The Effects of Exercise on White and Brown Adipose Tissue Cellularity, Metabolic Activity and Remodeling

HDL-Cholesterol and Triglycerides Dynamics: Essential Players in Metabolic Syndrome

Metabolic syndrome (MetS) is a complex cluster of interrelated metabolic disorders that significantly elevate the risk of cardiovascular disease, making it a pressing public health concern worldwide. Among the key features of MetS, dyslipidemia-characterized by altered levels of high-density lipoprotein cholesterol (HDL-C) and triglycerides (TG)-plays a crucial role in the disorder's progression. This review aims to elucidate the intricate interplay between HDL-C and TG within the context of lipid metabolism and cardiovascular health, while also addressing the detrimental impact of various cardiovascular risk factors and associated comorbidities. The dynamics of HDL-C and TG are explored, highlighting their reciprocal relationship and respective contributions to the pathophysiology of MetS. Elevated levels of TGs are consistently associated with reduced concentrations of HDL-C, resulting in a lipid profile that promotes the development of vascular disease. Specifically, as TG levels rise, the protective cardiovascular effects of HDL-C are diminished, leading to the increased accumulation of pro-atherogenic TG-rich lipoproteins and low-density lipoprotein particles within the vascular wall, contributing to the progression of atheromas, which can ultimately result in significant ischemic cardiovascular events. Ultimately, this paper underscores the significance of HDL and TG as essential targets for therapeutic intervention, emphasizing their potential in effectively managing MetS and reducing cardiovascular risk.

Serum Proteomic and Metabolomic Signatures of High Versus Low Physical Function in Octogenarians

Physical function declines with aging, yet there is considerable heterogeneity, with some individuals declining very slowly while others experience accelerated functional decline. To gain insight into mechanisms promoting high physical function with aging, we performed proteomics, targeted metabolomics, and targeted kynurenine-focused metabolomic analyses on serum specimens from three groups of octogenarians: High-functioning master athletes (HF, n = 16), healthy normal-functioning non-athletes (NF, n = 12), and lower functioning non-athletes (LF, n = 11). Higher performance status was associated with evidence consistent with: Lower levels of circulating proinflammatory markers, as well as unperturbed tryptophan metabolism, with the normal function of the kynurenic pathway; higher circulating levels of lysophosphatidylcholines that have been previously associated with better mitochondrial oxidative capacity; lower activity of the integrated stress response; lower levels of circulating SASP protein members; and lower levels of proteins that reflect neurodegeneration/denervation. Extending the observations of previous studies focused on the biomarkers of aging that predict poor function, our findings show that many of the same biomarkers associated with poor function exhibit attenuated changes in those who maintain a high function. Because of the cross-sectional nature of this study, results should be interpreted with caution, and bidirectional causality, where physical activity behavior is both a cause and outcome of differences in the biomarker changes, remains a possible interpretation.

Endurance Exercise Training Alters Lipidomic Profiles of Plasma and Eight Tissues in Rats: a MoTrPAC study

Endurance exercise training (ExT) induces metabolic, structural, and functional adaptations via lipidomic modifications, yet the systematic elucidation of lipidome alterations in response to ExT remains incomplete. As a part of the Molecular Transducers of Physical Activity Consortium (MoTrPAC), we leveraged non-targeted and targeted lipidomics for the systematic discovery of lipid alterations in the brown adipose tissue, heart, hippocampus, kidney, liver, lung, skeletal muscle gastrocnemius, subcutaneous white adipose tissue, and plasma in response to 1, 2, 4 or 8 weeks of ExT in 6-month-old male and female Fischer-344 rats. This study demonstrates that these tissues, each with distinct lipidomic features, underwent dynamic, sexually dimorphic lipid remodeling. Exercise trained animals showed reduced whole-body adiposity and improved cardiorespiratory fitness, along with enhanced utilization of lipid stores and dynamic triacylglycerol remodeling compared to sedentary controls in all tissues except hippocampus. They also showed modifications in phospholipids, lysophospholipids, oxylipins, and ceramides in several tissues. Coordinated changes across tissues reflect systemic tissue communication, with liver-plasma-heart connection potentially playing a key role in systemic lipid metabolism during ExT. These data will improve our understanding of lipid-associated biological processes underlying the health-promoting benefits of ExT.

Reverse epidemiology of obesity paradox: Fact or fiction?

