Increased AT2R expression is induced by AT1R autoantibody via two axes, Klf-5/IRF-1 and circErbB4/miR-29a-5p, to promote VSMC migration.

Vascular remodeling can be caused by angiotensin II type 1 receptor (AT1R) autoantibody (AT1-AA), although the related mechanism remains unknown. Angiotensin II type 2 receptor (AT2R) plays multiple roles in vascular remodeling through cross-talk with AT1R in the cytoplasm. Here, we aimed to explore the role and mechanism of AT2R in AT1-AA-induced vascular smooth muscle cell (VSMC) migration, which is a key event in vascular remodeling. In vitro and in vivo, we found that AT2R can promote VSMC migration in AT1-AA-induced vascular remodeling. Moreover, AT2R expression was upregulated via Klf-5/IRF-1-mediated transcriptional and circErbB4/miR-29a-5p-mediated posttranscriptional mechanisms in response to AT1-AA. Our data provide a molecular basis for AT1-AA-induced AT2R expression by transcription factors, namely, a circular RNA and a microRNA, and showed that AT2R participated in AT1-AA-induced VSMC migration during the development of vascular remodeling. AT2R may be a potential target for the treatment of AT1-AA-induced vascular diseases.

Differences in the expression of the renin angiotensin system and the kallikrein-kinin system during the course of myocardial infarction in male and female Wistar rats.

BACKGROUND: There is some evidence that components of the renin-angiotensin system and kallikrein-kinin system are not similarly regulated in both sexes. The aim of this work was to analyze the expression of angiotensin-converting enzyme, angiotensin-converting enzyme 2, angiotensin 1 receptor, angiotensin 2 receptor, beta-1 receptor, and beta-2 receptor during the evolution of myocardial infarction. METHODS: Thirty-six male and 36 female Wistar rats were used. Myocardial infarction was induced. Six groups of both sexes were formed, (n=6): (a) sham; (b) 48 h myocardial infarction; (c) one week myocardial infarction; (d) two weeks myocardial infarction; (e) three weeks myocardial infarction and (f) four weeks myocardial infarction. The expression was evaluated by real-time polymerase chain reaction on the penumbra of left ventricle. RESULTS: The mRNA expression of most biomarkers was lower in females than in males. During acute infarction, an increase of all protein expression was found in female and at two weeks while in the male only biomarker changes occurred at three weeks. In addition, in male biomarkers mRNA expression decreased during chronic infarction while in females it did not. CONCLUSIONS: The renin-angiotensin system and kallikrein-kinin system biomarkers expression occurs at earlier times in the female than in the male rat. In addition, during chronic myocardial infarction these biomarkers remained unchanged in females while in males they decreased.

Hiding in Plain Sight: an Approach to Treating Patients with Severe COVID-19 Infection.

Patients with COVID-19 infection are at risk of acute respiratory disease syndrome (ARDS) and death. The tissue receptor for COVID-19 is ACE2, and higher levels of ACE2 can protect against ARDS. Angiotensin receptor blockers and statins upregulate ACE2. Clinical trials are needed to determine whether this drug combination might be used to treat patients with severe COVID-19 infection.

Ethanol Withdrawal Alters the Oxidative State of the Heart Through AT1-Dependent Mechanisms.

