scholarly journals Cytoplasmic actin in postsynaptic structures at the neuromuscular junction.

1981 ◽  
Vol 90 (3) ◽  
pp. 789-792 ◽  
Author(s):  
Z W Hall ◽  
B W Lubit ◽  
J H Schwartz
Keyword(s):  
Neuromuscular Junction ◽  
Mammalian Cells ◽  
Acetylcholine Receptors ◽  
Body Wall ◽  
Neuromuscular Junctions ◽  
Muscle Fibers ◽  
Adult Rat ◽  
Rat Muscle ◽  
Cytoplasmic Actin ◽  
Immunocytochemical Studies

We used an antibody prepared against Aplysia (mollusc) body-wall actin that specifically reacts with certain forms of cytoplasmic actin in mammalian cells to probe for the presence of actin at the neuromuscular junction. Immunocytochemical studies showed that actin or an actinlike molecule is concentrated at neuromuscular junctions of normal and denervated adult rat muscle fibers. Actin is present at the neuromuscular junctions of fibers of developing diaphragm muscles as early as embryonic day 18, well before postsynaptic folds are formed. These results suggest that cytoplasmic actin may play a role in the clustering or stabilization of acetylcholine receptors at the neuromuscular junction.

scholarly journals Association of beta-cytoplasmic actin with high concentrations of acetylcholine receptor (AChR) in normal and anti-AChR-treated primary rat muscle cultures.

1984 ◽  
Vol 32 (9) ◽  
pp. 973-981 ◽  
Author(s):  
B W Lubit
Keyword(s):  
Acetylcholine Receptor ◽  
Acetylcholine Receptors ◽  
Neuromuscular Junctions ◽  
Morphological Changes ◽  
Muscle Cells ◽  
High Concentration ◽  
Rat Muscle ◽  
Cytoplasmic Actin ◽  
High Concentrations

Previous immunocytochemical studies in which an antibody specific for mammalian cytoplasmic actin was used showed that a high concentration of cytoplasmic actin exists at neuromuscular junctions of rat muscle fibers such that the distribution of actin corresponded exactly to that of the acetylcholine receptors. Although clusters of acetylcholine receptors also are present in noninnervated rat and chick muscle cells grown in vitro, neither the mechanism for the formation and maintenance of these clusters nor the relationship of these clusters to the high density of acetylcholine receptors at the neuromuscular junction in vivo are known. In the present study, a relationship between beta-cytoplasmic actin and acetylcholine receptors in vitro has been demonstrated immunocytochemically using an antibody specific for the beta-form of cytoplasmic actin. Networks of cytoplasmic actin-containing filaments were found in discrete regions of the myotube membrane that also contained high concentrations of acetylcholine receptors; such high concentrations of acetylcholine receptors have been described in regions of membrane-substrate contact. Moreover, when primary rat myotubes were exposed to human myasthenic serum, gross morphological changes, accompanied by an apparent rearrangement of the cytoplasmic actin-containing cytoskeleton, were produced. Although whether the distribution of cytoplasmic actin-containing structures was influenced by the organization of acetylcholine receptor or vice versa cannot be determined from these studies, these findings suggest that in primary rat muscle cells grown in vitro, acetylcholine receptors and beta-cytoplasmic actin-containing structures may be somehow connected.

scholarly journals Basal lamina directs acetylcholinesterase accumulation at synaptic sites in regenerating muscle.

1985 ◽  
Vol 101 (3) ◽  
pp. 735-743 ◽  
Author(s):  
L Anglister ◽  
U J McMahan
Keyword(s):  
Plasma Membrane ◽  
Neuromuscular Junction ◽  
Basal Lamina ◽  
Acetylcholine Receptors ◽  
Skeletal Muscles ◽  
Ache Activity ◽  
Neuromuscular Junctions ◽  
Muscle Fibers ◽  
Synaptic Cleft

