Cyclic AMP does not mediate the action of synthetic hypertrehalosemic peptides from the corpus cardiacum of Periplaneta americana

Orr, Gregory L.; Gole, J.W.D.; Jahagirdar, A.P.; Downer, Roger; Steele, J.E.

doi:10.1016/0020-1790(85)90098-8

Cited by 43 publications

(8 citation statements)

References 24 publications

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“…Figs 1 and 3 demonstrate also that the hypertrehalosemic hormones, HT-I and HT-II, elevate intracellular concentrations of calcium and, therefore, confirm previous suggestions [9,12] that these peptides bind to a receptor to induce increased levels of cytosolic calcium. Vertebrate glucagon is now believed to possess two distinct receptors, one of which is coupled to inositol phospholipid breakdown and calcium gating and the other to the adenylate cyclase complex [14].…”

Section: Resultssupporting

confidence: 85%

“…The hypertrehalosemic peptides (HT-I and HT-II) are functionally similar to vertebrate glucagon in that they activate glycogen phosphorylase in insect fat body to cause marked elevation of trehalose, the major haemolymph sugar of insects [9]. However, the insect peptides, unlike glucagon, do not mediate their effects through production of cyclic AMP and, instead, may induce increased intracellular concentrations of calcium.…”

Section: Introductionmentioning

confidence: 99%

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Calcium involvement in mediating the action of octopamine and hypertrehalosemic peptides on insect haemocytes

et al. 1987

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Octopamine, the hypertrehalosemic peptides HT-I and HT-II and the calcium ionophore A23187 elevate intracellular calcium levels in cultured haemocytes of Malaeosoma disstria (Lepidoptera: Lasiocampidae). The octopamine-mediated response is dose-dependent and the magnitude of the response is influenced by the concentration of calcium in the incubation medium. Mianserin, an inhibitor of octopamine-mediated elevation of cyclic AMP production, blocks the octopamine-mediated increase in intracellular calcium but has no effect on the HT-I-and HT-II-mediated responses. The results indicate that some effects of octopamine are mediated through agonist-dependent calcium gating whereas others are expressed through receptors coupled to adenylate cyclase. The study also confirms previous suggestions that HT-I and HT-II elevate intracellular calcium concentrations.

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Section: Resultssupporting

confidence: 85%

Section: Introductionmentioning

confidence: 99%

Calcium involvement in mediating the action of octopamine and hypertrehalosemic peptides on insect haemocytes

et al. 1987

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“…Firstly, phosphorylase activities were increased by the injection of Munduca AKH and secondly through chilling. The action of AKH involves intracellular second messengers [8,9], while chilling has a direct effect on phosphorylase phosphatase but not on the kinase [lo]. In the present communication, changes of phosphorylase activities after activation through AKH and chilling have been analyzed under various conditions in vivo and in vitro to gain insight into the fine-tuning of enzyme activity in larval fat body of M. sextu.…”

Section: Introductionmentioning

confidence: 98%

Regulation of fat body glycogen phosphorylase in larval tobacco hornworm, Manduca sexta

Siegert

1992

Arch Insect Biochem Physiol

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Activation and inactivation of fat body glycogen phosphorylase was investigated in ligated abdomens of IarvalManduca sexta and in vitro. After maximal activation through Manduca adipokinetic hormone (AKH) or chilling, inactivation of glycogen phosphorylase commenced as soon as the stimulus for the activation was removed indicating that the enzyme system in the fat body is fine-tuned to low phosphorylase activities which is necessary to allow glycogen synthesis. In intact ligated abdomens phosphorylase can be activated repeatedly by either stimulus showing that the fat body system does not lose its responsiveness. It was impossible to achieve complete conversion of the inactive form of phosphorylase into the active form even after administration of AKH and simultaneous chilling.

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“…Subsequently it was shown to be an octapeptide of the amino acid sequence pGlu-Val-Asn-PheSer-Pro-Asn-TrpNH2 (Scarborough et al 1984;Baumann and Penzlin 1984;Witten et al 1984). Neurohormone D is also termed myotropin I , periplanetin CC I (Scarborough et al 1984), hypertrehalosemic hormone HT I (Orr et al 1985;Jahagirdar et al 1987) and Pea-CAH-I (Raina and G/ide 1988).…”

Section: Introductionmentioning

confidence: 99%

Neurohormone D induces ionic current changes in cockroach central neurones

1994

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The octapeptide neurohormone D (NHD), a member of the family of adipokinetic hormones (AKH-peptides), increases the frequency of spontaneous activity in dorsal unpaired median (DUM) neurones isolated from the terminal ganglion of the cockroach Periplaneta americana. The increase in spike frequency is accompanied by changes in the shape and the amplitude of the single action potentials, e.g. a more pronounced afterhyperpolarization. Effects of NHD on membrane currents were investigated in these DUM cells with whole-cell voltage-clamp measurements. A voltage-independent Ca2+ current flowing at the resting potential (ICa,R) was found. NHD, at nanomolar concentrations, enhanced this ICa,R in a concentration-dependent manner. 0.1 mM Cd2+ markedly reduced ICa,R and in this case ICa,R was hardly potentiated by NHD. In the presence of NHD a fast activating Ca(2+)-dependent K+ current sensitive to charybdotoxin and to low concentrations of tetraethylammonium was augmented. The enhanced afterhyperpolarization of action potentials can be accounted for by the increase in the Ca(2+)-dependent K+ current. The changes of the membrane currents induced by NHD are discussed with respect to further effects on the spike pattern and in relation to the previously described mode of action of AKH-peptides in other preparations.

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Cyclic AMP does not mediate the action of synthetic hypertrehalosemic peptides from the corpus cardiacum of Periplaneta americana

Cited by 43 publications

References 24 publications

Calcium involvement in mediating the action of octopamine and hypertrehalosemic peptides on insect haemocytes

Calcium involvement in mediating the action of octopamine and hypertrehalosemic peptides on insect haemocytes

Regulation of fat body glycogen phosphorylase in larval tobacco hornworm, Manduca sexta

Neurohormone D induces ionic current changes in cockroach central neurones

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