AIMS: We investigated the cardiac effects of ethanol withdrawal and the possible role of AT1 receptors in such response. METHODS: Male Wistar rats were treated with increasing doses of ethanol (3 to 9%, vol./vol.) for 21 days. The cardiac effects of ethanol withdrawal were investigated 48 h after abrupt discontinuation of ethanol. Some animals were orally treated with losartan (10 mg/kg/day), a selective AT1 receptor antagonist. RESULTS: Ethanol withdrawal did not affect serum levels of creatine kinase (CK)-MB. Losartan prevented ethanol withdrawal-induced increase in superoxide anion (O2•-) production in the left ventricle (LV). However, ethanol withdrawal did no alter the levels of thiobarbituric acid reactive substances (TBARS) or the expression of Nox1, Nox2 or Nox4 were found in the LV. Ethanol withdrawal reduced the concentration of hydrogen peroxide (H2O2) in the LV and this response was prevented by losartan. Ethanol withdrawal increased catalase activity in the LV and losartan attenuated this response. No changes on superoxide dismutase (SOD) activity or expression were detected in the LV during ethanol withdrawal. The expression of AT1, AT2 or angiotensin converting enzyme (ACE) was not affected by ethanol withdrawal. Similarly, no changes on the expression of ERK1/2, SAPK/JNK, COX-1 or COX-2 were found in the LV during ethanol withdrawal. CONCLUSIONS: Ethanol withdrawal altered the cardiac oxidative state through AT1-dependent mechanisms. Our findings showed a role for angiotensin II/AT1 receptors in the initial steps of the cardiac effects induced by ethanol withdrawal.

Expression of the intrarenal angiotensin receptor and the role of renin-angiotensin system inhibitors in IgA nephropathy.

The critical role of the intrarenal renin-angiotensin system (RAS) in the development of kidney disease has been well demonstrated in animal and cell-culture experiments, but evidence from human kidney tissues is lacking. In this study, we screened 438 patients with IgA nephropathy (IgAN) and analyzed their clinical characteristics. Renal biopsy revealed the expression of angiotensin II type 1 receptor (AT1R), angiotensin II type 2 receptor (AT2R), and MAS receptor (MASR) in the tissues of 260 patients not treated with RAS inhibitors, 32 patients treated with angiotensin-converting enzyme inhibitors (ACEIs), and 89 patients treated with angiotensin receptor blockers (ARBs). The correlations in expression among these three receptors and the results of Oxford typing were analyzed, together with the ability of ACEIs and ARBs to reduce proteinuria and the effects of ARBs on AT1R and AT2R expression. The results showed significantly higher AT1R, AT2R, and MASR expression in the M1 group (mesangial score > 0.5) than in the M0 group (mesangial score < 0.5), significantly higher AT1R expression in the S1 group (presence of segmental glomerulosclerosis) than in the S0 group (absence of segmental glomerulosclerosis); AT1R expression in the C2 group (crescent formation > 25%) was significantly higher than in the C0 (crescent formation = 0) and C1 (crescent formation < 25%) groups. Patients treated with an ARB for < 6 months had significantly lower urinary protein levels than those taking these drugs for > 6 months. These findings imply that overexpression of AT1R on the mesangial cells of IgAN patients is associated with mesangial cell proliferation, glomerular segmental sclerosis, and crescent formation. In addition, long-term administration of ARB may decrease the efficacy of these medications in terms of reducing proteinuria.

Pregnancy upregulates angiotensin type 2 receptor expression and increases blood flow in uterine arteries of rats.

Normal pregnancy is associated with decreased uterine vascular contraction and increased blood flow even though angiotensin II (AngII) levels are increased. AngII not only activates the angiotensin type 1 receptor (AT1R) to mediate vasoconstriction but also angiotensin type 2 receptor (AT2R) to cause vasodilation. We hypothesized that upregulation of AT2R expression and function accounts for increased uterine artery blood flow during pregnancy. Virgin, pregnant (at different days of gestation) and post-partum Sprague-Dawley rats were used to determine uterine artery hemodynamics using micro ultrasound and plasma angiotensin II levels by ELISA. Isolated uterine arteries were examined for AT1R and AT2R expression and isometric contraction/relaxation. Plasma AngII levels were steady up to mid-pregnancy, increased as pregnancy advanced, reaching a peak in late pregnancy, and then restored to pre-pregnant levels after delivery. The pattern of increase in AngII levels mirrored a parallel increase in uterine blood flow. AT1R expression did not change, but AT2R expression increased during pregnancy correlating with uterine blood flow increase. Treatment with the AT2R antagonist PD123319 reduced uterine arterial blood flow. Vasoconstriction to angiotensin II was blunted in pregnant rats. Treatment with PD123319 caused greater enhancement of AngII contraction in pregnant than virgin rats. Ex vivo exposure of estradiol to uterine arterial rings dose dependently upregulated AT2R expression, that was inhibited by estrogen receptor antagonist. These results demonstrate that elevated AngII levels during gestation induce an increase in uterine blood flow via heightened AT2R-mediated signaling. Estrogens appear to directly upregulate uterine vascular AT2R independent of any endogenous factors.

