scholarly journals DEVELOPMENT OF THE NEUROMUSCULAR JUNCTION

1972 ◽  
Vol 55 (1) ◽  
pp. 93-103 ◽  
Author(s):  
Thomas L. Lentz
Keyword(s):  
Schwann Cell ◽  
Cholinesterase Activity ◽  
Neuromuscular Junctions ◽  
Synaptic Cleft ◽  
Axon Terminals ◽  
End Plate ◽  
Motor End Plate ◽  
Motor End Plates

To determine the effects of nerve explants on the integrity of motor end plates in vitro, cholinesterase activity and structure of end plates were compared in newt muscle denervated in vivo, cultured in the absence of nerve explants, and cultured in the presence of sensory ganglia. In neuromuscular junctions denervated in vivo or in vitro, the synaptic vesicles become clumped and fragmented. A few intact vesicles escape into the synaptic cleft. Axon terminals degenerate until they are left as residual bodies within the Schwann cell cytoplasm. Junctional folds on the muscle surface are reduced in height and are no longer evident once traces of axoplasm within the Schwann cell disappear. End plate cholinesterase activity is reduced as junctional folds are lost. When muscle is cultured in the presence of a sensory ganglion, the terminal axoplasm degenerates in the same manner but junctional folds persist on the muscle surface. Moderately intense cholinesterase activity remains in association with the junctional folds, so that normal motor end plates are maintained in the absence of innervation. These results show that degenerative changes in the structure of the motor end plate and loss of cholinesterase activity occurring in organ culture as a result of denervation can be retarded by nerve explants that do not directly innervate the muscle.

scholarly journals MOTOR END PLATE REACTIVITY TO DIVALENT METAL IONS HISTOCHEMICAL STUDIES

1967 ◽  
Vol 15 (5) ◽  
pp. 276-284 ◽  
Author(s):  
TOSHIO NAKAMURA ◽  
TATSUJI NAMBA ◽  
DAVID GROB
Keyword(s):  
Metal Ions ◽  
Metal Binding ◽  
Calcium Release ◽  
Cholinesterase Activity ◽  
Divalent Metal ◽  
Divalent Metal Ions ◽  
Alizarin Red ◽  
End Plate ◽  
Motor End Plate

Motor end plates in the tibialis anterior muscle of the rat were demonstrated by metal sulfide deposits following injection of aqueous solutions of lead, stannous, cadmium, zinc or cupric ions into the muscle in vivo or in vitro. The appearance of the end plates was similar to the structure demonstrated by cholinesterase staining, with visualization of the subneural apparatus. Neither metal binding nor cholinesterase activity was affected 4 weeks after dissection of the sciatic nerve, indicating that the metal binding site is postsynaptic. Freezing or formalin fixation of muscle prevented binding of all metal ions to the end plate without greatly affecting cholinesterase activity, indicating that these two activities of the end plate are distinct. Prior administration of acetylcholine, d-tubocurarine, neostigmine or diisopropyl fluorophosphate inhibited binding to the end plate of cadmium and zinc ions but did not alter binding of lead and stannous ions. By formation of a lake with alizarin red S previously injected in vivo intramuscularly, the release of calcium ions at the motor end plate following stimulation of the muscle through the nerve or administration of neostigmine was demonstrated. These results suggest a close relationship of the site of binding of divalent metal ions in the motor end plate to the site of calcium release, and a close but not identical relationship to the site of cholinesterase activity and the acetylcholine receptor.

scholarly journals Acetylcholinesterase from the motor nerve terminal accumulates on the synaptic basal lamina of the myofiber.

1991 ◽  
Vol 115 (3) ◽  
pp. 755-764 ◽  
Author(s):  
L Anglister
Keyword(s):  
Basal Lamina ◽  
Ache Activity ◽  
Neuromuscular Junctions ◽  
Motor Nerve ◽  
Synaptic Cleft ◽  
Motor Nerve Terminal ◽  
Nerve Terminals ◽  
Axon Terminals ◽  
Muscle Nerve ◽  
Almost All

