Study on Mechanism of Dendrobium officinale Kimura et Migo in Preventing and Treating Exercise-induced Muscle Damage(EIMD)in Rats

[Objectives]This study was conducted to observe the mechanism of Dendrobium officinale Kimura et Migo on gastrocnemius muscle in rats with exercise-induced muscle damage(EIMD).[Methods]The micro-injury model of skeletal muscle was established by treadmill training.Forty two SD rats were randomly divided into a control group,1,12 and 24 h exercise groups,D.officinale 2 ml+1 h exercise group,D.officinale 2 ml+12 h exercise group,and D.officinale 2 ml+24 h exercise group,with 6 rats in each group.Various D.officinale groups were given the drug once in the morning and once in the evening at a dose of 2 ml/time,a week in advance.Except for the quiet group,the samples were collected from the 1,12 and 24 h exercise groups after anesthesia following 1,12 and 24 h of exercise for the last time,respectively,and the D.officinale 2 ml+1 h exercise group,D.officinale 2 ml+12 h exercise group and D.officinale 2 ml+24 h exercise group were also sampled after anesthesia following 1,12 and 24 h of exercise for the last time,respectively.The contents of ATP,CK-MM and CK in rat serum were determined by enzyme-linked immunosorbent assay(ELISA).The histopathological changes of gastrocnemius muscle were observed by HE staining.PCR and Western-blot detection were carried out to analyze the effects of D.officinale on IGF-1 mRNA and protein expression in gastrocnemius muscle.[Results]Compared with the quiet group,the ATP contents in the serum of rats in the 1,12 and 24 h exercise groups significantly decreased(P<0.01),while the CK and CK-MM contents significantly increased(P<0.01).The expression of IGF-1 mRNA and protein in the gastrocnemius muscle tissue significantly increased(P<0.01).Compared with the 1 h exercise group,the ATP content and IGF-1 protein expression in the gastrocnemius muscle tissue of the D.officinale liquid+1 h exercise group significantly increased(P<0.05),while the CK and CK-MM contents significantly decreased(P<0.01).Compared with the 12 h exercise group,the D.officinale liquid+12 h exercise group showed a significant increase in ATP content(P<0.01),significant increases in IGF-1 mRNA and protein expression in the gastrocnemius muscle tissue(P<0.01),and significant decreases in CK and CK-MM contents(P<0.01).Compared with the 24 h exercise group,the ATP content and IGF-1 mRNA and protein expression in the gastrocnemius muscle tissue of the D.officinale liquid+24 h exercise group significantly increased(P<0.01),while the CK and CK-MM contents significantly decreased(P<0.01).From the pathological tissue morphology of the gastrocnemius muscle in rats with EIMD treated with D.officinale,it could be concluded that the gastrocnemius muscle of each exercise group was significantly damaged,and the damage was significantly alleviated after administration of D.officinale liquid.[Conclusions]The effects and mechanism of D.officinale on prevention and treatment of EIMD in rats might be related to the promotion of IGF-1 mRNA and protein expression in injured tissues by reducing ATP energy consumption,CK-MM and CK activity.

Clemastine in remyelination and protection of neurons and skeletal muscle after spinal cord injury

Spinal cord injuries affect nearly five to ten individuals per million every year. Spinal cord injury causes damage to the nerves, muscles, and the tissue surrounding the spinal cord. Depending on the severity, spinal injuries are linked to degeneration of axons and myelin, resulting in neuronal impairment and skeletal muscle weakness and atrophy. The protection of neurons and promotion of myelin regeneration during spinal cord injury is important for recovery of function following spinal cord injury. Current treatments have little to no effect on spinal cord injury and neurogenic muscle loss. Clemastine, an Food and Drug Administration-approved antihistamine drug, reduces inflammation, protects cells, promotes remyelination, and preserves myelin integrity. Recent clinical evidence suggests that clemastine can decrease the loss of axons after spinal cord injury, stimulating the differentiation of oligodendrocyte progenitor cells into mature oligodendrocytes that are capable of myelination. While clemastine can aid not only in the remyelination and preservation of myelin sheath integrity, it also protects neurons. However, its role in neurogenic muscle loss remains unclear. This review discusses the pathophysiology of spinal cord injury, and the role of clemastine in the protection of neurons, myelin, and axons as well as attenuation of skeletal muscle loss following spinal cord injury.

