Expression Levels Of Adrenomedullin Research Articles

Adrenomedullin Expression Is Associated With the Severity and Poor Prognosis of Interstitial Lung Disease in Dermatomyositis Patients.

ObjectiveTo evaluate adrenomedullin mRNA levels in the peripheral blood mononuclear cells (PBMCs) of patients with dermatomyositis (DM) as well as their correlation with the severity of interstitial lung disease (ILD).MethodsA total of 41 DM patients and seven immune-mediated necrotizing myopathy (IMNM) patients were recruited, in addition to 21 healthy controls (HCs). The adrenomedullin mRNA levels in PBMCs were measured via quantitative reverse-transcription real-time polymerase chain reaction (qRT-PCR). The associations between adrenomedullin expression levels and major clinical, laboratory, pulmonary function parameters and the prognosis of patients with DM-related ILD (DM-ILD) were analyzed. Immunohistochemical analysis was performed on lung tissues of DM-ILD patients to determine adrenomedullin expression.ResultsAdrenomedullin mRNA levels in PBMCs were significantly higher in DM patients than in IMNM patients and HCs (p = 0.022 and p<0.001, respectively). Among DM patients, the levels were significantly higher in those with rapidly progressive ILD (RP-ILD) than in those with chronic ILD (p = 0.002) or without ILD (p < 0.001). The adrenomedullin mRNA levels in DM-ILD were positively correlated with serum ferritin (r =0.507, p =0.002), lactate dehydrogenase (LDH) (r =0.350, p =0.045), and lung visual analog scale (VAS) (r=0.392, p=0.021) and were negatively correlated with pulmonary function test parameters, including predicted forced vital capacity (FVC)% (r = −0.523, p = 0.025), forced expiratory volume in 1 s (FEV1)% (r = -0.539, p = 0.020), and diffusing capacity of carbon monoxide (DLco)% (r = -0.495, p = 0.036). Immunohistochemical analysis of adrenomedullin confirmed higher expression in the alveolar epithelial cells and macrophages of DM patients with RP-ILD. Among the DM patients with ILD, the six decedents exhibited higher adrenomedullin levels than the 28 survivors (p = 0.042). The cumulative survival rate was significantly lower (62.5% vs. 100%, P = 0.005) in patients with an adrenomedullin level > 0.053 than in those with a level <0.053.ConclusionsAdrenomedullin levels are upregulated in DM patients with RP-ILD and are associated with ILD severity and poor prognosis. Adrenomedullin may be a potential prognostic biomarker in DM patients with ILD, although need further investigation.

Protective effect of adrenomedullin on hyperoxia-induced lung injury.

To study the role of adrenomedullin (ADM) in hyperoxia-induced lung injury by examining the effect of ADM on the expression of calcitonin receptor-like receptor (CRLR), receptor activity-modifying protein 2 (RAMP2), extracellular signal-regulated kinase (ERK), and protein kinase B (PKB) in human pulmonary microvascular endothelial cells (HPMECs) under different experimental conditions. HPMECs were randomly divided into an air group and a hyperoxia group (n=3 each).The HPMECs in the hyperoxia group were cultured in an atmosphere of 92% O2 (3 L/minute) +5% CO2. RT-qPCR and Western blot were used to measure the mRNA and protein expression levels of ADM, CRLR, RAMP2, ERK1/2, and PKB. Other HPMECs were divided into a non-interference group and an interference group (n=3 each), and the mRNA and protein expression levels of ADM, ERK1/2, and PKB were measured after the HPMECs in the interference group were transfected with ADM siRNA. Compared with the air group, the hyperoxia group had significant increases in the mRNA and protein expression levels of ADM, CRLR, RAMP2, ERK1/2, and PKB (P<0.05). Compared with the non-interference group, the interference group had significant reductions in the mRNA and protein expression levels of ADM, ERK1/2, and PKB (P<0.05). ERK1/2 and PKB may be the downstream targets of the ADM signaling pathway. ADM mediates the ERK/PKB signaling pathway by regulating CRLR/RAMP2 and participates in the protection of hyperoxia-induced lung injury.

