scholarly journals UPTAKE OF EXOGENOUS HORSERADISH PEROXIDASE BY COATED VESICLES IN MOUSE NEUROMUSCULAR JUNCTIONS

1969 ◽  
Vol 17 (3) ◽  
pp. 161-170 ◽  
Author(s):  
SUMNER I. ZACKS ◽  
ATUSHI SAITO
Keyword(s):  
Skeletal Muscle ◽  
Horseradish Peroxidase ◽  
Synaptic Vesicles ◽  
Intramuscular Injection ◽  
Neuromuscular Junctions ◽  
Neuromuscular Function ◽  
Coated Vesicles ◽  
Intramuscular Nerves ◽  
Pinocytotic Vesicles ◽  
Intercellular Clefts

Following intramuscular injection of horseradish peroxidase into mouse skeletal muscle adjacent to areas of innervation, rapid uptake of the label was observed by coated but not synaptic vesicles. The tracer was also found in Schwann cells, external mesaxons and within peripheral myelin lamellae, but never in axoplasm of intramuscular nerves proximal to the injection site. The data suggest that the tracer is taken up by the coated vesicles and may be rapidly discharged into the synaptic clefts from which it is cleared by a combination of phagocytic activity and absorption via pinocytotic vesicles and intercellular clefts of adjacent capillaries or, more probably, enzyme activity is lost within the coated vesicles. The significance of these observations as related to neuromuscular function is discussed.

scholarly journals Degeneration and Regeneration of Murine Skeletal Neuromuscular Junctions after Intramuscular Injection with a Sublethal Dose of Clostridium sordellii Lethal Toxin

2004 ◽  
Vol 72 (6) ◽  
pp. 3120-3128 ◽  
Author(s):  
Julien Barbier ◽  
Michel R. Popoff ◽  
Jordi Molgó
Keyword(s):  
Skeletal Muscle ◽  
Intramuscular Injection ◽  
Neuromuscular Junctions ◽  
Muscle Fibers ◽  
Small Gtpases ◽  
Lethal Toxin ◽  
Sublethal Dose ◽  
Partial Recovery ◽  
Clostridium Sordellii ◽  
Skeletal Muscle Fibers

ABSTRACT Clostridium sordellii lethal toxin (LT), a 250-kDa protein which is the bacteria's major virulence factor, belongs to a family of large clostridial cytotoxins which glucosylate small GTP-binding proteins. Here, we report the results of our ex vivo analysis of the structure and function of skeletal neuromuscular tissue obtained from mice at various times after intramuscular injection of a sublethal dose of LT (0.25 ng/g of body wt). The toxin caused, within 24 h, pronounced localized edema, inflammation, myofibril disassembly, and degeneration of skeletal muscle fibers in the injected area, and it glucosylated the muscle tissue's small GTPases. Regeneration of the damaged fibers was evident 6 to 9 days postinjury and was completed by 60 days. The expression of dystrophin, laminin, and fast and neonatal myosin in regenerating fibers, detected by immunofluorescence microscopy, confirmed that LT does not impair the high regenerative capacity of murine skeletal muscle fibers. Functional studies revealed that LT affects muscle contractility and neuromuscular transmission. However, partial recovery of nerve-evoked muscle twitches and tetanic contractions was observed by day 15 postinjection, and extensive remodeling of the neuromuscular junction's nerve terminals and clusters of muscle acetylcholine receptors was still evident 30 days postinjection. In conclusion, to the best of our knowledge, this is the first report to characterize the degeneration and regeneration of skeletal neuromuscular tissue after in vivo exposure to a large clostridial cytotoxin. In addition, our data may provide an explanation for the severe neuromuscular alterations accompanying wound infections caused by C. sordellii.

scholarly journals Acetylcholine receptors in regenerating muscle accumulate at original synaptic sites in the absence of the nerve.

