Soleus Muscle Of Female Rats Research Articles

The Effect of Aerobic Exercise and Pistachio Soft Hull Extract on the Expression of the Il-6 and IL-1β Genes in the Soleus Muscle of Female Rats Fed a High-Fat Diet

Background: Obesity is considered the most important public health problem. Previous studies have confirmed that a high-fat diet (HFD) can cause the development of systemic and tissue inflammation due to the increase in pro-inflammatory markers. Objectives: This study aims to evaluate the effect of aerobic exercise and pistachio soft hull extract (PSHE) on inflammatory gene expression in the soleus muscle of rats fed a HFD. Methods: In an experimental trial, 30 female Wistar rats weighing between 180 and 200 grams were selected as subjects and randomly divided into five groups: Normal diet control, HFD control, HFD aerobic exercise, HFD-PSHE, and HFD aerobic exercise-PSHE. The aerobic exercise program consisted of four weeks of five weekly sessions of running on a treadmill at an intensity of 50 – 60% VO2max. Pistachio soft hull extract at a dose of 60 mg/kg was administered to the rats by gavage for four weeks, five times a week. Forty-eight hours after the last interventions, the rats were anesthetized, and the soleus muscle was removed to determine the expression of the IL-6 and IL-1β genes. Results: Induction of HFD significantly decreased IL-6 (P = 0.001) and increased IL-1β (P = 0.001) gene expression. IL-1β gene expression in the aerobic exercise (P = 0.001), PSHE (P = 0.003), and aerobic exercise-PSHE (P = 0.001) groups was significantly lower than in the HFD control group. Aerobic exercise (P = 0.002), PSHE (P = 0.002), and the combination of aerobic exercise and PSHE (P = 0.003) caused a significant increase in IL-6 gene expression compared to the HFD control group. Conclusions: High-fat diet promotes inflammation in skeletal muscle by increasing the expression of the IL-1β and IL-6 genes. Aerobic exercise, PSHE, and the combination of aerobic exercise and PSHE can exert their anti-inflammatory effects by reducing the expression of the IL-1β and IL-6 genes in skeletal muscle tissue.

Losartan treatment attenuates hindlimb unloading-induced atrophy in the soleus muscle of female rats via canonical TGF-\u03b2 signaling

We investigated the protective effect of losartan, an angiotensin II type 1 receptor blocker, on soleus muscle atrophy. Age-matched male and female Wistar rats were subjected to hindlimb unloading, and the soleus muscle was removed on days 1 and 7 for analysis. Females showed greater reductions in relative weight and myofiber cross-sectional area of the soleus muscle than males on day 7 post-hindlimb unloading. Losartan partially protected females against muscle atrophy. Activation of the canonical TGF-β signaling pathway, assessed via Smad2/3 phosphorylation, was lower in females following losartan treatment and associated with lower levels of protein ubiquitination after 1 (myofibril) and 7 (cytosol) days of unloading. However, no effect was observed in non-canonical TGF-β signaling (p44/p42 and p38 MAPK phosphorylation) in males or females during unloading. Our results suggest that losartan provides partial protection against hindlimb unloading-induced soleus muscle atrophy in female rats, possibly associated with decreased canonical TGF-β signaling.

Effect of hypoxia exposure on the recovery of skeletal muscle phenotype during regeneration

Hypoxia impairs the muscle fibre‐type shift from fast‐to‐slow during post‐natal development; however, this adaptation could be a consequence of the reduced voluntary physical activity associated with hypoxia exposure rather than the result of hypoxia per se. Moreover, muscle oxidative capacity could be reduced in hypoxia, particularly when hypoxia is combined with additional stress. Here, we used a model of muscle regeneration to mimic the fast‐to‐slow fibre‐type conversion observed during post‐natal development. We hypothesised that hypoxia would impair the recovery of the myosin heavy chain (MHC) profile and oxidative capacity during muscle regeneration. To test this hypothesis, the soleus muscle of female rats was injured by notexin and allowed to recover for 3, 7, 14 and 28 days under normoxia or hypobaric hypoxia (5,500 m altitude) conditions. Ambient hypoxia did not impair the recovery of the slow MHC profile during muscle regeneration. However, hypoxia moderately decreased the oxidative capacity (assessed from the activity of citrate synthase) of intact muscle and delayed its recovery in regenerated muscle. Hypoxia transiently increased in both regenerated and intact muscles the con‐ tent of phosphorylated AMPK and Pgc‐1a mRNA, two regulators involved in mitochondrial biogenesis, while it transiently increased in intact muscle the mRNA level of the mitophagic factor BNIP3.

Aged-related Differences In The Force To Stretch Soleus Muscle Of Female Rats

Aged-related Differences In The Force To Stretch Soleus Muscle Of Female Rats

Effect of hypoxia exposure on the recovery of skeletal muscle phenotype during regeneration

Hypoxia impairs the muscle fibre-type shift from fast-to-slow during post-natal development; however, this adaptation could be a consequence of the reduced voluntary physical activity associated with hypoxia exposure rather than the result of hypoxia per se. Moreover, muscle oxidative capacity could be reduced in hypoxia, particularly when hypoxia is combined with additional stress. Here, we used a model of muscle regeneration to mimic the fast-to-slow fibre-type conversion observed during post-natal development. We hypothesised that hypoxia would impair the recovery of the myosin heavy chain (MHC) profile and oxidative capacity during muscle regeneration. To test this hypothesis, the soleus muscle of female rats was injured by notexin and allowed to recover for 3, 7, 14 and 28 days under normoxia or hypobaric hypoxia (5,500 m altitude) conditions. Ambient hypoxia did not impair the recovery of the slow MHC profile during muscle regeneration. However, hypoxia moderately decreased the oxidative capacity (assessed from the activity of citrate synthase) of intact muscle and delayed its recovery in regenerated muscle. Hypoxia transiently increased in both regenerated and intact muscles the content of phosphorylated AMPK and Pgc-1α mRNA, two regulators involved in mitochondrial biogenesis, while it transiently increased in intact muscle the mRNA level of the mitophagic factor BNIP3. In conclusion, hypoxia does not act to impair the fast-to-slow MHC isoform transition during regeneration. Hypoxia alters the oxidative capacity of intact muscle and delays its recovery in regenerated muscle; however, this adaptation to hypoxia was independent of the studied regulators of mitochondrial turn-over.

