Adrenomedullin Research Articles

Selective BMP-9 Inhibition Partially Protects Against Experimental Pulmonary Hypertension.

Although many familial cases of pulmonary arterial hypertension exhibit an autosomal dominant mode of inheritance with the majority having mutations in essential constituents of the BMP (bone morphogenetic protein) signaling, the specific contribution of the long-term loss of signal transduction triggered by the BMPR2 (type 2 BMP receptor) remains poorly characterized. To investigate the role of BMP9, the main ligand of ALK1 (Activin receptor-like kinase 1)/BMPR2 heterocomplexes, in pulmonary hypertension. The absence of BMP9 in Bmp9-/- mice and its inhibition in C57BL/6 mice using neutralizing anti-BMP9 antibodies substantially prevent against chronic hypoxia-induced pulmonary hypertension judged by right ventricular systolic pressure measurement, right ventricular hypertrophy, and pulmonary distal arterial muscularization. In agreement with these observations, we found that the BMP9/BMP10 ligand trap ALK1ECD administered in monocrotaline or Sugen/hypoxia (SuHx) rats substantially attenuate proliferation of pulmonary vascular cells, inflammatory cell infiltration, and regresses established pulmonary hypertension in rats. Our data obtained in human pulmonary endothelial cells derived from controls and pulmonary arterial hypertension patients indicate that BMP9 can affect the balance between endothelin-1, apelin, and adrenomedullin. We reproduced these in vitro observations in mice chronically exposed to hypoxia, with Bmp9-/- mice exhibiting lower mRNA levels of the vasoconstrictor peptide ET-1 (endothelin-1) and higher levels of the 2 potent vasodilator factors apelin and ADM (adrenomedullin) compared with Bmp9+/+ littermates. Taken together, our data indicate that the loss of BMP9, by deletion or inhibition, has beneficial effects against pulmonary hypertension onset and progression.

Bio-adrenomedullin as a marker of congestion in patients with new-onset and worsening heart failure.

Secretion of adrenomedullin (ADM) is stimulated by volume overload to maintain endothelial barrier function, and higher levels of biologically active (bio-) ADM in heart failure (HF) are a counteracting response to vascular leakage and tissue oedema. This study aimed to establish the value of plasma bio-ADM as a marker of congestion in patients with worsening HF. The association of plasma bio-ADM with clinical markers of congestion, as well as its prognostic value was studied in 2179 patients with new-onset or worsening HF enrolled in BIOSTAT-CHF. Data were validated in a separate cohort of 1703 patients. Patients with higher plasma bio-ADM levels were older, had more severe HF and more signs and symptoms of congestion (all P < 0.001). Amongst 20 biomarkers, bio-ADM was the strongest predictor of a clinical congestion score (r2 = 0.198). In multivariable regression analysis, higher bio-ADM was associated with higher body mass index, more oedema, and higher fibroblast growth factor 23. In hierarchical cluster analysis, bio-ADM clustered with oedema, orthopnoea, rales, hepatomegaly and jugular venous pressure. Higher bio-ADM was independently associated with impaired up-titration of angiotensin-converting enzyme inhibitors/angiotensin receptor blockers after 3 months, but not of beta-blockers. Higher bio-ADM levels were independently associated with an increased risk of all-cause mortality and HF hospitalization (hazard ratio 1.16, 95% confidence interval 1.06-1.27, P = 0.002, per log increase). Analyses in the validation cohort yielded comparable findings. Plasma bio-ADM in patients with new-onset and worsening HF is associated with more severe HF and more oedema, orthopnoea, hepatomegaly and jugular venous pressure. We therefore postulate bio-ADM as a congestion marker, which might become useful to guide decongestive therapy.

Midregional proadrenomedullin predicts reduced blood pressure and glucose elevation over time despite enhanced progression of obesity markers.

