Allatostatin Receptor Research Articles

A Novel Peptidomimetic Insecticide: Dippu-AstR-Based Rational Design and Biological Activity of Allatostatin Analogs.

Insect neuropeptides play an essential role in regulating growth, development, reproduction, nerve conduction, metabolism, and behavior in insects; therefore, G protein-coupled receptors of neuropeptides are considered important targets for designing green insecticides. Cockroach-type allatostatins (ASTs) (FGLamides allatostatins) are important insect neuropeptides in Diploptera punctata that inhibit juvenile hormone (JH) synthesis in the corpora allata and affect growth, development, and reproduction of insects. Therefore, the pursuit of novel insecticides targeting the allatostatin receptor (AstR) holds significant importance. Previously, we identified an AST analogue, H17, as a promising candidate for pest control. Herein, we first modeled the 3D structure of AstR in D. punctata (Dippu-AstR) and predicted the binding mode of H17 with Dippu-AstR to study the critical interactions and residues favorable to its bioactivity. Based on this binding mode, we designed and synthesized a series of H17 derivatives and assessed their insecticidal activity against D. punctata. Among them, compound Q6 showed higher insecticidal activity than H17 against D. punctata by inhibiting JH biosynthesis, indicating that Q6 is a potential candidate for a novel insect growth regulator (IGR)-based insecticide. Moreover, Q6 exhibited insecticidal activity against Plutella xylostella, indicating that these AST analogs may have a wider insecticidal spectrum. The underlying mechanisms and molecular conformations mediating the interactions of Q6 with Dippu-AstR were explored to understand its effects on the bioactivity. The present work clarifies how a target-based strategy facilitates the discovery of new peptide mimics with better bioactivity, enabling improved IGR-based insecticide potency in sustainable agriculture.

Opiate Sensitivity in Fruit Flies

Substance use disorder is a debilitating clinical condition in which behavioral dependence results from biological, environmental, genetic, and psychosocial factors. An epidemic surrounding the use and abuse of opioids is ravaging the world. While considerable efforts have explored the social drivers of addiction, a deeper understanding of biological causes and genetic vulnerabilities, preventative interventions, and effective treatments, have all proven elusive. This perspective article aims to remind readers that addictive natural compounds such as cocaine, nicotine, cathinone, or morphine, evolved as defensive metabolites to deter insect herbivory. The molecular mechanisms underlying motivational seeking and learning/reward show remarkable conservation since their early emergence in bilateral metazoans. An extended coevolutionary arms race subsequently weaponized these compounds into disruptors of learning, motivation, and incentivized attention. When plant chemical defenses attack insect physiology, humans are rendered susceptible due to strong conservation in the underlying molecular machinery. This perspective addresses the paradox that opiates were shaped to target insect neuropharmacology, even though this taxon appears to lack the recognized opioid receptor clade of mammals. We argue that the link is to be found in the allatostatin receptor, a basal ortholog of opioid receptors. Moreover, preliminary evidence indicates that morphine reduces Drosophila feeding and locomotion, concordant with a purported role as a defensive compound reducing herbivory. An implementation via allatostatin-mediated mechanisms is likely. This research argues for a broader heuristic perspective of substance abuse and a recognition of the evolutionary constraints that have likely shaped the biological drivers of opioid sensitivity and of its behavioral targets.

Reduction of stress responses in honey bees by synthetic ligands targeting an allatostatin receptor

Honey bees are of great economic and ecological importance, but are facing multiple stressors that can jeopardize their pollination efficiency and survival. Therefore, understanding the physiological bases of their stress response may help defining treatments to improve their resilience. We took an original approach to design molecules with this objective. We took advantage of the previous identified neuropeptide allatostatin A (ASTA) and its receptor (ASTA-R) as likely mediators of the honey bee response to a biologically relevant stressor, exposure to an alarm pheromone compound. A first series of ASTA-R ligands were identified through in silico screening using a homology 3D model of the receptor and in vitro binding experiments. One of these (A8) proved also efficient in vivo, as it could counteract two behavioral effects of pheromone exposure, albeit only in the millimolar range. This putative antagonist was used as a template for the chemical synthesis of a second generation of potential ligands. Among these, two compounds showed improved efficiency in vivo (in the micromolar range) as compared to A8 despite no major improvement in their affinity for the receptor in vitro. These new ligands are thus promising candidates for alleviating stress in honey bees.

