Angiotensin-converting Enzyme mRNA Expression Research Articles

Angiotensin‐Converting Enzyme Inhibition and Angiotensin AT1 Receptor Blockade Downregulate Angiotensin‐Converting Enzyme Expression and Attenuate Renal Injury in Streptozotocin‐Induced Diabetic Rats

Angiotensin-converting enzyme (ACE) is upregulated in the diabetic kidney and contributes to renal injury. This study investigates the possible beneficial effects of the ACE inhibitor (ACEI), enalapril and the AT1 receptor blocker (ARB), valsartan, on renal ACE expression, renal structure, and function in streptozotocin (STZ)-induced diabetic rats. Male Wistar rats were allocated into four groups: control, STZ-diabetic rats, and STZ-diabetic rats treated with either enalapril (10 mg/kg/day) or valsartan (50 mg/kg/day) for 8 weeks. Enalapril and valsartan reduced renal ACE mRNA and protein expression, Na(+) /K(+) -ATPase activity, oxidative stress, and serum transforming growth factor-β1 levels compared to the diabetic group. Both treatments normalized renal nitrate/nitrite levels and ameliorated the observed histopathological changes. In conclusion, ACE downregulation by ACEI and ARB indicates that angiotensin II upregulates ACE through AT1 receptor. Prevention of diabetes-induced changes in ACE expression and Na(+) /K(+) -ATPase activity could be a new explanation of the renoprotective effects of ACEIs and ARBs.

Effects of rosuvastatin on expression of angiotensin-converting enzyme 2 after vascular balloon injury in rats.

ObjectiveTo investigate the effects and mechanisms of rosuvastatin on angiotensin -converting enzyme 2 (ACE2) in the process of neointimal formation after vascular balloon injury in rats, and to explore the effects of ACE2 and rosuvastatin in restenosis.MethodsThirty-six Wistar rats were randomly allocated into three groups: control group (n = 12), surgery group (n = 12), and statin group (n = 12). Aortic endothelial denudation of rats was performed using 2F balloon catheters. At days 14 and 28 after injury, aortic arteries were harvested to examine the following. Intimal thickening was examined by hematoxylin and eosin staining. We measured angiotensin II (Ang II) and angiotensin 1-7 (Ang-[1–7]) levels by a radioimmunological method or enzyme-linked immunosorbent assay. Protein and mRNA expression of ACE2 and Ang II type 1 receptor (AT1) were investigated by immunohistochemistry, Western blots, and Reverse transcriptase-polymerase chain reaction (RT-PCR). We measured changes in proliferating cell nuclear antigen (PCNA) by immunohistochemistry. The level of phosphorylated extracellular signal regulated kinase 1/2 (P-ERK1/2) was evaluated by Western blotting.ResultsProliferation of vascular smooth muscle cells (VSMC) and intimal thickening were higher at day 14 after vascular balloon injury in the surgery group compared with the control group. Proliferation of VSMC was decreased by day 28 after injury, while intimal thickening continued. With rosuvastatin treatment, the extent of VSMC proliferation and intimal thickening was reduced at day 14 and 28 after injury. Ang II and P-ERK levels were significantly increased, Ang-(1–7) levels were significantly decreased, mRNA and protein expressions of ACE2 were significantly decreased, and AT1 expression was significantly increased at days 14 and 28 after vascular balloon injury in the surgery group compared with the control group. PCNA expression was higher in the surgery group than in the control group, and it was significantly decreased after being given rosuvastatin. Expression of ACE2 mRNA and protein, and Ang-(1–7) levels were significantly increased, while AT1 expression and levels of Ang II and P-ERK were significantly decreased in the statin group compared with the surgery group.ConclusionsExpression of ACE2 mRNA and protein is decreased in the process of intimal thickening after balloon injury. The inhibitory effect of rosuvastatin on intimal thickening is related to upregulation of ACE2, an increase in Ang-(1–7), downregulation of AT1, and activation of the P-ERK pathway.

Do RAS Inhibitors Protect the Brain from Cerebral Ischemic Injury?

