Publications by authors named "Hiroyo Kondo"

39 Publications

Nucleoprotein-enriched diet enhances the protein synthesis pathway and satellite cell activation via ERK1/2 phosphorylation in the unloaded rat muscle.

Exp Physiol 2021 Apr 20. Epub 2021 Apr 20.

Department of Rehabilitation Science, Kobe University Graduate School of Health Sciences, 7-10-2 Tomogaoka, Suma-ku, Kobe, Hyogo, 654-0142, Japan.

New Findings: What is the central question of this study? The purpose of this study was to determine if the nucleotides in a nucleoprotein diet could ameliorate the unloading-associated decrease in soleus muscle mass and fiber size. What is the main finding and its importance? The results indicate that the nucleotides in the nucleoprotein-enriched diet could ameliorate the unloading-associated decrease in type I fiber size and muscle mass most likely due to the activation of protein synthesis pathways and satellite cell proliferation and differentiation via ERK1/2 phosphorylation. Thus nucleotide supplementation appears to be an effective countermeasure for muscle atrophy.

Abstract: Hindlimb unloading decreases both protein synthesis pathway and satellite cell activation results in muscle atrophy. Nucleotides are included in nucleoprotein and provide the benefits of increasing ERK1/2 phosphorylation. ERK 1/2 phosphorylation is also important in the activation of satellite cells, especially for myoblast proliferation and stimulating protein synthesis pathways. Therefore, we hypothesized that nucleotide in the nucleoproteins would ameliorate muscle atrophy via increasing the protein synthesis pathways and satellite cell activation during hindlimb unloading in rat soleus. Twenty-four female Wistar rats were divided into four groups: control rats fed a basal diet without nucleoprotein (CON), control rats fed a nucleoprotein-enriched diet (CON+NP), hindlimb unloaded rats fed a basal diet (HU), or hindlimb unloaded rats fed a NP diet (HU+NP). HU for two-weeks resulted in decreases in p70S6K- and rpS6-phosphorylation, the numbers of MyoD and myogenin, type I muscle fiber size, and muscle mass. Both CON and HU rats fed the NP diet showed an increase in ERK1/2, p70S6K- and rpS6-phosphorylation, and in the number of MyoD and myogenin compared to their basal diet groups. The NP diet also ameliorated the unloading-associated decrease in type I muscle fiber size and muscle mass. The results indicate that the nucleotides in the nucleoprotein-enriched diet could ameliorate the unloading-associated decrease in type I fiber size and muscle mass most likely due to the activation of protein synthesis pathways and satellite cell proliferation and differentiation via ERK1/2 phosphorylation. Thus nucleotide supplementation appears to be an effective countermeasure for muscle atrophy. This article is protected by copyright. All rights reserved.
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http://dx.doi.org/10.1113/EP089337DOI Listing
April 2021

Reduced metabolic capacity in fast and slow skeletal muscle via oxidative stress and the energy-sensing of AMPK/SIRT1 in malnutrition.

Physiol Rep 2021 Mar;9(5):e14763

Department of Rehabilitation Science, Kobe University Graduate School of Health Sciences, Kobe, Japan.

The effects of malnutrition on skeletal muscle result in not only the loss of muscle mass but also fatigue intolerance. It remains unknown whether the metabolic capacity is related to the fiber type composition of skeletal muscle under malnourished condition although malnutrition resulted in preferential atrophy in fast muscle. The purpose of the present study was to investigate the effects of metabolic capacity in fast and slow muscles via the energy-sensing of AMPK and SIRT1 in malnutrition. Wistar rats were randomly divided into control and malnutrition groups. The rats in the malnutrition group were provided with a low-protein diet, and daily food intake was limited to 50% for 12 weeks. Malnutrition with hypoalbuminemia decreased the body weight and induced the loss of plantaris muscle mass, but there was little change in the soleus muscle. An increase in the superoxide level in the plasma and a decrease in SOD-2 protein expression in both muscles were observed in the malnutrition group. In addition, the expression level of AMPK in the malnutrition group increased in both muscles. Conversely, the expression level of SIRT1 decreased in both muscles of the malnutrition group. In addition, malnutrition resulted in a decrease in the expression levels of PGC-1α and PINK protein, and induced a decrease in the levels of two key mitochondrial enzymes (succinate dehydrogenase and citrate synthase) and COX IV protein expression in both muscles. These results indicate that malnutrition impaired the metabolic capacity in both fast and slow muscles via AMPK-independent SIRT1 inhibition induced by increased oxidative stress.
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http://dx.doi.org/10.14814/phy2.14763DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7923585PMC
March 2021

Mild hyperbaric oxygen exposure attenuates rarefaction of capillary vessels in streptozotocin-induced diabetic soleus muscle in rats.

Biomed Res 2021 ;42(1):1-11

Department of Rehabilitation Science, Kobe University Graduate School of Health Sciences.

We examined the effects of mild hyperbaric oxygen (mHBO) exposure on capillary rarefaction in skeletal muscles of rats with diabetes. Streptozotocin (100 mg/kg) was administered to male Wistar rats via the tail vein to prepare a diabetic model. These rats were divided into 2 groups: the group with mHBO exposure (1.25 atmospheres absolute (ATA) with 36% oxygen; 3 h/day) and the group without mHBO exposure. Age-matched rats were used as the control group. Eight weeks later, the soleus of the rats was removed and then analyzed. With the onset of diabetes mellitus, capillary number, diameter, and volume in the soleus of the rats with diabetes decreased compared with those of the rats in the control group. In addition, increased anti-angiogenic thrombospondin-1 (TSP-1) and decreased pro-angiogenic murine double minute 2 (MDM-2) protein expressions were observed in the rats with diabetes. Alternatively, mHBO exposure attenuated the decrease in capillary diameter and volume in skeletal muscles of rats with diabetes, suppressed the overexpression of TSP-1, and restored the MDM-2 expression. These results indicate the exposure of mHBO partially attenuates capillary rarefaction in diabetic soleus muscle.
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http://dx.doi.org/10.2220/biomedres.42.1DOI Listing
January 2021

Preventive effects of low-intensity endurance exercise for severe hyperglycemia-induced capillary regression in non-obese type 2 diabetes rat skeletal muscle.

