Low-intensity Exercise Group Research Articles

The Effect of Pre-Scuba Diving Exercise Intensity on Vein Bubble Formation after Scuba Diving

PURPOSE This study was to investigate the effects of pre-scuba diving exercise intensity on vein bubble formation after scuba diving. METHODS The participants were divided into four groups: Non-Exercise group (NEG/n=20) and Low Intensity-Exercise group (LEG/ n=20) and Moderate Intensity-Exercise group (MEG/n=20) and High Intensity-Exercise group (HEG/n=20). The LEG group and MEG group and HEG group took part in the exercise program on pre-scuba diving. RESULTS The results of this study were as follows: First, As for the Subclavian vein of Left bubble grade, there were significantly increased in NEG group and MEG group and HEG group. Second, As for the Subclavian vein of Right bubble grade, there were significantly increased in NEG group and MEG group and HEG group. Third. As for the Right atrium of bubble grade. There were significantly increased in NEG group and MEG group and HEG group. CONCLUSIONS As conclusions, this study confirmed that the pre-scuba diving exercise intensity could improve the vein bubble formation of scuba diver. 색인어: ìŠ¤ì¿ ë²„ 다이빙, 운동강도, ì •ë§¥ê¸°í¬í˜•ì„±, ìŠ¤ì¿ ë²„ 다이버 Keywords: Scuba diving, Exercise intensity, Vein bubble formation, Scuba diver

High-intensity interval training increase GATA4, CITED4 and c-Kit and decreases C/EBPβ in rats after myocardial infarction

AimMyocardial infarction (MI), an important cause of morbidity and mortality, can be followed by left ventricular dysfunction and cardiomyocyte loss. Cardiac repair mechanisms may subsequently improve left ventricular function. Exercise training has been suggested to have cardioprotective effects against MI damage, but detailed knowledge is lacking on the effects of different types and intensities of exercise training on molecular targets of cardiomyocyte regeneration. Main methodsMI was induced in male Wistar rats by ligating the left anterior descending coronary artery. After MI induction, the rats were randomly assigned to one of five groups: sham operated, and experimental MI followed by no exercise, or low, moderate or high intensity exercise Cardiac function and infarct size were assessed by echocardiography and Evans blue/TTC staining, respectively. The expression of mRNA markers and proteins associated with myocardial regeneration was measured with RT-PCR and western blotting. Key findingsExercise training at different intensities improved cardiac function and levels of stem cell and cardiomyocyte markers, and reduced infarct size. mRNA levels of GATA4, Nkx2.5 and c-Kit and protein expression of Nkx2.5 and c-Kit were significantly increased in all MI-exercise groups. The high-intensity exercise group had greater increases than the low and moderate intensity exercise groups. In the high-intensity exercise group, Sca-1 and CITED4 increased more than in the low-intensity exercise group. C/EBPβ mRNA and protein levels decreased after exercise training, with greater reductions in the high-intensity exercise group than the low- or moderate-intensity groups. SignificanceThe findings suggest that by targeting cardiogenesis, high-intensity training can exert cardioprotective effects against cardiac dysfunction in an experimental model of MI.

Effect of prior chronic aerobic exercise on overload-induced skeletal muscle hypertrophy in mice.

This study aimed to examine how regular aerobic training can affect the muscle hypertrophy induced by overloading. Male C57BL/6J mice were randomly divided into three groups: rest group, low-intensity aerobic exercise group, and high-intensity aerobic exercise group. Mice in the exercise groups were assigned to run at a speed of 10 m/min (low-intensity) or 25 m/min (high-intensity) for 30 min/day, five days/week, for four weeks. Then, the right hind leg gastrocnemius muscles were surgically removed to overload the plantaris and soleus muscles, while the left hind leg was subjected to a sham-operation. Both the plantaris and soleus muscles grew larger in the overloaded legs than those in the sham-operated legs. Muscle growth increased in the plantaris muscles in the low-intensity exercise group compared to that in the rest or high-intensity exercise groups at one and two weeks after overloading. This enhancement was not observed in the soleus muscles. Consistently, we observed changes in the expression of proteins involved in anabolic intracellular signaling, including Akt, mechanistic target of rapamycin (mTOR), and p70S6K, in the plantaris muscles. Our data showed for the first time that chronic low-intensity aerobic exercise precipitates overload-induced muscle growth.