Diminazene aceturate prevents nephropathy by increasing glomerular ACE2 and AT2 receptor expression in a rat model of type1 diabetes.

BACKGROUND AND PURPOSE: One of the protective actions of angiotensin converting enzyme-2 (ACE2) is the inactivation of angiotensin II. Expression and activity of ACE2 was reduced in glomeruli of diabetic patients and in animal models of diabetes. Recently the potential role of recombinant ACE2 administration in preventing diabetic nephropathy (DN) has been shown. Here we have tested the effects of the ACE2 activator, diminazene aceturate (DIZE), in a model of DN. EXPERIMENTAL APPROACH: Male Wistar rats were rendered diabetic using a single dose of streptozotocin (55 mg·kg-1 , i.p.). After 4 weeks, diabetic animals were divided into experimental groups and treated with DIZE, at a low dose (5 mg·kg-1 ·day-1 ), a high dose (15 mg·kg-1 ·day-1 ) and the high dose with of the AT2 receptor antagonist PD123319 (10 mg·kg-1 ·day-1 ). At the end of the treatment , kidneys from all the groups were collected and processed separately for glomerular isolation, protein isolation, mRNA extraction and for immunohistochemical studies. KEY RESULTS: Treatment with DIZE restored ACE2 expression in glomeruli and increased expression of AT2 receptors in whole kidney and isolated glomeruli of diabetic animals. DIZE administration reduced angiotensin II levels and increased angiotensin-(1-7) levels in diabetic kidney. However, PD123319 treatment reversed all these actions of DIZE. CONCLUSIONS AND IMPLICATIONS: DIZE treatment reduced diabetes-induced renal damage as shown by reduction of fibrosis and apoptosis. These protective actions of DIZE were blocked by the AT2 receptor antagonist. Taken together, these results suggest that DIZE protected against DN through the ACE2/angiotensin-(1-7)/ AT2 receptor axis.

The influence of TNF-α and Ang II on the proliferation, migration and invasion of HepG2 cells by regulating the expression of GRK2.

PURPOSE: Hepatocellular carcinoma (HCC) is a common digestive system malignancy that is associated with a poor prognosis. This study researched the interaction of tumor necrosis factor-α (TNF-α) and angiotensin II (Ang II) in HCC cells proliferation, migration and invasion and examined their influence on the expression of G protein-coupled receptor kinase 2 (GRK2) and relevant receptors. METHODS: Cell Counting Kit-8 and Transwell assays were performed to evaluate the effects of TNF-α and Ang II on HepG2 cells proliferation, migration and invasion. Flow cytometry was used to investigate the expression of tumor necrosis factor receptor 1 (TNFR1), angiotensin II type 1 (AT1R) and type 2 receptors (AT2R) on the surface of HepG2 cells. Additionally, Western blot was performed to assess the modulation of GRK2 expression by TNF-α and Ang II in HepG2 cells. Meanwhile, GRK2 siRNA-transfected HepG2 cells were used to confirm the effects of GRK2, TNF-α and Ang II on the proliferation, migration and invasion of GRK2-knockdown HCC cells. Finally, the expression of TNF-α, Ang II, TNFR1, AT1R, AT2R and GRK2 proteins in HCC, tumor-adjacent and normal liver tissues were tested by immunohistochemistry. RESULTS: The data demonstrated that TNF-α and Ang II can enhance the proliferation, migration and invasion of HepG2 cells through suppressing GRK2 expression but that the two reagents combined did not have synergistic effects. Moreover,overexpression of TNFR1 and AT1R perhaps promoted the formation and progression of HCC, while high AT2R expression had the opposite effect. CONCLUSIONS: This study provides new ideas for the prevention and treatment of HCC by researching the interaction and probable mechanism of different bioactive factors associated with HCC.

