Defecation enhances cerebral perfusion and delays fatigue in elite triathletes.

BACKGROUND: Rectal distension increases regulatory burden to autonomic nervous system in the brain. PURPOSE: To determine the effect of rectal defecation on endurance performance and blood supply to the prefrontal brain and sub-navel regions of elite triathletes. METHODS: Thirteen elite triathletes completed a cycling time trial (80% VO2max) under defecated and non-defecated conditions, using a counterbalanced crossover design. Oxygenation and blood distribution in prefrontal brain and sub-navel regions were monitored by near-infrared spectroscopy (NIRS) during cycling. RESULTS: Defecation moderately decreased systolic blood pressure (-4 mmHg, p < 0.05, d = 0.71), suggesting an alleviation of autonomic nervous activity. During the exercise trials, fatigue (cycling time to exhaustion) occurred when cerebral oxygenation decreased to ~ 5 % below baseline regardless of treatment conditions, suggesting a critical deoxygenation point for sustaining voluntary exertions. Cerebral blood (estimated by total hemoglobin) increased progressively throughout the entire exercise period. Defecation decreased sub-navel oxygenation levels below the non-defecated level, suggesting an increased sub-navel oxygen consumption. Exercise also decreased sub-navel blood distribution, with minimal difference between non-defecated and defecated conditions. Defecation improved blood pooling in the prefrontal brain during exercise (p < 0.05) and enhanced cycling performance in triathletes (Non-defecated: 1624 ± 138 s vs. defecated: 1902 ± 163 s, d = 0.51, p < 0.05). CONCLUSION: Our results suggest that improved exercise performance after defecation is associated with greater blood availability to compensate deoxygenation in the prefrontal brain region during exercise. Further investigation is needed to examine the role of increasing sub-navel oxygen consumption in the performance improvement after defecation.

Senolytic effect of high intensity interval exercise on human skeletal muscle.

p16INK4a expression is a robust biomarker of senescence for stem cells in human tissues. Here we examined the effect of exercise intensity on in vivo senescence in skeletal muscle, using a randomized counter-balanced crossover design. Biopsied vastus lateralis of 9 sedentary men (age 26.1 ± 2.5 y) were assessed before and after a single bout of moderate steady state exercise (SSE, 60% maximal aerobic power) and high intensity interval exercise (HIIE, 120% maximal aerobic power) on a cycloergometer accumulating same amount of cycling work (in kilojoule). Increases in cell infiltration (+1.2 folds), DNA strand break (+1.3 folds), and γ-H2AX+ myofibers (+1.1 folds) occurred immediately after HIIE and returned to baseline in 24 h (p < 0.05). Muscle p16Ink4a mRNA decreased 24 h after HIIE (-57%, p < 0.05). SSE had no effect on cell infiltration, p16Ink4a mRNA, and DNA strand break in muscle tissues. Senescence-lowering effect of HIIE was particularly prominent in the muscle with high pre-exercise p16INK4a expression, suggesting that exercise intensity determines the level of selection pressure to tissue stem cells at late senescent stage in human skeletal muscle. This evidence provides an explanation for the discrepancy between destructive nature of high intensity exercise and its anti-aging benefits.

Effects of Hypoxia-Hyperoxia Preconditioning on Indicators of Muscle Damage After Acute Resistance Exercise in Male Athletes.

