Restricted specificity of a hyperglycaemic factor from the corpus cardiacum of the stick insect Carausius morosus

Extracts of the corpora cardiaca of the stick insect Carausius morosus elevate the haemolymph carbohydrate concentration in adult and 6th-instar larvae which are ligated behind the first pair of legs, but not in non-ligated (intact) insects. The increase in haemolymph sugars is due to trehalose elevation, is time dependent (with a maximal effect about 90–120 min after injection), and is dose dependent (needing 0.005 gland equivalents for a significant effect and a tenfold higher dose for a maximal response). The hyperglycaemic factor is localised entirely in the corpora cardiaca and appears to be specific to stick insects; corpora cardiaca extracts of two lepidopteran species (Acherontia atropos and Aglais urticae) and of Locusta migratoria have no effect, whereas corpora cardiaca extracts of the stick insects Cuniculina impigra and Sipyloidea sipylus have similar activity to those from C. morosus. This specificity is also shown when S. sipylus is used as the recipient. Synthetic adipokinetic hormone and red pigment concentrating hormone possess no hyperglycaemic activity in the stick-insect system. Two peaks of hyperglycaemic activity were obtained after column chromatography of corpora cardiaca extract of C. morosus on Sephadex G-25 and Sephadex LH-20. The factor seems to act via activation of fat-body glycogen phosphorylase, which, although 60% active in the control insects, is significantly increased to approx. 85% upon corpora cardiaca injection. However, the activation is demonstrated in ligated and intact insects. No significant decrease in the glycogen level of the fat body is observed after corpora cardiaca injection.     

A comparative study on the isolation of adipokinetic and hypertrehalosaemic factors from insect corpora cardiaca

ABSTRACT. Extracts of corpora cardiaca from two cockroaches, Nauphoeta cinerea Olivier and Leucophaea maderae F., from a cricket, Gryllus bimaculatus De Geer, from the Colorado potato beetle, Leptinotarsa decemlineata Say, and from the sphinx moth, Sphinx ligustri L. were assayed for adipokinetic and hypertrehalosaemic activity, in acceptor locusts ( Locusta migratoria L.) and cockroaches ( Periplaneta americana L.) respectively. Both bioassays give positive results with all corpus cardiacum material tested except that from the sphinx moth; in this insect haemolymph lipid concentrations (but not those of the total carbohydrate) are, however, increased after injection of an extract of corpora cardiaca from the same species. A similar result is obtained when specimens of G. bimaculatus are injected with an extract of corpora cardiaca from G. bimaculatus. Biological activities of corpus cardiacum extracts from all species investigated can be resolved on reversed-phase high-performance liquid chromatography. Gland extracts from the two cockroach species each show a single absorbance peak which has hypertrehalosaemic activity, but with a (common) retention time distinct from all previously described arthropod neuropeptides. The corpora cardiaca of G. bimaculatus contain also a novel adipokinetic factor with a retention time distinct from previously characterized arthropod hormones, as well as from the new cockroach factor described in this study. The two hypertrehalosaemic factors from the corpora cardiaca of the potato beetle coelute with the hypertrehalosaemic hormones I and II of the American cockroach. The active (adipokinetic) compound from glands of S. ligustri appears to coelute with locust adipokinetic hormone I.     

Adipokinetic hormone content of the corpora cardiaca in gregarious and solitary migratory locusts

Abstract. The adipokinetic hormone (AKH-I and AKH-II) content of the corpora cardiaca from adult males of crowded (gregarious) and isolated (solitary) Locusta migratoria migratorioides (Reiche & Fairmaire) was quantified by reverse-phase high-performance liquid chromatography.Significantly less total hormone was found in the corpora cardiaca of crowded locusts than in those glands of isolated locusts at the age of 12–19 days after fledging.The ratio of AKH-I/AKH-II was higher in crowded than in isolated locusts at this age.From the age of 12–19 days to that of 25–30 days, AKH content increased significantly in the corpora cardiaca of crowded locusts, but no such increase was found in the glands of isolated locusts, and at 25–30 days there were no significant differences in the AKH content of the glands from crowded and isolated locusts.     