Obesity paradox refers to the clinical observation that when acute cardiovascular decompensation occurs, patients with obesity may have a survival benefit. This apparently runs counter to the epidemiology of obesity, which may increase the risk for non-communicable diseases (NCDs). The scientific community is split on obesity paradox, with some supporting it, while others call it BMI paradox. This review: (a) defines the obesity paradox, and its proposed role in overall mortality in NCDs; (b) delineates evidence for and against obesity paradox; (c) presents the importance of using different indices of body mass to assess the risk in NCDs; (d) examines the role of metabolically healthy obesity in obesity paradox, and emerging importance of cardio-respiratory fitness (CRF) as an independent predictor of CVD risk and all-cause mortality in patients with/without obesity. Evidence suggests that the development of obesity and insulin resistance are influenced by genetic (or ethnic) make up and dietary habits (culture) of the individuals. Hence, this review presents lean diabetes, which has higher total CVD and non-CVD mortality as compared to diabetics with obesity and the possibility of maternal factors programming cardiometabolic risk during fetal development, which may lead to a paradigm shift in our understanding of obesity.

Swimming in cold water increases the browning process by diminishing the Myostatin pathway

BACKGROUND

Brown adipose tissue (BAT) is a thermogenic tissue that uncouples oxidative phosphorylation from ATP synthesis and increases energy expenditure via non-shivering thermogenesis in mammals. Cold exposure and exercise have been shown to increase BAT and browning of white adipose tissue (WAT) in mice. This study aimed to determine whether there is an additive effect of exercise during cold exposure on markers related to browning of adipose tissue. in Wistar rats.

METHODS

Twenty-four male Wistar rats were randomly divided into three groups: Control (C, 25˚C), Swimming in Neutral (SN, 30˚C) water, and Swimming in Cold (SC, 15˚C) water. Swimming included intervals of 2-3 min, 1 min rest, until exhausted, three days a week for six weeks, with a training load of 3-6% body weight. After the experimental protocol, interscapular BAT and inguinal subcutaneous white adipose tissue (WAT) were excised, weighed, and processed for beiging marker gene expression.

RESULTS

SN and SC resulted in lower body weight gain, associated with reduced WAT and BAT volume and increased BAT number with greater effects observed in SC. Myostatin protein expression was lower in BAT, WAT, soleus muscle, and serum NC and SC compared to the C group. Expression of the interferon regulatory factor-4 (IRF4) gene in both BAT and WAT tissues was significantly greater in the SC than in the C. Expression of the PGC-1α in BAT was significantly increased in the SC compared to C and increased in WAT in NC and SC. Expression of the UCP1 in BAT and WAT increased in the SC group compared to other groups.

CONCLUSION

The findings demonstrate that six weeks of swimming training in cold water promotes additive effects of the expression of genes and proteins involved in the browning process of adipose tissue in Wistar rats. Myostatin inhibition may possess a regulator effect on the PGC-1α - UCP1 pathway that mediates adipose tissue browning.

The characterization of metabolic changes in adipose tissues and muscles due to different exercise intensities by Dixon in healthy young men

PURPOSE

To delineate the alterations in adipose and muscle tissue composition and functionality among healthy young men across varying exercise intensities, which help to elucidate the impact of exercise intensity on weight management and inform fitness planning.

METHOD

3D Dixon MRI scans were performed on the neck and supraclavicular area in 10 high-intensity exercises (HIE) athletes, 20 moderate intensity exercises (MIE) athletes and 19 low-intensity exercises non-athlete male controls (NCM). Twelve imaging parameters, including the total volume of muscle, white adipose tissue (WAT), brown adipose tissue (BAT), and the mean fat-water fraction (FWF) within these tissues. Additionally, ratios of BAT or WAT to total fat (BATr or WATr) and the proportions of muscle, BAT, or WAT to total tissue volume (Musp, BATp, and WATp) were calculated. Parameters were compared across groups and correlated with Body Mass Index (BMI), waistline, and hipline.

RESULTS

The HIE group exhibited the highest total muscle (totalMUS) and brown adipose tissue (totalBAT) volumes among the three groups. Conversely, the NCM group had significantly higher fwfFAT and fwfBAT values. The MUSp was higher in the HIE and MIE groups compared to NCM, while the BATp and WATp were lower. Furthermore, the BATr in HIE and MIE groups were higher than NCM group while the WATr were lower. Significant linear relationships were observed between totalBAT, totalWAT, MUSp, BATr, fwfFAT, and BMI, waistline (P < 0.05) across all groups.

CONCLUSIONS

MIE is sufficient for the purpose of weight control, While HIE helps to further increase the muscle mass. All three physical indexes were significantly associated with the image parameters, with waistline emerging as the most effective indicator for detecting metabolic changes across all groups.