Screening and verification of the lncRNA-miRNA-mRNA regulatory network in muscle atrophy after spinal cord injury

Objective:To find the key targets of muscle atrophy after spinal cord injury(SCI)were excavated,to construct the lncRNA-miRNA-mRNA regulatory network based on bioinformatics analysis,and to verify the expression changes of key regulatory networks in muscle atrophy after SCI by animal experiments,so as to seek new research directions for the pathogenesis and treatment of muscle atrophy after SCI.Methods:The GSE21497 data set was downloaded from the GEO database for differential expression gene screening and WGCNA treatment.Combined with the online prediction database,key mRNAs were screened out.GO and KEGG enrichment analyses of key mRNAs were performed using the DAVID database to construct the lncRNA-miRNA-mRNA regulatory network.The key regulatory genes were selected and then verified by RT-qPCR.Results:A total of 1405 differentially expressed genes were screened,and 30 key mRNAs were predicted by the WGCNA and online database.GO and KEGG enrichment analyses showed that it was mainly enriched in the functions of neuron regeneration,protection,signal transmission,the HIF signaling pathway,PD-L1 expression and the PD-1 checkpoint pathway.Four key regulatory networks were identified(LINC00410/miR-17-5p/KCNK10,LINC00410/miR-17-5p/PCDHA3,LINC00410/miR-20b-5p/KCNK10,LINC00410/miR-20b-5p/PCDHA3).The results of RT-qPCR showed that,compared with the control group,the expression of miR-17-5p and miR-20b-5p in the observation group increased,and the expression of KCNK10 and PCDHA3 decreased.Conclusions:MiR-17-5p,miR-20b-5p,KCNK10,and PCDHA3 may play an important regulatory role in the regeneration,protection,and signal transmission of neurons,which is expected to become a new target for the diagnosis and treatment of muscle atrophy after SCI.

Single dose of intra-muscular platelet rich plasma reverses the increase in plasma iron levels in exercise-induced muscle damage:A pilot study

Background:Platelet rich plasma(PRP) therapy is widely used in enhancing the recovery of skeletal muscle from injury.However,the impact of intramuscular delivery of PRP on hematologic and biochemical responses has not been fully elucidated in exercise-induced muscle damage.The purpose of this investigation the effects of intramuscular delivery of PRP on hematologic and biochemical responses and recovery strategy muscle damage induced by high intensity muscle exercise(exercise-induced muscle damage,EIMD).Methods:Moderately active male volunteers participated in this study and were assigned to a control group(control,n = 6) and PRP administration group(PRP,n = 6).The subjects performed exercise with a load of 80% one repetition maximum(1RM) maximal voluntary contraction of the elbow flexors until point of exhaustion of the non-dominant arm was reached.The arms were treated with saline or autologous PRP post-24 h EIMD.Venous blood samples were obtained in the morning to establish a baseline value and 1–4 days post-exercise and were analyzed for serum ferritin,iron,iron binding capacity(IBC),creatinine kinase(CK),lactate dehydrogenase(LDH),aspartate aminotransferase(AST),and alanine aminotransferase(ALT).Results:The baseline levels of plasma iron,ferritin,IBC,CK,LDH,AST,and ALT were similar in both the control and PRP groups.However,24-h following exercise a significant increase in these parameters was observed in both groups between 1 and 4 days during the recovery period.Interestingly,PRP administration decreased plasma iron levels compared to the control on the second day post-exercise.Plasma IBC increased in PRP group from Days 2 to 4 post-exercise compared to the control group whilst PRP administration had no effect on plasma ferritin,CK,AST,ALT,or LDH.Conclusion:Acute exhaustive exercise increased muscle damage markers,including plasma iron,IBC,and ferritin levels,indicating muscle damage induced by exercise.PRP administration improves inflammation by reversing the increase in the iron levels post-exercise without displaying any myotoxicity and may have a role to play in the recovery of exercise-induced muscle damage.

