Protective Effect Of Irbesartan Research Articles

Protective effect of irbesartan against hepatic ischemia-reperfusion injury in rats: role of ERK, STAT3, and PPAR-γ inflammatory pathways in rats.

This study aimed to elucidate the possible hepatocellular protective role of irbesartan during hepatic ischemia-reperfusion injury (HIRI) and the probable underlying mechanisms. Wistar rats were allocated into four groups: sham; HIRI (control); irbesartan (50 mg/kg) + HIRI; irbesartan (100 mg/kg) + HIRI; irbesartan + GW9662 (1 mg/kg, i.p.) + HIRI. Rats pretreated orally with irbesartan or vehicle for 14 days underwent 45-min hepatic ischemia followed by 60-min reperfusion. Irbesartan preconditioning diminished alanine transaminase (ALT) and aspartate transaminase (AST) serum levels, and reduced extracellular signal-regulated kinase (ERK) and signal transducer and activator of transcription 3 (STAT3). Irbesartan decreased proapoptotic BAX (bcl-2-like protein 4), increased anti-apoptotic B-cell lymphoma 2 (BCL2) hepatic content, and thereby reduced BAX/BCL2 ratio. Moreover, irbesartan preconditioning reduced autophagy-related proteins Beclin1 and LC3 II, and elevated p62 (protein responsible for autophagosome degradation). It elevated proliferator-activated receptor γ (PPAR-γ), and reduced tumor necrosis factor-alpha (TNF-α) and interleukin-6 (IL-6) hepatic gene expression. Also, hepatic protein expressions of nuclear factor kappa-B p65 (NF-κB p65) and caspase-3 were lessoned by irbesartan pretreatment in HIRI rats. However, GW9662 abrogated irbesartan's effect on HIRI. The protective effect of irbesartan on HIRI may be mediated by alleviation of ERK, STAT3, and PPAR-γ inflammatory pathways, exerting anti-apoptotic and anti-autophagic effects in HIRI in rats.

The protective effects of Irbesartan in cognitive impairment in hypertension.

Vascular cognitive impairment (VCI) is claimed as the second most common type of dementia after Alzheimer's disease (AD), in which hypertension is a critical inducer. Currently, hypertension-induced cognitive impairment lacks clinical treatments. Irbesartan is a long-acting angiotensin receptor antagonist with promising antihypertensive properties. Our research will focus on the potential function of Irbesartan on hypertension-induced cognitive impairment. Wistar-Kyoto (WKY) and spontaneously hypertensive (SHR) rats were orally dosed with normal saline or 20 mg/kg/day Irbesartan for 14 consecutive days, with 4 groups divided shown as below: WKY, Irbesartan, SHR, SHR+ Irbesartan. Firstly, the markedly increased systolic blood pressure observed in SHR rats was signally repressed by Irbesartan on Day 7 and 14 post-dosing. Moreover, notably decreased time of exploring the novel object in the object recognition task (ORT) test, elevated escape latency, and reduced time in the target quadrant in the Morris water maze (MWM) test were observed in SHR rats, which were prominently reversed by Irbesartan. Furthermore, the declined superoxide dismutase (SOD) activity, elevated malondialdehyde (MDA) level, increased cyclin-dependent kinase-5 (CDK5) activity, and enhanced protein level of p35/p25, p-Tau (pSer214)/Tau46, and brain-derived neurotrophic factor (BDNF) were memorably rescued by Irbesartan. Lastly, the activity of cAMP/cAMP response element binding protein (CREB) signaling in the hippocampus of SHR rats was markedly repressed, accompanied by an upregulation of phosphodiesterase 4B (PDE4B), which was observably rescued by Irbesartan. Collectively, Irbesartan protected against the hypertension-induced cognitive impairment in SHR rats by regulating the cAMP/CREB signaling.