In skeletal muscles that have been damaged in ways which spare the basal lamina sheaths of the muscle fibers, new myofibers develop within the sheaths and neuromuscular junctions form at the original synaptic sites on them. At the regenerated neuromuscular junctions, as at the original ones, the muscle fibers are characterized by junctional folds and accumulations of acetylcholine receptors and acetylcholinesterase (AChE). The formation of junctional folds and the accumulation of acetylcholine receptors is known to be directed by components of the synaptic portion of the myofiber basal lamina. The aim of this study was to determine whether or not the synaptic basal lamina contains molecules that direct the accumulation of AChE. We crushed frog muscles in a way that caused disintegration and phagocytosis of all cells at the neuromuscular junction, and at the same time, we irreversibly blocked AChE activity. New muscle fibers were allowed to regenerate within the basal lamina sheaths of the original muscle fibers but reinnervation of the muscles was deliberately prevented. We then stained for AChE activity and searched the surface of the new muscle fibers for deposits of enzyme they had produced. Despite the absence of innervation, AChE preferentially accumulated at points where the plasma membrane of the new muscle fibers was apposed to the regions of the basal lamina that had occupied the synaptic cleft at the neuromuscular junctions. We therefore conclude that molecules stably attached to the synaptic portion of myofiber basal lamina direct the accumulation of AChE at the original synaptic sites in regenerating muscle. Additional studies revealed that the AChE was solubilized by collagenase and that it remained adherent to basal lamina sheaths after degeneration of the new myofibers, indicating that it had become incorporated into the basal lamina, as at normal neuromuscular junctions.

scholarly journals Concentration of Caveolin-3 at the Neuromuscular Junction in Young and Old Rat Skeletal Muscle Fibers

2003 ◽  
Vol 51 (9) ◽  
pp. 1113-1118 ◽  
Author(s):  
Bruce M. Carlson ◽  
Jean A. Carlson ◽  
Eduard I. Dedkov ◽  
Ian S. McLennan
Keyword(s):  
Skeletal Muscle ◽  
Neuromuscular Junction ◽  
Muscle Fibers ◽  
Normal Aging ◽  
Rat Skeletal Muscle ◽  
Phenotypic Characteristics ◽  
Adult Rat ◽  
Rat Muscle ◽  
Functional Implications ◽  
Old Rats

Caveolin-3, a muscle-specific member of the caveolin family, is strongly localized to the neuromuscular junction (NMJ) in adult rat muscle fibers, where it co-localizes with α-bungarotoxin staining. In 24-month-old rats, less distinct staining corresponds with the normal aging changes in the NMJ. After denervation, the pattern and intensity of staining begin to break up as early as 3 days, and by 10 days little staining remains. The functional implications of this concentration of caveolin-3 at the NMJ remain obscure, but it is possible that its absence could account for some of the phenotypic characteristics of individuals with caveolin-3 mutations.

scholarly journals Cytoskeletal components of the vertebrate neuromuscular junction: vinculin, alpha-actinin, and filamin.

1983 ◽  
Vol 97 (1) ◽  
pp. 217-223 ◽  
Author(s):  
R J Bloch ◽  
Z W Hall
Keyword(s):  
Neuromuscular Junction ◽  
Neuromuscular Junctions ◽  
Muscle Fibers ◽  
Cytoskeletal Proteins ◽  
Rat Muscle ◽  
Normal Rat ◽  
Specific Affinity

We have used immunocytochemical methods to investigate the cytoskeletal constituents of the vertebrate neuromuscular junction. Specific, affinity-purified antibodies to three cytoskeletal proteins, vinculin, alpha-actinin, and filamin, bound to neuromuscular junctions in sections of normal rat, mouse, chick, and Xenopus muscles. All three antibodies bound to the synaptic regions of denervated rat muscle fibers, indicating that the proteins recognized by these antibodies are associated with postsynaptic structures. The three proteins are present at the neuromuscular junction in muscle fibers of embryonic and neonatal animals, and therefore, may play an important role in its differentiation.

Acetylcholine receptors and nerve terminal distribution at the neuromuscular junction of long-term regenerated muscle fibers

2005 ◽  
Vol 34 (6) ◽  
pp. 387-396 ◽  
Author(s):  
Maria Julia Marques ◽  
Zarif T. R. Mendes ◽  
Elaine Minatel ◽  
Humberto Santo Neto
Keyword(s):  
Neuromuscular Junction ◽  
Nerve Terminal ◽  
Acetylcholine Receptors ◽  
Muscle Fibers

In vitro reinnervation of adult rat muscle fibres by foreign neurons and transformed chromaffin PC12 cells

1988 ◽  
Vol 234 (1274) ◽  
pp. 1-9 ◽  
Keyword(s):  
Pc12 Cells ◽  
Neuromuscular Junctions ◽  
Mean Amplitude ◽  
Muscle Fibres ◽  
Adult Rat ◽  
Rat Muscle ◽  
Pheochromocytoma Pc12 ◽  
Nerve Muscle ◽  
Miniature Endplate Potentials

