ECSS Paris 2023: CP-PN12
INTRODUCTION: The renin-angiotensin system (RAS) regulates cardiovascular function and oxidative stress, with ACE1/AT1R promoting vasoconstriction and ACE2/AT2R inducing vasodilation. ACE2 mediates SARS-CoV-2 entry, aided by TMPRSS2. Both are implicated in post-viral muscle fatigue, as their dysregulation after COVID-19 is linked to inflammation, oxidative stress, and metabolic dysfunction in human skeletal muscle (hSM). Exercise may restore RAS balance and protect against SM wasting. This study examined RAS signalling and TMPRSS2 changes in hSM following incremental exercise to exhaustion (IE) and post-exercise ischaemia, exploring the role of RONS, metabolite accumulation, and oxygenation. We hypothesise that RAS signalling and TMPRSS2 will be upregulated by intense exercise, with greater activation during ischaemic recovery and hypoxia conditions amplifying RONS production. METHODS: Eleven physically active men completed an IE under normoxic (Nx) and hypoxic (Hyp, PiO2: 73 mmHg) conditions. Immediately following exhaustion, one lower extremity was swiftly occluded at 300 mmHg. V. lateralis biopsies were obtained: baseline (PRE), immediately post-exercise from the occluded extremity (POST), and after 60s from both the occluded (OC1M) and non-occluded (nOC1M). Blood samples were taken from the femoral vein. Protein expression was analysed by WB. Stats: ANOVA, t-test and Pearson’s correlation. RESULTS: At POST, muscle lactate +25% only in OC1M (P<.05) while PCr -94 and -48% in OC1M and nOC1M, respectively (P<.005) regardless of PiO2. PO2 in the femoral vein was 21.1±2.0 and 10.6±2.8 mmHg at Wmax, in Nx and Hyp, respectively (P<.001). TMPRSS2 was upregulated at POST (57%), and OC1M (204%), regardless of FiO2. At nOC1M, TMPRSS2 was reduced to PRE levels (p>.05). AT2R expression was reduced at POST (20%, p<.05), maintained after 1 min of recovery, regardless of occlusion and FiO2. ACE1 and AT1R remained unchanged (p>.05). TMPRSS2 and ACE2 were correlated across conditions (r=0.48, p<.001) and with Nrf2/Keap1 ratio (r=0.83/r=0.54; both p<.001), catalase (r=0.80/r=0.48; both p<.001), pSer359 p47phox NOX2 (r=0.28, p=.01/r=0.65, p<.001, respectively). CONCLUSION: Our findings show that intense exercise and ischaemic recovery selectively modulate RAS-related protein expression in hSM. The robust upregulation of TMPRSS2 post-exercise, further enhanced by ischaemia, correlating with ACE2 and Nrf2/Keap1 ratio, suggests a link with oxidative stress and RAS adaptation. The reduction in AT2R post-exercise, independent of FiO2 and occlusion, could have reduced AT2R-mediated vasodilatory signalling. The stability of ACE1 and AT1R suggests a selective response to metabolic stress rather than a global RAS activation. These findings support the role of RONS in exercise-induced RAS remodelling, with implications for SM function, COVID-19 viral susceptibility and post-viral fatigue. PID2021-125354OB-C21/AEI/10.13039/501100011033/FEDER, EU.DEP2017-86409-C2-1-P. AGS:Catalina Ruiz postdoctoral - CUCIC-GOBCAN and ESF
Read CV Víctor Galván ÁlvarezECSS Paris 2023: CP-PN12
INTRODUCTION: Brown adipose tissue (BAT) promotes energy expenditure and browning of white adipose tissue [1]. BAT has an endocrine system and secreted “batokines” play a crucial role in regulating metabolism and identified ependymin-related protein 1 (EPDR1), C-X-C motif chemokine ligand 14 (CXCL14), fibroblast growth factor-21 (FGF-21), bone morphogenetic protein 8B (BMP8B), etc. [2]. However, the effects of habitual aerobic exercise on changes in mRNA expression of batokines in BAT remain unclear. Therefore, this study investigated whether the habitual aerobic exercise alters the mRNA expression of batokines in interscapular BAT of obese mice. METHODS: Eight-week-old apolipoprotein E (apoE) knockout (ApoE-/-) mice were used as an obese model and were randomly divided into the following two groups: sedentary control (ApoE-/- SED, n=6) group and 16-wk voluntary wheel running aerobic exercise (ApoE-/- AT, n=6) group. ApoE-/- mice of two groups were fed a high-fat diet during the experimental period. Age-matched C57BL/6J wild-type mice were fed a normal chow and were used as a healthy sedentary control group (WT-SED, n=6). Expression of EPDR1 mRNA, CXCL14 mRNA, FGF-21 mRNA, and BMP8B mRNA in the interscapular BAT (iBAT) were analyzed by using real-time