Acetylcholinesterase (AChE) in skeletal muscle is concentrated at neuromuscular junctions, where it is found in the synaptic cleft between muscle and nerve, associated with the synaptic portion of the myofiber basal lamina. This raises the question of whether the synaptic enzyme is produced by muscle, nerve, or both. Studies on denervated and regenerating muscles have shown that myofibers can produce synaptic AChE, and that the motor nerve may play an indirect role, inducing myofibers to produce synaptic AChE. The aim of this study was to determine whether some of the AChE which is known to be made and transported by the motor nerve contributes directly to AChE in the synaptic cleft. Frog muscles were surgically damaged in a way that caused degeneration and permanent removal of all myofibers from their basal lamina sheaths. Concomitantly, AChE activity was irreversibly blocked. Motor axons remained intact, and their terminals persisted at almost all the synaptic sites on the basal lamina in the absence of myofibers. 1 mo after the operation, the innervated sheaths were stained for AChE activity. Despite the absence of myofibers, new AChE appeared in an arborized pattern, characteristic of neuromuscular junctions, and its reaction product was concentrated adjacent to the nerve terminals, obscuring synaptic basal lamina. AChE activity did not appear in the absence of nerve terminals. We concluded therefore, that the newly formed AChE at the synaptic sites had been produced by the persisting axon terminals, indicating that the motor nerve is capable of producing some of the synaptic AChE at neuromuscular junctions. The newly formed AChE remained adherent to basal lamina sheaths after degeneration of the terminals, and was solubilized by collagenase, indicating that the AChE provided by nerve had become incorporated into the basal lamina as at normal neuromuscular junctions.

scholarly journals In Vitro and In Silico Antioxidant, Anti-Diabetic, Anti-HIV and Anti-Alzheimer Activity of Endophytic Fungi, Cladosporium uredinicola Phytochemicals

2019 ◽  
Vol 13 ◽  
pp. 13-34
Author(s):  
Melappa Govindappa ◽  
V. Thanuja ◽  
S. Tejashree ◽  
C.A. Soukhya ◽  
Suresh Barge ◽  
...  
Keyword(s):  
Qualitative Method ◽  
Cholinesterase Activity ◽  
Methanol Extract ◽  
High Binding Energy ◽  
Acetyl Cholinesterase ◽  
Gp 120 ◽  
Anti Hiv ◽  
Hiv 1

The present work was aimed to identify phytochemicals in C. uredinicola methanol extract from qualitative, TLC and GC-MS method and evaluated for antioxidant, anti-HIV, anti-diabetes, anti-cholinesterase activity in vitro and in silico. The C. uredinicola extract showed flavonoids, tannins, alkaloids, glycosides, phenols, terpenoids, and coumarins presence in qualitative method. From GC-MS analysis, identified seven different phytochemicals and out of seven, four (coumarin, coumarilic acid, hymecromone, alloisoimperatorin) are coumarins. The C. uredinicola extract have shown significant antioxidant activity in DPPH (73) and FRAP (1359) method. The HIV-1 RT (83.81+2.14), gp 120 (80.24+2.31), integrase (79.43+3.14) and protease (77.63+2.14), DPPIV, β-glucosidase and acetyl cholinesterase activity was significantly reduced by the extract. The 2-diphenylmethyleneamino methyl ester had shown significant interaction with oxidant and HIV-1 proteins whereas alloisoimperatorin have interacted with diabetes and cholinesterase proteins followed by hymecromone with high binding energy. These three phytochemicals are non-carcinogens, non-toxic, readily degradable and have drug likeliness properties. The C. uredinicola phytochemicals are responsible for management of diabetes, HIV-1 and Alzheimer. Further in vivo work is needed to justify our research.

scholarly journals Regulation of SH3PX1 by dNedd4-long at the Drosophila neuromuscular junction

2018 ◽  
Vol 294 (5) ◽  
pp. 1739-1752 ◽  
Author(s):  
Samantha S. Wasserman ◽  
Alina Shteiman-Kotler ◽  
Kathryn Harris ◽  
Konstantin G. Iliadi ◽  
Avinash Persaud ◽  
...  
Keyword(s):  
Neurotransmitter Release ◽  
Neuromuscular Junctions ◽  
Cell Periphery ◽  
Middle Region ◽  
Binding Partners ◽  
Direct Binding ◽  
Specific Regulation ◽  
Neuromuscular Synaptogenesis

Drosophila Nedd4 (dNedd4) is a HECT E3 ubiquitin ligase present in two major isoforms: short (dNedd4S) and long (dNedd4Lo), with the latter containing two unique regions (N terminus and Middle). Although dNedd4S promotes neuromuscular synaptogenesis (NMS), dNedd4Lo inhibits it and impairs larval locomotion. To explain how dNedd4Lo inhibits NMS, MS analysis was performed to find its binding partners and identified SH3PX1, which binds dNedd4Lo unique Middle region. SH3PX1 contains SH3, PX, and BAR domains and is present at neuromuscular junctions, where it regulates active zone ultrastructure and presynaptic neurotransmitter release. Here, we demonstrate direct binding of SH3PX1 to the dNedd4Lo Middle region (which contains a Pro-rich sequence) in vitro and in cells, via the SH3PX1-SH3 domain. In Drosophila S2 cells, dNedd4Lo overexpression reduces SH3PX1 levels at the cell periphery. In vivo overexpression of dNedd4Lo post-synaptically, but not pre-synaptically, reduces SH3PX1 levels at the subsynaptic reticulum and impairs neurotransmitter release. Unexpectedly, larvae that overexpress dNedd4Lo post-synaptically and are heterozygous for a null mutation in SH3PX1 display increased neurotransmission compared with dNedd4Lo or SH3PX1 mutant larvae alone, suggesting a compensatory effect from the remaining SH3PX1 allele. These results suggest a post-synaptic–specific regulation of SH3PX1 by dNedd4Lo.