In addition to centrally regulating electrolyte homeostasis and blood pressure, angiotensin IIhas various general effects on the central nervous system. The existence of renin-angiotensin system components in the brain has been well established. Angiotensin II and other renin-angiotensin system components are synthesized and distributed throughout the brain. Post-ischemic oral administration of a non-hypotensive dose (1/10th of the clinical dose) of angiotensin receptor blocker (ARB) has protective effects on reducing cerebral ischemic injury and improving neurological outcomes. Brain tissue angiotensin II levels transiently increase after reperfusion through the local generation of angiotensin IIand not via the transudation of plasma angiotensin II. Systemic administration of ARBs decreases brain tissue angiotensin II in both the intact and ischemic brain tissue via downregulation of angiotensinogen and angiotensin-converting enzyme mRNA expression, although plasma ARB barely crosses the blood-brain barrier during systemic ARB treatment. Only hypotensive dose of ARB treatment opens leptomeningeal anastomoses. Therefore, systemic ARB treatment shows neuroprotective effects not through increasing collateral perfusion but decreasing brain tissue angiotensin II in a nonhypotensive dose.

ACE2 deficiency induced perivascular fibrosis and cardiac hypertrophy during postnatal development in mice

In order to investigate the role of angiotensin-converting enzyme 2 (ACE2) in cardiac development, we examined the effects of ACE2 deficiency on postnatal development of the heart using ACE2-knockout (ACE2KO) mice. Heart samples of wild type (WT; C57BL/6J) mice and ACE2KO mice were taken at 1, 4, and 10 weeks of age. In WT mice, expression of ACE2 mRNA increased from 1 week to 10 weeks. A similar increase was observed in immunostaining of ACE2 in the heart, in which ACE2 was strongly expressed in coronary arteries. Compared with WT mice, heart weight was greater in ACE2KO mice at 4 weeks, and coronary artery thickening and perivascular fibrosis were also already enhanced from 4 weeks. Consistent with the increase of fibrosis, cardiac expression of collagen and TIMP was higher, and expression of MMP was lower in ACE2KO mice at 4 weeks. In addition, TGF-β mRNA was also higher, and lower expression of PPARγ mRNA was observed at 4 weeks in ACE2KO mice. These results suggest that ACE2 plays an important role in postnatal development of the heart, and that lack of ACE2 enhances coronary artery remodeling with an increase in perivascular fibrosis and cardiac hypertrophy already around the weaning period.

Effects of enalapril on the expression of cardiac angiotensin-converting enzyme and angiotensin-converting enzyme 2 in spontaneously hypertensive rats

The discovery of angiotensin-converting enzyme 2 (ACE2) has greatly modified understanding of the renin-angiotensin system (RAS). To investigate the cardiac expression of ACE2 and ACE in spontaneously hypertensive rats (SHRs) and the effects of enalapril on them. Fifteen SHRs were randomly assigned to two groups: an SHR control group (n=7), treated with vehicle; and an enalapril group (n=8), treated with enalapril (15 mg/kg/day). After 4 weeks of treatment, the rats were killed and the left ventricular tissue was dissected. Reverse transcription-polymerase chain reaction and Western blot protein staining were performed to detect expression of ACE2 and ACE messenger ribonucleic acid (mRNA) and protein. Ten Wistar Kyoto rats (WKYs) served as the normotensive control group, which were treated with vehicle. Compared with in normotensive WKYs, cardiac expression of ACE mRNA and protein in SHRs was increased (1.68±0.34 vs. 0.33±0.12, P<0.05 and 1.21±0.14 vs. 0.71±0.11, P<0.05, respectively), whereas cardiac expression of ACE2 mRNA and protein was decreased (0.50±0.15 vs. 1.16±0.24, P<0.05 and 0.71±0.24 vs. 1.22±0.14, P<0.05, respectively). After treatment with enalapril, the levels of ACE mRNA and protein were decreased (0.44±0.19 vs. 1.68±0.34, P<0.01 and 0.87±0.13 vs. 1.21±0.14, P<0.05, respectively), the level of ACE2 mRNA was increased (1.77±0.49 vs. 0.50±0.15, P<0.05) but the level of ACE2 protein remained unchanged. In SHRs, the expression of cardiac ACE was remarkably increased, whereas ACE2 was notably decreased. Reduction of ACE and elevation of ACE2 might be one of the mechanisms underlying the antihypertensive function of enalapril.

