Kawano F.,Osaka University |
Goto K.,Toyohashi Sozo University |
Wang X.D.,Osaka University |
Terada M.,Osaka University |
And 4 more authors.
Journal of Applied Physiology | Year: 2010
Effects of gravitationalloading or unloading on the gain of the characteristics in soleus muscle fibers were studied in rats. The tail suspension was performed in newborn rats from postnatal day 4 to month 3, and the reloading was allowed for 3 mo in some rats. Single expression of type I myosin heavy chain (MHC) was observed in ∼82% of fibers in 3-mo-old controls, but the fibers expressing multiple MHC isoforms were noted in the unloaded rats. Although 97% of fibers in 3-mo-old controls had a single neuromuscular junction at the central region of fiber, fibers with multiple nerve endplates were seen in the unloaded group. Faster contraction speed and lower maximal tension development, even after normalization with fiber size, were observed in the unloaded pure type I MHC fibers. These parameters generally returned to the age-matched control levels after reloading. It was suggested that antigravity-related tonic activity plays an important role in the gain of single neural innervation and of slow contractile properties and phenotype in soleus muscle fibers. Copyright © 2010 the American Physiological Society.
Egawa T.,Toyohashi Sozo University |
Ohno Y.,Toyohashi Sozo University |
Goto A.,Toyohashi Sozo University |
Ikuta A.,Toyohashi Sozo University |
And 7 more authors.
American Journal of Physiology - Endocrinology and Metabolism | Year: 2014
5'-AMP-activated protein kinase (AMPK) plays an important role as a negative regulator of skeletal muscle mass. However, the precise mechanism of AMPK-mediated regulation of muscle mass is not fully clarified. Heat shock proteins (HSPs), stress-induced molecular chaperones, are related with skeletal muscle adaptation, but the association between AMPK and HSPs in skeletal muscle hypertrophy is unknown. Thus, we investigated whether AMPK regulates hypertrophy by mediating HSPs in C2C12 cells. The treatment with AICAR, a potent stimulator of AMPK, decreased 72-kDa HSP (HSP72) expression, whereas there were no changes in the expressions of 25-kDa HSP, 70-kDa heat shock cognate, and heat shock transcription factor 1 in myotubes. Protein content and diameter were less in the AICAR-treated myotubes in those without treatment. AICAR-induced suppression of myotube hypertrophy and HSP72 expression was attenuated in the siRNA-mediated AMPKα knockdown myotubes. AICAR increased microRNA (miR)-1, a modulator of HSP72, and the increase of miR-1 was not induced in AMPKα knockdown condition. Furthermore, siRNA-mediated HSP72 knockdown blocked AICAR-induced inhibition of myotube hypertrophy. AICAR upregulated the gene expression of muscle Ring-finger 1, and this alteration was suppressed in either AMPKα or HSP72 knockdown myotubes. The phosphorylation of p70 S6 kinase Thr389 was downregulated by AICAR, whereas this was attenuated in AMPKα, but not in HSP72, knockdown myotubes. These results suggest that AMPK inhibits hypertrophy through, in part, an HSP72-associated mechanism via miR-1 and protein degradation pathways in skeletal muscle cells. © 2014 the American Physiological Society.
PubMed | Juntendo University, University of Tsukuba, Toyo Koso Kagaku Co., Hirosaki Gakuin University and 3 more.
Type: Journal Article | Journal: The journal of physiological sciences : JPS | Year: 2016
Extended periods of skeletal muscle disuse results in muscle atrophy and weakness. Currently, no therapeutic treatment is available for the prevention of this problem. Nonetheless, growing evidence suggests that prevention of disuse-induced oxidative stress in inactive muscle fibers can delay inactivity-induced muscle wasting. Therefore, this study tested the hypothesis that dietary supplementation with the antioxidant astaxanthin would protect against disuse muscle atrophy, in part, by prevention of myonuclear apoptosis. Wistar rats (8 weeks old) were divided into control (CT, n=9), hindlimb unloading (HU, n=9), and hindlimb unloading with astaxanthin (HU+AX, n=9) groups. Following 2weeks of dietary supplementation, rats in the HU and HU+AX groups were exposed to unloading for 7days. Seven-day unloading resulted in reduced soleus muscle weight and myofiber cross-sectional area (CSA) by~30 and~47%, respectively. Nonetheless, relative muscle weights and CSA of the soleus muscle in the HU+AX group were significantly greater than those of the HU group. Moreover, astaxanthin prevented disuse-induced increase in the number of terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL)-positive nuclei. We conclude that astaxanthin supplementation prior to and during hindlimb unloading attenuates soleus muscle atrophy, in part, by suppressing myonuclear apoptosis.
