• Journal of the Korea Society of Computer and Information
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• v.24 no.9
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• pp.97-102
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• 2019

Several studies have recently demonstrated that skeletal muscle is an endocrine organ releasing and expressing myokines acting in an endocrine or paracrine manner. Irisin is a hormene-like myokine induced after physical exercise by muscle fibers. It was primarily recognized as a molecule able to advance the "browning response" in white adipose tissue, however, it has been recetly identified that irisin also has a fundamental role in the control of bone mass. We study evidence for its possible skeletal effects, including the fundamental role that irisin is involved in the control of bone mass, with beneficial effects on geometry and cortical mineral density. As loss of muscle mass and bone density occurs with immobility, metabolic disease and aging, future studies researching the efficacy of irisin in reversing muscle wasting and restoring bone would be important to proving irisin as a molecule that combines helpful effects for treating muscular atrophy and osteoporosis in elderly people.

• BMB Reports
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• v.51 no.1
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• pp.39-44
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• 2018

Exchange protein directly activated by cAMP (Epac) 2a-knockout (KO) mice exhibit accelerated diet-induced obesity and are resistant to leptin-mediated adipostatic signaling from the hypothalamus to adipose tissue, with sustained food intake. However, the impact of Epac2a deficiency on hypothalamic regulation of sympathetic nervous activity (SNA) has not been elucidated. This study was performed to elucidate the response of Epac2a-KO mice to dexamethasone-induced muscle atrophy and acute cold stress. Compared to age-matched wild-type mice, Epac2a-KO mice showed higher energy expenditures and expression of myogenin and uncoupling protein-1 in skeletal muscle (SM) and brown adipose tissue (BAT), respectively. Epac2a-KO mice exhibited greater endurance to dexamethasone and cold stress. In wild-type mice, exogenous leptin mimicked the responses observed in Epac2a-KO mice. This suggests that leptin-mediated hypothalamic signaling toward SNA appears to be intact in these mice. Hence, the potentiated responses of SM and BAT may be due to their high plasma leptin levels.

• Journal of Ginseng Research
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• v.43 no.3
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• pp.475-481
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• 2019

Background: The ginsenoside Rg1 has been shown to exert various pharmacological activities with health benefits. Previously, we have reported that Rg1 promoted myogenic differentiation and myotube growth in C2C12 myoblasts. In this study, the in vivo effect of Rg1 on fiber-type composition and oxidative metabolism in skeletal muscle was examined. Methods: To examine the effect of Rg1 on skeletal muscle, 3-month-old mice were treated with Rg1 for 5 weeks. To assess muscle strength, grip strength tests were performed, and the lower hind limb muscles were harvested, followed by various detailed analysis, such as histological staining, immunoblotting, immunostaining, and real-time quantitative reverse transcription polymerase chain reaction. In addition, to verify the in vivo data, primary myoblasts isolated from mice were treated with Rg1, and the Rg1 effect on myotube growth was examined by immunoblotting and immunostaining analysis. Results: Rg1 treatment increased the expression of myosin heavy chain isoforms characteristic for both oxidative and glycolytic muscle fibers; increased myofiber sizes were accompanied by enhanced muscle strength. Rg1 treatment also enhanced oxidative muscle metabolism with elevated oxidative phosphorylation proteins. Furthermore, Rg1-treated muscles exhibited increased levels of anabolic S6 kinase signaling. Conclusion: Rg1 improves muscle functionality via enhancing muscle gene expression and oxidative muscle metabolism in mice.

• Journal of Ginseng Research
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• v.46 no.5
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• pp.657-665
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• 2022

Background: Sarcopenia is a new and emerging risk factor aggravating the quality of life of elderly population. Because Korean Red Ginseng (RG) is known to have a great effect on relieving fatigue and enhancing physical performance, it is invaluable to examine its potential as an anti-sarcopenic drug. Methods: Anti-sarcopenic effect of non-saponin fraction of Korean Red Ginseng (RGNS) was evaluated in C2C12 myoblasts treated with C2-ceramide to induce senescence phenotypes, and 22-month-old mice fed with chow diet containing 2% RGNS (w/w) for 4 further months. Results: The RGNS treatment significantly alleviated cellular senescence indicated by intracellular lipid accumulation, increased amount of lysosomal β-galactosidase, and reduced proliferative capacity in C2C12 myoblasts. This effect was not observed with saponin fraction. In an aged mouse, the 4-month-RGNS diet significantly improved aging-associated loss of muscle mass and strength, assessed by the weights of hindlimb skeletal muscles such as tibialis anterior (TA), extensor digitorum longus (EDL), gastrocnemius (GN) and soleus (SOL), and the cross-sectional area (CSA) of SOL muscle, and the behaviors in grip strength and hanging wire tests, respectively. During the same period, an aging-associated shift of fast-to slow-twitch muscle in SOL muscle was also retarded by the RGNS treatment. Conclusions: These findings suggested that the long-term diet of RGNS significantly prevented aging-associated muscle atrophy and reduced physical performance, and thus RGNS has a strong potential to be developed as a drug that prevents or improves sarcopenia.

