RESUMEN
Circadian (approximately daily) rhythms pervade mammalian behavior. They are generated by cell-autonomous, transcriptional/translational feedback loops (TTFLs), active in all tissues. This distributed clock network is coordinated by the principal circadian pacemaker, the hypothalamic suprachiasmatic nucleus (SCN). Its robust and accurate time-keeping arises from circuit-level interactions that bind its individual cellular clocks into a coherent time-keeper. Cells that express the neuropeptide vasoactive intestinal peptide (VIP) mediate retinal entrainment of the SCN; and in the absence of VIP, or its cognate receptor VPAC2, circadian behavior is compromised because SCN cells cannot synchronize. The contributions to pace-making of other cell types, including VPAC2-expressing target cells of VIP, are, however, not understood. We therefore used intersectional genetics to manipulate the cell-autonomous TTFLs of VPAC2-expressing cells. Measuring circadian behavioral and SCN rhythmicity in these temporally chimeric male mice thus enabled us to determine the contribution of VPAC2-expressing cells (â¼35% of SCN cells) to SCN time-keeping. Lengthening of the intrinsic TTFL period of VPAC2 cells by deletion of the CK1εTau allele concomitantly lengthened the period of circadian behavioral rhythms. It also increased the variability of the circadian period of bioluminescent TTFL rhythms in SCN slices recorded ex vivo Abrogation of circadian competence in VPAC2 cells by deletion of Bmal1 severely disrupted circadian behavioral rhythms and compromised TTFL time-keeping in the corresponding SCN slices. Thus, VPAC2-expressing cells are a distinct, functionally powerful subset of the SCN circuit, contributing to computation of ensemble period and maintenance of circadian robustness. These findings extend our understanding of SCN circuit topology.
Asunto(s)
Conducta Animal/fisiología , Ritmo Circadiano/fisiología , Periodicidad , Receptores de Tipo II del Péptido Intestinal Vasoactivo/fisiología , Receptores de Péptido Intestinal Vasoactivo/fisiología , Factores de Transcripción ARNTL/genética , Factores de Transcripción ARNTL/fisiología , Animales , Ritmo Circadiano/genética , Retroalimentación Fisiológica , Masculino , Ratones , Ratones Noqueados , Actividad Motora/fisiología , Proteínas Mutantes Quiméricas/genética , Receptores de Péptido Intestinal Vasoactivo/genética , Receptores de Tipo II del Péptido Intestinal Vasoactivo/genética , Núcleo Supraquiasmático/fisiologíaRESUMEN
Using molecular, biochemical, and cytological tools, we studied the nucleotide and the deduced amino acid sequence of PHI/VIP and the distribution of VIP/VPAC receptor system in the testis of the Italian wall lizard Podarcis sicula to evaluate the involvement of such a neuropeptide in the spermatogenesis control. We demonstrated that (1) Podarcis sicula VIP had a high identity with other vertebrate VIP sequences, (2) differently from mammals, VIP was synthesized directly in the testis, and (3) VIP and its receptor VPAC2 were widely distributed in germ and somatic cells, while the VPAC1 R had a distribution limited to Leydig cells. Our results demonstrated that in Podarcis sicula the VIP sequence is highly preserved and that this neuropeptide is involved in lizard spermatogenesis and steroidogenesis.
Asunto(s)
Lagartos/fisiología , Receptores de Péptido Intestinal Vasoactivo/fisiología , Testículo/fisiología , Péptido Intestinal Vasoactivo/fisiología , Secuencia de Aminoácidos , Animales , Secuencia de Bases , Clonación Molecular , Secuencia Conservada , Hibridación in Situ , Células Intersticiales del Testículo/química , Células Intersticiales del Testículo/fisiología , Masculino , Datos de Secuencia Molecular , Reacción en Cadena en Tiempo Real de la Polimerasa , Receptores de Péptido Intestinal Vasoactivo/análisis , Receptores de Péptido Intestinal Vasoactivo/genética , Receptores de Tipo II del Péptido Intestinal Vasoactivo/análisis , Receptores de Tipo II del Péptido Intestinal Vasoactivo/genética , Receptores de Tipo II del Péptido Intestinal Vasoactivo/fisiología , Receptores de Tipo I del Polipéptido Intestinal Vasoactivo/análisis , Receptores de Tipo I del Polipéptido Intestinal Vasoactivo/genética , Receptores de Tipo I del Polipéptido Intestinal Vasoactivo/fisiología , Alineación de Secuencia , Testículo/química , Péptido Intestinal Vasoactivo/análisis , Péptido Intestinal Vasoactivo/genéticaRESUMEN
In both mammals and birds, vasoactive intestinal polypeptide (VIP) neurons and fibers are present in virtually every brain area that is important for social behavior. VIP influences aggression in birds, social recognition in rodents, and prolactin secretion in both taxa, but other possible functions in social modulation remain little explored. VIP effects are mediated by VPAC receptors, which bind both VIP and pituitary adenylate cyclase activating peptide. Within the lateral septum and medial bed nucleus of the stria terminalis, VPAC receptors are found at higher densities in gregarious finch species relative to territorial species, suggesting that VPAC receptor activation promotes social contact and/or preference for larger groups. Here we here test this hypothesis in zebra finches (Taeniopygia guttata), and also examine the relevance of VPAC receptors to anxiety-like processes. Intraventricular infusions of the VPAC receptor antagonist, neurotensin6-11 mouseVIP7-28, strongly reduce social contact when animals are tested in a novel environment, and exert sex-specific effects on grouping behavior. Specifically, VPAC receptor antagonism reduces gregariousness in females but increases gregariousness in males. Interestingly, VPAC antagonism in the medial pallium (putative prefrontal cortex homologue) significantly reduces gregariousness in both sexes, suggesting site-specific effects of VIP signaling. However, VPAC antagonism does not modulate novel-familiar social preferences in a familiar environment or general anxiety-like behaviors. The current results suggest that endogenous activation of VPAC receptors promotes social contact under novel environmental conditions, a function that may be accentuated in gregarious species. Moreover, endogenous VIP modulates gregariousness in both males and females.