Real-time surface electromyography in Parkinson's disease patients during exercise-induced muscle fatigue

To explore the mechanisms underlying exercise-induced local muscle fatigue in patients with idiopathic Parkinson＇s disease （PD）,we used surface electromyography to record myoelectric signals from the tibialis anterior muscle during isometric contraction-induced fatigue until exhaustion.The results revealed no significant differences between patients with idiopathic PD and healthy controls in maximum voluntary contraction of the tibialis anterior muscle.The basic characteristics of surface electromyography were also similar between the two groups.The duration of isometric contraction at 50% maximum voluntary contraction was shortened in PD patients.In addition,PD patients exhibited a stronger increase in mean square amplitude,but a weaker decrease in median frequency and mean power frequency compared with healthy controls during isometric contraction.The skeletal muscles of PD patients revealed specificity of surface electromyography findings,indicating increased fatigability compared with healthy controls.

Platelet-rich plasma for muscle injuries: A systematic review of the basic science literature

BACKGROUND Platelet-rich plasma(PRP) is an increasingly used biologic adjunct for muscle injuries, as it is thought to expedite healing. Despite its widespread use, little is known regarding the mechanisms by which PRP produces its efficacious effects in some patients.AIM To clarify the effects of PRP on muscular pathologies at the cellular and tissue levels by evaluating the basic science literature.METHODS A systematic review of PubMed/MEDLINE and EMBASE databases was performed using the Preferred Reporting Items for Systematic Reviews and MetaAnalyses(PRISMA) guidelines and checklist. Level III in vivo and in vitro studies examining PRP effects on muscles, myocytes and/or myoblasts were eligible for inclusion. Extracted data included PRP preparation methods and study results.RESULTS Twenty-three studies were included(15 in vivo, 6 in vitro, 2 in vitro/in vivo). Only one reported a complete PRP cytology(platelets, and red and white blood cell counts). Five in vitro studies reported increased cellular proliferation, four reported increased gene expression, and three reported increased cellular differentiation. Five in vivo studies reported increased gene expression, three reported superior muscle regeneration, and seven reported improved histological quality of muscular tissue.CONCLUSION The basic science literature on the use of PRP in muscle pathology demonstrates that PRP treatment confers several potentially beneficial effects on healing in comparison to controls. Future research is needed to determine optimal cytology,dosing, timing, and delivery methods of PRP for muscle pathologies.

GSK3β inhibitor promotes myelination and mitigates muscle atrophy after peripheral nerve injury

Delay of axon regeneration after peripheral nerve injury usually leads to progressive muscle atrophy and poor functional recovery. The Wnt/β-catenin signaling pathway is considered to be one of the main molecular mechanisms that lead to skeletal muscle atrophy in the elderly. We hold the hypothesis that the innervation of target muscle can be promoted by accelerating axon regeneration and decelerating muscle cell degeneration so as to improve functional recovery of skeletal muscle following peripheral nerve injury. This process may be associated with the Wnt/β-catenin signaling pathway. Our study designed in vitro cell models to simulate myelin regeneration and muscle atrophy. We investigated the effects of SB216763, a glycogen synthase kinase 3 beta inhibitor, on the two major murine cell lines RSC96 and C2C12 derived from Schwann cells and muscle satellite cells. The results showed that SB216763 stimulated the Schwann cell migra- tion and myotube contraction. Quantitative polymerase chain reaction results demonstrated that myelin related genes, myelin associated glycoprotein and cyclin-D1, muscle related gene myogenin and endplate-associated gene nicotinic acetylcholine receptors levels were stimulated by SB216763. Immunocytochemical staining revealed that the expressions of ^-catenin in the RSC96 and C2C12 cytosolic and nuclear compartments were increased in the SB216763-treated cells. These findings confirm that the glycogen synthase kinase 3 beta in- hibitor, SB216763, promoted the myelination and myotube differentiation through the Wnt/β-catenin signaling pathway and contributed to nerve remyelination and reduced denervated muscle atrophy after peripheral nerve injury.