Early treatment with losartan effectively ameliorates hypertension and improves vascular remodeling and function in a prehypertensive rat model.

AIMS: Pharmacological treatment of prehypertension may ameliorate hypertension and improve vascular structure and function. This study investigated 1) whether early treatment with either losartan or amlodipine at the onset of prehypertension can prevent hypertension and 2) whether losartan and amlodipine equally improve vascular remodeling and function in a rat model of hypertension. MATERIALS AND METHODS: Stroke-prone spontaneously hypertensive (SHRSP) rats were administered losartan, amlodipine or saline for 6 or 16weeks at the onset of prehypertension. Wistar-Kyoto rats were used as a control. All groups were observed for 40weeks. Systolic blood pressure was measured using the tail-cuff method. Vascular structure and function were determined by microscopy and vascular ring contractility assays, respectively. Angiotensin II (Ang II) and aldosterone (Aldo) were measured by radioimmunoassays. Angiotensin II type 1 receptor (AT1R) and angiotensin II type 2 receptor (AT2R) expression was measured by western blot. KEY FINDINGS: Losartan effectively reduced progression from prehypertension to hypertension as well as vascular remodeling and improved vascular contractility in SHRSP rats. Long-term losartan (16weeks) had greater benefits than short-term (6weeks) treatment. Losartan increased Ang II and decreased Aldo levels in the serum and vessel walls of resistance vessels in a time-dependent manner. Losartan significantly decreased AT1R and increased AT2R vascular expression. Amlodipine had no effect on vascular AT1R and AT2R expression. SIGNIFICANCE: Losartan administered at the onset of prehypertension is more effective than amlodipine in ameliorating hypertension and improving vascular remodeling and function, which is likely mediated by the renin-angiotensin-aldosterone system.

An Intronic Enhancer Element Regulates Angiotensin II Type 2 Receptor Expression during Satellite Cell Differentiation, and Its Activity Is Suppressed in Congestive Heart Failure.

Patients with advanced congestive heart failure (CHF) or chronic kidney disease often have increased angiotensin II (Ang II) levels and cachexia. We previously demonstrated that Ang II, via its type 1 receptor, causes muscle protein breakdown and apoptosis and inhibits satellite cell (SC) proliferation and muscle regeneration, likely contributing to cachexia in CHF and chronic kidney disease. In contrast, Ang II, via its type 2 receptor (AT2R) expression, is robustly induced during SC differentiation, and it potentiates muscle regeneration. To understand the mechanisms regulating AT2R expression and its potential role in muscle regeneration in chronic diseases, we used a mouse model of CHF and found that muscle regeneration was markedly reduced and that this was accompanied by blunted increase of AT2R expression. We performed AT2R promoter reporter analysis during satellite cell differentiation and found that the 70 bp upstream of the AT2R transcription start site contain a core promoter region, and regions upstream of 70 bp to 3 kbp are dispensable for AT2R induction. Instead, AT2R intron 2 acts as a transcriptional enhancer during SC differentiation. Further deletion/mutation analysis revealed that multiple transcription factor binding sites in the +286/+690 region within intron 2 coordinately regulate AT2R transcription. Importantly, +286/+690 enhancer activity was suppressed in CHF mouse skeletal muscle, suggesting that AT2R expression is suppressed in CHF via inhibition of AT2R intronic enhancer activity, leading to lowered muscle regeneration. Thus targeting intron 2 enhancer element could lead to the development of a novel intervention to increase AT2R expression in SCs and potentiate skeletal muscle regenerative capacity in chronic diseases.

Nicotine Mediates CD161a+ Renal Macrophage Infiltration and Premature Hypertension in the Spontaneously Hypertensive Rat.

