Home About us Contact
|
Home About us Contact | ||
|
|
||
Mouse Skeletal Muscle (mouse + skeletal_muscle)
Selected AbstractsNeurovascular Alignment in Adult Mouse Skeletal MusclesMICROCIRCULATION, Issue 2 2005SHAWN E. BEARDEN ABSTRACT Objective: Muscle blood flow increases with motor unit recruitment. The physical relationships between somatic motor nerves, which control muscle fiber contraction, and arterioles, which control microvascular perfusion, are unexplored. The authors tested the hypothesis that motor axons align with arterioles in adult skeletal muscle. Methods: Transgenic mice (C57BL/6 background, n = 5; 10 months of age) expressing yellow fluorescent protein in all motor nerves underwent vascular casting (Microfil). Excised epitrochlearis, gracilis, gluteus maximus, and spinotrapezius muscles were imaged at 380× and 760× and a computer-integrated tracing system (Neurolucida) was used to acquire 3-dimensional digital renderings of entire arteriolar and neural networks within each muscle. Results: Arteriolar networks were typically ,3-fold longer than neural networks. Nerves coursed with arterioles until terminating at motor endplates. Across muscles, proximity analyses revealed that , 75% of total nerve length (9.8,48.8 mm) lay within 200 ,m of the nearest arteriole (diameters of 15,60 , m). Conclusions: Somatic motor nerves and arterioles align closely within adult mammalian skeletal muscle. Understanding the signals governing neurovascular alignment may hold important clues for the advancement of tissue engineering and regeneration. [source] Muscle type-specific response of PGC-1, and oxidative enzymes during voluntary wheel running in mouse skeletal muscleACTA PHYSIOLOGICA, Issue 3-4 2006S. Ikeda Abstract Aim:, It is generally accepted that endurance exercise increases the expression of peroxisome proliferator-activated receptor , coactivator-1, (PGC-1,), which governs the expression of oxidative metabolic enzymes. A previous report demonstrated that the regulation of mitochondrial protein expression in skeletal muscles in response to cold exposure depends on muscle fibre type. Cold exposure and endurance exercise are both metabolic challenges that require adjustments in mitochondrial energy metabolism, we hypothesized that the exercise-induced increase in oxidative enzymes and PGC-1, expression is higher in fast-type than in slow-type muscle. Methods:, Female ICR mice were individually housed in cages equipped with running wheel for 1, 2, 4, 6 or 8 weeks. The soleus, plantaris (PLA) and tibialis anterior (TA) muscles were then prepared from each mouse. The expression levels of PGC-1,, mitochondrial proteins and GLUT4 were evaluated by Western blotting. Results:, The expression level of PGC-1, was increased only in the PLA muscle. Furthermore, the expression levels of all mitochondrial proteins and GLUT4 in the PLA muscle were increased. In the TA muscle, although there was no increase in PGC-1, expression, the expression levels of mitochondrial proteins and GLUT4 were increased. Conclusions:, These results suggest that muscle type-specific responses occur during endurance exercise, and that the increase in PGC-1, expression is not the only factor that promotes oxidative capacity as a result of endurance exercise. [source] Transient production of ,-smooth muscle actin by skeletal myoblasts during differentiation in culture and following intramuscular implantationCYTOSKELETON, Issue 4 2002Matthew L. Springer Abstract ,-smooth muscle actin (SMA) is typically not present in post-embryonic skeletal muscle myoblasts or skeletal muscle fibers. However, both primary myoblasts isolated from neonatal mouse muscle tissue, and C2C12, an established myoblast cell line, produced SMA in culture within hours of exposure to differentiation medium. The SMA appeared during the cells' initial elongation, persisted through differentiation and fusion into myotubes, remained abundant in early myotubes, and was occasionally observed in a striated pattern. SMA continued to be present during the initial appearance of