Ambient hypoxia enhances the loss of muscle mass after extensive injury

Hypoxia induces a loss of skeletal muscle mass and alters myogenesis in vitro, but whether it affects muscle regeneration in vivo following injury remains to be elucidated. We hypothesized that hypoxia would impair the recovery of muscle mass during regeneration. To test this hypothesis, the soleus muscle of female rats was injured by notexin and allowed to recover for 3, 7, 14, and 28days under normoxia or hypobaric hypoxia (5,500m) conditions. Hypoxia impaired the formation and growth of new myofibers and enhanced the loss of muscle mass during the first 7days of regeneration, but did not affect the final recovery of muscle mass at 28days. The impaired regeneration under hypoxic conditions was associated with a blunted activation of mechanical target of rapamycin (mTOR) signaling as assessed by p70(S6K) and 4E-BP1 phosphorylation that was independent of Akt activation. The decrease in mTOR activity with hypoxia was consistent with the increase in AMP-activated protein kinase activity, but not related to the change in regulated in development and DNA response 1 protein content. Hypoxia increased the mRNA levels of the atrogene muscle ring finger-1 after 7days of regeneration, though muscle atrophy F box transcript levels remained unchanged. The increase in MyoD and myogenin mRNA expression with regeneration was attenuated at 7days with hypoxia. In conclusion, our results support the notion that the enhanced loss of muscle mass observed after 1week of regeneration under hypoxic conditions could mainly result from the impaired formation and growth of new fibers resulting from a reduction in protein synthesis and satellite cell activity.

Adipose-Derived Stem-Cell Treatment of Skeletal Muscle Injury

The aim of the present study was to investigate whether adipose-derived stem cells could contribute to skeletal muscle-healing. Adipose-derived stem cells of male rats were cultured and injected into the soleus muscles of female rats. Two and four weeks after injections, muscles were tested for tetanic force (50 Hz). Histological analysis was performed to evaluate muscle collagen deposition and the number of centronucleated muscle fibers. In order to track donor cells, chimerism was detected with use of real-time polymerase chain reaction targeting the male sex-determining region Y (SRY) gene. Two weeks after cell injection, tetanus strength and the number of centronucleated regenerating myofibers, as well as the number of centronucleated regenerating myofibers, were higher in the treated group than they were in the control group (mean and standard error of the mean, 79.2 ± 5.0% versus 58.3 ± 8.1%, respectively [p < 0.05]; and 145 ± 36 versus 273 ± 18 per 10³ myofibers, respectively [p < 0.05]). However, there were no significant differences at four weeks. Treatment did not decrease collagen deposition. Male gene was not detected in female host tissue at two and four weeks after engraftment by polymerase chain reaction analysis. Adipose-derived stem-cell therapy increased muscle repair and force at two weeks, but not four weeks, after injection, suggesting that adipose-derived stem-cell administration may accelerate muscle repair; however, the rapid disappearance of injected cells suggests a paracrine mechanism of action.

Ambient hypoxia enhances the muscle‐mass loss after extensive injury

The aim of this study was to examine the effect of ambient hypoxia on the main intracellular pathways involved in muscle regeneration. Left soleus muscles of female rats were degenerated by notexin injection before exposure to either normoxia (N) or ambient hypoxia (H) (10% O2) during 3, 7, 14 and 28 days (d). The expected muscle-mass loss of injured muscles was higher in H than in N rats at d3 and d7, whereas the recovery of muscle mass was similar in H and N rats at d28. The mammalian target of rapamycin (mTOR) activity, assessed from both eIF-4E binding protein (4E-BP1) and P70S6K phosphorylation, was markedly increased during the early period of regeneration, but remained two-fold lower in H than in N groups at d3. The hypoxia-induced alteration of mTOR activity, independently of Akt, was associated with an activation of AMP-activated kinase (AMPK) at d3. In contrast, REDD1, another negative regulator of mTOR, was markedly activated by H at d14 and d28 in intact muscles, but was blunted during the first days of regeneration (d3–7), independently of H. Taken together, we show for the first time, that hypoxia enhances the muscle-mass loss after extensive injury. This could be due to a specific impairment of mTOR activation during muscle regeneration, independently of Akt, at least partly related to AMPK activation, without detectable effect of REDD1. This work was supported by the Association Française contre les Myopathies (AFM).

Fibrosis and intercellular collagen connections from four weeks of muscle strains.

The effect of repeated cycles of muscle strain was studied in the soleus muscle of female rats. Muscle strains were repeated 3X/week for 1 month using two different strain protocols. Striking changes, including marked variability in fiber size, evidence of degradation and regeneration, and an expanded extracellular matrix were pronounced in the fast-stretched muscles but not in the slow-stretched muscles. However, the slow-stretched muscles did contain struts of connective tissue joining adjacent myofibers. Therefore, repeated muscle strains at high strain rates produced morphological changes similar to many myopathies, including fibrosis, whereas adaptation occurred in response to the same number of strains at slow strain rates. Such diverse tissue responses have relevance to the understanding of the mechanisms of skeletal muscle dysfunction in cumulative trauma disorders and in the design of preventive actions and treatments.