RATIONALE: Renal inflammation contributes to the pathophysiology of hypertension. CD161a+ immune cells are dominant in the (SHR) spontaneously hypertensive rat and expand in response to nicotinic cholinergic activation. OBJECTIVE: We aimed to phenotype CD161a+ immune cells in prehypertensive SHR after cholinergic activation with nicotine and determine if these cells are involved in renal inflammation and the development of hypertension. METHODS AND RESULTS: Studies used young SHR and WKY (Wistar-Kyoto) rats. Splenocytes and bone marrow cells were exposed to nicotine ex vivo, and nicotine was infused in vivo. Blood pressures, kidney, serum, and urine were obtained. Flow cytometry, Luminex/ELISA, immunohistochemistry, confocal microscopy, and Western blot were used. Nicotinic cholinergic activation induced proliferation of CD161a+/CD68+ macrophages in SHR-derived splenocytes, their renal infiltration, and premature hypertension in SHR. These changes were associated with increased renal expression of MCP-1 (monocyte chemoattractant protein-1) and VLA-4 (very-late antigen-4). LLT1 (lectin-like transcript 1), the ligand for CD161a, was overexpressed in SHR kidney, whereas vascular cellular and intracellular adhesion molecules were similar to those in WKY. Inflammatory cytokines were elevated in SHR kidney and urine after nicotine infusion. Nicotine-mediated renal macrophage infiltration/inflammation was enhanced in denervated kidneys, not explained by angiotensin II levels or expression of angiotensin type-1/2 receptors. Moreover, expression of the anti-inflammatory α7-nAChR (α7-nicotinic acetylcholine receptor) was similar in young SHR and WKY rats. CONCLUSIONS: A novel, inherited nicotinic cholinergic inflammatory effect exists in young SHR, measured by expansion of CD161a+/CD68+ macrophages. This leads to renal inflammation and premature hypertension, which may be partially explained by increased renal expression of LLT-1, MCP-1, and VLA-4.

Increased hydrogen peroxide impairs angiotensin II contractions of afferent arterioles in mice after renal ischaemia-reperfusion injury.

AIM: Renal ischaemia-reperfusion injury (IRI) increases angiotensin II (Ang II) and reactive oxygen species (ROS) that are potent modulators of vascular function. However, the roles of individual ROS and their interaction with Ang II are not clear. Here we tested the hypothesis that IRI modulates renal afferent arteriolar responses to Ang II via increasing superoxide (O2-) or hydrogen peroxide (H2 O2 ). METHODS: Renal afferent arterioles were isolated and perfused from C57BL/6 mice 24 h after IRI or sham surgery. Responses to Ang II or noradrenaline were assessed by measuring arteriolar diameter. Production of H2 O2 and O2- was assessed in afferent arterioles and renal cortex. Activity of SOD and catalase, and mRNA expressions of Ang II receptors were assessed in pre-glomerular arterioles and renal cortex. RESULTS: Afferent arterioles from mice after IRI had a reduced maximal contraction to Ang II (-27±2 vs. -42±1%, P < 0.001), but retained a normal contraction to noradrenaline. Arterioles after IRI had a 38% increase in H2 O2 (P < 0.001) and a 45% decrease in catalase activity (P < 0.01). Contractions were reduced in normal arterioles after incubation with H2 O2 (-22±2 vs. -42±1%, P < 0.05) similar to the effects of IRI. However, the impaired contractions were normalized by incubation with PEG catalase despite a reduced AT1 R expression. CONCLUSIONS: Renal IRI in mice selectively impairs afferent arteriolar responses to Ang II because of H2 O2 accumulation that is caused by a reduced catalase activity. This could serve to buffer the effect of Ang II after IRI and may be a protective mechanism.

Early postnatal treatment with soluble epoxide hydrolase inhibitor or 15-deoxy-Δ(12,14)-prostagandin J2 prevents prenatal dexamethasone and postnatal high saturated fat diet induced programmed hypertension in adult rat offspring.

