Grape polyphenols and exercise training have distinct molecular effects on cardiac hypertrophy in a model of obese insulin-resistant rats.

Obesity and exercise lead to structural changes in heart such as cardiac hypertrophy. The underlying signaling pathways vary according to the source of the overload, be it physiological (exercise) or pathologic (obesity). The physiological pathway relies more on PI3K-Akt signaling while the pathologic pathway involves calcineurin-Nuclear factor of activated T-cells activation and fibrosis accumulation. Independently, exercise and polyphenols have demonstrated to prevent pathologic cardiac hypertrophy. Therefore, we investigated the molecular adaptations of the combination of exercise training and grape polyphenols supplementation (EXOPP) in obese high-fat fed rats on heart adaptation in comparison to exercise (EXO), polyphenols supplementation (PP) and high-fat fed rats (HF), alone. Exercised and PP rats presented a higher heart weight/body weight ratio compared to HF rats. EXO and EXOPP depicted an increase in cell-surface area, P-Akt/Akt, P-AMPK/AMPK ratios with a decreased fibrosis and calcineurin expression, illustrating an activation of the physiological pathway, but no additional benefit of the combination. In contrast, neither cell-surface area nor Akt signaling increased in PP rats; but markedly decreased fibrosis, calcineurin expression, systolic blood pressure, higher SERCA and P-Phospholamdan/Phospholamdan levels were observed. These data suggest that PP rats have a shift from pathologic toward physiological hypertrophy. Our study demonstrates that polyphenols supplementation has physical-activity-status-specific effects; it appears to be more protective in sedentary obese insulin-resistant rats than in the exercised ones. Exercise training improved metabolic and cardiac alterations without a synergistic effect of polyphenols supplementation. These data highlight a greater effect of exercise than polyphenols supplementation for the treatment of cardiac alterations in obese insulin-resistant rats.

Dietary Supplementation with Silicon-Enriched Spirulina Improves Arterial Remodeling and Function in Hypertensive Rats.

Vascular aging is characterized by increase in arterial stiffness and remodeling of the arterial wall with a loss of elastic properties. Silicon is an essential trace element highly present in arteries. It is involved in the constitution and stabilization of elastin fibers. The nutritional supply and bioavailability of silicon are often inadequate. Spirulina (Sp), micro algae have recognized nutritional properties and are able to incorporate minerals in a bioavailable form. We evaluated the effects of nutritional supplementation with silicon-enriched spirulina (SpSi) on arterial system structure and function in hypertension. Experiments were performed on hypertensive (SHR) and normotensive Wistar-Kyoto (WKY) rats supplemented with SpSi or Sp over a period of three months. Arterial pressure, vascular function and morphometric parameters of thoracic aorta were analyzed. SpSi supplementation lowered arterial pressure in SHR and minimized morphometric alterations induced by hypertension. Aortic wall thickness and elastic fibers fragmentation were partially reversed. Collagen and elastin levels were increased in association with extracellular matrix degradation decrease. Vascular reactivity was improved with better contractile and vasorelaxant responses to various agonists. No changes were observed in SHR supplemented with Sp. The beneficial effects of SpSi supplementation evidenced here, may be attributable to Si enrichment and offer interesting opportunities to prevent cardiovascular risks.

Dietary silicon-enriched spirulina improves early atherosclerosis markers in hamsters on a high-fat diet.

OBJECTIVE: The aim of this study was to investigate the effects of dietary silicon-enriched spirulina (SES) on atherosclerosis. METHODS: Hamsters (six per group) on a high-fat (HF) diet received SES or non-enriched spirulina (both at 57 mg/kg body weight) daily. This corresponded to 0.57 mg silicon/kg body weight daily. RESULTS: The HF diet induced dyslipidemia, insulin resistance, oxidative stress, and vascular dysfunction. Compared with the HF group, SES attenuated increases of lipemia and prevented insulin resistance (IR) (P = 0.001). SES protected against oxidative stress through a reduction of heart (P = 0.006) and liver (P < 0.0001) nicotinamide adenine dinucleotide phosphate-oxidase activity and by sparing the activity of superoxide dismutase (P = 0.0017) and glutathione peroxidase (P = 0.01861). SES decreased inflammation, lowering tumor necrosis factor-α (P = 0.0006) and interleukin-6 levels (P = 0.0112), decreasing polymorphonuclear cells and preventing nuclear factor-κB activity (P = 0.0259). SES corrected plasma level of monocyte chemoattractant protein-1 (P = 0.0380), which was increased by the HF diet. Finally, SES supplementation prevented vascular and endothelial functions assessed respectively by the contractile response to the agonist phenylephrine and the relaxation induced by acetylcholine. CONCLUSION: SES protects against metabolic imbalance, inflammation, oxidative stress, and vascular dysfunction induced by an HF diet, and could prevent the atherogenic processes. Synergistic effects between spirulina and silicon were observed.