Number Of Muscle Fibers Research Articles

PECULIARITIES OF MORPHOFUNCTIONAL CHANGES OF MASTICATORY MUSCLES IN IODINE-DEFICIENT CONDITIONS

The problem of iodine deficiency is becoming increasingly important in Ukraine. According to the United Nations Children’s Fund (UNICEF), each and all regions of Ukraine suffer from “hidden hunger”. The World Health Assembly has stated that the elimination of iodine deficiency will be as much a triumph for health care system as the eradication of smallpox and poliomyelitis. The goal of this study was to establish the peculiarities of structural organization of the masticatory muscles of rats in experimentally induced iodine deficiency. The research material involved masticatory muscle of 36 white outbred male rats, which were divided into groups: group І – intact animals; group ІІ – kept in iodine deficiency condition; group III – exposed to iodine deficiency with the addition of goitriferous food. All manipulations with test animals were performed in agreement with the regulations on the protection of vertebrate animals. The methods used in the study included: biochemical, histological, histochemical, submicroscopic, morphometric and statistical research methods. It has been established that under the conditions of iodine deficiency the lumen of arterial vessels in masticatory muscles becomes narrowed, the vascular vessels become thickened due to membrane oedema. The number of hemocapillaries per unit area of muscle fibre goes down in all the studied muscles. The number of muscle fibres with intermediate succinate dehydrogenase activity decreases with the simultaneous increase in muscle fibres with low succinate dehydrogenase activity. Furthermore, the oedematous changes are the most prominent in muscle fibres with low succinate dehydrogenase activity. In conditions of iodine deficiency with the addition of goitriferous products, we can observe the progression of luminal narrowing of the artery and wall thickening in masticatory muscles where oedematous-dystrophic changes are considerably marked. There is a tendency in the growth in haemocapillaries number per 1 μm2. Histostructurally, the loss of cross striation is quite noticeable. The cross-section diameter increases, especially in muscle fibres with low succinate dehydrogenase activity and muscle fibres with high succinate dehydrogenase activity in the masticatory muscle proper of immature animals. Ultrastructurally, the oedematous-dystrophic changes of myofibrils and mitochondria were revealed. Thus, under the conditions of iodine deficient diet the lumen of arterial vessels narrows in the masticatory muscles, their wall thickens due to oedema of the membranes, which progresses in iodine deficient diet with the addition of goitriferous products. The number of hemocapillaries per unit area of muscle fibre decreases in both study groups. Changes in vascular bed lead to the redistribution of the number of muscle fibres and their significant oedema.

Dietary Antioxidant Supplementation Promotes Growth in Senegalese Sole Postlarvae.

Somatic growth is a balance between protein synthesis and degradation, and it is largely influenced by nutritional clues. Antioxidants levels play a key role in protein turnover by reducing the oxidative damage in the skeletal muscle, and hence promoting growth performance in the long-term. In the present study, Senegalese sole postlarvae (45 days after hatching, DAH) were fed with three experimental diets, a control (CTRL) and two supplemented with natural antioxidants: curcumin (CC) and grape seed (GS). Trial spanned for 25 days and growth performance, muscle cellularity and the expression of muscle growth related genes were assessed at the end of the experiment (70 DAH). The diets CC and GS significantly improved growth performance of fish compared to the CTRL diet. This enhanced growth was associated with larger muscle cross sectional area, with fish fed CC being significantly different from those fed the CTRL. Sole fed the CC diet had the highest number of muscle fibers, indicating that this diet promoted muscle hyperplastic growth. Although the mean fiber diameter did not differ significantly amongst treatments, the proportion of large-sized fibers (>25 μm) was also higher in fish fed the CC diet suggesting increased hypertrophic growth. Such differences in the phenotype were associated with a significant up-regulation of the myogenic differentiation 2 (myod2) and the myomaker (mymk) transcripts involved in myocyte differentiation and fusion, respectively, during larval development. The inclusion of grape seed extract (GS diet) resulted in a significant increase in the expression of myostatin1. These results demonstrate that both diets (CC and GS) can positively modulate muscle development and promote growth in sole postlarvae. This effect is more prominent in CC fed fish, where increased hyperplastic and hypertrophic growth of the muscle was associated with an upregulation of myod2 and mymk genes.