IRBESARTAN REDUCES LIVER DAMAGE INDUCED BY LIPOPOLYSACCHARIDE VIA INHIBITION OF TOTAL OXIDANT STATUS, INTERLEUKIN-1B AND CASPASE-3 LEVELS

Objective
 In septic conditions, hyperinflammatory response
 and hepatotoxicity are caused by oxidative stress,
 inflammation, and apoptosis. Irbesartan (IB), an
 adrenergic receptor blocker, has anti-inflammatory and
 antioxidant properties. This study aimed to investigate
 the protective effect of IB on lipopolysaccharide (LPS)-
 induced acute hepatotoxicity.
 Material and Method
 A total of eight rats were used in three groups; a control
 group; LPS group [5 mg/kg, intraperitoneally (IP)];
 and LPS + IB group [5 mg/kg LPS (IP) + 50 mg/kg IB
 (orally)]. After sacrification, tissues from the liver and
 blood were obtained for immunohistochemical and
 biochemical evaluations, such as interleukin-1 beta
 (IL-1β), caspase-3 (Cas-3) alanine aminotransferase
 (ALT), aspartate aminotransferase (AST), oxidative
 stress index (OSI), total oxidant status (TOS), and
 total antioxidant status (TAS).
 Results
 Compared with the control group, increased AST
 and ALT levels in the blood, biochemically increased
 TOS and OSI and decreased TAS levels in the
 tissue, immunohistochemically increased IL-1β, Cas-
 3, detected. Also, in liver tissue, histopathologically
 hyperemia, hemorrhage, vacuolization, and
 significant neutrophilia infiltration were found in the
 LPS group. IB administration significantly reversed
 all these parameters. TAS levels were increased
 by IB administration, whereas TOS and OSI levels
 were decreased (p = 0.001). IB also decreased
 AST and ALT values (p = 0.001). In the IB group,
 Cas-3 and IL-1β levels were significantly decreased
 by IB administration (p = 0.001). In addition, the
 IB ameliorated histopathological findings showed
 enhanced hyperaemia, haemorrhages, vacuolisation
 and significant neutrophilic leukocyte infiltration
 (p = 0.001). IB treatment attenuated LPS-induced
 hepatotoxicity by its antioxidant, anti-inflammatory and
 antiapoptotic properties.
 Conclusion
 Attenuating liver injury and restoring liver function lowers
 morbidity and mortality rates in patients with sepsis.
 IB protects liver tissue from hepatotoxicity caused by
 LPS thanks to its antioxidant, anti-inflammatory, and
 anti-apoptotic properties. Further investigation of the
 liver’s role in sepsis may lead to the development of
 new therapeutic targets and strategies. IB may be
 an alternative therapeutic agent for the prevention of
 acute hepatotoxicity during sepsis.

Irbesartan protects against type 2 diabetic nephropathy by regulating miR-93/VEGF and its downstream effectors

Purpose: To investigate the protective effect of irbesartan against type 2 diabetic nephropathy (T2DN), and the mechanism involved.Methods: Wistar rats (n = 48) were used in this study. Diabetes mellitus (DM) was established in the rats via injection of streptozotocin (STZ). Thereafter, the DM rats were randomly divided into diabetic nephropathy (DN) group and irbesartan group, with 16 rats in each group. Rats in the control group (n = 16) received normal saline in place of irbesartan.Results: Total cholesterol (TC), triglycerides (TGs), high-density lipoprotein cholesterol (HDL-C) and low-density lipoprotein cholesterol (LDL-C), as well as protein expression levels of VEGF, FN, collagen IV in DN group were significantly higher in irbesartan group than the corresponding levels in normal control group, while miR-93 protein expression level was significantly lower than that in normal control group (p < 0.05). However, the expression level of mir-93 was significantly higher in irbesartan group than in DN group, while levels of TC, TGs, HDL-C, LDL-C and VEGF, as well as protein levels of FN and collagen IV protein were significantly lower than those in DN group (p < 0.05). There was no obvious change in the renal tissues of the normal control group. In contrast, in the DN group, glomerularcapillary loop hypertrophy, narrow glomerular cavity, thick basement membrane, mesangial matrix, and vacuolar degeneration in renal tubular epithelial cells, were evident. Compared with DN group, the pathological changes in the irbesartan group were significantly mitigated (p < 0.05).Conclusion: Irbesartan protects DM rats against type 2 diabetic nephropathy by regulating mir-93/VEGF and its downstream effector molecules. This provides some ideas for the development of new drugs for the prevention of type 2 diabetic nephropathy.

Protective Effects of Irbesartan, an Angiotensin Receptor Blocker with PPARγ Agonistic Activity, against Estradiol Benzoate-Induced Endometrial Hyperplasia and Atypia in Female Rats via Modulation of TNFα/Survivin Pathway.