Asunto(s)
Conducta Animal/fisiología , Conducta Exploratoria/fisiología , Pinzones/fisiología , Neurotensina/farmacología , Corteza Prefrontal/efectos de los fármacos , Receptores de Péptido Intestinal Vasoactivo/fisiología , Conducta Social , Péptido Intestinal Vasoactivo/farmacología , Animales , Ansiedad/fisiopatología , Conducta Animal/efectos de los fármacos , Ambiente , Conducta Exploratoria/efectos de los fármacos , Femenino , Masculino , Corteza Prefrontal/fisiología , Receptores de Péptido Intestinal Vasoactivo/antagonistas & inhibidores , Proteínas Recombinantes de Fusión/farmacología , Transducción de Señal/efectos de los fármacos , Transducción de Señal/fisiología , Péptido Intestinal Vasoactivo/análogos & derivados , Péptido Intestinal Vasoactivo/antagonistas & inhibidoresRESUMEN
BACKGROUND: Vasoactive intestinal peptide (VIP) and pituitary adenylate cyclase activating peptide (PACAP)-containing nerves surround cerebral blood vessels. The peptides have potent vasodilator properties via smooth muscle cell receptors and activation of adenylate cyclase. The purpose of this study was to describe the effects of two putative VIP/PACAP receptor antagonists and the distribution of the receptor protein in rat brain vessels. METHODS: The vascular effects of VIP, PACAP-27 and PACAP-38 were investigated in segments of rat middle cerebral artery (MCA) by pressurized arteriography, and in a wire myograph. The antagonistic responses to PACAP6-38 and PG99-465 were evaluated. In addition, the receptor subtypes for VIP and PACAP (VPAC1, VPAC2 and PAC1) were visualized in the rat middle cerebral artery by immunohistochemistry and Western blotting. RESULTS: In the perfusion model, abluminal but not luminal VIP, PACAP-27 and PACAP-38 caused concentration-dependent relaxations of the MCA (27.1±0.2%, 25.2±0.4% and 0.3±0.1%, respectively). In the wire myograph, there was no significant difference in potency of the peptides in the MCA. In both systems, PACAP6-38 and PG99-465 inhibited the VIP induced relaxation. Western blot showed the presence of the receptor proteins in cerebral vasculature and immunohistochemistry showed that all three receptors are present and located in the cytoplasm of smooth muscle cells. CONCLUSION: In both systems, the two blockers antagonized the relaxant VIP effect; the potency order of agonists and the immunohistochemistry suggest the presence of the dilatory VPAC1 and VPAC2 receptors on the smooth muscle cells.
Asunto(s)
Calcio/fisiología , Arterias Cerebrales/metabolismo , Receptores del Polipéptido Activador de la Adenilato-Ciclasa Hipofisaria/fisiología , Receptores de Péptido Intestinal Vasoactivo/fisiología , Ácido 15-Hidroxi-11 alfa,9 alfa-(epoximetano)prosta-5,13-dienoico/farmacología , Angiografía , Animales , Western Blotting , Arterias Cerebrales/efectos de los fármacos , Electromiografía , Técnica del Anticuerpo Fluorescente , Inmunohistoquímica , Contracción Isométrica/efectos de los fármacos , Masculino , Músculo Liso Vascular/fisiología , ARN Mensajero/biosíntesis , ARN Mensajero/genética , Ratas , Ratas Sprague-Dawley , Ratas Wistar , Receptores del Polipéptido Activador de la Adenilato-Ciclasa Hipofisaria/efectos de los fármacos , Receptores del Polipéptido Activador de la Adenilato-Ciclasa Hipofisaria/metabolismo , Receptores de Péptido Intestinal Vasoactivo/efectos de los fármacos , Receptores de Tipo II del Péptido Intestinal Vasoactivo/metabolismo , Vasoconstrictores/farmacologíaRESUMEN
The pathogenesis of inflammatory bowel syndrome (IBD), which includes Crohn's disease (CD) and ulcerative colitis (UC) is poorly understood. However, an inflammatory component is a common hallmark. It has been suggested that CD principally involves Th1 and/or Th17 cells, while UC is considered to be more Th2 driven. Because vasoactive intestinal peptide (VIP) has emerged in the last decade as a putative candidate for the treatment of inflammatory diseases with a Th1 component, it may as well serve as a therapeutic target in CD. In addition, experiments using mice deficient in VIP or its receptors have revealed that the endogenously-produced VIP may participate in the regulation of immunity. The aim of the present review is to summarize the quite considerable array of data which suggests that the VIP-receptor system plays a key role in modulating multiple molecular and cellular players involved in IBD.