Changes in the Expression of Inflammatory Genes Induced by Chronic Exercise in the Adipose Tissue: Differences by Sex

The impact of obesity on adipose tissue function is well acknowledged, but the role of physical exercise in regulating inflammatory markers and gene expression in obese individuals remains uncertain. This study aims to investigate the effects of chronic exercise on inflammatory gene expression in adipose tissue and to explore sex differences in response to exercise. The study involved 29 obese participants (13 men, 16 women) aged 38 to 54 years with a mean BMI of 36.05 ± 4.99 kg/m2. Participants underwent an 8-week concurrent training program comprising three weekly sessions of ~60 min each. The sessions included joint mobility exercises, cardiovascular activation, and cardiorespiratory resistance exercises at medium to low intensity. A fine-needle aspiration biopsy of abdominal subcutaneous adipose tissue was performed for gene expression analysis using quantitative polymerase chain reaction (qPCR). The study demonstrated that chronic exercise modulates the expression of pro-inflammatory genes in subcutaneous adipose tissue, particularly ADIPOR2 (p = 0.028), leptin (p = 0.041), and IFNg (p = 0.040) (downregulated). Interestingly, regardless of sex, the exercise programs had an independent effect on pro-inflammatory genes. Overall, this study provides insight into the role of chronic exercise in modulating adipose tissue gene expression in obese individuals. Further research involving both sexes is recommended to tailor exercise interventions for better outcomes.

Molecular adaptations in response to exercise training are associated with tissue-specific transcriptomic and epigenomic signatures

Regular exercise has many physical and brain health benefits, yet the molecular mechanisms mediating exercise effects across tissues remain poorly understood. Here we analyzed 400 high-quality DNA methylation, ATAC-seq, and RNA-seq datasets from eight tissues from control and endurance exercise-trained (EET) rats. Integration of baseline datasets mapped the gene location dependence of epigenetic control features and identified differing regulatory landscapes in each tissue. The transcriptional responses to 8 weeks of EET showed little overlap across tissues and predominantly comprised tissue-type enriched genes. We identified sex differences in the transcriptomic and epigenomic changes induced by EET. However, the sex-biased gene responses were linked to shared signaling pathways. We found that many G protein-coupled receptor-encoding genes are regulated by EET, suggesting a role for these receptors in mediating the molecular adaptations to training across tissues. Our findings provide new insights into the mechanisms underlying EET-induced health benefits across organs.

Effects of aerobic, resistance, and high-intensity interval training on thermogenic gene expression in white adipose tissue in high fat diet induced obese mice

OBJECTIVE

Global prevalence of obesity has continued to rise and poses public health concerns. Current anti-obesity medications are mainly focused on suppressing appetite. Thermogenic fat cells that increase energy expenditure may be a promising alternative target to combat obesity. Our study aims to investigate the effects of aerobic, resistance, and high-intensity interval training on thermogenic gene expression in white adipose tissue in high fat diet induced obese mice.

METHODS

Fifty 6-week-old male C57BL/6 mice were initially divided into control group and high fat diet group for obesity induction. After 8 weeks of obesity induction, obese mice were subdivided into sedentary, aerobic exercise, resistance exercise, and high intensity interval training groups. Trained obese mice were submitted to 8 weeks of exercise.

RESULTS

Our results showed that all three exercises significantly decreased body weight, and improved metabolic profiles including glucose tolerance, total cholesterol, and low-density lipoprotein cholesterol. Moreover, aerobic exercise training increases serum irisin levels and thermogenic gene expressions such as Prdm16, Cidea, and Pgc-1α in epididymal white adipose tissue of obese mice.

CONCLUSION

Our findings suggest that when it comes to the adaption of thermogenic fat cells, the modality of exercise should be taken into consideration. Aerobic exercise may induce a modest increase in the expression levels of certain thermogenic genes in epididymal white adipose tissue.

Effects of combined aerobic exercise and diet on cardiometabolic health in patients with obesity and type 2 diabetes: a systematic review and meta-analysis

BACKGROUND

Lifestyle modifications involving diet and exercise are recommended for patients diagnosed with obesity and type 2 diabetes mellitus (T2DM). The purpose of this review was to systematically evaluate the effects of combined aerobic exercise and diet (AEDT) on various cardiometabolic health-related indicators among individuals with obesity and T2DM.

METHODOLOGY

A comprehensive search of the PubMed/Medline, Web of Science, Scopus, Science Direct, Cochrane, and Google Scholar databases was conducted for this meta-analysis. The Cochrane risk of bias tool was used to evaluate eligible studies, and the GRADE tool was used to rate the certainty of evidence. A random-effects model for continuous variables was used, and the results were presented as mean differences or standardised mean differences with 95% confidence intervals.