Elevated plasma levels of the vasodilating hormone adrenomedullin (ADM) predict cardiovascular disease and have been associated with hypertension and obesity. We aimed to examine the independent relationship between ADM and the progression of major cardiometabolic risk factors during long-term follow-up. We studied midregional pro-ADM (MR-proADM) in fasting plasma in 3298 participants from the population-based Malmö Diet and Cancer Study - Cardiovascular Cohort, re-examined after 17 years of follow-up and related baseline MR-proADM to cardiometabolic risk factors cross-sectionally and longitudinally. At baseline, after full adjustment, each SD increment of MR-proADM was independently related to (beta ± standard error, P value) higher SBP (0.956 ± 0.319 mmHg, P = 0.003), BMI (0.912 ± 0.061 kg/m, P = 1.42 × 10), waist (2.28 ± 0.158 cm, P = 8.46 × 10) and fasting blood glucose (0.046 ± 0.018 mmol/l, P = 0.01). After full adjustment, including the baseline level of the risk factor whose degree of progression was studied, each SD increment of MR-proADM predicted significantly reduced progression of SBP (-1.170 ± 0.337 mmHg, P = 0.001) and fasting blood glucose (-0.055 ± 0.023 mmol/l, P = 0.015), but greater increase of BMI (0.101 ± 0.051 kg/m, P = 0.047) and waist (0.600 ± 0.144 cm, P = 3.1 × 10). Despite cross-sectional associations with higher levels of blood pressure and glucose, high levels of MR-proADM predict a slower progression of blood pressure and glycemia during long-term follow-up. Conversely, the cross-sectional associations with higher levels of MR-proADM and obesity were paralleled by a faster progression of obesity markers over time. These results may be important for assessment of long-term effects of therapies modulating levels of ADM.

Preclinical safety evaluation of the adrenomedullin-binding antibody Adrecizumab in rodents, dogs and non-human primates

Adrenomedullin (ADM) is a vasoactive peptide in sepsis. The non-neutralizing ADM-binding antibody Adrecizumab improved outcome in animal models of systemic inflammation and sepsis. Herein, we evaluated the preclinical safety of Adrecizumab in various animal species. First, Wistar rats received vehicle, 100, 200 or 400 mg/kg/day of Adrecizumab intravenously (n = 20 each) on days 1, 4, 8 and 14. An additional set of rats received vehicle or 400 mg/kg/day (n = 10 each) on the same days and were followed for 42 days. For toxicokinetics, satellite animals received vehicle (n = 6), 100, 200, or 400 mg/kg/day Adrecizumab intravenously (n = 18 each). A hemodynamic study was performed in Beagle dogs (n = 3) receiving vehicle (day 1), 2 mg/kg (day 3), 10 mg/kg (day 5), 50 mg/kg (day 8) and 10 mg/kg Adrecizumab intravenously (day 29). In final experiments, cynomolgus monkeys received vehicle, 25, 50 or 100 mg/kg/day Adrecizumab intravenously (n = 6 each) on days 1, 4, 8 and 14. Additional groups of monkeys received vehicle or 100 mg/kg/day Adrecizumab intravenously (n = 4 each) on the same days and were followed for 42 days. No mortality or moribund conditions occurred and no toxicologically relevant effects were attributed to Adrecizumab. Adrecizumab significantly increased circulating concentrations of its target peptide ADM, consistent with previous studies and mechanistically relevant. Toxicokinetic analyses showed immediate and dose-dependent peak concentrations, slow elimination and no gender differences. In conclusion, intravenous, repeated administration of high doses of Adrecizumab appeared well-tolerated across species. These results pave the way for further investigation of Adrecizumab in humans (intended dose of 2 mg/kg).

A double-blind, placebo-controlled, randomised, multicentre, proof-of-concept and dose-finding phase II clinical trial to investigate the safety, tolerability and efficacy of adrecizumab in patients with septic shock and elevated adrenomedullin concentration (AdrenOSS-2)

IntroductionSepsis remains a major health problem with an increasing incidence, high morbidity and high mortality. Apart from treatment with antibiotics and organ support, no approved specific adjunct therapies currently exist....

Adrenomedullin disulfide bond mimetics uncover structural requirements for AM1 receptor activation.

