Effect of a plant-derived spider toxin analogue on crayfish neuromuscular junctions

1998 ◽  
Vol 76 (11) ◽  
pp. 2103-2107 ◽  
Author(s):  
A J Mercier ◽  
S Farragher ◽  
B Schmor ◽  
M Kamau ◽  
J Atkinson
Keyword(s):  
Procambarus Clarkii ◽  
Neuromuscular Junctions ◽  
Physiological Saline ◽  
Structural Similarity ◽  
Hydroxycinnamic Acid ◽  
Similar Compound ◽  
Neuromuscular Synapses ◽  
Spider Toxin ◽  
Spider Toxins ◽  
Polyamine Conjugates

N8-Coumaroyl spermidine (N8-CS) is an example of hydroxycinnamic acid - polyamine conjugates found in certain plants. Because of its structural similarity to some spider toxins, N8-CS was tested for its ability to block arthropod neuromuscular synapses. It inhibited chemical synaptic transmission at crayfish (Procambarus clarkii) neuromuscular junctions, the IC50 being approximately 200 µM. Its effect was at least partially reversed by washing with physiological saline. Joro spider toxin, a structurally similar compound, also blocked crayfish neuromuscular synapses but its effect was irreversible. These results suggest that plant-derived cinnamoyl spermidines might have paralytic properties similar to those of spider toxins.

Physiological effects of two FMRFamide-related peptides from the crayfish Procambarus clarkii

1995 ◽  
Vol 198 (1) ◽  
pp. 109-116
Author(s):  
M Skerrett ◽  
A Peaire ◽  
P Quigley ◽  
A Mercier
Keyword(s):  
Transmitter Release ◽  
Procambarus Clarkii ◽  
Neuromuscular Junctions ◽  
Input Resistance ◽  
Physiological Effects ◽  
Synaptic Current ◽  
Extensor Muscles ◽  
Neuromuscular Systems ◽  
Dose Dependent ◽  
Measurable Change

The present study examined the effects of two recently identified neuropeptides on crayfish hearts and on neuromuscular junctions of the crayfish deep abdominal extensor muscles. The two peptides, referred to as NF1 (Asn-Arg-Asn-Phe-Leu-Arg-Phe-NH2) and DF2 (Asp-Arg-Asn-Phe-Leu-Arg-Phe-NH2), increased the rate and amplitude of spontaneous cardiac contractions and increased the amplitude of excitatory junctional potentials (EJPs) in the deep extensors. Both effects were dose-dependent, but threshold and EC50 values for the cardiac effects were at least 10 times lower than for the deep extensor effects. The heart responded equally well to three sequential applications of peptide in any given preparation, but the responses of the deep extensors appeared to decline with successive peptide applications. The results support the hypothesis that these two neuropeptides act as neurohormones to modulate the cardiac and neuromuscular systems in crayfish. Quantal synaptic current recordings from the deep extensor muscles indicate that both peptides increase the number of quanta of transmitter released from synaptic terminals. Neither peptide elicited a measurable change in the size of quantal synaptic currents. NF1 caused a small increase in muscle cell input resistance, while DF2 did not alter input resistance. These data suggest that DF2 increases EJP amplitudes primarily by increasing transmitter release, while the increase elicited by NF1 appears to involve presynaptic and postsynaptic mechanisms.

Lanthanum penetration in crayfish nervous system: observations on intact and ‘desheathed’ preparations

1977 ◽  
Vol 23 (1) ◽  
pp. 315-324
Author(s):  
N.J. Lane ◽  
L.S. Swales ◽  
N.J. Abbott
Keyword(s):  
Nervous System ◽  
Glial Cells ◽  
Peripheral Nerves ◽  
Procambarus Clarkii ◽  
Physiological Saline ◽  
The Other ◽  
Major Site ◽  
Electrophysiological Studies ◽  
Cell Processes ◽  
Tubular Lattice

Central neural connectives and peripheral nerves from the crayfish Procambarus clarkii were incubated in 5 mM lanthanum solutions in physiological saline, for periods from 15 min to 2 h. The tracer only rarely reaches the axon surfaces in the perineurium-ensheathed connectives, penetrating the elaborate perineurial layer slowly. In peripheral nerves, on the other hand, where the perineurium is extermely attenuated and interrupted by open extracellular clefts, inward movement of lanthanum to the axon surfaces occurs readily. When the perineurial layer of the neural connectives is removed by ‘desheathing’, penetration of the tracer to the level of the axolemma occurs rapidly, implicating the perineurium as the major site of restriction of entry of large ions and exogenous molecules. This conclusion is discussed in relation to recent electrophysiological studies on K+ movements. In both peripheral nerves and desheathed connectives, the transcellular tubular lattice system present in crustacean glial cells appears to serve as a route for the entry of tracer to the axon surfaces, and is more direct than the long and complex extracellular pathway formed by the interdigitations of the extensive glial cell processes.