Skeletal muscle healing by M1-like macrophages produced by transient expression of exogenous GM-CSF

BackgroundAfter traumatic skeletal muscle injury, muscle healing is often incomplete and produces extensive fibrosis. The sequence of M1 and M2 macrophage accumulation and the duration of each subtype in the injured area may help to direct the relative extent of fibrogenesis and myogenesis during healing. We hypothesized that increasing the number of M1 macrophages early after traumatic muscle injury would produce more cellular and molecular substrates for myogenesis and fewer substrates for fibrosis, leading to better muscle healing.MethodsTo test this hypothesis, we transfected skeletal muscle with a plasmid vector to transiently express GM-CSF shortly after injury to drive the polarization of macrophages towards the M1 subset. C57BL/6 mouse tibialis anterior (TA) muscles were injured by contusion and electroporated with uP-mGM, which is a plasmid vector that transiently expresses GM-CSF. Myogenesis, angiogenesis, and fibrosis were evaluated by histology, immunohistochemistry, and RT-qPCR; subpopulations of macrophages by flow cytometry; and muscle functioning by the maximum running speed on the treadmill and the recovery of muscle mass.ResultsMuscle injury increased the number of local M1-like macrophages and decreased the number of M2-like macrophages on day 4, and uP-mGM treatment enhanced this variation. uP-mGM treatment decreased TGF-β1 protein expression on day 4, and the Sirius Red-positive area decreased from 35.93 ± 15.45% (no treatment) to 2.9% ± 6.5% (p < 0.01) on day 30. uP-mGM electroporation also increased Hgf, Hif1α, and Mtor gene expression; arteriole density; and muscle fiber number during regeneration. The improvement in the quality of the muscle tissue after treatment with uP-mGM affected the increase in the TA muscle mass and the maximum running speed on a treadmill.ConclusionCollectively, our data show that increasing the number of M1-like macrophages immediately after traumatic muscle injury promotes muscle recovery with less fibrosis, and this can be achieved by the transient expression of GM-CSF.

Influence of sex on the age-related adaptations of neuromuscular function and motor unit properties in elite masters athletes.

Masters athletes maintain high levels of activity into older age and allow an examination of the effects of aging dissociated from the effects of increased sedentary behaviour. Evidence suggests masters athletes are more successful at motor unit remodelling, the reinnervation of denervated fibres acting to preserve muscle fibre number, but little data are available in females. Here we used intramuscular electromyography to demonstrate that motor units sampled from the tibialis anterior show indications of remodelling from middle into older age and which does not differ between males and females. The age-related trajectory of motor unit discharge characteristic differs according to sex, with female athletes progressing to a slower firing pattern that was not observed in males. Our findings indicate motor unit remodelling from middle to older age occurs to a similar extent in male and female athletes, with discharge rates progressively slowing in females only. Motor unit (MU) remodelling acts to minimise loss of muscle fibres following denervation in older age, which may be more successful in masters athletes. Evidence suggests performance and neuromuscular function decline with age in this population, although the majority of studies have focused on males, with little available data on female athletes. Functional assessments of strength, balance and motor control were performed in 30 masters athletes (16 male) aged 44-83years. Intramuscular needle electrodes were used to sample individual motor unit potentials (MUPs) and near-fibre MUPs in the tibialis anterior (TA) during isometric contractions at 25% maximum voluntary contraction, and used to determine discharge characteristics (firing rate, variability) and biomarkers of peripheral MU remodelling (MUP size, complexity, stability). Multilevel mixed-effects linear regression models examined effects of age and sex. All aspects of neuromuscular function deteriorated with age (P<0.05) with no age×sex interactions, although males were stronger (P<0.001). Indicators of MU remodelling also progressively increased with age to a similar extent in both sexes (P<0.05), whilst MU firing rate progressively decreased with age in females (p=0.029), with a non-significant increase in males (p=0.092). Masters athletes exhibit age-related declines in neuromuscular function that are largely equal across males and females. Notably, they also display features of MU remodelling with advancing age, probably acting to reduce muscle fibre loss. The age trajectory of MU firing rate assessed at a single contraction level differed between sexes, which may reflect a greater tendency for females to develop a slower muscle phenotype.

Effects of Effective Microorganisms on Meat Quality, Microstructure of the Longissimus Lumborum Muscle, and Electrophoretic Protein Separation in Pigs Fed on Different Diets.