Chemogenetic inhibition of Phox2-expressing neurons in the commissural NTS decreases blood pressure in anesthetized spontaneously hypertensive rats

Interruption of the activity of neurons in the commissural portion of the nucleus of the solitary tract (cNTS) decreases blood pressure (BP) in experimental models of hypertension, such as the spontaneously hypertensive (SH) rat. To examine whether PHOX2B expressing cNTS neurons are involved in maintaining the elevated BP, we used replication-deficient viruses with a modified Phox2 binding site promoter to express the inhibitory chemogenetic allatostatin receptor or green fluorescent protein in the cNTS. Following administration of allatostatin, we observed a depressor and bradycardic response in anesthetized SH rats that expressed the allatostatin receptor. Injection of allatostatin did not affect BP or heart rate (HR) in control SH rats expressing green fluorescent protein in the cNTS. Immunohistochemistry showed that the majority of transduced cNTS neurons were PHOX2B-immunoreactive and some also expressed tyrosine hydroxylase. We conclude that in anesthetized SH rat, the Phox2B expressing cNTS neurons maintain elevated BP.

A Possible Role of Allatostatin C in Inhibiting Ecdysone Biosynthesis Revealed in the Mud Crab Scylla paramamosain

C-type allatostatins (C-type ASTs) are a family of structurally related neuropeptides found in a wide range of insects and crustaceans. To date, the C-type allatostatin receptor in crustaceans has not been deorphaned, and little is known about its physiological functions. In this study, we aimed to functionally define a C-type ASTs receptor in the mud crab, Scylla paramamosian. We showed that C-type ASTs receptor can be activated by ScypaAST-C peptide in a dose-independent manner and by ScypaAST-CCC peptide in a dose-dependent manner with an IC50 value of 6.683 nM. Subsequently, in vivo and in vitro experiments were performed to investigate the potential roles of ScypaAST-C and ScypaAST-CCC peptides in the regulation of ecdysone (20E) and methyl farnesoate (MF) biosynthesis. The results indicated that ScypaAST-C inhibited biosynthesis of 20E in the Y-organ, whereas ScypaAST-CCC had no effect on the production of 20E. In addition, qRT-PCR showed that both ScypaAST-C and ScypaAST-CCC significantly decreased the level of expression of the MF biosynthetic enzyme gene in the mandibular organ, suggesting that the two neuropeptides have a negative effect on the MF biosynthesis in mandibular organs. In conclusion, this study provided new insight into the physiological roles of AST-C in inhibiting ecdysone biosynthesis. Furthermore, it was revealed that AST-C family peptides might inhibit MF biosynthesis in crustaceans.

Structural and Functional Characterization of Allatostatin Receptor Type-C of Thaumetopoea pityocampa, a Potential Target for Next-Generation Pest Control Agents.

Insect neuropeptide receptors, including allatostatin receptor type C (AstR-C), a G protein-coupled receptor, are among the potential targets for designing next-generation pesticides that despite their importance in offering a new mode-of-action have been overlooked. Focusing on AstR-C of Thaumetopoea pityocampa, a common pest in Mediterranean countries, by employing resonance energy transfer-based methods, we showed Gαi/o coupling and β-arrestin recruitment of the receptor at sub-nanomolar and nanomolar ranges of the endogenous ligand, AST-C, respectively. Molecular docking and molecular dynamics simulation studies revealed the importance of extracellular loop 2 in AstRC/AST-C interaction, and a combination of in silico and in vitro approaches showed the substantial role of Q2716.55 in G protein-dependent activation of AstR-C possibly via contributing to the flexibility of the receptor's structure. The functional and structural insights obtained on T. pit AstR-C positively assist future efforts in developing environmentally friendly pest control agents that are needed urgently.