PO-128 Effects of 30%, 50%, 70%VO2 max treadmill exercises on gut microbiome of atherosclerotic mice

Objective To observe the dynamic changes of gut microbiome in mice before and after different intensities of treadmill exercises, and to explore the effects of different intensities of treadmill exercises on gut microbiome of atherosclerotic (AS) mice.
 Methods The 50 male ApoE-/- mice aged 8 weeks were randomly divided into 2 groups, 10 mice in the general feeding group and the other 40 mice in the AS group, which were fed with normal and high-fat diet for 4 weeks respectively. Weight and blood test were taken before and after 4 weeks feeding. The serum Triglyceride (TG), total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein (HDL) levels were examined by blood test in ApoE-/- mice model, and atherosclerotic disease degeneration score of adult mice was used to determine the success of modeling after 4 weeks feeding. Then two mice selected from the normal and high-fat group respectively selected to test the maximum oxygen uptake (VO2 max) by the reformative Bedford method, and the running platform speed and slope corresponding to 30%, 50% and 70%VO2 max were determined. The 40 AS mice were randomly divided into the model blank group, the low-intensity exercise group, the medium-intensity exercise group and the high-intensity exercise group according to their weight for 4 weeks of exercises, respectively. The low-intensity exercise group was 30% VO2 max, with a slope of 10 degrees and a speed of 10 m/min. The medium intensity exercise group was 50% VO2 max with a slope of 10 degrees and a speed of 15 m/min. The high-intensity exercise group was 70% VO2 max with a slope of 10 degrees and a speed of 20 m/min. The exercises were performed for 4 weeks, 5 days a week, 20 minutes a day. The fresh feces were collected from 5 groups of mice before and after 4 weeks treadmill exercises. The number of gut Lactobacillus, Bacteroides, Firmicutes, Bifidobacterium, Verrucomicrobiaceae, Akkermansia , Escherichia coli, Collinsella and Clostridium in AS mice were analyzed by 16s sequencing. 
 Results 1. The TG, TC and LDL-C were significantly increased in the blood serum of the mice after the modeling, and the HDL-C was decreased, and the atherosclerotic disease degeneration score was significantly increased in the adult mice, and the modeling was successful. 2. The different intensity treadmill exercises can increase the number of gut probiotics in mice and decrease the number of harmful bacteria. The beneficial bacteria in gut tract of AS mice with moderate intensity of 50% VO2max was observed in the experiment: Bacteroides, Bifidobacterium and Verrucomicrobiaceae, Akkermansia were significantly increased, P<0.05. The harmful bacteria:Lactobacillus, Escherichia coli, Collinsella and Clostridium were significantly decreased, P<0.05. The ratio of Firmicutes / Bacteroidetes was increased.
 Conclusions 1. High-fat diet can lead to AS in ApoE-/- mice. 2. The different intensity treadmill exercises can reduce the weight of AS mice. 3. The number and abundance of probiotics of gut microbiome of AS mice could be promoted by different intensity treadmill exercises, among which the medium intensity aerobic exercise can significantly increase the number of beneficial bacteria such Bacteroidetes, Bifidobacteria, Verrucomicrobiaceae and Akkermansia, meanwhile, the structure of gut microbiome in AS mice was improved as well.

PO-239 Normal signal transduction pathways of rat habitual endurance exercise at different intensities

