Age-dependent effect of high-fructose and high-fat diets on lipid metabolism and lipid accumulation in liver and kidney of rats.

Background: The metabolic syndrome (MS) is characterized by variable coexistence of metabolic and pathophysiological alterations which are important risk factors for developing of type II diabetes and/or cardiovascular diseases. Increased of MS patients in worldwide has stimulated the development of experimental models. However, it is still challenging to find an dietetic model that most closely approximates human MS and, in addition, is not yet fully established the effect of different diets of MS in lipid metabolism in rats of different ages. The aim of this study was to evaluate the effect of different diets of MS in lipid metabolism and ectopic fat deposition and define the most appropriate diet for inducing the characteristic disturbances of the human MS in rats of different ages. Methods: Young (4 weeks old) and adult rats (12 weeks old) were given a high-fat (FAT) or high-fructose diet (FRU) for 13 weeks and biochemical, physiological, histological and biometric parameters were evaluated. Results: In young rats, the FAT diet induced increased mean blood pressure (MAP) and heart rate (HR), body weight after 6 to 10 weeks, and in the 13th week, increased the liver, mesenteric, retroperitoneal and epididymal fat weights,fasting glucose, alanine aminotransferase (ALT) and aspartate aminotransferase (AST) and reduced HDL cholesterol; and also induced non-alcoholic fatty liver disease (NAFLD) and renal inflammatory infiltrates. In adult rats, the FRU diet induced transient elevations of MAP and HR in the 6th week, and, at 13 weeks, increased fasting glucose, triglycerides, total cholesterol, AST and ALT; increased liver, kidneys and retroperitoneal fat weights; and induced macrovesicular and microvesicular NAFLD, the presence of fat cells in the kidney, glomerular sclerosis, and liver and kidney inflammation. Additionally, the FAT and FRU diets induced, respectively, increases in liver glycogen in adults and young rats. Conclusions: Our data show that FRU diet in adult rats causes biggest change on metabolism of serum lipids and lipid accumulation in liver and kidney, while the FAT diet in young rats induces elevation of MAP and HR and higher increased visceral lipid stores, constituting the best nutritional interventions to induce MS in rats

Oral Ang-(1-7) treatment improves white adipose tissue remodeling and hypertension in rats with metabolic syndrome.

Objective: Angiotensin (Ang)-(1-7) has preventive effects on metabolic syndrome (MetS). The aim of this study was to evaluate the therapeutic effect of oral Ang-(1-7) on mean arterial pressure (MAP), insulin resistance (IR), inflammatory process, and remodeling of white adipose tissue (WAT) in rats with establishedMetS. Methods: Rats were subjected to control (CT; AIN-93M) or high-fat (HF) diets for 13 wk to induce MetS and treated with Ang-(1-7) or vehicle (V) for the last 6 wk. At the end of 13 wk, MAP, biochemical and histological parameters, and uncoupling protein (UCP) and inflammatory gene expression were determined by quantitative reverse transcription polymerase chain reaction. Results: HF-V rats showed increased visceral fat deposition, inflammatory cytokine expression, hyperplasia, and hypertrophy in retroperitoneal (WAT) and brown adipose tissue (BAT). Additionally, the gastrocnemius muscle reduced UCP-3 and increased the UCP-1 expression in BAT. HF-V also elevated levels of plasma insulin, glucose, homeostatic model assessment (HOMA) of IR and HOMA-b, and increased body mass, adiposity, and MAP. Ang-(1-7) treatment in rats with MetS [HF-Ang-(1-7)] reduced WAT area, number of adipocytes, and expression of proinflammatory adipokines in WAT and BAT and increased UCP-3 in gastrocnemius muscle and UCP-1 expression in BAT compared with the HF-V group. These events prevented body mass gain, reduced adiposity, and normalized fasting plasma glucose, insulin levels, HOMA-IR, HOMA-b, and MAP. Conclusion: Data from the present study demonstrated that oral Ang-(1-7) treatment is effective in restoring biochemical parameters and hypertension in established MetS by improving hypertrophy and hyperplasia in WAT and inflammation in adipose tissue, and regulating metabolic processes in the gastrocnemius muscle and BAT

Antioxidant effects of oral Ang-(1-7) restore insulin pathway and RAS components ameliorating cardiometabolic disturbances in rats.

