Selective Angiotensin II Receptor Antagonism Reduces Insulin Resistance in Obese Zucker Rats
Bristol-Myers Squibb, New York, New York, United States Hypertension
(Impact Factor: 6.48).
10/2001; 38(4):884-90. DOI: 10.1161/hy1101.092970
Effects of oral administration of the angiotensin II receptor antagonist (selective AT(1)-subtype) irbesartan on glucose tolerance and insulin action on skeletal-muscle glucose transport were assessed in the insulin-resistant obese Zucker rat. In the acute study, obese rats received either vehicle (water) or irbesartan 1 hour before the experiment. Although irbesartan had no effect on glucose transport (2-deoxyglucose uptake) in the epitrochlearis muscle, which consists mainly of type IIb fibers, acute angiotensin II receptor antagonism led to a dose-dependent increase in insulin action in the predominantly type I soleus muscle. Irbesartan at 25 and 50 mg/kg induced significant increases (41% and 50%, respectively; P<0.05) in insulin-mediated glucose transport. Moreover, these acute irbesartan-induced improvements in soleus-muscle glucose transport were associated with enhancements in whole-body insulin sensitivity (r=-0.732; P<0.05), as assessed during an oral glucose tolerance test. After chronic administration of irbesartan (21 days at 50 mg. kg(-1). d(-1)), glucose tolerance was enhanced further, and insulin-mediated glucose transport was significantly elevated in both epitrochlearis (32%) and soleus (73%) muscle. Chronic angiotensin II receptor antagonism was associated with significant increases in glucose transporter-4 (GLUT-4) protein expression in soleus (22%) and plantaris (20%) muscle and myocardium (15%). Chronic irbesartan-induced increases in whole-body insulin sensitivity were associated with increased insulin-mediated glucose transport in both epitrochlearis (r=-0.677; P<0.05) and soleus (r=-0.892; P<0.05) muscle. In summary, angiotensin II receptor (AT(1)-subtype) antagonism, either acutely or chronically, improves glucose tolerance, at least in part because of an enhancement in skeletal-muscle glucose transport, and the effect of chronic angiotensin II receptor antagonism on type I skeletal-muscle glucose uptake is associated with an increase in GLUT-4 protein expression.
Available from: Sérgio Henrique Sousa Santos
- "In addition, other ACEi (temocapril) were demonstrated to improve insulin resistance and glucose intolerance through increasing glucose uptake, especially in skeletal muscle, at least in part through enhancement of the bradykinin-nitric oxide (NO) system and consequently glucose transporter-4 (GLUT-4) translocation . Moreover, oral administration of irbesartan, either acutely or chronically, improves glucose tolerance, at least in part because of an enhancement in skeletal-muscle glucose transport, and the effect of chronic angiotensin II receptor antagonism on type I skeletal-muscle glucose uptake is associated with an increase in GLUT-4 protein expression . "
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ABSTRACT: Angiotensin-(1-7) is one of the most important active peptides of the Renin-Angiotensin System (RAS) with recognized cardiovascular relevance; however recently several studies have shown the potential therapeutic role of Ang-(1-7) on treating and preventing metabolic disorders as well. This peptide achieves a special importance considering that in the last few decades obesity and metabolic syndrome (MS) have become a growing worldwide health problem. Angiotensin (Ang) II is the most studied component of RAS and is increased during obesity, diabetes and dyslipidemia (MS); some experimental evidence has shown that Ang II modulates appetite and metabolism as well as mechanisms that induce adipose tissue growth and metabolism in peripheral organs. Recent articles demonstrated that Ang-(1-7)/Mas axis modulates lipid and glucose metabolism and counterregulates the effects of Ang II. Based on these data, angiotensin-converting enzyme 2 (ACE2)/Ang-(1-7)/Mas pathway activation have been advocated as a new tool for treating metabolic diseases. This review summarizes the new evidence from animal and human experiments indicating the use of Ang-(1-7) in prevention and treatment of obesity and metabolic disorders.
