AT1 mRNA Research Articles

Expression of Angiotensin II Types 1 and 2 Receptors in Endometriotic Lesions

Background/Aim: The aim of this study was to evaluate the gene and protein expression of angiotensin type (AT) 1, AT2 receptors in endometriotic lesions and its relation to prostaglandin (PG) synthases. Materials and Methods: Endometriosis samples were obtained from 32 patients with endometriotic cysts. Endometrial tissues were obtained during operations for benign gynecological conditions. The expression of the AT1 and AT2 receptor mRNA and that of PG-endoperoxide synthase 2 and microsomal PGE2 synthase-1 (mPGES-1) was examined by quantitative RT-PCR. Immunohistochemical staining was performed for these receptors. Results: AT1 and AT2 receptor proteins were mostly located in endometrial glandular epithelium and some stromal cells. Immunoreactivity of the receptor proteins was observed in both the eutopic endometrium and endometriotic lesions. The AT1/AT2 ratio in endometriotic cysts (median 7.29, range 1.88-187.60) was significantly increased compared with that in the eutopic endometrium in the proliferative-phase in controls (median 1.01, range 0.37-2.09, p < 0.001). There was a relationship between the AT1 mRNA expression and that of mPGES-1 mRNA in the endometriotic cysts (r = 0.394089, p < 0.05). There was a significant relationship between the mRNA expression of the AT2 receptor and that of mPGES-1 in eutopic endometrium of non-endometriotic control (r = 0.610714, p < 0.05). Conclusion: Renin-angiotensin system may play an important role in the pathophysiology of endometriosis.

Expression of apical Na(+)-L-glutamine co-transport activity, B(0)-system neutral amino acid co-transporter (B(0)AT1) and angiotensin-converting enzyme 2 along the jejunal crypt-villus axis in young pigs fed a liquid formula.

Gut apical amino acid (AA) transport activity is high at birth and during suckling, thus being essential to maintain luminal nutrient-dependent mucosal growth through providing AA as essential metabolic fuel, substrates and nutrient stimuli for cellular growth. Because system-B(0) Na(+)-neutral AA co-transporter (B(0)AT1, encoded by the SLC6A19 gene) plays a dominant role for apical uptake of large neutral AA including L-Gln, we hypothesized that high apical Na(+)-Gln co-transport activity, and B(0)AT1 (SLC6A19) in co-expression with angiotensin-converting enzyme 2 (ACE2) were expressed along the entire small intestinal crypt-villus axis in young animals via unique control mechanisms. Kinetics of Na(+)-Gln co-transport activity in the apical membrane vesicles, prepared from epithelial cells sequentially isolated along the jejunal crypt-villus axis from liquid formula-fed young pigs, were measured with the membrane potential being clamped to zero using thiocyanate. Apical maximal Na(+)-Gln co-transport activity was much higher (p<0.05) in the upper villus cells than in the middle villus (by 29%) and the crypt (by 30%) cells, whereas Na(+)-Gln co-transport affinity was lower (p<0.05) in the upper villus cells than in the middle villus and the crypt cells. The B(0)AT1 (SLC6A19) mRNA abundance was lower (p<0.05) in the crypt (by 40-47%) than in the villus cells. There were no significant differences in B(0)AT1 and ACE2 protein abundances on the apical membrane among the upper villus, the middle villus and the crypt cells. Our study suggests that piglet fast growth is associated with very high intestinal apical Na(+)-neutral AA uptake activities via abundantly co-expressing B(0)AT1 and ACE2 proteins in the apical membrane and by transcribing the B(0)AT1 (SLC6A19) gene in the epithelia along the entire crypt-villus axis.

Intestinal B(0)AT1 (SLC6A19) and PEPT1 (SLC15A1) mRNA levels in European sea bass (Dicentrarchus labrax) reared in fresh water and fed fish and plant protein sources.