Simple SummaryPork is the most popular meat among consumers in Poland, but it can also be a source of pathogens. Therefore, there is a need to find effective prophylaxis in order to ensure that consumers have access to safe food with the desired nutritional qualities and, above all, food that is free of pathogens. In order to meet these expectations, producers use probiotics containing effective microorganisms (EMs) offered in the market. In this study the same probiotic, EM Bokashi, was used for the first time in combination with three nutritional variants with proteins of different origin.The aim of the study was to determine how effective microorganisms influence meat quality, the microstructure of the longissimus lumborum muscle, and electrophoretic protein separation. The study group consisted of 150 piglets divided into three feeding groups: C, E1, and E2. The feeding groups included C—a standard fodder blend with a full share of post-extracted soya meal; E1—a 50%/50% mix of pea and lupine/soya bean in phase I of fattening and a 75%/25% mix of pea and lupine/soya bean in phase II of fattening; and E2—a 50%/50% mix of pea and lupine/soya bean in phase I of fattening and in 100% pea and lupine in phase II of fattening. The experimental factor was the addition of the EM Carbon Bokashi probiotic to the diet (C + EM, E1 + EM, E2 + EM). Influence of the feeding system on the following parameters was also estimated. After slaughter, the meat quality, LL muscle microstructure, and electrophoretic protein separation were assessed. In the C + EM group, a lower water-holding capacity was demonstrated. Meat from pigs fed the effective microorganism additive was much harder in the E1+EM group compared to meat from pigs from the E1 group. A beneficial effect of effective microorganism was found in the E2 + EM group, where less thermal leakage from the meat was demonstrated. A beneficial effect of the feeding system on thermal leakage and loin eye area in the E2 + EM group was demonstrated. In the C + EM group, a lower total number of muscle fibers was demonstrated. The addition of effective microorganism caused an increase in the diameter of fast twitch fibers in the E1 + EM group. In the same group of pigs, effective microorganisms caused a lower proportion of fiber fission. This nutritional variant appears to be the most appropriate for proteins as well, because it led to the most favorable percentage of individual proteins after effective microorganisms supplementation in the longissimus lumborum muscle.

Elevated incubation temperature improves later-life swimming endurance in juvenile Chinook salmon, Oncorhynchus tshawytscha.

The effect of incubation and rearing temperature on muscle development and swimming endurance under a high-intensity swimming test was investigated in juvenile Chinook salmon (Oncorhynchus tshawytscha) in a hatchery experiment. After controlling for the effects of fork length (LF ) and parental identity, times to fatigue of fish were higher when fish were incubated or reared at warmer temperatures. Significant differences among combinations of pre- and post-emergence temperatures conformed to 15-15°C > 15-9°C > 9-9°C > 7-9°C > 7-7°C in 2011 when swimming tests were conducted at 300 accumulated temperature units post-emergence and 15-9°C > (7-9°C = 7-7°C) in 2012 when swimming tests were conducted at an LF of c. 40 mm. The combination of pre- and post-emergence temperatures also affected the number and size of muscle fibres, with differences among temperature treatments in mean fibre cross-sectional area persisting after controlling for LF and parental effects. Nonetheless, neither fibre number nor fibre size accounted for significant variation in swimming endurance. Thus, thermal carryover effects on swimming endurance were not mediated by thermal imprinting of muscle structure. This is the first study to test how temperature, body size and muscle structure interact to affect swimming endurance during early development in salmon.

Evaluation of Rat Muscle Structure in Pre-Menopausal Period after Regular Resistance Exercise and Taking Vitamin D and Calcium Supplements

Introduction: Menopause can change the musculoskeletal system by reducing estrogen hormone levels. The aim of this study was to evaluate the effect of regular resistance training accompanied by vitamins D and calcium supplements during pre-menopausal period on muscle tissues of Wistar rats’ postmenopausal period. Methods: In this experimental study, female Wistar rats were randomly divided into control, placebo, vitamins D, Calcium, excercise, vitamins D- Calcium, vitamins.D- excercise, Calcium - excercise, and vitamins.D‐ Calcium - excercise groups. Control and placebo groups were fed with a standard diet and sesame oil, respectively. The amount of calcium consumed was 35 mg / kg and the amount of vitamin D was 10000 IU during the two-month period, and in the resistance training groups, two months of training was performed with a ladder. Then ovariectomy was done and sample of the gastrocnemius muscle was taken and the diameter of muscle fiber, the number of muscle and adipocyte cell as well as the number of inflammatory cells were studied. The statistical analysis by means of one-way ANOVA and SPSS version 20 was performed. Results: Compared to the control group, the increase in the number of adipocyte cells were observed in the vitamin D, calcium-vitamin D, vitamin D-resistance exercise and placebo groups but it was not significantly different. Muscle fiber diameter significantly increased in all groups compared to the control group (P &lt;0.001). The number of muscle cells increased significantly in the calcium-resistance exercise group (103± 9), vitamin D-resistance exercise (105 ±6.9) and calcium-vitamin D-resistance exercise (114 ± 3.16) compared to the control group, while, there was a significant increase in inflammatory cells only in the control and placebo groups (p≤0.05). Conclusion: Regular resistance exercise accompanied with vitamin D and Calcium supplements in premenopausal period can improve muscle fiber diameter and muscle cell numbers; in addition, the process of decrease in the muscle strength and muscle inflammation during menopause will be delayed.