Magnetic Resonance Imaging and Histopathological Analysis of Experimental Muscle Injuries in a Rabbit

Objective To investigate the correlation of magnetic resonance imaging （MRI） with histopathologica changes, and to evaluate T2 mapping in assessing muscle trauma in a rabbit model of muscle injury. Methods We divided 35 rabbits into seven groups that each represented a different time point after intramuscular hemorrhage and muscle injury. Hemorrhage was created by injecting autologous blood into the left legs, and muscle injury was created by scalpel incision of the biceps femoris of the right legs. At different time points, the rabbits underwent Tl-weighted imaging and T2-weighted imaging （TzWl and T2Wl） and T2 mapping. T2 relaxation times were measured, and the corresponding samples were evaluated for pathological changes. Results After 2 h, the intramuscular hemorrhage model demonstrated an increased signal intensity on both TlWl and T2Wl. Histological examination showed erythrocytes within the muscle bundle. On days 1 and 3, the MRI signals were decreased, and there were no significant changes after day 7. From 2 h to 3 days, the muscle-injury model showed a high signal on both TzWl and T2Wl. Corresponding pathological changes included rupture and edema of muscle fibers, and inflammation. The abnormal signals were reduced on day 7. After day 14, the T2Wl intensity remained high. TlWl showed no abnormal changes, but some models showed a high signal, representing fresh bleeding and fatty tissue. T2 relaxation times were significantly different between the central and marginal regions, and between the marginal and normal regions. Conclusion MRI clearly demonstrates intramuscular hemorrhage and muscle injury, which correlate well with histopathological changes. Tz mapping is useful in assessing the extent of injury.

Early electrical field stimulation prevents the loss of spinal cord anterior horn motoneurons and muscle atrophy following spinal cord injury

Our previous study revealed that early application of electrical field stimulation（EFS） with the anode at the lesion and the cathode distal to the lesion reduced injury potential, inhibited secondary injury and was neuroprotective in the dorsal corticospinal tract after spinal cord injury（SCI）. The objective of this study was to further evaluate the effect of EFS on protection of anterior horn motoneurons and their target musculature after SCI and its mechanism. Rats were randomized into three equal groups. The EFS group received EFS for 30 minutes immediately after injury at T_（10）. SCI group rats were only subjected to SCI and sham group rats were only subjected to laminectomy. Luxol fast blue staining demonstrated that spinal cord tissue in the injury center was better protected; cross-sectional area and perimeter of injured tissue were significantly smaller in the EFS group than in the SCI group. Immunofluorescence and transmission electron microscopy showed that the number of spinal cord anterior horn motoneurons was greater and the number of abnormal neurons reduced in the EFS group compared with the SCI group. Wet weight and cross-sectional area of vastus lateralis muscles were smaller in the SCI group to in the sham group. However, EFS improved muscle atrophy and behavioral examination showed that EFS significantly increased the angle in the inclined plane test and Tarlov＇s motor grading score. The above results confirm that early EFS can effectively impede spinal cord anterior horn motoneuron loss, promote motor function recovery and reduce muscle atrophy in rats after SCI.

GDNF to the rescue:GDNF delivery effects on motor neurons and nerves,and muscle re-innervation after peripheral nerve injuries

Peripheral nerve injuries commonly occur due to trauma,like a traffic accident.Peripheral nerves get severed,causing motor neuron death and potential muscle atrophy.The current golden standard to treat peripheral nerve lesions,especially lesions with large(≥3 cm)nerve gaps,is the use of a nerve autograft or reimplantation in cases where nerve root avulsions occur.If not tended early,degeneration of motor neurons and loss of axon regeneration can occur,leading to loss of function.Although surgical procedures exist,patients often do not fully recover,and quality of life deteriorates.Peripheral nerves have limited regeneration,and it is usually mediated by Schwann cells and neurotrophic factors,like glial cell line-derived neurotrophic factor,as seen in Wallerian degeneration.Glial cell line-derived neurotrophic factor is a neurotrophic factor known to promote motor neuron survival and neurite outgrowth.Glial cell line-derived neurotrophic factor is upregulated in different forms of nerve injuries like axotomy,sciatic nerve crush,and compression,thus creating great interest to explore this protein as a potential treatment for peripheral nerve injuries.Exogenous glial cell line-derived neurotrophic factor has shown positive effects in regeneration and functional recovery when applied in experimental models of peripheral nerve injuries.In this review,we discuss the mechanism of repair provided by Schwann cells and upregulation of glial cell line-derived neurotrophic factor,the latest findings on the effects of glial cell line-derived neurotrophic factor in different types of peripheral nerve injuries,delivery systems,and complementary treatments(electrical muscle stimulation and exercise).Understanding and overcoming the challenges of proper timing and glial cell line-derived neurotrophic factor delivery is paramount to creating novel treatments to tend to peripheral nerve injuries to improve patients'quality of life.