In prevention studies of metabolic syndrome (MetS), Ang-(1-7) has shown to improve the insulin signaling. We evaluated the HP?CD/Ang-(1-7) treatment on lipid metabolism, renin-angiotensin system (RAS) components, oxidative stress, and insulin pathway in the liver and gastrocnemius muscle and hepatic steatosis in rats with established MetS. After 7 weeks of high-fat (FAT) or control (CT) diets, rats were treated with cyclodextrin (HP?CD) or HP?CD/Ang-(1-7) in the last 6 weeks. FATHP?CD/ empty rats showed increased adiposity index and body mass, gene expression of ACE/ANG II/AT1R axis, and oxidative stress. These results were accompanied by imbalances in the insulin pathway, worsening of liver function, hyperglycemia, and dyslipidemia. Oral HP?CD/Ang-(1-7) treatment decreased ACE and AT1R, increased ACE2 gene expression. in the liver, and restored thiobarbituric acid reactive substances (TBARS), catalase (CAT), superoxide dismutase (SOD), insulin receptor substrate (Irs-1), glucose transporter type 4 (GLUT4), and serine/threonine kinase 2 (AKT-2) gene expression in the liver and gastrocnemius muscle improving hepatic function, cholesterol levels, and hyperglycemia in MetS rats. Overall, HP?CD/Ang-(1-7) treatment restored the RAS components, oxidative stress, and insulin signaling in the liver and gastrocnemius muscle contributing to the establishment of blood glucose and lipid homeostasis in MetS rats

Efeito do óxido nítrico na regulação de parâmetros cardiovasculares pela CVLM em ratos com hipertensão renovascular 2R1C”.