Prenatal dexamethasone (DEX) exposure, postnatal high-fat (HF) intake, and arachidonic acid pathway are closely related to hypertension. We tested whether a soluble epoxide hydrolase (SEH) inhibitor, 12-(3-adamantan-1-yl-ureido)-dodecanoic acid (AUDA) or 15-deoxy-Δ(12,14)-prostagandin J2 (15dPGJ2) therapy can rescue programmed hypertension in the DEX+HF two-hit model. Four groups of Sprague Dawley rats were studied: control, DEX+HF, AUDA, and 15dPGJ2. Dexamethasone (0.1mg/kg body weight) was intraperitoneally administered to pregnant rats from gestational day 16-22. Male offspring received high-fat diet (D12331, Research Diets) from weaning to 4 months of age. In AUDA group, mother rats received 25mg/L in drinking water during lactation. In the 15dPGJ2 group, male offspring received 15dPGJ2 1.5mg/kg BW by subcutaneous injection once daily for 1 week after birth. We found postnatal HF diet aggravated prenatal DEX-induced programmed hypertension, which was similarly prevented by early treatment with AUDA or 15dPGJ2. The beneficial effects of AUDA and 15d-PGJ2 therapy include inhibition of SEH, increases of renal angiotensin converting enzyme-2 (ACE2) and angiotensin II type 2 receptor (AT2R) protein levels, and restoration of nitric oxide bioavailability. Better understanding of the impact of arachidonic acid pathway in the two-hit model will help prevent programmed hypertension in children exposed to corticosteroids and postnatal HF intake.

Angiolymphoid hyperplasia with eosinophilia developing within a port wine stain.

A 19-year-old male with a port wine stain on the base of his neck presented with a 5-month history of gradual thickening of the involved skin which interfered with clothing and caused repeated bleeding. The lesion was excised and histopathologic examination revealed angiolymphoid hyperplasia with eosinophilia (ALHE) arising from the pre-existing port wine stain - a rare finding with only one previously reported case. Additionally the lesion was associated with elevated serum renin levels which virtually normalized following excision of the lesion. We further demonstrated the expression of angiotensin converting enzyme and angiotensin II receptors 1 and 2 by the lesion and discuss the possible role of the renin-angiotensin system in this condition.

Prehypertensive treatment with losartan, however not amlodipine, leads to long-term effects on blood pressure and reduces the risk of stroke in spontaneously hypertensive stroke-prone rats.

The current study investigated the efficacy of losartan and amlodipine in protecting spontaneously hypertensive stroke-prone (SHRSP) rats against the risk of stroke. SHRSP rats were administered losartan, amlodipine or the vehicle for 6 weeks. There were no significant differences in systolic blood pressure (SBP) in rats treated with losartan or amlodipine, however, following drug withdrawal, rats treated with losartan maintained reduced SBP for a longer time compared with rats treated with amlodipine. In addition, rats treated with losartan exhibited thinner vascular walls and improved systolic and diastolic function. Clinical stroke scores in the losartan group were significantly reduced compared with those in the amlodipine and vehicle groups. However, rats treated with losartan exhibited higher levels of angiotensin II and lower levels of aldosterone in the serum and brain cortex compared with the vehicle and amlodipine-treated rats. Furthermore, losartan significantly reduced the abnormal expression of angiotensin II receptors type 1 and 2 in SHRSP rats, whilst amlodipine did not. These results suggest that losartan may be more efficacious than amlodipine in ameliorating blood pressure deterioration and reducing stroke risk in SHRSP rats via regulation of the renin angiotensin system.

Attenuation of myocardial fibrosis with curcumin is mediated by modulating expression of angiotensin II AT1/AT2 receptors and ACE2 in rats.