scholarly journals Pmp22 super-enhancer deletion causes tomacula formation and conduction block in peripheral nerves

2020 ◽  
Vol 29 (10) ◽  
pp. 1689-1699
Author(s):  
Harrison Pantera ◽  
Bo Hu ◽  
Daniel Moiseev ◽  
Chris Dunham ◽  
Jibraan Rashid ◽  
...  
Keyword(s):  
Peripheral Neuropathy ◽  
Schwann Cell ◽  
Copy Number ◽  
Regulatory Elements ◽  
Copy Number Variations ◽  
Hereditary Neuropathy ◽  
Peripheral Myelin Protein 22 ◽  
Super Enhancer

Abstract Copy number variation of the peripheral nerve myelin gene Peripheral Myelin Protein 22 (PMP22) causes multiple forms of inherited peripheral neuropathy. The duplication of a 1.4 Mb segment surrounding this gene in chromosome 17p12 (c17p12) causes the most common form of Charcot-Marie-Tooth disease type 1A, whereas the reciprocal deletion of this gene causes a separate neuropathy termed hereditary neuropathy with liability to pressure palsies (HNPP). PMP22 is robustly induced in Schwann cells in early postnatal development, and several transcription factors and their cognate regulatory elements have been implicated in coordinating the gene’s proper expression. We previously found that a distal super-enhancer domain was important for Pmp22 expression in vitro, with particular impact on a Schwann cell-specific alternative promoter. Here, we investigate the consequences of deleting this super-enhancer in vivo. We find that loss of the super-enhancer in mice reduces Pmp22 expression throughout development and into adulthood, with greater impact on the Schwann cell-specific promoter. Additionally, these mice display tomacula formed by excessive myelin folding, a pathological hallmark of HNPP, as have been previously observed in heterozygous Pmp22 mice as well as sural biopsies from patients with HNPP. Our findings demonstrate a mechanism by which smaller copy number variations, not including the Pmp22 gene, are sufficient to reduce gene expression and phenocopy a peripheral neuropathy caused by the HNPP-associated deletion encompassing PMP22.

Axonal signalling and the making of olfactory ensheathing cells: a hypothesis

2006 ◽  
Vol 2 (3) ◽  
pp. 217-224 ◽  
Author(s):  
KONSTANTIN WEWETZER ◽  
GUDRUN BRANDES
Keyword(s):  
Schwann Cell ◽  
Schwann Cells ◽  
Specific Interaction ◽  
Neurotrophin Receptor ◽  
Olfactory Ensheathing Cells ◽  
Experimental Conditions ◽  
Neural Repair ◽  
Ensheathing Cells

Olfactory ensheathing cells (OECs) are Schwann cell-like glial cells of the olfactory system that promote neural repair under experimental conditions. It is a matter of debate in how far OECs resemble Schwann cells and whether they possess specific properties. Although OECs have been characterized mainly with respect to their regenerative effects after transplantation, both their cellular identity and the regulating factors involved have remained vague. The aim of this article is to define OEC and Schwann-cell identity in molecular terms, and to discuss crucial factors that are involved in determination in vitro and in vivo. Distinct OEC features such as the down-regulation of the low affinity neurotrophin receptor p75NTR by neuronal contact are apparent in vivo under physiological conditions, whereas OECs acquire a Schwann cell-like phenotype and up-regulate p75NTR expression in vitro and following transplantation into the lesioned spinal cord. This might indicate that establishment of the OEC phenotype depends on specific axonal stimuli. In this review we hypothesize that OECs and Schwann cells possess malleable cellular phenotypes that acquire distinct features only upon specific interaction with their natural neuronal partner. This concept is consistent with previous findings in vitro and in vivo, and might be relevant for studies that use OECs and Schwann cells for nervous system repair.

scholarly journals HP1-β is required for development of the cerebral neocortex and neuromuscular junctions

2008 ◽  
Vol 183 (4) ◽  
pp. 597-606 ◽  
Author(s):  
Rebecca Aucott ◽  
Jörn Bullwinkel ◽  
Yang Yu ◽  
Wei Shi ◽  
Mustafa Billur ◽  
...  
Keyword(s):  
Neuromuscular Junctions ◽  
Physiological Function ◽  
Newborn Mice ◽  
Cerebral Cortex Development ◽  
Neuronal Precursors ◽  
Perinatal Lethality ◽  
Cerebral Neocortex ◽  
Hp1 Proteins