Physiol Rep 2021 Jan;9(2):e14712

Department of Rehabilitation Science, Kobe University Graduate School of Health Sciences, Kobe, Japan.

Although endurance exercise is effective for reducing diabetes-related capillary regression, it is difficult to prescribe high-intensity endurance exercise due to the potential worsening of complications in patients with severe hyperglycemia. Therefore, this study aimed to examine whether chronic low-intensity exercise training may prevent severe hyperglycemia-induced capillary regression of skeletal muscle in non-obese type 2 diabetes. Non-diabetic Sprague Dawley rats were assigned to a control (Con) group and an exercise (Ex) group. Likewise, spontaneously diabetic Torii rats were assigned to a diabetic sedentary (DM) group or a diabetic exercise (DMEx) group. Rats in the Ex and DMEx groups were placed on a motor-driven treadmill running at low speed (15 m/min) for 60 min/day, 5 days/week, for 14 weeks. Serum glucose levels were significantly increased in the DM group, but not in the DMEx group. Although the capillary-to-fiber ratio in the plantaris muscle was significantly lower in the DM group compared to the control group, the ratio in the DMEx group was significantly higher compared to the DM group. Moreover, the succinate dehydrogenase activity and expression levels of vascular endothelial growth factor and peroxisome proliferator-activated receptor γ coactivator-1α (PGC-1α) were reduced in the plantaris muscle of the DM group. However, those in the DMEx group were significantly higher than those in the DM group. These results indicate that low-intensity chronic endurance exercise training has the potential to prevent the progression of capillary regression in the skeletal muscles of non-obese type 2 diabetes patients with severe hyperglycemia.
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http://dx.doi.org/10.14814/phy2.14712DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7814498PMC
January 2021

Protective effects of low-intensity exercise on metabolic oxidative capacity and capillarization in skeletal muscle of non-obese diabetic rats.

Biomed Res 2020 ;41(5):227-236

Rehabilitation Science, Graduate School of Health Sciences, Kobe University.

Diabetes mellitus induces skeletal muscle dysfunction, such as decreased metabolic activity and capillarization. This study aimed to investigate the effects of aerobic low intensity exercise training on metabolic oxidative capacity and capillarization in skeletal muscle of non-obese diabetic rats. Eleven to twenty-five week-old male non-obese Spontaneous Diabetic Torii (SDT) rats (n = 11) and age-matched healthy male Sprague-Dawley SD rats (n = 11) were randomly assigned to either exercise or sedentary groups. The exercise training was performed on a low-speed motorized treadmill (15 m min) for 60 min per session, 5 sessions per week for 14 weeks in exercised groups. Sedentary SDT rats resulted in hyperglycemia, reduction of metabolic oxidative enzyme, and low percentage of oxidative fibers in the skeletal muscles. The low-intensity exercise training inhibited the growth-related increase in glucose level, and increased the muscle oxidative enzyme in exercised SDT rats compared with sedentary SDT rats. In addition, the exercise program prevented capillary regression in the skeletal muscle of diabetic rats. These results suggest that low-intensity exercise training may be an effective treatment to counter the detrimental effects of type 2 diabetes mellitus on the oxidative capacity and the capillary network of skeletal muscles.
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http://dx.doi.org/10.2220/biomedres.41.227DOI Listing
January 2020

Licorice flavonoid oil supplementation promotes a reduction of visceral fat in exercised rats.

J Sports Med Phys Fitness 2021 Mar 1;61(3):480-488. Epub 2020 Oct 1.

Department of Rehabilitation Science, Kobe University Graduate School of Health Sciences, Kobe, Japan -

Background: The beneficial effect of exercise combined with licorice flavonoid oil supplementation on visceral fat was investigated.

Methods: Male Sprague-Dawley rats were divided into 4 groups: control, exercise (Ex), control with licorice flavonoid oil supplementation (LFO), and exercise with licorice flavonoid oil supplementation (ExLFO) groups. The rats in the Ex and ExLFO groups ran on a treadmill (20-degree incline at 20 m/min for 30 min/day) 5 times a week for 7 weeks, and those in the LFO and ExLFO groups were orally administered with licorice flavonoid oil daily using a feeding needle.

Results: Exercise or licorice flavonoid oil supplementation resulted in the reduction of the visceral fat mass and adipocyte size, respectively. In addition, exercise combined with licorice flavonoid oil supplementation more effectively decreased both measures. Exercise alone increased the β-hydroxyacyl-CoA dehydrogenase (β-HAD) and citrate synthase (CS) activities in the soleus and plantaris muscles, and licorice flavonoid oil supplementation alone increased the hepatic carnitine palmitoyl transferase-2 (CPT-2) activity. Furthermore, the combination of exercise and licorice flavonoid oil supplementation enhanced the both muscular β-HAD and CS activities, and hepatic CPT-2 activity.

Conclusions: These results suggest that exercise combined with licorice flavonoid oil supplementation may be effective to decrease visceral adipose tissue via enhancing skeletomuscular and hepatic fatty acids oxidative capacity.
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http://dx.doi.org/10.23736/S0022-4707.20.11260-XDOI Listing
March 2021

High-intensity ultrasound irradiation promotes the release of extracellular vesicles from C2C12 myotubes.

Ultrasonics 2021 Feb 5;110:106243. Epub 2020 Sep 5.

Department of Rehabilitation Science, Kobe University Graduate School of Health Sciences, Kobe, Japan.

Skeletal muscle is an important secretory organ in mammals, producing myriad chemical mediators ("myokines") with distinct biological action in different tissues, including anti-inflammatory activity. Extracellular vesicles (EVs) have recently been identified as a mode of myokine transport from muscle, facilitating such anti-inflammatory activity. In this report, we have demonstrated that high-intensity ultrasound (US) strongly induces EV secretion from cultured myotubes without a reduction in cell viability. High-intensity US of 3.0 W/cm with 20% duty cycle increased the number of EVs by 2-fold compared to control at 6 h. This effect was specific to EVs in the 100-150 nm size range. Thus, high-intensity US is a novel modality for inducing myocellular EV release and may hold therapeutic value.
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http://dx.doi.org/10.1016/j.ultras.2020.106243DOI Listing
February 2021

Preventive effects of medium-chain triglycerides supplementation on the oxidative capacity in skeletal muscle under cachectic condition.