The objective of the present study was to examine the effect of diets with descending fish meal (FM) inclusion levels and the addition of salt to the diet containing the lowest FM level on growth performances, feed conversion ratio, and intestinal solute carrier family 6 member 19 (SLC6A19) and oligopeptide transporter 1 (PEPT1) transcript levels, in freshwater-adapted European sea bass (Dicentrarchus labrax). We first isolated by molecular cloning and sequenced a full-length cDNA representing the neutral amino acid transporter SLC6A19 in sea bass. The cDNA sequence was deposited in GenBank database (accession no. KC812315). The twelve transmembrane domains and the 'de novo' prediction of the three-dimensional structure of SLC6A19 protein (634 amino acids) are presented. We then analysed diet-induced changes in the mRNA copies of SLC6A19 and PEPT1 genes in different portions of sea bass intestine using real-time RT-PCR. Sea bass were fed for 6 weeks on different diets, with ascending levels of fat or descending levels of FM, which was replaced with vegetable meal. The salt-enriched diet was prepared by adding 3 % NaCl to the diet containing 10 % FM. SLC6A19 mRNA in the anterior and posterior intestine of sea bass were not modulated by dietary protein sources and salt supplementation. Conversely, including salt in a diet containing a low FM percentage up-regulated the mRNA copies of PEPT1 in the hindgut. Fish growth correlated positively with the content of FM in the diets. Interestingly, the addition of salt to the diet containing 10 % FM improved feed intake, as well as specific growth rate and feed conversion ratio.

Abstract 643: Unique Cortico-medullary Topology Of D1R, AT1R And NADPH-oxidase Contributes To Hypertension And Salt-sensitivity In Aging Rats

Aging Fisher Brown Norway (FBN) rats exhibit hypertensive phenotype due in part to increased oxidative stress and impaired dopamine D1 receptor (D1R) and angiotensin AT1 receptor (AT1R) functions in the aging kidneys. Here, we tested if these rats develop salt-sensitivity and examined its mechanisms. Adult (2- month) and aged (20- month) FBNs were treated with normal (NS, 0.4%) and high ( HS, 8%) salt for 4-weeks, conscious blood pressure (BP) measured and kidneys harvested for analyses. BP was higher in aged (120 mmHg) than in adult (113 mmHg) rats fed NS, which further increased (126 mmHg) with HS in aged rats. D1R mRNA and protein increased in cortex [NS vs HS: mRNA, 1.00 ± 0.0 vs 1. 21 ± 0.06 AU; Protein, 56.1 ± 2.01 vs 68.8 ± 3.08 DU] and medulla [NS vs HS: mRNA, 1.0 ± 0.0 vs 1.11 ± 0.12 AU; Protein, 54.2 ± 2.89 vs 70.3 ± 1.76 AU] with HS in adult rats. AT1R mRNA in cortex and medulla was higher in aged than in adult rats irrespective of salt treatment [Adult vs Old: Cortex, 1.0 ± 0.00 vs 5.04 ± 0.42; Medulla, 1.0 ± 0.00 vs 5.07 ± 0.09 AU]. However, its protein increased in medulla with HS in only aged rats [NS vs HS: 55.68 ± 4.8 vs 80.68 ± 8.3 DU]. 91phoxgp-NADPH-oxidase mRNA followed a similar pattern as of AT1 mRNA in both cortex and medulla of aged rats. However, its protein was higher in cortex of aged rats irrespective of salt intake [Adult vs Old: NS: 60.3 ± 7.2 vs 112.1 ± 8.6; HS: 61.9 ± 3.7 vs 94.25 ± 15.7 DU], but increased only with HS in medulla [Adult vs Old: 58.3 ± 6.3 vs 86.7 ± 7.2 DU] in these rats. Furthermore, NHE3 protein levels in the medulla were higher irrespective of salt treatment in aged rats [Adult vs Old: NS: 44.0 ± 5.8 vs 62.3 ± 4.6; HS: 45.4 ± 4.7 vs 65.4 ± 2.8 DU]. However, salt treatment increased the levels of Na,K-ATPase protein in the medulla of aged rats (NS vs HS: 11.8 ± 2.2 vs 18.9 ± 2.3 DU). Interestingly, renin levels in cortex were higher than in medulla irrespective of salt intake in aged rats (Cortex vs Medulla: NS: 84. 2 ± 4.5 vs 46. 32 ± 8.18; HS: 82.2 ± 1.18 vs 52.7 ± 3.51 ng/ml/hr). These data suggest that cortical renin and gp91phox-NADPH-oxidase together with medullary NHE-3 contribute to age-related hypertension, while D1R (cortical and medullary) together with medullary AT1R, gp91phox-NADPH-oxidase and Na, K-ATPase contribute to salt-sensitivity in aging FBNs.

