Exercise training-driven exosomal miRNA-323-5p activity suppresses adipogenic conversion of 3T3-L1 cells via the DUSP3/ERK pathway.

Adipose-derived stem cell (ASC)-released exosomes (ASCexos) have multiple biological activities. We examined the effect of ASCexos derived from the inguinal adipose tissue of exercise-trained rats (EX-ASCexos) on adipogenic conversion of 3T3-L1 cells and analyzed their microRNA (miRNA) expression profiles. Differentiation of 3T3-L1 cells into adipocytes was performed for 9 d with EX-ASCexos or ASCexos from sedentary control rats (SED-ASCexos), and the expression of proteins and miRNA involved in adipogenic differentiation were determined.

High-intensity interval training enhances mRNA expression of IGF1Ea in rat Achilles tendon.

High-intensity interval training (HIIT) reportedly enhances the functional properties of the musculoskeletal system. However, the effects of HIIT on tendons remain unclear. Sixteen male rats were randomly assigned to the control (Con) or HIIT group (n = 8 in each group).

Impact of high-intensity interval training on tendon related gene expression in rat Achilles tendon.

Immobilization or aging associated with limited physical activity can lead to the functional deterioration of tendons, which has become an important public health concern. Therefore, growing research is focused on the effect of exercise training on preserving tendon function. Exercise training subjects muscles and tendons to repeated mechanical stress, and in vitro studies have revealed that repetitive mechanical loading stimulates tendon cell responses to changes in the extracellular matrix and functional properties of the tendon.

Tensile Loaded Tissue-Engineered Human Tendon Constructs Stimulate Myotube Formation.

Skeletal muscle possesses adaptability to mechanical loading and regenerative potential following muscle injury due to muscle stem cell activity. So far, it is known that muscle stem cell activity is supported by the roles of several interstitial cells within skeletal muscle in response to muscle damage. The adjacent tendon is also exposed to repetitive mechanical loading and possesses plasticity like skeletal muscle.

Human derived tendon cells contribute to myotube formation in vitro.

Skeletal muscle possesses remarkable adaptability to mechanical loading and regenerative potential following muscle injury primarily due to satellite cell activity. Although the roles of several types of interstitial cells in skeletal muscle have been documented, the signaling interplay between the skeletal muscle and the adjacent tendon tissue has not been elucidated. Here, we tested whether human tendon derived cells (tenocytes) could induce human myogenic cells (myoblasts) proliferation and differentiation in vitro using co-culture experiments that allowed us to investigate the effect of tenocytes secretion upon myogenic progression.

An Mechanical Damage Model of Isolated Myofibers in a Floating Culture Condition.

Muscle stem cells (satellite cells), located on the surface of myofibers, are rapidly activated from a quiescent state following skeletal muscle injury. Although satellite cell activation is an initial step in muscle regeneration, the stimulation of satellite cell activation by muscle injury remains to be elucidated. We recently established an mechanical damage model of myofibers, to analyze quiescent and activated satellite cells associated with myofibers isolated from the extensor digitorum longus muscle in mice.

Hoxa10 mediates positional memory to govern stem cell function in adult skeletal muscle.

Muscle stem cells (satellite cells) are distributed throughout the body and have heterogeneous properties among muscles. However, functional topographical genes in satellite cells of adult muscle remain unidentified. Here, we show that expression of Homeobox-A (Hox-A) cluster genes accompanied with DNA hypermethylation of the Hox-A locus was robustly maintained in both somite-derived muscles and their associated satellite cells in adult mice, which recapitulates their embryonic origin.

Myokine secretion following moderate-intensity endurance exercise under different environmental temperatures.

Purpose: In the present study, the effects of endurance exercise under different environmental temperatures on myokine responses were elucidated.

Methods: Seven healthy males (age: 22.7 ± 0.

Damaged Myofiber-Derived Metabolic Enzymes Act as Activators of Muscle Satellite Cells.