Endometrial hyperplasia (EH) is a common gynecological problem and may progress to carcinoma. Early detection and management of EH are mandatory for the prevention of endometrial cancer. Activation of the renin–angiotensin system and angiotensin II signaling are involved in the progression of precancerous and cancerous lesions. However, no studies have evaluated the role of this system in estradiol benzoate (EB)-induced EH and atypia. Irbesartan (IRB), an angiotensin II receptor blocker with peroxisome proliferator-activated receptor gamma (PPARγ) agonistic activity was administered (30 mg/kg/d) in EB-treated (60 µg/100 g bodyweight, intramuscularly, three times per week) or untreated rats for 4 weeks. Uterine weight changes, malondialdehyde, superoxide dismutase (SOD), tumor necrosis factor-alpha (TNFα), survivin, cleaved caspase 3, interleukin-10 (IL10), and PPARγ were measured in addition to undergoing histopathological examination. Results showed that EB-induced EH and atypia significantly increased the uterine body weight, malondialdehyde, TNFα, and survivin, accompanied with significantly decreased SOD, cleaved caspase 3, IL10, and PPARγ, with typical histopathological changes of EH and atypia. Coadministration of IRB significantly prevented EB-induced biochemical and histopathological changes. The protective effects of IRB may be attributed to its anti-inflammatory and antioxidant properties, reduction of survivin, and increased levels of cleaved caspase 3.

Irbesartan suppresses lipopolysaccharide (LPS)-induced blood–brain barrier (BBB) dysfunction by inhibiting the activation of MLCK/MLC

The basic function of the blood–brain barrier (BBB) is to selectively regulate the infiltration of solutes from the circulating blood into the central nervous system (CNS). Impaired BBB activity is related to brain damage caused by stroke, traumatic injury, neurodegenerative diseases, etc. Comprised of a monolayer of endothelial cells, the integrity of the BBB is determined by the expression of tight junction proteins and the contractile activity of the perijunctional apical actomyosin ring. Irbesartan, an AT1R antagonist, has been widely used for the treatment of hypertension. However, the pharmacological function of Irbesartan in the balance of the BBB is still unknown. In the present study, we performed both in-vivo and in-vitro experiments using lipopolysaccharide (LPS) to explore the mechanism behind the protective effects of Irbesartan against the BBB impairment. The results of our mouse model study revealed that Irbesartan could reduce BBB permeability, restore the expression of Occludin, and suppress the expression of inflammatory mediators, including interleukin-6, monocyte chemoattractant protein-1, and intercellular adhesion molecule-1. Additionally, Irbesartan improved LPS-induced depressive-like behavior. In our in vitro experiments, human brain microvascular endothelial cells (HBMVECs) stimulated with LPS demonstrated decreased endothelial permeability and increased occludin expression in response to Irbesartan treatment. Importantly, we found that the protective effects of Irbesartan were mediated through the NF-κB/MLC/MLCK signaling pathway, as blockage of NF-κB abolished the effects of Irbesartan. Our findings provide a basis for further research into the neuroprotective mechanism of Irbesartan.

Protective effects of irbesartan and benazepril against vaginal vascular remodeling and fibrosis in female spontaneously hypertensive rats.

ObjectiveTo compare the potential beneficial effects of the angiotensin converting enzyme inhibitor (ACEI) benazepril and the angiotensin II receptor 1 blocker (ARB) irbesartan on vaginal vascular remodeling and fibrosis in female spontaneously hypertensive rats (SHRs).MethodsTwelve-week-old female SHRs were treated with irbesartan or benazepril for 12 weeks. Vaginal renin angiotensin system (RAS) components were detected by polymerase chain reaction and western blot and vaginal α-smooth muscle actin (α-SMA), endothelial nitric oxide synthase (eNOS), and collagen III (Col III) were analyzed by western blot. Vaginal tissue sections were examined by hematoxylin and eosin staining, Masson trichrome staining, and immunohistochemical analysis of α-SMA and Col III.ResultsIrbesartan and benazepril had different impacts on vaginal RAS components. Both agents decreased vaginal α-SMA and Col III and increased eNOS expression in SHR. The wall/lumen thickness ratio of vaginal arterioles was similarly decreased following irbesartan and benazepril treatment. Both drugs also decreased collagen deposition in SHRs. There was no difference in vaginal vascular remodeling or fibrosis between the two groups.ConclusionsIrbesartan and benazepril have different effects on vaginal RAS expression but similar positive effects against vaginal vascular remodeling and fibrosis.

Irbesartan suppresses cardiac toxicity induced by doxorubicin via regulating the p38-MAPK/NF-κB and TGF-β1 pathways.

