Moderate exercise training does not prevent the reduction in myocardial L-type Ca2+ channels protein expression at obese rats

HIBISCUS INCREASES FUNCTIONAL CAPACITY AND THE ANTI-OBESITY EFFECT IN TRAINED OBESE RATS

ABSTRACT Introduction Hibiscus sabdariffa (Hs) has been widely used for weight loss and in the fight against obesity-associated comorbidities. Objective To evaluate the effects of Hs and physical training on the functional capacity of normal-weight and obese rats. Methods Wistar rats were distributed into eight experimental groups: control (C, n = 8) , Hibiscus Sabdariffa (Hs, n = 8), high-intensity interval training (IT, n = 8), high-intensity interval training + Hibiscus Sabdariffa (ITHs, n = 8), obese (O, n = 8), obese + continuous aerobic training (OAT, n = 8), obese + Hibiscus Sabdariffa (OHs, n = 8), , and obese + continuous aerobic training + Hibiscus Sabdariffa (OATHs, n = 8). Hibiscus Sabdariffa extract was administered for 60 days in a dose of 150 mg/kg of body weight. The maximum progressive effort test (MPET) was performed on a treadmill at the beginning and end of the study. The variables analyzed were maximum speed Vmáx time, and distance covered. Lactate was measured immediately after the MPET. Functional capacity was evaluated by the distance/adiposity index. The ANOVA with Bonferroni post hoc and Pearson’s correlation tests were used at a 5% significance level. Results After both types of training, moderate-intensity continuous and high-intensity interval performed on the treadmill, final body weight, weight gain, and the adiposity index decreased, and Vmax, time, and distance covered in the MPET increased, in addition to an improvement in functional capacity. Hs supplementation reduced the adiposity index in normal-weight and obese rats. Hs associated with aerobic training reduced final body weight and increased functional capacity. Conclusion Hs supplementation promoted a reduction in the adiposity index in normal-weight and obese rats and an increase in the functional capacity of trained obese rats. Level of Evidence III; Therapeutic Studies - Outcome Investigation. Case study – control.

Exercise Training Attenuates Cirrhotic Cardiomyopathy

Cirrhotic cardiomyopathy is a condition where liver cirrhosis is associated with cardiac dysfunction. Triggers and blockers of cirrhotic cardiomyopathy are poorly understood, which might compromise the prognosis of chronic liver disease patients. We tested whether exercise training would reduce liver damage induced by thioacetamide and prevent liver cirrhosis-associated cardiomyopathy. Wistar rats were divided into three groups: control, thioacetamide (TAA), or TAA plus exercise. Thioacetamide increased liver weight and serum alanine aminotransferase and aspartate aminotransferase levels. Also, TAA treatment was involved with hepatic nodule formation, fibrotic septa, inflammatory infiltration, and hepatocyte necrosis. The exercise group presented with a reduction in liver injury status. We found that liver injury was associated with disordered cardiac hypertrophy as well as diastolic and systolic dysfunction. Exercise training attenuated cirrhosis-associated cardiac remodeling and diastolic dysfunction and prevented systolic impairment. These results provided insights that exercise training can mitigate cirrhotic cardiomyopathy phenotype. Graphical Abstract Exercise training attenuated liver injury as well as cirrhosis-associated cardiac remodeling and diastolic dysfunction and prevented systolic impairment.

Isolated obesity resistance condition or associated with aerobic exercise training does not promote cardiac impairment

Mechanisms involved in cardiac function and calcium (Ca²⁺) handling in obese-resistant (OR) rats are still poorly determined. We tested the hypothesis that unsaturated high-fat diet (HFD) promotes myocardial dysfunction in OR rats, which it is related to Ca²⁺ handling. In addition, we questioned whether exercise training (ET) becomes a therapeutic strategy. Male Wistar rats (n=80) were randomized to standard or HFD diets for 20 weeks. The rats were redistributed for the absence or presence of ET and OR: control (C; n=12), control + ET (CET; n=14), obese-resistant (OR; n=9), and obese-resistant + ET (ORET; n=10). Trained rats were subjected to aerobic training protocol with progressive intensity (55-70% of the maximum running speed) and duration (15 to 60 min/day) for 12 weeks. Nutritional, metabolic, and cardiovascular parameters were determined. Cardiac function and Ca²⁺ handling tests were performed in isolated left ventricle (LV) papillary muscle. OR rats showed cardiac atrophy with reduced collagen levels, but there was myocardial dysfunction. ET was efficient in improving most parameters of body composition. However, the mechanical properties and Ca²⁺ handling from isolated papillary muscle were similar among groups. Aerobic ET does not promote morphological and cardiac functional adaptation under the condition of OR.

Myocardial Dysfunction in Cirrhotic Cardiomyopathy is Associated with Alterations of Phospholamban Phosphorylation and IL-6 Levels

BACKGROUND

Decreased cardiac contractility has been observed in cirrhosis, but the mechanisms that initiate and maintain cardiac dysfunction are not entirely understood.