Altered expression of ADM and ADM2 by hypoxia regulates migration of trophoblast and HLA-G expression†.

Preeclampsia (PE) is a placental disorder caused by endothelial dysfunction via trophoblast inadequate invasion activity. Adrenomedullin (ADM) and ADM2 are multifunctional peptides that can support vascular activity and placental growth. However, correlation between ADMs and trophoblast functions is currently unclear. The objective of this study was to analyze changes in expression of ADMs in placenta and HTR-8/SVneo trophoblast cells under hypoxia and their effects on invasion activity of trophoblast cells and expression of HLA-G. In placental tissues of PE, expression levels of ADM and HLA-G were significantly increased (P < 0.05) whereas expression of ADM2 was decreased compared to that in normal term placenta. Under hypoxia, expression levels of ADM, ADM2, and HLA-G and invasion ability of trophoblast cells were increased in hypoxia-inducible factor-1 (HIF-1α)- dependent manner (P < 0.05). Treatment with ADMs agonists reduced HIF-1α activity whereas enhanced invasion ability under hypoxia. However, they were not changed after cotreatment of ADMs and HIF-1α inhibitor, YC-1, although expression levels of invasion-related genes MMP2, MMP9, and Rac1 were altered (P < 0.05). ADMs also increased HLA-G expression under normoxia whereasADM2 or cotreatment of ADMs under hypoxia attenuated HLA-G expression (P < 0.05). Our findings demonstrate that altered expression of ADMs plays a critical role in placental physiology, especially in trophoblast invasion and immune-modulation under hypoxia.

Adrenomedullin expression in aortic artery wall of diabetic rats given alpha lipoic acid.

Diabetes mellitus (DM) is a major health problem predisposing to cardiovascular diseases. The aim of this study was to investigate the effects of alpha lipoic acid (ALA) on both the arterial wall of diabetic rats and the adrenomedullin (ADM) gene expression. Twenty-four Wistar Albino rats were divided into three groups as Control, DM + S, and DM + ALA. For DM model, a single dose of 40mg/kg streptozotocin, for DM + ALA group, 100mg/kg/day/4weeks was administered. Hematoxylin & Eosin (H&E) staining was done and vascular endothelial growth factor (VEGF) was detected by immunohistochemical analysis in the artery wall. Total damage score of vessel wall (endothelial cell damage, media layer smooth muscle cell damage, and internal elastic lamina damage) and H score (immunoreactivity intensity) were calculated. Expression of ADM gene was measured by qRT-PCR. In DM + S group, Total damage score of vessel wall were detected by light microscopy. There were statistically significant differences between the groups Control/DM + S and DM + S/DM + ALA in terms of the vessel total damage score and H score (p < 0.005). ADM expression was increased threefold in both DM + S and DM + ALA groups compared to the control group (p < 0.05). ALA may have positive effect on the vessel damage in diabetic rats. However, no significant decrease in ADM expression levels was observed in diabetic rats after ALA administration and we considered that the protective effect of ALA is independent of adrenomedullin. Further studies with different doses and durations of ALA administrations are required to investigate the changes in ADM expression.

Overexpression of adrenomedullin protects mesenchymal stem cells against hypoxia and serum deprivation‑induced apoptosis via the Akt/GSK3β and Bcl‑2 signaling pathways.