The inhibition of lipid synthesis in vitro in the locust, Schistocerca gregaria, by factors from the corpora cardiaca

ABSTRACT. The rate of lipid synthesis from [¹⁴C]acetate in fat body from Schistocerca americana gregaria has been studied in vitro. Maximum incorporation is found on days 6–10 in adults and day 4 of the fifth stadium. The label appeared in the fatty acid components of triacyl-glycerol, diacylglycerol and phospholipid.
Lipid synthesis in vitro was inhibited by extracts of corpora cardiaca, and such inhibition was most marked (up to 85%) in fat bodies from insects at stages where fatty acid synthesis was greatest. HPLC separation of corpora cardiaca extracts gave several active fractions of which the most active was adipokinetic hormone 1 (AKH-1).     

Preliminary characterization of glycogen phosphorylase activating hormone and adipokinetic hormone from Manduca sexta corpora cardiaca

ABSTRACT. An attempt was made to separate glycogen phosphorylase activating hormone (GPAH) and adipokinetic hormone (AKH) from the corpora cardiaca (CC) of the moth Manduca sexta (Lepidoptera: Sphingidae) by separating extracts of CC on various chromotographic media, but it was not possible to conclude whether GPAH and AKH are activities of one or of two different peptides. Both activities elute together from glass beads, from Sephadex G-25 and from Sephadex LH-20 columns. In the separation experiments with glass beads and G-25 the activities eluted as a single peak, but using LH-20 we found two peaks exhibiting both activities. The major peak eluted at 1.25 × V_t, which is very similar to locust AKH, while the smaller second peak eluted at O.74 × V _t. Cross injections of CC extracts from M. sexta into Locusta migratoria and CC extracts from L. migratoria into M. sexta suggest that GPAH and the AKH from M. sexta are not identical with the decapeptide AKH from locusts.     

Substrate utilization and flight speed during tethered flight in the locust

Mature laboratory locusts normally exhibit a characteristic pattern of change in flight speed with time. They fly at high speed for the first few minutes, during which carbohydrate forms the major fuel, but then slow to a cruising speed when lipid is used almost exclusively. Locusts flown for 30 min, rested for 2hr, and then reflown, exhibit an identical pattern of flight, even though they oxidise only half the amount of carbohydrate used in the first flight. The injection of adipokinetic hormone before the first flight elicits a low initial flight speed for 10 to 15 min but then the locusts accelerate to a constant higher speed. The injection of hormone before the second flight, when blood lipid levels are already high, reduces the utilization of carbohydrate by the flight muscles dramatically but results in constant high-speed flight.     

Rapid in vitro activation of corpora allata by extracted locust brain allatotropic factor

Brains of young (newly emerged) adult female locusts (Locusta migratoria migratorioides) and of mature (> 9 days old) locusts contain an extractable allatotropic factor, soluble in 100% methanol and in distilled water. This factor stimulates juvenile hormone III (JH III) synthesis and release from corpora allata (CA) that have been excised from donor locusts and then incubated with (radiolabeled methyl)-methionine in vitro in its presence. In addition to JH III, which is the major product synthesized by the CA, other hexanesoluble, radiolabeled compounds–-more polar than JH III–-are also released when CA are incubated in vitro. The activation of CA by the allatotropic factor is rapid and quickly declines when the factor is removed from the medium. Corpora allata excised from young females are marginally active and can be activated by brain allatotropic factor to less of an extent than CA of mature locusts. The content of allatotropic factor in brains of mature locusts is higher than that ascertained in brains of young females. Allatotropic factor is also present in the corpora cardiaca.     

Neuroparsin: A new energetic neurohormone in the African locust

The effects of neuroparsins on hemolymph trehalose and lipid levels and on total glycogen content were analyzed in Locusta migratoria. Saline and methanol extracts of the two lobes of the corpora cardiaca were assayed. Neuroparsins (A and B) were demonstrated to be hypertrehalosemic and hyperlipemic proteins of the neural lobe. Both of these metabolic activities of neuroparsins were somewhat less potent than those of adipokinetic hormone (AKH). Neuroparsin activity could be distinguished from AKH by blockage with an antiserum specific to neuroparsin. The hypertrehalosemic response induced by neuroparsins, in contrast to that of AKH, appeared to occur without a decrease of total glycogen content. The differential modes of action of AKH and neuroparsins could contribute to the fine modulation of carbohydrate metabolism in Locusta migratoria.     