Effects of sevoflurane preconditioning on expression of angiotensin converting enzyme mRNA in lung tissues during lung ischemia-reperfusion in rats

Objective To investigate the effects of sevoflurane preconditioning on the expression of pulmonary angiotensin converting enzyme (ACE) mRNA in lung tissues during lung ischemia-reperfusion (I/R) in rats.Methods Fifty-four male Sprague-Dawley rats,weighing 250-320 g,were randomly divided into 3 groups (n =18 each):sham operation group (group S),I/R group and sevoflurane preconditioning group (group SP).The animals were anesthetized,tracheostomized and mechanically ventilated.Lung I/R was induced by clamping the left pulmonary hilum for 45 min followed by 120 min reperfusion in groups I/R and SP.While the left pulmonary hilum was only isolated but not ligated in group S.2.1％ sevoflurane was inhaled for 30 min,and lung I/R was induced 10 min after the end of inhalation in group SP.Six rats in each group were chosen at 30,60 and 120 min of reperfusion and sacrificed,lungs were removed for determination of wet/dry lung weight (W/D) ratio,MPO activity (by colorimetric method) and the expression of ACE mRNA (by RT-PCR) and for microscopic examination in lung tissues.Results Compared with group S,the W/D ratio,MPO activity and expression of ACE mRNA were significantly increased in groups I/R and SP (P ＜ 0.05).Compared with group I/R,the W/D ratio,MPO activity and expression of ACE mRNA were significantly decreased in group SP (P ＜ 0.05).Microscopic examination showed that the pathologic changes were significantly attenuated in group SP compared with group I/R.Conclusion Sevoflurane preconditioning can reduce lung I/R injury through downing-regulating the expression of ACE mRNA in rats. Key words: Anesthetics, inhalation; Reperfusion injury ; Lung ; Peptidyl-dipeptidase A ; Ischemic preconditioning

The Role of Angiotensin II on Sodium Appetite After a Low‐Sodium Diet

The present study aimed to investigate the role of angiotensin II (AngII) on sodium appetite in rats subjected to a normal or a low-sodium diet (1% or >0.1% NaCl) for 4days. During sodium restriction, a reduction in water intake, urinary volume and sodium excretion was observed. After a low-sodium diet, we observed decreased plasma protein concentrations and haematocrit associated with a slight reduction in arterial pressure, without any significant changes in heart rate, natraemia, corticotrophin-releasing hormone mRNA expression in the paraventricular nucleus and corticosterone levels. After providing hypertonic saline, there was an increase in saline intake followed by a small increase in water intake, resulting in an enhanced saline intake ratio and the recovery of arterial pressure. Sodium deprivation increased plasma but not brain Ang I and II concentrations. A low-sodium diet increased kidney renin and liver angiotensinogen mRNA levels but not lung angiotensin-converting enzyme mRNA expression. Moreover, Ang II type 1a receptor mRNA expression was increased in the subfornical organ and the dorsal raphe nucleus and decreased in the medial preoptic nuclei, without changes in the paraventricular nucleus and the nucleus of solitary tract after a low-sodium diet. Blockade of AT(1) receptors or brain Ang II synthesis led to a reduction in sodium intake after a low-sodium diet. Intracerebroventricular injection of Ang II led to a similar increase in sodium and water intake in the control and low-sodium diet groups. In conclusion, the results of the present study suggest that Ang II is involved in the increased sodium appetite after a low-sodium diet.

Effect of oxymatrine, the active component from Radix Sophorae flavescentis (Kushen), on ventricular remodeling in spontaneously hypertensive rats