The poor survival rate of transplanted mesenchymal stem cells (MSCs) within the ischemic heart limits their therapeutic potential for cardiac repair. Adrenomedullin (ADM) has been identified as a potent apoptotic inhibitor. The present study aimed to investigate the protective effects of ADM on MSCs against hypoxia and serum deprivation (H/SD)-induced apoptosis, and to determine the potential underlying mechanisms. In the present study, a recombinant adenovirus expressing the ADM gene was established and was infected into MSCs. The infection rate was determined via microscopic detection of green fluorescence and flow cytometric analysis. The mRNA expression levels of ADM were detected by reverse transcription-polymerase chain reaction. In addition, a model of H/SD was generated. The MSCs were randomly separated into six groups: Control, enhanced green fluorescent protein (EGFP)-Adv, EGFP-ADM, H/SD, EGFP-Adv + H/SD and EGFP-ADM + H/SD. Cell viability and proliferation were determined using the Cell Counting kit-8 assay. Apoptosis was assessed by terminal deoxynucleotidyl transferase-mediated-dUTP nick-end labeling assay and flow cytometric analysis using Annexin V-phycoerythrin/7-aminoactinomycin D staining. The protein expression levels of total protein kinase B (Akt), phosphorylated (p)-Akt, total glycogen synthase kinase (GSK)3β, p-GSK3β, B-cell lymphoma 2 (Bcl-2), Bcl-2-associated X protein (Bax), caspase-3 and cleaved caspase-3 were detected by western blot analysis. The results indicated that ADM overexpression could improve MSC proliferation and viability, and protect MSCs against H/SD-induced apoptosis. In addition, ADM overexpression increased Akt and GSK3β phosphorylation, and Bcl-2/Bax ratio, and decreased the activation of caspase-3. These results suggested that ADM protects MSCs against H/SD-induced apoptosis, which may be mediated via the Akt/GSK3β and Bcl-2 signaling pathways.

Expression of peptide fragments from proADM and involvement of mitogen-activated protein kinase signaling pathways in pulmonary remodeling induced by high pulmonary blood flow.

Pulmonary arterial hypertension (PAH) is a life-threatening disease characterized by progressive pulmonary arterial remodeling and right ventricular failure. Despite recent advances in pathophysiological mechanism exploration and new therapeutic approaches, PAH remains a challenging condition. In this study, we investigated the roles of the peptide fragments from proadrenomedullin (proADM) such as adrenomedullin (ADM), adrenotensin (ADT), and proadrenomedullin N-terminal 20 peptide (PAMP) during pulmonary remodeling caused by high pulmonary blood flow, and probed the possible involvement of mitogen-activated protein kinase (MAPK) signal transduction pathways. Sixteen rat models of PAH were artificially established by surgically connecting the left common carotid artery to the external jugular vein. We subcutaneously injected an extracellular signal-regulated protein kinase (ERK1/2) inhibitor, PD98059, in eight rats, treated another eight rats with an equal volume of saline. Eight rats without connections served as the control group. We observed that mRNA expression levels of ADM, stress-activated protein kinase (SAPK), and ERK1/2 were significantly elevated in the shunted rats; furthermore, ERK1/2 levels were significantly inhibited by PD98059. Protein levels of ADM, PAMP, p-SAPK, and p-ERK1/2 were significantly higher ADT was lower, and p-p38 remained unchanged in the rat models compared with the controls. However, the protein expression of both ADM and p-ERK1/2 was significantly inhibited by PD98059. Our results suggest that levels of ADM, ADT, and PAMP respond to pulmonary remodeling, and that activation of the SAPK and ERK1/2 signaling pathways is involved in pulmonary hypertension and artery remodeling caused by high pulmonary blood flow.

Lysophosphatidic acid increases the proliferation and migration of adipose‑derived stem cells via the generation of reactive oxygen species.

