Eccentric resistance training and β-hydroxy-β-methylbutyrate free acid affects muscle PGC-1α expression and serum irisin, nesfatin-1 and resistin in rats

Interaction between Selected Adipokines and Musculoskeletal and Cardiovascular Systems: A Review of Current Knowledge

Adipokines are substances secreted by adipose tissue that are receiving increasing attention. The approach to adipose tissue has changed in recent years, and it is no longer looked at as just a storage organ but its secretion and how it influences systems in the human body are also looked at. The role of adipokine seems crucial in developing future therapies for pathologies of selected systems. In this study, we look at selected adipokines, leptin, adiponectin, chemerin, resistin, omentin-1, nesfatin, irisin-1, visfatin, apelin, vaspin, heparin-binding EGF-like growth factor (HB-EGF), and TGF-β2, and how they affect systems in the human body related to physical activity such as the musculoskeletal and cardiovascular systems.

Effects of physical activity and exercise on Nucleobindin-2 gene expression and Nesfatin-1 concentration: A rapid review

The aim of this rapid review is to examine the research evidence that presents the effects of physical activity and exercise on Nucleobindin-2 (NUCB2) gene expression and Nesfatin-1 concentration. Five databases (PubMed, Science Direct, Springer, Wiley, and Google Scholar) were searched for eligible studies from the earliest available date to August 2023. In human studies, Nesfatin-1 concentration either remains unchanged or increases after exercise training. It appears that higher exercise intensity and longer duration of training accentuate the increase of blood Nesfatin-1 concentration. The few human studies that have examined the acute response of exercise on Nesfatin-1 concentration from blood draws show conflicting results. There is a severe lack of biopsy studies in humans which warrants attention. All published animal studies have used the mouse model. The majority show that regular exercise training increases tissue NUCB2/Nesfatin-1. In some animal studies, where the effects of exercise on tissue Nesfatin-1 concentration has been seen as significant, there has been no significant effect of exercise on plasma Nesfatin-1 concentration. All animal studies evaluated the effect of endurance training except one which used resistance training. No animal studies have investigated the effects of acute exercise, which warrants investigation. In conclusion, human and animal studies have shown that physical training can increase NUCB2/Nesfatin-1, but research evidence examining the effect of acute exercise is in its infancy. In addition, future comparative studies are needed to compare the effects of different training protocols on NUCB2/Nesfatin-1 in humans and animals.

Effect of Eccentric Exercise on Metabolic Health in Diabetes and Obesity

There is a growing body of evidence showing the importance of physical activity against civilization-induced metabolic diseases, including type 2 diabetes (T2DM) and obesity. Eccentric contraction, when skeletal muscles generate force by lengthening, is a unique type of skeletal muscle activity. Eccentric contraction may lead to better power production characteristics of the muscle because eccentric contraction requires less energy and can result in higher tension. Therefore, it is an ideal tool in the rehabilitation program of patients. However, the complex metabolic effect (i.e., fat mass reduction, increased lipid oxidation, improvement in blood lipid profile, and increased insulin sensitivity) of the eccentric contraction alone has scarcely been investigated. This paper aims to review the current literature to provide information on whether eccentric contraction can influence metabolic health and body composition in T2DM or obesity. We also discussed the potential role of myokines in mediating the effects of eccentric exercise. A better understanding of the mechanism of eccentric training and particularly their participation in the regulation of metabolic diseases may widen their possible therapeutic use and, thereby, may support the fight against the leading global risks for mortality in the world.