PurposeTo examine the effects of oxymatrine (OMT) on ventricular remodeling in spontaneous hypertension rat (SHR) and the underlying mechanism. MethodsSHRs were divided into four groups: SHR control, SHR+40mg/kg captopril, SHR+30mg/kg OMT and SHR+60mg/kg OMT. Normotensive age-matched WKY rats were assigned to two groups: WKY control, WKY+30mg/kg OMT. The rats were orally administered with the corresponding drugs or drinking water for 21 weeks. Mean arterial blood pressure (MAP) and heart rate (HR) were measured. The left ventricular weight index (LVWI) and heart weight index (HWI) were determined. Myocardium tissue was stained with picric acid/Sirius red for measurement of collagen content measurements. The concentrations of serum norepinephrine and angiotensin II (Ang II) in myocardium were determined. Real-time RT-PCR was used to detect the mRNA expressions of transforming growth factor-β1 (TGF-β1), collagen types I, III and angiotensin converting enzyme (ACE). Western blots were performed to determine bioactivities of extracellular signal regulated kinase (ERK1/2), c-Jun N-terminal kinase (JNK/SAPK), p38 mitogen-activated protein kinases (p38 MAPK) and phospho-specific protein kinase C (PKC). ResultsIn the SHR, hypertension, myocardium hypertrophy, more cardiac fibrosis, higher concentrations of serum norepinephrine and myocardium Ang II were observed. OMT treatment lowered the blood pressure, reduced the concentrations of serum norepinephrine and myocardium Ang II, favorably decreased the measured gravimetric parameters, decreased the interstitial and perivascular collagen deposition, attenuated the collagen of type I and III accumulation, downregulated the mRNA expression of ACE and TGF-β1, and suppressed the phosphorylation of ERK 1/2, JNK and p38 MAPK in SHRs. ConclusionOMT prevents ventricular remodeling in SHR. The mechanisms may be related to inhibiting the gene overexpression of ACE and TGF-β1, suppressing the activation of signaling pathways of ERK 1/2, JNK and p38 MAPK.

Effects of remifentanil on lung ischemia-reperfusion injury and expression of angiotensin-converting enzyme mRNA in rats

Objective To investigate the effects of remifentanil on lung ischemia-reperfusion (I/R) injury and expression of angiotensin-converting enzyme (ACE) mRNA in rats.Methods Forty pathogen-free adult male Sprague-Dawley rats,weighing 300-350 g,were randomly divided into 5 groups (n =8 each):sham operation group (group S),group I/R and different doses of remifentanil groups (groups R1-R3).Lung I/R was produced by occlusion of the left hilum of lung for 45 min followed by 120 min reperfusion.Remifentanil was infused intravenously at a rate of 0.2,0.6 and 1.2 μg·kg-1 ·min-1 until 120 min of reperfusion after a loading dose of 1 μg/kg at 15 min before occlusion of the left hilum of lung in groups R1,R2 and R3,respectively.The equal volume of normal saline was given in groups S and I/R.The rats were scarified at 120 min of reperfusion and lungs were removed for microscopic examination and determination of wet/dry lung weight ratio (W/D ratio) and the expression of ACE mRNA (by RT-PCR) in the lung tissue.The pathological changes of the lung were scored.Results Compared with group S,the pathological score and W/D ratio were significantly increased and the expression of ACE mRNA was up-regulated in groups I/R,R1 and R2,and the pathological score was significantly increased (P ＜ 0.05),and no significant change was found in W/D ratio and the expression of ACE mRNA in group R3 (P ＞ 0.05).Compared with group I/R,the pathological score and W/D ratio were significantly decreased and the expression of ACE mRNA was down-regulated in groups R2 and R3,and the pathological score and W/D ratio were significantly decreased (P ＜ 0.05) and no significant change was found in the expression of ACE mRNA in group R1 (P ＞0.05).Compared with group R1,the pathological score and W/D ratio were significantly decreased and the expression of ACE mRNA was down-regulated in group R3,and the pathological score and W/D ratio were significantly decreased (P ＜ 0.05) and no significant change was found in the expression of ACE mRNA in group R2 (P ＞ 0.05).The pathological score,W/D ratio and expression of ACE mRNA were significantly lower in groups R3 than in group R2 (P ＜ 0.05).The pathological changes of the lung were significantly reduced in groups R1-R3 as compared with group I/R.Conclusion Remifentanil can attenuate lung I/R injury in rats in a dose-dependent manner and down-regulation of ACE mRNA expression may be involved in the mechanism. Key words: Piperidines; Reperfusion injury; Lung; Peptidyl-dipeptidase A

Association of all-trans retinoic acid treatment with the renin-angiotensin aldosterone system expression in glomerulosclerosis rats