Phospholipid derivatives, such as lysophosphatidic acid (LPA), exhibit mitogenic effects on mesenchymal stem cells; however, the molecular mechanism underlying this stimulation has yet to be identified. The aims of the present study were as follows: To evaluate the stimulatory effects of LPA on the proliferation and migration of adipose‑derived stem cells (ASCs); to study the association between reactive oxygen species (ROS) and LPA signaling in ASCs; and to investigate the microRNAs upregulated by LPA treatment in ASCs. The results of the present study demonstrated that LPA increased the proliferation and migration of ASCs, and acted as a mitogenic signal via extracellular signal‑regulated kinases 1/2 and the phosphoinositide 3‑kinase/Akt signaling pathways. The LPA1 receptor is highly expressed in ASCs, and pharmacological inhibition of it by Ki16425 significantly attenuated the proliferation and migration of ASCs. In addition, LPA treatment generated ROS via NADPH oxidase 4, and ROS were able to function as signaling molecules to increase the proliferation and migration of ASCs. The induction of ROS by LPA treatment also upregulated the expression of miR‑210. A polymerase chain reaction array assay demonstrated that the expression levels of adrenomedullin and Serpine1 were increased following treatment with LPA. Furthermore, transfection with Serpine1‑specific small interfering RNA attenuated the migration of ASCs. In conclusion, the present study is the first, to the best of our knowledge, to report that ROS generation and miR‑210 expression are associated with the LPA‑induced stimulation of ASCs, and that Serpine1 mediates the LPA‑induced migration of ASCs. These results further suggest that LPA may be used for ASC stimulation during stem cell expansion.

Expression of hypoxia-inducible factor-1α, endothelin-1 and adrenomedullin in newborn rats with hypoxia-induced pulmonary hypertension.

Hypoxia-inducible factor (HIF)-1α is associated with hypoxia-induced pulmonary hypertension (HPH) in adults. In the present study, the expression levels of HIF-1α, endothelin (ET)-1 and adrenomedullin (ADM) were analyzed during HPH in neonates. In total, 96 newborn rats were subjected to hypoxia or normoxia for 3, 5, 7, 10, 14 or 21 days (n=8 per subgroup). HIF-1α, ET-1 and ADM expression levels were measured by quantitative polymerase chain reaction. In addition, the intima-media thickness/external diameter ratio (MT%) and medial wall cross-sectional area/vessel total cross-sectional area ratio (MA%) were calculated to evaluate pulmonary vascular remodeling. The mean pulmonary arterial pressure (mPAP) increased with exposure to hypoxia. Furthermore, the expression levels of HIF-1α, ET-1 and ADM in the lungs were shown to increase after three and five days of hypoxia, while the MT% and MA% increased after seven days of hypoxia, as compared with the controls (P<0.05). Therefore, the expression of HIF-1α, ET-1 and ADM is upregulated in the lungs of newborn rats during early HPH. At later stages, the mPAP increases, vascular remodeling occurs and HIF-1α, ET-1 and ADM expression levels restore to normal levels.

Adrenomedullin is a therapeutic target in colorectal cancer

The KRAS oncogene influences angiogenesis, metastasis and chemoresistance in colorectal cancers (CRCs), and these processes are all enhanced in hypoxic conditions. To define functional activities of mutant KRAS in a hypoxic microenvironment, we first performed cDNA microarray experiments in isogenic DKs5 and DKO3 colon cancer cell lines that differ only by their expression of mutant KRAS (K-ras(D13)). Adrenomedullin (ADM) was identified as one of the most significantly upregulated genes in DKs5 cells that express the KRAS oncogene in hypoxia (3.2-fold, p = 1.47 × 10(-5)). Ectopic expression of mutant KRAS (K-ras(V12)) in Caco-2 cells (K-ras(WT)) induced ADM, whereas selective knockdown of mutant KRAS alleles (K-ras(D13) or K-ras(V12)) in HCT116, DLD1 and SW480 colon cancer cells suppressed the expression of ADM in hypoxia. Knockdown of ADM in colon tumor xenografts blocked angiogenesis and stimulated apoptosis, resulting in tumor suppression. Furthermore, ADM also regulated colon cancer cell invasion in vitro. Among 56 patients with CRC, significantly higher expression levels of ADM were observed in samples harboring a KRAS mutation. Collectively, ADM is a new target of oncogenic KRAS in the setting of hypoxia. This observation suggests that therapeutic targets may differ depending upon the specific tumor microenvironment.