Limits to the Development of Fast Neuromuscular Transmission in Zebrafish

2001 ◽  
Vol 86 (6) ◽  
pp. 2951-2956 ◽  
Author(s):  
Pierre Drapeau ◽  
Robert R. Buss ◽  
Declan W. Ali ◽  
Pascal Legendre ◽  
Richard L. Rotundo
Keyword(s):  
Time Course ◽  
Neuromuscular Junctions ◽  
Synaptic Cleft ◽  
Muscle Membrane ◽  
High Concentration ◽  
Limited Region ◽  
Neuromuscular Synapses ◽  
Transmission Electron ◽  
Order Of Magnitude ◽  
High Concentrations

Zebrafish embryos have small and slow miniature end-plate currents (mEPCs), whereas only a few days later larval mEPCs are an order of magnitude larger and faster, being among the fastest of all neuromuscular synapses. To identify the bases for these changes we compared, in embryos and larvae, the properties and distributions of acetylcholine (ACh) receptors (AChRs) and acetylcholinesterase (AChE) as well as the ultrastructure of the developing neuromuscular junctions (NMJs). To mimic synaptic release, patches of muscle membrane were exposed briefly (for 1 ms) to a saturating concentration (10 mM) of ACh. The AChR deactivation kinetics were twice as slow in embryos compared with larvae. In both embryos and larvae, AChRs demonstrated open channel block by millimolar ACh, and this was detected during mEPCs, indicating that a high concentration of ACh is released at immature and mature NMJs. AChR and AChE distributions were compared using the selective fluorescently conjugated labels α-bungarotoxin and fasciculin 2, respectively. In larvae, punctate AChR clusters were detected whereas junctional AChE staining was less intense than that found at adult NMJs. Transmission electron microscopy revealed immature nerve endings in embryos that were closely juxtaposed to the surrounding muscle cells, whereas mature larval NMJs had a wider synaptic cleft with a conspicuous basal lamina over a limited region of synaptic contact. Our results indicate that ACh is released at high concentrations at immature NMJs, but its clearance is prolonged and the AChRs are dispersed, resulting in a slow mEPC time course until a mature cleft appears with densely packed faster AChRs and abundant AChE.

scholarly journals Muscle-Derived Extracellular Signal-Regulated Kinases 1 and 2 Are Required for the Maintenance of Adult Myofibers and Their Neuromuscular Junctions

2015 ◽  
Vol 35 (7) ◽  
pp. 1238-1253 ◽  
Author(s):  
Bonnie Seaberg ◽  
Gabrielle Henslee ◽  
Shuo Wang ◽  
Ximena Paez-Colasante ◽  
Gary E. Landreth ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Tibialis Anterior ◽  
Neuromuscular Junctions ◽  
Germ Line ◽  
Fiber Type ◽  
Postnatal Growth ◽  
Mammalian Skeletal Muscle ◽  
Neuromuscular Synapses ◽  
Extracellular Signal

The Ras–extracellular signal-regulated kinase 1 and 2 (ERK1/2) pathway appears to be important for the development, maintenance, aging, and pathology of mammalian skeletal muscle. Yet no gene targeting ofErk1/2in muscle fibersin vivohas been reported to date. We combined a germ lineErk1mutation with Cre-loxPErk2inactivation in skeletal muscle to produce, for the first time, mice lacking ERK1/2 selectively in skeletal myofibers. Animals lacking muscle ERK1/2 displayed stunted postnatal growth, muscle weakness, and a shorter life span. Their muscles examined in this study, sternomastoid and tibialis anterior, displayed fragmented neuromuscular synapses and a mixture of modest fiber atrophy and loss but failed to show major changes in fiber type composition or absence of cell surface dystrophin. Whereas the lack of only ERK1 had no effects on the phenotypes studied, the lack of myofiber ERK2 explained synaptic fragmentation in the sternomastoid but not the tibialis anterior and a decrease in the expression of the acetylcholine receptor (AChR) epsilon subunit gene mRNA in both muscles. A reduction in AChR protein was documented in line with the above mRNA results. Evidence of partial denervation was found in the sternomastoid but not the tibialis anterior. Thus, myofiber ERK1/2 are differentially required for the maintenance of myofibers and neuromuscular synapses in adult mice.

