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Figueira L, Israel A. Cerebellar Adrenomedullinergic System. Role in Cardiovascular Regulation. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2016; 956:541-560. [PMID: 27614623 DOI: 10.1007/5584_2016_48] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Adrenomedullin (AM) is a multifunctional peptide which exerts numerous biological activities through the activation of AM1 (CRLR + RAMP2) and AM2 (CRLR + RAMP3) receptors. AM immunoreactivity, AM binding sites and CRLR, RAMP1, RAMP2 and RAMP3 are expressed in rat cerebellar vermis. AM binding sites are discretely and differentially distributed in the rat cerebellar cortex with higher levels detected in SHR when compared with WKY rats. In addition, there is an up-regulation of cerebellar CGRP1 (CRLR + RAMP1) and AM2 (CRLR + RAMP3) receptors and a down-regulation of AM1 (CRLR + RAMP2) receptor during hypertension associated with a decreased AM expression. These changes may constitute a mechanism which contributes to the development of hypertension, and supports the notion that cerebellar AM is involved in the regulation of blood pressure. Cerebellar AM activates ERK, increases cAMP, cGMP and nitric oxide, and decreases antioxidant enzyme activity. These effects are mediated through AM1 receptor since they are blunted by AM(22-52). AM-stimulated cAMP production is mediated through AM2 and CGRP receptors. In vivo administration of AM into the cerebellar vermis caused a profound, specific and dose-dependent hypotensive effect in SHR, but not in normotensive WKY rats. This effect was mediated through AM1 receptor since it was abolished by AM(22-52). In addition, AM injected into the cerebellar vermis reduced vasopressor response to footshock stress. These findings demonstrate dysregulation of cerebellar AM system during hypertension, and suggest that cerebellar AM plays an important role in the regulation of blood pressure. Likewise, they constitute a novel mechanism of blood pressure control which has not been described so far.
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Affiliation(s)
- Leticia Figueira
- Laboratory of Neuropeptides, School of Pharmacy, Universidad Central de Venezuela, Caracas, Venezuela.,School of Bioanalysis, Department of Health Sciences, Universidad de Carabobo, Carabobo, Venezuela
| | - Anita Israel
- Laboratory of Neuropeptides, School of Pharmacy, Universidad Central de Venezuela, Caracas, Venezuela.
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Renaud B, Schuetz P, Claessens YE, Labarère J, Albrich W, Mueller B. Proadrenomedullin improves Risk of Early Admission to ICU score for predicting early severe community-acquired pneumonia. Chest 2013; 142:1447-1454. [PMID: 22661450 DOI: 10.1378/chest.11-2574] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
BACKGROUND Whether proadrenomedullin (ProADM) improves the performance of the Risk of Early Admission to ICU (REA-ICU) score in predicting early, severe community-acquired pneumonia (ESCAP) has not been demonstrated. METHODS Secondary analysis was completed of the original data from 877 consecutive patients with community-acquired pneumonia (CAP) enrolled in the Procalcitonin-Guided Antibiotic Therapy and Hospitalization in Patients With Lower Respiratory Tract Infections (ProHOSP) study, a multicenter trial in EDs of six tertiary-care hospitals in Switzerland. ESCAP was defined by either the requirement for mechanical ventilation or vasopressive drugs or occurrence of death within 3 days of ED presentation. RESULTS Eighty patients (9.1%) developed ESCAP (47 required mechanical ventilation, 19 vasopressive drugs, and 16 died) within 3 days of ED presentation. They had a higher median ProADM value (2.18 nmol/L vs 1.15 nmol/L, P < .001). Combining ProADM testing with the REA-ICU score improved the area under the curve (0.81) compared with either parameter (ProADM [0.73] or REA-ICU score [0.76], P < .001) and resulted in a net reclassification improvement of 0.20 (P < .001). A ProADM value ≥ 1.8 nmol/L or assignment to REA-ICU risk classes III-IV predicted ESCAP with a sensitivity of 76.3% and a negative predictive value of 96.7%. Excluding 21 patients with major criteria of severe CAP on presentation showed similar results. CONCLUSION These study findings demonstrate that the addition of ProADM to the REA-ICU score improves the classification of a substantial proportion of patients in the ED at intermediate or high risk for ESCAP, which may translate into better triage decisions.