Asunto(s)
Enfermedades Inflamatorias del Intestino/fisiopatología , Péptido Intestinal Vasoactivo/fisiología , Animales , Humanos , Enfermedades Inflamatorias del Intestino/tratamiento farmacológico , Enfermedades Inflamatorias del Intestino/metabolismo , Ratones , Ratones Noqueados , Receptores de Péptido Intestinal Vasoactivo/biosíntesis , Receptores de Péptido Intestinal Vasoactivo/fisiología , Receptores Toll-Like/efectos de los fármacos , Péptido Intestinal Vasoactivo/genética , Péptido Intestinal Vasoactivo/uso terapéuticoAsunto(s)
Encéfalo/fisiología , Fármacos Neuroprotectores , Polipéptido Hipofisario Activador de la Adenilato-Ciclasa/fisiología , Péptido Intestinal Vasoactivo/fisiología , Animales , Encéfalo/efectos de los fármacos , Encéfalo/metabolismo , Humanos , Fármacos Neuroprotectores/farmacología , Polipéptido Hipofisario Activador de la Adenilato-Ciclasa/farmacología , Receptores del Polipéptido Activador de la Adenilato-Ciclasa Hipofisaria/metabolismo , Receptores del Polipéptido Activador de la Adenilato-Ciclasa Hipofisaria/fisiología , Receptores de Péptido Intestinal Vasoactivo/metabolismo , Receptores de Péptido Intestinal Vasoactivo/fisiología , Péptido Intestinal Vasoactivo/farmacologíaRESUMEN
Vasoactive intestinal peptide (VIP) is a basic 28 amino acid peptide that binds to a member of the class II family of G protein-coupled receptors (GPCRs). It is widely expressed throughout the body and plays an important role in numerous biological functions. VIP acts via three different GPCRs: VPAC1, VPAC2, and PAC1, which have been identified in various tissues, including brain, lung, kidney, gastrointestinal tract, tongue, and also on immunocompetent cells such as macrophages and lymphocytes. There is mounting evidence that VIP expression and signaling is altered in numerous neurological disorders, and it is becoming apparent that VIP and its receptors could be therapeutic loci for the treatment of several pathological conditions of the central nervous system. In this review, we describe the pathology of several major neurological disorders and discuss the potential pharmacotherapeutic role of VIP and its receptors for the treatment of disorders such as Alzheimer's disease, Parkinson's disease, and Autism Spectrum Disorders.
Asunto(s)
Enfermedades del Sistema Nervioso/tratamiento farmacológico , Receptores de Péptido Intestinal Vasoactivo/efectos de los fármacos , Péptido Intestinal Vasoactivo/uso terapéutico , Animales , Sistemas de Liberación de Medicamentos/métodos , Humanos , Modelos Biológicos , Enfermedades del Sistema Nervioso/metabolismo , Enfermedades del Sistema Nervioso/fisiopatología , Receptores de Péptido Intestinal Vasoactivo/metabolismo , Receptores de Péptido Intestinal Vasoactivo/fisiología , Péptido Intestinal Vasoactivo/metabolismo , Péptido Intestinal Vasoactivo/fisiologíaRESUMEN
Evidence suggests that circadian rhythms are regulated through diffusible signals generated by the suprachiasmatic nucleus (SCN). Vasoactive intestinal peptide (VIP) is located in SCN neurons positioned to receive photic input from the retinohypothalamic tract and transmit information to other SCN cells and adjacent hypothalamic areas. Studies using knockout mice indicate that VIP is essential for synchrony among SCN cells and for the expression of normal circadian rhythms. To test the hypothesis that VIP is also an SCN output signal, we recorded wheel-running activity rhythms in hamsters and continuously infused the VIP receptor agonist BAY 55-9837 in the third ventricle for 28 days. Unlike other candidate output signals, infusion of BAY 55-9837 did not affect activity levels. Instead, BAY 55-9837 lengthened the circadian period by 0.69 +/- 0.04 h (P < 0.0002 compared with controls). Period returned to baseline after infusions. We analyzed the effect of BAY 55-9837 on cultured SCN from PER2::LUC mice to determine if lengthening of the period by BAY 55-9837 is a direct effect on the SCN. Application of 10 muM BAY 55-9837 to SCN in culture lengthened the period of PER2 luciferase expression (24.73 +/- 0.24 h) compared with control SCN (23.57 +/- 0.26, P = 0.01). In addition, rhythm amplitude was significantly increased, consistent with increased synchronization of SCN neurons. The effect of BAY 55-9837 in vivo on period is similar to the effect of constant light. The present results suggest that VIP-VPAC2 signaling in the SCN may play two roles, synchronizing SCN neurons and setting the period of the SCN as a whole.