Protective effect of an angiotensin-converting-enzyme inhibitor on neurogenic pulmonary edema in rabbits

Neurogenic pulmonary edema (NPE ) was indicative of poor prognosis in the epidemic of enterovirus 71 infections. The pathogenesis of NPE remains poorly understood. The objectives of this experimental study were to explore whether RAS is activated during NPE in rabbit models induced by fibrin and the effects of an angiotensin converting enzyme inhibitor (enalaprilat) on NPE. NPE models were induced by intracisternal injection of fibrinogen and thrombin. According to random number table method, 18 healthy adult New Zealand rabbits were assigned to three groups (with 6 in each) : normal control group (Con group), NPE group and enalaprilat treated (Ena) group. After establishment of NPE models, rabbits in Ena group were given intravenous enalaprilat 0.5 mg/kg. Expression of ACE,ACE2,AT1R mRNA of the lung tissue were evaluated by real-time polymerise chain reaction; and Ang II of the lung tissue was determined by enzyme linked immunosorbent assay ( ELISA ). Meanwhile, histopathological lung injury scores were evaluated. ACE mRNA expression level in NPE group ( 17.2 ± 3.3) appeared an increasing trend in contrast to Con group ( 12.6 ± 5.2 ) and Ena group ( 11.5 ± 2.4, both P > 0.05 ). Compared with Con group (81 ± 22 ), ACE2 mRNA expression levels of NPE group ( 52 ± 6 ) and Ena group ( 45 ± 13 ) both decreased ( both P < 0.05 ) . ACE mRNA/ACE2 mRNA expression levels of NPE group ( 0.33 ± 0.06 ) and Ena group ( 0.26 ± 0.04 ) were higher than those of Con group ( 0.16 ± 0.05, both P < 0.05 ), as well as the ratio of Ena group decreased compared with untreated NPE group ( 0.26 ± 0.04 vs. 0.33 ± 0.06, P < 0.05 ) . There were no statistically significant differences in expression of AT1 mRNA of the lung tissue among three groups, but Ena group ( 4.8 ± 1.1) in contrast to NPE group ( 6.7 ± 1.3) has no significant difference (P > 0.05). Lung AngII level of NPE group [(540 ± 147) pg/ml] was significantly higher than that of Con group [(253 ± 37 ) pg/ml] and Ena group [(309 ± 35 ) pg/ml, both P < 0.05 ]. Gross pathologic examination showed that pink foamy edema fluid appeared in the tracheal tubes in NPE group, but spontaneously appeared in neither Con group nor Ena group; and the level of pulmonary subpleural bleeding in Con group, 12 graded 0; in NPE group, 2 graded II, 10 graded III; in Ena group, 2 graded, 8 grade II, 2 grade III. The histopathologic lung injury scores in Ena group was decreased in contrast to NPE group (1.36 ± 0.26 vs.2.32 ± 0.49, P < 0.05) and mainly for the improvement of alveolar overdistension and interstitial edema. The present study showed that when NPE occurs, a high lung AngII concentration was associated with an imbalance between ACE mRNA to ACE2 mRNA expression level. Activated local RAS in lung tissue resulted in lung injury. Enalaprilat treatment may attenuate lung injury by interventing local RAS in lung tissue with decreased ratio of ACE mRNA to ACE2 mRNA and lung AngII concentration. The result will be significant for the angiotensin converting enzyme inhibitor used in the theatment of NPE.

Angiotensin behaves like a paracrine mediator in guinea pig enteric nervous system (874.1)

Enteric mast cell hyperplasia occurs in inflammatory bowel disease and the irritable bowel syndrome. Mast cell proteases are catalysts for conversion of angiotensin I to angiotensin II (AT‐II). We applied AT‐II to ENS neurons, while recording neuronal electrical and synaptic behavior. The AT‐II acted to elevate or suppress neuronal excitability. Suppression of was reversed by noradrenergic alpha2 receptor blocking drugs. AT‐II enhanced electrically‐evoked noradrenergic inhibitory postsynaptic potentials and suppressed fast and slow excitatory postsynaptic potentials. Selective AT‐II1 receptor blocking drugs, but not selective AT2 receptor antagonists, suppressed all actions of AT‐II. AT2 receptor protein and the AT2 mRNA transcript were expressed in the ENS. The AT1 receptor was not expressed. Immunoreactivity for the AT1 receptor was expressed by ENS neurons with AH‐type 2 and S‐type electrophysiological behavior. Our results predict that mast cell‐induced AT‐II formation will have paracrine function in the ENS that includes enhanced release of norepinephrine from sympathetic postganglionic axons. Elevation of norepinephrine represses excitatory neurotransmission in the neural networks of the brain‐in‐the‐gut and suppresses neurogenic secretion thru inhibition of excitability of secretomotor neurons in the submucosal division of the ENS.Grant Funding Source: Supported by National Institutes of Health, R01DK037238

Relationship between renal injury and the antagonistic roles of angiotensin-converting enzyme (ACE) and ACE2.