Adult rat muscle fibres were dissociated by using collagenase and maintained in culture. One to nine days later, neurons obtained from stages 22–30 Xenopus laevis embryos, or neonatal spinal cord, or pheochromocytoma (PC12) cells treated with nerve growth factor were added. Subsequently, the co-cultures were maintained for up to eight days. Functional synapses were formed with variable efficiency: 12% in rat– Xenopus nerve–muscle co-cultures, 23% in rat–rat and 33% in PC12 co-cultures. Miniature endplate potentials(MEPPs) and currents (MEPCs) were recorded, at frequencies ranging from 0.01 to 0.9 Hz. Their mean amplitude was smaller than in normal mammalian muscles. The rise time and time-constant of decay of MEPCs was about seven to ten times longer than that found in the original muscle, resembling immature synapses. (+)-Tubocurarine abolished the MEPPs in the rat-PC12 neuromuscular junctions. It is concluded that dissociated adult rat muscle fibres retain their ability of being reinnervated, and can form functional synapses with foreign neurons and transformed chromaffin cells.

scholarly journals Adrenoceptors Modulate Cholinergic Synaptic Transmission at the Neuromuscular Junction

2021 ◽  
Vol 22 (9) ◽  
pp. 4611
Author(s):  
Ellya Bukharaeva ◽  
Venera Khuzakhmetova ◽  
Svetlana Dmitrieva ◽  
Andrei Tsentsevitsky
Keyword(s):  
Neuromuscular Junction ◽  
Neurodegenerative Diseases ◽  
Acetylcholine Receptors ◽  
Molecular Mechanisms ◽  
Acetylcholine Release ◽  
Neuromuscular Junctions ◽  
Motor Nerve ◽  
Nerve Terminals ◽  
Adrenergic Agents ◽  
Cholinergic Synaptic Transmission

Adrenoceptor activators and blockers are widely used clinically for the treatment of cardiovascular and pulmonary disorders. More recently, adrenergic agents have also been used to treat neurodegenerative diseases. Recent studies indicate a location of sympathetic varicosities in close proximity to neuromuscular junctions. The pressing question is whether there could be any effects of endo- or exogenous catecholamines on cholinergic neuromuscular transmission. It was shown that the pharmacological stimulation of adrenoceptors, as well as sympathectomy, can affect both acetylcholine release from motor nerve terminals and the functioning of postsynaptic acetylcholine receptors. In this review, we discuss the recent data regarding the effects of adrenergic drugs on neurotransmission at the neuromuscular junction. The elucidation of the molecular mechanisms by which the clinically relevant adrenomimetics and adrenoblockers regulate quantal acetylcholine release from the presynaptic nerve terminals and postsynaptic sensitivity may help in the design of highly effective and well-tolerated sympathomimetics for treating a number of neurodegenerative diseases accompanied by synaptic defects.

scholarly journals An antiactin antibody that distinguishes between cytoplasmic and skeletal muscle actins.

1980 ◽  
Vol 86 (3) ◽  
pp. 891-897 ◽  
Author(s):  
B W Lubit ◽  
J H Schwartz
Keyword(s):  
Skeletal Muscle ◽  
Body Wall ◽  
Human Fibroblasts ◽  
Aplysia Californica ◽  
Membrane Systems ◽  
Intense Staining ◽  
Marine Mollusc ◽  
Cytoplasmic Actin ◽  
Great Excess ◽  
Immunocytochemical Studies

We elicited antibodies in rabbits to actin purified from body wall muscle of the marine mollusc, Aplysia californica. We found that this antiactin has an unusual specificity: in addition to reacting with the immunogen, it recognizes cytoplasmic vertebrate actins but not myofibrillar actin. Radioimmunoassay showed little or no cross-reaction with actin purified from either chicken gizzard or rabbit skeletal muscle. Immunocytochemical studies with human fibroblasts and L6 myoblasts revealed intense staining of typical cytoplasmic cables. Myofibrils were not stained after treatment of human and frog skeletal muscle with the antibody, although the distribution of immunofluorescence suggested that cytoplasmic actin is associated with membrane systems in the muscle fiber. The antibody may therefore be especially suited for studying the localization of cytoplasmic actin in skeletal muscle cells even in the presence of a great excess of the myofibrillar form.

Sign in / Sign up

Export Citation Format

Share Document