A Chemogenetic Tool that Enables Functional Neural Circuit Analysis

Chemogenetics enables manipulation of neuronal activity in experimental animals. While providing information about the transduced neuron expressing a ligand-activated molecule, chemogenetics does not provide understanding about the antecedent circuit that drives that neuron's activity. For current approaches, this is not feasible, because the activating molecules are not genetically encoded. The insect allatostatin/allatostatin receptor system, a highly specific, powerful inhibitory chemogenetic approach, has this advantage, because the ligand, being a peptide, is genetically encoded. We developed viral vector-based systems to express biologically active allatostatin in neurons invivo and allatostatin receptors in subpopulations of postsynaptic neurons. We demonstrate that activity-dependent release of allatostatin induces inhibition of allatostatin receptor-expressing neurons. We validate the approach in the vagal viscerosensory system where inhibitory, rather than the usual excitatory, viscerosensory input leads to sustained decreases in baroreceptor reflex sensitivity and bodyweight.

Comparison of Predicted Amino Acid Sequences of Allatotropin/Allatostatin Receptors from Solitary to Eusocial Bee Species (Hymenoptera, Apoidea)

Abstract An increasingly amount of evidence supports that the evolution of eusociality is accompanies by shifts in ancient molecular and physiological pathways. The juvenile hormone, one of the most important hormones in the post-embryonic development of insects, attracts the most attention in the context of social organization. Allatoregulatory neuropeptides (Allatotropin, Allatostatin-A and Allatostatin-C) are known to regulate juvenile hormone synthesis and release in insects. In order to clarify the transitions of juvenile hormone synthesis involved in eusocial evolution, the substitutions of amino acid residues and the complexity of post-translational modifications in allatoregulatory neuropeptide receptors were characterized. Both allatotropin and allatostatin receptors are identified in all examined bee species regardless if they are solitary or eusocial. Although the amino acid sequences are highly conserved, phylogenetic results are consistent with the eusocial status. The abundance of predicted post-translational modifications correlates with social complexity except for that in allatostatin-C receptors. Even though the consequences of these specific amino acid substitutions and various post-translational modification complexity have not been studied, they likely contribute to the localizing, binding and coupling characteristics of the receptor groups.

Allatostatin C modulates nociception and immunity in Drosophila

Bacterial induced inflammatory responses cause pain through direct activation of nociceptive neurons, and the ablation of these neurons leads to increased immune infiltration. In this study, we investigated nociceptive-immune interactions in Drosophila and the role these interactions play during pathogenic bacterial infection. After bacterial infection, we found robust upregulation of ligand-gated ion channels and allatostatin receptors involved in nociception, which potentially leads to hyperalgesia. We further found that Allatostatin-C Receptor 2 (AstC-R2) plays a crucial role in host survival during infection with the pathogenic bacterium Photorhabdus luminescens. Upon examination of immune signaling in AstC-R2 deficient mutants, we demonstrated that Allatostatin-C Receptor 2 specifically inhibits the Immune deficiency pathway, and knockdown of AstC-R2 leads to overproduction of antimicrobial peptides related to this pathway and decreased host survival. This study provides mechanistic insights into the importance of microbe-nociceptor interactions during bacterial challenge. We posit that Allatostatin C is an immunosuppressive substance released by nociceptors or Drosophila hemocytes that dampens IMD signaling in order to either prevent immunopathology or to reduce unnecessary metabolic cost after microbial stimulation. AstC-R2 also acts to dampen thermal nociception in the absence of infection, suggesting an intrinsic neuronal role in mediating these processes during homeostatic conditions. Further examination into the signaling mechanisms by which Allatostatin-C alters immunity and nociception in Drosophila may reveal conserved pathways which can be utilized towards therapeutically targeting inflammatory pain and chronic inflammation.

Role of ventral medullary catecholaminergic neurons for respiratory modulation of sympathetic outflow in rats