Objective A signal transduction pathway is always signal-specific, but it becomes special in exercise physiology, especially for habitual exercise training. In this paper, the normal signal transduction pathways (NPs) of habitual endurance exercise of Sprague-Dawly (SD) rats at different intensities were studied in terms of self-similar algorithm .
 Methods 1. SD rats were randomly divided into a control group with no exercise (Cont), a low-intensity exercise group (LI) at 15 m/min for 60 min, a medium-intensity exercise group (MI) at 25 m/min for 40 min, and a high-intensity exercise group (HI) 35 m/min for 30 min. The the treadmill exercise began at 10 m/min for 10 min. The speed and time increased by 5 m/min and by 5 min respectively after every two days until the intensity was OK for LI, MI and HI groups. All rats in the exercise groups were trained for eight weeks. The muscle was collected two hours after the last training. The 20 parameters, the expression of PGC-1α, PI3K, AMPK, p38MAPK, SIRT1, IGF-1, Akt, mTOR, TFAM, NRF1 and NRF2 and the level of T, CS, SDH, β-HAD, MDH, HK, PK, LDH and HSL, were assessed. 2. The 20 dimension data sets were integratedly analyzed with self-similar algorithm.
 Results 1. The first-order self-similarity held for the 20 dimension data sets between MI and HI groups. 2. There was one biomarker, PGC-1α, between Cont and LI groups with respect to HI group which parameters were used to be dimensionless for Cont and LI groups. 3. There were two biomarkers, PGC-1α and PI3K, between LI and MI or HI groups with respect cont group.
 Conclusions The NP of LI group may be PGC-1α pathway, and the NPs of MI or HI group may be PGC-1α and PI3K pathways.

Effects of exhaustive exercises, with different intensities, on oxidative stress markers in rat plasma and skeletal muscle

Summary Objectives The purpose of this study was to examine the effects of exhaustive exercises, with different intensities, on oxidative stress markers in rat plasma and skeletal muscle. Methods Male Sprague-Dawley rats (n = 24) were randomly divided into the following four groups: control (CON), low-intensity exercise (LE), high-intensity interval exercise (HE) and incremental exercise (IE). The animals in the latter three groups performed exercises in which they ran until exhaustion as follows: Animals in the LE group ran at 20 m/min (6° graded); the HE group ran at 40 m/min for 30 s (0° graded) with a rest interval of 60 s between each run; and the IE group ran at 15 m/min (6° graded), initially, with the running speed gradually increased by 5 m/min, every 10 min. Immediately following the exercise, a blood sample was drawn, and followed by the gastrocnemius muscle and liver were quickly removed. These samples were analysed for lactate concentration, oxidative stress markers, and glycogen contents. Results Plasma oxidative stress markers in the LE and HE groups demonstrated no change, while plasma protein carbonyl (PC) levels and total antioxidant capacity (TAC) in the IE group were significantly increased compared with the CON group (P Conclusion Incremental exhaustive exercise elevates the plasma PC levels and TAC, but does not change skeletal muscle oxidative stress markers in rats.

EFFECT OF 12-WEEK LOW-INTENSITY EXERCISE ON INTERLEUKIN-2, INTERFERON-GAMMA AND INTERLEUKIN-4 CYTOKINE PRODUCTION IN RAT SPLEENS

Background and Objective
 High-intensity exercise has been linked to immunity; however, the relationship between low-intensity exercise and the immune system is unclear. In this study, the effects of exercise on cytokine production in T helper 1 (interleukin-2 [IL-2] and interferon-gamma [INF-g]) and T helper 2 cells (interleukin-4 [IL-4]) in spleens were investigated.
 Material and Methods
 Sprague–Dawley male rats were divided into a control group (CON, n = 10) and a low-intensity exercise group (EX, n = 10). EX rats were trained on a treadmill (8 m/min, 50 min/day, 5 times over 12 weeks). Spleen tissues were analyzed by hematoxylin-eosin staining and real-time PCR to quantify IL-4, INF-γ, and IL-2 expression.
 Results
 IL-4 expression was significantly higher in the EX group than in the CON group (p < 0.05). However, IL-2 and INF-γ expression did not differ between groups (p > 0.05).
 Conclusion
 These results suggest that exercise in rats enhances immune function by regulating cytokine production in T helper type 2 (IL-4) cells, but not in T helper type 1 (IL-2 and IFN-g) cells of the activated spleen.

