Antonio G. Soares

Strength Training with Blood Flow Restriction Diminishes Myostatin Gene Expression

PURPOSE The aim of the study was to determine whether the similar muscle strength and hypertrophy responses observed after either low-intensity resistance exercise associated with moderate blood flow restriction or high-intensity resistance exercise are associated with similar changes in messenger RNA (mRNA) expression of selected genes involved in myostatin (MSTN) signaling. METHODS Twenty-nine physically active male subjects were divided into three groups: low-intensity (20% one-repetition maximum (1RM)) resistance training (LI) (n = 10), low-intensity resistance exercise associated with moderate blood flow restriction (LIR) (n = 10), and high-intensity (80% 1RM) resistance exercise (HI) (n = 9). All of the groups underwent an 8-wk training program. Maximal dynamic knee extension strength (1RM), quadriceps cross-sectional area (CSA), MSTN, follistatin-like related genes (follistatin (FLST), follistatin-like 3 (FLST-3)), activin IIb, growth and differentiation factor-associated serum protein 1 (GASP-1), and MAD-related protein (SMAD-7) mRNA gene expression were assessed before and after training. RESULTS Knee extension 1RM significantly increased in all groups (LI = 20.7%, LIR = 40.1%, and HI = 36.2%). CSA increased in both the LIR and HI groups (6.3% and 6.1%, respectively). MSTN mRNA expression decreased in the LIR and HI groups (45% and 41%, respectively). There were no significant changes in activin IIb (P > 0.05). FLST and FLST-3 mRNA expression increased in all groups from pre- to posttest (P < 0.001). FLST-3 expression was significantly greater in the HI when compared with the LIR and LI groups at posttest (P = 0.024 and P = 0.018, respectively). GASP-1 and SMAD-7 gene expression significantly increased in both the LIR and HI groups. CONCLUSIONS We concluded that LIR was able to induce gains in 1RM and quadriceps CSA similar to those observed after traditional HI. These responses may be related to the concomitant decrease in MSTN and increase in FLST isoforms, GASP-1, and SMAD-7 mRNA gene expression.

Thyroid hormone receptor-β-selective agonist GC-24 spares skeletal muscle type I to II fiber shift

Triiodothyronine (T3) is known to play a key role in the function of several tissues/organs via the thyroid hormone receptor isoforms alpha (TRα) and beta (TRβ). We have investigated the effects of GC-24, a novel synthetic TRβ-selective compound, on skeletal muscle fiber-type determination, cross-sectional area, and gene expression in rat skeletal muscles. For fiber typing, cross sections of soleus and extensor digitorum longus (EDL) muscles were stained for myosin ATPase activity at various pHs. Serum T3, T4, and cholesterol levels were also determined. Analysis of highly T3-responsive genes, viz., myosin heavy chain IIa (MHCIIa) and sarcoendoplasmic reticulum adenosine triphosphatase (SERCA1), was performed by quantitative real-time polymerase chain reaction. Equimolar doses of T3 and GC-24 had a similar cholesterol-lowering effect. T3, but not GC-24, decreased fiber type I and increased fiber type II abundance in soleus and EDL muscles. Conversely, in EDL, both T3 and GC-24 decreased the mean cross-sectional area of type I fibers. MHCIIa gene expression was reduced (approximately 50%) by T3 and unchanged by GC-24. SERCA1 gene expression was strongly induced by T3 (approximately 20-fold) and mildly induced by GC-24 (approximately two-fold). These results show that GC-24 does not significantly alter the composition of skeletal muscle fiber type and further strengthens the putative use of GC compounds as therapeutic agents.

Expression of genes related to myostatin signaling during rat skeletal muscle longitudinal growth.

