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PubMedDate not supplied

The metabolic neuropeptides of the corpus cardiacum from the potato beetle and the American cockroach are identical.

Two neuropeptides with adipokinetic activity in Locusta migratoria and hypertrehalosaemic activity in Periplaneta americana were purified by high performance liquid chromatography from the corpus cardiacum of the Colorado potato beetle, Leptinotarsa decemlineata. The sequences of both peptides, designated Led-CC-I and Led-CC-II, were determined by pulsed-liquid phase sequencing employing Edman degradation after deblocking enzymatically the N-terminal pyroglutamate residue. The C-terminal of both peptides were blocked and neither molecule was cleaved by carboxypeptidase. Both peptides were found to be octapeptides; Led-CC-I has the primary structure pGlu-Val-Asn-Phe-Ser-Pro-Asn-Trp-NH2, and Led-CC-II has the primary sequence pGlu-Leu-Thr-Phe-Thr-Pro-Asn-Trp-NH2. These structures are identical to the two hypertrehalosaemic hormones from the American cockroach. Preliminary experiments show that the synthetic peptides are apparently involved in the control of amino acid metabolism during flight of the potato beetle.

Amino Acid Sequence↗
PubMed1982

Olfactory receptor responses of the nymphal American cockroach to sex pheromones and their mimics.

1. EAG responses to highly purified sex pheromones (periplanone-A and -B), sex pheromone mimics [germacrene-D, (+)-verbanyl acetate and (+)-trans-verbenyl acetate] and general odor (camphor) were recorded from both sexes of adult and three nymphal stages (7, 10 and 11th instars) of the American cockroach. 2. The M/F ratios were evaluated for each stage by stimulation with the above chemicals. 3. The ratio values indicated undeveloped sex pheromone receptor on the antennae of 7th male instar and females of all the stages. On the other hand, precursory development of the receptor was expected on the antennae of males of the old-aged nymphal instars and full development on the adult male antennae.

Animals↗
PubMed1985

Endocrine regulations of ovarian maturation in the cockroach Blaberus discoidalis.

The first gonotrophic cycle of oocyte maturation was defined for virgin Blaberus discoidalis cockroaches. A high correlation was found between growth of the basal oocytes and increased ovarian protein content. Allatectomy blocked ovarian protein formation, whereas JH-III administration compensated for the loss of the corpora allata. Experiments involving neuro-endocrine surgery and hormone replacement therapy indicated that JH, alone, could stimulate ovarian protein formation; however, the addition of neuroendocrine extracts enhanced the JH effects. The data suggest that both JH and neurohormones stimulate aspects of ovarian protein formation in this insect.

Animals↗
PubMed1989

Ionic currents in the soma of an identified cockroach motoneurone recorded under voltage-clamp.

1. Membrane currents have been recorded from the soma of a bifunctional basalar/coxal depressor motoneurone in the metathoracic ganglion of the cockroach (Periplaneta americana) using a two-electrode voltage-clamp technique. 2. This motoneurone cell body is normally inexcitable when studied under current-clamp. Appropriate depolarizing command steps evoke rapid transient outward currents and late outward currents. 3. Late outward currents are dominated by a Ca-dependent component that confers an N-shaped I-V relationship on the neurone. 4. The Ca-dependent outward current is suppressed by Cd2+ (1 mM), Mn2+ (5 mM) or verapamil (50 microM). 5. Externally applied tetraethylammonium ions (TEA+) (25 mM) block the Ca-dependent current, but also appear to suppress a component of the late outward current that is independent of Ca2+. 6. Aminopyridines cause only minor suppression of late outward currents, but shift the peak in the N-shaped I-V relationship to more negative potentials. 7. The reversal potential of tail currents recorded following pre-pulses to +50 mV were dependent upon the pre-pulse duration; increasing the duration from 10 to 50 msec caused a +17 mV shift in tail current reversal potential. 8. A five-fold increase in the K+ concentration of the solution bathing the preparation only produced small and inconsistent changes in the reversal potential of tail currents. 9. Five-fold reduction in external Cl- caused no change. 10. The dependence of tail current reversal potential upon pre-pulse duration and the limited effect of alterations in the composition of the bathing solution are discussed in the context of restricted ion movements near the external surface of the cell membrane.

Aminopyridines↗
PubMed1989

The electroretinogram of the cockroach Leucophaea maderae.