Adrenomedullin is involved in the progression of colonic adenocarcinoma

Adrenomedullin (ADM), initially identified in human pheochromocytoma, participates in a wide range of physiological and pathological processes, including vasorelaxation, angiogenesis and apoptosis. Recent studies have reported that ADM protected tumor cells against apoptotic cell death via the upregulation of Bcl-2 or the activation of the phosphatidylinositol 3-kinase/Akt pathway. Several studies have also provided evidence that ADM is involved in tumor initiation and progression. However, this has not been shown in gastrointestinal tumors. To investigate the role of ADM in gastrointestinal tumor progression, we determined the expression levels of ADM in 72cases of stomach cancer and 84cases of colon cancer and determined whether there was an association between the ADM expression levels and pathological parameters or clinical survival rates. We found that the expression levels of ADM were significantly higher in colon cancers than in matching normal mucosal tissues. In addition, the expression levels of ADM in colon cancers were correlated with cancer stage and clinical survival rate. However, we did not find any significant correlations between ADM expression levels and clinical or pathological parameters in stomach cancers. Taken together, our data strongly suggest that ADM is involved in the progression of colon cancer.

Adrenomedullin in Ovarian Cancer: Foe In Vitro and Friend In Vivo?

Stromal elements within a tumor interact with cancer cells to create a microenvironment that supports tumor growth and survival. Adrenomedullin (ADM) is an autocrine/paracrine factor produced by both stromal cells and cancer cells to create such a microenvironment. During differentiation of macrophages, ADM is produced in response to pro-inflammatory stimuli and hypoxia. In this study we investigated the role of ADM as a growth factor for ovarian cancer cells and as a modulator of macrophages. We also analyzed ADM expression levels in a retrospective clinical study using nanofluidic technology and assessment of ADM at the gene level in 220 ovarian cancer patients. To study the effects of ADM, ovarian cancer cell lines A2780, OVCAR-3, and HEY and their drug-resistant counterparts were used for proliferation assays, while monocytes from healthy donors were differentiated in vitro. ADM was a weak growth factor, as revealed by proliferation assays and cell cycle analysis. After culturing cancer cells under stressing conditions, such as serum starvation and/or hypoxia, ADM was found to be a survival factor in HEY but not in other cell lines. In macrophages, ADM showed activity on proliferation/differentiation, primarily in type 2 macrophages (M2). Unexpectedly, the clinical study revealed that high expression of ADM was linked to positive outcome and to cancer with low Ca125. In conclusion, although in vitro ADM was a potential factor in biological aggressiveness, this possibility was not confirmed in patients. Therefore, use of an ADM antagonist would be inappropriate in managing ovarian cancer patients.

The study of the relationship between the expression of Adrenomedullin and the microvessel density in renal cell cancer

Objective To investigate the relationship between the expression of Adrenomedullin ( ADM) and the microvessel density ( MVD) in renal cell cancer( RCC) . Methods In 33 cases of RCC patients, the ADM expression was detected by immunohistochemistry and flow cytometry ( FCM) , and the MVD was also counted in the tumortissue. Results ADM was expressed in all cases of RCC (33/33,100. 0% ) ,but only 3 cases (3/33,9. 1% ) expressed in the normal nephridial tissue. The ADM expression levels in RCC (1267. 84 ± 127. 52) was higher than that in the normal nephridial tissue (970. 36 ±171. 46) P ＜0. 05. Conclusion The level of MVD was correlated to the expression of ADM. ADM is one of the regulators of the new vessels. Key words: Renal cell cancer; Adrenomedullin; Microvessel density; Immunohistochemistry; Flow cytometry

Expression of Adrenomedullin in Human Oviduct, Its Regulation by the Hormonal Cycle and Contact with Spermatozoa, And Its Effect on Ciliary Beat Frequency of the Oviductal Epithelium