Establishment of an acute extraocular muscle injury model in cats

AIM： To describe an acute extraocular muscle injury model in cats. METHODS： Seventy-two cats were randomly divided into 6 groups（12 cats per group）. Cats＇ left lateral recti were clamped using a surgical needle holder with a clamping strength of 2（Groups A and D）, 4（Groups B and E） and 6 kg（Groups C and F）. The right lateral recti were treated as controls. On the 4^（th） and 7^（th） days, hematoxylin eosin（HE） staining, immunohistochemical staining for proliferating cell nuclear antigen（PCNA）, muscle force measurements and ocular alignment changes were performed to evaluate the extent of injuries. RESULTS： The morphological changes were graded as mild, moderate or severe by HE staining in all experiment groups. PCNA immunohistochemical staining indicated repairment of muscle fibers in the damaged area. On the 4^（th） and 7^（th） days after clamping, the injured lateral muscle exhibited an elevated threshold for electric stimulation. The muscle forces among groups 2, 4 and 6 kg injury at 4 d（Groups A, B and C） were statistically significant（P0.05）, respectively. In addition, medial deviation in ocular alignment was also present to various degrees in all groups. CONCLUSION： A cat model of acute extraocular muscle injury can be established by rectus clamping. Different clamping strengths can make different degrees of muscle injury. This model may help the future study in the acute extraocular muscle injury.

Skeletal muscle stiffness as measured by magnetic resonance elastography after chronic spinal cord injury:a cross-sectional pilot study

Skeletal muscle stiffness is altered after spinal cord injury(SCI).Assessing muscle stiffness is essential for rehabilitation and pharmaceutical interventions design after SCI.The study used magnetic resonance elastography to assess the changes in stiffness after chronic SCI compared to matched able-bodied controls and determine its association with muscle size,spasticity,and peak torque in persons with SCI.Previous studies examined the association between muscle stiffness and spasticity,however,we are unaware of other studies that examined the effects of muscle composition on stiffness after SCI.Ten participants(one female)with chronic SCI and eight(one female)matched able-bodied controls participated in this cross-sectional study.Magnetic resonance elastography was utilized to monitor stiffness derived from shear waves propagation.Modified Ashworth scale was used to evaluate spasticity scores in a blinded fashion.Peak isometric and isokinetic torques were measured using a biodex dynamometer.Stiffness values were non-significantly lower(12.5%;P=0.3)in the SCI group compared to able-bodied controls.Moreover,stiffness was positively related to vastus lateralis whole muscle cross-sectional area(CSA)(r2=0.64,P<0.005)and vastus lateralis absolute muscle CSA after accounting for intramuscular fat(r2=0.78,P<0.0007).Stiffness was also positively correlated to both isometric(r2=0.55-0.57,P<0.05)and isokinetic peak(r2=0.46-0.48,P<0.05)torques.Our results suggest that larger clinical trial is warranted to confirm the preliminary findings that muscle stiffness is altered after SCI compared to healthy controls.Stiffness appeared to be influenced by infiltration of intramuscular fat and modestly by the spasticity of the paralyzed muscles.The preliminary data indicated that the relationship between muscle stiffness and peak torque is not altered with changing the frequency of pulses or angular velocities.All study procedures were approved by the Institutional Review Board at the Hunter Holmes McGuire VA Medical Center,USA(IRB#:02314)on May 3,2017.