sarcomeric actin, but disappeared shortly thereafter leaving only sarcomeric actin in contractile myotubes derived from primary myoblasts. Within one day after implantation of primary myoblasts into mouse skeletal muscle, SMA was observed in the myoblasts; but by 9 days post-implantation, no SMA was detectable in myoblasts or muscle fibers. Thus, both neonatal primary myoblasts and an established myoblast cell line appear to similarly reprise an embryonic developmental program during differentiation in culture as well as differentiation within adult mouse muscles. Cell Motil. Cytoskeleton 51:177,186, 2002. © 2002 Wiley-Liss, Inc. [source] Effect of anti-inflammatory and antioxidant drugs on the long-term repair of severely injured mouse skeletal muscleEXPERIMENTAL PHYSIOLOGY, Issue 4 2005A. Vignaud Non-steroidal anti-inflammatory drugs are frequently prescribed after skeletal muscle injury. It is not known whether this type of medication can interfere with muscle repair, although inflammatory response is thought to play an important role in this process. Tibialis anterior muscles of mice were injured by myotoxic agent (snake venom) or crushed. Then, animals were treated daily for 10,14 days with different types of non-steroidal anti-inflammatory and antioxidant drugs. The long-term repair was studied 10,42 days after injury by analysing the recovery of in situ muscle force production, size of regenerating muscle cells and expression of myosin heavy chain. Our results show that diclofenac, diferuloylmethane (curcumin), dimethylthiourea or pyrrolidine dithiocarbamate treatment did not significantly affect muscle recovery after myotoxic injury (P > 0.05). Similarly, diferuloylmethane, dimethyl sulphoxide or indomethacin administration did not markedly change muscle repair after crush injury. However, we noted that high doses (> 2 mg kg,1) of diferuloylmethane or indomethacin increased lethality and reduced muscle repair after crush injury. In conclusion, non-steroidal anti-inflammatory and antioxidant drugs did not exhibit long-term detrimental effects on muscle recovery after injury, except at lethal doses. [source] Spatial insulin signalling in isolated skeletal muscle preparationsJOURNAL OF CELLULAR BIOCHEMISTRY, Issue 5 2010Peter Sogaard Abstract During in vitro incubation in the absence or presence of insulin, glycogen depletion occurs in the inner core of the muscle specimen, concomitant with increased staining of hypoxia-induced-factor-1-alpha and caspase-3, markers of hypoxia and apoptosis, respectively. The aim of this study was to determine whether insulin is able to diffuse across the entire muscle specimen in sufficient amounts to activate signalling cascades to promote glucose uptake and glycogenesis within isolated mouse skeletal muscle. Phosphoprotein multiplex assay on lysates from muscle preparation was performed to detect phosphorylation of insulin-receptor on Tyr1146, Akt on Ser473 and glycogen-synthases-kinase-3 on Ser21/Ser9. To address the spatial resolution of insulin signalling, immunohistochemistry studies on cryosections were performed. Our results provide evidence to suggest that during the in vitro incubation, insulin sufficiently diffuses into the centre of tubular mouse muscles to promote phosphorylation of these signalling events. Interestingly, increased insulin signalling was observed in the core of the incubated muscle specimens, correlating with the location of oxidative fibres. In conclusion, insulin action was not restricted due to insufficient diffusion of the hormone during in vitro incubation in either extensor digitorum longus or soleus muscles from mouse under the specific experimental settings employed in this study. Hence, we suggest that the glycogen depleted core as earlier observed is not due to insufficient insulin action. J. Cell. Biochem. 