1. We have previously found that two components, the off-transient and the sustained component, of the electroretinogram (ERG) recorded from the eye of the cockroach Leucophaea maderae exhibit circadian rhythms in amplitude (Wills et al., 1985). 2. Analysis of the intensity-response functions of the two rhythmic components reveals that the circadian modulation of this visual system involves at least two independent regulatory processes. 3. Surgical and pharmacological manipulations suggest anatomically distinct sites of origin for the off-transient and the sustained component. 4. The results suggest that in this system the circadian pacemaker regulates visual processing both peripherally, at the level of the photoreceptors, and centrally, at the source of the off-transient.

Animals↗
PubMed1989

Simulation of the activation of fat body glycogen phosphorylase and trehalose synthesis by peptide hormones in the American cockroach.

A model is described which simulates activation of glycogen phosphorylase and induction of trehalose synthesis in the fat body of the American cockroach, Periplaneta americana, by two hypertrehalosaemic peptides. Parameters for the model were estimated from literature data (Siegert et al., Insect Biochem. 16, 365), with the exception of the half-life of the physiologically active peptides, which was estimated from the model. The model describes satisfactorily the activation of glycogen phosphorylase and the increase of haemolymph carbohydrates, which is dependent on the activation of glycogen phosphorylase in the model. It further explains the observed differences in sensitivity for glycogen phosphorylase activation and increase in haemolymph carbohydrates by these peptides. Best fits were obtained with a physiological half-life of about 12-15 min for the peptides. This value is similar to what can be calculated from the in vivo effects of these peptides on heart beat (Gersch et al., Zool. Jb. Physiol. 86, 17), but it is considerably shorter than the published half-life of 1 h for radioactive peptide (Skinner et al., Insect Biochem. 17, 433). However, both values are compatible if part of the peptides in the haemolymph is not present in freely dissolved form, but bound to a haemolymph component. The model half-life would then represent the half-life of the free, physiologically active peptide, which was estimated from the disappearance of radioactive peptide to be about 12-15 min. This suggests, that the model half-life is realistic and physiologically more important than the half-life of radioactive peptide of 1 h.

Animals↗
PubMed1997

Coding properties of peak and average response rates in American cockroach olfactory sensory cells.

The response of phasic neurons is often measured in terms of average spiking rates over arbitrarily selected time intervals. Averages taken over inappropriate intervals may severely reduce the information content of data, as we show here using response data from female American cockroach peripheral olfactory cells. We demonstrate that a 100-ms period around the peak response contains the best information for discriminating among odors at moderate to high concentrations. Further, the 100-ms post-peak response period contains the best information at low concentrations, as well as in situations where it is important to minimize errors in misidentifying the quality of an odor. Averaging the data over the full 0.5 s stimulus period degrades the odor separation qualities of the data.

Action Potentials↗
PubMed1990

Changes in the sensitivity of adult cockroach corpora allata to a brain allatostatin.

There are major changes in the sensitivity of corpora allata from the cockroach Diploptera punctata toward the allatostatic tridecapeptide APSGAQRLYGFGL-amide (ASAL) during the female reproductive cycle, as revealed by measurement of juvenile hormone (JH) biosynthesis in vitro. Glands from recently molted adult females show only 30-40% inhibition at 10 nM ASAL, falling to a minimum of less than 10% on day 5 at the peak of spontaneous JH synthesis in vitro. The decline in JH synthesis observed in post-vitellogenic females is accompanied by a dramatic increase to ca. 90% ASAL sensitivity at 10 nM by day 6. Then sensitivity slowly wanes during subsequent ovulation and pregnancy to the levels typical of previtellogenic and virgin females. Full dose/response studies reveal a second level of response at ca. 1 microM, which resembles the pattern obtained from whole brain extracts. We conclude that physiological sensitivity to ASAL (IC50 ca. 0.1 nM) is correlated with the preparation for choriogenesis, and we suggest that 1000 times higher doses give a cross-reaction with related allatostatic receptor(s) that confer important sensitivity at other development stages.

Amino Acid Sequence↗
PubMed1995

Neural and hormonal regulation of growth of corpora allata in the cockroach, Diploptera punctata.

DNA synthesis and mitosis in the corpora allata (CA) of adult Diploptera punctata males were investigated with total cell count after 5'-bromo-2'-deoxyuridine immunodetection and colchicine arrestment both in vivo and in vitro. The CA exhibited a single wave of DNA synthesis followed by cell division during the first 4 days after the imaginal ecdysis. A second mitotic wave was experimentally induced after the nervous connections between the CA and the brain were severed on day 4. Spontaneous mitosis was abolished in cockroaches treated with a juvenile hormone (JH) analog. This inhibitory regulation in vivo appeared to act through brain neurosecretory cells since in the denervated CA mitotic activity was unaffected by JH treatment. An in vitro system supporting growth of the corpus allatum was established to study direct hormonal effects. By using continuous bromodeoxyuridine labeling in vitro for 6 days, we showed that DNA synthesis of corpus allatum cells was unaffected by direct contact with JH. In contrast, 20-hydroxyecdysone exerted direct mitogenic action on allatal cells. These and previous results suggest that CA cells alternate between JH synthesis and a proliferative state in which they divide in a self-renewing fashion to yield differentiated progeny. We propose that in newly enclosed adult Diploptera punctata males, low JH titer and high ecdysteroid titer promote mitosis in CA cells. As the ecdysteroid titer declines, JH produced by the CA acts on brain neurosecretory cells which dispatch inhibitory signals through nerves to prevent continuous proliferation of CA cells.