Purpose: The purpose of this study was to investigate the effects of acute repeated hypoxia-hyperoxia preconditioning on resistance exercise (RE)-induced muscle damage in male athletes. Methods: Eleven young male athletes participated in this randomized double-blind counter-balanced crossover study, and were divided into Normoxia (N) and Hypoxia-Hyperoxia (HH) trials. Subjects of the respective trials were supplied with normoxic (FiO2 = 0.21), or alternating hypoxic/hyperoxic air (FiO2 = 0.10/0.99, 5 min each) for 60 min. Thirty minutes after preconditioning, subjects performed acute bouts of RE consisting of bench press, deadlift, and squats. Each exercise included 6 sets of 10 repetitions at 75% one-repetition maximum (1RM) with 2 min rest between sets. After a 2-week washout period, subjects changed trials and completed the same study procedure after the alternate preconditioning. Muscle soreness, maximal voluntary contraction (MVC), and circulating biochemical markers were tested before preconditioning (baseline) and during recovery at 0, 24, and 48 h after exercise. Results: Acute RE significantly increased levels of muscle soreness, creatine kinase (CK) and myoglobin (Mb), and decreased levels of peak knee extension torque in the N trial. Muscle soreness, CK, and Mb levels of the HH trial were significantly lower than that of the N trial after exercise. Interestingly, interleukin-6 (IL-6) levels of the HH trial increased significantly 0 h after exercise compared to baseline and were significantly higher than that of the N trial 0 and 24 h after exercise. However, no significant differences of thiobarbituric acid reactive substances (TBARS), cortisol, testosterone, peak torque, and average power levels were found between N and HH trials during recovery. Conclusion: Our data suggest that pre-exercise treatment of alternating hypoxic/hyperoxic air could attenuate muscle damage and pain after acute RE, but has no effect on muscle strength recovery in young male athletes.

Night time resistance exercise alters muscular IL-6-related protein signaling, but not muscle growth after 10 weeks of resistance training in male rats.

The present study investigated the time-of-day effects on acute response and chronic adaptations to resistance exercise (RE) in rat skeletal muscle. Male rats were divided into Early and Late training groups and performed climbing RE during the first or last hour of the active (dark) period, respectively. The first experiment measured muscle mass and strength after a 10-week climbing training program. The second experiment examined inflammatory signaling response and satellite cell (SC) numbers following an acute bout of RE. The results showed no significant differences between rats training at early and late active periods in relative muscle weight (muscle-to-weight ratio), cross sectional area (CSA) and strength. The acute study observed increased STAT1 phosphorylation, oxidative stress (2-thiobarbituric acid reacting substances, TBARS), SCs (Pax7+), neutrophils (His48+) and macrophages (CD68+), and decreased interleukin 6 (IL-6) protein expression of skeletal muscle relative to non-exercise control after an acute bout of RE. Interestingly, higher plasma IL-6 and STAT3 phosphorylation response was observed in the late training group when compared to the early training group after an acute bout of RE. The results of this study suggest that animals can adapt to resistance training at different time-of-day, by modulating inflammatory signaling of skeletal muscle.

Seaweed Supplementation Enhances Maximal Muscular Strength and Attenuates Resistance Exercise-Induced Oxidative Stress in Rats.

We investigated the effect of chronic seaweed (Gracilaria asiatica) supplementation on maximal carrying capacity, muscle mass, and oxidative stress in rats following high-intensity resistance exercise (RE). Forty Sprague-Daley rats were equally categorized into control, exercise, seaweed, and exercise plus seaweed (ES) groups. Rats in respective groups performed RE (once per 2 days) or received seaweed (250 mg/kg bodyweight, orally) for 10 weeks. Results showed that seaweed consumption in combination with RE significantly (p < 0.05) increased maximal weight carrying capacity compared to RE alone. FHL muscle mass was significantly higher in both exercise and ES groups. Notably, high-intensity RE-induced lipid peroxidation, as evidenced by elevated thiobarbituric acid reactive substances (TBARS) in muscle, was substantially diminished (p < 0.05) by seaweed treatment. This antioxidative effect of seaweed was further represented by augmented superoxide dismutase activity and glutathione levels in seaweed groups. We noticed increased insulin concentrations and HOMA-IR, while the fasting blood glucose levels remained stable in seaweed and ES groups. Our findings conclude that seaweed in combination with RE enhanced maximal carrying strength and attenuated oxidative stress through improved antioxidant capacity. Seaweed could be a potential nutritional supplement to boost performance and to prevent exercise-induced muscle damage.

Can mesenchymal stem cell lysate reverse aging?