Mechanical Stimulation Protects Against Chondrocyte Pyroptosis Through Irisin-Induced Suppression of PI3K/Akt/NF-κB Signal Pathway in Osteoarthritis

Irisin, a myokine secreted by muscle during physical exercise, is known to have biological activities in different cell types. Chondrocyte inflammation and pyroptosis have been shown to play important roles in osteoarthritis (OA). In this study, we investigated the effects of exercise-induced irisin during different intensities of treadmill exercise in a rat OA model and the anti-inflammatory and antipyroptosis mechanism of irisin in OA chondrocytes. Forty-eight SD rats (n = 8) were randomly assigned to control (CG), OA (OAG), OA groups under different intensities of treadmill exercise (OAL, OAM, and OAH), OAM + irisin neutralizing antibodies group (OAM + irisin (NA)). The levels of irisin and the severity of OA between groups were detected using ELISA, histology, immunohistochemistry, X-ray and computed tomography and magnetic resonance imaging. The anti-inflammatory and antipyroptosis mechanisms of irisin were investigated in vitro in OA chondrocytes preincubated with recombinant irisin (0, 5, or 10 ng/ml) for 1 h before treatment with interleukin-1β (IL-1β) for 24 h mRNA and protein expression levels were determined using quantitative reverse transcription polymerase chain reaction, and western blot analyses. Morphological changes and cell death associated with pyroptosis were examined using transmission electron microscopy, flow cytometry and immunofluorescence. Moderate-intensity treadmill exercise increased the levels of irisin, exhibiting the best therapeutic effects on OA which could be suppressed by irisin neutralizing antibodies. Irisin not only recovered the expression of collagen II and attenuated that of MMP-13 and ADAMTS-5 in IL-1β-induced OA chondrocytes by inhibiting the PI3K/Akt/NF-κB signaling pathway, but also inhibited the activity of nod-like receptor protein-3 (NLRP3)/caspase-1, thus ameliorating pyroptosis in chondrocytes. In conclusion, moderate mechanical stimulation protects against chondrocyte pyroptosis through irisin-induced suppression of PI3K/Akt/NF-κB signal pathway in osteoarthritis.

The Physiological Role of Irisin in the Regulation of Muscle Glucose Homeostasis

Irisin is a myokine that primarily targets adipose tissue, where it increases energy expenditure and contributes to the beneficial effects of exercise through the browning of white adipose tissue. As our knowledge has deepened in recent years, muscle has been found to be a major target organ for irisin as well. Several studies have attempted to characterize the role of irisin in muscle to improve glucose metabolism through mechanisms such as reducing insulin resistance. Although they are very intriguing reports, some contradictory results make it difficult to grasp the whole picture of the action of irisin on muscle. In this review, we attempted to organize the current knowledge of the role of irisin in muscle glucose metabolism. We discussed the direct effects of irisin on glucose metabolism in three types of muscle, that is, skeletal muscle, smooth muscle, and the myocardium. We also describe irisin’s effects on mitochondria and its interactions with other hormones. Furthermore, to consider the relationship between the irisin-induced improvement of glucose metabolism in muscle and systemic disorders of glucose metabolism, we reviewed the results from animal interventional studies and human clinical studies.

Effects of high-intensity interval training and flaxseed oil supplement on learning, memory and immobility: relationship with BDNF and TrkB genes

This study examined the independent and combined effects of high-intensity interval training (HIIT) and flaxseed oil supplementation on cognitive/executive functions in middle-aged rats. Hippocampal neurotropic brain factor (BDNF) and tyrosine kinase receptor B (TrkB) gene expression were also measured. Animals were randomly divided into groups including no exercise control and saline (CS), no exercise control and flaxseed oil supplement (CF), exercise training-and saline (TS) and exercise training and flaxseed oil supplement (TF). The training groups undertook a program of HIIT (10 weeks, five sessions per week) and the supplement groups received flaxseed oil supplement (300 mg/kg). The results showed that HIIT and flaxseed oil supplementation independently had positive effects on memory and learning (P<0.05). HIIT and flaxseed oil independently decreased immobility behaviour and increased hippocampal BDNF and TrkB genes expression (P<0.05). HIIT and flaxseed oil combination had a greater effect on some variables (hippocampal TrkB gene expression, memory and immobility) compared to each intervention alone (P<0.05). In conclusion, HIIT and flaxseed oil can independently improve cognitive/executive functions. In addition, HIIT had a greater positive effect than flaxseed oil supplementation on memory and immobility. The combination of HIIT and flaxseed oil supplement had a more positive effect compared to each intervention alone on memory, and immobility. Hippocampal BDNF gene expression did not significantly differ in the combination or independent groups. Thus, future work is needed on several other genes in different segments of the brain to find the additive-mechanisms involved in memory and immobility regulation and younger and older species of rat should be examined.