Angiotensin-converting enzyme 2 (ACE2), a newly discovered carboxypeptidase in the renin-angiotensin system (RAS), antagonizes ACE activity and plays an active role during tissue injury. Yet the mechanism of its action is not well known. Using a streptozotocin (STZ)-induced renal injury rat model, we investigated the relationship between renal injury and the antagonism between ACE and ACE2. We assayed the levels of urea nitrogen, urine glucose, creatinine, and protein, Ace2, Ace, angiotensin II type 1 receptor (At1) and Mas receptor mRNA, and renal and plasma angiotensin II (Ang II) in STZ-treated and untreated rats. We also used histology and immunohistochemistry to assess glomerular injury and ACE2 glomerular and cortical expression. The amounts of urea nitrogen, urine glucose, creatinine, and protein were significantly higher in STZ-treated rats than in control rats (P < 0.01). There were significant pathological changes in the kidney upon STZ-treatment. Ace2 and Ace mRNA levels were significantly higher in STZ-treated rats than in control rats (P < 0.05 and P = 0.05, respectively). There was no significant difference in the Mas receptor and At1 mRNA levels in the 2 groups, although At1 levels showed an increase upon STZ-treatment. The Ang II level in the renal cortical tissue and plasma of STZ-treated rats was higher than that of control rats (P < 0.05). The increase in Ace mRNA levels was higher than that of Ace2 mRNA levels, leading to an elevated Ace/Ace2 ratio. Together, these data suggest that the ACE-Ang II-AT1 axis is the dominant axis in severe kidney injury.

Effect of angiotensin II infusion on rhythmic clock gene expression and local renin-angiotensin system in the aorta of Wistar rats.

Endogenous daily rhythms in physiology are regulated by the circadian system consisting of the central and peripheral components. The renin-angiotensin system, involved predominantly in water balance and blood pressure control, exerts 24 h rhythmicity in many of its parameters. The present study is aimed to study possible interactions between these two control systems. We analyzed effects induced by angiotensin II administration on clock gene expression in the aorta of rat and an ability of angiotensin II to influence the local tissue renin-angiotensin system. Angiotensin II was infused in a dose of 100 ng/kg/min by subcutaneously implanted osmotic minipumps for 28 days to male Wistar rats. Gene expression was measured by real time PCR. Angiotensin II administration resulted in an increase in blood pressure, heart weight/body weight index, and water intake in comparison with controls. We observed a significant phase advance in per2 and npas2 mRNA rhythms and decreased mesor of npas2 rhythmic expression in the aorta of angiotensin II-treated rats compared to control. Angiotensin II administration did not influence daily pattern and level of at1 mRNA expression. The ratio ace/ace2 showed a rhythmic pattern in the aorta of control rats with peak levels in the dark period. Angiotensin II infusion influenced clock gene expression and diminished a daily rhythm in ace/ace2 mRNA ratio indicating modulatory effect of angiotensin II on tissue renin-angiotensin system in the aorta.

The role of estradiol in adrenal insufficiency and its interaction with corticosterone on hydromineral balance

Estradiol (E2) plays an important role in controlling the homeostasis of body fluids. Several studies have reported the involvement of the hypothalamic pituitary adrenal axis (HPA) in the homeostatic control of hydromineral balance and the influence of estrogens on the modulation of this system. Nevertheless, until now, the physiological relevance of HPA axis activity on the hydromineral balance in females has not yet been fully elucidated. Therefore, the objective of the present study was to evaluate the effects of E2 (20μg/animal) pretreatment on neuroendocrine and hydroelectrolyte changes induced by adrenalectomy (ADX) with or without glucocorticoid hormone replacement (corticosterone, CORT; 10mg/kg) in ovariectomized rats (OVX). The results show that sodium appetite, natriuresis and the elevated plasma angiotensin II (ANG II) concentration induced by ADX were attenuated by E2 pretreatment. Additionally, a reduction of AT1 mRNA expression in the subfornical organ (SFO) and an increase in plasma atrial natriuretic peptide (ANP) concentrations by E2 pretreatment were observed. E2 pretreatment reversed the reduction in water intake induced by ADX in ADX CORT-replaced rats. Moreover, E2 pretreatment attenuated corticotropin releasing factor (CRF) mRNA expression in the paraventricular nucleus (PVN) induced by ADX. In contrast, E2 pretreatment increased CRF mRNA expression in the PVN in ADX CORT-replaced rats. Taken together, these results suggest that E2 has an important role in the modulation of behavioral and neuroendocrine responses involved in the maintenance of body fluid homeostasis in ADX rats with or without glucocorticoid replacement therapy.