All-trans retinoic acid (ATRA), a promising therapeutic agent, has been confirmed in animal experiments as playing a protective role against renal diseases. The renin-angiotensin aldosterone system (RAAS) plays a key role in the pathogenesis of renal diseases, and RAAS inhibitors can prevent the progression of kidney diseases. In our previous study, we found that ATRA could play a protective role against glomerulosclerosis (GS) lesions in rats, and its effect was similar to RAAS inhibitors. However, whether ATRA treatment was associated with RAAS expression was not clear. Six-week-old male Wistar rats were divided into three groups: sham operation group (SHO), glomerulosclerosis model group without treatment (GS) and GS model group treated with ATRA (GA). At the end of 13 weeks, the relevant samples were collected and analyzed. The mRNA and protein expression of angiotensin-converting enzyme 1 (ACE1) in the GS group was notably higher when compared with the SHO group. However, mRNA and protein expression of ACE1 in the ATRA treatment group was markedly down-regulated when compared with the GS group. Angiotensin-converting enzyme 2 (ACE2) expression (mRNA or protein) in the GS group was reduced compared with that in the SHO group, and ATRA markedly increased the mRNA and protein expression of ACE2 compared with the GS group. The levels of protein expression of angiotensin I and angiotensin II were significantly up-regulated in the GS group compared with those in the SHO group, and ATRA reduced their expression in the GA group when compared with the GS group. ATRA is associated with RAAS expression in GS rats, but its detailed mechanism needs to be elucidated by further research.

Abstract 441: Central Infusion of Angiotensin(1-7) Attenuates Aldosterone/Salt-Induced Increases in Blood Pressure in Ovariectomized Female Rats

In comparison to male rodents, females are protected against angiotensin II (ANG II)- and aldosterone (Aldo)-induced hypertension. However, the mechanism underlying this protective effect is not well understood. ANG(1-7) is formed from ANG II by angiotensin converting enzyme 2 (ACE2) and plays an anti-hypertensive effect in the CNS. Recent studies from our laboratory demonstrate that central blockade ANG(1-7) augments Aldo-induced hypertension in intact female rats. The present study further determined whether central infusion of ANG(1-7) will attenuate Aldo/salt-induced increase in blood pressure (BP) in ovariectomized (OVX) female rats. Systemic infusion of Aldo (0.75 μg/h, 4 weeks) into OVX female rats with 1% salt as their sole drinking fluid resulted in a significant increase in BP (Δ26.9±2.9 mmHg). Central infusion of ANG(1-7) significantly attenuated this Aldo/salt pressor effect (Δ11.9±2.8 mmHg). RT-PCR analysis revealed that mRNA expression of renin (from 3.6 to1.1-fold) and ACE1 (from 2.6 to 0.9-fold) were significantly reduced in Aldo/salt treated rats with central infusion of ANG(1-7) when compared with central vehicle infusion. In contrast, mRNA expression of ACE2 (from 1.0 to 1.4-fold), AT 2 R (from 0.4 to 1.2-fold) and estrogen receptor alpha (ERα, from 0.9 to 1.7-fold) were significantly increased in the lamina terminalis. Taken together these results suggest that a central antihypertensive arm of the brain renin-angiotensin system (ACE2/ANG(1-7)/Mas) may play an important compensatory role in the development of Aldo/salt induced hypertension in females. (HL-14388, HL-98207, DK-66086, and MH-80241)

Antenatal maternal protein deprivation: sexually dimorphic programming of the pancreatic renin-angiotensin system

As an underlying mechanism of antenatal maternal malnutrition-induced type 2 diabetes mellitus (T2DM), alterations in the local pancreatic renin-angiotensin system (RAS) may play a significant role. We tested the hypothesis that antenatal maternal protein deprivation (AMPD) leads to increased activity of the local pancreatic RAS, with associated hyperglycemia in the adult progeny. Mice dams were fed either control or 50% protein restricted diet (AMPD) starting one week before conception and maintained during complete gestation. Our results demonstrate low birth weight (control 1.5 ± 0.03 and AMPD 1.3 ± 0.03) and sexually dimorphic programming of the pancreatic RAS, with development of hyperglycemia only in the female mice offspring as a consequence of AMPD. No significant difference in serum insulin concentration was observed; however, AMPD was associated with increased mRNA and protein expression of angiotensinogen, renin and angiotensin-converting enzyme (ACE)-1 in male and female offspring. Of importance, mRNA and protein expression of ACE 2 and angiotensin II receptors was up-regulated only in the male offspring, as a consequence of AMPD. We conclude that sexually dimorphic programming of the pancreatic RAS expression is associated with AMPD diet-mediated development of hyperglycemia.

Effect of peroxisome proliferator activated receptor γ agonist on angiotensin converting enzyme 2 mRNA expression in monocyte-derived macrophages of essential hypertensive patients.

