Intermedin(IMD)or adrenomedullin 2 is a novel peptide related to the calcitonin gene-related peptide(CGRP)family.Via calcitonin receptor-like receptor/receptor activity modifying proteins,the common receptor complexes...Intermedin(IMD)or adrenomedullin 2 is a novel peptide related to the calcitonin gene-related peptide(CGRP)family.Via calcitonin receptor-like receptor/receptor activity modifying proteins,the common receptor complexes of CGRP,IMD exerts a wide range of biological effects,especially regulation of cardiovascular homeostasis.Proteolytic processing of a larger IMD precursor yields a series of biologically active C-terminal fragments,IMD1–53,IMD1–47 and IMD8–47.IMD and its receptors are present in the cardiovascular system,and IMD is present at low levels in plasma.In the cardiovascular system,IMD has multiple functions such as regulation of blood pressure and cardiac function,pro-angiogenesis,endothelial barrier function protection,anti-oxidative stress,and anti-endoplasmic reticulum stress.IMD participates widely in the pathogenesis of atherosclerosis,hypertension,pulmonary arterial hypertension and vascular calcification.It is a vascular regulatory factor of homeostasis and a vital endogenous protective factor against vascular diseases.展开更多
Intermedin/adrenomedullin-2(IMD/AM2), a member of the calcitonin gene-related peptide/AM family,plays an important role in protecting the cardiovascular system. However, its role in the enhanced sympathoexcitation in ...Intermedin/adrenomedullin-2(IMD/AM2), a member of the calcitonin gene-related peptide/AM family,plays an important role in protecting the cardiovascular system. However, its role in the enhanced sympathoexcitation in obesity-related hypertension is unknown. In this study, we investigated the effects of IMD in the paraventricular nucleus(PVN) of the hypothalamus on sympathetic nerve activity(SNA), and lipopolysaccharide(LPS)-induced sympathetic activation in obesity-related hypertensive(OH)rats induced by a high-fat diet for 12 weeks. Acute experiments were performed under anesthesia. The dynamic alterations of sympathetic outflow were evaluated as changes in renal SNA and mean arterial pressure(MAP) in response to specific drugs. Male rats were fed a control diet(12% kcal as fat) or a high-fat diet(42% kcal as fat) for 12 weeks to induce OH. The results showed that IMD protein in the PVN was downregulated, but Toll-like receptor 4(TLR4) and plasma norepinephrine(NE, indicating sympathetic hyperactivity) levels, and systolic blood pressure were increased in OH rats. LPS(0.5 lg/50 nL)-induced enhancement of renal SNA and MAP was greater in OH rats than in obese or control rats. Bilateral PVN microinjection of IMD(50 pmol)caused greater decreases in renal SNA and MAP in OH rats than in control rats, and inhibited LPS-induced sympatheticactivation, and these were effectively prevented in OH rats by pretreatment with the AM receptor antagonist AM22-52.The mitogen-activated protein kinase/extracellular signalregulated kinase(ERK) inhibitor U0126 in the PVN partially reversed the LPS-induced enhancement of SNA. However,IMD in the PVN decreased the LPS-induced ERK activation,which was also effectively prevented by AM22-52. Chronic IMD administration resulted in significant reductions in the plasma NE level and blood pressure in OH rats. Moreover,IMD lowered the TLR4 protein expression and ERK activation in the PVN, and decreased the LPS-induced sympathetic overactivity. These results indicate that IMD in the PVN attenuat展开更多
Objective To examine the effects of exogenously administered intermedin （IMD,adrenomedullin-2） on arterial blood pressure,cardiac function and the cardiovascular IMD receptor system in spontaneously hypertensive ra...Objective To examine the effects of exogenously administered intermedin （IMD,adrenomedullin-2） on arterial blood pressure,cardiac function and the cardiovascular IMD receptor system in spontaneously hypertensive rats （SHRs） as well as to investigate the associated mechanisms.Methods Thirteen week-old male rats were divided in Wistar Kyoto （WKY） group （n =12）,SHR group （n =12）,IMD group （SHRs infused with IMD 1-47 500 ng/kg per hour,n =12）,and ADM group （SHRs infused with adrenomedullin 500 ng/kg per hour,n =12）.Results A two-week continuous administration of low dose IMD 1-47 via mini-osmotic pumps markedly reduced blood pressure,the maximal rates of increase and decrease of left-ventricle pressure development （LV ± dp/dtmax）,left ventricular systolic pressure and heart rate in SHRs.Furthermore,IMD also inhibited protein over-expression of cardiovascular IMD receptors,myocardial Receptor Activity-Modifying Proteins （RAMP1 and RAMP2）,aortic RAMP1,RAMP2,RAMP3,and calcitonin receptor-like receptor （CRLR）;suppressed up-regulation of aortic RAMP1,RAMP2,RAMP3 and CRLR gene expression; and markedly elevated the mRNA abundance of myocardial atrial natriuretic peptide （ANP） and myocardial brain natriuretic peptide （BNP）.Additionally,IMD 1-47 administration in SHRs increased aortic cAMP concentration and reduced myocardial cAMP concentration.Conclusion These findings support the speculation that IMD,as a cardiovascular active peptide,is involved in blood pressure reduction and cardiac function amelioration during hypertension.The mechanism underlying this effect may involve IMD binding of a receptor complex formed by RAMPs and CRLR,and consequential regulation of cAMP levels and other cardiovascular active factors,such as ANP and BNP.展开更多
基金supported by the National Natural Science Foundation of China(91339203,81270407,81170082 to Qi YongFen)
文摘Intermedin(IMD)or adrenomedullin 2 is a novel peptide related to the calcitonin gene-related peptide(CGRP)family.Via calcitonin receptor-like receptor/receptor activity modifying proteins,the common receptor complexes of CGRP,IMD exerts a wide range of biological effects,especially regulation of cardiovascular homeostasis.Proteolytic processing of a larger IMD precursor yields a series of biologically active C-terminal fragments,IMD1–53,IMD1–47 and IMD8–47.IMD and its receptors are present in the cardiovascular system,and IMD is present at low levels in plasma.In the cardiovascular system,IMD has multiple functions such as regulation of blood pressure and cardiac function,pro-angiogenesis,endothelial barrier function protection,anti-oxidative stress,and anti-endoplasmic reticulum stress.IMD participates widely in the pathogenesis of atherosclerosis,hypertension,pulmonary arterial hypertension and vascular calcification.It is a vascular regulatory factor of homeostasis and a vital endogenous protective factor against vascular diseases.