Expression and significance of ACE2-Ang-(1-7)-Mas axis in the endometrium of patients with polycystic ovary syndrome

To explore the expression of renin-angiotensin system component (ACE-AngII-AT1/AT2 & ACE2-Ang-(1-7)-Mas) in endometrium of polycystic ovary syndrome (PCOS) patients and normal controls. Thirty cases of normal endometrium in proliferative and secretory phases respectively were selected for the protein levels of AngII, AT1, AT2, ACE2, Ang-(1-7) and Mas through immunohistochemistry. And the specimens of proliferative endometrium from 15 PCOS patients and 15 normal controls respectively were prepared for the expressions of AT1, AT2, ACE2 and Mas mRNA through relative quantitative -polymerase chain reaction (RQ-PCR). The histological phases of endometria were confirmed by hematoxylin & eosin staining under microscope. The expressions of AngII, AT1R, AT2R, ACE2, Ang-(1-7) and Mas showed periodical changes in endometrium throughout normal menstrual cycles and shared a similar trend. The expression was more pronounced in epithelial cells than that in stromal cells while it was also more dramatic in secretory phase than proliferative phase; The mRNA expressions of AT1, AT2, ACE2 and MAS were higher in PCOS endometrium than those in normal controls. Statistically significant differences existed between two groups (P < 0.01). There is local existence of RAS in endometrium; Increased expressions of AT1 mRNA, AT2 mRNA, ACE2 mRNA and Mas mRNA in endometrium of PCOS may influence endometrial development and play a role in the pathological process of PCOS.

Chemotherapy and radiation regimens to breast cancer treatment induce changes in mRNA levels of renin–angiotensin system related genes in cardiac tissue

Cardiovascular complications are one limitation of breast cancer treatment. The aim of the current study was to investigate whether the renin-angiotensin related genes could be altered by chemotherapy and radiotherapy, using a rat model. Female rats were divided into three groups: control, chemotherapy + irradiation (TC+IR) and irradiation (IR). Molecular analyses of the left ventricle were performed five months after the end of treatment. The analyses evaluated the changes in mRNA levels of some renin-angiotensin system (RAS) related genes: angiotensinogen, renin, angiotensin-converting enzyme (ACE) and angiotensin II type 1 receptor (AT1) and vascular endothelial growth factor (VEGF), which can be related to ACE production, by RT-PCR. Renin was only observed in treated groups, TC+IR and IR, compared with the control group. ACE and VEGF levels were decreased in TC+IR (p<0.001) and in IR (p<0.001), and AT1 mRNA was higher in groups TC+IR (p<0.01) and IR (p<0.05) compared with the control group. Chemotherapy and irradiation can induce significant changes in some RAS related genes. These alterations are important to understand the pathways and consequences beyond cardiotoxicity induced by breast cancer treatments.

Retracted: Expression of angiotensin II and its receptors in cyclosporine‐induced gingival overgrowth

The renin-angiotensin system (RAS) is considered as a hormonal circulatory system involved in maintaining blood pressure, electrolyte and fluid homeostasis. RAS components can be synthesized in local tissues and are found to play a role in gingival overgrowth. The drug-induced gingival overgrowth (DIGO) is a fibrotic condition, which is associated with multiple factors, including inflammation and adverse drug effects such as cyclosporine A. This study was directed forward to the identification of the angiotensinogen, angiotensin II (Ang II) and its receptors AT₁ /AT₂ expression in DIGO tissues and cyclosporine-treated human gingival fibroblast cells. Gingival samples were obtained from patients with cyclosporine-induced gingival overgrowth, chronic periodontitis and normal healthy subjects. The total RNA was isolated and reverse transcription-polymerase chain reaction was performed for angiotensinogen, Ang II and AT₁ /AT₂ receptor. Ang II protein was estimated from tissue by enzyme immunoassay. The expression of Ang II and its receptors were also examined in gingival fibroblast cells treated with cyclosporine. Ang II mRNA and protein expression was significantly higher in patients with DIGO than in patients with periodontitis and healthy subjects. The AT₁ mRNA was expressed more than AT₂ in all examined tissues. In gingival fibroblasts, Ang II and AT₁ expressions were increased with cyclosporine incorporation compared to controls. These results suggest that cyclosporine can modulate local expression of RAS components such as angiotensinogen, Ang II and its receptors in gingival tissues and gingival fibroblast cells.