To study the effect of peroxisome proliferator activated receptor γ (PPAR-γ) agonist on the angiotensin converting enzyme 2 (ACE2) mRNA expression in monocyte-derived macrophages of essential hypertensive patients. Totally 57 essential hypertensive patients were randomly divided into three groups: conventional treatment group (n=18), telmisartan group (n=19), and benazepril group (n=20); 20 patients with normal blood pressure were also selected as the control group. Monocyte-derived macrophages were isolated from blood samples of patients in all four groups. The expression of ACE2 mRNA in monocyte-derived macrophages was detected by RT-PCR before treatment and 4 and 12 weeks after treatment. Four and 12 weeks after treatment, the systolic pressure and diastolic pressure of telmisartan group and benazepril group were significantly lower than that of the conventional treatment group (all P<0.01), and the systolic pressure and diastolic pressure of telmisartan group were significantly lower than that of the benazepril group(both P<0.01) .The expression of ACE2 mRNA in monocyte-derived macrophages were significantly lower in essential hypertensive patients than that in control group (P<0.01). After having been treated for 4 weeks and 12 weeks, the expression of ACE2 mRNA in monocyte-derived macrophages of hypertensive patients in telmisartan and benazepril groups were significantly higher than that in conventional treatment group (all P<0.01), and the expression of ACE2 mRNA in telmisartan group was significantly higher than that in benazepril group (both P<0.01). PPAR-γ agonist could increase the ACE2 mRNA expression in monocyte-derived macrophages of essential hypertensive patients.

Podocyte-specific overexpression of human angiotensin-converting enzyme 2 attenuates diabetic nephropathy in mice

Angiotensin-converting enzyme 2 (ACE2) degrades angiotensin II to angiotensin-(1–7) and is expressed in podocytes. Here we overexpressed ACE2 in podocytes in experimental diabetic nephropathy using transgenic methods where a nephrin promoter drove the expression of human ACE2. Glomeruli from these mice had significantly increased mRNA, protein, and activity of ACE2 compared to wild-type mice. Male mice were treated with streptozotocin to induce diabetes. After 16 weeks, there was no significant difference in plasma glucose levels between wild-type and transgenic diabetic mice. Urinary albumin was significantly increased in wild-type diabetic mice at 4 weeks, whereas albuminuria in transgenic diabetic mice did not differ from wild-type nondiabetic mice. However, this effect was transient and by 16 weeks both transgenic and nontransgenic diabetic mice had similar rates of proteinuria. Compared to wild-type diabetic mice, transgenic diabetic mice had an attenuated increase in mesangial area, decreased glomerular area, and a blunted decrease in nephrin expression. Podocyte numbers decreased in wild-type diabetic mice at 16 weeks, but were unaffected in transgenic diabetic mice. At 8 weeks, kidney cortical expression of transforming growth factor-β1 was significantly inhibited in transgenic diabetic mice as compared to wild-type diabetic mice. Thus, the podocyte-specific overexpression of human ACE2 transiently attenuates the development of diabetic nephropathy.

Possible Involvement of Angiotensin-Converting Enzyme 2 and Mas Activation in Inhibitory Effects of Angiotensin II Type 1 Receptor Blockade on Vascular Remodeling

We explored the roles of angiotensin-converting enzyme 2 (ACE2), angiotensin-(1-7), and Mas activation in angiotensin II type 1 receptor blockade-mediated attenuation of vascular remodeling. Vascular injury was induced by polyethylene-cuff placement around the mouse femoral artery. After cuff placement, the mRNA level of both ACE2 and Mas was markedly decreased in wild-type mice, whereas ACE mRNA was not changed. Immunostaining of ACE2 and Mas was observed mainly in the media and was reduced in the injured artery. Administration of angiotensin-(1-7) decreased neointimal formation after cuff placement, whereas administration of [D-Ala(7)] angiotensin-(1-7), a Mas antagonist, increased it. Consistent with these results, we also demonstrated that neointimal formation induced by cuff placement was further increased in ACE2 knockout mice. In angiotensin II type 1a receptor knockout mice, mRNA expression and immunostaining of ACE2 and Mas in the injured artery were greater, with less neointimal formation than in wild-type mice. Increased ACE2 expression in the injured artery was also observed by treatment of wild-type mice with an angiotensin II type 1 receptor blocker, olmesartan. These results suggested that activation of the ACE2-angiotensin-(1-7)-Mas axis is at least partly involved in the beneficial effects of angiotensin II type 1 receptor blockade on vascular remodeling.