HP1 proteins are thought to be modulators of chromatin organization in all mammals, yet their exact physiological function remains unknown. In a first attempt to elucidate the function of these proteins in vivo, we disrupted the murine Cbx1 gene, which encodes the HP1-β isotype, and show that the Cbx1−/−-null mutation leads to perinatal lethality. The newborn mice succumbed to acute respiratory failure, whose likely cause is the defective development of neuromuscular junctions within the endplate of the diaphragm. We also observe aberrant cerebral cortex development in Cbx1−/− mutant brains, which have reduced proliferation of neuronal precursors, widespread cell death, and edema. In vitro cultures of neurospheres from Cbx1−/− mutant brains reveal a dramatic genomic instability. Our results demonstrate that HP1 proteins are not functionally redundant and that they are likely to regulate lineage-specific changes in heterochromatin organization.

scholarly journals Ets-2 Repressor Factor Silences Extrasynaptic Utrophin by N-Box–mediated Repression in Skeletal Muscle

2007 ◽  
Vol 18 (8) ◽  
pp. 2864-2872 ◽  
Author(s):  
Kelly J. Perkins ◽  
Utpal Basu ◽  
Murat T. Budak ◽  
Caroline Ketterer ◽  
Santhosh M. Baby ◽  
...  
Keyword(s):  
Promoter Activity ◽  
Molecular Mechanisms ◽  
Neuromuscular Junctions ◽  
Protein Product ◽  
Mrna Levels ◽  
Laser Capture Microscopy ◽  
Erk Phosphorylation ◽  
Duchenne's Muscular Dystrophy

Utrophin is the autosomal homologue of dystrophin, the protein product of the Duchenne's muscular dystrophy (DMD) locus. Utrophin expression is temporally and spatially regulated being developmentally down-regulated perinatally and enriched at neuromuscular junctions (NMJs) in adult muscle. Synaptic localization of utrophin occurs in part by heregulin-mediated extracellular signal-regulated kinase (ERK)-phosphorylation, leading to binding of GABPα/β to the N-box/EBS and activation of the major utrophin promoter-A expressed in myofibers. However, molecular mechanisms contributing to concurrent extrasynaptic silencing that must occur to achieve NMJ localization are unknown. We demonstrate that the Ets-2 repressor factor (ERF) represses extrasynaptic utrophin-A in muscle. Gel shift and chromatin immunoprecipitation studies demonstrated physical association of ERF with the utrophin-A promoter N-box/EBS site. ERF overexpression repressed utrophin-A promoter activity; conversely, small interfering RNA-mediated ERF knockdown enhanced promoter activity as well as endogenous utrophin mRNA levels in cultured muscle cells in vitro. Laser-capture microscopy of tibialis anterior NMJ and extrasynaptic transcriptomes and gene transfer studies provide spatial and direct evidence, respectively, for ERF-mediated utrophin repression in vivo. Together, these studies suggest “repressing repressors” as a potential strategy for achieving utrophin up-regulation in DMD, and they provide a model for utrophin-A regulation in muscle.

Ultrastructure of intraocular muscles of diving and nondiving ducks

1982 ◽  
Vol 60 (7) ◽  
pp. 1588-1606 ◽  
Author(s):  
J. G. Sivak ◽  
O. E. Vrablic
Keyword(s):  
Neuromuscular Junctions ◽  
Muscle Fibres ◽  
Dark Cell ◽  
Domestic Ducks ◽  
Diving Ducks ◽  
Light Cell ◽  
Axon Terminals ◽  
End Plate ◽  
Transmission Electron ◽  
Skeletal Muscle Fibres

The fine structure of ciliary muscle (CM), iris sphincter (IS), and neuromuscular junctions (NMJ) were studied by light and transmission electron microscopy in domestic ducks (Anas platyrhynchos) and diving ducks (Mergus merganser). Previous work has shown that the iris produces exaggerated acommodative ability in the diver. Both muscles are striated in the two species. While both muscles of domestic ducks and the CM of the diving ducks consist of one cell type, the IS of the latter is made up of two types of cells referred to as "light" and "dark." The "light" cell has long, thin, uniformly distributed mitochondria, while in the "dark" cells they are large, unevenly dispersed and often aggregated subsarcolemmally. The sarcoplasmic reticulum is more abundant in both IS and CM of domestic ducks, while well developed T tubules are seen more regularly in the intraocular muscles of diving ducks.The NMJ's do not show the complexity seen in singly innervated skeletal muscle fibres. All the nerve axon terminals end in a flat shallow trough and postjunctional folds are either nonexistent or very shallow. The NMJ's of the IS of domestic ducks and of the "dark" cell of the IS of diving ducks consist of a large single end plate. That of the CM of domestic ducks consists of a diffuse single end plate while the NMJ of the CM of diving ducks consists of diffuse multiple endings. Nerve endings of similar size and structure but occurring only singly were found on the "light" cell of the IS of domestic ducks.

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