Skeletal muscle insulin resistance and adipose tissue hypertrophy persist beyond the reshaping of gut microbiota in young rats fed a fructose-rich diet

Low-intensity exercise prevents cardiac inflammation through the NF-κB/TNFα pathway in insulin-resistant male rats

Our previously published results have proven that low-intensity exercise, equivalent to brisk walking, is beneficial in managing cardiac insulin resistance in post-weaning male rats exposed to a fructose-rich diet. Still, its role in protecting against cardiac inflammation is unclear. This experiment was designed to investigate the preventive effect of low-intensity exercise on cardiac inflammation in male post-weaning rats exposed to a fructose-rich diet (10%). Male Wistar rats were randomly assigned to a sedentary control group, a sedentary group with fructose overload, and a fructose overload group subjected to treadmill exercise for nine weeks. Protein expression of cardiac inducible nitric oxide synthase (iNOS), matrix metalloproteinase 9, as well as cellular localization/phosphorylation of nuclear factor kappa B (NF-κB), and α1 and α2 subunits of sodium-potassium ATPase pump (Na/K-ATPase) was determined. Additionally, gene expression of tumor necrosis factor α (TNFα) and suppressor of cytokine signaling 3 (SOCS3) was examined. The results demonstrate that a chronic fructose-rich diet in sedentary rats elevates the expression of key inflammatory markers, including SOCS3, TNFα, NF-κB, and iNOS, as well as the plasma membrane α1 and α2 subunits. Exercise prevented alterations induced by a fructose-rich diet, except iNOS expression. Additionally, exercise increased the protein expression of the α1 and α2 subunits of Na/K-ATPase in the lysate of fructose-fed rats. These findings suggest that low-intensity exercise is an effective non-invasive strategy for cardioprotection, helping to prevent inflammation by modulating TNFα and NF-κB expression in insulin-resistant hearts of post-weaning male rats.

Fructose-Induced Impairment of Liver and Skeletal Muscle Metabolism Is Prevented by Administration of Shouchella clausii Spores by Preserving Mitochondrial Function and Insulin Sensitivity

The objective of the study was to evaluate the efficacy of S. clausii spores (SF174) in counteracting the deleterious effects of dietary fructose. Thirty-days old male Wistar rats were treated for 6 weeks: control group: 0.5 mL of 10% sucrose solution (without probiotics); fructose group: 0.5 mL of 10% sucrose solution + high-fructose diet (without probiotics); SF174 group: 0.5 mL of 10% sucrose solution containing SF174 (5 × 10⁹ CFU) + high-fructose diet. Fructose intake induced an increase in proinflammatory cytokines in portal plasma, liver, and skeletal muscle, a decrease in insulin sensitivity in both tissues and a condition of hepatic steatosis. An increase in the mitochondrial activity in the liver and a decrease in skeletal muscle were evidenced, together with an increase in the thiobarbituric acid reactive substances (TBARS) levels and a decrease in the antioxidant enzyme activity. All the above alterations were counteracted by probiotic administration. We here demonstrate for the first time that S. clausii SF174 counteracts low-grade inflammation and insulin resistance induced by fructose, protects mitochondria from changes in oxidative capacity, and maintains unaltered the oxidative balance. Therefore, S. clausii SF174 administration can be an effective strategy to prevent the unhealthy consequences of dietary fructose.

Protective role of cells and spores of Shouchella clausii SF174 against fructose-induced gut dysfunctions in small and large intestine

The oral administration of probiotics is nowadays recognized as a strategy to treat or prevent the consequences of unhealthy dietary habits. Here we analyze and compare the effects of the oral administration of vegetative cells or spores of Shouchella clausii SF174 in counteracting gut dysfunctions induced by 6 weeks of high fructose intake in a rat model. Gut microbiota composition, tight junction proteins, markers of inflammation and redox homeostasis were evaluated in ileum and colon in rats fed fructose rich diet and supplemented with cells or spores of Shouchella clausii SF174. Our results show that both spores and cells of SF174 were effective in preventing the fructose-induced metabolic damage to the gut, namely establishment of "leaky gut", inflammation and oxidative damage, thus preserving gut function. Our results also suggest that vegetative cells and germination-derived cells metabolize part of the ingested fructose at the ileum level.

The Impact of Excessive Fructose Intake on Adipose Tissue and the Development of Childhood Obesity

Worldwide, childhood obesity cases continue to rise, and its prevalence is known to increase the risk of non-communicable diseases typically found in adults, such as cardiovascular disease and type 2 diabetes mellitus. Thus, comprehending its multiple causes to build healthier approaches and revert this scenario is urgent. Obesity development is strongly associated with high fructose intake since the excessive consumption of this highly lipogenic sugar leads to white fat accumulation and causes white adipose tissue (WAT) inflammation, oxidative stress, and dysregulated adipokine release. Unfortunately, the global consumption of fructose has increased dramatically in recent years, which is associated with the fact that fructose is not always evident to consumers, as it is commonly added as a sweetener in food and sugar-sweetened beverages (SSB). Therefore, here, we discuss the impact of excessive fructose intake on adipose tissue biology, its contribution to childhood obesity, and current strategies for reducing high fructose and/or free sugar intake. To achieve such reductions, we conclude that it is important that the population has access to reliable information about food ingredients via food labels. Consumers also need scientific education to understand potential health risks to themselves and their children.

Short-term fructose feeding alters tissue metabolic pathways by modulating microRNAs expression both in young and adult rats

Dietary high fructose (HFrD) is known as a metabolic disruptor contributing to the development of obesity, diabetes, and dyslipidemia. Children are more sensitive to sugar than adults due to the distinct metabolic profile, therefore it is especially relevant to study the metabolic alterations induced by HFrD and the mechanisms underlying such changes in animal models of different ages. Emerging research suggests the fundamental role of epigenetic factors such as microRNAs (miRNAs) in metabolic tissue injury. In this perspective, the aim of the present study was to investigate the involvement of miR-122-5p, miR-34a-5p, and miR-125b-5p examining the effects induced by fructose overconsumption and to evaluate whether a differential miRNA regulation exists between young and adult animals. We used young rats (30 days) and adult rats (90 days) fed on HFrD for a short period (2 weeks) as animal models. The results indicate that both young and adult rats fed on HFrD exhibit an increase in systemic oxidative stress, the establishment of an inflammatory state, and metabolic perturbations involving the relevant miRNAs and their axes. In the skeletal muscle of adult rats, HFrD impair insulin sensitivity and triglyceride accumulation affecting the miR-122-5p/PTP1B/P-IRS-1(Tyr612) axis. In liver and skeletal muscle, HFrD acts on miR-34a-5p/SIRT-1: AMPK pathway resulting in a decrease of fat oxidation and an increase in fat synthesis. In addition, liver and skeletal muscle of young and adult rats exhibit an imbalance in antioxidant enzyme. Finally, HFrD modulates miR-125b-5p expression levels in liver and white adipose tissue determining modifications in de novo lipogenesis. Therefore, miRNA modulation displays a specific tissue trend indicative of a regulatory network that contributes in targeting genes of various pathways, subsequently yielding extensive effects on cell metabolism.