High Na intake increases renal angiotensin II levels and reduces expression of the ACE2-AT2R-MasR axis in obese Zucker rats

High sodium intake is known to regulate the renal renin-angiotensin system (RAS) and is a risk factor for the pathogenesis of obesity-related hypertension. The complex nature of the RAS reveals that its various components may have opposing effects on natriuresis and blood pressure regulation. We hypothesized that high sodium intake differentially regulates and shifts a balance between opposing components of the renal RAS, namely, angiotensin-converting enzyme (ACE)-ANG II-type 1 ANG II receptor (AT(1)R) vs. AT(2)-ACE2-angiotensinogen (Ang) (1-7)-Mas receptor (MasR), in obesity. In the present study, we evaluated protein and/or mRNA expression of angiotensinogen, renin, AT(1A/B)R, ACE, AT(2)R, ACE2, and MasR in the kidney cortex following 2 wk of a 8% high-sodium (HS) diet in lean and obese Zucker rats. The expression data showed that the relative expression pattern of ACE and AT(1B)R increased, renin decreased, and ACE2, AT(2)R, and MasR remained unaltered in HS-fed lean rats. On the other hand, HS intake in obese rats caused an increase in the cortical expression of ACE, a decrease in ACE2, AT(2)R, and MasR, and no changes in renin and AT(1)R. The cortical levels of ANG II increased by threefold in obese rats on HS compared with obese rats on normal salt (NS), which was not different than in lean rats. The HS intake elevated mean arterial pressure in obese rats (27 mmHg) more than in lean rats (16 mmHg). This study suggests that HS intake causes a pronounced increase in ANG II levels and a reduction in the expression of the ACE2-AT(2)R-MasR axis in the kidney cortex of obese rats. We conclude that such changes may lead to the potentially unopposed function of AT(1)R, with its various cellular and physiological roles, including the contribution to the pathogenesis of obesity-related hypertension.

Hepatocyte nuclear factors 1α and 1β (HNF1α and HNF1β) are powerful inducers of the enzymatic activity of angiotensin‐converting enzyme 2 (ACE2) in insulin‐secreting cells

Maturity onset diabetes of the young (MODY) types 3 and 5 are caused by deficiency of hepatocyte nuclear factor 1α (HNF1α) and hepatocyte nuclear factor 1β (HNF1β) which bind to similar DNA motifs. Our laboratory has previously shown that: 1) pancreatic angiotensin‐converting enzyme 2 (ACE2) is reduced in diabetes, 2) pancreatic ACE2 gene therapy improves glucose control in diabetic mice, and 3) HNF1β induces expression of ACE2 mRNA in insulinoma cells. However, discordance between ACE2 expression at the mRNA and enzyme activity level is often reported. Furthermore, HNF1α is more prevalent and thought to be more important than HNF1β in differentiated beta cells. Hypothesis: Both HNF1α and HNF1β lead to increased ACE2 mRNA expression as well as elevated ACE2 enzymatic activity in insulin‐secreting cells. Transfection of rat 832/13 insulinoma cells with expression plasmids for HNF1α and HNF1β led to marked (25‐ and 95‐fold, respectively, p &lt; 0.001) induction of ACE2 mRNA and a strong increase (12‐ and 41‐fold, p &lt; 0.001) in ACE2 enzymatic activity. Furthermore, HNF1α and HNF1β induced expression from both of the two known ACE2 promoter regions in mouse βTC‐3 insulinoma cells. The data demonstrate a link between HNF1α/HNF1β, ACE2 activity, and glucose homeostasis. These observations could lead to new therapeutic strategies for the treatment of MODY and type 2 diabetes. Support: NIH/NIDDK (DK084466).