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Affiliation(s)
- Bertrand Renaud
- Service d'urgence, Assistance Publique des Hôpitaux de Paris, Groupe Hospitalier Henri Mondor-Albert Chenevier, Créteil, France; Université Paris Est Créteil, Faculté de Médecine, Créteil, France.
| | | | | | - José Labarère
- Techniques de l'Ingénierie Médicale et de la Complexité, Unité Mixte de Recherche 5525 Centre National de Recherche Scientifique Université Joseph Fourier-Grenoble 1, Grenoble, France
| | - Werner Albrich
- Medical University Clinic, Kantonsspital Aarau, Switzerland
| | - Beat Mueller
- Medical University Clinic, Kantonsspital Aarau, Switzerland
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Yen DHT, Chen LC, Shen YC, Chiu YC, Ho IC, Lou YJ, Chen IC, Yen JC. Protein kinase A-dependent neuronal nitric oxide synthase activation mediates the enhancement of baroreflex response by adrenomedullin in the nucleus tractus solitarii of rats. J Biomed Sci 2011; 18:32. [PMID: 21595896 PMCID: PMC3115842 DOI: 10.1186/1423-0127-18-32] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2011] [Accepted: 05/19/2011] [Indexed: 11/10/2022] Open
Abstract
Background Adrenomedullin (ADM) exerts its biological functions through the receptor-mediated enzymatic mechanisms that involve protein kinase A (PKA), or neuronal nitric oxide synthase (nNOS). We previously demonstrated that the receptor-mediated cAMP/PKA pathway involves in ADM-enhanced baroreceptor reflex (BRR) response. It remains unclear whether ADM may enhance BRR response via activation of nNOS-dependent mechanism in the nucleus tractus solitarii (NTS). Methods Intravenous injection of phenylephrine was administered to evoke the BRR before and at 10, 30, and 60 min after microinjection of the test agents into NTS of Sprague-Dawley rats. Western blotting analysis was used to measure the level and phosphorylation of proteins that involved in BRR-enhancing effects of ADM (0.2 pmol) in NTS. The colocalization of PKA and nNOS was examined by immunohistochemical staining and observed with a laser confocal microscope. Results We found that ADM-induced enhancement of BRR response was blunted by microinjection of NPLA or Rp-8-Br-cGMP, a selective inhibitor of nNOS or protein kinase G (PKG) respectively, into NTS. Western blot analysis further revealed that ADM induced an increase in the protein level of PKG-I which could be attenuated by co-microinjection with the ADM receptor antagonist ADM22-52 or NPLA. Moreover, we observed an increase in phosphorylation at Ser1416 of nNOS at 10, 30, and 60 min after intra-NTS administration of ADM. As such, nNOS/PKG signaling may also account for the enhancing effect of ADM on BRR response. Interestingly, biochemical evidence further showed that ADM-induced increase of nNOS phosphorylation was prevented by co-microinjection with Rp-8-Br-cAMP, a PKA inhibitor. The possibility of PKA-dependent nNOS activation was substantiated by immunohistochemical demonstration of co-localization of PKA and nNOS in putative NTS neurons. Conclusions The novel finding of this study is that the signal transduction cascade that underlies the enhancement of BRR response by ADM in NTS is composed sequentially of cAMP/PKA and nNOS/PKG pathways.
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Affiliation(s)
- David H T Yen
- Institute of Emergency and Critical Care Medicine, School of Medicine, National Yang-Ming University, Taipei, Taiwan
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Li L, Tang F, O WS. Coexpression of adrenomedullin and its receptor component proteins in the reproductive system of the rat during gestation. Reprod Biol Endocrinol 2010; 8:130. [PMID: 21034462 PMCID: PMC2984462 DOI: 10.1186/1477-7827-8-130] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/29/2010] [Accepted: 10/29/2010] [Indexed: 11/11/2022] Open
Abstract
BACKGROUND Adrenomedullin (ADM), a novel vasorelaxant peptide, was found in human/rat ovaries and uteri. Plasma ADM level increases in pregnant women and pregnant rats. METHODS The gene expression levels of Adm and its receptor components - Crlr, Ramp1, Ramp2 and Ramp3, the ADM peptide concentration and localization in the rat female reproductive system during gestation were studied by real-time RT-PCR, EIA and immunohistochemical techniques. RESULTS The mRNAs of Adm and its receptor component and ADM were differentially distributed between implantation sites and inter-implantation sites of the pregnant uterus. The day on which vaginal sperm were found was taken to be pregnancy day 1. The Adm mRNA levels in the implantation sites of the uteri in mid- (day 12) and late pregnancy (day 17) were more than 10-fold higher than those in nonpregnancy, pre-implantation (day 3) or early (day 7) pregnancy. ADM was localized in the endometrial stroma with increased immunoreactivity from nonpregnancy to pregnancy. The ADM level and the mRNA levels of Adm, Crlr, Ramp2 and Ramp3 in the corpus luteum all increased in late pregnancy compared with early pregnancy. The gene expression of Adm and it receptor components and intense immunostaining of ADM were also found in the oviduct during pregnancy. CONCLUSIONS The gene expressions levels of Adm and its receptor components - Crlr, Ramp1, Ramp2 and Ramp3, and ADM peptide concentration exhibited a spatio-temporal pattern in the rat female reproductive system during gestation and this suggests that ADM may play important roles in gestation.