Sympathetic activity displays rhythmic oscillations generated by brainstem inspiratory and expiratory neurons. Amplification of these rhythmic respiratory-related oscillations is observed in rats under enhanced central respiratory drive or during development of neurogenic hypertension. Herein, we evaluated the involvement of ventral medullary sympatho-excitatory catecholaminergic C1 neurons, using inhibitory Drosophila allatostatin receptors, for the enhanced expiratory-related oscillations in sympathetic activity in rats submitted to chronic intermittent hypoxia (CIH) and following activation of both peripheral (hypoxia) and central chemoreceptors (hypercapnia). Pharmacogenetic inhibition of C1 neurons bilaterally resulted in reductions of their firing frequency and amplitude of inspiratory-related sympathetic activity in rats in normocapnia, hypercapnia or after CIH. In contrast, hypercapnia or hypoxia-induced enhanced expiratory-related sympathetic oscillations were unaffected by C1 neuronal inhibition. Inhibition of C1 neurons also resulted in a significant fall in arterial pressure and heart rate that was similar in magnitude between normotensive and CIH hypertensive rats, but basal arterial pressure in CIH rats remained higher compared to controls. C1 neurons play a key role in regulating inspiratory modulation of sympathetic activity and arterial pressure in both normotensive and CIH hypertensive rats, but they are not involved in the enhanced late-expiratory-related sympathetic activity triggered by activation of peripheral or central chemoreceptors.

Functional perturbation of forebrain principal neurons reveals differential effects in novel and well-learned tasks

Neural circuits in mammalian brains consist of large numbers of different cell types having different functional properties. To better understand the separate roles of individual neuron types in specific aspects of spatial learning and memory, we perturbed the function of principal neurons in vivo during maze performance or in hippocampal slices during recording of evoked excitatory synaptic potentials. Transgenic mice expressing the Drosophila allatostatin receptor (AlstR) in cortical and hippocampal pyramidal cells were tested on an elevated plus maze, in a Y-maze, and in the Morris water maze. Relative to a control cohort, AlstR-positive mice treated with allatostatin exhibited no difference in open arm dwell time on the elevated plus maze or total number of arm entries in a Y-maze, but displayed reduced spontaneous alternation. When animals received massed or spaced training trials in the Morris water maze, and the peptide was delivered prior to an immediate probe, no effects on performance were observed. When the peptide was delivered during a probe trial performed 24h after seven days of spaced training, allatostatin delivery to AlstR positive mice enhanced direct navigation to the escape platform. Combined, these results suggest that cortical and hippocampal pyramidal neurons are required during spatial decision-making in a novel environment and compete with other neural systems after extended training in a long-term reference memory task. In hippocampal slices collected from AlstR positive animals, allatostatin delivery produced frequency dependent alterations in the Schaffer collateral fiber volley (attenuated accommodation at 100Hz) and excitatory postsynaptic potential (attenuated facilitation at 5Hz). Combined, the neural and behavioral discoveries support the involvement of short-term plasticity of Schaffer collateral axons and synapses during exploration of a novel environment and during initial orientation to a goal in a well-learned setting.

Ligand binding pocket of a novel Allatostatin receptor type C of stick insect, Carausius morosus

Allatostatins (AST) are neuropeptides with variable function ranging from regulation of developmental processes to the feeding behavior in insects. They exert their effects by binding to cognate GPCRs, called Allatostatin receptors (AlstR), which emerge as promising targets for pesticide design. However, AlstRs are rarely studied. This study is the first reported structural study on AlstR-AST interaction. In this work, the first C type AlstR from the stick insect Carausius morosus (CamAlstR-C) was identified and its interaction with type C AST peptide was shown to be physically consistent with the experimental results. The proposed structure of CamAlstR-C revealed a conserved motif within the third extracellular loop, which, together with the N-terminus is essential for ligand binding. In this work, computational studies were combined with molecular and nano-scale approaches in order to introduce an unknown GPCR-ligand system. Consequently, the data obtained provided a reliable target region for future agonist/inverse agonist studies on AlstRs.

Origins of the vagal drive controlling left ventricular contractility.