109: 943,949, 2010. © 2010 Wiley-Liss, Inc. [source] iNOS expression requires NADPH oxidase-dependent redox signaling in microvascular endothelial cells,JOURNAL OF CELLULAR PHYSIOLOGY, Issue 1 2008Feng Wu Redox regulation of inducible nitric oxide synthase (iNOS) expression was investigated in lipopolysaccharide and interferon-, (LPS,+,IFN,)-stimulated microvascular endothelial cells from mouse skeletal muscle. Unstimulated endothelial cells produced reactive oxygen species (ROS) sensitive to inhibition of NADPH oxidase (apocynin and DPI), mitochondrial respiration (rotenone) and NOS (L-NAME). LPS,+,IFN, caused a marked increase in ROS production; this increase was abolished by inhibition of NADPH oxidase (apocynin, DPI and p47phox deficiency). LPS,+,IFN, induced substantial expression of iNOS protein. iNOS expression was prevented by the antioxidant ascorbate and by NADPH oxidase inhibition (apocynin, DPI and p47phox deficiency), but not by inhibition of mitochondrial respiration (rotenone) and xanthine oxidase (allopurinol). iNOS expression also was prevented by selective antagonists of ERK, JNK, Jak2, and NF,B activation. LPS,+,IFN, stimulated activation/phosphorylation of ERK, JNK, and Jak2 and activation/degradation of I,B, but only the activation of JNK and Jak2 was sensitive to ascorbate, apocynin and p47phox deficiency. Ascorbate, apocynin and p47phox deficiency also inhibited the LPS,+,IFN,-induced DNA binding activity of transcription factors IRF1 and AP1 but not NF,B. In conclusion, LPS,+,IFN,-induced NF,B activation is necessary for iNOS induction but is not dependent on ROS signaling. LPS,+,IFN,-stimulated NADPH oxidase activity produces ROS that activate the JNK-AP1 and Jak2-IRF1 signaling pathways required for iNOS induction. Since blocking either NF,B activation or NADPH oxidase activity is sufficient to prevent iNOS expression, they are separate targets for therapeutic interventions that aim to modulate iNOS expression in sepsis. J. Cell. Physiol. 217: 207,214, 2008. © 2008 Wiley-Liss, Inc. [source] Oxidative stress and antioxidant enzyme upregulation in SOD1-G93A mouse skeletal muscleMUSCLE AND NERVE, Issue 6 2006Douglas J. Mahoney PhD Abstract Amyotrophic lateral sclerosis (ALS) is caused by motor neuron loss in the spinal cord, but the mechanisms responsible are not known. Ubiquitous transgenic overexpression of copper/zinc superoxide dismutase (SOD1) mutations causing familial ALS (SOD1mut) leads to an ALS phenotype in mice; however, restricted expression of SOD1mut in neurons alone is not sufficient to cause this phenotype, suggesting that non-neuronal SOD1mut expression is also required for disease manifestation. Recently, several investigators have suggested that SOD1mut -mediated oxidative stress in skeletal muscle may contribute to ALS pathogenesis. The purpose of this study was to examine oxidative stress and antioxidant enzyme adaptation in 95-day-old SOD1-G93A skeletal muscle. We observed significant elevations in both malondialdehyde (22% and 31% in red and white gastrocnemius, respectively) and protein carbonyls (53% in red gastrocnemius) in SOD1-G93A mice. Copper/zinc SOD activity was higher in red and white SOD1-G93A gastrocnemius (7- and 10-fold, respectively), as was manganese SOD (4- and 5-fold, respectively) and catalase (2- and 2.5-fold, respectively). Taken together, our data demonstrate oxidative stress and compensatory antioxidant enzyme upregulation in SOD1-G93A skeletal muscle. Muscle Nerve, 2006 [source] Alterations in inorganic phosphate in mouse hindlimb muscles during limb disuse,NMR IN BIOMEDICINE, Issue 2 2008Neeti Pathare Abstract Muscle disuse induces a wide array of structural, biochemical, and neural adaptations in skeletal muscle, which can affect its function. We recently demonstrated in patients with an orthopedic injury that cast immobilization alters the resting Pi content of skeletal muscle, which may contribute to loss of specific force. The goal of this study was to determine the direct effect of disuse on the basal phosphate content in skeletal muscle in an animal model, avoiding the confounding effects of injury/surgery. 