Abstract Context: Adrenomedullin (ADM) has been found expressed in the mouse oviduct and might play a role in reproduction. Objective: To demonstrate the expression of adrenomedullin (ADM) in the human oviduct, investigate its regulation by steroidal hormones and spermatozoa contact, and study its effect on ciliary beat frequency (CBF) in the human oviduct. Design, Setting, Patients and Interventions: Oviducts from women undergoing hysterectomy for benign diseases in a university hospital were collected. The oviducts were treated with estradiol and/or progesterone to simulate different phases of the ovarian cycle. ADM expression was studied at the peptide and mRNA levels by immunohistochemistry and RT-PCR respectively. CBF was measured after treatment with graded concentrations of ADM and its antagonists. Cells from OE-E6/E7, an immortalized oviductal cell line, as well as oviductal tissue were co-cultured with and without direct contact with capacitated human spermatozoa to compare oviductal cell ADM expression levels. CBF was also analyzed in oviductal tissue after spermatozoa-oviduct co-incubation. Results: ADM expression was the highest in the isthmic region and in a hormonal environment simulating the early luteal phase. CBF was increased by ADM in a dose-dependent manner which was blocked by ADM and calcitonin-gene-related peptide receptor antagonists. Direct contact with spermatozoa in co-culture resulted in higher ADM expression in OE-E6/E7 cell line and oviductal tissue, and higher CBF in oviductal epithelium. Conclusions: ADM expression in the human oviduct is hormone-dependent and is up-regulated by sperm contact. ADM stimulates ciliary motility of the human oviduct.

Expression of Adrenomedullin in Human Oviduct, Its Regulation by the Hormonal Cycle and Contact with Spermatozoa, and Its Effect on Ciliary Beat Frequency of the Oviductal Epithelium

Adrenomedullin (ADM) has been found expressed in the mouse oviduct and might play a role in reproduction. The objective of the study was to demonstrate the expression of ADM in the human oviduct, investigate its regulation by steroidal hormones and spermatozoa contact, and study its effect on ciliary beat frequency (CBF) in the human oviduct. DESIGN, SETTING, PATIENTS, AND INTERVENTIONS: Oviducts from women undergoing hysterectomy for benign diseases in a university hospital were collected. The oviducts were treated with estradiol and/or progesterone to simulate different phases of the ovarian cycle. ADM expression was studied at the peptide and mRNA levels by immunohistochemistry and RT-PCR, respectively. CBF was measured after treatment with graded concentrations of ADM and its antagonists. Cells from OE-E6/E7, an immortalized oviductal cell line, as well as oviductal tissue were cocultured with and without direct contact with capacitated human spermatozoa to compare oviductal cell ADM expression levels. CBF was also analyzed in oviductal tissue after spermatozoa-oviduct coincubation. ADM expression was the highest in the isthmic region and in a hormonal environment simulating the early luteal phase. CBF was increased by ADM in a dose-dependent manner, which was blocked by ADM and calcitonin-gene-related peptide receptor antagonists. Direct contact with spermatozoa in coculture resulted in higher ADM expression in OE-E6/E7 cell line and oviductal tissue and higher CBF in oviductal epithelium. ADM expression in the human oviduct is hormone dependent and is up-regulated by sperm contact. ADM stimulates ciliary motility of the human oviduct.

Adrenomedullin and its receptor, calcitonin receptor-like receptor, are aberrantly expressed in women with idiopathic menorrhagia

The human endometrium undergoes a unique process of benign angiogenesis under the control of ovarian steroids during reproductive life. Aberrant angiogenesis has been implicated in idiopathic menorrhagia, a common gynaecological complaint. One of the key factors involved in endometrial angiogenesis is adrenomedullin (AM), a multifunctional 52-amino acid peptide. AM mediates the activities of endometrial angiogenesis via calcitonin receptor-like receptor (CLR). The objective of the present study was to compare the endometrial expression of AM and CRL in women with and without idiopathic menorrhagia. Endometrial biopsies were obtained from 9 women with menorrhagia (≥80 ml per menstruation) and 12 women with normal blood loss (<80 ml per menstruation). Protein and mRNA expression levels of AM and CLR were determined using immunohistochemistry and real-time PCR. Compared to the controls, patients with menorrhagia exhibited low immunostaining intensity of AM, while high CLR staining was observed in the epithelium (p<0.05). No difference in mRNA expression was observed between the groups. These data suggest that an imbalance in the AM/CLR system might alter endometrial angiogenesis in menorrhagia.