Key points The strength, functional significance and origins of parasympathetic innervation of the left ventricle remain controversial.This study tested the hypothesis that parasympathetic control of left ventricular contractility is provided by vagal preganglionic neurones of the dorsal motor nucleus (DVMN).Under β‐adrenoceptor blockade combined with spinal cord (C1) transection (to remove sympathetic influences), systemic administration of atropine increased left ventricular contractility in rats anaesthetized with urethane, confirming the existence of a tonic inhibitory muscarinic influence on cardiac inotropy.Increased left ventricular contractility in anaesthetized rats was observed when DVMN neurones were silenced.Functional neuroanatomical mapping revealed that vagal preganglionic neurones that have an impact on left ventricular contractility are located in the caudal region of the left DVMN.These neurones provide functionally significant parasympathetic control of left ventricular inotropy. The strength, functional significance and origins of direct parasympathetic innervation of the left ventricle (LV) remain controversial. In the present study we used an anaesthetized rat model to first confirm the presence of tonic inhibitory vagal influence on LV inotropy. Using genetic neuronal targeting and functional neuroanatomical mapping we tested the hypothesis that parasympathetic control of LV contractility is provided by vagal preganglionic neurones located in the dorsal motor nucleus (DVMN). It was found that under systemic β‐adrenoceptor blockade (atenolol) combined with spinal cord (C1) transection (to remove sympathetic influences), intravenous administration of atropine increases LV contractility in rats anaesthetized with urethane, but not in animals anaesthetized with pentobarbital. Increased LV contractility in rats anaesthetized with urethane was also observed when DVMN neurones targeted bilaterally to express an inhibitory Drosophila allatostatin receptor were silenced by application of an insect peptide allatostatin. Microinjections of glutamate and muscimol to activate or inhibit neuronal cell bodies in distinct locations along the rostro‐caudal extent of the left and right DVMN revealed that vagal preganglionic neurones, which have an impact on LV contractility, are located in the caudal region of the left DVMN. Changes in LV contractility were only observed when this subpopulation of DVMN neurones was activated or inhibited. These data confirm the existence of a tonic inhibitory muscarinic influence on LV contractility. Activity of a subpopulation of DVMN neurones provides functionally significant parasympathetic control of LV contractile function.

Are C1 Neurons Involved in the Sympathetic Overactivity Induced by Chronic Intermittent Hypoxia?

Chronic intermittent hypoxia (CIH) produces expiratory‐related sympatho‐excitation in rats, which might contribute to the development of hypertension. We evaluated the role of sympatho‐excitatory cathecolaminergic medullary C1 neurons in the CIH‐induced expiratory‐related sympatho‐excitation and hypertension in rats. In awake rats in vivo and in in situ perfused preparations of rat, C1 neurons were acutely silenced by application of the insect peptide allatostatin following cell‐specific targeting with a lentiviral vector to express the inhibitory Drosophila allatostatin receptor in control and CIH rats (10 days). In awake rats in vivo, inhibition of ~ 72% of the C1 neurons resulted in a profound and similar fall in arterial pressure and heart rate in control (n=12) and CIH rats (n=12). However, CIH rats still presented elevated arterial pressure after C1 inhibition (p<0.05). In in situ, C1 inhibition resulted in reversible reductions of perfusion pressure, amplitude of inspiratory‐related bursts of thoracic sympathetic nerve and C1 pre‐sympathetic neurons activities in control (n=7) and CIH (n=9) rats. However, CIH‐ (n=9), acute hypoxia‐ (n=7) or CO2‐induced expiratory‐related sympatho‐excitation (n=10) were not affected by C1 inhibition. These data confirm a physiological role of C1 neurons in generating baseline sympathetic activity and arterial pressure. However, C1 neurons apparently are not involved in the expiratory‐related sympatho‐excitation and hypertension induced by CIH.Support or Funding InformationFAPESP and CNPQ

RXR/USP and EcR are critical for the regulation of reproduction and the control of JH biosynthesis in Diploptera punctata

During development and reproduction the response to ecdysteroids is mediated by a heterodimeric receptor complex comprising the retinoid X receptor/ultraspiracle (RXR/USP) and the ecdysone receptor (EcR). Here, the role of these receptors in the endocrine control of reproduction is examined in the cockroach Diploptera punctata. We report the sequence of four DpRXR and three DpEcR splice variants, including the first description of a Drosophila EcRB2-like isoform in a hemimetabolous insect. DpRXR and DpEcR are broadly expressed in the tissues of adult females, with relatively high transcript levels in the corpora allata (CA), nervous tissue and ovary. Developmental profiling revealed an inverse correlation between DpRXR and DpEcR expression and the activity of the CA. RNAi-mediated depletion of DpRXR and DpEcR did not affect oocyte growth, but inhibited oviposition and impaired chorion formation. Retained oocytes exhibited a degenerating follicular epithelium and were slowly resorbed. Treated animals showed significantly higher rates of JH biosynthesis and a decrease in ecdysteroid titers at the end of vitellogenesis. Reduction of DpRXR and DpEcR expression resulted in an upregulation of genes involved in JH production and a downregulation of allatostatin receptor mRNA in the CA. Treatment with dsRNA also affected the expression of genes downstream of JH in target tissues including vitellogenin and Krüppel-homolog 1 as well as Broad-Complex, an early ecdysone response gene. Overall, results suggest that DpRXR and DpEcR are not required early in the reproductive cycle when events are JH-dependent, but do mediate critical ecdysteroid feedback to the CA late in the gonadotropic cycle.