In this study we investigated the gene expression of proteins related to myostatin (MSTN) signaling during skeletal muscle longitudinal growth. To promote muscle growth, Wistar male rats were submitted to a stretching protocol for different durations (12, 24, 48, and 96 hours). Following this protocol, soleus weight and length and sarcomere number were determined. In addition, expression levels of the genes that encode MSTN, follistatin isoforms 288 and 315 (FLST288 and FLST315), follistatin‐like 3 protein (FLST‐L3), growth and differentiation factor–associated protein‐1 (GASP‐1), activin IIB receptor (ActIIB), and SMAD‐7 were determined by real‐time polymerase chain reaction. Prolonged stretching increased soleus weight, length, and sarcomere number. In addition, MSTN gene expression was increased at 12–24 hours, followed by a decrease at 96 hours when compared with baseline values. FLST isoforms, FLST‐L3, and GASP‐1 mRNA levels increased significantly over all time‐points. ActIIB gene expression decreased quickly at 12–24 hours. SMAD‐7 mRNA levels showed a late increase at 48 hours, which peaked at 96 hours. The gene expression pattern of inhibitory proteins related to MSTN signaling suggests a strong downregulation of this pathway in response to prolonged stretching. Muscle Nerve, 2009

Cyclosporin-A does not affect skeletal muscle mass during disuse and recovery

Cyclosporin-A (CsA) is an immunosuppressive drug that acts as an inhibitor of calcineurin, a calcium phosphatase that has been suggested to play a role in skeletal muscle hypertrophy. The aim of the present study was to determine the effect of CsA administration (25 mg kg(-1) day(-1)) on skeletal muscle mass and phenotype during disuse and recovery. Male Wistar rats received vehicle (N = 8) or CsA (N = 8) during hind limb immobilization (N = 8) and recovery (N = 8). Muscle weight (dry/wet) and cross-sectional area were evaluated to verify the effect of CsA treatment on muscle mass. Muscle phenotype was assessed by histochemistry of myosin ATPase. CsA administration during immobilization and recovery did not change muscle/body weight ratio in the soleus (SOL) or plantaris (PL). Regarding muscle phenotype, we observed a consistent slow-to-fast shift in all experimental groups (immobilized only, receiving CsA only, and immobilized receiving CsA) as compared to control in both SOL and PL (P < 0.05). During recovery, no difference was observed in SOL or PL fiber type composition between the experimental recovered group and recovered group receiving CsA compared to their respective controls. Considering the muscle/body weight ratio, CsA administration does not maximize muscle mass loss induced by immobilization. Our results also indicate that CsA fails to block skeletal muscle regrowth after disuse. The present data suggest that calcineurin inhibition by CsA modulates muscle phenotype rather than muscle mass.

Hydralazine reduces leukocyte migration through different mechanisms in spontaneously hypertensive and normotensive rats

In addition to reducing blood pressure, hydralazine can reduce the production of inflammatory cytokines and reduce the expression of leukocyte adhesion molecules. Differences in leukocyte behavior and leukocyte adhesion molecule expression in spontaneously hypertensive rats (SHR) compared to normotensive rats have been reported. However, whether hydralazine can reduce leukocyte migration in vivo in hypertension and in normotension remains unknown. To address this question, male SHR and Wistar rats were treated for 15 days with hydralazine at a dose of ~3.5 mg/kg or ~14 mg/kg in their drinking water. The numbers of rollers and adherent and migrated cells were determined by direct vital microscopy, and blood pressure was assessed by tail plethysmography. In addition, following treatment with the higher dose, immunohistochemistry was used to measure the expression of intercellular adhesion molecule-1 (ICAM-1), P-selectin, and platelet-endothelial cell adhesion molecule-1 (PECAM-1) in endothelial cells, while flow cytometry was used to evaluate the expression of leukocyte CD18 and L-selectin. Hydralazine reduced leukocyte adherence and migration in SHR either at the higher, that reduced blood pressure levels, or lower dose, which did not reduce it. Reduced ICAM-1 expression might be involved in the reduced migration observed in SHR. In Wistar rats, only at the higher dose hydralazine reduced blood pressure levels and leukocyte migration. Reduced P-selectin expression might be involved. We therefore conclude that hydralazine reduces leukocyte migration by different mechanisms in SHR and Wistar rats, specifically by reducing ICAM-1 expression in the former and P-selectin expression in the latter.

