Neurohormone D induces ionic current changes in cockroach central neurones

Wicher, Dieter; Walther, Christoph; Penzlin, Heinz

doi:10.1007/bf00191716

Cited by 40 publications

(39 citation statements)

References 37 publications

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“…Cell Isolation-Isolation of adult DUM neuron cell bodies was performed under sterile conditions using enzymatic digestion and mechanical dissociation of the median parts of both fifth and terminal abdominal ganglia of adult male cockroaches (Periplaneta americana), as described previously (8,11). Briefly, ganglia were excised, desheathed, and incubated for 10 min at room temperature in bath solution (BS1) containing (in mM): 190 NaCl, 5 KCl, 5 CaCl 2 , 2 MgCl 2 , 10 HEPES, pH 7.4) containing 0.5 mg/ml trypsin (type II, Sigma) and 0.5 mg/ml collagenase (type I, Sigma).…”

Section: Methodsmentioning

confidence: 99%

“…The latter can be blocked by cadmium (8), NPPB, and mefenamic acid (9). This current seems to be physiologically important for: 1) adjusting the free intracellular calcium concentration ([Ca 2ϩ ] i ) (9), and 2) filling intracellular calcium stores (10).…”

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confidence: 99%

“…This current seems to be physiologically important for: 1) adjusting the free intracellular calcium concentration ([Ca 2ϩ ] i ) (9), and 2) filling intracellular calcium stores (10). It is particularly modulated by the adipokinetic hormone neurohormone D (NHD; pQVNF-SPNWNH 2 ) known to accelerate spiking by enhancing calcium influx via the activation of this calcium background current (8,9). In the present study, we further demonstrate that calcium entry via this background current is linked to a NCCE mechanism.…”

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confidence: 99%

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A New Regulation of Non-capacitative Calcium Entry in Insect Pacemaker Neurosecretory Neurons

Wicher

Messutat

Lavialle

et al. 2004

Journal of Biological Chemistry

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Efferent dorsal unpaired median neurons are pacemaker neurosecretory cells. A Ca2؉ background current contributing to the pacemaker activity of cockroach dorsal unpaired median neurons is up-regulated by neurohormone D (NHD), an octapeptide belonging to the adipokinetic hormone family. This modulation accelerates spiking and increases [Ca 2؉ ] i . Using patch clamp, calcium imaging, and immunocytochemistry, we investigated the signaling pathway of NHD-induced current modulation. The membrane depolarization produced by NHD was related to the increase in membrane conductance for Ca 2؉ , Ba 2؉ , or Sr 2؉ . This increase was abolished by LOE 908, an inhibitor of noncapacitive Ca 2؉ entry (NCCE), and it was strongly attenuated by the phospholipase C inhibitor U37122 and the diacylglycerol lipase inhibitor RHC80267. Arachidonic acid and ETYA mimicked the NHD effect on background current. This was abolished by L-NAME and ODQ, inhibitors of NO synthase and NO-sensitive guanylyl cyclase, respectively, but mimicked by the NO donor sodium nitroprusside and 8-bromo-cGMP. Immunocytochemistry using cGMP antibodies indicated that NHD and ETYA increase cGMP. Inhibition of protein kinase G with KT5823 and R p -8-pCPTcGMPS had no effect, whereas zaprinast, a cGMP-specific phosphodiesterase 5,6,9 inhibitor, mimicked the NHD effect. Furthermore, inhibition of the cGMP-activated phosphodiesterase 2 by EHNA and trequinsin abolished the effect of NHD. We conclude that the final step of the NHD signal transduction is the phosphodiesterase 2-induced down-regulation of the cAMP level. This removes a depression of NCCE directly attributed to cAMP because inhibition of protein kinase A with KT5720, R p -cAMPS, and PKI14-22 amide did not mimic the NHD effect. We also demonstrate that any mechanism increasing the cGMP level can induce NCCE.Calcium is a universal intracellular messenger that controls a variety of cellular activities such as secretion, metabolism, or gene expression. Many neuropeptides and hormones affect the free intracellular calcium concentration ([Ca 2ϩ ] i ) 1 by changing calcium fluxes through the plasma membrane and/or by triggering Ca 2ϩ release from intracellular stores. In neurons, calcium influx is mainly accomplished by voltage-gated calcium channels or by receptor-operated calcium channels, e.g. N-methyl-D-asparatic acid receptors (1). In addition, calcium release from intracellular stores can be either induced, for example, by mobilizing inositol 1,4,5-trisphosphate (IP 3 ) or by enhancing calcium influx through voltage-gated or receptoroperated calcium channels (i.e. calcium-induced calcium release). Furthermore, depletion of intracellular calcium stores can activate a capacitative calcium entry (CCE) through storeoperated calcium channels that serve as the main calcium entry route in various non-excitable cells. This capacitative pathway is not the only pathway through which calcium can enter into the cells in response to receptor activation. Many cells can also express additional pathways such as non-capac...