Inhibition of ACE activity contributes to the intestinal structural compensation in a massive intestinal resection rat model

Intestinal adaptation in short bowel syndrome (SBS) consists of increased epithelial cells (ECs) proliferation as well as apoptosis. Angiotensin-converting enzyme (ACE) has been shown to regulate ECs apoptosis. In this study, we investigated the effect of ACE inhibition on intestinal adaptation after small bowel resection (SBR) in a rat model. Sprague-Dawley rats were used and were divided into four groups: (1) Sham group received an ileum transection (n = 6); (2) Sham + ACE-I group received an ileum transaction and lavage with ACE inhibitor (ACE-I, enalaprilat, 2 mg/kg/day) (n = 6); (3) SBS group received a 70 % mid-intestinal resection (n = 6); (4) SBS + ACE-I group received a 70 % mid-intestinal resection and lavage with enalaprilat (2 mg/kg/day) (n = 6). Sampling was done 10 days after surgery. ECs apoptosis was studied by TUNEL staining. ACE, angiotensin II (ANGII) receptor type 1 (AT1R) and receptor type 2 (AT2R) expressions were detected with RT-PCR and immunofluorescent confocal microscopy. SBR leads to significant intestinal hypertrophy. The addition of ACE-I to SBS rat resulted in a significant decline in ECs apoptosis. ACE mRNA expression was significantly elevated after SBS creation (0.24 ± 0.07 vs. 0.42 ± 0.11), and ACE-I administration further increased mucosal ACE mRNA expression (0.54 ± 0.12). Interestingly, AT1R mRNA expression showed a significant decline in the SBS group compared to Sham levels, and ACE-I administration increased AT1R mRNA expression to Sham levels. No significant difference in AT2R mRNA expression was found between Sham and SBS group. These results offer further insight into the role of ACE on intestinal mucosal remolding after massive bowel resection. ACE-I may be beneficial to SBS patients via a reduction of the apoptotic rate, thus facilitating the degree of adaptation.

Inhibition of central angiotensin converting enzyme ameliorates scopolamine induced memory impairment in mice: Role of cholinergic neurotransmission, cerebral blood flow and brain energy metabolism

Evidences indicate that inhibition of central Renin angiotensin system (RAS) ameliorates memory impairment in animals and humans. Earlier we have reported involvement of central angiotensin converting enzyme (ACE) in streptozotocin induced neurodegeneration and memory impairment. The present study investigated the role of central ACE in cholinergic neurotransmission, brain energy metabolism and cerebral blood flow (CBF) in model of memory impairment induced by injection of scopolamine in mice. Perindopril (0.05 and 0.1mg/kg, PO) was given orally for one week before administration of scopolamine (3mg/kg, IP). Then, memory function was evaluated by Morris water maze and passive avoidance tests. CBF was measured by laser Doppler flowmetry. Biochemical and molecular parameters were estimated after the completion of behavioral studies. Scopolamine caused impairment in memory which was associated with reduced CBF, acetylcholine (ACh) level and elevated acetylcholinesterase (AChE) activity and malondialdehyde (MDA) level. Perindopril ameliorated scopolamine induced amnesia in both the behavioral paradigms. Further, perindopril prevented elevation of AChE and MDA level in mice brain. There was a significant increase in CBF and ACh level in perindopril treated mice. However, scopolamine had no significant effect on ATP level and mRNA expression of angiotensin receptors and ACE in cortex and hippocampus. But, perindopril significantly decreased ACE activity in brain without affecting its mRNA expression. The study clearly showed the interaction between ACE and cholinergic neurotransmission and beneficial effect of perindopril can be attributed to improvement in central cholinergic neurotransmission and CBF.

Lingonberry, cranberry and blackcurrant juices affect mRNA expressions of inflammatory and atherothrombotic markers of SHR in a long-term treatment

Flavonoids and other phenolic compounds affect low-grade inflammation related to cardiovascular diseases among other positive health effects. Cardioprotective actions are mainly due to enhanced endothelial function and production of nitric oxide (NO). We investigated vascular anti-inflammatory effects of cranberry (Vaccinium oxycoccos), lingonberry (Vaccinium vitis-idaea) and blackcurrant (Ribes nigrum) juices given as drinking fluid ad libitum to spontaneously hypertensive rats (SHR), a widely used model of human hypertension, in an 8week intervention study. The animals were sacrificed, the aortas cleaned and RNA was extracted. cDNA was prepared for real-time PCR and blood was collected for biochemical analyses. The mRNA expressions of angiotensin-converting enzyme 1 (ACE1), cyclooxygenase 2 (COX2), monocyte chemoattractant protein 1 (MCP1) and P-selectin were significantly reduced in the cranberry and lingonberry groups. These findings suggest that cranberry and lingonberry cold-compressed juices have anti-inflammatory and anti-atherothrombotic actions in long-term treatment of SHR.