Biomed Res 2020 ;41(4):179-186

Department of Rehabilitation Science, Kobe University Graduate School of Health Sciences.

Cachexia is a multifactorial condition characterized by muscle mass loss and induces metabolic dysfunction of the skeletal muscles. The preventive effects of medium-chain triglycerides (MCT) supplementation on the oxidative capacity in skeletal muscle under cachectic condition were investigated in the present study. ICR mice were randomly divided into four groups; control, lipopolysaccharide (LPS), LPS plus long-chain triglycerides (LCT) and LPS plus MCT supplementation. LCT and MCT oil were administered to the LPS + LCT and LPS + MCT groups orally (5.0 g/kg body weight/day) by a catheter for one week. Cachexia was induced in the LPS, LPS + LCT, and LPS + MCT groups via LPS injection (7.5 mg/kg body weight, i.p.) after the supplementation. LPS induced a reduction of ketone bodies concentration in blood plasma. LPS also induced a decrease in succinate dehydrogenase activity and PGC-1α expression level in tibialis anterior muscles. Meanwhile, MCT supplementation suppressed a decrease in ketone bodies concentration and succinate dehydrogenase activity. In addition, MCT supplementation increased the level of citrate synthase activity in the muscles. These results suggested the preventive effect of MCT supplementation on oxidative capacity in skeletal muscle and the involvements of ketone bodies regulation under cachectic condition.
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http://dx.doi.org/10.2220/biomedres.41.179DOI Listing
January 2020

Acute effects of lactic acid-fermented and enzyme-digested soybean on protein synthesis via mTOR signaling in the skeletal muscle.

Biosci Biotechnol Biochem 2020 Nov 22;84(11):2360-2366. Epub 2020 Jul 22.

Department of Rehabilitation Science, Kobe University Graduate School of Health Sciences , Kobe, Japan.

Protein-containing nutrients result in the efficient hypertrophy of muscles by increasing muscle protein synthesis. Soybean is often ingested by athletes or individuals who exercise; however, it takes very long to be absorbed. Lactic acid-fermented and enzyme-digested (LFED) soybean is absorbed faster than untreated soybean. This study aims at determining muscle protein synthesis after ingesting a single bolus of soybean or LFED soybean produced by lactic acid bacteria and protease digestion. Eight-week-old overnight-fasted ICR mice were administered powdered or LFED soybean. Mice were euthanized at 7, 15, 30, 60, 90, and 120 min after soybean intake. We have demonstrated that LFED soybean administration was quicker in stimulating muscle protein synthesis by activating mammalian target of rapamycin (mTOR) signaling than orally ingesting untreated soybean in the gastrocnemius muscle. These results suggested that LFED soybean is a more efficient source of nutrition for muscle hypertrophy than untreated soybean.
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http://dx.doi.org/10.1080/09168451.2020.1795810DOI Listing
November 2020

Protective Effects of Astaxanthin Supplementation against Ultraviolet-Induced Photoaging in Hairless Mice.

Biomedicines 2020 Jan 21;8(2). Epub 2020 Jan 21.

Department of Rehabilitation Science, Kobe University Graduate School of Health Sciences, 7-10-2 Tomogaoka, Suma-ku, Kobe, Hyogo 654-0142, Japan.

Ultraviolet (UV) light induces skin photoaging, which is characterized by thickening, wrinkling, pigmentation, and dryness. Astaxanthin (AST), a ketocarotenoid isolated from , has been extensively studied owing to its possible effects on skin health as well as UV protection. In addition, AST attenuates the increased generation of reactive oxygen species (ROS) and capillary regression of the skeletal muscle. In this study, we investigated whether AST could protect against UV-induced photoaging and reduce capillary regression in the skin of HR-1 hairless mice. UV light induces wrinkle formation, epidermal thickening, and capillary regression in the dermis of HR-1 hairless mice. The administration of AST reduced the UV-induced wrinkle formation and skin thickening, and increased collagen fibers in the skin. AST supplementation also inhibited the generation of ROS, decreased wrinkle formation, reduced epidermal thickening, and increased the density of capillaries in the skin. We also found an inverse correlation between wrinkle formation and the density of capillaries. An association between photoaging and capillary regression in the skin was also observed. These results suggest that AST can protect against photoaging caused by UV irradiation and the inhibitory effects of AST on photoaging may be associated with the reduction of capillary regression in the skin.
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http://dx.doi.org/10.3390/biomedicines8020018DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7168265PMC
January 2020

Transcutaneous carbon dioxide attenuates impaired oxidative capacity in skeletal muscle in hyperglycemia model.

Gen Physiol Biophys 2019 May;38(3):237-244

Department of Rehabilitation Science, Kobe University Graduate School of Health Sciences, Suma-ku, Kobe-shi, Hyogo, Japan.

Hyperglycemia impairs oxidative capacity in skeletal muscle. Muscle oxidative capacity is regulated by peroxisome proliferator-activated receptor-γ co-activator-1α (PGC-1α). Transcutaneous carbon dioxide (CO2) enhances PGC-1α expression in skeletal muscle. Therefore, the aim of this study was to clarify the effects of CO2 therapy on muscle oxidative capacity impaired by streptozotocin (STZ)-induced hyperglycemia. Eight-week-old male Wistar rats were randomly divided into 4 groups: control, CO2 treatment, STZ-induced hyperglycemia, and STZ-induced hyperglycemia treated with CO2. STZ-induced hyperglycemia resulted in a decrease of muscle oxidative capacity and decreased PGC-1α and cytochrome c oxidase subunit 4 (COX-4) expression levels; while, application of transcutaneous CO2 attenuated this effect, and enhanced the expression levels of endothelial nitric oxide synthesis (eNOS). These results indicate that transcutaneous CO2 improves impaired muscle oxidative capacity via enhancement of eNOS and PGC-1α-related signaling in the skeletal muscle of rats with hyperglycemia.
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http://dx.doi.org/10.4149/gpb_2018048DOI Listing
May 2019

Application of transcutaneous carbon dioxide improves capillary regression of skeletal muscle in hyperglycemia.