RT-PCR with TaqMan probe. Protein expression levels of PGC1-α, as a marker for promoting the thermogenic function of BAT, in iBAT were analyzed by Western blotting. The effects of exercise training on mRNA expression of batokines were compared using one-way ANOVA. Statistical significance was defined as p<0.05. RESULTS: Epididymal fat mass of the ApoE-/- SED group was significantly higher compared with WT-SED group (p<0.05), and that of ApoE-/- AT group was significantly lower compared with ApoE-/- SED group (p<0.05). Protein expression levels of PGC1-α in the iBAT were significantly higher in the ApoE-/- AT group as compared with ApoE-/- SED group (p<0.05). EPDR1 mRNA levels in the iBAT were higher in the ApoE-/- AT group as compared with ApoE-/- SED group (ApoE-/-SED: 1.1 ± 0.1 vs ApoE-/- AT: 2.5 ± 0.8 arbitrary unit, p=0.047). Additionally, BMP8B mRNA levels in the iBAT were lower in the ApoE-/- AT group as compared with ApoE-/-SED group (ApoE-/- SED: 2.8 ± 0.6 vs ApoE-/- AT: 1.2 ± 0.3 arbitrary unit, p=0.011). However, no significant differences of mRNA expression levels of CXCL14 and FGF-21 in the iBAT were observed among the three groups. CONCLUSION: Habitual aerobic exercise may alter the mRNA expression levels of several batokines, including EPDR1 and BMP8B, in iBAT of obese mice. References: 1. Ziqubu K et al., Brown adipose tissue-derived metabolites and their role in regulating metabolism. Metabolism. 150:155709. 2024. 2. Pestel J et al., Adipokines in obesity and metabolic-related-diseases. Biochimie. 212:48-59. 2023.
Read CV Henry YamazakiECSS Paris 2023: CP-PN12
INTRODUCTION: Branched-chain amino acids (BCAAs); valine, leucine, and isoleucine, are catabolized as energy substrates in the skeletal muscles in order to meet high energy demands, replacing the reduced supply of glucose, during endurance exercise. A small molecule 3-hydroxyisobutyric acid (3HIB) is an intermediate of valine in the mitochondrial pathway of muscular BCAA catabolism, and a portion of 3HIB is released into the blood circulation in response to the amount of endurance exercises in humans and animals. We have presented at the last ECSS meeting that the administration of 3HIB rapidly and significantly increased blood glucose concentration in rats. Therefore, we hypothesized that 3HIB may play a physiological role in the regulation of blood glucose concentration. Present study evaluated the regulation of blood glucose level by 3HIB and its mechanism. METHODS: Male Wister rats (8 weeks of age) were intraperitoneally administered a 3HIB solution (60 mg/kg BW) and/or alpha-blocker prazosin (5 mg/kg BW), and glucose and its regulating hormone levels in serum and energy metabolites and mRNA expression in the liver were evaluated after 0, 15, and 60 min (N=7/groups). In addition, the ligand effect of 3HIB on G protein-coupled receptor 41 (GPR41), which is abundantly expressed in sympathetic ganglia, was evaluated by a GPCR ligand-binding assay. RESULTS: In rats, serum glucose and noradrenaline levels were significantly increased after 15 min of the 3HIB injection, but were returned to baseline levels after 60 min. Blood glucose level after 15 min of 3HIB was unchanged with the addition of prazosin. In the liver, malate concentration and glucose 6-phosphatase mRNA expression, which are a metabolite of 3HIB and a rate-limiting enzyme in the gluconeogenesis pathway, respectively, were significantly increased in the liver after 15 min of 3HIB injection. The GPCR ligand-binding assay confirmed that 3HIB has agonist activity for GPR41 at similar level as serum concentrations after the intraperitoneal administration of 3HIB or the endurance exercises. CONCLUSION: The effect of 3HIB excreted from the skeletal muscles to elevate blood glucose concentration is thought to be due to the gluconeogenesis in the liver using 3HIB itself as a substrate. In the activation of this hepatic gluconeogenesis, 3HIB may play a role in promoting the release of noradrenaline from the sympathetic nervous system through its agonist activity of GPR41. So, under condition of the severe energy expenditure, 3HIB, which is an intermediate catabolic metabolite of BCAA, a major amino acid in the structural proteins of skeletal muscle, may act as a metabolic signal from skeletal muscle to stimulate glucose supply from the liver.
Read CV Teruo MiyazakiECSS Paris 2023: CP-PN12