The levels of renin–angiotensin related components are modified in the hippocampus of rats submitted to pilocarpine model of epilepsy

We previously showed that patients with temporal lobe epilepsy (TLE) present an increased expression of angiotensin II (AngII) AT1 and AT2 receptors in the hippocampus, supporting the idea of an upregulation of renin–angiotensin system (RAS) in this disease.This study aimed to verify the relationship between the RAS and TLE during epileptogenesis. Levels of the peptides angiotensin I (AngI), angiotensin II (AngII) and angiotensin 1–7 (Ang 1–7), were detected by HPLC assay. Angiotensin AT1 and AT2 receptors, Mas mRNA receptors and angiotensin converting enzyme (ACE), tonin and neutral endopeptidase (NEP) mRNA were also quantified at the hippocampus of Wistar rats by real time PCR, during acute (n=10), silent (n=10) and chronic (n=10) phases of pilocarpine-induced epilepsy.We observed an increased peptide level of Ang1–7 into acute and silent phases, decreasing importantly (p⩽0.05) in the chronic phase, suggesting that AngI may be converted into Ang 1–7 by NEP, which is present in high levels in these periods.Our results also showed increased peptide level of AngII in the chronic phase of this model. In contraposition, the ACE expression is reduced in all periods. These data suggest that angiotensinogen or AngI may be cleaved to AngII by tonin, which showed increased expression in all phases. We found changes in AT1, AT2 and Mas mRNA receptors levels suggesting that Ang1–7 could act at Mas receptor during the silent period. Herein, we demonstrated for the first time, changes in angiotensin-related peptides, their receptors as well as the releasing enzymes in the hippocampus of rats during pilocarpine-induced epilepsy.

Nephron-specific expression of components of the renin–angiotensin–aldosterone system in the mouse kidney

The renin-angiotensin-aldosterone system (RAAS) plays an integral role in the regulation of blood pressure, electrolyte and fluid homeostasis in mammals. The capability of the different nephron segments to form components of the RAAS is only partially known. This study therefore aimed to characterize the nephron-specific expression of RAAS components within the mouse kidney. Defined nephron segments of adult C57B/16 mice were microdissected after collagenase digestion. The gene expression of renin, angiotensinogen (AGT), angiotensin-converting enzyme (ACE), angiotensin II receptors 1a (AT1a), 1b (AT1b), and 2 (AT2) was assessed by reverse transcriptase polymerase chain reaction (RT-PCR). Renin mRNA was present in glomeruli, in proximal tubules, in distal convoluted tubules (DCT) and cortical collecting ducts (CCD). AGT mRNA was found in proximal tubules, descending thin limb of Henle's loop (dTL) and in the medullary part of the thick ascending limb (mTAL). ACE mRNA was not detectable in microdissected mouse nephron segments. AT1a, AT1b and AT2 mRNA was detected in glomeruli and proximal convoluted tubules. Our data demonstrate a nephron-specific distribution of RAAS components. All components of the local RAAS - except ACE - are present in proximal convoluted tubules, emphasizing their involvement in sodium and water handling.

Telmisartan ameliorates lipopolysaccharide-induced innate immune response through peroxisome proliferator-activated receptor-γ activation in human monocytes

Angiotensin II type 1 receptor (AT1) blockers (ARBs) reduce the bacterial endotoxin lipopolysaccharide (LPS)-induced innate immune response in human circulating monocytes expressing few AT1. To clarify the mechanisms of anti-inflammatory effects of ARBs with different peroxisome proliferator-activated receptor-γ (PPARγ)-activating potencies, we focused our study on telmisartan, an ARB with the highest PPARγ-stimulating activity. Human circulating monocytes and monocytic THP-1 (human acute monocytic leukemia cell line) cells were exposed to 50 ng/ml LPS with or without pre-incubation with telmisartan. AT1 mRNA and protein expressions were determined by real-time PCR and membrane receptor binding assay, respectively. The expression of pro-inflammatory factors was determined by real-time PCR, western blot analysis and ELISA. PPARγ activation was measured by electrophoretic mobility shift assay and its role was determined by pharmacological inhibition and PPARγ gene silencing. In human monocytes, telmisartan significantly attenuated the LPS-induced expression of pro-inflammatory factors, the release of pro-inflammatory cytokines and prostaglandin E2, nuclear factor-κB activation and reactive oxygen species formation. In THP-1 cells, telmisartan significantly reduced LPS-induced tumor necrosis factor-α, inhibitor of κB-α, monocyte chemotactic protein-1 (MCP-1) and lectin-like oxidized low-density lipoprotein receptor-1 gene expression and MCP-1-directed migration. Telmisartan also stimulated the expression of the PPARγ target genes cluster of differentiation 36 and ATP-binding cassette subfamily G member 1 in monocytes. The anti-inflammatory effects of telmisartan were prevented by both PPARγ antagonism and PPARγ gene silencing. Anti-inflammatory effects of ARBs correlated with their PPARγ agonist potency. Our observations demonstrate that in human monocytes, ARBs inhibit the LPS-induced pro-inflammatory response to a major extent through the PPARγ activation pathway and may be beneficial for the treatment of cardiovascular and metabolic disorders in which inflammation plays a major role.