• Applied Microscopy
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• v.25 no.4
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• pp.26-51
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• 1995

The present study was designed to examine effect of long term weight-training on aging atrophy in the rat skeletal muscle. Male rats of 8, 15, and 24 month old were used. Each age groups included control and weight-training for 5 months by using body press apparatus. The histo- and cytochemical, ultrastructural and stereological changes in aging skeletal muscles of the rat were observed in the present study. During the training period the body weight and muscular weight in all groups except the rectus femoris and the gastrocnemius in young age groups remained constant, but muscular weights were increased in the rectus femoris and the gastrocnemius muscles in young age groups. In trained rat, the volume density of muscle fiber type IIA and IIB were increased, but those of type IIC was decreased. Type I remained constant in 8 and 15 month old age groups, but reduced in the tibialis anterior and the gastrocnemius muscles in the 24 month old groups. Some histotological and ultrastructural changes associated with age were found: numerical increase of cytiplasmic vacuoles, lysosomes, lipofuscins, and irregularity of myofibrils. At 24 month old groups some unusual formation of contraction band and muscle splitting were observed. After weight-training, ultrastructural degenerative changes occured in the type I muscle fiber, such as splitting of muscle fiber, disorganization of myofilaments, swelling of mitochondria, accumulation of many lipid droplets, appearance of many lysosomes and residual bodies and necrotic fibers, in the old age groups. But, in the type II muscle fibers hypertrophy of muscle fiber appeared without any noticible damage as the type I. The activities of $Mg^{++}$ -ATPase decreased with age and this enzyme activities in the trained rat were significantly decreased with age. Activities of the acid phosphatase were increased with age and significantly in the trained rat. In stereological analysis, volume density of the myofibrils and the tubular system were increased, on the other hand there mitochondrial capacity was decreased. These experimental results suggested that old rats are not susceptible to be affected by weight-training as young rats, and that physical capacity of the rats must be considered when old rats are exercised for training.

• The Journal of Korean Physical Therapy
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• v.18 no.3
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• pp.9-21
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• 2006

Purpose: This study was intended to examine the effects of electroacupuncture and therapeutic exercise on muscle atrophy and exercise function in an ischemic stroke model induced by middle cerebral artery occlusion. Methods: This study selected 120 Sprangue-Dawley rats, 8-week of age, divided them into six groups, and assigned 5 rats to each group. Experiments were conducted for 1, 3 days, 1, and 8 weeks, respectively. Group I was a group of electroacupuncture and therapeutic exercise after inducing ischemic stroke; Group II was a group of therapeutic exercise after inducing ischemic stroke; Group III was a group of electroacupuncture after inducing ischemic stroke; Group IV was a sham group of electroacupuncture after inducing ischemic stroke; Group V was a control group and Group VI was a sham group without ischemic stroke. In each group, changes in weight of muscle and relative muscle of TA muscle, neurologic motor behavior test, histologic observations were observed and analyzed. Results: For the changes in muscle weight of unaffected and affected sides of TA muscle, muscle atrophy was seen in an affected side 3 days after ischemic stroke was induced. There was statistically significant difference in Group I 1 week and 8 weeks after ischemic stroke was induced, compared to Group V (p<0.05). For the changes in relative muscle weight of unaffected and affected sides of tibial anterior muscle, there was significant decrease in each group 3 days after ischemic stroke was induced, compared to Group IV, while there was statistically significant increase in Group I 1 week after ischemic stroke was induced, compared to Group V (p<0.05). For neuologic exercise behavior test, Group I generally had the highest score, compared to other groups. Conclusion: electroacupuncture and therapeutic exercise may improve muscle atrophy and change in histologic observations expression of ischemic stroke rats and contribute to the improvement of exercise function.

• Integrative Medicine Research
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• v.5 no.3
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• pp.176-181
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• 2016

Recent studies have focused on evidence-based interventions to prevent mobility decline and enhance physical performance in older adults. Several modalities, in addition to traditional strengthening programs, have been designed to manage age-related functional decline more effectively. In this study, we reviewed the current relevant literatures to assess the therapeutic potential of eccentric exercises for age-related muscle atrophy (sarcopenia). Age-related changes in human skeletal muscle, and their relationship with physical performance, are discussed with reference to in vitro physiologic and human biomechanics studies. An overview of issues relevant to sarcopenia is provided in the context of the recent consensus on the diagnosis and management of the condition. A decline in mobility among the aging population is closely linked with changes in the muscle force-velocity relationship. Interventions based specifically on increasing velocity and eccentric strength can improve function more effectively compared with traditional strengthening programs. Eccentric strengthening programs are introduced as a specific method for improving both muscle force and velocity. To be more effective, exercise interventions for older adults should focus on enhancing the muscle force-velocity relationship. Exercises that can be performed easily, and that utilize eccentric strength (which is relatively spared during the aging process), are needed to improve both muscle force and velocity.