PubMed | Toyohashi Sozo University, Yamaguchi University, Kyoto University, Hirosaki Gakuin University and Doshisha University
Type: Journal Article | Journal: American journal of physiology. Endocrinology and metabolism | Year: 2015
AMPK is considered to have a role in regulating skeletal muscle mass. However, there are no studies investigating the function of AMPK in modulating skeletal muscle mass during atrophic conditions. In the present study, we investigated the difference in unloading-associated muscle atrophy and molecular functions in response to 2-wk hindlimb suspension between transgenic mice overexpressing the dominant-negative mutant of AMPK (AMPK-DN) and their wild-type (WT) littermates. Male WT (n = 24) and AMPK-DN (n = 24) mice were randomly divided into two groups: an untreated preexperimental control group (n = 12 in each group) and an unloading (n = 12 in each group) group. The relative soleus muscle weight and fiber cross-sectional area to body weight were decreased by 30% in WT mice by hindlimb unloading and by 20% in AMPK-DN mice. There were no changes in puromycin-labeled protein or Akt/70-kDa ribosomal S6 kinase signaling, the indicators of protein synthesis. The expressions of ubiquitinated proteins and muscle RING finger 1 mRNA and protein, markers of the ubiquitin-proteasome system, were increased by hindlimb unloading in WT mice but not in AMPK-DN mice. The expressions of molecules related to the protein degradation system, phosphorylated forkhead box class O3a, inhibitor of B, microRNA (miR)-1, and miR-23a, were decreased only in WT mice in response to hindlimb unloading, and 72-kDa heat shock protein expression was higher in AMPK-DN mice than in WT mice. These results imply that AMPK partially regulates unloading-induced atrophy of slow-twitch muscle possibly through modulation of the protein degradation system, especially the ubiquitin-proteasome system.
PubMed | Hirosaki Gakuin University, National Center for Geriatrics and Gerontology, Doshisha University, Toyohashi Sozo University and 2 more.
Type: Journal Article | Journal: International journal of medical sciences | Year: 2016
Effects of myostatin (MSTN)-suppression on the regeneration of injured skeletal muscle under unloading condition were investigated by using transgenic mice expressing a dominant-negative form of MSTN (MSTN-DN). Both MSTN-DN and wild-type (WT) mice were subjected to continuous hindlimb suspension (HS) for 6 weeks. Cardiotoxin (CTX) was injected into left soleus muscle under anesthesia 2 weeks after the initiation of HS. Then, the soleus muscles were excised following 6-week HS (4 weeks after CTX-injection). CTX-injection caused to reduce the soleus fiber cross-sectional area (CSA) in WT mice under both unloading and weight-bearing conditions, but not in MSTN-DN mice. Under unloading condition, CTX-injected muscle weight and fiber CSA in MSTN-DN mice were significantly higher than those in WT mice. CTX-injected muscle had many damaged and regenerating fibers having central nuclei in both WT and MSTN-DN mice. Significant increase in the population of Pax7-positive nuclei in CTX-injected muscle was observed in MSTN-DN mice, but not in WT mice. Evidences indicate that the suppression of MSTN cause to increase the regenerative potential of injured soleus muscle via the increase in the population of muscle satellite cells regardless of unloading conditions.
PubMed | Toyohashi Sozo University, Yamaguchi University, Hirosaki Gakuin University and Doshisha University
Type: Journal Article | Journal: Acta physiologica (Oxford, England) | Year: 2015
Effects of heat shock transcription factor 1 (HSF1) deficiency on heat stress-associated increase in slow soleus muscle mass of mice were investigated.Both HSF1-null and wild-type mice were randomly assigned to control and heat-stressed groups. Mice in heat-stressed group were exposed to heat stress (41 C for 60 min) in an incubator without anaesthesia.Significant increase in wet and dry weights, and protein content of soleus muscle in wild-type mice was observed seven days after the application of the heat stress. However, heat stress had no impact on soleus muscle mass in HSF1-null mice. Neither type of mice exhibited much effect of heat stress on HSF mRNA expression (HSF1, HSF2 and HSF4). On the other hand, heat stress upregulated heat shock proteins (HSPs) at the mRNA (HSP72) and protein (HSP72 and HSP110) levels in wild-type mice, but not in HSF1-null mice. The population of Pax7-positive nuclei relative to total myonuclei of soleus muscle in wild-type mice was significantly increased by heat stress, but not in HSF1-null mice. Furthermore, the absence of HSF1 gene suppressed heat stress-associated phosphorylation of Akt and p70 S6 kinase (p-p70S6K) in soleus muscle.Heat stress-associated increase in skeletal muscle mass may be induced by HSF1 and/or HSF1-mediated stress response that activates muscle satellite cells and Akt/p70S6K signalling pathway.
PubMed | Nagasaki University, Hirosaki Gakuin University, Doshisha University, Toyohashi Sozo University and 2 more.