Evaluation of the brain and kidney renin-angiotensin system and oxidative stress in neonatal handled rats

The aim of this study was to test the hypothesis that the renin-angiotensin system (RAS) components, as well as the oxidative stress system, would respond to early environmental changes. Thus, we have evaluated the effects of neonatal handling on both brain and kidney RAS and oxidative stress. Pups were divided into two groups: nonhandled and handled. The procedure consisted of handling them for 1 min/day in the first 10 days of life. On days 1, 5, and 10, animals were killed by decapitation. Blood samples were collected and the brain and kidneys were removed. Renin, AT(1), and AT(2) mRNA expression were evaluated through RT-PCR. Angiotensin II (ANG II) serum concentration was also measured. An increased ANG II concentration, brain and kidney AT(2) mRNA expression were demonstrated. The kidney mRNA AT(1) expression was decreased. There was also a kidney lipid peroxidation increase and a brain superoxide dismutase and catalase decrease. In conclusion, handling in the neonatal period induces the activation of the angiotensinergic system, as well as modulates its mRNA receptor expression. The oxidative stress balance system seems not to be involved.

The relationship between gene expression of cationic and neutral amino acid transporters in the small intestine of chick embryos and chick breed, development, sex, and egg amino acid concentration

This study was conducted to investigate the gene expression of cationic and neutral amino acid (AA) transporters in the small intestine of chick embryos with different genetic backgrounds [Wenshi Yellow-Feathered chick (WYFC) and White Recessive Rock chick (WRRC)]. The study also investigated the correlation between the abundance of AA transporter mRNA and the AA content of fertilized eggs. Intestinal samples were collected on embryonic d 9, 12, 14, 17, and 19 and the day of hatch. The results showed that, before incubation, the AA content of WRRC eggs was lower (P < 0.05) than the AA content of WYFC eggs. In WYFC, the mRNA abundance of CAT-1 [solute carrier (SLC) family 7 member 1], CAT-4 (SLC family 7 member 4), rBAT (SLC family 3 member 1), y(+)LAT-1 (SLC family 7 member 7), y(+)LAT-2 (SLC family 7 member 6), LAT-4 (SLC family 43 member 2), and SNAT-2 (SLC family 38 member 2), as detected by real-time reverse transcriptase PCR, was greater (P < 0.05) than the mRNA abundance detected in the WRRC samples. The mRNA abundance of all measured AA transporters was affected (P < 0.05) by embryonic age. Sex had the largest effect (P < 0.05) on the mRNA expression of CAT-1, CAT-4, y(+)LAT-2, and LAT-4 in WYFC and on CAT-4 and B(0)AT-1 (SLC family 6 member 19) mRNA expression in WRRC. In WYFC, only CAT-1 mRNA expression was negatively correlated (r = -0.68 to -0.84, P < 0.05) with all AA content. However, few correlations were detected between AA content and the mRNA expression of multiple transporters in WRRC. These findings provide a comprehensive profile of the temporal and spatial mRNA expression of AA transporters in the small intestine of chick embryos. Few correlations were detected between the AA content of the eggs and mRNA expression of specific AA transporters in the small intestine.

