Muscular resistance, hypertrophy and strength training equally reduce adiposity, inflammation and insulin resistance in mice with diet-induced obesity

Strength Training Protects High-Fat-Fed Ovariectomized Mice against Insulin Resistance and Hepatic Steatosis

Menopause is characterized by a reduction in sex hormones in women and is associated with metabolic changes, including fatty liver and insulin resistance. Lifestyle changes, including a balanced diet and physical exercise, are necessary to prevent these undesirable changes. Strength training (ST) has been widely used because of the muscle and metabolic benefits it provides. Our study aims to evaluate the effects of ST on hepatic steatosis and insulin resistance in ovariectomized mice fed a high-fat diet (HFD) divided into four groups as follows: simulated sedentary surgery (SHAM-SED), trained simulated surgery (SHAM-EXE), sedentary ovariectomy (OVX-SED), and trained ovariectomy (OVX-EXE). They were fed an HFD for 9 weeks. ST was performed thrice a week. ST efficiently reduced body weight and fat percentage and increased lean mass in OVX mice. Furthermore, ST reduced the accumulation of ectopic hepatic lipids, increased AMPK phosphorylation, and inhibited the de novo lipogenesis pathway. OVX-EXE mice also showed a better glycemic profile, associated with greater insulin sensitivity identified by the euglycemic-hyperinsulinemic clamp, and reduced markers of hepatic oxidative stress compared with sedentary animals. Our data support the idea that ST can be indicated as a non-pharmacological treatment approach to mitigate metabolic changes resulting from menopause.

Time-restricted feeding combined with resistance exercise prevents obesity and improves lipid metabolism in the liver of mice fed a high-fat diet

Nonalcoholic fatty liver disease (NAFLD), a condition characterized by the accumulation of fat in the liver, is estimated to be the most common liver disease worldwide. Obesity is a major risk factor and contributor, and, accordingly, weight loss can improve NAFLD. Previous studies in preclinical models of diet-induced obesity and fatty liver disease have shown the independent benefits of resistance exercise training (RT) and time-restricted feeding (TRF) in preventing weight gain and hepatic build-up of fat. Here, we tested the combined effect of TRF and RT on obesity and NAFLD in mice fed a high-fat diet. Our results showed that both TRF-8-h food access in the active phase-and RT-consisting of three weekly sessions of ladder climbing-attenuated body weight gain, improved glycemic homeostasis, and decreased the accumulation of lipids in the liver. TRF combined with RT improved the respiratory exchange rate, energy expenditure, and mitochondrial respiration in the liver. Furthermore, gene expression analysis in the liver revealed lower mRNA expression of lipogenesis and inflammation genes along with increased mRNA of fatty acid oxidation genes in the TRF + RT group. Importantly, combined TRF + RT was shown to be more efficient in preventing obesity and metabolic disorders. In conclusion, TRF and RT exert complementary actions compared with isolated interventions, with significant effects on metabolic disorders and NAFLD in mice.NEW & NOTEWORTHY Whether time-restricted feeding (TRF) combined with resistance exercise training (RT) may be more efficient compared with these interventions alone is still unclear. We show that when combined with RT, TRF provided additional benefits, being more effective in increasing energy expenditure, preventing weight gain, and regulating glycemic homeostasis than each intervention alone. Thus, our results demonstrate that TRF and RT have complementary actions on some synergistic pathways that prevented obesity and hepatic liver accumulation.

Resistance Training Modulates Hippocampal Neuroinflammation and Protects Anxiety-Depression-like Dyad Induced by an Emotional Single Prolonged Stress Model