Adrenomedullin (ADM) is a vasoactive peptide hormone of 52 amino acids and belongs to the calcitonin peptide superfamily. Its vasodilative effects are mediated by the interaction with the calcitonin receptor-like receptor (CLR), a class B G protein-coupled receptor (GPCR), associated with the receptor activity modifying protein 2 (RAMP2) and functionally described as AM-1 receptor (AM1 R). A disulfide-bonded ring structure consisting of six amino acids between Cys16 and Cys21 has been shown to be a key motif for receptor activation. However, the specific structural requirements remain to be elucidated. To investigate the influence of ring size and position of additional functional groups that replace the native disulfide bond, we generated ADM analogs containing thioether, thioacetal, alkane, and lactam bonds between amino acids 16 and 21 by Fmoc/t-Bu solid phase peptide synthesis. Activity studies of the ADM disulfide bond mimetics (DSBM) revealed a strong impact of structural parameters. Interestingly, an increased ring size was tolerated but the activity of lactam-based mimetics depended on its position within the bridging structure. Furthermore, we found the thioacetal as well as the thioether-based mimetics to be well accepted with full AM1 R activity. While a reduced selectivity over the calcitonin gene-related peptide receptor (CGRPR) was observed for the thioethers, the thioacetal was able to retain a wild-type-like selectivity profile. The carbon analog in contrast displayed weak antagonistic properties. These results provide insight into the structural requirements for AM1 R activation as well as new possibilities for the development of metabolically stabilized analogs for therapeutic applications of ADM.

Development of a Novel Model of Central Retinal Vascular Occlusion and the Therapeutic Potential of the Adrenomedullin–Receptor Activity–Modifying Protein 2 System

Central retinal vein occlusion (CRVO) is an intractable disease that causes visual acuity loss with retinal ischemia, hemorrhage, and edema. In this study, we developed an experimental CRVO model in mice and evaluated the therapeutic potential of the pleiotropic peptide adrenomedullin (ADM) and its receptor activity-modifying protein 2 (RAMP2). The CRVO model, which had phenotypes resembling those seen in the clinic, was produced by combining i.p. injection of Rose bengal, a photoactivator dye enhancing thrombus formation, with laser photocoagulation. Retinal vascular area, analyzed using fluorescein angiography and fluorescein isothiocyanate-perfused retinal flat mounts, was decreased after induction of CRVO but gradually recovered from day 1 to 7. Measurements of retinal thickness using optical coherence tomography and histology revealed prominent edema early after CRVO, followed by gradual atrophy. Reperfusion after CRVO was diminished in Adm and Ramp2 knockout (KO) mice but was increased by exogenous ADM administration. CRVO also increased expression of a coagulation factor, oxidative stress markers, and a leukocyte adhesion molecule in both wild-type and Adm KO mice, and the effect was more pronounced in Adm KO mice. Using retinal capillary endothelial cells, ADM was found to directly suppress retinal endothelial injury. The retinoprotective effects of the Adm-Ramp2 system make it a novel therapeutic target for the treatment of CRVO.

Downregulation of Adrenomedullin Leads to the Inhibition of the Tumorigenesis via VEGF Pathway in Human and Nude Mice Osteosarcoma Models

Osteosarcoma is one of the most pernicious primary bone tumor characterized by high malignancy and metastasis, however its pathogenesis remain largely unknown. Our previous study showed elevated expression of adrenomedullin (ADM) is correlated with prognosis and disease severity in osteosarcoma patients. In this research, we continue to study the mechanisms of ADM-induced osteosarcoma cells proliferation invitro and invivo osteosarcoma models. The Radioimmunoassay was used to test the correlations of ADM and vascular endothelial growth factor (VEGF) expressions in plasma of osteosarcoma patients. The MTT and flow cytometry analysis were accepted to monitor the proliferation of osteosarcoma cells, meanwhile the ADM and VEGF expression were detected by real-time PCR and western blot. Moreover, the relationship among ADM and VEGF expression was also assessed in the osteosarcoma nude mice models. In this study, a significant correlation was found between ADM and VEGF expression in the plasma of osteosarcoma patients. As important stimuli in osteosarcoma proliferation, hypoxia could stimulate ADM and VEGF expression in MG-63cells. The expressions of ADM and VEGF increased with the duration of hypoxia, which also identify the positive correlations between the expression of ADM and VEGF. The proliferation of MG-63cells decreased when ADM was inhibited. And the proliferation increased when adding exogenous ADM, while VEGF inhibition attenuated this effect. Furthermore, ADM reduction also inhibited VEGF, CD31 expression and tumor cells growth in osteosarcoma nude mice models. These results suggested inhibition of osteosarcoma cells proliferation might be influenced by ADM through VEGF pathway, which implied ADM-VEGF signal was a potential target for impeding the proliferation of malignant cells in osteosarcoma.