Changes and Distributions of Peptides Derived From Proadrenomedullin in Left-to-Right Shunt Pulmonary Hypertension of Rats

Pulmonary hypertension (PHT) is a common complication of congenital heart disease and the pulmonary vascular structural remodeling because of the high pulmonary blood flow is considered to be the key pathologic process. In the present study the change and distribution of peptides derived from proadrenomedullin in a rat model of PHT caused by a left-to-right shunt were measured to elucidate the mechanism. Twelve weeks after a cervical shunt was established by a cuff technique in an experimental group of rats, the systolic pulmonary artery pressure (sPAP) was measured by catheterization. Morphologic assessment included the measurement of the weight ratio of the right ventricle (RV) to the left ventricle plus septum (LV+SP) and the mean percentage of media wall thickness (MT%) in moderate-sized pulmonary arteries. The distribution of adrenomedullin (ADM), adrenotensin (ADT) and proadrenomedullin N-terminal 20 peptide (PAMP) were measured by immunohistochemical staining. The mRNA expressions of ADM, ADT, PAMP and proADM45-92 were investigated by reverse transcription polymerase chain reaction. The sPAP and the ratios of RV/(LV+SP) and MT% were significantly increased in the experimental rats (p<0.01, and p<0.05). Positive signals (brown granules) of ADM, ADT and PAMP were mainly located in the smooth muscle cells, but the brown granules of PAMP were also located in the tunica adventitia. The levels of ADM and PAMP were significantly increased, while that of ADT was markedly decreased in the Experimental group compared with the Control group (p<0.05 and p<0.01 respectively). The mRNA expression levels of ADM and preADM45-92 were significantly increased in the experimental rats (p<0.01); however, the expression of ADT mRNA was statistically deceased in the Experimental group compared with the Control group (p<0.01). The mRNA expression of PAMP showed no statistical difference between the 2 groups of rats (p>0.05). The change and distribution of peptides derived from proadrenomedullin in PHT caused by a left-to-right shunt in rats is powerful evidence for intramolecular regulation.

Participation of adrenomedullin and its relation with vascular endothelial growth factor in androgen regulation of prostatic blood flow in vivo

Objectives We had previously reported that androgen-regulated prostatic blood flow and vascular endothelial growth factor (VEGF) were involved in the signal transduction pathway. Adrenomedullin (ADM) is a multifunctional regulatory peptide with mitogenic and angiogenic capabilities that are regulated by androgen. ADM is abundantly expressed in the prostate. We focused on ADM and evaluated its participation and relation with VEGF in androgen prostatic blood flow regulation using a castrated rat model. Methods We examined the effect of locally injected dihydrotestosterone (DHT) and ADM, and the co-administration of DHT with an ADM receptor antagonist (ADM 22-52) on prostatic blood flow. Furthermore, prostatic blood flow was evaluated after ADM and VEGF administration with each other’s antagonist, VEGF neutralizing antibody and ADM 22-52, respectively. Changes in the mRNA expression levels of ADM in the prostate after castration and successive androgen stimulation were also evaluated. Results The administration of ADM promptly increased prostatic blood flow in a dose-dependent manner within 30 minutes. The DHT-induced increase in prostatic blood flow was completely abolished by co-administration with anti-ADM. Anti-ADM inhibited the VEGF-induced prostatic blood flow elevation, but a VEGF neutralizing antibody did not affect the ADM-mediated blood flow elevation. Furthermore, upregulation of the ADM gene induced by DHT was inhibited by co-administration with a VEGF-neutralizing antibody. Conclusions These results have clearly demonstrated the direct regulation of prostatic blood flow by ADM and its involvement in androgenic prostatic blood flow regulation. Furthermore, ADM was estimated to be a downstream mediator of VEGF action in the signal transduction pathway.