Effects of Pioglitazone on High-Fat-Diet–Induced Ventricular Remodeling and Dysfunction in Rats

To investigate the effect of pioglitazone on high-fat (HF)-diet-induced left ventricular (LV) hypertrophy and dysfunction in rats. A total of 36 male Sprague-Dawley rats were randomly divided into 3 groups, namely, control, HF diet, and pioglitazone treatment group. High-fat diet group (HF group) animals were treated with HF diet for 30 weeks, whereas pioglitazone group was treated with HF diet for 30 weeks and pioglitazone in the last 6 weeks of the 30-week treatment. Fasting plasma free fatty acids (FFAs), serum, and myocardial triglyceride were measured. Left ventricular function was assessed by echocardiography. Renin, angiotensin II, and angiotensin types 1 and 2 (AT1/AT2) receptors in the myocardium were analyzed by immunohistochemistry and real-time polymerase chain reaction (PCR). Systolic blood pressure, plasma FFA, serum, and myocardial triglyceride concentrations in HF group were higher than in control and pioglitazone groups (P < .01). There was no significant difference in LV weight index and LV posterior wall thickness between HF and pioglitazone groups; both were higher than in the control group (P < .01). Left ventricular ejection fraction, fraction of shortening, and cardiac index in HF group were lower than in the control and pioglitazone groups (P < .05). Myocardial expression of angiotensin II and AT1 receptor protein in HF group was higher when compared with the control and pioglitazone groups (P < .01). Myocardial renin and angiotensin II messenger RNA (mRNA) in HF group was also higher when compared with the control and pioglitazone groups, whereas the expression of AT2 mRNA was lower (P < .01). Pioglitazone diminished HF-diet-induced LV dysfunction. These effects may be related to a reduction in blood pressure, myocardial triglycerides sedimentary, and suppression of renin-angiotensin system.

Angiotensin II does not acutely regulate conduction velocity in rat atrial tissue

Aim. Atrial angiotensin II (Ang II) levels are increased in atrial fibrillation and are believed to be important in the pathogenesis of atrial arrhythmias. Ang II reduces intercellular coupling by inhibiting gap junctions (connexins) and may thereby increase the risk of reentry arrhythmia. The aim of the current study was to investigate the acute effect of Ang II on conduction velocity (CV) in atrial tissue from normal and chronically infarcted rats. Methods. Contractile force was measured and CV was determined from the conduction time between electrodes placed on the tissue preparation. Expression of AT1a and AT1b receptors was examined by real-time PCR. Results. Acute stimulation with Ang II did not affect CV in tissue from auricle or atrial free wall. A transient 6.5 ± 3.6% increase in resting tension was observed in atrial free wall preparations, indicating that receptors are present and functional in the free wall preparation. The difference between free wall and auricle was probably not caused by differences in receptor expression since equal amounts of AT1 mRNA were present. To test if myocardial infarction (MI) sensitizes the atrium to Ang II, free atrial wall from rats subjected to 4–5 weeks ventricular MI was examined. Although CV was significantly reduced by MI, no effect on CV of Ang II was seen. Conclusion. Ang II does not acutely regulate CV in tissue preparations from the free wall of the left atria or the left auricle. Although ventricular MI reduces CV, this does not sensitize the atria to Ang II.

Telmisartan protects against insulin resistance by attenuating inflammatory response in rats

This study investigated the effects of telmisartan on insulin resistance in high-fat diet-treated rats and the possible mechanism. A total of 40 male Sprague-Dawley rats enrolled in the study were divided into 4 groups at random: ND group (n=10) and HD group (n=10), in which the rats were given a normal chow diet or a high-fat diet for 20 weeks following a one-week adaptation; ND+telmisartan (n=10) group and HD+telmisartan group (n=10), in which the rats were initially administered in the same way as the ND or HD group, and then they were orally gavaged with telmisartan (5 mg/kg daily) additionally for 5 weeks. Related inflammatory factors were measured by ELISA. Monocyte chemotactic protein 1 (MCP-1), phosphorylated JNK and IκB-α expressions in both adipose and liver were detected by Western blotting. CRP and angiotensin II receptor 1 (AT1) mRNA expressions in both adipose and liver were determined by RT-PCR. The results showed that telmisartan administration in vivo reversed insulin resistance as evidenced by a decrease in plasma fasting glucose levels, plasma fasting insulin levels and homeostasis model of assessment-insulin resistance (HOMA-IR). Furthermore, telmisartan administration significantly reduced serum CRP, TNF-α and IL-1β levels, and elevated serum IL-10 levels. It was also found to hamper the high-fat diet-induced increase in CRP mRNA, AT1 mRNA and MCP-1, and decrease in IκB-α in both adipose and liver. It was concluded that telmisartan administration in vivo may improve insulin resistance through attenuated inflammatory response pathways.