Plasma Endothelin-1 and Adrenomedullin are Associated with Coronary Artery Function and Cardiovascular Outcomes in Humans

Abstract Background Endothelin-1 (ET-1) is a vasoconstrictor associated with cardiovascular disease, whereas adrenomedullin (ADM) is a vasorelaxant with cardioprotective properties. We sought to determine the relationship between plasma ET-1 and ADM with coronary circulatory function and long-term major adverse cardiovascular events (MACE). Methods Thirty-two patients undergoing coronary angiography for chest pain were recruited. Baseline plasma ET-1 and ADM levels were measured. The index of microcirculatory resistance (IMR), coronary flow mediated dilatation (cFMD) and coronary flow reserve (CFR) were measured in a non-obstructed coronary artery. Patients were assessed for MACE over a median period of 8.8 years. Results Plasma ET-1 levels correlated with IMR (r = 0.57; p Conclusions Plasma ET-1 and ADM were associated with measures of coronary microvascular and coronary conduit vessel function, respectively. Increased cFMD and elevated plasma ADM were associated with a cardioprotective effect.

Early and late endothelial response in breast cancer metastasis in mice: simultaneous quantification of endothelial biomarkers using a mass spectrometry-based method.

ABSTRACTThe endothelium plays an important role in cancer metastasis, but the mechanisms involved are still not clear. In the present work, we characterised the changes in endothelial function at early and late stages of breast cancer progression in an orthotopic model of murine mammary carcinoma (4T1 cells). Endothelial function was analysed based on simultaneous microflow liquid chromatography–tandem mass spectrometry using multiple reaction monitoring (microLC/MS-MRM) quantification of 12 endothelium-related biomarkers, including those reflecting glycocalyx disruption – syndecan-1 (SDC-1), endocan (ESM-1); endothelial inflammation – vascular cell adhesion molecule 1 (VCAM-1), intercellular adhesion molecule 1 (ICAM-1), E-selectin (E-sel); endothelial permeability – fms-like tyrosine kinase 1 (FLT-1), angiopoietin 2 (Angpt-2); and haemostasis – von Willebrand factor (vWF), tissue plasminogen activator (t-PA), plasminogen activator inhibitor 1 (PAI-1), as well as those that are pathophysiologically linked to endothelial function – adrenomedullin (ADM) and adiponectin (ADN). The early phase of metastasis in mouse plasma was associated with glycocalyx disruption (increased SDC-1 and ESM-1), endothelial inflammation [increased soluble VCAM-1 (sVCAM-1)] and increased vascular permeability (Angpt-2). During the late phase of metastasis, additional alterations in haemostasis (increased PAI-1 and vWF), as well as a rise in ADM and substantial fall in ADN concentration, were observed. In conclusion, in a murine model of breast cancer metastasis, we identified glycocalyx disruption, endothelial inflammation and increased endothelial permeability as important events in early metastasis, while the late phase of metastasis was additionally characterised by alterations in haemostasis.

Adrenomedullin gene polymorphisms ( rs4399321A/G and rs4910118C/T ) in pregnancy related disorder: Preeclampsia

Preeclampsia (PE), a pregnancy specific vascular disorder which is characterized by hypertension and proteinuria is a leading cause of maternal, fetal/neonatal morbidity and mortality affecting 5-14% of pregnancies. PE is a multifactorial disorder associated with poor placentation, placental hypoxia, poor angiogenesis and excessive maternal inflammation. Adrenomedullin (ADM) is a multifunctional peptide, plays an important role in the establishment and maintenance of healthy pregnancy, prevents an immune attack at peri-implantation period, vasodilation and promotes angiogenesis. In the present study, we enrolled a total of 600 subjects which includes 300 PE patients and 300 healthy pregnant women from South India to analyse two functional polymorphisms (rs4399321A/G and rs4910118C/T) of ADM gene. The genotype frequencies of these two polymorphisms differed significantly between the PE and control groups (p=0.02 and p=0.03). Individuals carrying the AA genotype of rs4399321A/G were slightly higher in controls (40%) compared to patients (28%) and revealed an OR value of (0.69, CI 0.49-0.98; p=0.05) suggests the protective role. Predominant frequency of CC genotype of rs4910118C/T was observed in patients (OR- 1.43; CI 1.02–2.01, p=0.04) and CT genotype in controls (OR-0.69; CI 0.49–0.97, p=0.04) indicating predisposing and protective role of these genotypes. Haplotype analysis revealed a substantial association of A-T block towards preeclampsia with an OR value of 0.40 (CI 0.21-0.75, p=0.004). Further analysis on linkage disequilibrium showed a significant value (D’=1.0 and r2=0.12, p<0.05) between these two polymorphisms.