Asunto(s)
Ritmo Circadiano/fisiología , Receptores de Péptido Intestinal Vasoactivo/metabolismo , Péptido Intestinal Vasoactivo/metabolismo , Animales , Ritmo Circadiano/efectos de los fármacos , Cricetinae , Hipotálamo/metabolismo , Luz , Masculino , Mesocricetus , Ratones , Ratones Noqueados/metabolismo , Actividad Motora , Neuronas/efectos de los fármacos , Neuronas/metabolismo , Neuronas/fisiología , Fragmentos de Péptidos , Receptores de Péptido Intestinal Vasoactivo/fisiología , Transducción de Señal/fisiología , Núcleo Supraquiasmático/metabolismo , Núcleo Supraquiasmático/fisiología , Péptido Intestinal Vasoactivo/farmacologíaRESUMEN
The evolution, function and interaction of ligand-receptor pairs are of major pharmaceutical interest. Comparative sequence analysis approaches using data from phylogenetically distant organisms can provide insights into their origin and possible physiological roles. The present review focuses on the pituitary adenylate cyclase-activating polypeptide (PACAP), vasoactive intestinal polypeptide (VIP) and their receptors in the metazoa. A PACAP-like peptide is present in tunicates and chordates while VIP- and PACAP/VIP-specific receptors have only been isolated in the latter phyla. The apparently disparate evolution of the ligands and their specific receptors raises questions about their evolution during the metazoan radiation and also about how the ligands may have acquired new functions.
Asunto(s)
Polipéptido Hipofisario Activador de la Adenilato-Ciclasa/genética , Receptores del Polipéptido Activador de la Adenilato-Ciclasa Hipofisaria/genética , Receptores de Péptido Intestinal Vasoactivo/genética , Péptido Intestinal Vasoactivo/genética , Secuencia de Aminoácidos , Animales , Evolución Molecular , Ligandos , Datos de Secuencia Molecular , Polipéptido Hipofisario Activador de la Adenilato-Ciclasa/metabolismo , Polipéptido Hipofisario Activador de la Adenilato-Ciclasa/fisiología , Receptores del Polipéptido Activador de la Adenilato-Ciclasa Hipofisaria/metabolismo , Receptores del Polipéptido Activador de la Adenilato-Ciclasa Hipofisaria/fisiología , Receptores de Péptido Intestinal Vasoactivo/metabolismo , Receptores de Péptido Intestinal Vasoactivo/fisiología , Homología de Secuencia de Aminoácido , Péptido Intestinal Vasoactivo/metabolismo , Péptido Intestinal Vasoactivo/fisiologíaRESUMEN
Neuroblastoma (NB), the most common extracranial tumor during childhood arises from the embryonic sympathetic nervous system. Remarkably, NB can spontaneously regress, even after metastasis, leading to complete remission. Subpopulations of neuroblastic (N-type) and nonneuronal cells coexist in NB. Expression of the high-affinity nerve growth factor (NGF) TrkA receptor in NB is correlated with good prognosis, while MYCN amplification is associated with advanced stages of disease. N-type cells undergo differentiation when treated with different compounds, such as retinoids, phorbol esters, growth and neurotrophic NGF and neuropeptides, especially vasoactive intestinal peptide (VIP). These substances stabilize proliferation, leading to a more mature neuronal phenotype, neurite outgrowth and induction of expression of sympathetic neuronal markers. Therefore, receptors for these substances and their associated signalling pathways, appear like promising targets for the development of novel NB therapeutics. The aim of the present review is to summarize the quite considerable array of data, concerning production of VIP and related peptides, expression of their receptors in NB and the key regulation exerted by the VIP-receptor system in the control of NB cell behaviour.
Asunto(s)
Neuroblastoma/fisiopatología , Receptores de Péptido Intestinal Vasoactivo/fisiología , Animales , Diferenciación Celular , Humanos , Neuroblastoma/patología , Receptores de Péptido Intestinal Vasoactivo/agonistas , Transducción de SeñalRESUMEN
The role of vasoactive intestinal polypeptide (VIP) receptors on excitable properties of neurones in slices acutely prepared from the suprachiasmatic nuclei (SCN) of wild-type (WT) and VPAC(2)-receptor-deficient (Vipr2 ( -/- )) mice was studied under voltage clamp with the use of patch-clamp recording in the whole-cell configuration. The resting membrane potential in Vipr2 ( -/- ) neurones was significantly hyperpolarised as compared to WT cells (-60+/-7 vs -72+/-6 mV, p<0.01). Bath application of 100 nM VIP or the VPAC(2) receptor agonist RO 25-1553 triggered a slow inward current in a subpopulation of WT SCN neurones; the VIP-induced current was not affected by slice incubation with 25 microM of bicuculline but disappeared completely when the cells were dialysed with CsCl-containing/K(+)-free solution. Application of VIP or RO 25-1553 to neurones from Vipr2 ( -/- ) mice did not induce currents in all cells tested. Incubation of WT slices with 100 nM VIP or RO 25-1553 resulted in inhibition of fast tetrodotoxin-sensitive sodium currents and delayed rectifier K(+) currents in most of the cells tested. This effect was completely absent in cells from Vipr2 ( -/- ) mice. We postulate that VIP receptors control excitability of SCN neurones at the postsynaptic level by direct modulation of membrane potential via inhibition of K(+) channels and by tonic inhibition of sodium and potassium voltage-gated currents.