Available from: Leonardo Del Valle Mondragón
- "resistance, hypertriglyceridemia, fatty liver, obesity, and myogenic and adipogenic differentiation in muscle tissue in rats receiving a high fructose diet rats  . Moreover, chronic treatment either with ACE or AT1 inhibitors improves insulin sensitivity, decreases obesity and reduces the incidence of diabetes  . Captopril, an ACE inhibitor, decreased body weight gain partly through Ang1-7/Mas receptor/PI3K pathway . "
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ABSTRACT: Renin Angiotensin System (RAS) plays an important role in the development of Metabolic Syndrome (MS) and in aging. Angiotensin 1-7 (Ang 1-7) has opposite effects to Ang II. All of the components of RAS are expressed locally in adipose tissue and there is over-activation of adipose RAS in obesity and hypertension. We determined serum and abdominal adipose tissue Ang II and Ang 1-7 in control and MS rats during aging and the expression of AT1, AT2 and Mas in white adipose tissue. MS was induced by sucrose ingestion during 6, 12 and 18 months. During aging, an increase in body weight, abdominal fat and dyslipidemia were found but increases in aging MS rats were higher. Control and MS concentrations of serum Ang II from 6 month old rats were similar. Aging did not modify Ang II seric concentration in control rats but decreased it in MS rats. Ang II levels increased in WAT from both groups of rats. Serum and adipose tissue Ang 1-7 increased during aging in MS rats. Western blot analysis revealed that AT1 expression increased in the control group during aging while AT2 and Mas remained unchanged. In MS rats, AT1 and AT2 expression decreased significantly in aged rats. The high concentration of Ang 1-7 and adiponectin in old MS rats might be associated to an increased expression of PPAR-γ. PPAR-γ was increased in adipose tissue from MS rats. It decreased with aging in control rats and showed no changes during aging in MS rats. Ang 1-7/Mas axis was the predominant pathway in WAT from old MS animals and could represent a potential target for therapeutical strategies in the treatment of MS during aging.
Available from: Lance A Stechschulte
- "RAS is recognized as contributing to the development of osteoporosis independently of hypertension –, and a blockage of this system either at the level of angiotensin enzyme inhibitor (ACEI) or at the level of angiotensin receptors proved to be beneficial for bone , . Beside its anti-hypertensive activity, TEL has a unique ability to bind and activate PPARγ ,  and has a beneficial effects on insulin sensitivity in humans – and rodents . As compared to full agonists, pioglitazone and ROSI, TEL binds PPARγ in a different fashion which results in a distinct pattern of cofactors recruitment and different pharmacological effects . "
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ABSTRACT: Peroxisome proliferator activated receptor gamma (PPARγ) controls both glucose metabolism and an allocation of marrow mesenchymal stem cells (MSCs) toward osteoblast and adipocyte lineages. Its activity is determined by interaction with a ligand which directs posttranscriptional modifications of PPARγ protein including dephosphorylation of Ser112 and Ser273, which results in acquiring of pro-adipocytic and insulin-sensitizing activities, respectively. PPARγ full agonist TZD rosiglitazone (ROSI) decreases phosphorylation of both Ser112 and Ser273 and its prolonged use causes bone loss in part due to diversion of MSCs differentiation from osteoblastic toward adipocytic lineage. Telmisartan (TEL), an anti-hypertensive drug from the class of angiotensin receptor blockers, also acts as a partial PPARγ agonist with insulin-sensitizing and a weak pro-adipocytic activity. TEL decreased S273pPPARγ and did not affect S112pPPARγ levels in a model of marrow MSC differentiation, U-33/γ2 cells. In contrast to ROSI, TEL did not affect osteoblast phenotype and actively blocked ROSI-induced anti-osteoblastic activity and dephosphorylation of S112pPPARγ. The effect of TEL on bone was tested side-by-side with ROSI. In contrast to ROSI, TEL administration did not affect bone mass and bone biomechanical properties measured by micro-indentation method and did not induce fat accumulation in bone, and it partially protected from ROSI-induced bone loss. In addition, TEL induced "browning" of epididymal white adipose tissue marked by increased expression of UCP1, FoxC2, Wnt10b and IGFBP2 and increased overall energy expenditure. These studies point to the complexity of mechanisms by which PPARγ acquires anti-osteoblastic and pro-adipocytic activities and suggest an importance of Ser112 phosphorylation status as being a part of the mechanism regulating this process. These studies showed that TEL acts as a full PPARγ agonist for insulin-sensitizing activity and as a partial agonist/partial antagonist for pro-adipocytic and anti-osteoblastic activities. They also suggest a relationship between PPARγ fat "browning" activity and a lack of anti-osteoblastic activity.
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