Adrenomedullin in heart failure: pathophysiology and therapeutic application.

Adrenomedullin (ADM) is a peptide hormone first discovered in 1993 in pheochromocytoma. It is synthesized by endothelial and vascular smooth muscle cells and diffuses freely between blood and interstitium. Excretion of ADM is stimulated by volume overload to maintain endothelial barrier function. Disruption of the ADM system therefore results in vascular leakage and systemic and pulmonary oedema. In addition, ADM inhibits the renin–angiotensin–aldosterone system. ADM is strongly elevated in patients with sepsis and in patients with acute heart failure. Since hallmarks of both conditions are vascular leakage and tissue oedema, we hypothesize that ADM plays a compensatory role and may exert protective properties against fluid overload and tissue congestion. Recently, a new immunoassay that specifically measures the biologically active ADM (bio‐ADM) has been developed, and might become a biomarker for tissue congestion. As a consequence, measurement of bio‐ADM might potentially be used to guide diuretic therapy in patients with heart failure. In addition, ADM might be used to guide treatment of (pulmonary) oedema or even become a target for therapy. Adrecizumab is a humanized, monoclonal, non‐neutralizing ADM‐binding antibody with a half‐life of 15 days. Adrecizumab binds at the N‐terminal epitope of ADM, leaving the C‐terminal side intact to bind to its receptor. Due to its high molecular weight, the antibody adrecizumab cannot cross the endothelial barrier and consequently remains in the circulation. The observation that adrecizumab increases plasma concentrations of ADM indicates that ADM‐binding by adrecizumab is able to drain ADM from the interstitium into the circulation. We therefore hypothesize that administration of adrecizumab improves vascular integrity, leading to improvement of tissue congestion and thereby may improve clinical outcomes in patients with acute decompensated heart failure. A phase II study with adrecizumab in patients with sepsis is ongoing and a phase II study on the effects of adrecizumab in patients with acute decompensated heart failure with elevated ADM is currently in preparation.

Genetic loss of proadrenomedullin N-terminal 20 peptide (PAMP) in mice is compatible with survival

Adrenomedullin (AM) and proadrenomedullin N-terminal 20 peptide (PAMP) are small peptides derived from a common precursor, pre-proadrenomedullin. Although AM and PAMP share hypotensive effects in the cardiovascular system, the peptides also exert diverse and distinct effects on endocrine physiology, innate immunity, cytoskeletal biology and receptor signaling pathways. Tremendous knowledge has been gleaned from the study of several genetic animal models of AM deletion or overexpression, some of which also simultaneously delete the coding region for PAMP peptide. However, deletion of PAMP without concurrent deletion of AM in an animal model is not currently available for the study of PAMP function. Here, we present the generation of AdmΔPAMP/ΔPAMP and AdmΔPAMP/− mice, which lack the coding sequence for PAMP while preserving the coding sequence for AM. AdmΔPAMP/ΔPAMP mice survive to adulthood without any obvious abnormalities and are fertile, though AdmΔPAMP/− females have small litters. Interestingly, these animals express lower levels of Adm mRNA and AM peptide than wild type animals, but these levels are still compatible with survival. Importantly, despite reduced levels, the spatiotemporal expression of AM peptide within the hearts of AdmΔPAMP/− mice remains similar to wild type animals. AdmΔPAMP/ΔPAMP mice are now a publicly available tool for future investigations of PAMP function.

Effect of experimentally induced hypertension on cerebellum of postmenopausal rat.