A hipertensão arterial pode ocorrer devido à hiperatividade de neurônios do bulbo ventrolateral rostral (RVLM) (Chan e cols., 1991; Boone e McMillen, 1994; Suzuki e cols., 1994; Minson e cols., 1996) e/ou devido a um tônus reduzido dos neurônios GABAérgicos do bulbo ventrolateral caudal (CVLM) que se projetam para a RVLM. (Smith e Barron, 1990b; a; Colombari e cols., 2001). Além disso, foi observado que durante a hipertensão ocorre uma elevação dos níveis de óxido nítrico (NO) na CVLM. No entanto, não existem estudos conclusivos acerca do papel do NO na CVLM durante o desenvolvimento e/ou manutenção desta patologia. Diante dessas considerações, o objetivo do presente estudo foi avaliar o efeito do NO na CVLM sobre a pressão arterial média (PAM), freqüência cardíaca (FC) e sensibilidade da bradicardia reflexa em animais com hipertensão renovascular 2R1C. Ratos fisher (150 a 200g) foram anestesiados com uma mistura de quetamina (50 mg/Kg, i.p.) e xilasina (5 mg/Kg, i.p.) para realização da cirurgia para indução da hipertensão renovascular (2R1C) ou fictícia (SHAM). Após 30 dias, os animais foram anestesiados com uretana (1,2g/kg, i.p), posicionados em um aparelho estereotáxico para exposição do bulbo e instrumentados para registro da PAM e FC. A sensibilidade da bradicardia reflexa foi avaliada através da injeção de doses crescentes de fenilefrina (i.v.). Ao final dos experimentos os animais foram sacrificados, os rins e coração pesados e o cérebro submetido à análise histológica. Os animais 2R1C apresentam menor peso relativo do rim esquerdo (clipado) (0,28 ± 0,02g, n=11), maior peso relativo do rim contralateral (0,52 ± 0,05g, n=11), maior peso relativo do coração (0,41 ± 0,02g, n=11) e ventrículo esquerdo (0,31± 0,02, n=11) e aumento da PAM (142 ± 3 mmHg, n=36) em comparação aos ratos SHAM (0,34 ± 0,01g; 0,35 ± 0,01g; 0,30 ± 0,01g; 0,20 ± 0,01g, n=11 e 106 ± 2 mmHg, n=42 respectivamente) A microinjeção de nitro-L-arginina-metil-ester, L-NAME (inibidor não seletivo do NO, 10nmol) na CVLM, produziu uma queda na PAM e na FC em animais 2R1C (-17 ± 3 mmHg e -29 ± 8 bpm, n=7, respectivamente) e em animais SHAM (-17 ± 3 mmHg e -39 ± 15 bpm, n=6, respectivamente). Já a microinjeção de L-ARGININA (precursor do NO, 50nmol) na CVLM produziu uma elevação na PAM de ratos 2R1C (11 ± 3 mmHg, n=6) e SHAM (11 ± 1 mmHg, n=11), além de alterações variadas sobre a FC em ambos os grupos (-12 ± 6 bpm, n=6, grupo SHAM; 8 ± 8 bpm, n=11, grupo 2R1C). IX Em animais 2R1C, observamos que o tempo de duração da bradicardia produzida pela microinjeção de L-NAME na CVLM foi inferior (11 ± 1 min, n=11) ao tempo de duração em animais SHAM (23 ± 3 min, n=6). Adicionalmente, a duração do efeito hipertensor da microinjeção de L-ARGININA em animais 2R1C (26 ± 7 min, n=4) e das alterações variadas produzidas pela mesma sobre a FC (32 ± 5 min, n=6) foram superiores, quando comparado aos ratos SHAM (10 ± 2 min e 14 ± 4 min, n=7-10, respectivamente). Os efeitos cardiovasculares produzidos pela microinjeção da LARGININA na CVLM foram abolidos pela microinjeção prévia de L-NAME na CVLM de ratos SHAM e 2R1C. A bradicardia reflexa dos animais 2R1C foi menor (0,11 ± 0,02 ms/mmHg, n=17) quando comparada aos ratos SHAM (0,42 ± 0,08 ms/mmHg, n=14). A microinjeção do LNAME na CVLM produziu um aumento da sensibilidade da bradicardia reflexa em animais 2R1C (0,18 ± 0,04 ms/mmHg, n=8) em comparação com a sensibilidade da bradicardia reflexa antes da microinjeção do L-NAME (0,07 ± 0,01 ms/mmHg, n=10). Já a microinjeção de L-ARGININA na CVLM produziu uma redução da sensibilidade da bradicardia reflexa nos ratos SHAM (0,29 ± 0,03 ms/mmHg, n=6) em relação à sensibilidade da bradicardia reflexa antes da microinjeção de L- ARGININA (de 0,52 ± 0,08 ms/mmHg, n=6). Os resultados do presente estudo reforçam a idéia de que o NO esteja aumentado na CVLM durante a hipertensão arterial. Esses níveis elevados de NO parecem ter um papel inibitório sobre os neurônios da CVLM, contribuindo para o desenvolvimento e/ou manutenção da hipertensão