Asunto(s)
Potenciales Postsinápticos Excitadores/fisiología , Neuronas/fisiología , Receptores de Péptido Intestinal Vasoactivo/fisiología , Núcleo Supraquiasmático/fisiología , Animales , Ratones , Ratones Noqueados , Neuronas/metabolismo , Potasio/metabolismo , Canales de Potasio/metabolismo , Sodio/metabolismoRESUMEN
When exposed to vasoactive intestinal peptide (VIP), the human wild type VPAC1 receptor expressed in Chinese hamster ovary (CHO) cells is rapidly phosphorylated, desensitized, and internalized in the endosomal compartment and is not re-expressed at the cell membrane within 2 h after agonist removal. The aims of the present work were first to correlate receptor phosphorylation level to internalization and recycling, measured by flow cytometry and in some cases by confocal microscopy using a monoclonal antibody that did not interfere with ligand binding, and second to identify the phosphorylated Ser/Thr residues. Combining receptor mutations and truncations allowed identification of Ser250 (in the second intracellular loop), Thr429, Ser435, Ser448 or Ser449, and Ser455 (all in the distal part of the C terminus) as candidates for VIP-stimulated phosphorylation. The effects of single mutations were not additive, suggesting alternative phosphorylation sites in mutated receptors. Replacement of all of the Ser/Thr residues in the carboxyl-terminal tail and truncation of the domain containing these residues completely inhibited VIP-stimulated phosphorylation and receptor internalization. There was, however, no direct correlation between receptor phosphorylation and internalization; in some truncated and mutated receptors, a 70% reduction in phosphorylation had little effect on internalization. In contrast to results obtained on the wild type and all of the mutated or truncated receptors that still underwent phosphorylation, internalization of the severely truncated receptor was reversed within 2 h of incubation in the absence of the agonist. Receptor recovery was blocked by monensin, an endosome inhibitor.
Asunto(s)
Receptores de Péptido Intestinal Vasoactivo/química , Receptores de Péptido Intestinal Vasoactivo/fisiología , Adenilil Ciclasas/metabolismo , Secuencia de Aminoácidos , Animales , Anticuerpos Monoclonales/química , Western Blotting , Células CHO , Línea Celular , Membrana Celular/metabolismo , Cricetinae , AMP Cíclico/química , Endosomas/metabolismo , Citometría de Flujo , Humanos , Inmunoprecipitación , Ligandos , Microscopía Confocal , Datos de Secuencia Molecular , Monensina/química , Mutación , Péptidos/química , Fosforilación , Mutación Puntual , Unión Proteica , Estructura Terciaria de Proteína , Transporte de Proteínas , Receptores de Péptido Intestinal Vasoactivo/metabolismo , Receptores de Tipo I del Polipéptido Intestinal Vasoactivo , Serina/química , Factores de Tiempo , Péptido Intestinal Vasoactivo/químicaRESUMEN
To understand the role of growth hormone-releasing hormone (GHRH) and pituitary adenylate cyclase-activating polypeptide (PACAP) and to examine the functional significance of the co-expression of GHRH and PACAP in fish, their receptors were characterized in zebrafish. Three cDNAs encoding the PAC(1) receptor, the VPAC(1) receptor, and the partial GHRH receptor were identified from zebrafish. Functional expression of the PAC(1) and VPAC(1) receptors revealed that both are potently coupled to the adenylyl cyclase pathway, but only the PAC(1) receptor is coupled to the phospholipase C pathway. Transcripts for all three receptors were widely distributed, often in an overlapping pattern in the adult zebrafish. Also, one splice variant of the partial GHRH receptor and three splice variants of the PAC(1) receptor were identified from adult zebrafish. The long GHRH receptor transcript contained a 27 amino acid insert in transmembrane domain 5 encoding a premature stop codon leading to a truncated receptor protein. For the PAC(1) receptor, two of the splice variants corresponded to the hop1 and hop2 variants characterized in mammals. The third splice variant identified from the gill encoded a novel 107 bp insert containing a premature stop codon. Therefore, PACAP and GHRH have widespread, overlapping target sites suggesting a coordinated role for these hormones in evolution.
Asunto(s)
Hormona Liberadora de Hormona del Crecimiento/genética , Receptores de Superficie Celular/genética , Receptores de Péptido Intestinal Vasoactivo/genética , Adenilil Ciclasas/metabolismo , Animales , Secuencia de Bases , Codón sin Sentido , ADN Complementario , Hormona Liberadora de Hormona del Crecimiento/fisiología , Datos de Secuencia Molecular , Empalme del ARN , ARN Mensajero/análisis , Receptores de Superficie Celular/fisiología , Receptores del Polipéptido Activador de la Adenilato-Ciclasa Hipofisaria , Receptores del Polipéptido Activador de la Adenilato-Ciclasa Hipofisaria , Receptores de Péptido Intestinal Vasoactivo/fisiología , Receptores de Tipo I del Polipéptido Intestinal Vasoactivo , Alineación de Secuencia , Distribución Tisular , Fosfolipasas de Tipo C/metabolismo , Pez CebraRESUMEN
Neuropeptides are expressed in neurons innervating endocrine cells or in endocrine cells and cancer cells, and are released on site to act as hormones and growth factors. Vasoactive intestinal peptide (VIP) was first discovered in the early 1970s and has since become the area of research for many laboratories. VIP has a neuroendocrine role as it is intimately involved with the synthesis, secretion and action of other neuroendocrine hormones as well as cytokines and chemokines. Major outcomes of VIP downregulation encompass developmental and behavioral dysfunctions, including impaired diurnal rhythms. Overexpression of VIP has been associated with diarrhea and cancer, and overexpression of VIP receptors is associated with cancerous growth. This short review outlines some of the recent progress made in VIP research.