J Physiol Sci 2019 Mar 26;69(2):317-326. Epub 2018 Nov 26.

Department of Rehabilitation Science, Kobe University Graduate School of Health Sciences, 7-10-2 Tomogaoka, Suma-ku, Kobe, Hyogo, 654-0142, Japan.

The purpose of the present study was to determine the effects of transcutaneous CO application on the blood flow and capillary architecture of the soleus muscle in rats with streptozotocin (STZ)-induced hyperglycemia. Wistar rats were randomly divided into four groups: control, control + CO-treated, STZ-induced hyperglycemia, and STZ-induced hyperglycemia + CO-treated groups. Blood flow in soleus muscle increased during the transcutaneous CO exposure, and continued to increase for 30 min after the treatment. In addition, the transcutaneous CO attenuated a decrease in capillary and the expression level of eNOS and VEGF protein, and an increase in the expression level of MDM-2 and TSP-1 protein of soleus muscle due to STZ-induced hyperglycemia. These results indicate that the application of transcutaneous CO could improve capillary regression via the change of pro- and anti-angiogenesis factors, which might be induced by an increase in blood flow.
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http://dx.doi.org/10.1007/s12576-018-0648-yDOI Listing
March 2019

Protective effects of Brazilian propolis supplementation on capillary regression in the soleus muscle of hindlimb-unloaded rats.

J Physiol Sci 2019 Mar 19;69(2):223-233. Epub 2018 Sep 19.

Department of Rehabilitation Science, Kobe University Graduate School of Health Sciences, 7-10-2 Tomogaoka, Suma-ku, Kobe, Hyogo, 654-0142, Japan.

The protective effects of Brazilian propolis on capillary regression induced by chronically neuromuscular inactivity were investigated in rat soleus muscle. Four groups of male Wistar rat were used in this study; control (CON), control plus Brazilian propolis supplementation (CON + PP), 2-week hindlimb unloading (HU), and 2-week hindlimb unloading plus Brazilian propolis supplementation (HU + PP). The rats in the CON + PP and HU + PP groups received two oral doses of 500 mg/kg Brazilian propolis daily (total daily dose 1000 mg/kg) for 2 weeks. Unloading resulted in a decrease in capillary number, luminal diameter, and capillary volume, and an increase in the expression of anti-angiogenic factors, such as p53 and TSP-1, within the soleus muscle. Brazilian propolis supplementation, however, prevented these changes in capillary structure due to unloading through the stimulation of pro-angiogenic factors and suppression of anti-angiogenic factors. These results suggest that Brazilian propolis is a potential non-drug therapeutic agent against capillary regression induced by chronic unloading.
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http://dx.doi.org/10.1007/s12576-018-0639-zDOI Listing
March 2019

Mild hyperbaric oxygen inhibits the growth-related decline in skeletal muscle oxidative capacity and prevents hyperglycemia in rats with type 2 diabetes mellitus.

J Diabetes 2018 Sep 17;10(9):753-763. Epub 2018 May 17.

Laboratory of Cell Biology and Life Science, Graduate School of Human and Environmental Studies, Kyoto University, Kyoto, Japan.

Background: Humans and animals with type 2 diabetes mellitus (T2DM) exhibit low skeletal muscle oxidative capacity and impaired glucose metabolism. The aim of the present study was to investigate the effects of exposure to mild hyperbaric oxygen on these changes in obese rats with T2DM.

Methods: Five-week-old non-diabetic Long-Evans Tokushima Otsuka (LETO) and diabetic Otsuka Long-Evans Tokushima Fatty (OLETF) rats were divided into normobaric (LETO-NB and OLETF-NB) and mild hyperbaric oxygen (LETO-MHO and OLETF-MHO) groups. The LETO-MHO and OLETF-MHO groups received 1266 hPa with 36% oxygen for 3 h daily for 22 weeks.

Results: Fasting and non-fasting blood glucose, HbA1c, and triglyceride levels were lower in the OLETF-MHO group than in the OLETF-NB group (P < 0.05). In the soleus muscle, peroxisome proliferator-activated receptor δ/β (Pparδ/β), Pparγ, and PPARγ coactivator-1α (Pgc-1α) mRNA levels were lower in the OLETF-NB group than in all other groups (P < 0.05), whereas myogenin (Myog) and myogenic factor 5 (Myf5) mRNA levels were higher in the OLETF-MHO group than in the LETO-NB and OLETF-NB groups (P < 0.05). The soleus muscles in the OLETF-NB group contained only low-oxidative Type I fibers, whereas those in all other groups contained high-oxidative Type IIA and Type IIC fibers in addition to Type I fibers.

Conclusions: Exposure to mild hyperbaric oxygen inhibits the decline in skeletal muscle oxidative capacity and prevents the hyperglycemia associated with T2DM. Pgc-1α, Myog, and Myf5 mRNA levels appear to be closely associated with skeletal muscle oxidative capacity in rats with T2DM.
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http://dx.doi.org/10.1111/1753-0407.12666DOI Listing
September 2018

Enterococcus faecium strain R30 increases red blood cell velocity and prevents capillary regression in the soleus of hindlimb-unloaded rats via the eNOS/VEGF pathway.

Microcirculation 2017 05;24(4)

Department of Rehabilitation Science, Graduate School of Health Sciences, Kobe University, Kobe, Japan.

Objective: A chronic decrease in neuromuscular activity results in atrophy and capillary regression in skeletal muscles. The purposes of this study were to determine the effects of Enterococcus faecium strain R30 (R30) administration on (i) the hemodynamics of the rat soleus muscle, and (ii) the capillary regression normally associated with HU.