Putative brain neuropeptidome of the Malaria Vector Anopheles albimanus and differential expression during the infection with Plasmodium berghei.

Event Abstract Back to Event Putative brain neuropeptidome of the Malaria Vector Anopheles albimanus and differential expression during the infection with Plasmodium berghei. Alejandro A. Delgado1*, Mario Henry Rodríguez-López1, Juan Mauricio Télez.Sosa1, Jesús Martínez-Barnetche1, Rosa Elena Gómez-Barreto1, Jorge Luis Ocampo-Bahena2, Guillermo Perales-Ortiz1, Ken Morán-Francia3, María Del Carmen Rodríguez-Gutiérrrez1 and Humberto Lanz-Mendoza1 1 Instituto Nacional de Salud Pública , Centro de Investigación Sobre Enfermedades Infecciosas, Mexico 2 Universidad Politécnica de Morelos, Mexico 3 Universidad Autonoma del Estado de Morelos, Mexico Insect’s neuropeptides are mainly synthesized in the brain as neuromodulators and neurohormones and play a central role in the control of most physiological processes. In this work, using a high-throughput strategy and in silico analysis of Anopheles albimanus and Anopheles gambiae transcriptomes, we identified a putative neuropeptidome of Anopheles albimanus mosquito brain. Nineteen peptide transcripts were found that predicted at least forty-four bio-peptides. When we analyzed expression of tachykinins, pyrokinins, myosuppressins, adipokinetic hormone II and SIFamide by qPCR, we observed over-expression of pyrokinins and AKH II transcripts of coming from An. albimanus’s brains infected with P. berghei. When these transcripts were analyzed in other tissues, myosuppresin was the only neuropeptide over-expressed in the midguts after the infection with the parasite. Analyses of string-type interaction suggest that neuropeptides could co-participate with neuropeptides or neuropeptides receptors like CCAPr, AKHr, SIFa, Allatostatin, PDFr, diuretic hormones, FMRFamides and pyrokinin receptor of the parasite/mosquito interaction. These data will serve to further understanding the role of neuropeptides in the physiology of the mosquito and continue studies of their probable participation in processes of interaction Anopheles spp-Plasmodium spp. Keywords: Neuropeptides, SIFamide, Tachycardia, pyrokinin insects, adipokinetic hormone, myosuppressin Conference: IMMUNOCOLOMBIA2015 - 11th Congress of the Latin American Association of Immunology - 10o. Congreso de la Asociación Colombiana de Alergia, Asma e Inmunología, Medellin, Colombia, 13 Oct - 16 Oct, 2015. Presentation Type: Poster Presentation Topic: Infectious and parasitic diseases Citation: Delgado AA, Rodríguez-López M, Télez.Sosa J, Martínez-Barnetche J, Gómez-Barreto R, Ocampo-Bahena J, Perales-Ortiz G, Morán-Francia K, Rodríguez-Gutiérrrez M and Lanz-Mendoza H (2015). Putative brain neuropeptidome of the Malaria Vector Anopheles albimanus and differential expression during the infection with Plasmodium berghei.. Front. Immunol. Conference Abstract: IMMUNOCOLOMBIA2015 - 11th Congress of the Latin American Association of Immunology - 10o. Congreso de la Asociación Colombiana de Alergia, Asma e Inmunología. doi: 10.3389/conf.fimmu.2015.05.00379 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 14 Apr 2015; Published Online: 17 Sep 2015. * Correspondence: Prof. Alejandro A Delgado, Instituto Nacional de Salud Pública, Centro de Investigación Sobre Enfermedades Infecciosas, Cuernavaca, Morelos, 621000, Mexico, adelgado@insp.mx Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers Alejandro A Delgado Mario Henry Rodríguez-López Juan Mauricio Télez.Sosa Jesús Martínez-Barnetche Rosa Elena Gómez-Barreto Jorge Luis Ocampo-Bahena Guillermo Perales-Ortiz Ken Morán-Francia María Del Carmen Rodríguez-Gutiérrrez Humberto Lanz-Mendoza Google Alejandro A Delgado Mario Henry Rodríguez-López Juan Mauricio Télez.Sosa Jesús Martínez-Barnetche Rosa Elena Gómez-Barreto Jorge Luis Ocampo-Bahena Guillermo Perales-Ortiz Ken Morán-Francia María Del Carmen Rodríguez-Gutiérrrez Humberto Lanz-Mendoza Google Scholar Alejandro A Delgado Mario Henry Rodríguez-López Juan Mauricio Télez.Sosa Jesús Martínez-Barnetche Rosa Elena Gómez-Barreto Jorge Luis Ocampo-Bahena Guillermo Perales-Ortiz Ken Morán-Francia María Del Carmen Rodríguez-Gutiérrrez Humberto Lanz-Mendoza PubMed Alejandro A Delgado Mario Henry Rodríguez-López Juan Mauricio Télez.Sosa Jesús Martínez-Barnetche Rosa Elena Gómez-Barreto Jorge Luis Ocampo-Bahena Guillermo Perales-Ortiz Ken Morán-Francia María Del Carmen Rodríguez-Gutiérrrez Humberto Lanz-Mendoza Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. 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Identification and functional characterization of FGLamide-related allatostatin receptor in Rhodnius prolixus