Asunto(s)
Fármacos Gastrointestinales/uso terapéutico , Péptido Intestinal Vasoactivo/uso terapéutico , Animales , Antiinflamatorios , Sistema Cardiovascular/efectos de los fármacos , Diabetes Mellitus/tratamiento farmacológico , Humanos , Fármacos Neuroprotectores/farmacología , Receptores de Péptido Intestinal Vasoactivo/fisiología , Transducción de Señal/fisiología , Péptido Intestinal Vasoactivo/sangre , Péptido Intestinal Vasoactivo/farmacologíaRESUMEN
Gastrointestinal (GI) smooth muscle cell activity is controlled by contractile cholinergic neurons and relaxant non-adrenergic non-cholinergic (NANC) neurons in the myenteric plexus between the circular and longitudinal muscle layer. Decreased or increased NANC relaxation might be involved in the pathophysiology of functional GI motility disorders. Vasoactive intestinal polypeptide (VIP) and nitric oxide (NO) are the primary inhibitory NANC neurotransmitters. As classic neurotransmitters, VIP is stored in vesicles in the nerve endings, while NO is synthetized on demand by the neuronal isoform of NO synthase (nNOS). The VIP/nNOS co-localization in myenteric neurons, reported for various regions of the GI tract in different species, suggests that VIP and NO are co-transmitters. At the presynaptic level, VIP and NO can induce each others release. Most clear-cut evidence for this mechanism was obtained in isolated myenteric ganglia where VIP induced NO release, and NO facilitated VIP release. At the postsynaptic level, many studies support that VIP and NO are parallel co-transmitters, acting via the adenylate cyclase/3'5' adenosine cyclic monophosphate (cAMP) and guanylate cyclase/3'5' cyclic guanosine monophosphate pathway respectively. Mainly based on results obtained in isolated GI smooth muscle cells, a serial postsynaptic VIP/NO interaction model was proposed, whereby VIP is the principle neurotransmitter, acting partially via a VPAC receptor and the adenylate cyclase/cAMP pathway but also by induction of muscular NO production. Recent results suggest that the capacity of VIP to release NO from isolated smooth muscle cells is related to the induction of inducible NOS (iNOS) in the cells during the isolation procedure. The relative contribution of NO and VIP to GI NANC relaxation differs upon tissue and nerve firing frequency, so that interference with either of them will lead to varying effects.
Asunto(s)
Tracto Gastrointestinal/fisiología , Relajación Muscular/fisiología , Músculo Liso/fisiología , Óxido Nítrico/fisiología , Péptido Intestinal Vasoactivo/farmacología , Animales , Interacciones Farmacológicas , Tracto Gastrointestinal/citología , Tracto Gastrointestinal/inervación , Humanos , Relajación Muscular/efectos de los fármacos , Músculo Liso/citología , Músculo Liso/efectos de los fármacos , Vías Nerviosas/anatomía & histología , Vías Nerviosas/química , Vías Nerviosas/fisiología , Neuronas/química , Neuronas/fisiología , Receptores de Péptido Intestinal Vasoactivo/efectos de los fármacos , Receptores de Péptido Intestinal Vasoactivo/fisiologíaRESUMEN
First identified by Said and Mutt some 30 years ago, the vasoactive intestinal peptide (VIP) was originally isolated as a vasodilator peptide. Subsequently, its biochemistry was elucidated, and within the 1st decade, their signature features as a neuropeptide became consolidated. It did not take long for these insights to permeate the field of immunology, out of which surprising new attributes for VIP were found in the last years. VIP is rapidly transforming into something more than a mere hormone. In evolving scientifically from a hormone to a novel agent for modifying immune function and possibly a cytokine-like molecule, VIP research has engaged many physiologists, molecular biologists, biochemists, endocrinologists, and pharmacologists and it is a paradigm to explore mutual interactions between neural and neuroendocrine links in health and disease. The aim of this review is firstly to update our knowledge of the cellular and molecular events relevant to VIP function on the immune system and secondly to gather together recent data that support its role as a type 2 cytokine. Recognition of the central functions VIP plays in cellular processes is focusing our attention on this "very important peptide" as exciting new candidates for therapeutic intervention and drug development.
Asunto(s)
Adyuvantes Inmunológicos/metabolismo , Sistema Inmunológico/fisiología , Péptido Intestinal Vasoactivo/inmunología , Adaptación Fisiológica , Animales , Citocinas/inmunología , Humanos , Inmunidad Innata/fisiología , Receptores de Péptido Intestinal Vasoactivo/metabolismo , Receptores de Péptido Intestinal Vasoactivo/fisiología , Péptido Intestinal Vasoactivo/metabolismoRESUMEN
Vasoactive intestinal peptide and its G protein-coupled receptors, VPAC(1) and VPAC(2), regulate critical aspects of innate and adaptive immunity. T cell VPAC(2)Rs mediate changes in cytokine generation, which potently increase the Th2/Th1 ratio and consequently shift the effector responses toward allergy and inflammation. To examine mechanisms of VPAC(2) promotion of the Th2 phenotype, we analyzed controls of IL-4 transcription in CD4 T cells from T cell-targeted VPAC(2) transgenic (Tg), VPAC(2) knockout, and wild-type (WT) mice. c-maf and junB mRNA, protein, and activity were significantly up-regulated to a higher level in TCR-stimulated CD4 T cells from Tg mice compared with those from knockout and WT C57BL/6 mice. In contrast, GATA3, T-bet, and NFATc levels were identical in WT and Tg CD4 T cells. Vasoactive intestinal peptide binding to VPAC(2) on CD4 T cells specifically induces an up-regulation of the Th2-type transcription factors c-Maf and JunB, which consequently enhances IL-4 and IL-5 production, leading to a Th2-type phenotype.