Cerebellum seems to be a specific target for both the decrease of estrogen and hypertension in menopause. The aim of this study was to investigate the hypertension and menopause-induced changes in rat's cerebellar cortex and the possible mechanisms of these changes. Rats were divided into four groups: the sham-operated control (SC-group), the ovariectomized (OVX-group), the hypertensive (H-group), and the ovariectomized-hypertensive (OVX-H-group) group. The mean arterial pressure (MAP), serum nitric oxide (NO), lipid peroxides and antioxidant catalase enzyme levels were assayed. Cerebellar tissue homogenization for analysis of lipid peroxides, antioxidant catalase enzyme, tumor necrosis factor-α (TNF-α), and estradiol was done. Quantification of adrenomedullin (AM) and interleukin-10 (IL-10) mRNA was also done. Cerebella were processed for histological, immunohistochemical and transmission electron microscopic examination. In the OVX-group, insignificant structural and biochemical changes were observed compared with the SC-group apart from the significantly increased lipid peroxides and decreased NO and catalase levels in serum. The H-group showed an elevated lipid peroxides and TNF-α levels, reduced catalase level, numerous degenerated Purkinje cells, vacuolations of the neuropil, some axonal degeneration, and few ghosts in the granular cell layer (GL). However, in OVX-H-group, oxidative stress, inflammation, and cerebellar damage were exacerbated and cerebellar estrogen was reduced associated with reduction in GL thickness and decreased Purkinje cells number. Most axoplasms had degenerated neurofilaments with abnormal myelination. The immunoexpression of glial fibrillary acidic protein were significantly increased in both OVX-group and H-group and significantly decreased in OVX-H group. Gene expression of AM and IL-10 were increased in cerebellar tissues of H-group compared with the SC-group but it was significantly decreased in OVX-H-group compared with H-group. Taken together, postmenopausal rats with hypertension suffered from structural cerebellar changes than rats with only hypertension or estrogen deficiency separately due to augmentation of the increased oxidative stress markers and the proinflammatory cytokines (TNF-α) with down regulation of the anti-inflammatory cytokine (IL-10) and the blood pressure regulator, AM. These suggested that high blood pressure is a critical factor for postmenopausal cerebellum.

Effects of the Humanized Anti-Adrenomedullin Antibody Adrecizumab (HAM8101) on Vascular Barrier Function and Survival in Rodent Models of Systemic Inflammation and Sepsis.

Adrenomedullin (ADM) is an important regulator of endothelial barrier function during sepsis. Administration of a murine antibody targeted against the N-terminus of ADM (HAM1101) resulted in improved outcome in models of murine sepsis. We studied the effects of a humanized form of this antibody (HAM8101, also known as Adrecizumab) on vascular barrier dysfunction and survival in rodent models of systemic inflammation and sepsis. Rats (n=48) received different dosages of HAM8101 or placebo (n = 8 per group), directly followed by administration of lipopolysaccharide (5 mg/kg). Twenty-four hours later, Evans Blue dye was administered to assess vascular leakage in kidney and liver tissue. Furthermore, mice (n = 24) were administered different dosages of HAM8101 or placebo (n = 6 per group), immediately followed by cecal ligation and puncture (CLP). Eighteen hours later, albumin, vascular endothelial growth factor (VEGF), and angiopoietin-1 were analyzed in the kidney. Finally, effects of single and repeated dose administration of HAM1101, HAM8101 and placebo on survival were assessed in CLP-induced murine sepsis (n = 60, n = 10 per group). Dosages of 0.1 and 2.5 mg/kg HAM8101 attenuated renal albumin leakage in endotoxemic rats. Dosages of 0.1, 2.0, and 20 mg/kg HAM8101 reduced renal concentrations of albumin and the detrimental protein VEGF in septic mice, whereas concentrations of the protective protein angiopoietin-1 were augmented. Both single and repeated administration of both HAM1101 and HAM8101 resulted in improved survival during murine sepsis. Pretreatment with the humanized anti-ADM antibody HAM8101 improved vascular barrier function and survival in rodent models of systemic inflammation and sepsis.