Animals↗
PubMed1996

Calcium-dependent action of hypertrehalosemic hormone on activation of glycogen phosphorylase in cockroach fat body.

Signaling mechanisms for Blaberus discoidalis hypertrehalosemic hormone (Bld-HrTH)-dependent glycogen phosphorylase activation were investigated in vitro using fat body of the tropical cockroach, B. discoidalis. Brief treatment of fat bodies with Bld-HrTH in the absence of extracellular Ca2+ showed a significant activation of phosphorylase. Although extracellular Ca2+ was required for a full activation of phosphorylase by Bld-HrTH, stimulation in the absence of extracellular Ca2+ suggested that intracellular Ca2+ was also involved in Bld-HrTH signal transduction. Thapsigargin and thimerosal mobilize Ca2+ from intracellular stores by different mechanisms, and both chemicals stimulated phosphorylase activities as effectively as a maximum dose of Bld-HrTH. Bld-HrTH likely induces intracellular Ca2+ release followed by extracellular Ca2+ entry across the plasma membrane. Inositol-1,4,5-trisphosphate (InsP3) levels were greatly increased by Bld HrTH in a time- and dose-dependent manner, suggesting that InsP3 might be a Ca(2+)-mobilizing intracellular second messenger for Bld-HrTH.

Animals↗
PubMed1996

Target of cockroach allatostatin in the pathway of juvenile hormone biosynthesis.

Allatostatins, peptides with an YXFGL-amide C-terminus, cause a rapid and reversible inhibition of the sesquiterpenoid juvenile hormone III biosynthesis by cockroach corpora allata in vitro. Inhibition is relieved by farnesol and by mevalonate, and neither HMG-CoA reductase nor HMG-CoA synthesis (HMG-CoA synthase and acetoacetyl-CoA lyase) are inhibited by allatostatin. The neuropeptide is more effective as an inhibitor of JH III synthesis in glucose or amino acid-driven glands than in acetate-driven glands. Incorporation of label from acetate into JH III is increased whereas incorporation of label from glucose is decreased by allatostatin. Citrate is a very effective precursor for HMG-CoA synthesis in homogenates of corpora allata. We propose that inhibition of JH III biosynthesis by the tridecapeptide APSGAQRLYGFGL-amide occurs at the first committed step(s) of JH III synthesis, i.e. the transfer of 2C units from mitochondria to the cytoplasm by the tricarboxylate carrier and/or the ATP-citrate lyase.

Acetyl Coenzyme A↗
PubMed1989

The 24-h rhythm of metabolic activity of the cockroach circadian pacemaker.

In the cockroach, Leucophaea maderae, the optic lobes contain a circadian pacemaker. The metabolic activity of optic lobe neuropils was measured at 17 time points over a 24-h period in constant darkness, using cytochrome oxidase activity as functional marker. The results revealed a clear 24-h energy metabolism rhythm in neuropils and particularly in the lobula plate, a part of the region which is assumed to include a circadian pacemaker in this species.

Animals↗
PubMed1989

Molecular target size of an L-glutamate receptor from the cockroach central nervous system.

L-Glutamate binding to cockroach central nervous system (CNS) membranes is unaffected by freeze-drying and subsequent rehydration. The dissociation constant is similarly unaltered by irradiation at a dose of 3 Mrad which affects only the number of biologically active binding sites. A molecular weight estimate for this insect CNS L-glutamate receptor was performed using irradiation inactivation analysis. By this method a molecular target size of approximately 77.8 kDa was determined. This figure is in agreement with the molecular weight found by other authors for L-glutamate binding sites in the rat brain.

Animals↗
PubMed1996

Spatial and temporal analysis of evoked neural activity in optical recordings from American cockroach antennal lobes.