Hypertrehalosaemic activity in corpus cardiacum-corpus allatum-aorta complex and adipokinetic response of Glossina morsitans

Abstract. Extracts from the corpus cardiacum-corpus allatum-aorta (CC-CA-A) complex of Glossina morsitans morsitans Westwood contain a hypertrehalosaemic factor when assayed in Periplaneta americana L. and in G.morsitans. A slight though significant decrease, followed by an increase, in haemolymph total carbohydrate occurs when tsetse are flown for 1 h. When assayed in Locusta migratoria L., the extracts have no adipokinetic activity, but L.migratoria corpus cardiacum extract produces an adipokinetic response in the female tsetse. It is suggested that the neurosecretions contained in the tsetse CC-CA-A complex contain a hypertrehalosaemic factor whose role is to mobilize glycogen.     

The adipokinetic hormone family in Chrysomeloidea: structural and functional considerations

The presented work is a hybrid of an overview and an original research paper on peptides belonging to the adipokinetic hormone (AKH) family that are present in the corpora cardiaca of Chrysomeloidea. First, we introduce the AKH/red pigment-concentrating hormone (RPCH) peptide family. Second, we collate the available primary sequence data on AKH peptides in Cerambycidae and Chrysomelidae, and we present new sequencing data (from previously unstudied species) obtained by liquid-chromatography coupled with ion trap electrospray ionisation mass spectrometry. Our expanded data set encompasses the primary structure of AKHs from seven species of Cerambycidae and three species of Chrysomelidae. All of these species synthesise the octapeptide code-named Peram-CAH-I (pGlu-Val-Asn-Phe-Ser-Pro-Asn-Trp amide). Whereas this is the sole AKH peptide in Cerambycidae, Chrysomelidae demonstrate a probable event of AKH gene duplication, thereby giving rise to an additional AKH. This second AKH peptide may be either Emppe-AKH (pGlu-Val-Asn-Phe-Thr-Pro-Asn-Trp amide) or Peram-CAH-II (pGlu-Leu-Thr-Phe-Thr-Pro-Asn-Trp amide). The peptide distribution and structural data suggest that both families are closely related and that Peram-CAH-I is the ancestral peptide. We hypothesise on the molecular evolution of Emppe-AKH and Peram-CAH-II from the ancestral peptide due to nonsynonymous missense single nucleotide polymorphism in the nucleotide coding sequence of prepro-AKH. Finally, we review the biological significance of the AKH peptides as hyperprolinaemic hormones in Chrysomeloidea, i.e. they cause an increase in the circulating concentration of proline. The mobilisation of proline has been demonstrated during flight in both cerambycid and chrysomelid beetles.     

Effects of adipokinetic hormone and its related peptide on maintaining hemolymph carbohydrate and lipid levels in the two-spotted cricket,Gryllus bimaculatus

Adipokinetic hormone (AKH) regulates energy homeostasis in insects by mobilizing lipid and carbohydrate from the fat body. Here, using RNA sequencing data, we identified cDNAs encoding AKH (GbAKH) and its highly homologous hormone AKH/corazonin-related peptide (GbACP) in the corpora cardiaca of the two-spotted cricket, Gryllus bimaculatus. RT-PCR revealed that GbAKH and GbACP are predominantly expressed in the corpora cardiaca and corpora allata, respectively. Phylogenetic analysis confirmed that the identified GbAKH and GbACP belong to the clades containing other AKHs and ACPs, respectively. Injection of synthetic GbAKH and GbACP elevated hemolymph carbohydrate and lipid levels and reduced food intake significantly. In contrast, knockdown of GbAKH and GbACP by RNA interference increased the food intake, although hemolymph lipid level was not altered. Collectively, this study provides evidence that ACP regulates hemolymph carbohydrate and lipid levels in cricket, possibly collaborative contribution with AKH to the maintenance of energy homeostasis.     

Separation and characteristics of antidiuretic factors from the corpora cardiaca of the migratory locust

Summary

Corpora cardiaca (CC) of the migratory locust contain two antidiuretic (AD) factors increasing the fluid reabsorption of isolated recta over a 5-h period.