1979 ◽  
Vol 82 (2) ◽  
pp. 412-425 ◽  
Author(s):  
S J Burden ◽  
P B Sargent ◽  
U J McMahan
Keyword(s):  
Skeletal Muscle ◽  
Horseradish Peroxidase ◽  
Basal Lamina ◽  
Acetylcholine Receptors ◽  
Structural Organization ◽  
Neuromuscular Junctions ◽  
Muscle Fibers ◽  
Nerve Terminals ◽  
Alpha Bungarotoxin

We examined the role of nerve terminals in organizing acetylcholine receptors on regenerating skeletal-muscle fibers. When muscle fibers are damaged, they degenerate and are phagocytized, but their basal lamina sheaths survive. New myofibers form within the original basal lamina sheaths, and they become innervated precisely at the original synaptic sites on the sheaths. After denervating and damaging muscle, we allowed myofibers to regenerate but deliberately prevented reinnervation. The distribution of acetylcholine receptors on regenerating myofibers was determined by histological methods, using [125I] alpha-bungarotoxin or horseradish peroxidase-alpha-bungarotoxin; original synaptic sites on the basal lamina sheaths were marked by cholinesterase stain. By one month after damage to the muscle, the new myofibers have accumulations of acetylcholine receptors that are selectively localized to the original synaptic sites. The density of the receptors at these sites is the same as at normal neuromuscular junctions. Folds in the myofiber surface resembling junctional folds at normal neuromuscular junctions also occur at original synaptic sites in the absence of nerve terminals. Our results demonstrate that the biochemical and structural organization of the subsynaptic membrane in regenerating muscle is directed by structures that remain at synaptic sites after removal of the nerve.

scholarly journals Early morphological remodeling of neuromuscular junction in a murine model of diabetes

2000 ◽  
Vol 89 (6) ◽  
pp. 2235-2240 ◽  
Author(s):  
M. A. Fahim ◽  
M. Y. Hasan ◽  
W. B. Alshuaib
Keyword(s):  
Skeletal Muscle ◽  
Membrane Potential ◽  
Time Course ◽  
Neuromuscular Junctions ◽  
Muscle Membrane ◽  
Resting Membrane Potential ◽  
End Plate ◽  
Intramuscular Nerves ◽  
Skeletal Muscle Weakness ◽  
C57bl Mice

Although skeletal muscle weakness is documented in diabetes, the time course for its development is not established. The present study examined the dorsiflexor muscle from animals that had been diabetic for 2 wk. Adult male c57BL mice were injected once with streptozotocin (STZ) to induce diabetes (60 mg/kg ip). Two weeks later, resting membrane potential and miniature end-plate potentials were recorded, and electron microscopy was utilized for ultrastructural evaluations. After STZ-induced diabetes, both resting membrane potential and miniature end-plate potentials were reduced. Nerve terminals showed less synaptic vesicles and had degenerated mitochondria. Furthermore, in the intramuscular nerves, disorganization of microtubules and neurofilaments was evidenced. Myelin-like figures were present in intramuscular nerves, neuromuscular junctions, and muscle fibers. At the muscle level, mitochondria were swollen, with disorganization of their cristae, disruption of T tubules, and myofibers with more deposition of glycogen granules. The present results revealed early STZ-induced nerve and muscle alterations. Observed ultrastructural modifications resemble those of motoneuron disorders and aging processes. These changes are possibly related to alterations in Ca2+ mobilization across muscle membrane. Other mechanisms such as free radical-mediated actions may also be implicated in STZ-induced effects on skeletal muscle.