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Affiliation(s)
- Lei Li
- Department of Physiology, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Pokfulam, Hong Kong SAR, China
| | - Fai Tang
- Department of Physiology, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Pokfulam, Hong Kong SAR, China
- Centre of Heart, Brain, Hormone and Healthy Aging, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Pokfulam, Hong Kong SAR, China
| | - Wai-Sum O
- Department of Anatomy, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Pokfulam, Hong Kong SAR, China
- Centre of Reproduction, Development and Growth, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Pokfulam, Hong Kong SAR, China
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Pöyhönen-Alho M, Viitasalo M, Nicholls MG, Lindström BM, Väänänen H, Kaaja R. Imbalance of the autonomic nervous system at night in women with gestational diabetes. Diabet Med 2010; 27:988-94. [PMID: 20722671 DOI: 10.1111/j.1464-5491.2010.03062.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
AIMS Autonomic nervous system dysfunction is observed in Type 2 diabetes. As gestational diabetes is a potent risk factor of later Type 2 diabetes, we set out to determine whether autonomic nervous system imbalance could already be observed in women with this condition. Because activity of the sympathetic nervous system tends to be relatively stable in the nocturnal hours, we performed the study at night. RESEARCH DESIGN AND METHODS We studied 41 women with gestational diabetes, 22 healthy pregnant controls and 14 non-pregnant controls. We assayed plasma noradrenaline at 24.00, 04.00 and 07.00 h and performed an overnight Holter recording for heart rate variability analysis. In addition, we assayed plasma adrenomedullin, a cardiovascular protective hormone. RESULTS Compared with non-pregnant controls, plasma noradrenaline levels were increased at 04.00 and 07.00 h in the gestational diabetic (P = 0.003) and pregnant control (P = 0.002) groups, with no difference between them. Heart rate variability, very-low-frequency and low-frequency power were lower in pregnant groups compared to the non-pregnant controls. Heart rate variability remained unchanged between specified sampling times in the gestational diabetic group, in contrast to fluctuation seen in the control groups. CONCLUSIONS Gestational diabetes, compared with normal pregnancy, seems not to be a state of overall sympathetic nervous system activation. At the heart level, however, an inhibitory effect on autonomic nervous system modulation was seen. Plasma noradrenaline and heart rate variability correlated well, supporting the use of this function in future studies of overall sympathetic activity during pregnancy.
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Affiliation(s)
- M Pöyhönen-Alho
- Department of Obstetrics and Gynecology, Helsinki University Central Hospital, Helsinki, Finland
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Ho LK, Chen K, Ho IC, Shen YC, Yen DHT, Li FCH, Lin YC, Kuo WK, Lou YJ, Yen JC. Adrenomedullin enhances baroreceptor reflex response via cAMP/PKA signaling in nucleus tractus solitarii of rats. Neuropharmacology 2008; 55:729-36. [PMID: 18616957 DOI: 10.1016/j.neuropharm.2008.06.024] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2008] [Revised: 06/06/2008] [Accepted: 06/06/2008] [Indexed: 11/16/2022]
Abstract
Adrenomedullin (ADM), a 52-amino acid peptide, elicits differential cardiovascular responses when it is administered systemically or directly to the brain. We evaluated in the present study the hypothesis that ADM may modulate baroreceptor reflex (BRR) response through an ADM receptor-mediated cAMP/ protein kinase A (PKA)-dependent mechanism in the nucleus tractus solitarii (NTS), the terminal site for primary baroreceptor afferents, using Sprague-Dawley rats. Our immunoblot and immunohistochemical results showed that the two component proteins of the ADM(1) receptor complex, calcitonin receptor-like receptor (CRLR) and receptor activity modifying protein (RAMP)-2, were uniformly distributed and highly co-localized in the NTS. Site-specific microinjection of ADM (0.02-0.2pmol) unilaterally into the NTS significantly increased BRR response and sensitivity in a time- and dose-related manner, without affecting arterial pressure and heart rate. The BRR enhancing effect of ADM was also temporally correlated with an up-regulation of PKA(beta), the active form of PKA and an increase in PKA activity. In addition, the ADM-evoked BRR enhancement or PKA activation was abolished by co-microinjection with a selective ADM(1) receptor antagonist, ADM(22-52), an adenylyl cyclase inhibitor, SQ22536, or a PKA inhibitor, Rp-8-bromo-cAMP. These results suggest that ADM enhances BRR via activation of a cAMP/PKA-dependent mechanism by acting site-specifically on ADM(1) receptors in NTS.