Adrenomedullin and glucagon-like peptide-1 have additive effects on food intake in mice

Adrenomedullin (ADM) is a vasoactive peptide expressed in several peripheral organs and known primarily for its beneficial vasoactive effects. However, ADM is also known to inhibit insulin secretion, and central administration of ADM has been shown to elicit anorexigenic effects. Here, we investigated if peripheral co-administration of ADM and glucagon-like peptide 1 (GLP-1) could subdue the hypoglycaemic effects of ADM while enhancing its anorectic properties.The effects of mono- and combination therapy of ADM and GLP-1 on appetite regulation and glucose homeostasis were assessed acutely in male NMRI mice for 12 h, while effects on glucose homeostasis were assessed by oral glucose tolerance tests (OGTT).While the monotherapy with GLP-1 and ADM resulted in modest anorexigenic effects, co-administration of the two peptides led to a marked additive reduction in food intake. Moreover, while OGTT-evoked blood glucose-excursions were significantly increased by ADM monotherapy, co-administration of ADM with a lower dose of GLP-1 normalized glucose excursions.In conclusion, we demonstrate additive anorectic effects of ADM and GLP-1, and that GLP-1 co-administration prevents ADM-induced impairment of glucose tolerance, suggesting that ADM could be potential anti-obesity target when combined with GLP-1 agonist therapy.

Association of brain natriuretic peptide and adrenomedullin plasma levels with left ventricular filling pressures in end-stage renal disease patients on hemodialysis.

Adrenomedullin (ADM) and brain natriuretic peptide (BNP) are known to be associated with elevated left ventricular filling pressures. However, little is known about this association in hemodialysis (HD) patients with preserved left ventricular ejection fraction (LVEF). Our objective was to evaluate the potential association between E/e' ratio and plasma levels of BNP and ADM in end-stage renal disease (ESRD) patients with preserved LVEF undergoing chronic hemodialysis. The study group enrolled 62 ESRD patients treated with hemodialysis three times weekly. BNP and ADM plasma concentration measurements and echocardiographic examination were performed 30 minutes after hemodialysis. E/e' ratio, evaluated by Tissue Doppler imaging and measured at the basal septum, was used as a surrogate marker for assessing left ventricular filling pressures. The mean age of patients was 62 ± 25 years. The mean BNP and ADM values after hemodialysis were 0.40 ± 6.73 ng/ml and 0.06 ± 2.12 ng/ml, respectively. Elderly patients with hypertrophied left ventricles and larger left atria displayed higher E/e' values. BNP (r = 0.324. p = 0.018) and ADM (r = 0.319, p = 0.042) plasma levels were positively and significantly associated with E/e΄. Multivariate regression analysis including BNP, ADM, age, hemodialysis duration, left ventricular end-systolic volume index, LVEF, left ventricular mass index and left atrium volume index, revealed that ADM (p-value 0.025) but not BNP levels, were independently associated with the E/e' ratio. ADM, but not BNP, was independently associated with septal E/e' in HD patients with preserved LVEF. ADM plasma levels can be used as a surrogate index to assess left ventricular filling pressures in HD patients.

Circulating Adrenomedullin Is Elevated in Gestational Diabetes and Its Role in Impaired Insulin Production by β-Cells.

Defective pancreatic β-cell adaptation in pregnancy plays an important role in the pathophysiology of gestational diabetes mellitus (GDM), but the molecular basis remains unclear. Objectives of this study were to determine if circulating levels of adrenomedullin (ADM) in women with GDM are elevated and to assess the effects of ADM on insulin synthesis and secretion by human pancreatic β-cells. A stable gene product of ADM precursor, midregional pro-adrenomedullin(MR-proADM), was measured in plasma of pregnant women with normal glucose tolerance (NGT, n = 10) or GDM (n = 11). The β-Lox5 cell line, derived from human pancreatic β-cells, was transduced with homeodomain transcription factor pancreatic-duodenal homeobox (PDX) factor 1 (PDX1) encoding lentiviral vector and treated with different doses of ADM. mRNA for insulin, ADM, and its receptor components in β-Lox5 cells and insulin in media were measured. Plasma MR-proADM levels were significantly higher in GDM compared with patients with NGT. Pancreatic β-Lox5 cells express mRNA for insulin, ADM, and its receptor components. PDX1 transduction and cell-cell contact synergistically promote β-Lox5 cells insulin mRNA and secretion. Furthermore, ADM dose-dependently inhibited mRNA and secretion of insulin in β-Lox5 cell aggregates. These inhibitory effects were blocked by ADM antagonist ADM22-52, cAMP-dependent protein kinase A inhibitor KT5720, and Erk inhibitor PD98059, but not by PI-3K the inhibitor wortmannin. Circulating ADM concentrations were elevated in pregnant women with GDM. ADM suppresses insulin synthesis and secretion by pancreatic β-cells in vitro. Thus, increased circulating ADM may contribute to the defective adaptation of β-cells in diabetic pregnancies, and blockade of ADM actions with its antagonists may improve β-cell functions.