Recent findings regarding uses of adipose-derived mesenchymal stem cell (MSC)-lysate on weight loss and improved glucose tolerance in mice on a high-fat diet suggest an encouraging possibility of using MSC lysate for an anti-aging intervention in humans. However, weight loss and lipopenia during late life can be as life-threatening as hyperglycemia during early adulthood. For this 3-year lifelong experiment, a total of 92 rats were randomized into the vehicle-injected group (F=22; M=24) and the MSC lysate injected group (F=22, M=24). We examined longevity, spontaneous locomotor activity, and body composition in rats maintained on a normal diet and received an intermittent treatment of human adipose-derived MSC lysate (3 times a week, 11 times a month given every second month), starting at 12 months of age until natural death. In substantiating previous knowledge regarding the effects of long-term MSC lysate treatments on fat loss and insulin resistance, the present findings also highlighted a shortened average lifespan, a longer inactive time, and a greater bone loss with a relative increase of lean mass in MSC lysate rats with respect to controls. Conclusion: Our data suggest that MSC lysate treatments stimulate disparity in tissue development and produce a cachexia-like effect to decrease longevity.

Hormetic Property of Ginseng Steroids on Anti-Oxidant Status against Exercise Challenge in Rat Skeletal Muscle.

BACKGROUND: Existing literature on anti-oxidant capacity of ginseng has been inconsistent due to variance in the profile of ginseng steroids (Ginsenosides) that is because of differences in seasons and species. METHODS: We used various doses of ginseng steroids to determine its effect on oxidative stress and anti-oxidant capacity of rat skeletal muscle against exercise. RESULTS: Under non-exercise conditions, we found increased thiobarbituric acid reactive substance (TBARS) levels and decreased reduced/oxidized glutathione ratio (GSH/GSSG) in rat skeletal muscle as dose increases (p < 0.05), which indicates the pro-oxidant property of ginseng steroids at baseline. Intriguingly, exhaustive exercise-induced increased TBARS and decreased GSH/GSSG ratio were attenuated with low and medium doses of ginseng steroids (20 and 40 mg per kg), but not with high dose (120 mg per kg). At rest, anti-oxidant enzyme activities, including catalase (CAT), glutathione reductase (GR) and glutathione S-transferase (GST) were increased above vehicle-treated level, but not with the high dose, suggesting a hormetic dose-response of ginseng steroids. CONCLUSION: The results of this study provide an explanation for the inconsistent findings on anti-oxidative property among previous ginseng studies. For optimizing the anti-oxidant outcome, ginseng supplementation at high dose should be avoided.

Decreased eccentric exercise-induced macrophage infiltration in skeletal muscle after supplementation with a class of ginseng-derived steroids.

Dammarane steroids (DS) are a class of chemical compounds present in Panax ginseng. Here, we evaluated the effect of 10 weeks of DS supplementation on inflammatory modulation in the soleus muscle following eccentric exercise (EE)-induced muscle damage (downhill running). Eighty rats were randomized into 4 groups of DS supplementation (saline, 20, 60, 120 mg/kg body weight). Inflammatory markers were measured at rest and again 1 h after EE. At rest, NFκB signaling, TNF-alpha and IL-6 mRNAs, 3-nitrotyrosine, glutathione peroxidase, and GCS (glutamylcysteine synthetase) levels were significantly elevated in the skeletal muscle of DS-treated rats in a dose-dependent manner. Additionally, there were no detectable increases in the number of necrotic muscle fibers or CD68+ M1 macrophages. However, muscle strength, centronucleation, IL-10 mRNA expression, and the number of CD163+ M2 macrophages increased significantly over controls with DS treatment in rat soleus muscle. Under EE-challenged conditions, significant increases in muscle fiber necrosis, CD68+ M1 macrophage distribution, and 3-nitrotyrosine were absent in rats that received low and medium doses (20 and 60 mg/kg) of DS treatment, suggesting that DS possess anti-inflammatory action protecting against a muscle-damaging challenge. However, this protective activity was diminished when a high dose of DS (120 mg/kg) was administered, suggesting that DS possess hormetic properties. In conclusion, our study provides new evidence suggesting that DS is an ergogenic component of ginseng that potentiate inflammation at baseline but that produce anti-inflammatory effects on skeletal muscle following muscle-damaging exercise. Furthermore, high doses should be avoided in formulating ginseng-based products.

Reducing body fat with altitude hypoxia training in swimmers: role of blood perfusion to skeletal muscles.