Infl uence of crossbreeding and level of feeding on microstructural indicators of lamb

When studying indicators that characterize the quality of meat and its nutritional value as part of the development and improvement of existing research methods, histological analysis of the tissues included in it becomes increasingly important. Histological method has been used to study the microstructure of muscle tissue (m. longissimus dorsi) and chemical composition in sheep of diff erent genotypes and reared at diff erent feeding levels. It has been found that the muscle tissue of sheep obtained from crossbreeding of breeds North Caucasus (SC) with Texel (T) has been characterized by a large amount of muscle fi bers by 5,0 and 11,3 % (P &lt; 0,05), the smaller amount by 5,7 and 18,6 % (P &lt; 0,05) in diameter, a higher “marbling” score by 5,2 and 8,3 points, and the lower content of connective tissue by 0,8 and 1,3 abs.% compared to purebreds North Caucasian and from crossbreeding North Caucasian with Poll Dorset breed (PD). Chemical analysis of meat revealed a tendency to increase the content of dry matter and fat by 1,1 and 0,1 abs. % in lamb genotype T×SC and less than the amount by 1,1 and 0,1 abs.% moisture compared to purebreds and PD×SC. Increasing the energy supply of sheep, regardless of breed affi liation, contributes to the formation by 10 % more number of muscle fi bers per unit area and the decrease in their diameter, which increases the “marbling” of lamb and increases its consumer quality. The results have been obtained indicate the feasibility of using morphometric indicators of muscle tissue in the development of criteria for assessing the quality of sheep meat productivity, intended for practical use in agriculture and the meat industry.

Low-Level Laser Therapy in Different Wavelengths on the Tibialis Anterior Muscle of Wistar Rats After Nerve Compression Injury

ObjectiveTraumatic injuries are common and may promote disruption of neuromuscular communication, triggering phenomena that lead to nerve degeneration and affect muscle function. A laser accelerates tissue recovery; however, the parameters used are varied, making it difficult to compare studies. The purpose of this study was to evaluate the effect of low-level laser therapy, at 660- and 830-nm wavelengths, on the tibialis anterior muscle of Wistar rats after sciatic nerve compression. MethodsTwenty animals were separated into 4 groups: control, sciatic nerve injury, lesion + 660-nm laser, and lesion + 830-nm laser. In the lesion groups, the right sciatic nerve was surgically exposed and compressed with hemostatic forceps for 30 seconds. After the third postoperative day, the groups with laser therapy were submitted to treatment for 2 weeks totaling 10 applications, performed directly on the surgical scar of the nerve injury. Grip strength was analyzed before and after the nerve injury and during the treatment period. The tibialis anterior muscle was processed for light microscopy, area measurement, smaller diameter, number of fibers, nuclei, and connective tissue. ResultsThe animals submitted to the injury experienced muscular atrophy and morphological changes in the number of muscle fibers and nuclei. In the connective tissue morphometry, there was a decrease in the treated groups compared with the untreated groups. ConclusionThe laser treatment at different wavelengths showed no improvement in the tibialis anterior muscle of Wistar rats within the morphological and functional aspects evaluated.

The scaffolding protein calpain-3 has multiple distributions in embryonic chick muscle cells and it is essential for the formation of muscle fibers

CAPN3 is a muscle-specific and an intrinsically disordered protein. Thus, as a scaffolding protein CAPN3 could play a role during early stages of myogenesis. To test this hypothesis, we studied the distribution and function of CAPN3 during myogenesis using embryonic chick muscle cells grown in vitro. Super-resolution microscopy showed CAPN3 distribution in (i) amorphous patches in myoblasts, (ii) a region near the nuclei of myotubes; (iii) adhesion plaques in myotubes, (iv) stress fiber-like structures in myotubes, and (v) filaments in fibroblasts. Downregulation of CAPN3 induced a decrease in the number of muscle cells and in the size of myotubes formed. These data show a diverse intracellular distribution of CAPN3, compatible with a scaffolding protein, and suggest a multitude of different interactions of CAPN3 with other partners during muscle formation.