31P and 1H MRS data were acquired from the gastrocnemius muscle of young adult mice (C57BL6 female, n,=,8), at rest and during a reversible ischemia experiment, before and after 2 weeks of cast immobilization. Cast immobilization resulted in an increase in resting Pi content (75%; p,<,0.001) and the Pi to phosphocreatine (PCr) ratio (Pi/PCr; 80%, p,<,0.001). The resting concentrations of ATP, PCr and total creatine (PCr,+,creatine) and the intracellular pH were not significantly different after immobilization. During ischemia (30,min), PCr concentrations decreased to 54,±,2% and 52,±,6% of the resting values in pre-immobilized and immobilized muscles, respectively, but there were no detectable differences in the rates of Pi increase or PCr depletion (0.55,±,0.01,mM min,1 and 0.52,±,0.03,mM min,1 before and after immobilization, respectively; p,=,0.78). At the end of ischemia, immobilized muscles had a twofold higher phosphorylation potential ([ADP][Pi]/[ATP]) and intracellular buffering capacity (3.38,±,0.54 slykes vs 6.18,±,0.57 slykes). However, the rate of PCr resynthesis (kPCr) after ischemia, a measure of in vivo mitochondrial function, was significantly lower in the immobilized muscles (0.31,±,0.04,min,1) than in pre-immobilized muscles (0.43,±,0.04,min,1). In conclusion, our findings indicate that 2 weeks of cast immobilization, independent of injury-related alterations, leads to a significant increase in the resting Pi content of mouse skeletal muscle. The increase in Pi with muscle disuse has a significant effect on the cytosolic phosphorylation potential during transient ischemia and increases the intracellular buffering capacity of skeletal muscle. Copyright © 2007 John Wiley & Sons, Ltd. [source] Blocking vascular endothelial growth factor with soluble Flt-1 improves the chondrogenic potential of mouse skeletal muscle,derived stem cellsARTHRITIS & RHEUMATISM, Issue 1 2009Seiji Kubo Objective To investigate the effect of vascular endothelial growth factor (VEGF) stimulation and the effect of blocking VEGF with its antagonist, soluble Flt-1 (sFlt-1), on chondrogenesis, using muscle-derived stem cells (MDSCs) isolated from mouse skeletal muscle. Methods The direct effect of VEGF on the in vitro chondrogenic ability of mouse MDSCs was tested using a pellet culture system, followed by real-time quantitative polymerase chain reaction (PCR) and histologic analyses. Next, the effect of VEGF on chondrogenesis within the synovial joint was tested, using genetically engineered MDSCs implanted into rat osteochondral defects. In this model, MDSCs transduced with a retroviral vector to express bone morphogenetic protein 4 (BMP-4) were coimplanted with MDSCs transduced to express either VEGF or sFlt-1 (a VEGF antagonist) to provide a gain- and loss-of-function experimental design. Histologic scoring was used to compare cartilage formation among the treatment groups. Results Hyaline-like cartilage matrix production was observed in both VEGF-treated and VEGF-blocked (sFlt-1,treated) pellet cultures, but quantitative PCR revealed that sFlt-1 treatment improved the expression of chondrogenic genes in MDSCs that were stimulated to undergo chondrogenic differentiation with BMP-4 and transforming growth factor ,3 (TGF,3). In vivo testing of articular cartilage repair showed that VEGF-transduced MDSCs caused an arthritic change in the knee joint, and sFlt-1 improved the MDSC-mediated repair of articular cartilage, compared with BMP-4 alone. Conclusion Soluble Flt-1 gene therapy improved the BMP-4, and TGF,3-induced chondrogenic gene expression of MDSCs in vitro and improved the persistence of articular cartilage repair by preventing vascularization and bone invasion into the repaired articular cartilage. [source] Delivery of small interfering RNA with a synthetic collagen poly(Pro-Hyp-Gly) for gene silencing in vitro and in vivoDEVELOPMENT GROWTH & DIFFERENTIATION, Issue 8 2010Taro Adachi Silencing gene expression by small interfering RNAs (siRNAs) has become a powerful tool for the genetic analysis of many animals. However, the rapid degradation of siRNA and the limited duration of its action in vivo have called for an efficient delivery technology. Here, we