Asunto(s)
Proteínas de Unión al ADN/fisiología , Proteínas Proto-Oncogénicas c-jun/fisiología , Proteínas Proto-Oncogénicas/fisiología , Receptores de Péptido Intestinal Vasoactivo/fisiología , Células Th2/citología , Péptido Intestinal Vasoactivo/farmacología , Animales , Diferenciación Celular , Proteínas de Unión al ADN/biosíntesis , Humanos , Interleucina-4/biosíntesis , Interleucina-5/biosíntesis , Ratones , Ratones Transgénicos , Unión Proteica , Proteínas Proto-Oncogénicas/biosíntesis , Proteínas Proto-Oncogénicas c-jun/biosíntesis , Proteínas Proto-Oncogénicas c-maf , Receptores de Péptido Intestinal Vasoactivo/genética , Receptores de Péptido Intestinal Vasoactivo/metabolismo , Receptores de Tipo II del Péptido Intestinal Vasoactivo , Regulación hacia Arriba , Péptido Intestinal Vasoactivo/metabolismoRESUMEN
VIP acting via the VPAC(2) receptor is implicated as a key signaling pathway in the maintenance and resetting of the hypothalamic suprachiasmatic nuclei (SCN) circadian pacemaker; circadian rhythms in SCN clock gene expression and wheel-running behavior are abolished in mice lacking the VPAC(2) receptor (Vipr2(-/-)). Here, using immunohistochemical detection of pERK (phosphorylated extracellular signal-regulated kinases 1/2) and c-FOS, we tested whether the gating of photic input to the SCN is maintained in these apparently arrhythmic Vipr2(-/-) mice. Under light/dark and constant darkness, spontaneous expression of pERK and c-FOS in the wild-type mouse SCN was significantly elevated during subjective day compared with subjective night; no diurnal or circadian variation in pERK or c-FOS was detected in the SCN of Vipr2(-/-) mice. In constant darkness, light pulses given during the subjective night but not the subjective day significantly increased expression of pERK and c-FOS in the wild-type SCN. In contrast, light pulses given during both subjective day and subjective night robustly increased expression of pERK and c-FOS in the Vipr2(-/-) mouse SCN. Although photic stimuli activate intracellular pathways within the SCN of Vipr2(-/-) mice, they do not engage the core clock mechanisms. The absence of photic gating, together with the general lack of overt rhythms in circadian output, strongly suggests that the SCN circadian pacemaker is completely dysfunctional in the Vipr2(-/-) mouse.
Asunto(s)
Relojes Biológicos/fisiología , Ritmo Circadiano/fisiología , Receptores de Péptido Intestinal Vasoactivo/fisiología , Núcleo Supraquiasmático/fisiología , Animales , Conducta Animal/fisiología , Relojes Biológicos/genética , Ritmo Circadiano/genética , Oscuridad , Femenino , Masculino , Ratones , Ratones Endogámicos C57BL , Ratones Noqueados , Proteína Quinasa 1 Activada por Mitógenos/metabolismo , Proteína Quinasa 3 Activada por Mitógenos , Proteínas Quinasas Activadas por Mitógenos/metabolismo , Actividad Motora/genética , Actividad Motora/fisiología , Estimulación Luminosa/métodos , Fotoperiodo , Proteínas Proto-Oncogénicas c-fos/metabolismo , Receptores de Péptido Intestinal Vasoactivo/genética , Receptores de Tipo II del Péptido Intestinal Vasoactivo , Transducción de Señal/genética , Transducción de Señal/fisiologíaRESUMEN
1. The mechanisms and receptors involved in the vasoactive intestinal peptide (VIP)- and pituitary adenylate cyclase-activating polypeptide (PACAP)-induced relaxations of the pig intravesical ureter were investigated. 2. VIP, PACAP 38 and PACAP 27 concentration-dependently relaxed U46619-contracted ureteral strips with a similar potency. [Ala(11,22,28)]-VIP, a VPAC(1) agonist, showed inconsistent relaxations. 3. The neuronal voltage-gated Ca(2+) channel inhibitor, omega-conotoxin GVIA (omega-CgTX, 1 microm), reduced the VIP relaxations. Urothelium removal or blockade of capsaicin-sensitive primary afferents, nitric oxide (NO) synthase and guanylate cyclase with capsaicin (10 microm), N(G)-nitro-l-arginine (l-NOARG, 100 microm) and 1H-[1,2,4]-oxadiazolo[4,3-a]quinoxalin-1-one (ODQ, 5 microm), respectively, did not change the VIP relaxations. However, the PACAP 38 relaxations were reduced by omega-CgTX, capsaicin, l-NOARG and ODQ. 4. The VIP and VIP/PACAP receptor antagonists, [Lys(1), Pro(2,5), Arg(3,4), Tyr(6)]-VIP (1 microm) and PACAP (6-38) (0.4 microm), inhibited VIP and VIP and PACAP 38, respectively, relaxations. 5. The nonselective and large-conductance Ca(2)-activated K(+) channel blockers, tetraethylammonium (3 mm) and charybdotoxin (0.1 microm), respectively, and neuropeptide Y (0.1 microm) did not modify the VIP relaxations. The small-conductance Ca(2)-activated K(+) channel blocker apamin (1 microm) did not change the PACAP 27 relaxations. 6. The cAMP-dependent protein kinase A (PKA) blocker, 8-(4-chlorophenylthio)adenosine-3',5'-cyclic monophosphorothioate (Rp-8-CPT-cAMPS, 100 microm), reduced VIP relaxations. The phosphodiesterase 4 inhibitor rolipram and the adenylate cyclase activator forskolin relaxed ureteral preparations. The rolipram relaxations were reduced by Rp-8-CPT-cAMPS. Forskolin (30 nm) evoked a potentiation of VIP relaxations. 7. These results suggest that VIP and PACAP relax the pig ureter through smooth muscle receptors, probably of the VPAC(2) subtype, linked to a cAMP-PKA pathway. Neuronal VPAC receptors localized at motor nerves and PAC(1) receptors placed at sensory nerves and coupled to NO release, seem also to be involved in the VIP and PACAP 38 relaxations.