Swimmers tend to have greater body fat than athletes from other sports. The purpose of the study was to examine changes in body composition after altitude hypoxia exposure and the role of blood distribution to the skeletal muscle in swimmers. With a constant training volume of 12.3 km/day, young male swimmers (N = 10, 14.8 ± 0.5 years) moved from sea-level to a higher altitude of 2,300 meters. Body composition was measured before and after translocation to altitude using dual-energy X-ray absorptiometry (DXA) along with 8 control male subjects who resided at sea level for the same period of time. To determine the effects of hypoxia on muscle blood perfusion, total hemoglobin concentration (THC) was traced by near-infrared spectroscopy (NIRS) in the triceps and quadriceps muscles under glucose-ingested and insulin-secreted conditions during hypoxia exposure (16% O2) after training. While no change in body composition was found in the control group, subjects who trained at altitude had unequivocally decreased fat mass (-1.7 ± 0.3 kg, -11.4%) with increased lean mass (+0.8 ± 0.2 kg, +1.5%). Arterial oxygen saturation significantly decreased with increased plasma lactate during hypoxia recovery mimicking 2,300 meters at altitude (~93% versus ~97%). Intriguingly, hypoxia resulted in elevated muscle THC, and sympathetic nervous activities occurred in parallel with greater-percent oxygen saturation in both muscle groups. In conclusion, the present study provides evidence that increased blood distribution to the skeletal muscle under postprandial condition may contribute to the reciprocally increased muscle mass and decreased body mass after a 3-week altitude exposure in swimmers.

Oral Rg1 supplementation strengthens antioxidant defense system against exercise-induced oxidative stress in rat skeletal muscles.

BACKGROUND: Previous studies reported divergent results on nutraceutical actions and free radical scavenging capability of ginseng extracts. Variations in ginsenoside profile of ginseng due to different soil and cultivating season may contribute to the inconsistency. To circumvent this drawback, we assessed the effect of major ginsenoside-Rg1 (Rg1) on skeletal muscle antioxidant defense system against exhaustive exercise-induced oxidative stress. METHODS: Forty weight-matched rats were evenly divided into control (N = 20) and Rg1 (N = 20) groups. Rg1 was orally administered at the dose of 0.1 mg/kg bodyweight per day for 10-week. After this long-term Rg1 administration, ten rats from each group performed an exhaustive swimming, and remaining rats considered as non-exercise control. Tibialis anterior (TA) muscles were surgically collected immediately after exercise along with non-exercise rats. RESULTS: Exhaustive exercise significantly (p<0.05) increased the lipid peroxidation of control group, as evidenced by elevated malondialdehyde (MDA) levels. The increased oxidative stress after exercise was also confirmed by decreased reduced glutathione to oxidized glutathione ratio (GSH/GSSG ratio) in control rats. However, these changes were completely eliminated in Rg1 group. Catalase (CAT) and glutathione peroxidase (GPx) activities were significantly (p<0.05) increased by Rg1 in non-exercise rats, while no significant change after exercise. Nevertheless, glutathione reductase (GR) and glutathione S-transferase (GST) activities were significantly increased after exercise in Rg1 group. CONCLUSIONS: This study provide compelling evidences that Rg1 supplementation can strengthen antioxidant defense system in skeletal muscle and completely attenuate the membrane lipid peroxidation induced by exhaustive exercise. Our findings suggest that Rg1 can use as a nutraceutical supplement to buffer the exhaustive exercise-induced oxidative stress.

Ginsenoside-Rg1 Protects the Liver against Exhaustive Exercise-Induced Oxidative Stress in Rats.