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Affiliation(s)
- L K Ho
- Institute of Pharmacology, National Yang-Ming University, Taipei, Taiwan, Republic of China
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Peterson JR, Sharma RV, Davisson RL. Reactive oxygen species in the neuropathogenesis of hypertension. Curr Hypertens Rep 2007; 8:232-41. [PMID: 17147922 DOI: 10.1007/s11906-006-0056-1] [Citation(s) in RCA: 112] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
New evidence that has emerged during the past several years clearly demonstrates that reactive oxygen species (ROS) in the brain play a crucial role in blood pressure regulation by serving as signaling molecules within neurons of cardiovascular control regions. In the forebrain, midbrain, and hindbrain, a key role for oxidant stress in the pathogenesis of angiotensin II-dependent and various other models of neurogenic hypertension has also been uncovered. As in the peripheral vasculature, NAD(P)H oxidase appears to be a major enzymatic source of brain ROS, and various homologues of the catalytic subunit of this enzyme appear to be differentially localized to cardiovascular-regulating nuclei in the brain. Recent studies have begun to elucidate the downstream effects of ROS in neurons, and it is now clear that ROS may interact with a number of well-described intracellular signaling pathways involved in neuronal activation. These exciting new discoveries have furthered our understanding of the pathogenesis of neurogenic hypertension and may ultimately lead to the development of new treatments. In this review, we discuss recent evidence in support of a role for brain ROS in the pathogenesis of hypertension and summarize current studies aimed at uncovering the complex mechanisms by which brain ROS regulate blood pressure in both health and cardiovascular disease.
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Affiliation(s)
- Jeffrey R Peterson
- Anatomy and Cell Biology, 1-251 Bowen Science Building, The Roy J. and Lucille A. Carver College of Medicine, The University of Iowa, Iowa City, IA 52245, USA
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Ren YS, Yang JH, Zhang J, Pan CS, Yang J, Zhao J, Pang YZ, Tang CS, Qi YF. Intermedin 1-53 in central nervous system elevates arterial blood pressure in rats. Peptides 2006; 27:74-9. [PMID: 16023765 DOI: 10.1016/j.peptides.2005.06.011] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/03/2005] [Revised: 06/13/2005] [Accepted: 06/13/2005] [Indexed: 10/25/2022]
Abstract
Intermedin (IMD) is a novel member of the calcitonin/calcitonin gene-related peptide (CGRP) family identified from human and other vertebrate tissues. Preprointermedin can generate various mature peptides by proteolytic cleavage. Amino acid sequence analysis showed cleavage sites located between two basic amino acids at Arg93-Arg94 resulting in the production of prepro-IMD(95-147), namely IMD(1-53). The present study was designed to determine the effects of the IMD(1-53) fragment in the central nervous system (CNS) on mean arterial blood pressure and heart rate in normal rats and its possible mechanism. Rats were given doses of adrenomedullin (ADM) or IMD(1-53), intracerebroventricularly or intravenously, respectively, with continuous blood pressure and heart rate monitoring for 45min. Analysis with CGRP receptor antagonist CGRP(8-37), ADM receptor antagonist ADM(22-52), and anti-prepro-IMD antibody showed that 0.1, 0.5, and 1.0 nmol/kg IMD(1-53), caused a dose-dependent elevation in blood pressure, which was more prominent than the increase with equivalent IMD(1-47) or ADM. As well, IMD(1-53) caused a persistent increase in heart rate. The CNS action of IMD(1-53) could be blocked by ADM(22-52), CGRP(8-37), or prepro-IMD antibody. In contrast to the CNS action, intravenous administration of IMD(1-53) induced a depressor effect. These results suggest that IMD(1-53) is an important regulatory factor in mean arterial blood pressure and heart rate through its central and peripheral bioaction.