基金supported by the National Natural Science Foundation of China(81000106 and81470539)
文摘Intermedin/adrenomedullin-2(IMD/AM2), a member of the calcitonin gene-related peptide/AM family,plays an important role in protecting the cardiovascular system. However, its role in the enhanced sympathoexcitation in obesity-related hypertension is unknown. In this study, we investigated the effects of IMD in the paraventricular nucleus(PVN) of the hypothalamus on sympathetic nerve activity(SNA), and lipopolysaccharide(LPS)-induced sympathetic activation in obesity-related hypertensive(OH)rats induced by a high-fat diet for 12 weeks. Acute experiments were performed under anesthesia. The dynamic alterations of sympathetic outflow were evaluated as changes in renal SNA and mean arterial pressure(MAP) in response to specific drugs. Male rats were fed a control diet(12% kcal as fat) or a high-fat diet(42% kcal as fat) for 12 weeks to induce OH. The results showed that IMD protein in the PVN was downregulated, but Toll-like receptor 4(TLR4) and plasma norepinephrine(NE, indicating sympathetic hyperactivity) levels, and systolic blood pressure were increased in OH rats. LPS(0.5 lg/50 nL)-induced enhancement of renal SNA and MAP was greater in OH rats than in obese or control rats. Bilateral PVN microinjection of IMD(50 pmol)caused greater decreases in renal SNA and MAP in OH rats than in control rats, and inhibited LPS-induced sympatheticactivation, and these were effectively prevented in OH rats by pretreatment with the AM receptor antagonist AM22-52.The mitogen-activated protein kinase/extracellular signalregulated kinase(ERK) inhibitor U0126 in the PVN partially reversed the LPS-induced enhancement of SNA. However,IMD in the PVN decreased the LPS-induced ERK activation,which was also effectively prevented by AM22-52. Chronic IMD administration resulted in significant reductions in the plasma NE level and blood pressure in OH rats. Moreover,IMD lowered the TLR4 protein expression and ERK activation in the PVN, and decreased the LPS-induced sympathetic overactivity. These results indicate that IMD in the PVN attenuat
文摘Objective To examine the effects of exogenously administered intermedin （IMD,adrenomedullin-2） on arterial blood pressure,cardiac function and the cardiovascular IMD receptor system in spontaneously hypertensive rats （SHRs） as well as to investigate the associated mechanisms.Methods Thirteen week-old male rats were divided in Wistar Kyoto （WKY） group （n =12）,SHR group （n =12）,IMD group （SHRs infused with IMD 1-47 500 ng/kg per hour,n =12）,and ADM group （SHRs infused with adrenomedullin 500 ng/kg per hour,n =12）.Results A two-week continuous administration of low dose IMD 1-47 via mini-osmotic pumps markedly reduced blood pressure,the maximal rates of increase and decrease of left-ventricle pressure development （LV ± dp/dtmax）,left ventricular systolic pressure and heart rate in SHRs.Furthermore,IMD also inhibited protein over-expression of cardiovascular IMD receptors,myocardial Receptor Activity-Modifying Proteins （RAMP1 and RAMP2）,aortic RAMP1,RAMP2,RAMP3,and calcitonin receptor-like receptor （CRLR）;suppressed up-regulation of aortic RAMP1,RAMP2,RAMP3 and CRLR gene expression; and markedly elevated the mRNA abundance of myocardial atrial natriuretic peptide （ANP） and myocardial brain natriuretic peptide （BNP）.Additionally,IMD 1-47 administration in SHRs increased aortic cAMP concentration and reduced myocardial cAMP concentration.Conclusion These findings support the speculation that IMD,as a cardiovascular active peptide,is involved in blood pressure reduction and cardiac function amelioration during hypertension.The mechanism underlying this effect may involve IMD binding of a receptor complex formed by RAMPs and CRLR,and consequential regulation of cAMP levels and other cardiovascular active factors,such as ANP and BNP.