Despite regular exercise benefits, acute exhaustive exercise elicits oxidative damage in liver. The present study determined the hepatoprotective properties of ginsenoside-Rg1 against exhaustive exercise-induced oxidative stress in rats. Forty rats were assigned into vehicle and ginsenoside-Rg1 groups (0.1 mg/kg bodyweight). After 10-week treatment, ten rats from each group performed exhaustive swimming. Estimated oxidative damage markers, including thiobarbituric acid reactive substance (TBARS) (67%) and protein carbonyls (56%), were significantly (P < 0.01) elevated after exhaustive exercise but alleviated in ginsenoside-Rg1 pretreated rats. Furthermore, exhaustive exercise drastically decreased glutathione (GSH) content (∼79%) with concurrent decreased superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GSH-Px) activities. However, these changes were attenuated in Rg1 group. Additionally, increased xanthine oxidase (XO) activity and nitric oxide (NO) levels after exercise were also inhibited by Rg1 pretreatment. For the first time, our findings provide strong evidence that ginsenoside-Rg1 can protect the liver against exhaustive exercise-induced oxidative damage.

Specific repression of mutant K-RAS by 10-23 DNAzyme: sensitizing cancer cell to anti-cancer therapies.

Point mutations of the Ras family are frequently found in human cancers at a prevalence rate of 30%. The most common mutation K-Ras(G12V), required for tumor proliferation, survival, and metastasis due to its constitutively active GTPase activity, has provided an ideal target for cancer therapy. 10-23 DNAzyme, an oligodeoxyribonucleotide-based ribonuclease consisting of a 15-nucleotide catalytical domain flanked by two target-specific complementary arms, has been shown to effectively cleave the target mRNA at purine-pyrimidine dinucleotide. Taking advantage of this specific property, 10-23 DNAzyme was designed to cleave mRNA of K-Ras(G12V)(GGU-->GUU) at the GU dinucleotide while left the wild-type (WT) K-Ras mRNA intact. The K-Ras(G12V)-specific 10-23 DNAzyme was able to reduce K-Ras(G12V) at both mRNA and protein levels in SW480 cell carrying homozygous K-Ras(G12V). No effect was observed on the WT K-Ras in HEK cells. Although K-Ras(G12V)-specific DNAzymes alone did not inhibit proliferation of SW480 or HEK cells, pre-treatment of this DNAzyme sensitized the K-Ras(G12V) mutant cells to anti-cancer agents such as doxorubicin and radiation. These results offer a potential of using allele-specific 10-23 DNAzyme in combination with other cancer therapies to achieve better effectiveness on cancer treatment.

The use of 10-23 DNAzyme to selectively destroy the allele of mRNA with a unique purine-pyrimidine dinucleotide.

10-23 DNAzyme is an oligodeoxyribonucleotide-based ribonuclease. It consists of a 15-nt catalytic domain flanked by two target-specific complementary arms. It has been shown to cleave target mRNA effectively at purine (R)-pyrimidine (Y) dinucleotide. Taking advantage of this specific property, 10-23 DNAzyme was designed to cleave mRNA of a given allele at a unique RY dinucleotide while leaving the mRNA encoded from other alleles of the same gene intact. In this study, a p53-R249S (AGG-->AGT) mutant was tested. 10-23 DNAzyme was used to cut mutant mRNA at GT dinucleotide of codon 249. Both in vitro and in vivo studies showed that this DNAzyme could specifically cut the mutant p53 allele, leaving the wild-type unaffected. This proof-of-concept experiment provided a new way to knock down expression of a given allele with special single-base transversion.

Facilitated in vivo synthesis of ribonucleic acid and protein via T7 RNA polymerase.

Ribozyme and small interfering RNA (siRNA) now are widely used to suppress target genes bearing homologous sequences. In this study, commonly used cell lines (e.g., HEK, HeLa, H1299) were stably transfected with gene encoding T7 RNA polymerase. The cytoplasm-restricted transcription activity of T7 RNA polymerase confers a continuous and robust transcription from T7 promoter-containing oligonucleotide (ODN) template for siRNA or ribozyme and leads to 70 to 80% inhibition of the tested target genes. ODN template offers the advantages of being more stable and economical than synthetic or in vitro-transcribed siRNA or ribozyme. Compared with the use of siRNA/ribozyme-expressing plasmids, our system does not require procedures with preparations of recombinant plasmids and enrichment of transfected cells and can be applied to synthesize protein in which different levels of translation could be modulated via variations in the presence of polyA tail or internal ribosome entry site (IRES) in the T7-transcribed RNAs. The results of our current study provide a rapid and efficient system for the assay of in vivo synthesis and expression of RNAs and proteins.