describe that siRNA complexed with a synthetic collagen poly(Pro-Hyp-Gly) (SYCOL) is resistant to nucleases and is efficiently transferred into cells in vitro and in vivo, thereby allowing long-term gene silencing in vivo. We found that the SYCOL-mediated local application of siRNA targeting myostatin, coding a negative regulator of skeletal muscle growth, in mouse skeletal muscles, caused a marked increase in the muscle mass within a few weeks after application. Furthermore, in vivo administration of an anti-luciferase siRNA/SYCOL complex partially reduced luciferase expression in xenografted tumors in vivo. These results indicate a SYCOL-based non-viral delivery method could be a reliable simple approach to knockdown gene expression by RNAi in vivo as well as in vitro. [source] Localization of the membrane-anchored MMP-regulator RECK at the neuromuscular junctionsJOURNAL OF NEUROCHEMISTRY, Issue 2 2008Satoshi Kawashima Abstract Nerve apposition on nicotinic acetylcholine receptor clusters and invagination of the post-synaptic membrane (i.e. secondary fold formation) occur by embryonic day 18.5 at the neuromuscular junctions (NMJs) in mouse skeletal muscles. Finding the molecules expressed at the NMJ at this stage of development may help elucidating how the strong linkage between a nerve terminal and a muscle fiber is established. Immunohistochemical analyses indicated that the membrane-anchored matrix metalloproteinase regulator RECK was enriched at the NMJ in adult skeletal muscles. Confocal and electron microscopy revealed the localization of RECK immunoreactivity in secondary folds and subsynaptic intracellular compartments in muscles. Time course studies indicated that RECK immunoreactivity becomes associated with the NMJ in the diaphragm at around embryonic day 18.5 and thereafter. These findings, together with known properties of RECK, support the hypothesis that RECK participates in NMJ formation and/or maintenance, possibly by protecting extracellular components, such as synaptic basal laminae, from proteolytic degradation. [source] Gated dynamic 31P MRS shows reduced contractile phosphocreatine breakdown in mice deficient in cytosolic creatine kinase and adenylate kinaseNMR IN BIOMEDICINE, Issue 5 2009Hermien E. Kan Abstract We developed a new dedicated measurement protocol for dynamic 31P MRS analysis in contracting calf muscles of the mouse, using minimally invasive assessment of the contractile force combined with the acquisition of spectroscopic data gated to muscle contraction and determination of phosphocreatine (PCr) recovery rate and ATP contractile cost. This protocol was applied in a comparative study of six wild type (WT) mice and six mice deficient in cytosolic creatine kinase and adenylate kinase isoform 1 (MAK,/, mice) using 70 repeated tetanic contractions at two contractions per minute. Force levels during single contractions, and metabolite levels and tissue pH during resting conditions were similar in muscles of MAK,/, and WT mice. Strikingly, muscle relaxation after contraction was significantly delayed in MAK,/, mice, but during repeated contractions, the decrease in the force was similar in both mouse types. Gated data acquisition showed a negligible PCr breakdown in MAK,/, immediately after contraction, without a concomitant decrease in ATP or tissue pH. This protocol enabled the determination of rapid PCr changes that would otherwise go unnoticed due to intrinsic low signal-to-noise ratio (SNR) in mouse skeletal muscles combined with an assessment of the PCr recovery rate. Our results suggest that MAK,/, mice use alternative energy sources to maintain force during repeated contractions when PCr breakdown is reduced. Furthermore, the absence of large increases in adenosine diphosphate (ADP) or differences in force compared to WT mice in our low-intensity protocol indicate that creatine kinase (CK) and adenylate kinase (AK) are especially important in facilitating energy metabolism during very high energy demands. Copyright © 2009 John Wiley & Sons, Ltd. [source] | |||||||||||||