Stress is a triggering factor for anxious and depressive phenotypes. Exercise is known for its action on the central nervous system. This study aimed to evaluate the role of resistance exercise in an anxiety-depression-like dyad in a model of stress. Male Swiss mice (35-day-old) were exercised, three times a week for 4 weeks on nonconsecutive days. The resistance exercise consisted of climbing a 1-m-high ladder 15 times. After mice were subjected to an emotional single prolonged stress (Esps) protocol. Seven days later, they were subjected to anxiety and depression predictive behavioral tests. The results showed that exercised mice gain less weight than sedentary from weeks 3 to 5. Resistance exercise was effective against an increase in immobility time in the forced swim test and tail suspension test and a decrease in grooming time of mice subjected to Esps. Resistance exercise protected against the decrease in the percentage of open arms time and open arm entries, and the increase in the anxiety index in Esps mice. Four-week resistance exercise did not elicit an antidepressant/anxiolytic phenotype in non-stressed mice. Esps did not alter plasma corticosterone levels but increased the hippocampal glucocorticoid receptor content in mice. Resistance exercise protected against the decrease in hippocampal levels of tropomyosin kinase B (TRκB), the p-Akt/Akt, and the p-mTOR/mTOR ratios of Esps mice. Resistance exercise proved to be effective in decreasing hippocampal neuroinflammation in Esps mice. Resistance exercise protected against the increase in the hippocampal Akt/mTOR pathway and neuroinflammation, and anxiety/depression-like dyad in Esps exposed mice.

Effects of the association of different volumes of strength training with photobiomodulation therapy on insulin resistance: A protocol for a randomized, triple-blind, placebo-controlled trial

Background

Insulin resistance (IR) is the main risk factor for developing type 2 diabetes. Both strength training (ST) and photobiomodulation therapy (PBMt) reduce IR, but the effect of combining different volumes of ST with PBMt is unknown.

Methods

Overweight/obese individuals will be assigned to 4 groups (n = 12/group): ST with volume following international guidelines (3 sets per exercise - high volume) or one-third of this volume (1 set per exercise - low volume), combined with PBMt or placebo. ST will be performed for 20 sessions over 10 weeks and will consist of 7 exercises. The PBMt will be applied after training sessions using blankets with light emitters (LEDs) placed over the skin on the frontal and the posterior region of the body, following the parameters recommended by the literature. The placebo group will undergo an identical procedure, but blankets will emit insignificant light. To measure plasma glucose and insulin concentrations, oral glucose tolerance tests (OGTT) will be performed before and after the training period. Thereafter, IR, the area under the curve of glucose and insulin, and OGTT-derived indices of insulin sensitivity/resistance will be calculated.

Expected impact on the field

This study will determine the effects of different ST volumes on IR and whether the addition of PBMt potentiates the effects of ST. Because previously sedentary, obese, insulin-resistant individuals might not comply with recommended volumes of exercise, the possibility that adding PBMt to low-volume ST enhances ST effects on IR bears practical significance.

Aerobic Exercise Prevents Chronic Inflammation and Insulin Resistance in Skeletal Muscle of High-Fat Diet Mice

Obesity is commonly accompanied by chronic tissue inflammation and leads to insulin resistance. Aerobic exercise is an essential treatment for insulin resistance and has anti-inflammatory effects. However, the molecular mechanisms of exercise on obesity-associated inflammation and insulin resistance remain largely unknown. Here, we evaluated the effects of aerobic exercise on inflammation and insulin resistance in skeletal muscles of high-fat diet (HFD) mice. Male C57BL/6J mice were fed a high-fat diet or a normal diet for 12 weeks, and then aerobic training was performed on a treadmill for 8 weeks. Body weight, fasting blood glucose, food intake levels, and glucose and insulin tolerance were evaluated. The levels of cytokines, skeletal muscle insulin resistance, and inflammation were also analyzed. Eight weeks of aerobic exercise attenuated HFD-induced weight gain and glucose intolerance, and improved insulin sensitivity. This was accompanied by enhanced insulin signaling. Exercise directly resulted in a significant reduction of lipid content, inflammation, and macrophage infiltration in skeletal muscles. Moreover, exercise alleviated HFD-mediated inflammation by suppressing the activation of the NF-κB pathway within skeletal muscles. These results revealed that aerobic exercise could lead to an anti-inflammatory phenotype with protection from skeletal muscle insulin resistance in HFD-induced mice.