scholarly journals NMJ-Analyser: high-throughput morphological screening of neuromuscular junctions identifies subtle changes in mouse neuromuscular disease models

2020 ◽  
Author(s):  
Alan Mejia Maza ◽  
Seth Jarvis ◽  
Weaverly Colleen Lee ◽  
Thomas J. Cunningham ◽  
Giampietro Schiavo ◽  
...  
Keyword(s):  
Machine Learning ◽  
High Throughput ◽  
Neuromuscular Disease ◽  
Structural Changes ◽  
Neuromuscular Junctions ◽  
Learning Algorithm ◽  
Neuromuscular Diseases ◽  
Morphological Structure ◽  
Disease Models ◽  
Neuromuscular Synapses

AbstractThe neuromuscular junction (NMJ) is the peripheral synapse formed between a motor neuron axon terminal and a muscle fibre. NMJs are thought to be the primary site of peripheral pathology in many neuromuscular diseases, but innervation/denervation status is often assessed qualitatively with poor systematic criteria across studies, and separately from 3D morphological structure. Here, we describe the development of ‘NMJ-Analyser’, to comprehensively screen the morphology of NMJs and their corresponding innervation status automatically. NMJ-Analyser generates 29 biologically relevant features to quantitatively define healthy and aberrant neuromuscular synapses and applies machine learning to diagnose NMJ degeneration. We validated this framework in longitudinal analyses of wildtype mice, as well as in four different neuromuscular disease models: three for amyotrophic lateral sclerosis (ALS) and one for peripheral neuropathy. We showed that structural changes at the NMJ initially occur in the nerve terminal of mutant TDP43 and FUS ALS models. Using a machine learning algorithm, healthy and aberrant neuromuscular synapses are identified with 95% accuracy, with 88% sensitivity and 97% specificity. Our results validate NMJ-Analyser as a robust platform for systematic and structural screening of NMJs, and pave the way for transferrable, and cross-comparison and high-throughput studies in neuromuscular diseases.

scholarly journals Sodium channels aggregate at former synaptic sites in innervated and denervated regenerating muscles

1994 ◽  
Vol 124 (1) ◽  
pp. 139-147 ◽  
Author(s):  
MT Lupa ◽  
JH Caldwell
Keyword(s):  
Sodium Channels ◽  
Basal Lamina ◽  
Time Course ◽  
Neuromuscular Junctions ◽  
Nerve Terminals ◽  
Subsequent Increase ◽  
Synaptic Density ◽  
Neuromuscular Synapses ◽  
Snake Toxin

The role of innervation in the establishment and regulation of the synaptic density of voltage-activated Na channels (NaChs) was investigated at regenerating neuromuscular junctions. Rat muscles were induced to degenerate after injection of the Australian tiger snake toxin, notexin. The loose-patch voltage clamp technique was used to measure the density and distribution of NaChs on muscle fibers regenerating with or without innervation. In either case, new myofibers formed within the original basal lamina sheaths, and, NaChs became concentrated at regenerating endplates nearly as soon as they formed. The subsequent increase in synaptic NaCh density followed a time course similar to postnatal muscles. Neuromuscular endplates regenerating after denervation, with no nerve terminals present, had NaCh densities not significantly different from endplates regenerating in the presence of nerve terminals. The results show that the nerve terminal is not required for the development of an enriched NaCh density at regenerating neuromuscular synapses and implicate Schwann cells or basal lamina as the origin of the signal for NaCh aggregation. In contrast, the change in expression from the immature to the mature form of the NaCh isoform that normally accompanies development occurred only partially on muscles regenerating in the absence of innervation. This aspect of NaCh regulation is thus dependent upon innervation.

Latency of transmitter release at crayfish motor nerve endings examined by intracellular depolarization

1987 ◽  
Vol 65 (1) ◽  
pp. 105-108 ◽  
Author(s):  
J. M. Wojtowicz ◽  
I. Parnas ◽  
H. Parnas ◽  
H. L. Atwood
Keyword(s):  
Transmitter Release ◽  
Sampling Methods ◽  
Procambarus Clarkii ◽  
Neuromuscular Junctions ◽  
Motor Nerve ◽  
Nerve Endings ◽  
Quantal Release ◽  
Moderate Size ◽  
Axon Branch ◽  
Individual Motor

Latency of release of individual quanta of transmitter was studied at neuromuscular junctions of a crayfish (Procambarus clarkii). Postsynaptic quantal currents were recorded at individual motor nerve endings with a macropatch electrode while the subterminal axon branch was depolarized by current passed through an intracellular microelectrode. For depolarizing currents of moderate size, the latency of transmitter release did not change when the duration of the depolarizing current was altered. Previous studies in which a contrary result was obtained may have been compromised by artefacts or by the sampling methods employed. The present results do not support the hypothesis of a depolarization-induced "repressor" of quantal release.

scholarly journals Морфо-функціональна будова нейром’язових з’єднань жувального м’яза щура в нормі.