Study on evaluation of toxicology and quality control of Yimusake tablet

Ethnopharmacological relevanceThe Yimusake tablet (YMSK-T) is a type of Xinjiang Uygur Medicine, which affects curing diseases of impotence and premature ejaculation. It has remarkable pharmacological effects that mainly involve improving the number and shape of smooth muscle cells in the corpus cavernosum and enhancing the relaxation and contraction function of corpus cavernosum smooth muscle. Aim of the studyThe YMSK-T prescription, which consists of 11 traditional herbs, has significant pharmacological effects, however the evaluation of toxicology and quality control of the preparation has not yet been reported. Therefore, in this study, we evaluated the toxicology and quality control of YMSK-T to ensure its safety and effectiveness in clinical applications. Materials and methodsMale rats were divided into three groups and were given continuous gavage administration of high, medium and low concentrations of YMSK-T. To determine hematopoietic parameters, orbital blood was collected at regular intervals. At termination of the experiment, rats were dissected for histopathological examination. According to the function of the prescription medicinal materials, seven active components were selected for content determination under the same chromatographic condition of using 0.2% aqueous phosphoric acid (solvent A) and acetonitrile (solvent B) with a 40 min post time: 0–13 min, 20% →30% B; 13–26 min, 30% →72% B; 26–38 min, 72% →92% B; 38–40 min, 92% →96% B. The column was maintained at 25 °C and the total sample injection was 10 μL. ResultsOur data showed that using a large dose (400X the dosage used in humans) of YMSK-T resulted in myocardium and liver damage, and eventually death of the rats. At sub-chronic toxicity, no significant differences were observed among indexes about relative organ weight, hematology, serum biochemistry and histopathological examination, and rats behaved normally. Our results also demonstrated that the YMSK-T dosage used was not toxic in the normal range. The linearity of each component was sufficient (correlation coefficients>0.9997). Moreover, the relative standard deviations of precision, repeatability, stability, and recovery were less than 2.0%, which showed that the method for determination of content was stable and reliable. ConclusionsYMSK-T has been found to be relatively safe in a rat model, and the method of content determination can be used for quality control of YMSK-T. Toxicology and quality control studies indicated that, the drug is safe and effective for clinical application.

Emodin ameliorates ovalbumin-induced airway remodeling in mice by suppressing airway smooth muscle cells proliferation

Increased number of airway smooth muscle cells (ASMCs) is a characteristic of airway remodeling in asthma. In this study we investigated whether emodin alleviated airway remodeling in a murine asthma model and reduced the proliferation of ASMCs in vitro. We provided in vivo evidence suggesting that intraperitoneal injection of emodin (20 mg/kg) 1 h prior to OVA challenge apparently alleviated the thickness of airway smooth muscle, the mass of alpha-smooth muscle actin (α-SMA), collagen deposition, epithelial damage, goblet cell hyperplasia, airway inflammation and airway hyperresponsiveness (AHR) in lung tissue. Meanwhile, we found that emodin suppressed the activation of the Akt pathway in lungtissue of allergic mouse models. Additionally, we found that emodin inhibited cellular proliferation and Akt activation in a dose-dependent manner in vitro. Furthermore, LY294002, an inhibitor for PI3K, abrogated serum-induced phosphorylation of Akt, and decreased the proliferation of ASMCs. These findings indicated that emodin alleviated ASMCs proliferation by inhibiting PI3K/Akt pathway in vivo and in vitro, which may provide a potential therapeutic option for airway smooth muscle remodeling in asthma.

Grafts of human adipose-derived stem cells into a biodegradable poly (acid lactic) conduit enhances sciatic nerve regeneration