Muscle satellite cells are normally quiescent but are rapidly activated following muscle damage. Here, we investigated whether damaged myofibers influence the activation of satellite cells. Our findings revealed that satellite cells are directly activated by damaged-myofiber-derived factors (DMDFs).

The body region specificity in murine models of muscle regeneration and atrophy.

Aim: Skeletal muscles are distributed throughout the body, presenting a variety of sizes, shapes and functions. Here, we examined whether muscle regeneration and atrophy occurred homogeneously throughout the body in mouse models.

Methods: Acute muscle regeneration was induced by a single intramuscular injection of cardiotoxin in adult mice.

Irisin response to downhill running exercise in humans.

Purpose: To determine the effects of exercise-induced muscle damage, we examined irisin responses during level running (LR), with less muscle damage, and downhill running (DHR), with greater muscle damage under equivalent exercise duration and oxygen consumption (⩒O2) conditions.

Methods: Fifteen healthy men (age: 21.6 ± 2.

Notch1 and Notch2 Coordinately Regulate Stem Cell Function in the Quiescent and Activated States of Muscle Satellite Cells.

Satellite cells, the muscle tissue stem cells, express three Notch receptors (Notch1-3). The function of Notch1 and Notch2 in satellite cells has to date not been fully evaluated. We investigated the role of Notch1 and Notch2 in myogenic progression in adult skeletal muscle using tamoxifen-inducible satellite cell-specific conditional knockout mice for Notch1 (N1-scKO), Notch2 (N2-scKO), and Notch1/Notch2 (scDKO).

Effect of sprint training on resting serum irisin concentration - Sprint training once daily vs. twice every other day.

Objective: Exercise twice every other day has been shown to lead to increasing peroxisome proliferator receptor γ coactivator-1α (PGC-1α) expression (up-stream factor of irisin) via lowered muscle glycogen level during second of exercise compared with exercise once daily. This study determined the influence of 4weeks of sprint training (training once daily vs. twice every other day) on the serum irisin concentration.

Resistance exercise induces a greater irisin response than endurance exercise.

Objective: We determined detailed time-course changes in the irisin response to acute exercise using different exercise modes.

Methods: In experiment 1, seven healthy males rested for 12h (8:00-20:00) to determine the diurnal variation in plasma irisin concentration. In experiment 2, 10 healthy males conducted three exercises to clarify time-course changes in plasma irisin concentration over 6h, using a randomized crossover design.

Influences of increased training volume on exercise performance, physiological and psychological parameters.

Background: The aim of this study was to investigate the influence of excessive training on exercise performance and physiological and psychological parameters.

Methods: Eight physically active males (age, mean±standard deviation [SD]: 23±3 years) completed 3 weeks of an intervention program consisting of normal (N), intensified (IT), and recovery (R) training phases (7 days for each phase). Physiological and psychological parameters were measured at rest before the intervention (Pre), and every Monday, Wednesday, and Saturday (day 1, day 3, day 6, respectively), and exercise performance tests were performed before the intervention (Pre) and every Saturday (day 6) during the intervention period.

The influence of environmental temperature on appetite-related hormonal responses.

Background: Acute exercise in the heat has been shown to reduce appetite. However, the influence of exercise in the cold on appetite regulation remains unclear. The aim of this study was to compare exercise-induced appetite regulation under three different environmental temperatures.

High-intensity exercise causes greater irisin response compared with low-intensity exercise under similar energy consumption.

Irisin is mainly released from skeletal muscle (myocytes) and promotes thermogenesis by browning of the white adipose tissue. Although exercise has been shown to increase irisin concentration in blood and myocytes via up-regulation peroxisome proliferator receptor γ coactivator-1α (PGC-1α) expression, the influence of exercise intensity on irisin secretion remains unclear. Therefore, we determined circulating irisin responses following a single bout of running at different intensities.