Long-term abdominal adiposity activates several parameters of cardiac energy function

An experimental model of western diet in female Wistar rats leads to cardiac hypoxia related to a stimulated contractility

Previous studies in Western diet (WD)-fed male rats have highlighted a link between the stimulation of cardiac contractility, mitochondrial adaptations and a pro-inflammatory fatty acid profile of phospholipids in the heart. Our objectives were to determine (1) if WD-fed female Wistar rats and obese humans display a similar pro-inflammatory profile in their cardiac phospholipids and (2) if this lipid profile is associated with deleterious effects on the heart of the female rodents. Female Wistar rats were fed WD for 5 weeks or a laboratory chow as a control. Ionic homeostasis, redox status, inflammation markers, and fatty acid composition of phospholipids were analysed in the heart. WD increased the abdominal fat mass without modifying the body weight of female rats. As previously found in males, a WD induced a shift in membrane fatty acid composition toward a pro-inflammatory profile in the female rats, but not in obese humans. It was associated with an increased COX2 expression suggesting an increased pro-inflammatory eicosanoid production. Signs of increased intracellular calcium strongly supported a stimulation of cardiac contractility without any induction of apoptosis. The heart of WD-fed rats exhibited a hypoxic state as a higher HIF1-α expression was reported. The expressions of antioxidant enzymes were increased, but the redox reserves against reactive oxygen species were lowered. In conclusion, as previously observed in males, we suppose that cardiac abnormalities are magnified with severe obesity in female rats, leading to hypoxia and intense oxidative stress which could ultimately induce cell death and heart failure.

Relationship Between Metabolic Syndrome and Cognitive Function: A Population-Based Study of Middle-Aged and Elderly Adults in Rural China

INTRODUCTION

To explore the relationship between metabolic syndrome (MetS) and cognitive impairment in a low-income and low-education population.

METHODS

All residents aged ≥45 years in a low-income population in Tianjin, China, were eligible to participate in this study. The Mini-Mental State Examination (MMSE) scale was used to conduct a preliminary screening and assessment of the participants' cognitive statuses. The MMSE components are orientation, registration, attention and calculation, recall, and language.

RESULTS

In this population, the prevalences of MetS and cognitive impairment were 54.1% and 44.5%, respectively. In the overall population, the registration score was 0.105 points lower in the elevated triglycerides (TG) group than in the normal TG group (β, -0.105; 95% confidence interval [CI]: -0.201, -0.010; P=0.030). In men, high TG was associated with registration scores that were 0.152 points lower than those in the normal TG group (95% CI: -0.281, -0.022; P=0.022), while larger WC and lower HDL-C had positive effects on cognitive scores (all P<0.05). However, in women, there were no significant differences between cognitive scores and MetS or its components.

CONCLUSION

In this population, first, TG had a great impact on cognition, even greater than the impact of MetS on cognition. Second, the impact of MetS components on cognition was more obvious in men, and not all of the effects were negative. Therefore, the effect of MetS on cognition may need to be analyzed separately for different populations, and it may be that the effect of a single component is greater than the overall effect. When formulating prevention strategies for cognitive impairments, population differences must also be taken into consideration.

A procedure to extract functional isolated mitochondria from small-sized human atrial samples. Application to obesity with a partial characterisation of the organelles

Evaluating the activity of cardiac mitochondria is probably the best way to estimate early cellular damage in chronic pathology. Early diagnosis allows rapid therapeutic intervention thus increasing patient survival rate in a number of diseases. However, data on human cardiac mitochondria are scarce in the international literature. Here, we describe a method to extract and study functional mitochondria from the small-sized right atrial aliquots (minimum of 400 mg) obtained during extracorporeal circulation and usually considered as surgical waste products. The mitochondria were purified through several mechanical processes (fine myocardial cutting, tissue grinding and potter Elvehjem homogenising), an enzymatic proteolytic action (subtilisin) and differential centrifugations. In chronic pathologies, including obesity, early disturbances of mitochondrial function can occur. The effects of obesity on the rate of mitochondrial oxygen consumption and H₂O₂ release were thus determined with three different substrates (glutamate/malate, succinate/rotenone and palmitoylcarnitine/malate). The human atrial mitochondria were of high quality from a functional viewpoint, compared to rat ventricle organelles, but the extraction yield of the human mitochondria was twice lower than that of rat mitochondria. Tests showed that glutamate/malate-related ADP-stimulated respiration was strongly increased in obese subjects, although the oxidation of the other two substrates was unaffected. Reactive oxygen species (ROS) production by the isolated mitochondria was low in comparison with that of the lean subjects. These results confirm those found in one of our previous studies in the ventricles of rats fed a high-fat diet. In conclusion, the described method is simple, reliable and sensitive. It allows for the description of the impact of obesity on the function of atrial mitochondria while using only a small patient sampling (n = 5 in both the lean and the obese groups).