Despite the regenerative potential of the Peripheral Nervous System (PNS), injuries with loss of a nerve segment make the functional recovery a challenge. This work aimed to investigate the effects of the association of biodegradable conduits of poly (lactic acid) (PLA) with human adipose-derived stem cells (hADSCs) on the regeneration of the sciatic nerve. C57BL / 6 male mice were submitted to sciatic nerve transection followed by tubulization with PLA conduit. Animals were allocated in two groups: the first received an injection of DMEM inside the conduit (DMEM) and the second received hADSCs inside it (hADSC). Sensory and motor functions were assessed by the pinprick test and electroneuromiography, respectively. To assess neuronal survival the retrograde tracer fluorogold was injected into the sciatic nerve distally to the lesion site. One week after that, animals were sacrificed, tissues harvested and processed for morphological evaluation. After eight weeks, all animals showed sensory recovery in the pinprick test and there was no significant difference between the two groups. The amplitude of the compound muscle action potential was higher in the hADSCs group. The number of myelinated nerve fibers, muscle cells and motor plates was higher in the hADSC group. There was also greater survival of sensory and motor neurons in the hADSC animals. These results suggest that the association of PLA conduit and cell therapy with hADSCs leads to a better functional and morphological recovery after sciatic nerve transection.

The role of vaginal palpation in motor learning of the pelvic floor muscles for women with stress urinary incontinence: study protocol for a randomized controlled trial

BackgroundApproximately 30 to 50% of women are unable to correctly perform pelvic floor muscle (PFM) contractions. For women to benefit from a pelvic floor muscle training (PFMT) programme for stress urinary incontinence (SUI), the awareness phase of PFMT cannot be omitted. The purpose of this study is to evaluate whether vaginal palpation together with verbal instructions about PFMs and body awareness techniques helps women with SUI learn how to correctly contract the PFMs and improve their functions.MethodsThis single-centre, double-blind randomized controlled trial with two intervention groups was designed following the standard protocol items for randomized interventional trials (SPIRIT). The results will be reported in a manner consistent with the Consolidated Standards of Reporting Trials (CONSORT) guidelines. Patients with SUI (n = 172) will be recruited. The experimental group will receive verbal instructions about PFM function and body awareness techniques together with vaginal palpation; the control group will receive similar protocol without vaginal palpation. The primary outcome includes the number of fast-twitch muscle fibres assessed by vaginal palpation and visual observation. Secondary outcomes include power and muscular endurance that will be assessed by visual observation and vaginal palpation (Oxford scale), the use of accessory muscles during the voluntary contraction of PFMs, and the self-efficacy and the expectations for the results using the self-efficacy scale of pelvic floor exercises.DiscussionThis study will determine whether vaginal palpation can help women with SUI to correctly perform PFM contractions and improve their functions.Trial registrationClinicalTrials.gov NCT 03325543. Registered on 30 November 2017. Study protocol version 1; 30 November 2020. Prospectively registered.

Rhodiola Crenulata ameliorates exhaustive exercise‑induced fatigue in mice by suppressing mitophagy in skeletal muscle

The aim of present study was to evaluate the potential effects of Rhodiola crenulata oral liquid (RCOL) on exhaustive exercise (EE)-induced fatigue in mice. Male Institute of Cancer Research mice from five treatment groups (n=10 per group) were orally administered with sterilized water for the Control and EE groups and/or RCOL at doses of 1.02, 3.03 and 6.06 ml/kg/day, once daily for 2 weeks. Anti-fatigue activity was subsequently evaluated by measuring the levels of creatine kinase (CK), lactic acid (LA), lactate dehydrogenase (LDH), malondialdehyde (MDA), superoxide dismutase (SOD), catalase (CAT) and total anti-oxidative capability (T-AOC). Histopathology was assessed using hematoxylin and eosin staining. Ultrastructures of mitochondria were observed by transmission electron microscopy. Energy supply capacity was assessed using citrate synthase (CS), succinate dehydrogenase (SDH), Na+-K+-ATPase, and liver and quadriceps glycogen content assays. Expression levels of mRNA and protein associated with mitophagy in the skeletal muscle were measured by reverse transcription-quantitative PCR and western blotting, respectively. RCOL was observed to markedly inhibit fatigue-induced oxidative stress by increasing the activities of SOD, CAT and T-AOC, whilst reducing the accumulation of LA, CK, LDH and MDA. Histological analysis of the quadriceps femoris tissue suggested increased numbers of muscle fibers in the RCOL groups compared with those in the EE group. RCOL administration was found to reverse EE-induced mitochondrial structural damage and alleviated defects inflicted onto the energy supply mechanism by increasing CS, SDH, Na+-K+-ATPase and glycogen levels. Additionally, RCOL reduced the protein expression of PTEN-induced kinase 1 (PINK1), Parkin, microtubule-associated proteins 1A/1B light chain 3, sequestosome 1 and ubiquitin, whilst lowering the gene expression of PINK1 and Parkin. Taken together, results from the present study clarified the anti-fatigue effect of RCOL, where the underlying mechanism may be associated with increased antioxidant activity, enhanced energy production and the inhibition of mitophagy by suppressing the PINK1/Parkin signaling pathway.