Sarcopenia diagnosed using masseter muscle area predictive of early mortality following severe traumatic brain injury

Traumatic brain injury（TBI）represents a global pandemic and is currently a leading cause of injury related death worldwide.Unfortunately,those who survive initial injury often suffer devastating functional,social,and economic consequences.

Research in prevention and rehabilitation of hamstring muscle strain injury

Hamstring muscle strain injury is the most common and prevalent injury in sports involving high-speed running,such as American football,Australian football,English rugby,soccer,track and field,and cricket.1Hamstring muscle strain injury also has a high recurrence rate of up to 48%.2The average practice and game time loss due to hamstring injury is between17 and 60 days,contingent on the grade of injury.2Severe hamstring muscle strain injuries,and associated recurrent inju-

Reduction of epinephrine in the lumbar spinal cord following repetitive blast-induced traumatic brain injury in rats

Traumatic brain inju ry-induced unfavorable outcomes in human patients have independently been associated with dysregulated levels of monoamines,especially epinephrine,although few preclinical studies have examined the epinephrine level in the central nervous system after traumatic brain injury.Epinephrine has been shown to regulate the activities of spinal motoneurons as well as increase the heart rate,blood pressure,and blood flow to the hindlimb muscles.Therefore,the purpose of the present study was to determine the impact of repeated blast-induced traumatic brain injury on the epinephrine levels in seve ral function-s pecific central nervous system regions in rats.Following three repeated blast injuries at 3-day intervals,the hippocampus,motor cortex,locus coeruleus,vestibular nuclei,and lumbar spinal cord were harvested at post-injury day eight and processed for epinephrine assays using a high-sensitive electrochemical detector cou pled with high-performance liquid chromatography.Our results showed that the epinephrine levels were significantly decreased in the lumbar spinal cord tissues of blast-induced traumatic brain injury animals compared to the levels detected in age-and sex-matched sham controls.In other function-specific central nervous system regions,although the epinephrine levels were slightly altered following blast-induced tra u matic brain injury,they were not statistically significant.These results suggest that blast injury-induced significant downregulation of epinephrine in the lumbar spinal cord could negatively impact the motor and cardiovascular function.This is the first repo rt to show altered epinephrine levels in the spinal cord following repetitive mild blast-induced traumatic brain injury.

Can muscle-derived stem cells serve as seed cells to repair spinal cord injury?

Muscle-derived stem cells （MDSCs） can come from a number of different sources, which are easy to isolate and culture, and are also useful in the transformation and expression of exogenous genes. Therefore, MDSCs could possibly be used for gene therapy in the treatment of neurological diseases. However, research on MDSCs has focused on identifying phenotypes and induced differentiation, with few in vivo animal experiments conducted. In this study, MDSCs were selected as seed cells and implanted into the rat spinal cord injury area. Results demonstrated that the MDSCs survived, migrated, and were distributed along the spinal nerves. Moreover, the motor function of rat lower limbs improved significantly, suggesting that MDSCs could be used as seed cells to repair spinal cord injury.

Spinal cord injury reprograms muscle fibroadipogenic progenitors to form heterotopic bones within muscles

The cells of origin of neurogenic heterotopic ossifications(NHOs), which develop frequently in the periarticular muscles following spinal cord injuries(SCIs) and traumatic brain injuries, remain unclear because skeletal muscle harbors two progenitor cell populations: satellite cells(SCs), which are myogenic, and fibroadipogenic progenitors(FAPs), which are mesenchymal. Lineage-tracing experiments using the Cre recombinase/Lox P system were performed in two mouse strains with the fluorescent protein Zs Green specifically expressed in either SCs or FAPs in skeletal muscles under the control of the Pax7 or Prrx1 gene promoter, respectively. These experiments demonstrate that following muscle injury, SCI causes the upregulation of PDGFRα expression on FAPs but not SCs and the failure of SCs to regenerate myofibers in the injured muscle, with reduced apoptosis and continued proliferation of muscle resident FAPs enabling their osteogenic differentiation into NHOs. No cells expressing Zs Green under the Prrx1 promoter were detected in the blood after injury, suggesting that the cells of origin of NHOs are locally derived from the injured muscle. We validated these findings using human NHO biopsies. PDGFRα+mesenchymal cells isolated from the muscle surrounding NHO biopsies could develop ectopic human bones when transplanted into immunocompromised mice, whereas CD56+myogenic cells had a much lower potential. Therefore, NHO is a pathology of the injured muscle in which SCI reprograms FAPs to undergo uncontrolled proliferation and differentiation into osteoblasts.