renovascular e para a baixa sensibilidade do barorreflexo que ocorre nesta patologia.Hypertension may occur due to hyperactivity of neurons in the rostral ventrolateral medulla (RVLM) (Chan et al. 1991; Boone and McMillen, 1994, Suzuki et al. 1994; Minson et al., 1996) and/or due to a reduced tone of GABAergic neurons of the caudal ventrolateral medulla (CVLM) that projects to the RVLM. Furthermore, during hypertension occurs an elevation of nitric oxide (NO) in the CVLM. However, there are no conclusive studies about the role of NO in the CVLM during development and/or maintenance of this pathology. Thus, the objective of this study was to evaluate the effect of NO in the CVLM on the mean arterial pressure (MAP), heart rate (HR) and reflex bradycardia in renovascular hypertensive rats (2K1C). Male Fisher rats (150 to 200g) were anesthetized with a mixture of ketamine (50 mg / kg, ip) and xylazine (5 mg / kg, ip) for the 2K1C or SHAM surgeries. 30 days after these surgeries, the 2K1C and SHAM animals were anesthetized with urethane (1.2 g / kg, ip), positioned in a stereotactic apparatus to expose the medulla and instrumented for MAP and HR measurements. Baroreflex control of HR was determined by recording reflex heart rate changes in response to transient increases in MAP produced by repeated bolus injections of graded doses of phenylephrine (0.25 to 5 mg, iv) before and after microinjections of L-NAME (10nmol) or L-ARGININE (50nmol). After carrying out the experiments the animals were sacrificed. The kidneys and heart were weighed and the brain submitted to histological analysis. The 2K1C animals showed lower relative weight of the left kidney (clipped) (0.28 ± 0.02 g, n=11), increased relative weight of the contralateral kidney (0.52 ± 0.05 g, n=11), greater relative heart weight (0.41 ± 0.02 g, n=11) and left ventricle (0.31 ± 0.02, n=11) and an increase in MAP (142 ± 3 mmHg, n = 36) compared to the SHAM rats (0.34 ± 0.01 g, 0.35 ± 0.01 g, 0.30 ± 0.01 g, 0.20 ± 0.01 g, n = 11 and 106 ± 2 mmHg, n=42 respectively) The microinjection of L-NAME in the CVLM produced a fall in MAP and HR of both animals 2K1C (-17 ± 3 mmHg and -29 ± 8 beats/min, n=7, respectively) and SHAM animals (-17 ± 3 mmHg and -39 ± 15 beats/min, n=6, respectively). The microinjection of L- ARGININE in the CVLM produced an increase in MAP and variable changes in the HR in 2K1C (11 ± 3 mmHg and -12± 6 beats/min, n = 6, respectively) and in the SHAM rats (11 ± 1 mmHg and 8 ± 8 beats/min, n=11, respectively). In 2K1C rats, we observed that the duration of the bradycardia produced by XI microinjection of L-NAME in the CVLM was lower (11 ± 1 min, n=11) than in SHAM animals (23 ± 3 min, n=6). In addition, the duration of the hypertensive effect of microinjection of L- ARGININE in 2K1C rats (26 ± 7 min, n=4) and the variable changes produced by microinjection of L- ARGININE on the HR (32 ± 5 min, n=6) were higher when compared to SHAM rats (10 ± 2 min and 14 ± 4 min, n=7-10, respectively). Cardiovascular effects produced by microinjection of L- ARGININE in the CVLM were abolished by prior microinjection of L-NAME in the CVLM of SHAM and 2K1C rats. The reflex bradycardia sensitivity in 2K1C animals was lower (0.11 ± 0.02 ms / mmHg, n=17) compared to SHAM rats (0.42 ± 0.08 ms / mmHg, n=14). The microinjection of L-NAME in the CVLM produced an increase in the reflex bradycardia sensitivity of 2K1C animals (0.18 ± 0.04 ms / mmHg compared to 0.07 ± 0.01 ms / mmHg, n=10; before LNAME). In addition, the microinjection of L- ARGININE in the CVLM produced a reduction of reflex bradycardia only in SHAM rats (0.29 ± 0.03 ms / mmHg compared to 0.52 ± 0.08 ms / mmHg, n = 6; before L-arginine). The results of this study reinforce the idea that NO participates in the development of hypertension, possibly by increasing its levels in the CVLM. Moreover, these high levels of NO appear to have an inhibitory role on the CVLM neurons, contributing to the low sensitivity of the baroreflex that occurs in the renovascular hypertension