Effect of Experimentally Induced Chronic Kidney disease on Skeletal, Cardiac and Smooth Muscle fibers of albino rat

QJM ◽  
2021 ◽  
Vol 114 (Supplement_1) ◽  
Author(s):  
Ghada Lotfy ◽  
Amel Soliman ◽  
Nevine Bahaa ◽  
Mohammed Hegazi
Keyword(s):  
Skeletal Muscle ◽  
Chronic Kidney Disease ◽  
Smooth Muscle ◽  
Kidney Disease ◽  
Intramuscular Injection ◽  
Muscle Fibers ◽  
Lateral Wall ◽  
Control Group ◽  
Once Daily ◽  
Group Ii

Abstract Background Chronic kidney disease (CKD), or chronic renal failure (CRF) as it was historically termed, includes all degrees of decreased renal function, starting from mild, and moderate, to severe chronic kidney failure. Skeletal muscle atrophy frequently complicates the course of CKD and is associated with excess morbidity and mortality. Cardiovascular diseases have been reported to be the leading causes of death in CKD patients. Chronic Kidney Disease was also reported to be associated with an increased incidence of acid-related gastrointestinal disorders. Aim of the work The aim of this study was to investigate the effect of chronic kidney disease experimentally induced by gentamicin intramuscular injection on the histological structure of gastrocnemius skeletal muscle, left ventricular cardiac muscle and smooth muscle fibers of lower esophagus. Materials and methods Twenty male adult Wistar albino rats were randomly and equally divided into two groups. Group I (control group) received physiological saline intramuscular injection, once daily for 28 consecutive days, in a dose equivalent to that taken in group II. Group II (Gentamicin-treated group) were given Gentamicin intramuscular injection for induction of CKD. Gentamicin was given as Gentamycin sulfate, 40 mg/ml (Sandoz, Switzerland), once daily, in a dose of 80 mg/kg/day for 28 days to induce CKD. After 28 days of the first injection of gentamicin, rats were anaesthetized and blood samples were collected to measure the level of serum urea and creatinine. The left kidneys, the middle third of left gastrocnemius muscle, the lateral wall of left ventricle (LV) and the gastroesophageal junction of all rats of both groups (I and II) were processed for light microscopic study. The middle third of left gastrocnemius muscle, the lateral wall of left ventricle (LV) were further processed for transmission electron microscopic study. Histomorphometrical and statistical analysis were also done. Results The LM examination revealed moderate obliteration of glomeruli, dilatation in some renal tubules and collapse in others, mainly in distal convoluted tubules, with significant fibrosis of renal parenchyma. Serum urea and creatinine levels were increased significantly. The skeletal muscle fibers of the rats in group II (CKD) showed focal areas of myofibers degeneration with siginificant fibrosis. The cardiac muscle fibers of the rats in the group II (CKD) showed focal areas of cardiomyocytes degeneration and other areas of significantly hypertrophied fibers. The smooth muscle fibers of the lower esophageal sphincter of the rats in group II (CKD) showed no significant structural changes compared with the control group, however, the myenetric plexus showed multiple pyknotic and karyolitic nuclei with vacuolated cytoplasm. In addition, insignificant increase in the amount of collagen fibers was observed in almost all layers. Conclusion CKD produced moderate atrophy of skeletal muscle fibers, significant increase in the cardiomyocyte size and no significant structural effect of smooth muscle fibers of the lower esophageal sphincter.

Factor IX variants improve gene therapy efficacy for hemophilia B

Blood ◽  
2005 ◽  
Vol 105 (6) ◽  
pp. 2316-2323 ◽  
Author(s):  
Joerg Schuettrumpf ◽  
Roland W. Herzog ◽  
Alexander Schlachterman ◽  
Antje Kaufhold ◽  
Darrel W. Stafford ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Intramuscular Injection ◽  
Specific Activity ◽  
Factor Ix ◽  
Hemophilia B ◽  
Promising Strategy ◽  
B Mice ◽  
Higher Doses ◽  
Vector Delivery