AIM OF THE STUDY

We test the hypothesis that cirrhotic cardiomyopathy is related to deterioration of myocardial contractility due to alterations in calcium-handling proteins expression. In addition, we evaluated whether cardiac pro-inflammatory cytokine levels are associated with this process.

METHODS

Cirrhosis was induced by thioacetamide (TAA, 100 mg/kg/i.p., twice weekly for eight weeks). The myocardial performance was evaluated in isolated left ventricle papillary muscles under basal conditions and after inotropic challenge. The cardiac calcium handling protein expression was detected by Western blotting. Cardiac TNF-α and IL-6 levels were measured by ELISA.

RESULTS

Thioacetamide induced liver cirrhosis, which was associated with cirrhotic cardiomyopathy characterized by in vivo left ventricular diastolic and systolic dysfunction as well as cardiac hypertrophy. In vitro baseline myocardial contractility was lower in cirrhosis. Also, myocardial responsiveness to post-rest contraction stimulus was declined. Protein expression for RYR2, SERCA2, NCX, pPBL Ser¹⁶ and L-type calcium channel was quantitatively unchanged; however, pPBL Thr¹⁷ was significantly lower while IL-6 was higher.

CONCLUSIONS

Our study demonstrates that cirrhotic cardiomyopathy is associated with decreased cardiac contractility with alteration of phospholamban phosphorylation in association with higher cardiac pro-inflammatory IL-6 levels. These findings provided molecular and functional insights about the effects of liver cirrhosis on cardiac function.

AT1Receptor Blockade Improves Myocardial Functional Performance in Obesity

Fundamento

A obesidade tem sido associada com ativação crônica do sistema renina-angiotensina-aldosterona e importantes alterações no desempenho cardíaco.

Objetivo

Avaliar a influência do bloqueio de receptores de angiotensina-II do tipo 1 (AT₁) sobre a morfologia e desempenho cardíaco de ratos obesos por dieta

Métodos

Ratos Wistar (n=48) foram submetidos a dieta controle (2,9 kcal/g) ou hiperlipídica (3,6 kcal/g) durante 20 semanas. Após a 16ª semana, foram distribuídos em quatro grupos: Controle (CO), Obeso (OB), Controle Losartan (CL) e Obeso Losartan (OL). CL e OL receberam losartan (30 mg/kg/dia) na água durante quatro semanas. Posteriormente, foram analisadas composição corporal, pressão arterial sistólica (PAS) e ecocardiograma. A função de músculos papilares foi avaliada em situação basal com concentração de cálcio ([Ca²⁺]_o) de 2,50 mM e após manobras inotrópicas: potencial pós-pausa (PPP), elevação da [Ca²⁺]_o e durante estimulação beta-adrenérgica com isoproterenol. A análise dos resultados foi feita por meio de Two-Way ANOVA e teste de comparações apropriado. O nível de significância considerado foi de 5%.

Resultados

Embora a alteração da PAS não tenha se mantido ao final do experimento, a obesidade se associou com hipertrofia cardíaca e maior velocidade de encurtamento da parede posterior do ventrículo esquerdo.No estudo de músculos papilares em condição basal, CL mostrou menor velocidade máxima de variação negativa da tensão desenvolvida (-dT/dt) do que CO. O PPP de 60s promoveu menor -dT/dt e pico de tensão desenvolvida (TD) em OB e CL, comparados ao CO, e maior variação relativa de TD e velocidade máxima de variação positiva (+dT/dt) no OL em relação a CL e OB. Sob 1,5, 2,0 e 2,5mM de [Ca²⁺]_o, o grupo OL exibiu maior -dT/dt do que CL.

Conclusão

Losartan melhora a função miocárdica de ratos com obesidade induzida por dieta. (Arq Bras Cardiol. 2020; 115(1):17-28)

Resistance training promotes reduction in Visceral Adiposity without improvements in Cardiomyocyte Contractility and Calcium handling in Obese Rats

Resistance training (RT) improves the cardiomyocyte calcium (Ca²⁺) cycling during excitation-contraction coupling. However, the role of RT in cardiomyocyte contractile function associated with Ca²⁺ handling in obesity is unclear. Wistar rats were distributed into four groups: control, sedentary obese, control plus RT, and obesity plus RT. The 10-wk RT protocol was used (4-5 vertical ladder climbs, 60-second interval, 3× a week, 50-100% of maximum load). Metabolic, hormonal, cardiovascular and biochemical parameters were determined. Reduced leptin levels, epididymal, retroperitoneal and visceral fat pads, lower body fat, and adiposity index were observed in RT. Obesity promoted elevation of collagen, but RT did not promote modifications of LV collagen in ObRT. RT induced elevation in maximum rates of contraction and relaxation, and reduction of time to 50% relaxation. ObRT group did not present improvement in the cardiomyocyte contractile function in comparison to Ob group. Reduced cardiac PLB serine¹⁶ phosphorylation (pPLB Ser¹⁶) and pPLB Ser¹⁶/PLB ratio with no alterations in sarcoplasmic reticulum Ca²⁺ ATPase (SERCA2a) and phospholamban (PLB) expression were observed in Ob groups. Resistance training improved body composition reduced fat pads and plasma leptin levels but did not promote positive alterations in cardiomyocyte contractile function, Ca²⁺ handling and phospholamban phosphorylation.