Doxorubicin (DOX) so far continues to be one of the most potent and effective anticancer drugs. Therefore, it is still needed to search for a safe and effective therapy that can opposite DOX-induced cardiotoxicity. Irbesartan (IRB), an angiotensin II receptor blocker, has a wide-ranging variety of biological activities. The present study was designed to explore the possible protective effects of IRB against DOX-induced cardiotoxicity and the underlying mechanisms. Rats were divided into four groups: control, IRB (40mg/kg, orally/daily) for 3weeks, DOX (2.5mg/kg, intraperitoneally/ three times weekly) for 2weeks to obtain cumulative dose of 15mg/kg, and finally IRB + DOX group. IRB inhibited cardiotoxicity induced by DOX which was evident by ECG changes, alterations of cardiac enzymes and histopathological changes. IRB improved DOX-induced alterations in oxidative/nitrosative status by decreasing lipid peroxidation and nitric oxide (NO) content in addition to increasing the antioxidant capacity. In addition, DOX triggers the cardiac expression of tumor necrosis factor-α (TNF-α) and nuclear factor kappa B (NF-κB) where IRB diminished DOX-induced alterations in theses parameters. Moreover, DOX significantly increase the expression levels of caspase-3 and transforming growth factor-beta 1 (TGF-β1), while IRB exhibited anti-apoptotic and anti-fibrotic effects where it abolished these elevations. Meanwhile, DOX-induced activation of p38-mitogen activated protein kinase (p38-MAPK) which was inhibited by IRB. Collectively, these results proposed that IRB afforded a significant protection against DOX-induced cardiac damage by means of antioxidant, anti-inflammatory, anti-apoptotic, and anti-fibrotic remodeling mechanisms. These mechanisms are possibly mediated, at least in part, by alterations of TGF-β1/p38-MAPK/NF-κB signaling.

AT1-receptor blockade: Protective effects of irbesartan in cardiomyocytes under hypoxic stress.

Hypoxia induces myocardial injury through the activation of inflammatory and oxidative processes. The pivotal role of the renin angiotensin system (RAS) in the pathogenesis of cardiovascular diseases has been firmly established in clinical trials and practice; in fact many experimental and clinical data have highlighted that its inhibition has a cardioprotective role. Activated RAS also stimulates inflammation directly inducing proinflammatory and oxidative gene expression. This study aimed to investigate the protective role of a pre-treatment (10 and 100 μM) with irbesartan on injury induced by 24 h of hypoxia in HL-1 cardiomyocytes; in particular, we have analyzed the natriuretic peptide (BNP) expression, a biomarker able to modulate inflammatory reaction to cardiac injury and some markers involved in oxidative stress and inflammation. Our results demonstrated that a pre-treatment with 100 μM irbesartan significantly increased SOD activity and catalase expression of 15 and 25%, respectively, compared to hypoxic cells (P<0.05). On the other hand, it was able to reduce the release of peroxynitrite and iNOS protein expression of 20 and 50% respectively (P<0.05). In addition irbesartan exerts an anti-inflammatory activity reducing Toll-like receptors (TLRs)-2 and -4 mRNA expression, TNF-alpha expression and activity (20%) and increasing the expression of the cytokine IL-17 (40%) (P<0.05 vs hypoxia). Our findings also showed that BNP induced by ischemia was significantly and in a concentration-dependent manner reduced by irbesartan. The findings of our study demonstrated that the AT1 receptor antagonist irbesartan exerts a protective role in an in vitro hypoxic condition reducing oxidative stress and inflammation.

Effects of Pioglitazone and Irbesartan on Endothelial Dysfunction on Experimentally Streptozotocin-Induced Diabetic Nephropathy in Rats