Curcumin is known to improve cardiac function by balancing degradation and synthesis of collagens after myocardial infarction. This study tested the hypothesis that inhibition of myocardial fibrosis by curcumin is associated with modulating expression of angiotensin II (Ang II) receptors and angiotensin-converting enzyme 2 (ACE2). Male Sprague Dawley rats were subjected to Ang II infusion (500 ng/kg/min) using osmotic minipumps for 2 and 4 weeks, respectively, and curcumin (150 mg/kg/day) was fed by gastric gavage during Ang II infusion. Compared to the animals with Ang II infusion, curcumin significantly decreased the mean arterial blood pressure during the course of the observation. The protein level of the Ang II type 1 (AT1) receptor was reduced, and the Ang II type 2 (AT2) receptor was up-regulated, evidenced by an increased ratio of the AT2 receptor over the AT1 receptor in the curcumin group (1.2±0.02%) vs in the Ang II group (0.7±0.03%, P<0.05). These changes were coincident with less locally expressed AT1 receptor and enhanced AT2 receptor in the intracardiac vessels and intermyocardium. Along with these modulations, curcumin significantly decreased the populations of macrophages and alpha smooth muscle actin-expressing myofibroblasts, which were accompanied by reduced expression of transforming growth factor beta 1 and phosphorylated-Smad2/3. Collagen I synthesis was inhibited, and tissue fibrosis was attenuated, as demonstrated by less extensive collagen-rich fibrosis. Furthermore, curcumin increased protein level of ACE2 and enhanced its expression in the intermyocardium relative to the Ang II group. These results suggest that curcumin could be considered as an add-on therapeutic agent in the treatment of fibrosis-derived heart failure patient who is intolerant of ACE inhibitor therapy.

Valsartan-induced cardioprotection involves angiotensin II type 2 receptor upregulation in isolated ischaemia and reperfused rat hearts.

The angiotensin II type 1 receptor (AT1R) antagonist protects the heart against acute ischaemia-reperfusion injury. The underlying mechanism is unclear. To determine the effects of angiotensin II type 1 receptor blockade, valsartan on AT1 and AT2 receptor during ischaemia reperfusion in isolated rat, the hearts of 24 SD rats were isolated, linked to Langendorff perfusion apparatus, and exposed to ischaemia for 30 min.The left ventricular systolic pressure, maximal uprising velocity of left ventricular pressure (+dp/dt(max)), maximal decreasing velocity of left ventricular pressure (-dp/dt(max)) and coronary flow were measured after stabilization of the perfusion.The isoenzyme of creatine kinase in the effluent liquid from the heart, AT1 and AT2 receptor mRNA and protein expression were measured after stabilization of the perfusion. The results showed that ischaemia-reperfusion induced a marked decrease in left ventricular systolic pressure, +dp/dt(max) and -dp/dt(max) indicating severe cardiac dysfunction and decreased coronary effluence. Concurrently, myocardial AT1 and AT2 receptor mRNA and protein expression were increased with valsartan. However, AT2 receptor mRNA and protein expression decreased during ischaemia-reperfusion. The creatine kinase levels at different time points of the valsartan group were significantly lower. The results suggested that valsartan improved left ventricular function and increased coronary effluence because the angiotensin receptor blocker valsartan induced cardioprotection associated with upregulating AT2 receptor protein and mRNA expression after ischaemia-reperfusion in isolated rats.

Maternal High-Fat Diet Causes a Sex-Dependent Increase in AGTR2 Expression and Cardiac Dysfunction in Adult Male Rat Offspring.

Maternal high-fat diet (HFD) is associated with cardiovascular disease later in life. This study tested the hypothesis that maternal HFD causes programming of increased cardiac angiotensin II receptor type 2 (AGTR2) expression, resulting in heightened cardiac susceptibility to ischemic injury in male offspring in a sex-dependent manner. Pregnant rats were divided between control and HFD (HFD-fed during gestation) groups. Maternal HFD resulted in cardiac hypertrophy in only male offspring, but had no effect on cardiac systolic and diastolic function in both male and female offspring. In addition, maternal HFD increased heart susceptibility to ischemia-reperfusion injury in adult male offspring, but not female offspring. There was an increase in Agtr2 mRNA and protein abundance in male, but not female offspring. However, maternal HFD had no effect on angiotensin II receptor type 1 (AGTR1) expression in both male and female offspring. HFD resulted in decreased glucocorticoid receptors (GRs) binding to the glucocorticoid response elements at the Agtr2 promoter, which was due to decreased GRs in the hearts of adult male offspring. Inhibition of AGTR2 with PD123319 abrogated maternal HFD-induced increase in cardiac ischemic vulnerability in male adult rats. The results demonstrate that maternal HFD causes programming of increased Agtr2 gene expression in the heart by downregulation of GR, contributing to the heightened cardiac vulnerability to ischemic injury in adult male offspring in a sex-dependent manner.