Asunto(s)
AMP Cíclico/análogos & derivados , Neuropéptidos/farmacología , Fragmentos de Péptidos/farmacología , Receptores de Péptido Intestinal Vasoactivo/fisiología , Células Receptoras Sensoriales/fisiología , Uréter/efectos de los fármacos , Péptido Intestinal Vasoactivo/farmacología , Ácido 15-Hidroxi-11 alfa,9 alfa-(epoximetano)prosta-5,13-dienoico/farmacología , Animales , Apamina/farmacología , Capsaicina/farmacología , Caribdotoxina/administración & dosificación , Colforsina/farmacología , AMP Cíclico/farmacología , Relación Dosis-Respuesta a Droga , Sinergismo Farmacológico , Femenino , Guanilato Ciclasa/farmacología , Masculino , Músculo Liso/efectos de los fármacos , Músculo Liso/fisiología , NG-Nitroarginina Metil Éster/farmacología , Neuronas Aferentes/efectos de los fármacos , Neuronas Aferentes/fisiología , Neuropéptido Y/fisiología , Neuropéptidos/antagonistas & inhibidores , Óxido Nítrico Sintasa/farmacología , Oxadiazoles/farmacología , Fragmentos de Péptidos/antagonistas & inhibidores , Polipéptido Hipofisario Activador de la Adenilato-Ciclasa , Canales de Potasio Calcio-Activados/fisiología , Quinoxalinas/farmacología , Receptores de Péptido Relacionado con el Gen de Calcitonina , Receptores de Péptidos/antagonistas & inhibidores , Receptores de Péptidos/efectos de los fármacos , Rolipram/antagonistas & inhibidores , Rolipram/farmacología , Porcinos , Tetraetilamonio/administración & dosificación , Uréter/citología , Uréter/lesiones , Péptido Intestinal Vasoactivo/antagonistas & inhibidores , omega-Conotoxina GVIA/farmacologíaRESUMEN
A transient increase in skin blood flow in response to an innocuous local pressure application, defined as pressure-induced vasodilatation (PIV), delays the occurrence of ischaemia, suggesting a protective feature against applied pressure. The PIV response depends on capsaicin-sensitive nerve fibres and calcitonin gene-related peptide (CGRP) has been shown to be involved. In these fibres, CGRP coexists with pituitary adenylate cyclase-activating polypeptide (PACAP). Three distinct receptors mediate the biological effects of PACAP: VPAC1 and VPAC2 receptors binding with the same affinity for PACAP and vasoactive intestinal peptide and PAC1 receptors showing high selectivity for PACAP. Because the receptors are widely expressed in the nervous system and in the skin, we hypothesized that at least one of them is involved in PIV development. To verify this hypothesis, we used [D-p-Cl-Phe(6),Leu(17)]-VIP (nonspecific antagonist of VPAC1/VPAC2 receptors), PG 97-269 (antagonist of VPAC1 receptors), PACAP(6-38) (antagonist of VPAC2/PAC1 receptors) and Max.d.4 (antagonist of PAC1 receptors) in anaesthetized rodents. The blockade of VPAC1/VPAC2, VPAC1 or VPAC2/PAC1 receptors eliminated the PIV response, whereas PAC1 blockade had no effect, demonstrating an involvement of VPAC1/VPAC2 receptors in PIV development. Moreover, endothelium-independent and -dependent vasodilator responses were unchanged by the VPAC1/VPAC2 antagonist. Thus, the absence of a PIV response following VPAC1/VPAC2 blockade cannot be explained by any dysfunction of the vascular smooth muscle or endothelial vasodilator capacity. The involvement of VPAC1/VPAC2 receptors in the development of PIV seems to imply a series relationship in which each receptor type (CGRP, VPAC1, VPAC2) is necessary for the full transmission of the response.