Time for a paradigm shift in the classification of muscle injuries

Muscle injuries remain one of the most common injuries in sport,yet despite this,there is little consensus on how to either effectively describe or determine the prognosis of a specific muscle injury.Numerous approaches to muscle classification and grading of medicine have been applied over the last century,but over the last decade the limitations of historic approaches have been recognized.As a consequence,in the past 10 years,clinical research groups have begun to question the historic approaches and reconsider the way muscle injuries are classified and described.Using a narrative approach,this manuscript describes several of the most recent attempts to classify and grade muscle injuries and highlights the relative strengths and weaknesses of each system.While each of the new classification and grading systems have strengths,there remains little consensus on a system that is both comprehensive and evidence based.Few of the currently identified features within the grading systems have relevance to accurately determining prognosis.

Effects of DHRS3 in C2C12 Myoblast Differentiation and Mouse Skeletal Muscle Injury

Myoblast differentiation is an essential process during skeletal muscle development.C2C12 myoblast is a commonly used experimental model to study muscle cell differentiation in vitro.Dehydrogenase/reductase(SDR family)member 3(DHRS3)is a highly conserved member in short-chain alcohol dehydrogenase/reductase superfamily and has been shown to be involved in the metabolism of retinol.Previous experimental results showed that the expression of DHRS3 increased significantly during the differentiation of myoblasts differentiation.However,the effect of DHRS3 on mouse muscle cell differentiation was unclear.The objective of current study was to determine if DHRS3 affected muscle cell differentiation,and if DHRS3 was involved in muscle regeneration.Protein expression was determined by western blot and immunofluorescence analysis.The activation and inhibition of DHRS3 increased and decreased C2C12 myoblast differentiation respectively,which indicated that DHRS3 could affect C2C12 myoblast differentiation.DHRS3 expression was significantly changed during muscle regeneration,with the regeneration of muscle injury,the expression of DHRS3 tended to increase first and then decrease.It suggested that DHRS3 might be involved in muscle regeneration.In summary,this study confirmed the involvement of DHRS3 in C2C12 myoblast differentiation and mouse skeletal muscle regeneration and provided a theoretical basis for further elucidating the molecular mechanism of muscle development.

Enhanced Satellite Cell Activity in Aging Skeletal Muscle after Manual Acupuncture-Induced Injury

Skeletal muscle injury stimulates normally quiescent resident satellite (stem) cells to re-enter the cell cycle and execute the myogenic program to restore muscle structure and function. Previously, we reported that manual acupuncture needling of the tibialis anterior (TA) (ST36 = Zusanli) muscle of young male rats produced focal injury and morphological changes that accompanied the presence of activated satellite cells (SC) 72 hours post-needling. To investigate whether aging TA muscle responds in a similar fashion to acupuncture needling, 17-month-old female rats were subjected to a single insertion and manual manipulation of an acupuncture needle. At 72 hours’ post-needling, hematoxylin staining of the TA revealed increased mononuclear cell infiltration that was indicative of localized injury. Moreover, this was accompanied by a four-fold increase in the expression of proliferating cell nuclear antigen within cells of needled tissues. Heightened immunofluorescence for MyoD was found within SC in the needled muscle, which correlated with a 6- and 10-fold increase in two MyoD isoforms (~38 and 42 kDa, respectively), when analyzed by Western blotting. An additional 56 kDa MyoD immunoreactive species was observed in both needled and control muscle of the aging rats. The present study in pre-senile female rats, in conjunction with our previous study in young male rats, suggests that muscle remodeling and restructuring after injury may constitute the initial cellular and molecular mechanisms that underlie the benefits associated with acupuncture throughout the life-span.