Effects of 2-week HMB-FA supplementation with or without eccentric resistance exercise on expression of some genes related to muscle protein turnover and serum irisin and IGF-1 concentrations

Protein turnover is a process that is regulated by several factors and can lead to muscle hypertrophy or atrophy. The purpose of the present study was to determine the effects of β-hydroxy-β-methylbutyrate free acid (HMB-FA) and eccentric resistance exercise on variables related to protein turnover in rats. Thirty-two male rats were randomly assigned into four groups of eight, including control, control-HMB, exercise, and exercise-HMB. Animals in HMB groups received 340 mg/kg/day for two weeks. Animals in the exercise groups performed one session of eccentric resistance exercise consisting of eight repetitions descending from a ladder with a slope of 80 degree, with an extra load of two times body weight (100% 1RM). Twenty-four hours after the exercise session, triceps brachii muscle and serum were collected for further analysis. Exercise and HMB-FA induced lower muscle myostatin and higher muscle Fibronectin type III domain containing 5 (FNDC5), P70-S6 kinase 1 gene expression, as well as higher serum irisin and IGF-1 concentrations. Exercise alone induced higher caspase-3 and caspase-8 gene expression while HMB-FA alone induced lower caspase 3 gene expression. HMB-FA supplement increased the effect of exercise on muscle FNDC5, myostatin, and P70-S6 kinase 1 gene expression. The interaction of exercise and HMBFA resulted in an additive effect, increasing serum irisin and IGF-1 concentrations. In conclusion, a 2-week HMB-FA supplementation paired with acute eccentric resistance exercise can positively affect some genes related to muscle protein turnover.

β-hydroxy-β-methylbutyrate supplementation benefits the effects of resistance training on body fat reduction via increased irisin expression in white adipose tissue

The effects of resistance training (RT) associated with calcium β-hydroxyβ-methylbutyrate (CaHMB) supplementation on the body composition and gene expression of cytokines related to skeletal muscle hypertrophy and adipose tissue metabolism were studied in rats. Male Wistar rats were divided into four groups of 12 animals: sedentary control (SC); sedentary supplemented (SS); resistance training control (RTC) and resistance training supplemented (RTS). Rats from RTC and RTS groups were submitted to an RT programme and those from SS and RTS groups received 1 mL of CaHMB (320 mg kg^-1 day^-1) by gavage, for 8 weeks. We evaluated: body composition; plasma lipid profile; the gene expression of interleukin (IL)-6, IL-10, IL-15 and fibronectin type III domain-containing protein 5 (FNDC-5) in skeletal muscle, and IL-6, mitochondrial uncoupling protein 1 (UCP-1) in white adipose tissue (WAT); and the concentration of irisin in WAT. Compared to RTC alone, the combination of CaHMB with RT (RTS) further reduced abdominal circumference (5.3%), Lee index (2.4%), fat percentage (24.4%), plasma VLDL cholesterol (16.8%) and triglycerides (17%) and increased the gene expression of FNDC-5 (78.9%) and IL-6 (47.4%) in skeletal muscle and irisin concentration (26.9%) in WAT. Neither RT nor CaHMB affected the protein percentage or the gene expression of IL-6 and UCP-1 in WAT and IL-10, IL-15 in skeletal muscle. In conclusion, CaHMB supplementation increased the beneficial effects of RT on body fat reduction and was associated with muscular genic expression of IL-6 and FNDC-5 and irisin concentration in WAT, despite the lack of change in protein mass and maximal strength.