FGLamide-related ASTs (FGLa/ASTs) are a family of brain/gut peptides with numerous physiological roles, including inhibition of juvenile hormone (JH) biosynthesis by the corpora allata and inhibition of visceral muscle contraction. FGLa/ASTs mediate their effects by binding to a rhodopsin-like G-protein coupled receptor that is evolutionarily related to the vertebrate galanin receptor. Here we determine the cDNA sequence encoding FGLa/AST receptor (FGLa/AST-R) from the Chagas disease vector, Rhodnius prolixus (Rhopr-FGLa/AST-R), determine its spatial expression pattern using quantitative PCR and functionally characterize the receptor using a heterologous assay. Our expression analysis indicates that Rhopr-FGLa/AST-R is highly expressed in the central nervous system. The receptor is also expressed in various peripheral tissues including the dorsal vessel, midgut, hindgut and reproductive tissues of both males and females, suggesting a role in processes associated with feeding and reproduction. The possible involvement of Rhopr-FGLa/ASTs in the inhibition of JH biosynthesis is also implicated due to presence of the receptor transcript in the R. prolixus corpora cardiaca/corpora allata complex. The functional assay showed that various Rhopr-FGLa/ASTs activate the receptor, with EC50 values for the response in the nanomolar range. Moreover, Rhopr-FGLa/AST-R can couple with Gq alpha subunits and cause an increase in intracellular calcium concentration. Lastly, we tested various FGLa/AST analogs in our heterologous assay. These compounds also activated the receptor and thus have the potential to serve as insect growth regulators and aid in pest control.

14 * Acute and chronic withdrawal of dorsal vagal preganglionic activity in the central nervous system predisposes to ventricular arrhythmia