Methods: Experiment 1: The V was measured for up to 1 hour after administration of R30 with or without the β-blocker propranolol. Experiment 2: R30 was administered daily to control and HU rats for 2 weeks. Mean capillary luminal diameter, volume, and the levels of eNOS and VEGF protein were measured.

Results: Experiment 1: V was faster 20, 40, and 60 minutes after than before the administration of R30: This effect was suppressed by propranolol administration. Experiment 2: R30 administration during HU increased capillary luminal diameter and volume and eNOS and VEGF protein levels in the soleus of HU rats.

Conclusions: The results suggest that R30 increases V in the soleus muscle via muscle sympathetic nerve activity (Experiment 1) and that R30 supplementation lessens the capillary regression normally associated with HU via the eNOS/VEGF pathway (Experiment 2).
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http://dx.doi.org/10.1111/micc.12356DOI Listing
May 2017

Nucleoprotein supplementation enhances the recovery of rat soleus mass with reloading after hindlimb unloading-induced atrophy via myonuclei accretion and increased protein synthesis.

Nutr Res 2016 Dec 23;36(12):1335-1344. Epub 2016 Oct 23.

Rehabilitation Science, Graduate School of Health Sciences, Kobe University, 7-10-2 Tomogaoka, Kobe 654-0142, Japan. Electronic address:

Hindlimb unloading results in muscle atrophy and a period of reloading has been shown to partially recover the lost muscle mass. Two of the mechanisms involved in this recovery of muscle mass are the activation of protein synthesis pathways and an increase in myonuclei number. The additional myonuclei are provided by satellite cells that are activated by the mechanical stress associated with the reloading of the muscles and eventually incorporated into the muscle fibers. Amino acid supplementation with exercise also can increase skeletal muscle mass through enhancement of protein synthesis and nucleotide supplements can promote cell cycle activity. Therefore, we hypothesized that nucleoprotein supplementation, a combination of amino acids and nucleotides, would enhance the recovery of muscle mass to a greater extent than reloading alone after a period of unloading. Adult rats were assigned to 4 groups: control, hindlimb unloaded (HU; 14 days), reloaded (5 days) after hindlimb unloading (HUR), and reloaded after hindlimb unloading with nucleoprotein supplementation (HUR + NP). Compared with the HUR group, the HUR + NP group had larger soleus muscles and fiber cross-sectional areas, higher levels of phosphorylated rpS6, and higher numbers of myonuclei and myogenin-positive cells. These results suggest that nucleoprotein supplementation has a synergistic effect with reloading in recovering skeletal muscle properties after a period of unloading via rpS6 activation and satellite cell differentiation and incorporation into the muscle fibers. Therefore, this supplement may be an effective therapeutic regimen to include in rehabilitative strategies for a variety of muscle wasting conditions such as aging, cancer cachexia, muscular dystrophy, bed rest, and cast immobilization.
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http://dx.doi.org/10.1016/j.nutres.2016.10.007DOI Listing
December 2016

L-arginine supplementation attenuates capillary regression without increasing integrated succinate dehydrogenase activity and VEGF expression in skeletal muscle during hindlimb unloading.

Gen Physiol Biophys 2016 Oct 22;35(4):425-432. Epub 2016 Jul 22.

Department of Rehabilitation Science, Kobe University, Graduate School of Health Sciences, 7-10-2 Tomogaoka, Suma-ku, Kobe 654-0142, Japan.

Decreased capillary number is observed in atrophied muscle. The change in capillary number is regulated by angiogenic factors. L-arginine enhances expression of endothelial nitric oxide synthase (eNOS), angiogenic factor, in skeletal muscle. Therefore, the aim of this study was to evaluate the effects of L-arginine supplementation on capillary regression during hindlimb unloading. Twenty-four male Wistar rats were divided into four treatment groups: (1) control, (2) L-arginine supplementation, (3) hindlimb unloading, and (4) hindlimb unloading with L-arginine supplementation. Hindlimb unloading resulted in a decrease of capillary-to-muscle fibre (C/F) ratio, eNOS expression, and integrated succinate dehydrogenase (SDH) activity. L-arginine supplementation attenuated the decrease in both eNOS expression and C/F ratio, although it did not increase integrated SDH activity in skeletal muscle. These results indicate that L-arginine supplementation is effective for maintaining capillary number in atrophied muscle, and that elevation of eNOS expression may be one mechanism associated with these responses.
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http://dx.doi.org/10.4149/gpb_2016016DOI Listing
October 2016

Astaxanthin supplementation attenuates immobilization-induced skeletal muscle fibrosis via suppression of oxidative stress.

J Physiol Sci 2017 Sep 6;67(5):603-611. Epub 2016 Oct 6.

Department of Rehabilitation Science, Kobe University Graduate School of Health Sciences, 7-10-2 Tomogaoka, Suma-ku, Kobe-shi, Hyogo, 654-0142, Japan.

Immobilization induces skeletal muscle fibrosis characterized by increasing collagen synthesis in the perimysium and endomysium. Transforming growth factor-β1 (TGF-β1) is associated with this lesion via promoting differentiation of fibroblasts into myofibroblasts. In addition, reactive oxygen species (ROS) are shown to mediate TGF-β1-induced fibrosis in tissues. These reports suggest the importance of ROS reduction for attenuating skeletal muscle fibrosis. Astaxanthin, a powerful antioxidant, has been shown to reduce ROS production in disused muscle. Therefore, we investigated the effects of astaxanthin supplementation on muscle fibrosis under immobilization. In the present study, immobilization increased the collagen fiber area, the expression levels of TGF-β1, α-smooth muscle actin, and superoxide dismutase-1 protein and ROS production. However, these changes induced by immobilization were attenuated by astaxanthin supplementation. These results indicate the effectiveness of astaxanthin supplementation on skeletal muscle fibrosis induced by ankle joint immobilization.
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http://dx.doi.org/10.1007/s12576-016-0492-xDOI Listing
September 2017

Effectiveness of daily eccentric contractions induced via kilohertz frequency transcutaneous electrical stimulation on muscle atrophy.

Acta Histochem 2016 Jan 25;118(1):56-62. Epub 2015 Nov 25.