Effects of Exercise Intensity on Alcohol Dehydrogenase Gene Expression in the Rat Large IntestineExercise and ADH Gene Expression

Background and Objective
 The aim of this study was to examine the relationship between the intensity of treadmill exercise and alcohol dehydrogenase (ADH) expression in the large intestine.
 Material and Methods
 Thirty Sprague-Dawley white male rats were randomly assigned to a control group (CON; no exercise), low-intensity exercise group (LIG; 30-min exercise at 8 m/min 5 times a week for 4 weeks), or high-intensity exercise group (HIG; 30-min exercise at 28 m/min 5 times a week for 4 weeks).
 Results
 Microarray analysis was conducted to evaluate ADH gene expression levels in large intestinal tissue, significant changes in the expression of four ADH genes (Adh1, Adh4, Adh6a, and Adh7) related to exercise intensity. In addition, pooled samples of the exercise groups showed decreased expression levels of these four genes compared with those of the control group. These findings were confirmed by reverse transcription-polymerase chain reaction. In addition, differences were detected with respect to exercise intensity: Adh1, Adh4, and Adh6a levels were significantly decreased in the LIG compared with those in the HIG, whereas Adh7 expression showed an opposite trend.
 Conclusion
 In conclusion, this study suggests that regular exercise can decrease the incidence of alcohol-related disease by suppressing ADH production in the digestive system.

장기간 저강도 복합운동이 여성 노인의 기능체력, 보행속도 및 신체조성에 미치는 영향

This research aimed to verify the effects of a long term low-intensity combined exercise program as an exercise intervention on functional fitness, gait speed, and body composition in elderly women. A total of 24 subjects were assigned to low-intensity exercise group(n=12) and control group(n=12) randomly. A 60 minute Otago exercise was applied to them as the intervention 3 times a week for 32 weeks by RPE 9-12. Functional fitness was measured by Senior Fitness Test. Gait speed was measured by 10m distance divided by the second. Items for body composition consisted of height, weight, BMI, WHR, skinfold thickness(triceps, subscapular), %fat, %LBM, Fat, LBM, Fat/height, and LBM/height. Mean and standard deviations were calculated by using SPSS Version 22.0. A two-way repeated measures ANOVA was conducted to verify interactions between pre-post measurement and groups. Statistical significance was set at p.05. This research showed that there were significant interactions between time and groups in 30- second chair stand(p.01), 30-second arm curl(p.05), back scratch(p.01) and 8-foot up-and-go(p.05), gait speed(p.001) for low-intensity combined exercise group. Significant increases appeared between groups in 30-second chair stand(p.05), and 30-second arm curl(p.001) for low- intensity combined exercise group. Significant increase appeared between time in 30-second chair stand(p.05), and back scratch(p.05), gait speed(p.05) for low-intensity combined exercise group. It showed significant changes between pre-mid measurements in triceps(p.01) for low-intensity combined exercise group. With low -intensity RPE 9-12 for a long term, this combined exercise program can be used as an effective and safe exercise intervention to reduce triceps skinfold thickness and improve lower body strength, upper body strength, dynamic balance, agility, gait speed and prevent falls for elderly women living in a community.

Aerobic exercise of low to moderate intensity corrects unequal changes in BK(Ca) subunit expression in the mesenteric arteries of spontaneously hypertensive rats.

Accumulating evidence indicates that hypertension is associated with "ion channel remodeling" of vascular smooth muscle cells (VSMCs). The objective of this study was to determine the effects of exercise intensity/volume on hypertension-associated changes in large-conductance Ca(2+)-activated K(+) (BK(Ca)) channels in mesenteric arteries (MAs) from spontaneously hypertensive rats (SHR). Male SHRs were randomly assigned to three groups: a low-intensity aerobic exercise group (SHR-L: 14 m/min), a moderate-intensity aerobic exercise group (SHR-M: 20 m/min), and a sedentary group (SHR). Age-matched Wistar-Kyoto rats (WKYs) were used as normotensive controls. Exercise groups completed an 8-week exercise program. Elevation of the alpha and beta1 proteins was unequal in MA myocytes from SHRs, with the beta1 subunit increasing more than the alpha subunit. BK(Ca) contribution to vascular tone regulation was higher in the myocytes and arteries of SHRs compared to WKYs. SHR BK(Ca) channel subunit protein expression, beta1/alpha ratio, whole cell current density and single-channel open probability was also increased compared with WKYs. Aerobic exercise lowered systemic blood pressure and normalized hypertension-associated BK(Ca) alterations to normotensive control levels in the SHRs. These effects were more pronounced in the moderate-intensity group than in the low-intensity group. There is a dose-effect for aerobic exercise training in the range of low to moderate-intensity and accompanying volume for the correction of the pathological adaptation of BK(Ca) channels in myocytes of MAs from SHR.