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Section: Methodsmentioning

confidence: 99%

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confidence: 99%

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confidence: 99%

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A New Regulation of Non-capacitative Calcium Entry in Insect Pacemaker Neurosecretory Neurons

Wicher

Messutat

Lavialle

et al. 2004

Journal of Biological Chemistry

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“…While the lower dose of applied AKHs had stimulatory effects on walking activity of macropterous females of P. apterus, higher doses of these hormones showed no or even slightly inhibitory effects on the locomotion of this bug, despite their positive effects on the mobilization of lipids. The presumption that AKH might play an important role as a neuromodulator is supported by findings that CC extracts, neurohormone D, and AKH can exhibit, in a manner similar to octopamine, a strong modulatory effect on the CNS of some insects (Milburn & Roeder, 1962;Milde et al, 1995;Wicher et al, 1994). In addition, the presence of AKH in CNS neurones (Schooneveld et al, 1985) or even in axons was demonstrated by immunohistochemistry, but, as mentioned earlier, a direct explanation of its physiological role is not yet available.…”

Section: Adipokinetic Activity Of Peram-cah-ii and Panbo-rcph In P Amentioning

confidence: 66%

Crustacean red pigment-concentrating hormone Panbo-RPCH affects lipid mobilization and walking activity in a flightless bug Pyrrhocoris apterus (Heteroptera) similarly to its own AKH-peptides

Socha¹,

Kodrı́k²,

Zemek³

2007

Eur. J. Entomol.

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Abstract.In the present study we tested whether the walking activity of macropterous females of the flightless wing-polymorphic bug Pyrrhocoris apterus (L.) can be stimulated by its native adipokinetic hormone Peram-CAH-II and the crustacean red pigmentconcentrating hormone (Panbo-RPCH), and the effectiveness of the latter hormone in a lipid mobilization assay. Two different doses (10 or 40 pmol) of Peram-CAH-II or Panbo-RCPH were injected into 10-day-old macropterous females of P. apterus to evaluate their effects on the walking activity of treated females. The results obtained showed a significant stimulation of walking activity only with the lower dose (10 pmol) of either hormone Peram-CAH-II or Panbo-RPCH. On the contrary, the walking activity of the sameaged females of macropterous morph treated with the higher dose (40 pmol) of these hormones was decreased. The energy substrates mobilized in Panbo-RPCH-treated macropterous females were lipids. The question of whether the stimulation of locomotion by Panbo-RPCH is limited only to P. apterus or if it might also represent an important function of this hormone in other insects or even in crustaceans is discussed.

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“…Previous investigations on identified insect neurosecretory neurons, namely efferent dorsal unpaired median (DUM) neurons in the cockroach Periplaneta americana, have shown that a voltage-independent Ca 2ϩ background current providing for non-capacitative Ca 2ϩ entry (NCCE) changes the spike frequency of these cells. For example, up-regulation of this current by the Periplaneta adipokinetic hormone AKH I (pAKH I: pQ-V-N-F-S-P-N-W⅐NH 2 , also named neurohormone D (6)), accelerates spiking (7,8). A detailed analysis of the signal transduction mechanism, by which AKH I binding to the receptor leads to potentiation of Ca 2ϩ background current, revealed a complex pattern of events including activation of PLC but no apparent contribution from intracellular Ca 2ϩ stores (8).…”

mentioning

confidence: 99%

TRPγ Channels Are Inhibited by cAMP and Contribute to Pacemaking in Neurosecretory Insect Neurons