Background and Aim. Diabetes mellitus is associated with an induction of vascular endothelial dysfunction (VED) that leads to the pathogenesis of diabetic nephropathy (DN). Diabetic nephropathy (DN) is a main cause of end stage renal disease. This study was designed to investigate the protective effects of irbesartan (IRB) and its combination with pioglitazone (PIO) on impaired endothelial dysfunction, oxidative stress, and inflammation beyond blood glucose control in streptozotocin- (STZ-) induced diabetic nephropathy in rats. Materials and Methods. Forty-eight male albino rats were divided equally and randomly into six groups: A (control non- diabetic non-treated) and B (diabetic non-treated) injected intraperitoneally by streptozotocin (65mg/kg) and nicotinamide (110 mg/kg) to induce diabetic nephropathy; C (diabetic treated with IRB (30mg/kg/daily) orally), D (diabetic treated with PIO (30mg/kg/daily) orally), E (diabetic treated with IRB and PIO in doses (30 mg/kg/day and 30 mg/kg/day) orally), and F (diabetic treated with IRB and PIO in doses (5mg/kg/day and 15mg/kg/day, resp.) orally for 12 weeks). Fasting blood glucose, urea, creatinine, albumin in urine levels, IL-6, nitric oxide (NO), and Malondialdehyde peroxidase (MDA) were determined in serum of the different groups at the end of the experiment; renal blood flow and aortic and renal histopathological changes were also evaluated. Results. Administration of irbesartan and pioglitazone to diabetic rats caused significant decrease in levels of urea, creatinine, albumin, serum inflammatory mediators (IL-6 and NO), and oxidative stress markers. The effects of irbesartan and/or pioglitazone were associated with improvement of renal blood flow, and they markedly reduced vascular and renal damage induced by diabetes. Conclusion. The results of the present study support the fact that the combination between irbesartan and pioglitazone was better than monotherapy on endothelial dysfunction and diabetic nephropathy through inhibition of the pro-inflammatory mediators, NO bioavailability, and oxidative stress, which are independent of their glucose-lowering properties. And there was no significant difference between the combination of pioglitazone and irbesartan in large doses and in low doses.

Irbesartan ameliorates cardiac inflammation in type 2 diabetic db/db mice

To investigate the protective effects of irbesartan against cardiac inflammation associated with diabetes and obesity in the db/db mouse model of type 2 diabetes and explore the underlying mechanisms. Twenty- four 10-week-old diabetic db/db mice were equally randomized into irbesartan treatment (50 mg/kg per day) group and model group, using 12 nondiabetic littermates (db/+) as the controls, The mice were treated with irbesartan or saline vehicle for 16 consecutive weeks, after which the heart pathology was observed and the heart weight, body weight, and serum levels of fasting blood glucose (FBG), total cholesterol(TC), and triglycerides(TG) were measured. The expression of nuclear factor-kappaB (NF-κB) p65 in the myocardium was assessed with immunohistochemistry, the protein levels of P-IκBα ,IκBα and β-actin were analyzed with Western blotting, and the pro-inflammatory cytokines IL-6 and TNF-α mRNA were detected using quantitative real-time PCR (qPCR). Compared with db/+ mice, the saline-treated db/db mice developed obesity, hyperglycemia and hyperlipidemia (P<0.01). Histopathological examination of the heart tissue revealed inflammatory cell infiltration, increased myocardial interstitium and disorders of myocardial fiber arrangement. The diabetic mice showed increased P-IαBα and decreased IκBα protein levels, enhanced activity and expression of NF-κB in the hearts, and increased mRNA expression of IL-6 and TNF-α in the myocardium. These abnormalities were all associated with increased inflammatory response. Treatment with irbesartan improved the heart architecture and attenuated high glucose-induced inflammation in the diabetic mice. Treatment with irbesartan attenuates cardiac inflammation in type 2 diabetic db/db mice, and this effect was probably associated with the suppression of cardiac angiotensin II and NF-κB signaling pathway.

Effects of angiotensin-II receptor blockers on β-catenin expression in a rat model of experimental streptozotocin-induced early-stage of diabetic nephropathy