RAMP3 deficiency enhances postmenopausal obesity and metabolic disorders

There is a marked increase in the incidence of visceral adiposity and insulin resistance among women following menopause. Adrenomedullin (AM) is an endogenous peptide first identified as a vasodilator, but now known to exert a variety of physiological effects. RAMP3 is a receptor activity-modifying protein that binds to the AM receptor (calcitonin receptor-like receptor). As expression of both AM and RAMP3 is reportedly activated by estrogen, we hypothesized that RAMP3 is crucially involved in the pathophysiology of postmenopausal obesity. To test this idea, we compared the effects of ovariectomy (OVX) and a high-fat diet for 10 weeks (a model of postmenopausal obesity) between RAMP3 knockout (RAMP3-/-) and wild-type mice. RAMP3-/- OVX mice exhibited greater obesity and adipose tissue weight gain as compared to wild-type OVX mice. RAMP3-/- OVX mice also exhibited higher serum insulin levels. In periuterine WAT from RAMP3-/- OVX mice, expression of lipolysis-related factors was lower and expression of inflammation-related factors was higher than in wild-type OVX mice. Hepatic steatosis was also exacerbated in RAMP3-/- OVX. Notably, expression of the membrane-type estrogen receptor GPR30 was downregulated in periuterine WAT from RAMP3-/- OVX mice. These findings raise the possibility that a GPR30-RAMP3 interaction is involved in the pathophysiology of postmenopausal obesity and suggest RAMP3 plays a key role in the regulation of energy metabolism and exerts a hepatoprotective effect in this model of postmenopausal obesity. RAMP3 may thus be a useful therapeutic target for treatment of postmenopausal obesity and metabolic disorders.

Intrathecal administration of adrenomedullin induces mechanical allodynia and neurochemical changes in spinal cord and DRG

This study investigated the effect of adrenomedullin (AM) on mechanical pain sensitivity and its possible mechanisms. Intrathecal injection of AM receptor agonist AM1-50 (20 μg) once per day briefly reduced mechanical pain threshold on days 1 and 2 but induced prolonged mechanical allodynia on day 3. However, AM1-50 did not change mechanical pain sensation when the AM receptor antagonist AM22-52 (20 μg) was intrathecally co-administered. Daily administration of AM1-50 (20 μg) for 3 days increased expression of phosphorylated extracellular signal-regulated protein kinase (pERK) and neuronal nitric oxide synthase (nNOS) in the spinal dorsal horn. The AM-induced increase in pERK and nNOS was inhibited by the co-administration of AM22-52. The chronic administration of AM1-50 also increased expression of microglial maker Iba1 and astrocytic marker GFAP (glial fibrillary acidic protein) in the spinal dorsal horn in an AM22-52-sensitive manner. Furthermore, the application of AM1-50 (10 nM, 3 h) to dorsal root ganglion (DRG) explant cultures induced an increase in the expression of transient receptor potential vanilloid 1 (TRPV1). The treatment with AM1-50 did not change TRPV1 expression in DRG in the presence of AM22-52 (2 μM). These results suggest that the increased AM bioactivity induced mechanical allodynia and may contribute to the mechanical pain hypersensitivity under pathological conditions. The mechanisms may involve the activation of ERK signaling pathway and spinal glia as well as the recruitment of nNOS and TRPV1 in the spinal dorsal horn or DRG. The present study indicates that inhibition of the activation AM receptor might provide a fruitful strategy to relieving chronic pain.