Department of Rehabilitation Science, Kobe University Graduate School of Health Sciences, 7-10-2 Tomogaoka, Kobe 654-0142, Japan. Electronic address:

The effects of daily repeated bouts of concentric, isometric, or eccentric contractions induced by high frequency (kilohertz) transcutaneous electrical stimulation in ameliorating atrophy of the soleus muscle in hindlimb unloaded rats were determined. Five groups of male rats were studied: control, hindlimb unloaded for 2 weeks (HU), or HU plus two daily bouts of concentric, isometric, or eccentric high-frequency electrical stimulation-induced contractions of the calf musculature. Soleus mass and fiber size were smaller, the levels of phosphorylated Akt1 and FoxO3a lower, and atrogin-1 and ubiquitinated proteins higher in the HU, and the HU plus concentric or isometric contraction groups than in the control group. In contrast, daily bouts of eccentric contractions maintained these values at near control levels and all measures were significantly different from all other HU groups. These results indicate that daily bouts of eccentric contractions induced by high-frequency stimulation inhibited the ubiquitin-proteasome catabolic pathway and enhanced the Akt1/FoxO3a anabolic pathway that resulted in a prevention of the atrophic response of the soleus muscle to chronic unloading.
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http://dx.doi.org/10.1016/j.acthis.2015.11.007DOI Listing
January 2016

Abnormalities in three-dimensional capillary architecture and imbalance between vascular endothelial growth factor-A and thrombospondin-1 in soleus muscle of ovariectomized rat.

Acta Histochem 2015 Sep 16;117(7):605-11. Epub 2015 Jun 16.

Department of Rehabilitation Science, Kobe University Graduate School of Health Sciences, 7-10-2 Tomogaoka, Kobe 654-0142, Japan. Electronic address:

Reduced ovarian hormone levels associated with menopause or ovariectomy (OVX) not only result in vascular dysfunction but also lead to structural abnormalities in capillaries. Therefore, the effect of OVX on the three-dimensional (3-D) architecture of capillary networks and the underlying molecular mechanisms were investigated in rat soleus muscle. Seven-week-old female Wistar rats were divided into the OVX and sham-treated (Sham) groups. The OVX group exhibited lower endurance exercise capacity compared to the sham group and resulted in decreased capillary diameter, number of anastomoses and capillary/anastomosis volume in soleus muscle, indicating 3-D structural abnormalities of capillary networks. Furthermore, OVX led to increased concentrations of thrombospondin-1 (TSP-1) protein and a decreased VEGF-A/TSP-1 ratio, an indicator of angio-adaptations, in soleus muscle compared with the Sham group. These results indicate OVX may induce 3-D capillary regression in soleus muscle through an imbalance between VEGF-A and TSP-1 expression, possibly associated with decreased exercise tolerance in ovariectomized rats.
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http://dx.doi.org/10.1016/j.acthis.2015.06.001DOI Listing
September 2015

Effects of microgravity on the mouse triceps brachii muscle.

Muscle Nerve 2015 Jul 29;52(1):63-8. Epub 2015 May 29.

Department of Interdisciplinary Science, Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, Sagamihara, Japan.

Introduction: In this study we investigated the effects of microgravity on the fiber properties of the mouse triceps brachii, a forelimb muscle that has no antigravity function.

Methods: Mice (n = 7) were exposed to microgravity for 13 days on the space shuttle Atlantis (Space Transportation System-135). The fiber cross-sectional area (CSA) and succinate dehydrogenase (SDH) staining intensity of the triceps brachii muscle were compared with those of controls (n = 7). SDH activity in this muscle was also estimated.

Results: Microgravity did not affect the body weight, muscle weight, or fiber CSA, but there was reduced SDH staining intensity of all types of fibers, irrespective of the muscle region (P < 0.05). Microgravity also reduced muscle SDH activity (P < 0.05).

Conclusions: Short-term exposure to microgravity induced a decrease in oxidative capacity, but not atrophy, in the triceps brachii muscle of mice.
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http://dx.doi.org/10.1002/mus.24491DOI Listing
July 2015

Influence of estrogen receptor α polymorphisms on bone density in response to habitual exercise in Japanese postmenopausal women.

ScientificWorldJournal 2014 23;2014:593927. Epub 2014 Jul 23.

Laboratory of Cell Biology and Life Science, Graduate School of Human and Environmental Studies, Kyoto University, Kyoto 606-8501, Japan.

Estrogen receptor α (ER α) is one of candidate genes for osteoporosis. This study examined the influence of ER α gene, PvuII, and XbaI genotypes on bone density of calcaneus in response to habitual exercise. ER α polymorphisms were detected using PvuII and XbaI restriction enzymes in 316 Japanese postmenopausal women. The bone density was significantly lower in the women carrying PP, pp, or xx genotype without habitual exercise than in the age-matched women without those genotypes. The women carrying Pp genotype without habitual exercise had normal bone density compared to those without Pp genotype. The women carrying PPxx or ppxx polymorphism without habitual exercise had low bone density compared to those with habitual exercise. Thus, the reduction of bone density was attenuated in the women carrying PPxx or ppxx with habitual exercise. In addition, habitual exercise was highly effective for the bone density in the women carrying xx homozygote. These findings indicate that analyses of XbaI and PvuII polymorphisms of ER α may be useful to predict the effect of exercise on bone density, and habitual exercise attenuates the reduction of bone density in women with some genotypes.
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http://dx.doi.org/10.1155/2014/593927DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4134819PMC
March 2015

Low-intensity running exercise enhances the capillary volume and pro-angiogenic factors in the soleus muscle of type 2 diabetic rats.

Muscle Nerve 2015 Mar 6;51(3):391-9. Epub 2015 Jan 6.

Department of Food Science and Nutrition, Nagoya Women's University, Nagoya, Japan.

Introduction: We determined the effects of low-intensity exercise on the three-dimensional capillary structure and associated angiogenic factors in the soleus muscle of Goto-Kakizaki (GK) diabetic rats.