Adrenomedullin in Hypertension

Adrenomedullin (AM) is a potent vasodilatory peptide originally discovered in human pheochromocytoma tissue. The gene expression of AM is widely distributed in the cardiovascular system and many physiological actions of AM on cardiovascular system have been reported. Previous studies demonstrated that the plasma AM level is increased in patients with hypertension and further increased in patients with organ damage. We and other groups recently showed that two molecular forms of AM, AM-glycine, an inactive form, and AM-mature, an active form, circulate in human plasma and that the major molecular form in plasma is AM-glycine. Recent studies using AM antagonist or AM knockout mice confirmed the role of AM in the regulation of blood pressure. Indeed, administration of AM is beneficial in patients with hypertension, renal disease, and heart failure. In addition, recent studies revealed that AM and its receptor components such as calcitonin receptor like receptor (CRLR), receptor activity modifying protein (RAMP) 2, and RAMP3 are colocalized in peripheral tissues, including the heart, kidney, and vasculature, suggesting a role of AM as a regulator of local function. In fact, tissue AM levels and the gene expression levels of AM and its receptor are altered in hypertension. We recently showed that cardiac tissue AM levels and the gene expression levels of AM, CRLR, RAMP2, and RAMP3 are increased in left ventricular hypertrophy and further increased in hypertensive heart failure. These findings imply that increased expression of the AM system including the ligand and receptor components may modulate the pathophysiology in hypertension via the effects of AM not only as a circulating factor, but also as a local regulator. This review describes the structure, structure-activity relationships, tissue distribution, receptors, physiological action, and circulating levels of AM and also discusses what is known about the pathophysiological role of AM in hypertension. Keywords: vasodilatory peptide, pheochromocytoma, blood vessels, cardiovascular disease, carboxypeptidase, calcitonin generelated peptide (cgrp), receptor activity modifying protein (ramp)

Altered gene expression of adrenomedullin and its receptor system and molecular forms of tissue adrenomedullin in left ventricular hypertrophy induced by malignant hypertension

To investigate the pathophysiological role of adrenomedullin (AM) in left ventricular hypertrophy (LVH) in hypertension, we measured the plasma level, left ventricle (LV) tissue level, and mRNA abundance of AM and the mRNA abundance of the AM receptor system in the LV. We also analyzed the molecular forms of AM in the plasma and LV tissue and investigated the relationships between AM and the degree of LVH. We studied the following three groups: control Wistar Kyoto rats (WKY), control spontaneously hypertensive rats (SHR), and deoxycorticosterone acetate (DOCA)-salt SHR (D-SHR). We measured AM-mature, active form, and AM-total (active form+inactive form) in plasma and the LV by a newly developed immunoradiometric assay. Gene expression of AM was measured by Northern blot analysis and gene expression of AM receptor system components, such as calcitonin receptor-like receptor (CRLR), receptor activity modifying protein 2 (RAMP2), and RAMP3 was measured by the reverse transcription polymerase chain reaction method. After 3 weeks of DOCA treatment, D-SHR was characterized by higher blood pressure, LV weight, and plasma atrial natriuretic peptide levels compared with those in the other two groups. Plasma AM-mature and AM-total levels were significantly higher in D-SHR than in the other two groups, whereas there were no significant differences in the AM-mature/AM-total ratio among the three groups. On the other hand, LV tissue AM-mature and AM-total levels were also significantly higher in D-SHR than in the other two groups, and the AM-mature/AM-total ratio was significantly higher in LV tissues than in plasma. Furthermore, the LV tissue AM-mature/AM-total ratio was significantly higher in D-SHR compared with the other two groups. The LV tissue AM-mature/AM-total ratio was significantly correlated with LV weight/body weight ( r=0.92, p<0.001). The gene expression levels of AM, CRLR, RAMP2, and RAMP3 in the LV were significantly higher in D-SHR than in the other two groups. These results suggest that the AM amidating enzyme activity, ligand, and receptor system are all upregulated in the LV hypertrophy in this malignant hypertensive rat model. Considering that AM serves as a local antihypertrophic autocrine and/or paracrine factor, the induction of AM system observed here may modulate the pathophysiology of LV hypertrophy in certain forms of malignant hypertension.