Wicher

Agricola

Schönherr

et al. 2006

Journal of Biological Chemistry

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From a neuronal cDNA library of the cockroach Periplaneta americana we isolated a 3585-bp cDNA sequence encoding Periplaneta transient receptor potential ␥ (pTRP␥), a protein of 1194 amino acids showing 65% identity to the orthologous Drosophila channel protein dTRP␥. Heterologous expression of pTRP␥ in HEK293 cells produced a constitutively active, non-selective cation channel with a Ca 2؉ :Na ؉ permeability ratio of 2. In contrast to dTRP␥-mediated currents, pTRP␥ currents were partially inhibited by 8-bromo-cAMP, and this effect was not mediated by protein kinase A (PKA) activation. pTRP␥b, a truncated pTRP␥ splice variant missing most of the C terminus, was insensitive to 8-bromocAMP. Thus, the critical cAMP-binding site seems to be located in the C-terminal part of pTRP␥, although there is no common cAMPbinding consensus sequence. While dTRP␥ is only expressed in the photoreceptors, pTRP␥ is expressed throughout the nervous system. In particular it is expressed in dorsal unpaired median (DUM) neurons. In these octopamine-releasing, neurosecretory cells a Ca 2؉ background current contributing to pacemaker activity was found to be up-regulated by the reduction of cAMP level. In addition, the Ca 2؉ background current was inhibited by LOE-908, 2-APB, and La 3؉ , which similarly affected the pTRP␥ current. We thus propose that the pTRP␥ protein is involved in forming the channel passing the Ca 2؉ pakemaking background current in DUM neurons.Proteins of the TRP 2 (transient receptor potential) family form cation-selective and Ca 2ϩ -permeable ion channels with multiple functions (1). The first TRP channel was described in Drosophila photoreceptors where mutants lacking this channel showed a transient receptor potential upon continuous light stimulation (2). In the fly photoreceptors two further TRP proteins, TRPL and TRP␥ (3), contribute to visual transduction (4). TRP proteins have six transmembrane segments, and most of them probably assemble to homo-or heterotetramers to form ion channels.The superfamily of TRP channels has been grouped into several subfamilies (1, 5). Members of the mammalian TRPC (canonical TRP) family show the highest homology with the Drosophila TRP/TRPL/TRP␥ variants. These channels appear to be receptor-operated in that they are activated by a variety of stimuli that lead to activation of phospholipase C (PLC).The modulation of pacemaker conductances is a basic principle to adjust the neuronal activity to the physiological requirements. Certain peptide hormones affect ion channels involved in the regulation of pacemaking. Previous investigations on identified insect neurosecretory neurons, namely efferent dorsal unpaired median (DUM) neurons in the cockroach Periplaneta americana, have shown that a voltage-independent Ca 2ϩ background current providing for non-capacitative Ca 2ϩ entry (NCCE) changes the spike frequency of these cells. For example, up-regulation of this current by the Periplaneta adipokinetic hormone AKH I (pAKH I: pQ-V-N-F-S-P-N-W⅐NH 2 , also named neurohormone D (6)), a...

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Neurohormone D induces ionic current changes in cockroach central neurones

Cited by 40 publications

References 37 publications

A New Regulation of Non-capacitative Calcium Entry in Insect Pacemaker Neurosecretory Neurons

A New Regulation of Non-capacitative Calcium Entry in Insect Pacemaker Neurosecretory Neurons

Crustacean red pigment-concentrating hormone Panbo-RPCH affects lipid mobilization and walking activity in a flightless bug Pyrrhocoris apterus (Heteroptera) similarly to its own AKH-peptides

TRPγ Channels Are Inhibited by cAMP and Contribute to Pacemaking in Neurosecretory Insect Neurons

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