The spatio-temporal patterns of neural activity evoked by electrical stimuli to the antennal nerve (AN) in male cockroach antennal lobes (ALs) in vivo were analyzed by optical imaging using a voltage-sensitive dye. The response pattern was initially a depolarization on the AN and subsequently a depolarization followed by a hyperpolarization on the whole area of macroglomerulus (MG) and a part of ordinary glomerulus (OG). It was suggested by the pharmacological results that the depolarizing responses on the AL consist of both a presynaptic response, representing synchronous compound action potentials from the AN, and a postsynaptic response, representing synchronous compound excitatory postsynaptic potentials and action potentials from neurites of AL neurons, and that the inhibitory responses of GABAergic local interneurons in the AN are different in time course from that in the AL.

Action Potentials↗
PubMed1984

Influence of octopamine on trehalase activity in muscle and hemolymph of the American cockroach, Periplaneta americana L.

Injection of adult male cockroaches (Periplaneta americana) with 10 microliter 1 microM octopamine causes elevated activity of trehalase (alpha, alpha-trehalose glucohydrolase; EC 3.2.1.28) in hemolymph and muscle but not in gut. Tyramine, dopamine and glutamate, at the same concentration, failed to elicit any effect on trehalase activity. Determination of some kinetic parameters for muscle and hemolymph trehalases reveal that octopamine causes an increase in Vmax without any significant alteration in the Km of the enzyme for trehalose. The results are discussed in terms of the physiological significance of octopamine-mediated activation of tissue trehalases.

Animals↗
PubMed1983

Isolation and partial characterization of a second myotropic peptide from the hindgut of the cockroach, Leucophaea maderae.

Proctolin and a second myotropic peptide were extracted from the hindgut of the cockroach Leucophaea maderae with methanol-water-acetic acid (90:9:1). The two peptides were easily separated by HPLC on a mu-Bondapak-phenyl column. Like proctolin, the second peptide was heat stable and was inactivated by the exopeptidases aminopeptidase M and carboxypeptidase Y. The response of the isolated hindgut to the new peptide was distinguishable from the response to proctolin by the following features: (a) a longer interval following application (1-4 min) to reach a maximum contraction, and (b) a much larger amplitude for single phasic contractions. Like proctolin, the new peptide could cause a protracted stimulation of the hindgut for more than 2 hr.

Animals↗
PubMed1984

A comparison of the effect of kainate and some related amino acids on locomotor activity in cockroaches and electrical activity recorded from locust ventral nerve cord.

The ED50 for loss of righting behaviour of cockroaches induced by kainate (43 mumol/kg body weight) indicated the toxicity of kainate to be much greater than would have been predicted from the excitatory action of this amino acid at insect skeletal muscle fibres. N-Methyl-D-aspartate had little effect on righting behaviour (ED50 greater than 3500 mumol/g body weight). Electrical recordings from the locust ventral nerve cord showed kainate (0.1-2 mM) to have a depolarizing action on neurons within the metathoracic ganglion. The depolarizing action of kainate was partially resistant to tetrodotoxin. The kainate-induced abolition of rostrally evoked potentials recorded in the abdominal connectives from the metathoracic ganglion suggests that the giant fibres are sensitive to kainate. Domoic acid was 46 times more potent than kainate. The lack of effect of N-methyl-D-aspartate (2 mM), dihydrokainate (2 mM), quisqualate (2 mM) and L-glutamate (20 mM) on nerve cords in the present experiments suggests that the kainate receptors in this preparation show a chemical selectivity comparable to that observed at vertebrate central neurones.

Animals↗
PubMed1984

Distribution of 5-hydroxytryptamine and indolealkylamine metabolites in the American cockroach, Periplaneta americana L.

A procedure is described for simultaneous estimation of tryptophan (TP), 5-hydroxytryptophan (5-OHTP), 5-hydroxytryptamine (5-HT), 5-hydroxyindoleacetic acid (5-HIAA), N-acetyl 5-hydroxytryptamine (NA5-HT) and N-acetyldopamine (NADA) using high performance liquid chromatography with coulometric electrochemical detection. The procedure has been used to determine the distribution of these compounds in the central nervous system of the American cockroach, Periplaneta americana. The ratio of TP:5-HT is greatest in the cerebral ganglia (6.5) with lesser ratios evident in the thoracic ganglia (15.5-18.9) and abdominal ganglia (9.6-11.2). Relatively low concentrations of 5-OHTP and NA5-HT were observed in the cerebral ganglia whereas 5-HIAA was not detected. Incubation of ganglia resulted in increased concentrations of NA5-HT. Reserpine reduced levels of 5-HT and NADA whereas probenecid caused a marked reduction in TP and slight elevation of NADA levels. No MAO activity was detected in the central nervous system.

5-Hydroxytryptophan↗