They are contained in storage lobes (SL) and glandular lobes (GL) of the CC. They differ in size and can be separated from each other in different ways (extraction, dialysis, electrophoresis).

The AD factor contained in GL of the CC is stable at 4°C and quickly destroyed at 100°C. It stimulates the fluid reabsorption in a dose-dependent manner. Its release into the haemolymph seems to be controlled by octopamine, which is probably synthesized in the lateral neurosecretory areas of the brain.     

Hormonal control of lipid synthesis in the fat body of the adult female tsetse fly, Glossina morsitans

Aqueous extracts of brain, thoracic ganglion or corpora cardiaca of female Glossina morsitans were shown to contain a substance which inhibited the synthesis of lipid from l[U-¹⁴C] leucine by fat cells incubated in vitro. The highest concentration of this substance was found in the corpora cardiaca; approximately 1 × 10^?6 gland pairs μl^?1 were required for maximum inhibition. At concentrations greater than 1 × 10^?4 gland pairs μl^?1 the lipid synthesis inhibiting factor (hereafter referred to as the LSIF) was inactivated by the presence of a substance which could be removed by gel filtration. The concentration of LSIF in the corpora cardiaca and midbrain varied throughout the reproductive cycle of the female. Net release of LSIF from the midbrain occurred between the 2nd and 7th day of the 9-day reproductive cycle. Net release from the corpora cardiaca began on day 5 and continued until the end of the interlarval period on day 9. Results are consistent with the hypothesis that LSIF is synthesised mainly in the medial neurosecretory cells of the midbrain whereas the corpora cardiaca are the site of storage and release into the haemolymph. LSIF was present in midbrain and corpora cardiaca extracts from male G. morsitans but at lower concentrations than in females. No variation in LSIF concentration could be correlated with the feeding cycle. LSIF activity was not detected in fresh haemolymph but was found at high concentration in boiled haemolymph, suggesting the presence of an inhibitor which was inactivated at high temperature. Preliminary investigations into the nature of LSIF have shown it to be inactivated by proteolytic enzymes and to be recoverable in a single peak from a Sephadex G15 column.Results support the view that LSIF is a peptide hormone which, in conjunction with an inhibitor, controls the lipid synthetic ability of the fat cells of the adult female tsetse fly throughout the reproductive cycle.     

Adipokinetic and hyperglycaemic factor(s) in the corpora cardiaca/corpora allata complex of the stick insect, Carausius morosus.

ABSTRACT. The neurosecretory corpora cardiaca/corpora allata complex of Carausius morosus , a wingless insect of the superorder Orthopteroidea, contains adipokinetic and hyperglycaemic factor(s) capable of elevating lipids in locusts, and carbohydrates in cockroaches. Neither activity can be demonstrated in the stick insect itself, however. In addition, in locusts the Carausius gland extract is able to elevate levels of cyclic AMP in the fat body.     

Activation of fat body glycogen phosphorylase in Locusta migratoria by corpus cardiacum extract and synthetic adipokinetic hormone

Between 10 and 20 per cent of the total glycogen phosphorylase in the fat body of mature Locusta migratoria of both sexes is in the active form. Injection of an aqueous corpus cardiacum (CC) extract results in a rapid activation: within 2 min the level of active phosphorylase is significantly increased and full activation is reached within 10 to 20 min. As little as 0.002 CC gland equivalents stimulate fat body glycogen phosphorylase significantly and maximum activation is obtained with 0.05 CC gland equivalents. From experiments with known quantities of injected synthetic adipokinetic hormone (SAKH), it appears that this hormone cannot account for all the activation. This is supported by results obtained when extracts of carefully isolated storage lobes are injected; at the dose used here these have no adipokinetic activity, but activate fat body phosphorylase. Furthermore, when locusts are ‘stressed’ by rotation, although no adipokinetic hormone is released, an activation of phosphorylase occurs. Starvation causes also an increase in the active form of the enzyme. The fat body receptor sites of the locust recognise also the crustacean red pigment concentrating hormone (RPCH), whose structure closely resembles that of the locust adipokinetic hormone, leading to activation of the phosphorylase. However, RPCH is about 2.5–5 times less potent than SAKH. Crude CC extracts of a stick insect (Carausius morosus), a cockroach (Periplaneta americana) and the tobacco hornworm (Manduca sexta) activate locust fat body phosphorylase, although this last extract has no effect on lipid elevation. On the other hand, CC extracts of the death's head hawk moth (Acherontia atropos) and purified crustacean hyperglycaemic hormone from a crayfish (Orconectes limosus) have no effect.     