Introduction: Electrical stimulation of the vagus nerve has been shown to protect against ventricular tachyarrhythmia (VT). The exact mechanism of this effect is unknown and it also remains unclear whether acute or chronic withdrawal of tonic vagal efferent activity to the heart predisposes the heart to VT. To investigate this, we acutely silenced the vagal preganglionic neurones in the dorsal motor nucleus of the vagus nerve (DVMN) in a rat model using a pharmogenetic approach, and we used the triple-synuclein-null mice as a model of autonomic dysfunction associated with chronic reduction of vagal tone. Methods: In 12 male Sprague-Dawley rats (380-420g), lentiviral vectors were used to transduce DVMN neurones to express an inhibitory Gi-protein-coupled Drosophila allatostatin receptor (AlstR) or green fluorescent protein as a control. Application of a natural ligand of AlstR - an insect peptide allatostatin (5 µl) produces selective and rapid silencing of targeted neurones. To investigate the role of age-dependent autonomic dysfunction, 7 young (2-3 months) and 8 old (12-16 months) wild type (WT) and triple-synuclein-null (TKO) mice were studied. The animals underwent programmed electrical stimulation of the right ventricle under urethane anaesthesia (1.3g/kg) to obtain ventricular effective refractory period (VERP). Ventricular tachycardia (VT) inducibility by burst pacing was also assessed in the acute rat models. Results: Acute inhibition of the DVMN vagal preganglionic neurones in rats resulted in shortening of the VERP (32.6±0.8 vs 41.5±0.5 ms; p=0.002) and lowered VT threshold on burst pacing (21.7±4.2 vs 44.4±8.9 Hz; p=0.043). Young TKO mice showed no difference in VERP (37.0±5.2 vs 37.0±3.1 ms). However, development of autonomic dysfunction in older TKO mice was associated with a reduction in VERP (30.6±2.3 vs 43.4±2.3 ms; p=0.003). In old WT animals, systemic administration of methylatropine (2mg/kg) mimicked the pro-arrhythmic phenotype of synuclein deficiency with significant VERP shortening (31.0±2.6 vs 43.4±2.3 ms; p=0.004). Conclusion: This study demonstrates that both acute and chronic decrease in activity of a distinct population of vagal preganglionic neurones in the DVMN predisposes the heart to ventricular arrhythmia by reduction of the effective refractory period. CNS disorders associated with autonomic dysfunction (mimicked here by synuclein deficiency) and decreased DVMN activity may lead to pro-arrhythmic phenotype.

Mode of action of allatostatins in the regulation of juvenile hormone biosynthesis in the cockroach, Diploptera punctata

The FGLamide allatostatins (FGL/ASTs) are a family of neuropeptides with pleiotropic functions, including the inhibition of juvenile hormone (JH) biosynthesis, vitellogenesis and muscle contraction. In the cockroach, Diploptera punctata, thirteen FGLa/ASTs and one allatostatin receptor (AstR) have been identified. However, the mode of action of ASTs in regulation of JH biosynthesis remains unclear. Here, we determined the tissue distribution of Dippu-AstR. And we expressed Dippu-AstR in vertebrate cell lines, and activated the receptor with the Dippu-ASTs. Our results show that all thirteen ASTs activated Dippu-AstR in a dose dependent manner, albeit with different potencies. Functional analysis of AstR in multiple cell lines demonstrated that activation of the AstR receptor resulted in elevated levels of Ca2+ and cAMP, which suggests that Dippu-AstR can act through the Gαq and Gαs protein pathways. The study on the target of AST action reveals that FGL/AST affects JH biosynthesis prior to the entry of acetyl-CoA into the JH biosynthetic pathway.

Neuropeptidergic control of the hindgut in the black-legged tick Ixodes scapularis

The hindgut, as a part of the tick excretory system, plays an important physiological role in maintaining homoeostases and waste elimination. Immunoreactive projections from the synganglion to the hindgut were found using antibodies against four different neuropeptides: FGLamide related allatostatin, myoinhibitory peptide, SIFamide, and orcokinin. The presence of FGLamide related allatostatin, myoinhibitory peptide and SIFamide in both synganglia (source) and hindgut (target organ) extracts was confirmed by MALDI-TOF. Tissue-specific PCR revealed the expression of four putative FGLamide related allatostatin receptors and an SIFamide receptor in the hindgut. An antibody against Ixodes scapularis SIFamide receptor detected immunoreactive spots in epithelial cells as well as the visceral muscles surrounding the rectal sac, while staining with the antibody against myoinhibitory peptide receptor 1 revealed that the immunoreactivity was only associated with the visceral muscles. In hindgut motility assays, SIFamide activated hindgut motility in a dose-dependent manner. None of other three neuropeptides (FGLamide related allatostatin, myoinhibitory peptide and orcokinin) activated hindgut motility when tested alone. Myoinhibitory peptide antagonised the SIFamide-stimulated hindgut mobility when it was tested in combination with SIFamide.