Methods: Four groups of male rats were studied: sedentary nondiabetic (Con), exercised nondiabetic control (Ex), sedentary GK, and exercised GK (GK+Ex). Rats in the Ex and GK+Ex groups were subjected to chronic low-intensity running on a treadmill (15 m/min, 60 min/session, 5 sessions/week for 3 weeks).

Results: Although mean capillary volume and diameter were lower in the GK compared with all other groups, low-intensity exercise increased both of these measures in GK rats. Mitochondrial markers, i.e., SDH activity and PGC-1α expression, and the levels of angiogenic factors were higher in the GK+Ex than all other groups. Exercise increased vascular endothelial growth factor (VEGF) protein levels and the VEGF-to-TSP-1 ratio, an indicator of angiogenesis, in GK rats.

Conclusions: Combined, the results indicate that low-intensity exercise reduces some of the microcirculatory complications in type 2 diabetic muscles.
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http://dx.doi.org/10.1002/mus.24316DOI Listing
March 2015

Amelioration of capillary regression and atrophy of the soleus muscle in hindlimb-unloaded rats by astaxanthin supplementation and intermittent loading.

Exp Physiol 2014 Aug 6;99(8):1065-77. Epub 2014 Jun 6.

Department of Rehabilitation Science, Kobe University Graduate School of Health Sciences, Kobe, Japan

A chronic decrease in neuromuscular activity (activation and/or loading) results in muscle atrophy and capillary regression that are due, in part, to the overproduction of reactive oxygen species. We have reported that antioxidant treatment with astaxanthin attenuates the overexpression of reactive oxygen species in atrophied muscles that, in turn, ameliorates capillary regression in hindlimb-unloaded rats. Astaxanthin supplementation, however, had little effect on muscle mass and fibre cross-sectional area. In contrast, intermittent loading of the hindlimbs of hindlimb-unloaded rats ameliorates muscle atrophy. Therefore, we hypothesized that the combination of astaxanthin supplementation and intermittent loading would attenuate both muscle atrophy and capillary regression during hindlimb unloading. As expected, 2 weeks of hindlimb unloading resulted in atrophy, a decrease in capillary volume and a shift towards smaller-diameter capillaries in the soleus muscle. Intermittent loading alone (1 h of cage ambulation per day) attenuated atrophy of the soleus, while astaxanthin treatment alone maintained the capillary network to near control levels. The combination of intermittent loading and astaxanthin treatment, however, ameliorated atrophy of the soleus and maintained the capillary volume and luminal diameters and the superoxide dismutase-1 protein levels near control values. These results indicate that intermittent loading combined with astaxanthin supplementation could be an effective therapy for both the muscle atrophy and the capillary regression associated with a chronic decrease in neuromuscular activity.
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http://dx.doi.org/10.1113/expphysiol.2014.079988DOI Listing
August 2014

Decreased succinate dehydrogenase activity of gamma and alpha motoneurons in mouse spinal cords following 13 weeks of exposure to microgravity.

Neurochem Res 2013 Oct 14;38(10):2160-7. Epub 2013 Aug 14.

Laboratory of Cell Biology and Life Science, Graduate School of Human and Environmental Studies, Kyoto University, Sakyo-ku, Kyoto, 606-8501, Japan,

Cell body size and succinate dehydrogenase activity of motoneurons in the dorsolateral region of the ventral horn in the lumbar and cervical segments of the mouse spinal cord were assessed after long-term exposure to microgravity and compared with those of ground-based controls. Mice were housed in a mouse drawer system on the International Space Station for 13 weeks. The mice were transported to the International Space Station by the Space Shuttle Discovery and returned to Earth by the Space Shuttle Atlantis. No changes in the cell body size of motoneurons were observed in either segment after exposure to microgravity, but succinate dehydrogenase activity of small-sized (<300 μm(2)) gamma and medium-sized (300-700 μm(2)) alpha motoneurons, which have higher succinate dehydrogenase activity than large-sized (>700 μm(2)) alpha motoneurons, in both segments was lower than that of ground-based controls. We concluded that exposure to microgravity for longer than 3 months induced decreased succinate dehydrogenase activity of both gamma and slow-type alpha motoneurons. In particular, the decreased succinate dehydrogenase activity of gamma motoneurons was observed only after long-term exposure to microgravity.
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http://dx.doi.org/10.1007/s11064-013-1124-yDOI Listing
October 2013

Chronic Exercise Training Down-Regulates TNF-α and Atrogin-1/MAFbx in Mouse Gastrocnemius Muscle Atrophy Induced by Hindlimb Unloading.

Acta Histochem Cytochem 2012 Dec 27;45(6):343-9. Epub 2012 Oct 27.

Department of Rehabilitation Science, Kobe University, Graduate School of Health Sciences, 7-10-2 Tomogaoka, Suma-ku, Kobe 654-0142, Japan.

The purpose of this study was to investigate the effect of chronic moderate-intensity training in order to prevent muscle atrophy with a focus on TNF-α and atrogin-1/MAFbx as main proteolytic indicators. Hindlimb unloading model of mice received treadmill running exercise for 1 hr per day during hindlimb unloading period of 6 weeks. The gastrocnemius muscle mass, muscle fiber cross-sectional area, and succinate dehydrogenase (SDH) activity in the muscle fiber were higher in the exercised group, while TNF-α and atrogin-1/MAFbx mRNA expressions were significantly lower. Results in the present study showed that chronic exercise could prevent over expression of TNF-α and atrogin-1/MAFbx in the atrophied skeletal muscle, providing further support to the effects of chronic exercise training on muscle atrophy.
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http://dx.doi.org/10.1267/ahc.12023DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3554785PMC
December 2012

Abnormalities in the fiber composition and capillary architecture in the soleus muscle of type 2 diabetic Goto-Kakizaki rats.

ScientificWorldJournal 2012 7;2012:680189. Epub 2012 Nov 7.

Department of Physical Therapy, Himeji Dokkyo University, Himeji, Hyogo 670-8524, Japan.