Tratamento com hpβcd/ang-(1-7) reverte distúrbios da síndrome metabólica através da redução do processo inflamatório do tecido adiposo, da melhora da via da insulina e do aumento da termogênese adaptativa.

Programa de Pós-Graduação em Ciências Biológicas. Núcleo de Pesquisas em Ciências Biológicas, Pró-Reitoria de Pesquisa de Pós Graduação, Universidade Federal de Ouro Preto.O objetivo do presente estudo foi avaliar o potencial terapêutico da formulação oral de Ang-(1-7), a HPβCD/Ang-(1-7), sobre o processo inflamatório do tecido adiposo branco visceral (TAV) e tecido adiposo marrom (TAM), sobre as vias de sinalização intracelular da insulina e sobre a termogênese adaptativa, na reversão de distúrbios metabólicos da síndrome metabólica (SM), induzidos pela dieta hiperlipídica. Ratos recém-desmamados com 4 semanas de idade, foram submetidas à dieta controle AIN-93 (dieta CT) ou à dieta hiperlipídica (dieta SM) por 7 semanas para indução da SM. Após este período, os grupos foram subdivididos em ratos tratados com HPβCD/Ang-(1-7) ou com ciclodextrina vazia (V) por mais 6 semanas. Ao final das 13 semanas de experimento foram realizadas avaliações biométricas, bioquímicas, Elisa e expressões gênicas por qRT-PCR. Os ratos SM-V apresentaram aumento da expressão de citocinas inflamatórias no TAV retroperitoneal e no TAM, redução da expressão do PPARγ2 no fígado, piora da via intracelular da insulina no fígado, no TAV retroperitoneal e no músculo gastrocnêmico, redução na expressão de PGC1-α, PGC1-β, UCP-2 e UCP-3 no gastrocnêmico e aumento da expressão de UCP-1 no TAM. Esses eventos ocorreram simultaneamente com a elevação da glicemia de jejum, da insulina, do HOMA-IR e do HOMA-ß e com o aumento do peso corporal, do índice de adiposidade, do colesterol total, do LDL e da alanina transferase (ALT). O tratamento com HPβCD/Ang-(1-7) reduziu a expressão das adipocinas pró-inflamatórias do TAV e TAM, normalizou a expressão de PPARγ2 no fígado, melhorou a via intracelular da insulina no fígado, no TAB retroperitoneal e no músculo gastrocnêmico e aumentou a expressão de UCP-3 no músculo gastrocnêmico e a expressão de UCP-1 no TAM, quando comparado ao grupo controle CT-V. Esses eventos impediram o aumento do peso corporal, reduziram o índice de adiposidade e os níveis de colesterol total, além de normalizar a glicemia de jejum, os níveis de insulina, o HOMA-IR, o HOMA-ß, e os níveis de ALT. Nossos dados demonstram a eficácia do tratamento com HPβCD-Ang-(1-7) ao mostrar que essa formulação reverte distúrbios metabólicos da SM em ratos, a partir de alterações benéficas teciduais.The aim of this study was to evaluate the therapeutic potential of the oral formulation of Ang-(1-7), the HPβCD/Ang-(1-7), on the inflammatory process of visceral white adipose tissue (WAT) and brown adipose tissue (BAT) and on intracellular signaling pathways of insulin and on the adaptive thermogenesis, in reversion of metabolic syndrome (MS) and related disorders induced by high-fat diet. Rats weaned at 4 weeks of age, were subjected to AIN-93 diet control (CT diet) or high fat diet (SM diet ) for 7 weeks for the induction of MS. After this period, the rats were divided into groups treated with HPβCD/Ang- (1-7) or empty cyclodextrin (V) for further six weeks. At the end of the experiment biometric, biochemical, Elisa and qRT-PCR assays were performed. SM-V rats showed increase in inflammatory cytokines expression in the retroperitoneal WAT and BAT, reduction in PPARγ2 expression in the liver, worsening in insulin signaling pathways in the liver, retroperitoneal WAT and gastrocnemius, reduction in PGC1- α, PGC1-β, UCP-2 and UCP-3 expression in gastrocnemius and an increase in UCP-1 expression in the TAM. These events occur simultaneously with the elevation of fasting glucose, insulin, HOMA-IR and HOMA-ß and with increasing the body weight, adiposity index, total cholesterol, LDL and alanine aminotransferase (ALT). Treatment with HPβCD/Ang-(1-7) reduced the inflammatory adipokines expression in retroperitoneal WAT and BAT, normalized PPARγ2 expression in the liver, improved the insulin signaling pathway in the liver, retroperitoneal WAT and gastrocnemius, increased UCP-3 expression in gastrocnemius and increased UCP-1 expression in TAM compared to CT-V group. These events prevented the increase in body weight, reduced adiposity index and total cholesterol, and normalized fasting plasma glucose, insulin, HOMA-IR, HOMA-ß, and ALT. Our data demonstrate the efficacy of HPβCD/Ang-(1-7) treatment and show that this formulation reverses MS and related disorders through of tissue beneficial changes

Physical training improves thermogenesis and insulin pathway, and induces remodeling in white and brown adipose tissues.