• Journal of Nutrition and Health
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• v.56 no.6
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• pp.602-614
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• 2023

Purpose: The balance between synthesis and degradation of proteins plays a critical role in the maintenance of skeletal muscle mass. Mitochondrial dysfunction has been closely associated with skeletal muscle atrophy caused by aging, cancer, and chemotherapy. Polygalacin D is a saponin derivative isolated from Platycodon grandiflorum (Jacq.) A. DC. This study aimed to investigate the effects of polygalacin D on myoblast differentiation and muscle atrophy in association with mitochondrial function in in vitro and in zebrafish models in vivo. Methods: C2C12 myoblasts were cultured in differentiation media containing different concentrations of polygalacin D, followed by the immunostaining of the myotubes with myosin heavy chain (MHC). The mRNA expression of markers related to myogenesis, muscle atrophy, and mitochondrial function was determined by real-time quantitative reverse transcription polymerase chain reaction. Wild type AB^* zebrafish (Danio rerio) embryos were treated with 5-fluorouracil, leucovorin, and irinotecan (FOLFIRI) with or without polygalacin D, and immunostained to detect slow and fast types of muscle fibers. The Tg(Xla.Eef1a1:mitoEGFP) zebrafish expressing mitochondria-targeted green fluorescent protein was used to monitor mitochondrial morphology. Results: The exposure of C2C12 myotubes to 0.1 ng/mL of polygalacin D increased the formation of MHC-positive multinucleated myotubes (≥ 8 nuclei) compared with the control. Polygalacin D significantly increased the expression of MHC isoforms (Myh1, Myh2, Myh4, and Myh7) involved in myoblast differentiation while it decreased the expression of atrophic markers including muscle RING-finger protein-1 (MuRF1), mothers against decapentaplegic homolog (Smad)2, and Smad3. In addition, polygalacin D promoted peroxisome proliferator-activated receptor-gamma coactivator (Pgc1α) expression and reduced the level of mitochondrial fission regulators such as dynamin-1-like protein (Drp1) and mitochondrial fission 1 (Fis1). In a zebrafish model of FOLFIRI-induced muscle atrophy, polygalacin D improved not only mitochondrial dysfunction but also slow and fast muscle fiber atrophy. Conclusion: These results demonstrated that polygalacin D promotes myogenesis and alleviates chemotherapy-induced muscle atrophy by improving mitochondrial function. Thus, polygalacin D could be useful as nutrition support to prevent and ameliorate muscle wasting and weakness.

• Journal of Physiology & Pathology in Korean Medicine
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• v.22 no.6
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• pp.1454-1461
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• 2008

In oriental medicine, it is known that Eucommiae Cortex (EC) has strengthening and rehabilitative effects on the bone-muscle dysfunction. This study aimed to evaluate the effect of EC on the skeletal muscle atrophy. The muscle atrophy was induced by unilateral transection of the sciatic nerve in Sprague-Dawley rats. EC (water-extract, 170mg/100 g body weight) was treated once a day for 12 days. In this study, the effect of EC examined the muscle weight of hind limb, cross section areas of muscle fibers, fiber type compositions, apoptosis related factors (Bax and Bcl-2). EC reduced muscle atrophy in soleus (SOL), medial gastrocnemius (MGT), extensor digitorum longus, and tibialis posterior significantly in the damaged hind limb. EC increased type-I muscle fibers and decreased type-II muscle fibers significantly in SOL of the damaged hind limb. EC enlarged cross section areas of type-I and type-II muscle fibers significantly in SOL. EC enlarged cross section areas of type-I and type-II muscle fibers significantly in. EC reduced apoptotic nuclei and atrophic muscle fibers in SOL and MGT. EC reduced Bax positive muscle nuclei in SOL and MGT. EC up-regulated Bcl-2 positive muscle fibers in SOL and MGT. These results suggest that EC has an anti-atrophic effect and anti-apoptotic effect against myonuclear apoptosis induced by the peripheral nerve damage.

• The Journal of Korean Physical Therapy
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• v.2 no.1
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• pp.47-63
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• 1990

The purpose of this study was to determined the effect of low-frequency electrical stimulation on the denervated gastrocnemius muscles of the albino rats, Sprague-Dawley. Fifteen Sprague-Dawley adult male albino rats were divided into non-treated (normal) group, denervated (control) group, denervated and electrical stimulated (experiments). The gastrocnemius muscles of the right leg were submaximally stimulated with 30 Hz electrical stimulation. After 4-week period, the animals were sacrificed, and muscle were removed, fixed by immersion, and processed for light and electron microscopy. The numbers of Ag-NOR increased significantly (p<0.001), but significant reductions of girth(p<0.01), wet muscle weight (p<0.001), high glycogen content fiber (p<0.01), and mitochondrial number (p<0.05) were found in denervated control group. In comparison with control group, significant increase of right leg girth (p<0.05), wet muscle weight (p<0.001), high glycogen content fiber (p<0.05), numbers of Ag-NOR(p<0.001), number of mitochondria (p<0.01), mitochondrial volume found in electrical stimulated experimental group. The results suggest that the electrical stimulation of the muscle partially prevented the denervated atrophy in the rat gastrocnemius muscles.