ObjectiveDiabetic nephropathy (DN) is one of the most common causes of end-stage renal failure. The pathogenesis of progressive renal injury is multifactorial and the mechanism by which hyperglycemia causes microangiopathy is still poorly understood. The WNT pathway is activated in DN and regulating β-catenin protein levels is referred to as the canonical Wnt/β-catenin pathway. Because the renin angiotensin system has been reported to be an important contributory factor in the pathophysiology of DN, exogenous administration of angiotensin II receptor antagonist may be beneficial in counteracting some biochemical or functional changes of DN. The aim of the study was to determine the β-catenin expression and the possible protective effects of irbesartan, an angiotensin II type 1 receptor blocker (ARB) in a rat model of streptozotocin(STZ)-induced diabetic nephropathy. MethodsSTZ-induced DN in rats was assessed biochemically by measuring urine volume, protein and creatinine clearance as well as Kidney weight/body weight (KW/BW) and the index of mesangial expansion. Three groups of male Sprague-dawley rats were used. The first group consisted of non-diabetic control rats (control). The second group was the untreated diabetic rats(STZ+vehicle). The third group consisted of diabeti rats treated with irbesartan, 50 mg/kg for 12 weeks (STZ+irbesartan). Immunohistochemical stainings and real time PCR for β-catenin were performed in renal cortex of rat modals. ResultsMarked hyperglycemia, polyuria, proteinuria, renal hypertrophy, mesangial matrix expansion and glomerular hyperfiltration were observed in STZ diabetic rats. The levels of microalbuminuria and KW/BW in the STZ+irbesartan group were lower than those in the STZ+vehicle group (P<0.05). The up-regulated immunostaining and mRNA expression of β-catenin were decreased in renal cortic of the Irbesartan-treated diabetic group, but there was no significant difference compared to the untreated diabetic group. ConclusionThe data suggest that irbesartan ameliorates proteinuria and renal hypertrophy, charactered damages of STZ-induced early-stage DN in rats, but its effective drug target is not to inhibit the up-regulated expressions of β-catenin.

Protective effect of irbesartan, an angiotensin II receptor antagonist, alone and in combination with aspirin on middle cerebral artery occlusion model of focal cerebral ischemia in rats

The present study was designed to test pretreatment multiple doses of irbesartan (IRB) 50 mg, aspirin (ASP) 100 mg and the combination of both drugs for 7 days on middle cerebral artery-occluded (MCAO) rats. Focal cerebral ischemia was induced by MCA occlusion for 2 hours followed by reperfusion for 22 hours. After 24 hours of ischemia, grip strength and locomotor activity tests were performed. Animals were immediately sacrificed, infarct volume was measured followed by the estimation of markers of oxidative stress in the whole brains. Locomotor activity and grip strength were improved in IRB- and ASP-treated rats. Infarct volume was reduced in both IRB and ASP pretreatment as compared with MCAO rats. An elevation of thiobarbituric acid reactive substance (TBARS) and a reduction in glutathione (GSH) and antioxidant enzymes viz. superoxide dismutase (SOD) and catalase were observed following MCAO. Pretreatment of IRB and ASP showed the reduction in TBARS, elevation in GSH, SOD and catalase levels as compared with MCAO rats. The protective effects of IRB, an angiotensin II receptor antagonist having affinity for AT(1) receptor subtypes, could be due to inhibition of AT( 1) receptor expression in addition to its neuroprotective and free radical scavenging properties in cerebral ischemia. Further, it may be possible that the combination of IRB and ASP may be useful as an add-on therapy and would yield beneficial effects, if administered immediately following the ischemia in reducing the severity of the neurological deficits. However, our results are preliminary, further studies with posttreatment of IRB and ASP are required to provide more firm view.

Protective effects of irbesartan and alpha lipoic acid in STZ-induced diabetic nephropathy in rats

The aim of this study was designed to investigate the possible beneficial effects of the angiotensin (ang) II T1 (AT1) receptor blocker, irbesartan (Irb), and the alpha lipoic acid (ALA) in streptozotocin (STZ)-induced diabetic nephropathy (DNP) in rats. The rats were randomly allotted into one of five experimental groups: A, control; B, diabetic untreated; C, diabetic treated with Irb; D, diabetic treated with ALA; and E, diabetic treated with Irb + ALA; each group contains 10 animals. B, C, D, and E groups received STZ. Diabetes was induced in four groups by a single intraperitoneal injection of STZ (50 mg/kg, freshly dissolved in 5 mmol/L citrate buffer, pH 4.5). The rats in Irb-, ALA-, and Irb + ALA-treated groups were given Irb (5 mg/kg), ALA (in a dose of 3 mg/kg), and Irb + ALA (in a dose of 2.5 + 1.5 mg/kg) once a day orally by using intragastric intubation for 12 weeks starting 2 days after STZ injection, respectively. Treatment with ALA and especially Irb reduced the glomerular size; thickening of capsular, glomerular, and tubular basement membranes; increased amounts of mesangial matrix and tubular dilatation as compared with diabetic-untreated rats. Notably, the better effects were obtained when Irb and ALA were given together. We conclude that Irb, ALA, and especially Irb + ALA therapy causes renal morphologic improvement after STZ-induced diabetes in rats. We believe that further preclinical research into the utility of Irb and ALA treatment, alone or its combination, may indicate its usefulness as a potential treatment in DNP.