Dietary EPA Increases Rat Mortality in Diabetes Mellitus, A Phenomenon Which Is Compensated by Green Tea Extract

Diabetes is characterized by a high mortality rate which is often associated with heart failure. Green tea and eicosapentaenoic acid (EPA) are known to lessen some of the harmful impacts of diabetes and to exert cardio-protection. The aim of the study was to determine the effects of EPA, green tea extract (GTE), and a combination of both on the cardiac consequences of diabetes mellitus, induced in Wistar rats by injection of a low dose of streptozotocin (33 mg/kg) combined with a high fat diet. Cardiac mechanical function, coronary reactivity, and parameters of oxidative stress, inflammation, and energy metabolism were evaluated. In the context of diabetes, GTE alone limited several diabetes-related symptoms such as inflammation. It also slightly improved coronary reactivity and considerably enhanced lipid metabolism. EPA alone caused the rapid death of the animals, but this effect was negated by the addition of GTE in the diet. EPA and GTE combined enhanced coronary reactivity considerably more than GTE alone. In a context of significant oxidative stress such as during diabetes mellitus, EPA enrichment constitutes a risk factor for animal survival. It is essential to associate it with the antioxidants contained in GTE in order to decrease mortality rate and preserve cardiac function.

Cardiac mitochondrial respiration following a low-carbohydrate, high-fat diet in apolipoprotein E-deficient mice

Low-carbohydrate diets are considered to be an effective approach to weight loss and have, subsequently, grown in popularity. Despite the apparent health benefits that these diets may provide for insulin resistance, hypertension, and dyslipidemia, their implications on cardiomyocyte oxidative capacity have yet to be investigated. To evaluate the adaptations induced by a 6-week low-carbohydrate, high-fat (LCHF) diet on mitochondrial respiration, two groups of male mice were investigated: Apolipoprotein E-deficient mice on a LCHF diet (L-DIET) and apolipoprotein E-deficient mice on a regular rodent diet (CON). Heart tissue was extracted and used for high-resolution respirometry (HRR), while immunoblotting was performed to quantify mitochondrial density and complexes. The results demonstrate increased expression of all five mitochondrial subunits in the L-DIET group compared to control condition. Furthermore, HRR revealed increased efficiency of substrate consumption, implying augmented oxidative capacity in the L-DIET group. These findings further support the notion that cardiomyocytes prefer lipids as a primary fuel source, by demonstrating that the shift in metabolism caused by a LCHF diet facilitates such an environment. This provides important information regarding the effects of a LCHF on cardiomyocytes, especially when considering free radical production and heart dysfunction.

Obesity Paradox in Aging: From Prevalence to Pathophysiology

Recent advances in medical technology and health care have greatly improved the management for chronic diseases and prolonged human lifespan. Unfortunately, increased lifespan and the aging population impose a major challenge on the ever-rising prevalence of chronic diseases, in particular cardiometabolic stress associated with the pandemic obesity in our modern society. Although overweight and obesity are associated with incident cardiovascular diseases (CVD), including heart failure (HF), it paradoxically leads to a more favorable prognosis in patients with chronic HF, a phenomenon commonly defined as "obesity paradox". Numerous population-based and clinical studies have suggested possible explanations such as better metabolic reserve, smoking and disease-associated weight loss for obesity paradox. Recent evidence noticed a shift in obesity paradox with aging. While some studies have reported a more pronounced "obesity paradox" in the older patients, others have seen diminished cardiac benefits with overweight and obesity in the elderly patients with CVD. These findings suggested that a complex relationship among aging, metabolism, and HF severity/chronicity, which may explain the shift in obesity paradox in the elderly. Aging negatively affects body metabolism and cardiac function although its precise impact on obesity paradox remains elusive. To develop new strategies for cardiovascular health in the elderly, it is imperative to understand the precise role for aging on obesity-related CVD.