Effects of Detraining on Ach, AchE, β-amyloid, Apolipoprotein Expression and Cognitive Function in Brain Tissue of Memory Impairment Rats

PURPOSE The purpose of this study was to investigate the effects of detraining on ACh, AChE, β-amyloid, apolipoprotein expression and cognitive function in brain tissue of memory impairment rats. METHODS Sparague-Dawley rats (n=40) were randomly divided into 4 groups (age=7 weeks, n=10 in each group): control group (CON), scopolamine-induced control group (SCO-CON), scopolamine+low intensity exercise group (SCO-LEX), and scopolamine+high intensity exercise group (SCO-HEX). The exercise groups were trained progressively on a treadmill, five days per a week for eight weeks following treadmill running programs: i) low intensity (1-4 weeks: 10 m/min for 30 min, 5-8 weeks: 12 m/min for 30 min), ii) high intensity (1-4 weeks: 15 m/min for 30 min, 5-8 weeks: 16 m/min for 30 min). After 8 weeks-exercise programming, detraining was conducted for the same period. RESULTS After detraining for 8 weeks, both exercise groups significantly increased Ach concentration compared with SCO-CON. Exercise groups significantly reduced AChE activity, β-amyloid and ApoE ε4 protein volumes compared to the SCO-CON. Both exercise groups showed a significant decrease of escape latency compared to the control group. CONCLUSIONS In spite of the effects of detraining, regular exercise is still considered to have a positive influence on the changes of memory impairment related factors. 색인어: 운동중지, 스코폴라민, 인지기능, 기억손상, 콜린성 ì‹œìŠ¤í œ Keywords: Detraining, Scopolamine, Cognitive function, Memory impairment, Cholinergic

4주 유산소 운동의 운동강도가 노령 생쥐의 심혈관질환위험인자, 활성산소, 항산화효소에 미치는 효과

Purpose: The purpose of this study was to determine the effects of different intensity of aerobic exercise for four weeks on cardiovascular risk factors, reactive oxygen, and antioxidant enzymes in old mice. Methods: Eighteen male C57BL/6 mice age 18 months were randomly classified into the control group (n=6), the moderate intensity exercise group (n=6), and the low intensity exercise group (n=6). The training groups performed the aerobic exercise twice daily for 20 minutes, five days weekly for four weeks. Data were analyzed using descriptive statistics, analysis of variance (ANOVA), the Chi-square test, and the Tukey’s test with the SPSSWIN 21.0 program. Results: In this study, among the risk factors of cardiovascular disease, blood sugar (BS) (p=.023) and total cholesterol (TC) (p=.001) were significantly different between the moderate intensity exercise group and the control group. Additionally, there were significant differences in the reactive oxygen malondialdehyde (MDA) (p=.001), the antioxidant enzymes superoxide dismutase (SOD) (p<.001) and glutathione reductase (GR) (p=.015) between the moderate intensity exercise group and the control group. Conclusion: This finding suggests that moderate intensity aerobic exercise promotes the activity of antioxidant enzymes and lowers cardiovascular risk factors in older mice. Key Words: Exercise; Glutathione Peroxidase; Malondialdehyde; Risk Factor; Superoxide Dismutase Key Words: ë ¸ë ¹ 생쥐; 운동; 심혈관위험인자; 활성산소; 항산화효소

Intensity-dependent effect of treadmill running on typeIICollagen of knee articular cartilage in rats