The protective effect of irbesartan in rats fed a high fat diet is associated with modification of leptin–adiponectin imbalance

It has been shown that the renin-angiotensin system participates in the development of the metabolic syndrome. This study aimed to show whether the angiotensin II type 1 receptor blocker, irbesartan, exerts a protective effect against metabolic and cardiovascular abnormalities in rats fed a high fat diet (HFD). Wistar rats (n = 30) were divided into three groups: (1) rats fed a standard diet for 7 weeks were used as a control group; (2) rats fed a HFD (33.5% fat) for 7 weeks; and (3) rats fed a HFD (33.5% fat) treated with irbesartan (0.1 mg/kg per day) for 7 weeks. Body weight, white and brown adipose tissue weight, plasma concentrations and protein expression of leptin and adiponectin in white adipose tissue, and glucose metabolism were investigated. Vascular reactivity in aortic rings and heart function were also evaluated. HFD rats showed increased (P < 0.05) body, epididymal and lumbar adipose tissue weights, but did not experience a change in brown adipose tissue weight. Irbesartan attenuated (P < 0.05) all of these parameters, but increased brown adipose tissue weight. The leptin/adiponectin ratio of plasma concentrations and protein expression in lumbar adipose tissue increased (P < 0.05) in HFD rats, and were normalized by irbesartan. Along with these changes, irbesartan improved (P < 0.05) insulin sensitivity and exaggerated responses to angiotensin I and II in the aorta. Irbesartan reduced body and white adipose tissue weights, improved glucose metabolism and vascular function in the aorta. The correction of leptin-adiponectin imbalance may be an important mechanism participating in the protective effect of irbesartan in HFD rats.

Irbesartan attenuates contrast media-induced NRK-52E cells apoptosis

Background Radiocontrast nephropathy (RCN) is a major complication after radiographic examination. The precise mechanisms underlying RCN are not well understood. Renal tubular cell apoptosis is a feature of RCN, but hyperosmolality cannot fully explain the cytotoxicity of contrast media. There is accumulating evidence that reactive oxygen species (ROS) is involved in the pathophysiology of RCN, whereas the correlation between oxidative stress and contrast media-induced cell apoptosis is not clear. We hypothesized that ROS mediated apoptosis in renal tubular cells exposed to contrast media. Irbesartan, a selective AT 1 receptor antagonist has been demonstrated an antioxidative effect. The present study was designed to determine whether irbesartan attenuated the contrast media-induced renal tubular cell apoptosis. Methods NRK-52E cells were exposed to increasing concentration (25, 50, 100, 150 mg iodine mL −1, 335, 384, 420, 521 mOsm kg −1) of ioversol (a non-ionic contrast media) for 1 h or incubated in ioversol (100 mg iodine mL −1, 420 mOsm kg −1) for 15 min, 30 min, 60 min, 120 min, 240 min, respectively. Mannitol with the same osmolality as ioversol (420 mOsm kg −1) also treated NRK-52E cells for 1 h. In separate experiment, irbesartan (0.01, 0.1, 1 mmol L −1) was added 1 h before incubation with ioversol (100 mg iodine mL −1, 420 mOsm kg −1) for 1 h. Apoptosis was determined by Hoechst staining and flow cytometry with annexinV-FITC and propidium iodide. The intracellular formation of ROS was detected by confocal microscopy with fluorescent probe CM-H 2DCFDA. Bax and bcl-2 mRNA expression were determined by reverse transcription–polymerase chain reaction (RT–PCR). Results Ioversol induced NRK-52E cells apoptosis in a concentration- and time-dependent manner. The intracellular ROS generation was greatly increased following ioversol stimulus. Furthermore, ioversol induced a decrease in the expression for bcl-2 mRNA and an increase for bax mRNA. Irbesartan attenuated the ioversol-induced apoptosis in NRK-52E cells in a dose-dependent manner, in which the protective effect of irbesartan was dependent on decreasing intracellular ROS formation. In addition, irbesartan reversed the ioversol-induced increase in bax mRNA and decrease in bcl-2 mRNA. Conclusion Ioversol induced NRK-52E cells apoptosis in a concentration- and time-dependant manner via an increase in oxidative stress and subsequent to the increase in mRNA expression for bax and reduction in bcl-2 mRNA. Irbesartan attenuated the ioversol-induced apoptosis in NRK-52E cells by reducing oxidative stress and reversing the enhancement of bax mRNA and the reduction in bcl-2 mRNA.