RESULTS

A total of 16,129 studies were retrieved; 20 studies were included, and data were extracted from 1,192 participants. The findings revealed significant improvements in body mass index, body weight, waist circumference, systolic blood pressure, diastolic blood pressure, total cholesterol, triglycerides, fasting blood glucose, fasting plasma insulin, glycated hemoglobin, leptin, interleukin-6, C-reactive protein, and adiponectin (p < 0.05) compared to the standard treatment (ST) group. No significant differences were observed between the AEDT and ST groups in fat mass, hip circumference, waist-to-hip ratio, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, and tumor necrosis factor-alpha. The present findings are based on low- to moderate-quality evidence.

CONCLUSIONS

AEDT may be a critical behavior for holistic cardiometabolic health-related benefits as a contemporary anti-obesity medication due to its significant positive impact on patients with obesity and T2DM. Nevertheless, further robust evidence is necessary to determine whether AEDT is an effective intervention for lowering cardiovascular and metabolic risk factors among individuals with obesity and T2DM.

Physical activity and batokines

Brown and beige adipose tissue share similar functionality, being both tissues specialized in producing heat through nonshivering thermogenesis and also playing endocrine roles through the release of their secretion factors called batokines. This review elucidates the influence of physical exercise, and myokines released in response, on the regulation of thermogenic and secretory functions of these adipose tissues and discusses the similarity of batokines actions with physical exercise in the remodeling of adipose tissue. This adipose tissue remodeling promoted by autocrine and paracrine batokines or physical exercise seems to optimize its functionality associated with better health outcomes.

TMT Labeling Reveals the Effects of Exercises on the Proteomic Characteristics of the Subcutaneous Adipose Tissue of Growing High-Fat-Diet-Fed Rats

Aim: Growing period is an important period for fat remodeling. High-fat diet and exercise are reasons for adipose tissue (AT) remodeling, but existing evidence is not enough. Therefore, the effects of moderate-intensity continuous training (MICT) and high-intensity interval training (HIIT) on the proteomic characteristics of the subcutaneous AT of growing rats on normal diet or high-fat diet (HFD) were determined. Methods: Four-week-old male Sprague-Dawley rats (n = 48) were subdivided into six groups: normal diet control group, normal diet-MICT group, normal diet-HIIT group, HFD control group, HFD-MICT group, and HFD-HIIT group. Rats in the training group ran on a treadmill 5 days a week for 8 weeks (MICT: 50 min at 60-70% VO_2max intensity; HIIT: 7 min of warm-up and recovery at 70% VO_2max intensity, 6 sets of 3 min of 30% VO_2max followed by 3 min 90% VO_2max). Following physical assessment, inguinal subcutaneous adipose tissue (sWAT) was collected for proteome analysis using tandem mass tag labeling. Results: MICT and HIIT attenuated body fat mass and lean body mass but did not affect weight gain. Proteomics revealed the impact of exercise on ribosome, spliceosome, and the pentose phosphate pathway. However, the effect was reversed on HFD and normal diet. The differentially expressed proteins (DEPs) affected by MICT were related to oxygen transport, ribosome, and spliceosome. In comparison, the DEPs affected by HIIT were related to oxygen transport, mitochondrial electron transport, and mitochondrion protein. In HFD, HIIT was more likely to cause changes in immune proteins than MICT. However, exercise did not seem to reverse the protein effects of HFD. Conclusion: The exercise stress response in the growing period was stronger but increased the energy metabolism and metabolism. MICT and HIIT can reduce fat, increase muscle percentage, and improve maximum oxygen uptake in rats fed with HFD. However, in rats with normal diet, MICT and HIIT triggered more immune responses of sWAT, especially HIIT. In addition, spliceosomes may be the key factors in AT remodeling triggered by exercise and diet.

Exercise-Induced Adipose Tissue Thermogenesis and Browning: How to Explain the Conflicting Findings?

Brown adipose tissue (BAT) has been widely studied in targeting against metabolic diseases such as obesity, type 2 diabetes and insulin resistance due to its role in nutrient metabolism and energy regulation. Whether exercise promotes adipose tissue thermogenesis and browning remains controversial. The results from human and rodent studies contradict each other. In our opinion, fat thermogenesis or browning promoted by exercise should not be a biomarker of health benefits, but an adaptation under the stress between body temperature regulation and energy supply and expenditure of multiple organs. In this review, we discuss some factors that may contribute to conflicting experimental results, such as different thermoneutral zones, gender, training experience and the heterogeneity of fat depots. In addition, we explain that a redox state in cells potentially causes thermogenesis heterogeneity and different oxidation states of UCP1, which has led to the discrepancies noted in previous studies. We describe a network by which exercise orchestrates the browning and thermogenesis of adipose tissue with total energy expenditure through multiple organs (muscle, brain, liver and adipose tissue) and multiple pathways (nerve, endocrine and metabolic products), providing a possible interpretation for the conflicting findings.