Type: Journal Article | Journal: Acta physiologica (Oxford, England) | Year: 2016
The effects of heat shock transcription factor 1 (HSF1) deficiency on the fibre type composition and the expression level of nuclear factor of activated T cells (NFAT) family members (NFATc1, NFATc2, NFATc3 and NFATc4), phosphorylated glycogen synthase kinase 3 (p-GSK3) and p-GSK3, microRNA-208b (miR-208b), miR-499 and slow myosin heavy chain (MyHC) mRNAs (Myh7 and Myh7b) of antigravitational soleus muscle in response to unloading with or without reloading were investigated.HSF1-null and wild-type mice were subjected to continuous 2-week hindlimb suspension followed by 2- or 4-week ambulation recovery.In wild-type mice, the relative population of slow type I fibres, the expression level of NFATc2, p-GSK3 ( and ), miR-208b, miR-499 and slow MyHC mRNAs (Myh7 and Myh7b) were all decreased with hindlimb suspension, but recovered after it. Significant interactions between train and time (the relative population of slow type I fibres; P=0.01, the expression level of NFATc2; P=0.001, p-GSK; P=0.009, miR-208b; P=0.002, miR-499; P=0.04) suggested that these responses were suppressed in HSF1-null mice.HSF1 may be a molecule in the regulation of the expression of slow MyHC as well as miR-208b, miR-499, NFATc2 and p-GSK3 ( and ) in mouse soleus muscle.
Sato Y.,Nihon University |
Torii S.,University of Tokyo |
Sasaki M.,Hirosaki Gakuin University
icSPORTS 2015 - Proceedings of the 3rd International Congress on Sport Sciences Research and Technology Support | Year: 2015
Over time it has become clear that there is a relationship between visual spotting and movement in the air in gymnasts, but that relationship during basic skills that are simple for skilled gymnasts, such as a jump with full turn, is still unclear. The aim of this study was to reveal the relationship between the initiation of gaze stabilisation and the magnitude of body rotation angle during landing. The participants were 10 skilled male gymnasts. Their eye movements during jumps were measured using electrooculography and their body movements were recorded using two high-speed digital cameras. The initiation of gaze stabilisation immediately before landing was determined by combining eye and head movement data. We found various relationships between initiation of gaze stabilisation and jump movement in gymnasts, such as a positive correlation between the gaze stabilisation and the head-on-trunk angle at the initiation of gaze stabilisation and angles of trunk rotation at the landing. The results suggest that gymnasts who can look at locations quicker before landing might have an advantage in completing rotation, as well as gaining enough time to use visual information. For achieving early gaze stabilisation, it may be necessary to rotate the head ahead of the trunk. Copyright © 2015 by SCITEPRESS-Science and Technology Publications, Lda. All rights reserved.
PubMed | University of Leipzig, University of Tokyo, Nihon University and Hirosaki Gakuin University
Type: | Journal: Perceptual and motor skills | Year: 2016
When airborne, gymnasts skillfully control their movements to achieve a successful landing. Utilizing visual information from task-specific eye-body coordination patterns (i.e., visual spotting) is thought to be important for gymnasts in the performance of aerial skills. The purpose of this study was to assess the interplay of eye movements and body movements in an aerial skill with a rotation about the longitudinal axis, namely a straight jump with full turn. Participants were 10 skilled male gymnasts (age [MSD], 23.903.28 years) and 14 male nongymnasts (20.572.90 years). Gaze behavior during each jump was determined by measuring and integrating eye and head movement data. Results revealed two distinct gaze-shift patterns: a single-step gaze-shift pattern and a multistep gaze-shift pattern. In both patterns, skilled gymnasts stabilized their gaze prior to takeoff and again prior to landing. Whichever pattern was used, gymnasts started to stabilize their gaze on average about 110 milliseconds before landing, which was earlier than nongymnasts. The results suggest that gymnasts use visual information obtained by a particular gaze behavior to generate the necessary amount of rotation and to perform a precise landing in aerial skills involving whole-body rotations.
PubMed | Osaka University, Yamaguchi University, Juntendo University, Doshisha University and Hirosaki Gakuin University
Type: Journal Article | Journal: The journal of physiological sciences : JPS | Year: 2016
The effects of icing or heat stress on the regeneration of injured soleus muscle were investigated in male Wistar rats. Bupivacaine was injected into soleus muscles bilaterally to induce muscle injury. Icing (0C, 20min) was carried out immediately after the injury. Heat stress (42C, 30min) was applied every other day during 2-14days after the bupivacaine injection. Injury-related increase in collagen deposition was promoted by icing. However, the level of collagen deposition in heat-stressed animals was maintained at control levels throughout the experimental period and was significantly lower than that in icing-treated animals at 15 and 28days after bupivacaine injection. Furthermore, the recovery of muscle mass, protein content, and muscle fiber size of injured soleus toward control levels was partially facilitated by heat stress. These results suggest that, compared with icing, heat stress may be a beneficial treatment for successful muscle regeneration at least by reducing fibrosis.