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Affiliation(s)
- Yong-Sheng Ren
- Institute of Cardiovascular Disease, Peking University First Hospital, Beijing 100034, China
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Hayashi Y, Ueyama H, Mashimo T, Kangawa K, Minamino N. Circulating mature adrenomedullin is related to blood volume in full-term pregnancy. Anesth Analg 2005; 101:1816-1820. [PMID: 16301265 DOI: 10.1213/01.ane.0000182329.02880.83] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Plasma adrenomedullin concentration increases during pregnancy. We measured blood volume and mature adrenomedullin concentration in plasma and cerebrospinal fluid and examined whether mature adrenomedullin in plasma and cerebrospinal fluid was associated with increasing blood volume during pregnancy. We enrolled 47 women undergoing surgery with spinal anesthesia in this study. We first measured mature adrenomedullin concentration in plasma and cerebrospinal fluid of nonpregnant women undergoing orthopedic surgery, pregnant women between 15 and 18 wk of gestation undergoing gynecological surgery, and pregnant women at full-term undergoing cesarean delivery. The second study included 20 healthy and full-term parturients scheduled for cesarean delivery. We measured arterial blood pressure and blood volume by noninvasive pulse spectrophotometry using indocyanine green. Plasma-mature adrenomedullin concentration was 1.24 +/- 0.98, 2.79 +/- 1.23, 4.79 +/- 2.61 fmol/mL (mean +/- sd) in the nonpregnant, the early gestation, and the full-term groups, respectively. But in cerebrospinal fluid, mature adrenomedullin did not significantly increase. Furthermore, mature adrenomedullin in plasma, but not cerebrospinal fluid, had a significant correlation with blood volume per unit body weight (r2= 0.46; P = 0.0009). These findings demonstrate that plasma-mature adrenomedullin concentration increased and that increased plasma-mature adrenomedullin is associated with increased blood volume during pregnancy.
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Affiliation(s)
- Yukio Hayashi
- *Department of Anesthesiology, Osaka University Faculty of Medicine; and †Japan and Research Institute, National Cardiovascular Center, Suita, Osaka, Japan
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Wu R, Cui X, Dong W, Zhou M, Simms HH, Wang P. Mechanisms responsible for vascular hyporesponsiveness to adrenomedullin after hemorrhage: the central role of adrenomedullin binding protein-1. Ann Surg 2005; 242:115-23. [PMID: 15973109 PMCID: PMC1357712 DOI: 10.1097/01.sla.0000167849.10599.30] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
OBJECTIVE Irreversible hypovolemia remains a major clinical problem. Preliminary studies indicate that administration of adrenomedullin and adrenomedullin binding protein-1 in combination (AM/AMBP-1) after hemorrhage, improves cardiovascular function despite the increased levels of AM. Our aim was to determine whether vascular responsiveness to AM is reduced after hemorrhage and, if so, to elucidate the possible mechanism responsible for such hyporesponsiveness. METHODS Male rats were bled to and maintained at a mean arterial pressure of 40 mm Hg for 90 minutes. The animals were then resuscitated with 4 times the volume of shed blood with lactated Ringer's solution over 60 minutes. At 1.5 hours postresuscitation, vascular responses to AM and AMBP-1, plasma levels of AM and AMBP-1, AMBP-1 and AM receptor gene expression were measured. In additional animals, AM and AMBP-1 were administered intravenously at 15 minutes after resuscitation over 45 minutes. Serum levels of liver enzymes, lactate, creatinine, TNF-alpha, IL-6, and IL-10 were measured at 1.5 hours postresuscitation. RESULTS AM-induced vascular relaxation decreased significantly after hemorrhage and resuscitation, which was markedly improved by AMBP-1. However, AM receptor gene expression did not change under such conditions. Hemorrhage-induced AM hyporesponsiveness was accompanied by the decreased expression and release of AMBP-1. Moreover, AM/AMBP-1 treatment down-regulated TNF-alpha and IL-6, up-regulated IL-10, and attenuated organ injury. CONCLUSIONS The decreased AMBP-1 levels rather than alterations in AM receptors are responsible for producing AM hyporesponsiveness after hemorrhage. Thus, administration of AMBP-1 in combination with AM can be useful to reduce organ injury after severe hypovolemia.