The role of the frontal ganglion and corpora cardiaca/corpora allata complex in post-feeding weight loss in adult Heliothis zea

Abstract A post-feeding diuretic response has been observed in adult Heliothis zea (Boddie) (Lepidoptera: Noctuidae). 2-day-old starved adults which were allowed to feed to repletion on a 10% (w/v) sucrose solution lost 49.1% (females) and 85.8% (males) of the weight of the ingested meal during the first hour following feeding. Ligation between head and thorax or frontal ganglionectomy, when performed immediately following feeding, each resulted in a significant and permanent reduction in this normal weight-loss. Injection of homogenates of the corpora cardiaca/corpora allata (CC/CA) complex into non-ligated insects immediately after feeding also reduced significantly the post-feeding weight-loss, but this inhibition was transient and disappeared after 1 h. Dissection and weighing of the crop from either ligated, frontal ganglionectomized, or CC/CA-injected insects confirmed the crop as the predominant site of fluid retention in each case. We suggest that a soluble antidiuretic factor from the CC/CA acts in conjunction with the frontal ganglion to control the rate of crop emptying and subsequent diuresis by regulating the volume of ingested fluid that is passed into the haemolymph from the crop/midgut.     

Adipokinetic hormone of the true armyworm, Pseudaletia unipuncta: immunohistochemistry, amino acid analysis, quantification and bioassay

Abstract A cluster of five to seven AKH-like immunoreactive cells lie in each lobe of the paired corpora cardiaca of the true armyworm, Pseudaletia unipuncta. These cells form a mesh work of immunoreactive processes within the corpora cardiaca, and immunoreactive tracts projecting posteriorly over the aorta.
Reversed-phase high performance liquid chromatography of extracts of the corpora cardiaca of P.unipuncta revealed a single large U.V. absorbent peak with a retention time identical to synthetic Manduca- AKH. Amino acid analysis of the contents of this peak yielded a composition identical to that of synthetic Manduca-AKH which was analysed in a parallel manner. Furthermore the material within the peak possessed adipokinetic activity when bioassayed in day 2 adult male P. unipuncta. The corpora cardiaca of similar individuals were found to contain approximately 17.6ng (17.6pmol) of Manduca-AKH equivalents per pair.
Injection of Manduca-AKH into 2-day-old adult male P.unipuncta resulted in a dose-dependent elevation in haemolymph lipid levels with a maximum level of 80–90μmg/μl obtained with 5–10 ng of Manduca-AKH. Continuous flight also elevated haemolymph lipid levels in day 4 adult males with a significant elevation evident in the first samples taken after 15 min of flight and lipid levels plateauing at approximately 100 μg/μl by about 60 min of flight.     

Allatotropic and nervous control of corpora allata in the adult male loreyi leafworm, Mythimna loreyi (Lepidoptera: Noctuidae)

Allatotropic activity is found in methanolic extracts of the brain–suboesophageal ganglion (SOG)–corpora cardiaca (CC) complex from virgin males of Mythimna loreyi Duponchel (Lepidoptera, Noctuidae). Corpora allata (CA) from 6‐day‐old virgin males exhibit low rates of release of Juvenile Hormone (JH) acid (JHA) in vitro. Release of JHA can be activated by the addition of an extract of brain–SOG–CC complex in a dose‐dependent manner, and this allatotropic activation can be sustained consistently in the continuous presence of such extracts. Based on its trypsin sensitivity and heat stability, the allatotropic factor is most likely a peptide. The allatotropic activity is dependent on the concentration of calcium ions in the medium, with the highest activation achieved beyond 2 m m . The results of nerve transection experiments suggest that both nervi corporis allati I (NCA I) and NCA II are involved in mediating the allatotropic control of CA in vitro. Isolated CA alone show significantly higher rates of release of JHA than the intact brain–SOG–CC–CA complex during the first 3 h of incubation, but the release of JHA reaches almost the same range in both groups by the end of the fourth hour of incubation.