2017 ◽  
Author(s):  
A. O. Hrad
Keyword(s):  
Neuromuscular Junction ◽  
Neuromuscular Junctions ◽  
Nerve Impulse ◽  
High Sensitivity ◽  
Masticatory Muscles ◽  
Low Noise ◽  
Male Rats ◽  
Synaptic Membrane ◽  
Neuromuscular Synapses ◽  
Morphological Studies

A number of studies indicate that synaptoarchitectonics in mature skeletal muscles is characterized by considerable variability and largely depends on the function of the muscle and the phenotype of muscle fi bers. However, quantitative and qualitative morphological studies of neuromuscular synapses of the rat chewing muscle remained outside the fi eld of view of the researchers.The aim of the study – to establish the features of the morphofunctional structure of the neuromuscular junction of the rat’s masseter in norm.Materials and Methods. The material for the study was the masticatory muscles of 10 mature male rats of the Wistar line (body weight 180–200 g). To detect neuromuscular junctions, the chewing muscles were fi xed for 25–30 days in 12 % neutral formalin. The material was washed and made a cut of 30–40 μm thick in a cryostat, which were processed by the Bilshowski-Gros method. For electronic research, the sampling was carried out according to generally accepted rules. Pieces of muscle fi bers were fi xed in a 2 % solution of osmium tetroxides, and contrasting according to the conventional method. Stimulation and interference electroneuromyography was performed on Neuro-EMG-Micro computer Neur EMG micro microcomputer manufactured by Neurosoft Company (Russia), which has low noise level, high sensitivity (10–500 μV / cm) and resistance to distortion. Computer processing of data was carried out using statistical package Stat.Soft.Inc; Tulsa, OK, USA; Statistica 6.Results and Discussion. In the masticatory muscle, neuromuscular junctions have their synaptoarchitectonics, which are characterized by: scouting of the motor axon, length and width of the active zones, the number and size of synaptic folds, the number of neurolematocytes, the peculiarity of the structure of the spinal-protective membrane. The area of the neuromuscular junction is (385.74 ± 16.63) μm 2. The neuromuscular junction includes several neuromuscular synapses, which have the following quantitative characteristics: area – (6.23 ± 1.03) μm2, the length of the synaptic junction is (2.56 ± 0.52) μm, the number of folds of the synaptic membrane is 8.6 ± 0.69, the distance between the folds is – (0.35 ± 0.002) μm, the length of the individual fold is (3.31 ± 0.03), the number of synaptic vesicles is (172.69 ± 16.03).Conclusions. Electro neuromyographic studies of masticatory muscles indicate the correct direction of nerve impulse transmission, high amplitude characteristics of excitation transfer and M-response in case of single stimulation.

Denervation, Reinnervation, and Regeneration of Skeletal Muscle

1981 ◽  
Vol 89 (2) ◽  
pp. 192-196 ◽  
Author(s):  
Bruce M. Carlson
Keyword(s):  
Skeletal Muscle ◽  
Neuromuscular Junction ◽  
Functional Ability ◽  
De Novo ◽  
Neuromuscular Junctions ◽  
Original Structure ◽  
De Novo Synthesis ◽  
Regenerative Capacity ◽  
Neuromuscular Synapses ◽  
Motor End Plate

This paper reviews the responses of skeletal muscle tissue to denervation, with emphasis on the area of neuromuscular junction. In reinnervation, neuromuscular synapses are formed preferentially at the site of the old motor end plate, but the de novo synthesis of new neuromuscular junctions is possible. Skeletal muscle has a good regenerative capacity, and a regenerating muscle fiber can, essentially, return to original structure and functional ability.

Changes in flowering and the accumulation of polyamines and hydroxycinnamic acid-polyamine conjugates in tobacco plants transformed by the rolA locus from the Ri TL-DNA of Agrobacterium rhizogenes

Plant Science ◽  
1991 ◽  
Vol 80 (1-2) ◽  
pp. 145-156 ◽  
Author(s):  
Li-Yan Sun ◽  
Marie-Odile Monneuse ◽  
Josette Martin-Tanguy ◽  
David Tepfer
Keyword(s):  
Agrobacterium Rhizogenes ◽  
Hydroxycinnamic Acid ◽  
Tobacco Plants ◽  
Polyamine Conjugates
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