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Affiliation(s)
- Rongqian Wu
- Department of Surgery, North Shore University Hospital and Long Island Jewish Medical Center, Manhasset, NY, USA
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Taylor MM, Samson WK. Stress hormone secretion is altered by central administration of intermedin/adrenomedullin-2. Brain Res 2005; 1045:199-205. [PMID: 15910778 DOI: 10.1016/j.brainres.2005.03.034] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2004] [Revised: 03/16/2005] [Accepted: 03/17/2005] [Indexed: 11/23/2022]
Abstract
Intermedin/Adrenomedullin-2 (IMD), a newly described peptide with structural homology to adrenomedullin (AM), is present in brain and pituitary gland and binds to the same receptors as AM and calcitonin gene-related peptide (CGRP). We hypothesized that IMD would exert actions similar to AM and CGRP and previously have demonstrated that indeed IMD, like AM and CGRP, increases sympathetic tone and inhibits feeding and drinking when administered centrally. Here, we extend those observations by demonstrating that like AM, IMD acts in brain to stimulate the secretions of prolactin (PRL) and adrenocorticotropin (ACTH) and to inhibit the secretion of growth hormone (GH) in conscious rats. In addition, in conscious rats, central administration of IMD results in increased plasma levels of oxytocin (OT) and vasopressin (AVP). The ability of IMD to activate the hypothalamo-pituitary-adrenal (HPA) axis can be blocked by intravenous pretreatment with the corticotropin releasing factor (CRF) antagonist, astressin. These results suggest that multiple members of the AM family of peptides may be involved in the cardiovascular, behavioral and neuroendocrine responses to stress.
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Affiliation(s)
- Meghan M Taylor
- Department of Pharmacological and Physiological Science, Saint Louis University, 1402 South Grand Boulevard, Saint Louis, MO 63104, USA.
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Taylor MM, Bagley SL, Samson WK. Intermedin/adrenomedullin-2 acts within central nervous system to elevate blood pressure and inhibit food and water intake. Am J Physiol Regul Integr Comp Physiol 2005; 288:R919-27. [PMID: 15576658 DOI: 10.1152/ajpregu.00744.2004] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Intermedin (IMD)/adrenomedullin-2 (AM2) is a novel peptide that was independently discovered by two groups. The 47-amino acid peptide is homologous to adrenomedullin (AM) and can activate both the AM and calcitonin gene-related peptide (CGRP) receptors. IMD should therefore have actions similar to those of AM and CGRP. Indeed, like AM and CGRP, intravenous administration of IMD decreased blood pressure in rats and mice. We demonstrate here that immunoreactive IMD is present in plasma as well as heart, lung, stomach, kidney, pituitary, and brain. Because IMD is present in brain and both AM and CGRP have potent central nervous system (CNS) effects, we examined the ability of IMD within brain to regulate blood pressure and ingestive behaviors. Administration of IMD into the lateral cerebroventricle of rats caused significant, long-lasting elevations in mean arterial pressure and heart rate. These elevations are similar to the effects of CGRP and significantly greater than the effects of AM. IMD-induced elevations in mean arterial pressure were inhibited by intravenous administration of phentolamine, indicating that IMD activates the sympathetic nervous system. Intracerebroventricular administration of IMD also inhibited food and water intake in sated and in food- and water-restricted animals. The effects on feeding are likely related to activation of the CGRP receptor and are independent of the effects on water intake, which are likely through the AM receptor. Our data indicate that IMD has potent actions within the CNS that may be a result of the combined activation of both AM and CGRP receptors.
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Affiliation(s)
- Meghan M Taylor
- Department of Pharmacological and Physiological Science, Saint Louis University, 1402 South Grand Boulevard, St. Louis, MO 63104, USA.