Objective To investigate the effect of treadmill running with different intensities on typeⅡcollagen (Col2) of knee joint articular cartilages in rats. Methods A total of 48 adult Sprague-Dawley rats were randomly divided into a control (C) group, a low-intensity exercise (L) group, a moderate- intensity exercise (M) group and a high-intensity exercise (H) group, each of 12. Rats in three exercises groups were regularly trained on treadmill at low, moderate, and high intensities respectively. Eight weeks later, all the animals were sacrificed. The right tibial plateau samples were collected to observe collagen fibers under polarizing light microscopy, and the collagenⅡ content were examined using immunohistochemistry. The mRNA expression of biglycan (BGN), fibromodulin (FMOD) and Col2 was tested using the quantitative real-time reverse transcription-polymerase chain reaction. Results Compared with group C, collagen fibers in group L and M exhibited almost the same organization, whereas, alteration in organization and shape of collagen fibers was found in group H. Significantly lower content of type Ⅱ collagen was found in group H than that in group C. In comparison with group C, group L had significantly higher gene expression of Col2, whereas group H had significantly higher BGN mRNA expression. Conclusion Low- or moderate-intensity treadmill running appears to have beneficial effect on articular cartilages to maintain its integrity. High-intensity exercises induce lower content and disorder of type Ⅱ collagen in articular cartilages, but the self-healing of cartilage may still exist. Key words: Cartilage; Type Ⅱ collagen; Treadmill running; SLRPs

Exercise intensity and the expression of toll-like receptor 4 and nuclear transcription factor-κB in the diabetic liver

Objective To investigate the changes in toll-like receptor 4 (TLR4) and nuclear transcription factor-κB (NF-κB) expression in the livers of diabetic rats after exercise at different intensities. Methods Fifty Sprague-Dawley rats were randomly divided into a control group (NC), a diabetic group (DM), a low intensity exercise group (LIE), a medium intensity exercise group (MIE) and a high intensity exercise group (HIE), each of 10. The control group was given a normal diet. Type 2 diabetes was induced in the others through feeding a high-fat and high-sugar diet, as well as injecting a small dose of streptozotocin intraperitoneally. The three exercising groups swam to 40%, 70% and 100% of their exhaustion times once a day, 6 d/w for 6 weeks. Due to infection, drowning and other reasons, only 8 rats in each of the DM, LIE and MIE groups, as well as 7 in the HIE group survived. After the intervention, body weight, liver weight and fasting blood glucose (FBG) were tested. The expression of TLR4 and NF-κB mRNA in the livers was tested using RT-PCR technology, and the expression of TLR4 and NF-κB protein in the liver was tested using immunohistochemistry. Results Compared with the NC group, the average body weight and liver weight of the other four groups decreased significantly, while the FBG and the expression of TLR4 and NF-κB mRNA and protein increased significantly. There were significant differences among the exercise groups with the lowest values in the MIE group. Conclusion Six weeks of aerobic exercise can reduce FBG and the level of expression of TLR4 and NF-κB mRNA and protein in the liver, at least in rats. The effect of exercise at medium intensity is best. Key words: Exercise; Diabetes mellitus; Liver; Toll-like receptor 4; Nuclear transcription factor-κB

Data on mitochondrial function in skeletal muscle of old mice in response to different exercise intensity.

Endurance exercise is securely linked to muscle metabolic adaptations including enhanced mitochondrial function (“Effects of exercise on mitochondrial oxygen uptake and respiratory enzyme activity in skeletal muscle” [1], “Effects of exercise on mitochondrial content and function in aging human skeletal muscle” [2]). However, the link between exercise intensity and mitochondrial function in aging muscle has not been fully investigated. In order to understand how strenuous exercise affects mitochondrial function in aged mice, male C57BL/6 mice at age 24 months were randomly assigned to 3 groups: non-exercise (NE), low-intensity (LE) and high-intensity treadmill exercise group (HE). Mitochondrial complex activity and respiration were measured to evaluate mitochondrial function in mouse skeletal muscle. The data described here are related to the research article entitled “Strenuous exercise induces mitochondrial damage in skeletal muscle of old mice” [3].

Influence of regular exercise on gastric emptying in healthy men: a pilot study.