Abstract Intramuscular injection of adeno-associated viral (AAV) vector to skeletal muscle of humans with hemophilia B is safe, but higher doses are required to achieve therapeutic factor IX (F.IX) levels. The efficacy of this approach is hampered by the retention of F.IX in muscle extracellular spaces and by the limiting capacity of muscle to synthesize fully active F.IX at high expression rates. To overcome these limitations, we constructed AAV vectors encoding F.IX variants for muscle- or liver-directed expression in hemophilia B mice. Circulating F.IX levels following intramuscular injection of AAV-F.IX-K5A/V10K, a variant with low-affinity to extracellular matrix, were 2-5 fold higher compared with wild-type (WT) F.IX, while the protein-specific activities remained similar. Expression of F.IX-R338A generated a protein with 2- or 6-fold higher specific activity than F.IX-WT following vector delivery to skeletal muscle or liver, respectively. F.IX-WT and variant forms provide effective hemostasis in vivo upon challenge by tail-clipping assay. Importantly, intramuscular injection of AAV-F.IX variants did not trigger antibody formation to F.IX in mice tolerant to F.IX-WT. These studies demonstrate that F.IX variants provide a promising strategy to improve the efficacy for a variety of gene-based therapies for hemophilia B.

scholarly journals Myomirnas Role in Als Suggest a Crosstalk between Muscle and Motor Neuron

2018 ◽  
Author(s):  
Valentina Pegoraro ◽  
Antonio Merico ◽  
Corrado Angelini
Keyword(s):  
Skeletal Muscle ◽  
Motor Neuron ◽  
Aerobic Exercise ◽  
Muscle Atrophy ◽  
Motor Neurons ◽  
Neuromuscular Junctions ◽  
Neurodegenerative Disorder ◽  
Disease Process ◽  
Muscle Fibres ◽  
Wide Range

Amyotrophic lateral sclerosis (ALS) is a rare, progressive, neurodegenerative disorder caused by degeneration of upper and lower motor neurons. The disease process leads from lower motor neuron involvement to progressive muscle atrophy, weakness, fasciculations for the upper motor neuron involvement to spasticity. Muscle atrophy in ALS is caused by a dysregulation in the molecular network controlling fast and slow muscle fibres. Denervation and reinnervation processes in skeletal muscle occur in the course of ALS and are modulated by rehabilitation. MicroRNAs (miRNAs) are small non-coding RNAs that modulate a wide range of biological functions under various pathophysiological conditions. MiRNAs can be secreted by various cell types and they are markedly stable in body fluids. MiR-1, miR-133 a, miR-133b, and miR-206 are called “myomiRs” and are considered markers of myogenesis during muscle regeneration and neuromuscular junction stabilization or sprouting. We observed a positive effect of a standard aerobic exercise rehabilitative protocol conducted for six weeks in 18 ALS patients during hospitalization in our center. We correlated clinical scales with molecular data on myomiRs. After six weeks of moderate aerobic exercise, myomiRNAs were down-regulated, suggesting an active proliferation of satellite cells in muscle and increased neuromuscular junctions. Our data suggest that circulating miRNAs modulate during skeletal muscle recovery in response to physical rehabilitation in ALS.

scholarly journals Molecular studies of exercise, skeletal muscle, and ageing

F1000Research ◽  
2016 ◽  
Vol 5 ◽  
pp. 1087 ◽  
Author(s):  
James A. Timmons ◽  
Iain J. Gallagher
Keyword(s):  
Skeletal Muscle ◽  
Research Capacity ◽  
Short Review ◽  
Neuromuscular Function ◽  
Potential Mechanism ◽  
Muscle Exercise ◽  
Methodological Issues ◽  
Physiological Capacity ◽  
New Concepts

The purpose of an F1000 review is to reflect on the bigger picture, exploring controversies and new concepts as well as providing opinion as to what is limiting progress in a particular field. We reviewed about 200 titles published in 2015 that included reference to ‘skeletal muscle, exercise, and ageing’ with the aim of identifying key articles that help progress our understanding or research capacity while identifying methodological issues which represent, in our opinion, major barriers to progress. Loss of neuromuscular function with chronological age impacts on both health and quality of life. We prioritised articles that studied human skeletal muscle within the context of age or exercise and identified new molecular observations that may explain how muscle responds to exercise or age. An important aspect of this short review is perspective: providing a view on the likely ‘size effect’ of a potential mechanism on physiological capacity or ageing.

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