Ubiquitin-ligase and deubiquitinating gene expression in stretched rat skeletal muscle

In order to gain insight into intracellular mechanisms involved in longitudinal growth of skeletal muscle, we determined gene expression of ubiquitin‐ligases (MAFbx/atrogin‐1, E3 alpha, and MuRF‐1) and deubiquitinating enzymes (UBP45, UBP69, and USP28) at different time‐points (24, 48, and 96 h) of continuous stretch of the soleus and tibialis anterior (TA) muscles. In the soleus, real‐time polymerase chain reaction (PCR) showed that MAFbx/atrogin‐1, E3 alpha, and MuRF‐1 gene expression was downregulated, peaking at 24–48 h. Gene expression of all deubiquitinating enzymes increased with continuous stretch of soleus. In the TA, gene expression of the ubiquitin‐ligases MAFbx/atrogin‐1 and MuRF‐1 was elevated, whereas expression of UBP45 and UBP69 was downregulated. Western blot analysis showed that the overall ubiquitination level decreased in the soleus and increased in the TA during stretch. These results suggest that ubiquitin‐ligases and deubiquitinating enzymes are involved in longitudinal growth induced by continuous muscle stretch. Muscle Nerve, 2007

Effects of Concurrent Strength and Endurance Training on Genes Related to Myostatin Signaling Pathway and Muscle Fiber Responses

Abstract De Souza, EO, Tricoli, V, Aoki, MS, Roschel, H, Brum PC, Bacurau, AVN, Silva-Batista, C, Wilson, JM, Neves, M Jr, Soares, AG, Ugrinowitsch, C. Effects of concurrent strength and endurance training on genes related to myostatin signaling pathway and muscle fiber responses. J Strength Cond Res 28(11): 3220–3228, 2014—Concurrent training (CT) seems to impair training-induced muscle hypertrophy. This study compared the effects of CT, strength training (ST) and interval training (IT) on the muscle fiber cross-sectional area (CSA) response, and on the expression of selected genes involved in the myostatin (MSTN) signaling mRNA levels. Thirty-seven physically active men were randomly divided into 4 groups: CT (n = 11), ST (n = 11), IT (n = 8), and control group (C) (n = 7) and underwent an 8-week training period. Vastus lateralis biopsy muscle samples were obtained at baseline and 48 hours after the last training session. Muscle fiber CSA, selected genes expression, and maximum dynamic ST (1 repetition maximum) were evaluated before and after training. Type IIa and type I muscle fiber CSA increased from pre- to posttest only in the ST group (17.08 and 17.9%, respectively). The SMAD-7 gene expression significantly increased at the posttest in the ST (53.9%) and CT groups (39.3%). The MSTN and its regulatory genes ActIIb, FLST-3, FOXO-3a, and GASP-1 mRNA levels remained unchanged across time and groups. One repetition maximum increased from pre- to posttest in both the ST and CT groups (ST = 18.5%; CT = 17.6%). Our findings are suggestive that MSTN and their regulatory genes at transcript level cannot differentiate muscle fiber CSA responses between CT and ST regimens in humans.

Elucidating the role of oxidative stress in the therapeutic effect of rutin on experimental acute pancreatitis