Physical training (PT) has been considered as a treatment in metabolic syndrome (MS), since it induces thermogenic activity in brown (BAT) and white (WAT) adipose tissues. We evaluated the therapeutic effect of PT on activity of WAT and BAT in rats with MS induced by high-fat diet (30% lard) for 13 weeks and submitted, for the last 6 weeks, to swimming or kept sedentary (SED) rats. MS-SED rats compared to control diet (CT-SED) rats showed low physical fitness and high levels of glucose, insulin, homeostasis evaluation of insulin resistance (HOMA-IR), homeostasis evaluation of the functional capacity of ?-cells (HOMA-?), and blood pressure. The gastrocnemius muscle decreased in peroxisome proliferator-activated receptor gamma coactivator 1-alpha and beta (PGC-1?, PGC-1?), and uncoupled protein 2 and 3 (UCP2 and UCP3) expressions. Both WAT and BAT increased in the adipocyte area and decreased in blood vessels and fibroblast numbers. WAT increased in expression of pro-inflammatory adipokines and decreased in anti-inflammatory adipokine and adiponectin. WAT and gastrocnemius showed impairment in the insulin signaling pathway. In response to PT, MS rats showed increased physical fitness and restoration of certain biometric and biochemical parameters and blood pressure. PT also induced thermogenic modulations in skeletal muscle, WAT and BAT, and also improved the insulin signaling pathway. Collectively, PT was effective in treating MS by inducing improvement in physical fitness and interchangeable effects between skeletal muscle, WAT and BAT, suggesting a development of brown-like adipocyte cells

Angiotensin-(1-7) antagonist, A-779, microinjection into the caudal ventrolateral medulla of renovascular hypertensive rats restores baroreflex bradycardia.

In the present study we evaluated the effect of caudal ventrolateral medulla (CVLM) microinjection of the main angiotensin (Ang) peptides, Ang II and Ang-(1-7), and their selective antagonists on baseline arterial pressure (AP) and on baroreceptor-mediated bradycardia in renovascular hypertensive rats (2K1C). Microinjection of Ang II and Ang-(1-7) into the CVLM of 2K1C rats produced similar decrease in AP as observed in Sham rats. In both Sham and 2K1C, the hypotensive effect of Ang II and Ang-(1-7) at the CVLM was blocked, for up to 30 min, by previous CVLM microinjection of the Ang II AT 1 receptor antagonist, Losartan, and Ang-(1-7) Mas antagonist, A-779, respectively. As expected, the baroreflex bradycardia was lower in 2K1C in comparison to Sham rats. CVLM microinjection of A-779 improved the sensitivity of baroreflex bradycardia in 2K1C hypertensive rats. In contrast, Losartan had no effect on the baroreflex bradycardia in either 2K1C or Sham rats. These results suggest that Ang-(1-7) at the CVLM may contribute to the low sensitivity of the baroreflex control of heart rate in renovascular hypertensive rat

Angiotensin-(1-7) antagonist, A-779, microinjection into the caudal ventrolateral medulla of renovascular hypertensive rats restores baroreflex bradycardia.

In the present study we evaluated the effect of caudal ventrolateral medulla (CVLM) microinjection of the main angiotensin (Ang) peptides, Ang II and Ang-(1-7), and their selective antagonists on baseline arterial pressure (AP) and on baroreceptor-mediated bradycardia in renovascular hypertensive rats (2K1C). Microinjection of Ang II and Ang-(1-7) into the CVLM of 2K1C rats produced similar decrease in AP as observed in Sham rats. In both Sham and 2K1C, the hypotensive effect of Ang II and Ang-(1-7) at the CVLM was blocked, for up to 30 min, by previous CVLM microinjection of the Ang II AT 1 receptor antagonist, Losartan, and Ang-(1-7) Mas antagonist, A-779, respectively. As expected, the baroreflex bradycardia was lower in 2K1C in comparison to Sham rats. CVLM microinjection of A-779 improved the sensitivity of baroreflex bradycardia in 2K1C hypertensive rats. In contrast, Losartan had no effect on the baroreflex bradycardia in either 2K1C or Sham rats. These results suggest that Ang-(1-7) at the CVLM may contribute to the low sensitivity of the baroreflex control of heart rate in renovascular hypertensive rat