Exercise does not ameliorate cardiac dysfunction in obese mice exposed to fine particulate matter

BACKGROUND

Studies have demonstrated that exposure to fine particulate matter (PM_2.5) is linked to cardiovascular disease (CVD), which is exacerbated in patients with pre-existing conditions such as obesity. In the present study, we examined cardiac function of obese mice exposed to PM_2.5 and determined if mild exercise affected cardiac function.

METHODS

Obese mice (ob/ob) (leptin deficient, C57BL/6J background) were exposed to either filtered air (FA) or PM_2.5 at an average concentration of 32 μg/m³ for 6 h/day, 5 days/week for 9 months. Following exposure, mice were divided into four groups: (1) FA sedentary, (2) FA treadmill exercise, (3) PM_2.5 sedentary, and (4) PM_2.5 treadmill exercise and all mice were analyzed after 8 weeks of exercise training.

RESULTS

Echocardiography showed increased left ventricular end systolic (LVESd) and diastolic (LVEDd) diameters in PM_2.5 sedentary mice compared to FA sedentary mice. There was increased expression of ICAM1, VCAM and CRP markers in sedentary PM_2.5 mice compared to FA mice. Both FA and PM_2.5 exercised mice showed decreased posterior wall thickness in systole compared to FA sedentary mice, coupled with altered expression of inflammatory markers following exercise.

CONCLUSION

Obese mice exposed to PM_2.5 for 9 months showed cardiac dysfunction, which was not improved following mild exercise training.

Differential Effects of High Sugar, High Lard or a Combination of Both on Nutritional, Hormonal and Cardiovascular Metabolic Profiles of Rodents

BACKGROUND

Dietary interventions in rodents can induce an excess of adipose tissue and metabolic disorders that resemble human obesity. Nevertheless, these approaches are not standardized, and the phenotypes may vary distinctly among studies. The aim of this study was to investigate the effects of different dietary interventions on nutritional, metabolic, biochemical, hormonal, and cardiovascular profiles, as well as to add to development and characterization of an experimental model of obesity.

METHODS

Male Wistar rats were randomized into four groups: control diet (C), high-sugar (HS), high-fat (HF), or high-sugar and high-fat (HFHS). Weekly measurements of body weight, adiposity, area under the curve (AUC) for glucose, blood pressure (BP) and serum triglycerides, total cholesterol level, and leptin were performed.

RESULTS

HF and HFHS models were led to obesity by increases in adipose tissue deposition and the adiposity index. All hypercaloric diets presented systolic BP increases. In addition, the AUC for glucose was greater in HF and HFHS than in C, and only the HF group presented hyperleptinemia.

CONCLUSIONS

HF and HFHS diet approaches promote obesity and comorbidities, and thus represent a useful tool for studying human obesity-related disorders. By contrast, the HS model did not prove to be a good model of obesity.

Moderate exercise training does not prevent the reduction in myocardial L-type Ca2+ channels protein expression at obese rats

Authors have showed that obesity implicates cardiac dysfunction associated with myocardial L-type calcium channels (LTCCs) activity impairments, as well as moderate exercise training (MET) seems to be an important therapeutic tool. We tested the hypothesis that MET promotes improvements on LTCCS activity and protein expression at obesity induced by unsaturated high-fat diets, which could represent a protective effects against development of cardiovascular damage. Male Wistar rats were randomized in control (C, n = 40), which received a standard diet and obese (Ob; n = 40), which received high-fat diet. After 20 weeks, the animals were assigned at four groups: control (C; n = 12); control submitted to exercise training (ET; n = 14); obese (Ob; n = 10); and obese submitted to exercise training (ObET; n = 11). ET (5 days/week during 12 weeks) began in the 21th week and consisted of treadmill running that was progressively increased to reach 60 min. Final body weight (FBW), body fat (BF), adiposity index (AI), comorbidities, and hormones were evaluated. Cardiac remodeling was assessed by morphological and isolated papillary muscles function. LTCCs activity was determined using specific blocker, while protein expression of LTCCs was evaluated by Western blot. Unsaturated high-fat diet promoted obesity during all experimental protocol. MET controlled obesity process by decreasing of FBW, BF, and AI. Obesity implicated to LTCCs protein expression reduction and MET was not effective to prevent this condition. ET was efficient to promote several improvements to body composition and metabolic parameters; however, it was not able to prevent or reverse the downregulation of LTCCs protein expression at obese rats.