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Wu R, Zhou M, Wang P. Adrenomedullin and adrenomedullin binding protein-1 downregulate TNF-alpha in macrophage cell line and rat Kupffer cells. REGULATORY PEPTIDES 2003; 112:19-26. [PMID: 12667621 DOI: 10.1016/s0167-0115(03)00018-1] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Recent studies have demonstrated that administration of adrenomedullin (AM) and AM binding protein-1 (AMBP-1) maintains cardiovascular stability and reduces mortality in sepsis. However, the mechanism responsible for the beneficial effect of AM/AMBP-1 remains unknown. The aim of this study therefore was to determine whether AM/AMBP-1 directly reduces lipopolysaccharide (LPS)-induced secretion of TNF-alpha from murine macrophage-like cell line RAW 264.7 cells and Kupffer cells isolated from normal rats. TNF-alpha release and gene expression were determined by ELISA and RT-PCR, respectively. The results indicated that LPS increased TNF-alpha production from RAW cells by 38-63-fold in a dose- and time-dependent manner. Although incubation with AM or AMBP-1 alone inhibited LPS-induced TNF-alpha release by 14-22% and 13-22%, respectively, AM and AMBP-1 in combination significantly suppressed TNF-alpha production (by 24-35%). Moreover, the upregulated TNF-alpha mRNA by LPS stimulation was significantly reduced by AM/AMBP-1, but not by AM or AMBP-1 alone. In the Kupffer cells primary culture, AM or AMBP-1 alone inhibited LPS-induced TNF-alpha production by 52% and 44%, respectively. Co-culture with AM/AMBP-1 markedly reduced TNF-alpha production (by 90%). Moreover, AM or AMBP-1 alone decreased TNF-alpha mRNA expression by 41% and 36%, respectively, whereas the combination of AM/AMBP-1 decreased its expression by 63%. These results indicate that AM and AMBP-1 in combination effectively suppress LPS-induced TNF-alpha expression and release especially from primary cultured Kupffer cells, suggesting that the downregulatory effect of AM/AMBP-1 on proinflammatory cytokine TNF-alpha may represent a mechanism responsible for their beneficial effects in preventing inflammatory responses and tissue damage in sepsis.
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Affiliation(s)
- Rongqian Wu
- Division of Surgical Research, Department of Surgery, North Shore-Long Island Jewish Medical Center and New York University School of Medicine, 350 Community Drive, Manhasset, NY 11030, USA
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Taylor MM, Samson WK. Ribozyme compromise of adrenomedullin mRNA reveals a physiological role in the regulation of water intake. Am J Physiol Regul Integr Comp Physiol 2002; 282:R1739-45. [PMID: 12010756 DOI: 10.1152/ajpregu.00696.2001] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The adrenomedullin (AM) preprohormone is posttranslationally processed to result in two biologically active fragments, AM and proadrenomedullin NH(2)-terminal 20 peptide (PAMP). AM is thought to play a role in fluid and electrolyte balance by acting in brain to inhibit salt and water appetite and in the kidney to cause diuresis and natriuresis. We previously have shown that AM is necessary for the short-term regulation of salt intake. In this paper, we have designed a ribozyme, a catalytic RNA molecule, which specifically recognizes and cleaves the AM transcript. In cultured vascular smooth muscle cells, ribozyme treatment lowered AM mRNA and reduced peptide content. Intracerebroventricular administration of the ribozyme lowered hypothalamic AM content and led to an exaggerated drinking response in rats, demonstrating that endogenous, brain-derived AM is physiologically relevant and necessary for short-term control of water intake.
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MESH Headings
- Adrenomedullin
- Angiotensin II/administration & dosage
- Animals
- Behavior, Animal/drug effects
- Blotting, Northern
- Cells, Cultured
- Dose-Response Relationship, Drug
- Drinking/drug effects
- Drinking/physiology
- Hypothalamus/drug effects
- Hypothalamus/metabolism
- Injections, Intraventricular
- Male
- Models, Animal
- Muscle, Smooth, Vascular/cytology
- Muscle, Smooth, Vascular/drug effects
- Muscle, Smooth, Vascular/metabolism
- Peptides/genetics
- Peptides/physiology
- RNA, Catalytic/administration & dosage
- RNA, Catalytic/pharmacology
- RNA, Messenger/antagonists & inhibitors
- RNA, Messenger/metabolism
- Rats
- Rats, Sprague-Dawley
- Vasoconstrictor Agents/administration & dosage
- Water Deprivation/physiology
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Affiliation(s)
- Meghan M Taylor
- Department of Pharmacological and Physiological Science, Saint Louis University School of Medicine, St. Louis, Missouri 63104, USA. taylor,
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