Functional gastrointestinal disorders (FGIDs), including functional dyspepsia (FD), are common chronic disorders even in the younger population. Physical activity is advocated for patients with FGIDs, although the evidence is insufficient. We investigated the association between the intensity of regular exercise and gastric emptying to determine the effect of physical activity on dyspeptic symptoms. Thirty healthy individuals were selected and divided into three groups (low, moderate, and high) using the index of total exercise intensity in a week. Gastric emptying was evaluated by the 13C-acetate breath test. Gastroesophageal reflux symptoms, dyspeptic symptoms, stool forms, scores of anxiety and depression, and scores of sleep quality were also compared. Baseline scores of gastroesophageal reflux symptoms, anxiety, depression, and sleep quality were not different among the three groups. Gastric emptying was significantly faster in low-intensity exercise group than the moderate-intensity exercise group. Although the presence of loose stool and alcohol consumption were also associated with the intensity of regular exercise, these variables were not confounders. In conclusion, the intensity of regular exercise was independently associated with gastric emptying in healthy individuals. These baseline data would be useful for consideration of an optimal exercise intervention for the treatment of FD.

Low intensity exercise prevents disturbances in rat cardiac insulin signaling and endothelial nitric oxide synthase induced by high fructose diet

Increase in fructose consumption together with decrease in physical activity contributes to the development of metabolic syndrome and consequently cardiovascular diseases. The current study examined the preventive role of exercise on defects in cardiac insulin signaling and function of endothelial nitric oxide synthase (eNOS) in fructose fed rats. Male Wistar rats were divided into control, sedentary fructose (received 10% fructose for 9 weeks) and exercise fructose (additionally exposed to low intensity exercise) groups. Concentration of triglycerides, glucose, insulin and visceral adipose tissue weight were determined to estimate metabolic syndrome development. Expression and/or phosphorylation of cardiac insulin receptor (IR), insulin receptor substrate 1 (IRS1), tyrosine-specific protein phosphatase 1B (PTP1B), Akt, extracellular signal-regulated protein kinases 1 and 2 (ERK1/2) and eNOS were evaluated. Fructose overload increased visceral adipose tissue, insulin concentration and homeostasis model assessment index. Exercise managed to decrease visceral adiposity and insulin level and to increase insulin sensitivity. Fructose diet increased level of cardiac PTP1B and pIRS1 (Ser307), while levels of IR and ERK1/2, as well as pIRS1 (Tyr 632), pAkt (Ser473, Thr308) and pERK1/2 were decreased. These disturbances were accompanied by reduced phosphorylation of eNOS at Ser1177. Exercise managed to prevent most of the disturbances in insulin signaling caused by fructose diet (except phosphorylation of IRS1 at Tyr 632 and phosphorylation and protein expression of ERK1/2) and consequently restored function of eNOS. Low intensity exercise could be considered as efficient treatment of cardiac insulin resistance induced by fructose diet.

Activation of autophagy in human skeletal muscle is dependent on exercise intensity and AMPK activation.

In humans, nutrient deprivation and extreme endurance exercise both activate autophagy. We hypothesized that cumulating fasting and cycling exercise would potentiate activation of autophagy in skeletal muscle. Well-trained athletes were divided into control (n = 8), low-intensity (LI, n = 8), and high-intensity (HI, n = 7) exercise groups and submitted to fed and fasting sessions. Muscle biopsy samples were obtained from the vastus lateralis before, at the end, and 1 h after a 2 h LI or HI bout of exercise. Phosphorylation of ULK1(Ser317) was higher after exercise (P < 0.001). In both the fed and the fasted states, LC3bII protein level and LC3bII/I were decreased after LI and HI (P < 0.05), while p62/SQSTM1 was decreased only 1 h after HI (P < 0.05), indicating an increased autophagic flux after HI. The autophagic transcriptional program was also activated, as evidenced by the increased level of LC3b, p62/SQSTM1, GabarapL1, and Cathepsin L mRNAs observed after HI but not after LI. The increased autophagic flux after HI exercise could be due to increased AMP-activated protein kinase α (AMPKα) activity, as both AMPKα(Thr172) and ACC(Ser79) had a higher phosphorylation state after HI (P < 0.001). In summary, the most effective strategy to activate autophagy in human skeletal muscle seems to rely on exercise intensity more than diet.