Assessment of stress and anxiety in mice with colorectal cancer submitted to physical exercise

PURPOSE

To evaluate the effect of physical exercise on the behavior of rodents with colorectal cancer induced through the use of elevated plus maze.

METHODS

We used 40 male hairless mice induced to colorectal cancer, divided into five groups: G1) submitted to pre- and post-induction swimming; G2) pre- and post-induction ladder; G3) post-induction swimming; G4) post-induction ladder; G5) sedentary. At the end of the 14th week, the animals were submitted to the plus maze test.

RESULTS

The mean length of stay in the open arm for G1 was 4.17 ± 6.50; G2 37.52 ± 40.7; G3 85.84 ± 42.5; G4 32.92 ± 23.17; and G5 4.09 ± 4.43. In the closed arm, it was 264 ± 23.43 in G1, 187.60 ± 47.73 in G2, 147.50 ± 40.03 in G3, 182.00 ± 40.40 in G4, and in G5 235.36 ± 14.28. In the center, G1 remained 31.86 ± 20.18, G2 74.85 ± 28.37, G3 66.69 ± 19.53, G4 60.55 ± 10.46, and G5 60.55 ± 23.65.

CONCLUSIONS

Aerobic exercise for seven weeks after tumor induction showed less impact on the behavior of the animals. On the other hand, it significantly increased the animals' stress level when applied for 14 weeks before and after tumor induction.

Trends in insulin resistance: insights into mechanisms and therapeutic strategy

The centenary of insulin discovery represents an important opportunity to transform diabetes from a fatal diagnosis into a medically manageable chronic condition. Insulin is a key peptide hormone and mediates the systemic glucose metabolism in different tissues. Insulin resistance (IR) is a disordered biological response for insulin stimulation through the disruption of different molecular pathways in target tissues. Acquired conditions and genetic factors have been implicated in IR. Recent genetic and biochemical studies suggest that the dysregulated metabolic mediators released by adipose tissue including adipokines, cytokines, chemokines, excess lipids and toxic lipid metabolites promote IR in other tissues. IR is associated with several groups of abnormal syndromes that include obesity, diabetes, metabolic dysfunction-associated fatty liver disease (MAFLD), cardiovascular disease, polycystic ovary syndrome (PCOS), and other abnormalities. Although no medication is specifically approved to treat IR, we summarized the lifestyle changes and pharmacological medications that have been used as efficient intervention to improve insulin sensitivity. Ultimately, the systematic discussion of complex mechanism will help to identify potential new targets and treat the closely associated metabolic syndrome of IR.

Healthy versus Unhealthy Adipose Tissue Expansion: the Role of Exercise

Although the hallmark of obesity is the expansion of adipose tissue, not all adipose tissue expansion is the same. Expansion of healthy adipose tissue is accompanied by adequate capillary angiogenesis and mitochondria-centered metabolic integrity, whereas expansion of unhealthy adipose tissue is associated with capillary and mitochondrial derangement, resulting in deposition of immune cells (M1-stage macrophages) and excess production of pro-inflammatory cytokines. Accumulation of these dysfunctional adipose tissues has been linked to the development of obesity comorbidities, such as type 2 diabetes, hypertension, dyslipidemia, and cardiovascular disease, which are leading causes of human mortality and morbidity in modern society. Mechanistically, vascular rarefaction and mitochondrial incompetency (for example, low mitochondrial content, fragmented mitochondria, defective mitochondrial respiratory function, and excess production of mitochondrial reactive oxygen species) are frequently observed in adipose tissue of obese patients. Recent studies have demonstrated that exercise is a potent behavioral intervention for preventing and reducing obesity and other metabolic diseases. However, our understanding of potential cellular mechanisms of exercise, which promote healthy adipose tissue expansion, is at the beginning stage. In this review, we hypothesize that exercise can induce unique physiological stimuli that can alter angiogenesis and mitochondrial remodeling in adipose tissues and ultimately promote the development and progression of healthy adipogenesis. We summarize recent reports on how regular exercise can impose differential processes that lead to the formation of either healthy or unhealthy adipose tissue and discuss key knowledge gaps that warrant future research.