Type 2 diabetes mellitus is linked to impaired skeletal muscle glucose uptake and storage. This study aimed to investigate the fiber type distributions and the three-dimensional (3D) architecture of the capillary network in the skeletal muscles of type 2 diabetic rats. Muscle fiber type transformation, succinate dehydrogenase (SDH) activity, capillary density, and 3D architecture of the capillary network in the soleus muscle were determined in 36-week-old Goto-Kakizaki (GK) rats as an animal model of nonobese type 2 diabetes and age-matched Wistar (Cont) rats. Although the soleus muscle of Cont rats comprised both type I and type IIA fibers, the soleus muscle of GK rats had only type I fibers. In addition, total SDH activity in the soleus muscle of GK rats was significantly lower than that in Cont rats because GK rats had no high-SDH activity type IIA fiber in the soleus muscle. Furthermore, the capillary diameter, capillary tortuosity, and microvessel volume in GK rats were significantly lower than those in Cont rats. These results indicate that non-obese diabetic GK rats have muscle fiber type transformation, low SDH activity, and reduced skeletal muscle capillary content, which may be related to the impaired glucose metabolism characteristic of type 2 diabetes.
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http://dx.doi.org/10.1100/2012/680189DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3504414PMC
June 2013

Oxygen concentration-dependent oxidative stress levels in rats.

Oxid Med Cell Longev 2012 4;2012:381763. Epub 2012 Sep 4.

Laboratory of Cell Biology and Life Science, Graduate School of Human and Environmental Studies, Kyoto University, Kyoto 606-8501, Japan.

Introduction: We determined derivatives of reactive oxygen metabolites (dROMs) as an index of oxidative stress level (oxidant capacity) and biochemical antioxidant potential (BAP) as an index of antioxidant capacity in rats exposed to different oxygen concentrations.

Methods: Male Wistar rats were exposed to 14.4%, 20.9%, 35.5%, 39.8%, 62.5%, and 82.2% oxygen at 1 atmosphere absolute for 24 h. Serum levels of dROMs and BAP were examined by using a free radical and antioxidant potential determination device. The morphological characteristics of red blood cells were examined by phase contrast microscopy.

Results: There were no differences in the levels of dROMs in rats exposed to 14.4%, 20.9%, and 35.5% oxygen. However, the levels of dROMs increased in the rats exposed to 39.8% and 62.5% oxygen. The levels of dROMs were the highest in the rats exposed to 82.2% oxygen. There were no differences in the levels of BAP with respect to the oxygen concentration. Morphological changes in the red blood cells induced by oxidative attack from reactive oxygen species were observed in the rats exposed to 39.8%, 62.5%, and 82.2% oxygen.

Conclusion: Our results suggest that exposure to oxygen concentrations higher than 40% for 24 h induces excessive levels of oxidative stress in rats.
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http://dx.doi.org/10.1155/2012/381763DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3440952PMC
January 2013

Exercise training prevents decrease in luminal capillary diameter of skeletal muscles in rats with type 2 diabetes.

ScientificWorldJournal 2012 13;2012:645891. Epub 2012 Aug 13.

Department of Rehabilitation Science, Kobe University Graduate School of Health Sciences, 7-10-2 Tomogaoka, Suma-ku, Kobe, Japan.

The purpose of this study was to examine whether exercise training can prevent microangiopathy of skeletal muscles in rats with type 2 diabetes and if succinate dehydrogenase (SDH) activity, an indicator of mitochondrial oxidative enzyme activity, is involved in the prevention of microangiopathy. Six-week-old male Goto-Kakizaki (GK) rats and age-matched male Wistar rats (control group (Con)) were used. GK rats were randomly assigned to nonexercise (DB) and exercise (DBEx) groups. The DBEx group was trained on a treadmill 5 times a week for 3 weeks. No significant differences in the capillary-to-fibre ratio or the capillary density were observed between the 3 groups. The luminal capillary diameter of the DB group was significantly lower than that of the Con group, whereas the capillary diameter of the DBEx group was significantly higher than that of the DB group. In addition, SDH activity was significantly higher in the DBEx group than in the Con and DB groups. Microangiopathy of skeletal muscles in type 2 diabetes was correlated with a decrease in the luminal capillary diameter, which was prevented by exercise training. Thus, the mitochondrial oxidative capacity appears to be involved in the overall mechanism by which exercise prevents microangiopathy.
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http://dx.doi.org/10.1100/2012/645891DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3425813PMC
March 2013

Effects of hyperbaric oxygen on metabolic capacity of the skeletal muscle in type 2 diabetic rats with obesity.

ScientificWorldJournal 2012 18;2012:637978. Epub 2012 Jun 18.

Department of Rehabilitation Science, Kobe University Graduate School of Health Sciences, 7-10-2 Tomogaoka, Suma-ku, Kobe 654-0142, Japan.

We investigated whether hyperbaric oxygen enhances the oxidative metabolic capacity of the skeletal muscle and attenuates adipocyte hypertrophy in type 2 diabetic rats with obesity. Five-week-old male Otsuka Long-Evans Tokushima fatty (OLETF) and Long-Evans Tokushima Otsuka (LETO) rats were used as diabetic animals and nondiabetic controls, respectively, and assigned to control and hyperbaric oxygen groups. Animals in the hyperbaric oxygen group were exposed to an atmospheric pressure of 1.25 with an oxygen concentration of 36% for 3 h daily. The glucose level at 27 weeks of age was significantly higher in OLETF rats than in LETO rats, but the elevation was inhibited in OLETF rats exposed to hyperbaric oxygen. The slow-to-fast fiber transition in the skeletal muscle was observed in OLETF rats, but the shift was inhibited in OLETF rats exposed to hyperbaric oxygen. Additionally, the oxidative enzyme activity of muscle fibers was increased by hyperbaric oxygen. The adipocyte size was larger in OLETF rats than in LETO rats, but hypertrophied adipocytes were not observed in OLETF rats exposed to hyperbaric oxygen. Hyperbaric oxygen enhances glucose and lipid metabolism in the skeletal muscle, indicating that hyperbaric oxygen can prevent elevation of glucose and adipocyte hypertrophy in diabetic rats with obesity.
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http://dx.doi.org/10.1100/2012/637978DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3385605PMC
October 2012