Monitoring muscle over three orders of magnitude: Widespread positive allometry among locomotor and body support musculature in the pectoral girdle of varanid lizards (Varanidae).

There is a functional trade-off in the design of skeletal muscle. Muscle strength depends on the number of muscle fibers in parallel, while shortening velocity and operational distance depend on fascicle length, leading to a trade-off between the maximum force a muscle can produce and its ability to change length and contract rapidly. This trade-off becomes even more pronounced as animals increase in size because muscle strength scales with area (length2 ) while body mass scales with volume (length3 ). In order to understand this muscle trade-off and how animals deal with the biomechanical consequences of size, we investigated muscle properties in the pectoral girdle of varanid lizards. Varanids are an ideal group to study the scaling of muscle properties because they retain similar body proportions and posture across five orders of magnitude in body mass and are highly active, terrestrially adapted reptiles. We measured muscle mass, physiological cross-sectional area, fascicle length, proximal and distal tendon lengths, and proximal and distal moment arms for 27 pectoral girdle muscles in 13 individuals across 8 species ranging from 64g to 40kg. Standard and phylogenetically informed reduced major axis regression was used to investigate how muscle architecture properties scale with body size. Allometric growth was widespread for muscle mass (scaling exponent >1), physiological cross-sectional area (scaling exponent >0.66), but not tendon length (scaling exponent >0.33). Positive allometry for muscle mass was universal among muscles responsible for translating the trunk forward and flexing the elbow, and nearly universal among humeral protractors and wrist flexors. Positive allometry for PCSA was also common among trunk translators and humeral protractors, though less so than muscle mass. Positive scaling for fascicle length was not widespread, but common among humeral protractors. A higher proportion of pectoral girdle muscles scaled with positive allometry than our previous work showed for the pelvic girdle, suggesting that the center of mass may move cranially with body size in varanids, or that the pectoral girdle may assume a more dominant role in locomotion in larger species. Scaling exponents for physiological cross-sectional area among muscles primarily associated with propulsion or with a dual role were generally higher than those associated primarily with support against gravity, suggesting that locomotor demands have at least an equal influence on muscle architecture as body support. Overall, these results suggest that larger varanids compensate for the increased biomechanical demands of locomotion and body support at higher body sizes by developing larger pectoral muscles with higher physiological cross-sectional areas. The isometric scaling rates for fascicle length among locomotion-oriented pectoral girdle muscles suggest that larger varanids may be forced to use shorter stride lengths, but this problem may be circumvented by increases in limb excursion afforded by the sliding coracosternal joint.

Improvement of Skeletal Muscle Regeneration by Platelet-Rich Plasma in Rats with Experimental Chronic Hyperglycemia.

Herein, the structural effect of autologous platelet-rich plasma (PRP) on posttraumatic skeletal muscle regeneration in rats with chronic hyperglycemia (CH) was tested. 130 white laboratory male rats divided into four groups (I—control; II—rats with CH; III—rats with CH and PRP treatment; and IV—rats for CH confirmation) were used for the experiment. CH was simulated by streptozotocin and nicotinic acid administration. Triceps surae muscle injury was reproduced by transverse linear incision. Autologous PRP was used in order to correct the possible negative CH effect on skeletal muscle recovery. On the 28th day after the injury, the regenerating muscle fiber and blood vessel number in the CH+PRP group were higher than those in the CH rats. However, the connective tissue area in the CH group was larger than that in the CH+PRP animals. The amount of agranulocytes in the regenerating muscle of the CH rats was lower compared to that of the CH+PRP group. The histological analysis of skeletal muscle recovery in CH+PRP animals revealed more intensive neoangiogenesis compared to that in the CH group. Herewith, the massive connective tissue development and inflammation signs were observed within the skeletal muscle of CH rats. Obtained results suggest that streptozotocin-induced CH has a negative effect on posttraumatic skeletal muscle regeneration, contributing to massive connective tissue development. The autologous PRP injection promotes muscle recovery process in rats with CH, shifting it away from fibrosis toward the complete muscular organ repair.

Skeletal muscle microvascular insulin resistance in type 2 diabetes is not improved by eight weeks of regular walking.