Abstract Introduction: Acute pancreatitis (AP) may be severe and cause hospitalization or death, and the available treatment is insufficient to control pancreatic inflammation and pain. Rutin is a natural flavonoid with the potential to treat AP via anti-inflammatory, antinociceptive, and antioxidant activities. Aim: This study investigated the beneficial effects of rutin on experimental AP induced by l-arginine administration in mice. Methods: The l-arginine-induced AP model was used in Swiss mice (n = 6–8). Mice submitted to AP induction were treated with rutin (37.5, 75, or 150 mg kg−1, p.o.) or vehicle (saline) after 24, 36, 48, and 60 h of AP induction. Abdominal hyperalgesia, serum enzymes, interleukin (IL)-6 levels, pancreatic inflammatory parameters, malondialdehyde (MDA) levels, antioxidant enzyme activities, and 3-nitrotyrosine contents were measured 72 h after induction. Results: Mice submitted to l-arginine injections developed abdominal hyperalgesia and increased serum amylase, lipase, C-reactive protein and IL-6 concentrations; and increased pancreatic myeloperoxidase activity, edema index, MDA, and 3-nitrotyrosine contents. A marked decrease in catalase activity was observed in the pancreas without alterations of superoxide dismutase (SOD) activity compared with the control group. Rutin treatment significantly impaired all the parameters that were altered by AP induction, but increased catalase and SOD activities in the pancreas compared with the vehicle-treated group. Conclusion: Rutin treatment exerted a protective effect on l-arginine-induced AP by mechanisms involving the reduction of oxidative stress, which suggests that this flavonoid has a potential for future approaches designed for the management of AP.

Protective effects of exogenous and endogenous hydrogen sulfide in mast cell-mediated pruritus and cutaneous acute inflammation in mice

Graphical abstract Figure. No caption available. ABSTRACT The recently described ‘gasomediator’ hydrogen sulfide (H2S) has been involved in pain mechanisms, but its effect on pruritus, a sensory modality that similarly to pain acts as a protective mechanism, is poorly known and controversial. The effects of the slow‐releasing (GYY4137) and spontaneous H2S donors (Na2S and Lawessons reagent, LR) were evaluated in histamine and compound 48/80 (C48/80)‐dependent dorsal skin pruritus and inflammation in male BALB/c mice. Animals were intradermally (i.d.) injected with C48/80 (3 &mgr;g/site) or histamine (1 &mgr;mol/site) alone or co‐injected with Na2S, LR or GYY4137 (within the 0.3–100 nmol range). The involvement of endogenous H2S and KATP channel‐dependent mechanism were also evaluated. Pruritus was assessed by the number of scratching bouts, whilst skin inflammation was evaluated by the extravascular accumulation of intravenously injected 125I‐albumin (plasma extravasation) and myeloperoxidase (MPO) activity (neutrophil recruitment). Histamine or C48/80 significantly evoked itching behavior paralleled by plasma extravasation and increased MPO activity. Na2S and LR significantly ameliorated histamine or C48/80‐induced pruritus and inflammation, although these effects were less pronounced or absent with GYY4137. Inhibition of endogenous H2S synthesis increased both Tyrode and C48/80‐induced responses in the skin, whereas the blockade of KATP channels by glibenclamide did not. H2S‐releasing donors significantly attenuate C48/80‐induced mast cell degranulation either in vivo or in vitro. We provide first evidences that H2S donors confer protective effect against histamine‐mediated acute pruritus and cutaneous inflammation. These effects can be mediated, at least in part, by stabilizing mast cells, known to contain multiple mediators and to be primary initiators of allergic processes, thus making of H2S donors a potential alternative/complementary therapy for treating inflammatory allergic skin diseases and related pruritus.

Effects of active recovery on autonomic and haemodynamic responses after aerobic exercise

The aim of this study was to examine the effect of active recovery on autonomic and haemodynamic responses after exercise in healthy adults. Nineteen healthy young male individuals underwent two experimental sessions: exercise with active recovery (AR) and exercise with passive recovery (PR). The exercise sessions comprised three phases: warm‐up (5 min), exercise phase (cycle ergometer, 30 min, intensity between 60 and 70% of the heart rate reserve) and recovery (5 min). In the AR, the subjects remained cycling in the recovery phase at intensity between 30% and 35% of heart rate reserve, while in the PR, the subjects stopped the exercise after finishing the exercise phase. Blood pressure and heart rate were measured before and over the 30 min after the interventions. There were no differences for systolic and diastolic blood pressures, heart rate and rate pressure product between active and passive recovery sessions. Also, all heart rate variability parameters changed similarly after exercise with passive or active recovery sessions. In summary, exercise with active recovery does not affect the autonomic and haemodynamic responses after moderate‐intensity aerobic exercise in healthy young male individuals.