Paternal Resistance Exercise Modulates Skeletal Muscle Remodeling Pathways in Fathers and Male Offspring Submitted to a High-Fat Diet

Although some studies have shown that a high-fat diet (HFD) adversely affects muscle extracellular matrix remodeling, the mechanisms involved in muscle trophism, inflammation, and adipogenesis have not been fully investigated. Thus, we investigated the effects of 8 weeks of paternal resistance training (RT) on gene and protein expression/activity of critical factors involved in muscle inflammation and remodeling of fathers and offspring (offspring exposed to standard chow or HFD). Animals were randomly distributed to constitute sedentary fathers (SF; n = 7; did not perform RT) or trained fathers (TF n = 7; performed RT), with offspring from mating with sedentary females. After birth, 28 male pups were divided into four groups (n = 7 per group): offspring from sedentary father submitted either to control diet (SFO-C) or high-fat diet (SFO-HF) and offspring from trained father submitted to control diet (TFO-C) or high-fat diet (TFO-HF). Our results show that an HFD downregulated collagen mRNA levels and upregulated inflammatory and atrophy pathways and adipogenic transcription factor mRNA levels in offspring gastrocnemius muscle. In contrast, paternal RT increased MMP-2 activity and decreased IL-6 levels in offspring exposed to a control diet. Paternal RT upregulated P70s6k and Ppara mRNA levels and downregulated Atrogin1 mRNA levels, while decreasing NFκ-B, IL-1β, and IL-8 protein levels in offspring exposed to an HFD. Paternal physical training influences key skeletal muscle remodeling pathways and inflammatory profiles relevant for muscle homeostasis maintenance in offspring submitted to different diets.

Strength training improves insulin resistance and differently affects mitochondria in skeletal muscle and visceral adipose tissue in high-fat fed mice

AIMS

Strength training (ST) improves insulin resistance and glucose tolerance by yet unknown mechanisms. The aims of this study were to investigate the effects of ST on mitochondrial adaptation in skeletal muscle and adipose tissue, on heat shock protein 72 (Hsp72) in skeletal muscle, and on visceral adipocyte size in mice with high-fat diet (HFD)-induced insulin resistance.

MATERIALS AND METHODS

Male Balb/c mice were divided into sedentary control-chow (C-chow), strength trained-chow (ST-chow), sedentary control-HFD (C-HFD) and strength trained-HFD (ST-HFD). Diet was provided for 12 weeks, while ladder climbing ST was performed for the final six weeks of the study at a frequency of three days per week.

KEY FINDINGS

Strength training led to increased strength, muscular endurance, and skeletal muscle hypertrophy. Compared to the C-HFD group, mice in the ST-HFD group decreased their whole-body insulin resistance, improved their glucose tolerance, and had higher activation of the insulin pathway in skeletal muscle. ST increased citrate synthase (CS) activity in skeletal muscle, but this increase was blunted in ST-HFD. Conversely, HFD reduced adipose tissue CS activity regardless of training status. Hsp72 content was reduced in C-HFD, but returned to control levels in ST-HFD. Finally, reduced epididymal adipocyte size was observed in ST-HFD.

SIGNIFICANCE

These results suggest that the improvement in insulin resistance induced by ST is related to mitochondrial adaptation in skeletal muscle, but not in adipose tissue. Moreover, this improvement might be related to increased skeletal muscle Hsp72 and reduced epididymal adipocyte size.

The Role of Oxidative Stress in Cardiovascular Aging and Cardiovascular Diseases

Aging can be seen as process characterized by accumulation of oxidative stress induced damage. Oxidative stress derives from different endogenous and exogenous processes, all of which ultimately lead to progressive loss in tissue and organ structure and functions. The oxidative stress theory of aging expresses itself in age-related diseases. Aging is in fact a primary risk factor for many diseases and in particular for cardiovascular diseases and its derived morbidity and mortality. Here we highlight the role of oxidative stress in age-related cardiovascular aging and diseases. We take into consideration the molecular mechanisms, the structural and functional alterations, and the diseases accompanied to the cardiovascular aging process.