We aimed to examine whether individuals with type 2 diabetes (T2D) exhibit suppressed leg vascular conductance and skeletal muscle capillary perfusion in response to a hyperinsulinemic-euglycemic clamp and to test whether these two variables are positively correlated. Subsequently, we examined whether T2D-associated skeletal muscle microvascular insulin resistance, as well as overall vascular dysfunction, would be ameliorated by an 8-wk walking intervention (45 min at 60% of heart rate reserve, 5 sessions/week). We report that, relative to healthy subjects, overweight and obese individuals with T2D exhibit depressed insulin-stimulated increases in leg vascular conductance, skeletal muscle capillary perfusion, and Akt phosphorylation. Notably, we found that within individuals with T2D, those with lesser increases in leg vascular conductance in response to insulin exhibited the lowest increases in muscle capillary perfusion, suggesting that limited muscle capillary perfusion may be, in part, linked to the impaired ability of the upstream resistance vessels to dilate in response to insulin. Furthermore, we show that the 8-wk walking intervention, which did not evoke weight loss, was insufficient to ameliorate skeletal muscle microvascular insulin resistance in previously sedentary, overweight/obese subjects with T2D, despite high adherence and tolerance. However, the walking intervention did improve (P < 0.05) popliteal artery flow-mediated dilation (+4.52%) and reduced HbA1c (-0.75%). It is possible that physical activity interventions that are longer in duration, engage large muscle groups with recruitment of the maximum number of muscle fibers, and lead to a robust reduction in metabolic risk factors may be required to overhaul microvascular insulin resistance in T2D.NEW & NOTEWORTHY This report provides evidence that in sedentary subjects with type 2 diabetes diminished insulin-stimulated increases in leg vascular conductance and ensuing blunted capillary perfusion in skeletal muscle are not restorable by increased walking alone. More innovative physical activity interventions that ultimately result in a robust mitigation of metabolic risk factors may be vital for reestablishing skeletal muscle microvascular insulin sensitivity in type 2 diabetes.

Human Medial Gastrocnemius Conversion To Adipose Tissue, A Histological Analysis

There are very rare reports in the biomedical literature of entire human skeletal muscles being replaced by adipose tissue and thereby affecting lower limb function and ambulation. The causes are unknown. A fully preserved example was discovered in a Medical Anatomy course. PURPOSE: To examine the histological characteristics of a bilateral conversion of the medial gastrocnemii, presumably from skeletal muscle to adipose tissue. METHODS: Small specimens were collected for preservation, wax embedding, and histological analysis of the affected muscle, unaffected lateral-head of the muscle, nerve, and a control muscle. RESULTS: Hematoxylin and Eosin staining revealed an 88% decrease in the number of skeletal muscle fibers with a corresponding increase in the number of adipocytes. Connective tissue was similar between samples; however, the lateral gastrocnemius exhibited signs of inflammation with no necrosis. CONCLUSIONS: This is to our knowledge the first full histological analysis of a seeming conversion of the bilateral gastrocnemius medial heads into adipose tissue. The cause is unknown but could be related to the immune cell infiltration.

Satellite Cells and Markers of Muscle Regeneration during Unloading and Reloading: Effects of Treatment with Resveratrol and Curcumin.

We hypothesized that treatment with pharmacological agents known to increase sirtuin-1 activity (resveratrol and curcumin) may enhance muscle regeneration. In limb muscles of mice (C57BL/6J, 10 weeks) exposed to reloading for seven days following a seven-day period of hindlimb immobilization with/without curcumin or resveratrol treatment, progenitor muscle cell numbers (FACS), satellite cell subtypes (histology), early and late muscle regeneration markers, phenotype and morphometry, sirtuin-1 activity and content, and muscle function were assessed. Treatment with either resveratrol or curcumin in immobilized muscles elicited a significant improvement in numbers of progenitor, activated, quiescent, and total counts of muscle satellite cells, compared to non-treated animals. Treatment with either resveratrol or curcumin in reloaded muscles compared to non-treated mice induced a significant improvement in the CSA of both hybrid (curcumin) and fast-twitch fibers (resveratrol), sirtuin-1 activity (curcumin), sirtuin-1 content (resveratrol), and counts of progenitor muscle cells (resveratrol). Treatment with the pharmacological agents resveratrol and curcumin enhanced the numbers of satellite cells (muscle progenitor, quiescent, activated, and total satellite cells) in the unloaded limb muscles but not in the reloaded muscles. These findings have potential clinical implications as treatment with these phenolic compounds would predominantly be indicated during disuse muscle atrophy to enhance the muscle regeneration process.