdysis sequence, which is performed by insects at each developmental transition, or molt. The adult ecdysis sequence in Drosophila includes the emergence of the insect from the pupal case followed by expansion and hardening of the wings. Wing expansion is governed by the hormone bursicon, and stimulation of the bursicon-expressing neurons in newly eclosed flies induces rapid wing expansion. Here we show that that such stimulation delivered prior to eclosion has no immediate effect, but does cause rapid wing expansion after eclosion if the stimulus is delivered within 40 min of that event. We observe a similar delayed effect upon stimulation of a single pair of bursicon-expressing neurons previously identified as command neurons for wing expansion. We conclude that command neuron stimulation enables the motor output pathway for wing expansion, but that this pathway is blocked prior to eclosion. By manipulating the time of eclosion, we demonstrate that some physiological process tightly coupled to adult ecdysis releases the block on wing expansion. Eclosion thus serves as a behavioral checkpoint and complements hormonal mechanisms to ensure that wing expansion strictly follows eclosion in the ecdysis sequence.

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Section: Discussionsupporting

confidence: 53%

Eclosion gates progression of the adult ecdysis sequence ofDrosophila

Peabody

White

2013

Journal of Experimental Biology

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“…EH release normally takes place well in advance of ecdysis. In Manduca, the delay period is about 20-25 min for larval ecdysis (Ewer et al, 1994), and 2-3 h for adult eclosion (Ewer and Truman, 1996). Decapitation of Manduca pharate adults during the delay period leads to the rapid onset of eclosion behavior (Ewer et al, 1997;Reynolds, 1980), suggesting that the delay is due to descending inhibition from the head.…”

Section: The Role Of the Eh Neurons In The Lon Responsementioning

confidence: 99%

“…Based on the results of head ligations described above, it must reside in the head. In Manduca, neurons of the cell 27/704 group are EH targets (Ewer et al, 1994;Ewer et al, 1997) and some that are located in the subesophagheal ganglion are candidate sources of the inhibition (Fuse and Truman, 2002;Zitnan and Adams, 2000). The identity of the Drosophila inhibitory neurons is less clear.…”

Section: Photoreceptors and The Lon Responsementioning

confidence: 99%

Light and peptidergic eclosion hormone neurons stimulate a rapid eclosion response that masks circadian emergence inDrosophila

McNabb

Truman

2008

Journal of Experimental Biology

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SUMMARYLight signals can entrain circadian clocks, but they can also mask aspects of the circadian output. We have analyzed the masking effects of a lights-on (LOn) signal on Drosophila eclosion. The LOn response results in 12-21% of the flies that emerge on a given day eclosing within 10 min of the LOn signal. Flies that lack the neuropeptide eclosion hormone (EH), or in which its release is inhibited by the tetanus toxin light chain, lack the response. Optic photoreceptors in both the ocelli and the compound eyes appear to be required for the response. The LOn signal has two effects: (1) it drastically reduces the interval between EH release and eclosion, presumably by suppressing a transient descending inhibition that immediately follows EH release, and (2) it stimulates premature EH release. The LOn signal does not influence the latency of wing spreading, an EH-regulated post-ecdysis behavior.

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“…Central release of EH is associated with cGMP production in a specific network of neurons 27/704 and L 2,5 (Ewer et al, 1994(Ewer et al, , 1997aFuse et al, 2002) and these neurons show cGMP elevation in response to ETH and EH treatment in vitro (Gammie and Truman, 1999;Žitňan and Adams, 2000). The presence of ETHR-A in the VM cells (Kim et al, 2006a) clearly suggests that ETH is acting through EH to elicit cGMP production and excitability of 27/704 neurons.…”

Section: Roles Of Central Neuropeptides and Eth Receptors In Ecdysismentioning

confidence: 99%

“…The presence of ETHR-A in the VM cells (Kim et al, 2006a) clearly suggests that ETH is acting through EH to elicit cGMP production and excitability of 27/704 neurons. However, initial cGMP elevation in Manduca SG and TG1-3 occurs prior to EH release (Ewer et al, 1994;Žitňan and Adams, 2000), and isolated abdomens of Bombyx larvae show normal cGMP elevation in 27/704 homologs without apparent EH release (Žitňan et al, 2002). These data indicate that cGMP elevation in the CNS requires some additional factors.…”

Section: Roles Of Central Neuropeptides and Eth Receptors In Ecdysismentioning

confidence: 99%

Complex steroid–peptide–receptor cascade controls insect ecdysis

Žitňan

Kim

Žitňanová

et al. 2007

General and Comparative Endocrinology

155

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SUMMARYInsect ecdysis sequence is composed of pre-ecdysis, ecdysis and post-ecdysis behaviors controlled by a complex cascade of peptide hormones from endocrine Inka cells and neuropeptides in the central nervous system (CNS). Inka cells produce pre-ecdysis and ecdysis triggering hormones (ETH) which activate the ecdysis sequence through receptor-mediated actions on specific neurons in the CNS. Multiple experimental approaches have been used to determine mechanisms of ETH expression and release from Inka cells and its action on the CNS of moths and flies. During the preparatory phase 1-2 days prior to ecdysis, high ecdysteroid levels induce expression of ETH receptors in the CNS and increased ETH production in Inka cells, which coincides with expression of nuclear ecdysone receptor (EcR) and transcription factor cryptocephal (CRC). However, high ecdysteroid levels prevent ETH release from Inka cells. Acquisition of Inka cell competence to release ETH requires decline of ecdysteroid levels and β-FTZ-F1 expression few hours prior to ecdysis. The behavioral phase is initiated by ETH secretion into the hemolymph, which is controlled by two brain neuropeptides -corazonin and eclosion hormone (EH). Corazonin acts on its receptor in Inka cells to elicit low level ETH secretion and initiation of pre-ecdysis, while EH induces cGMP-mediated ETH depletion and consequent activation of ecdysis. The activation of both behaviors is accomplished by ETH action on central neurons expressing ETH receptors A and B (ETHR-A and B). These neurons produce numerous excitatory or inhibitory neuropeptides which initiate or terminate different phases of the ecdysis sequence. Our data indicate that insect ecdysis is a very complex process characterized by two principal steps: 1) Ecdysteroid-induced expression of receptors and transcription factors in the CNS and Inka cells. 2) Release and interaction of Inka cell peptide hormones and multiple central neuropeptides to control consecutive phases of the ecdysis sequence.

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Neuropeptide induction of cyclic GMP increases in the insect CNS: resolution at the level of single identifiable neurons

Cited by 93 publications

References 32 publications

Eclosion gates progression of the adult ecdysis sequence ofDrosophila

Eclosion gates progression of the adult ecdysis sequence ofDrosophila

Light and peptidergic eclosion hormone neurons stimulate a rapid eclosion response that masks circadian emergence inDrosophila

Complex steroid–peptide–receptor cascade controls insect ecdysis

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