운동 강도 차이가 고지방식이 Sprague-Dawley Rat의 골격근 내 PGC-1α, PPAR-γ 및 인슐린 저항에 미치는 영향

This study investigated the effects of exercise intensity on PGC-1α, PPAR-γ, and insulin resistance in skeletal muscle of high fat diet-fed Sprague-Dawley rats. Forty rats were randomly divided into five groups: sedentary control group (SED), high fat diet group (HF), high fat diet+low-intensity exercise group (HFLE, 22 m/min, 60 min, 6 days/week), high fat diet+moderate-intensity exercise group (HFME, 26 m/min, 51 min), and high fat diet+high-intensity exercise group (HFHE, 30 m/min, 46 min). After 4 weeks of high fat diet and endurance exercise training, the lipid profiles, insulin, and glucose concentrations were determined in plasma. PGC-1α, PPAR-γ, and GLUT-4 contents were measured in plantaris muscle. The rate of glucose transport in soleus muscle was determined under submaximal insulin concentration (1,000 μIU/mL insulin, 20 min) during muscle incubation. Plasma glucose during oral glucose tolerance test in HF was significantly greater than that in SED, and plasma glucose levels in the three exercise (EX) groups were significantly lower that those in SED and HF at 30 and 60 min, respectively (P<0.05). Plasma insulin levels in the EX groups were significantly reduced by 60 min compared to that in HF (P<0.05). The protein expression level of PGC-1α as well as muscle glucose uptake were significantly higher in SED and HF than those in the three EX groups (P<0.05), and HFHE showed significantly higher levels than HFLE and HFME. Expression levels of GLUT-4 and PPAR-γ were significantly higher in the HFLE, HFME, and HFHE groups compared to the SED and HF (P<0.05). Therefore, the results of this study indicate that 4 weeks of high fat diet significantly developed whole body insulin resistance but did not affect PGC-1α, PPAR-γ, or the glucose transport rate in skeletal muscle, and exercise training was able to attenuate deteriorated whole body insulin resistance due to high fat diet. In addition, high intensity training significantly affected PGC-1α expression and the glucose transport rate of skeletal muscle in comparison with low and middle training intensities.

트레드밀 운동이 뼈관절염 흰쥐의 척수 내 IL-1β 발현에 미치는 영향

PURPOSE: This study examined the effects of treadmill exercise of diverse intensities on the expression of IL-<TEX>$1{\beta}$</TEX> (interleukine-<TEX>$1{\beta}$</TEX>) in the spinal cord in osteoarthritis rats. METHODS: The authors applied treadmill exercise of diverse intensity for 4 weeks to Sprague-Dawley rats to which intra-articular injection of monosodium iodoacetate(MIA, <TEX>$3mg/50{\mu}l$</TEX>, diluted in saline) was applied in the right knee joint to induce osteoarthritis. The four-week exercise was not applied to the control group(CG, n=15), while exercise of applicable intensity was applied to the low-intensity exercise group(LEG, n=15), moderate-intensity exercise group (MEG, n=15), and high-intensity exercise group(HEG, n=15) for four weeks. Observations were made of expression of IL-<TEX>$1{\beta}$</TEX> in the spinal cord in osteoarthritis rats using western blot analysis. RESULTS: There were significant differences(p<.05) in the comparison of expression of IL-<TEX>$1{\beta}$</TEX> in the spinal cord between the four groups involved. And the LEG and MEG had reduced expression of IL-<TEX>$1{\beta}$</TEX> significantly than the CG(p<.05); in particular, the MEG showed the lowest expression. On the other hand, the HEG had more elevated expression of IL-<TEX>$1{\beta}$</TEX> significantly than the CG(p<.05). CONCLUSION: As a result, factors that induce neuropathic pain such as IL-<TEX>$1{\beta}$</TEX> are reduced; thus, the recovery of damaged neurons is improved and neuropathic pain is reduced. Further, when prescribing exercise to treat osteoarthritis patients, exercise of moderate intensity suitable for patients' physical conditions, rather than high intensity, maximizes the effects of this therapy.