Angiotensin-(1-7) Suppresses Hepatocellular Carcinoma Growth and Angiogenesis via Complex Interactions of Angiotensin II Type 1 Receptor, Angiotensin II Type 2 Receptor and Mas Receptor.

We recently confirmed that angiotensin II (Ang II) type 1 receptor (AT1R) was overexpressed in hepatocellular carcinoma tissue using a murine hepatoma model. Angiotensin(Ang)-(1-7) has been found beneficial in ameliorating lung cancer and prostate cancer. Which receptor of Ang-(1-7) is activated to mediate its effects is much speculated. This study was designed to investigate the effects of Ang-(1-7) on hepatocellular carcinoma, as well as the probable mechanisms. H22 hepatoma-bearing mice were randomly divided into five groups for treatment: mock group, low-dose Ang-(1-7), high-dose Ang-(1-7), high-dose Ang-(1-7) + A779 and high-dose Ang-(1-7) + PD123319. Ang-(1-7) treatment inhibited tumor growth time- and dose-dependently by arresting tumor proliferation and promoting tumor apoptosis as well as inhibiting tumor angiogenesis. The effects of Ang-(1-7) on tumor proliferation and apoptosis were reversed by coadministration with A779 or PD123319, whereas the effects on tumor angiogenesis were completely reversed by A779 but not by PD123319. Moreover, Ang-(1-7) downregulated AT1R mRNA, upregulated mRNA levels of Ang II type 2 receptor (AT2R) and Mas receptor (MasR) and p38-MAPK phosphorylation and suppressed H22 cell-endothelial cell communication. Thus, Ang-(1-7) administration suppresses hepatocellular carcinoma via complex interactions of AT1R, AT2R and MasR and may provide a novel and promising approach for the treatment of hepatocellular carcinoma.

Low functional programming of renal AT2R mediates the developmental origin of glomerulosclerosis in adult offspring induced by prenatal caffeine exposure.

Our previous study has indicated that prenatal caffeine exposure (PCE) could induce intrauterine growth retardation (IUGR) of offspring. Recent research suggested that IUGR is a risk factor for glomerulosclerosis. However, whether PCE could induce glomerulosclerosis and its underlying mechanisms remain unknown. This study aimed to demonstrate the induction to glomerulosclerosis in adult offspring by PCE and its intrauterine programming mechanisms. A rat model of IUGR was established by PCE, male fetuses and adult offspring at the age of postnatal week 24 were euthanized. The results revealed that the adult offspring kidneys in the PCE group exhibited glomerulosclerosis as well as interstitial fibrosis, accompanied by elevated levels of serum creatinine and urine protein. Renal angiotensin II receptor type 2 (AT2R) gene expression in adult offspring was reduced by PCE, whereas the renal angiotensin II receptor type 1a (AT1aR)/AT2R expression ratio was increased. The fetal kidneys in the PCE group displayed an enlarged Bowman's space and a shrunken glomerular tuft, accompanied by a reduced cortex width and an increase in the nephrogenic zone/cortical zone ratio. Observation by electronic microscope revealed structural damage of podocytes; the reduced expression level of podocyte marker genes, nephrin and podocin, was also detected by q-PCR. Moreover, AT2R gene and protein expressions in fetal kidneys were inhibited by PCE, associated with the repression of the gene expression of glial-cell-line-derived neurotrophic factor (GDNF)/tyrosine kinase receptor (c-Ret) signaling pathway. These results demonstrated that PCE could induce dysplasia of fetal kidneys as well as glomerulosclerosis of adult offspring, and the low functional programming of renal AT2R might mediate the developmental origin of adult glomerulosclerosis.