scholarly journals The role of repulsive guidance molecules in the embryonic and adult vertebrate central nervous system

2006 ◽  
Vol 361 (1473) ◽  
pp. 1513-1529 ◽  
Author(s):  
Bernhard K Mueller ◽  
Toshihide Yamashita ◽  
Gregor Schaffar ◽  
Reinhold Mueller
Keyword(s):  
Neural Network ◽  
Central Nervous System ◽  
Nervous System ◽  
Synapse Formation ◽  
Neurite Growth ◽  
Local Environment ◽  
Growth Cones ◽  
Guidance Cues ◽  
Growth Guidance ◽  
Guidance Molecules

During the development of the nervous system, outgrowing axons often have to travel long distances to reach their target neurons. In this process, outgrowing neurites tipped with motile growth cones rely on guidance cues present in their local environment. These cues are detected by specific receptors expressed on growth cones and neurites and influence the trajectory of the growing fibres. Neurite growth, guidance, target innervation and synapse formation and maturation are the processes that occur predominantly but not exclusively during embryonic or early post-natal development in vertebrates. As a result, a functional neural network is established, which is usually remarkably stable. However, the stability of the neural network in higher vertebrates comes at an expensive price, i.e. the loss of any significant ability to regenerate injured or damaged neuronal connections in their central nervous system (CNS). Most importantly, neurite growth inhibitors prevent any regenerative growth of injured nerve fibres. Some of these inhibitors are associated with CNS myelin, others are found at the lesion site and in the scar tissue. Traumatic injuries in brain and spinal cord of mammals induce upregulation of embryonic inhibitory or repulsive guidance cues and their receptors on the neurites. An example for embryonic repulsive directional cues re-expressed at lesion sites in both the rat and human CNS is provided with repulsive guidance molecules, a new family of directional guidance cues.

scholarly journals Multiplexed neurochemical transmission emulated using a dual-excitatory synaptic transistor

2021 ◽  
Vol 5 (1) ◽  
Author(s):  
Mingxue Ma ◽  
Yao Ni ◽  
Zirong Chi ◽  
Wanqing Meng ◽  
Haiyang Yu ◽  
...  
Keyword(s):  
Neural Network ◽  
Central Nervous System ◽  
Nervous System ◽  
Long Term Potentiation ◽  
Short Term ◽  
Term Potentiation ◽  
Binary Neural Network ◽  
Neuromorphic Systems ◽  
Human Brains

AbstractThe ability to emulate multiplexed neurochemical transmission is an important step toward mimicking complex brain activities. Glutamate and dopamine are neurotransmitters that regulate thinking and impulse signals independently or synergistically. However, emulation of such simultaneous neurotransmission is still challenging. Here we report design and fabrication of synaptic transistor that emulates multiplexed neurochemical transmission of glutamate and dopamine. The device can perform glutamate-induced long-term potentiation, dopamine-induced short-term potentiation, or co-release-induced depression under particular stimulus patterns. More importantly, a balanced ternary system that uses our ambipolar synaptic device backtrack input ‘true’, ‘false’ and ‘unknown’ logic signals; this process is more similar to the information processing in human brains than a traditional binary neural network. This work provides new insight for neuromorphic systems to establish new principles to reproduce the complexity of a mammalian central nervous system from simple basic units.

scholarly journals Glioblastoma infiltration into central nervous system tissue in vitro: involvement of a metalloprotease.

1988 ◽  
Vol 107 (6) ◽  
pp. 2281-2291 ◽  
Author(s):  
P A Paganetti ◽  
P Caroni ◽  
M E Schwab
Keyword(s):  
Central Nervous System ◽  
Nervous System ◽  
White Matter ◽  
Optic Nerve ◽  
Cell Attachment ◽  
Neurite Growth ◽  
Cell Spreading ◽  
C6 Cells ◽  
3T3 Fibroblasts

Differentiated oligodendrocytes and central nervous system (CNS) myelin are nonpermissive substrates for neurite growth and for cell attachment and spreading. This property is due to the presence of membrane-bound inhibitory proteins of 35 and 250 kD and is specifically neutralized by monoclonal antibody IN-1 (Caroni, P., and M. E. Schwab. 1988. Neuron. 1:85-96). Using rat optic nerve explants, CNS frozen sections, cultured oligodendrocytes or CNS myelin, we show here that highly invasive CNS tumor line (C6 glioblastoma) was not inhibited by these myelin-associated inhibitory components. Lack of inhibition was due to a specific mechanism as the metalloenzyme blocker 1,10-phenanthroline and two synthetic dipeptides containing metalloprotease-blocking sequences (gly-phe, tyr-tyr) specifically impaired C6 cell spreading on CNS myelin. In the presence of these inhibitors, C6 cells were affected by the IN-1-sensitive inhibitors in the same manner as control cells, e.g., 3T3 fibroblasts or B16 melanomas. Specific blockers of the serine, cysteine, and aspartyl protease classes had no effect. C6 cell spreading on inhibitor-free substrates such as CNS gray matter, peripheral nervous system myelin, glass, or poly-D-lysine was not sensitive to 1,10-phenanthroline. The nonpermissive substrate properties of CNS myelin were strongly reduced by incubation with a plasma membrane fraction prepared from C6 cells. This reduction was sensitive to the same inhibitors of metalloproteases. In our in vitro model for CNS white matter invasion, cell infiltration of optic nerve explants, which occurred with C6 cells but not with 3T3 fibroblasts or B16 melanomas, was impaired by the presence of the metalloprotease blockers. These results suggest that C6 cell infiltrative behavior in CNS white matter in vitro occurs by means of a metalloproteolytic activity, which probably acts on the myelin-associated inhibitory substrates.

Neurotrophins affect the pattern of DRG neurite growth in a bioassay that presents a choice of CNS and PNS substrates

Development ◽  
1995 ◽  
Vol 121 (5) ◽  
pp. 1301-1309 ◽  
Author(s):  
R. Tuttle ◽  
W.D. Matthew
Keyword(s):  
Spinal Cord ◽  
Central Nervous System ◽  
Nervous System ◽  
Sciatic Nerve ◽  
Sympathetic Neurons ◽  
Neurite Growth ◽  
Drg Neurons ◽  
Substrate Preferences

Neurons can be categorized in terms of where their axons project: within the central nervous system, within the peripheral nervous system, or through both central and peripheral environments. Examples of these categories are cerebellar neurons, sympathetic neurons, and dorsal root ganglion (DRG) neurons, respectively. When explants containing one type of neuron were placed between cryosections of neonatal or adult sciatic nerve and neonatal spinal cord, the neurites exhibited a strong preference for the substrates that they would normally encounter in vivo: cerebellar neurites generally extended only on spinal cord, sympathetic neurites on sciatic nerve, and DRG neurites on both. Neurite growth from DRG neurons has been shown to be stimulated by neurotrophins. To determine whether neurotrophins might also affect the substrate preferences of neurites, DRG were placed between cryosections of neonatal spinal cord and adult sciatic nerve and cultured for 36 to 48 hours in the presence of various neurotrophins. While DRG cultured in NGF-containing media exhibited neurite growth over both spinal cord and sciatic nerve substrates, in the absence of neurotrophins DRG neurites were found almost exclusively on the CNS cryosection. To determine whether these neurotrophin-dependent neurite patterns resulted from the selective survival of subpopulations of DRG neurons with distinct neurite growth characteristics, a type of rescue experiment was performed: DRG cultured in neurotrophin-free medium were fed with NGF-containing medium after 36 hours in vitro and neurite growth examined 24 hours later; most DRG exhibited extensive neurite growth on both peripheral and central nervous system substrates.(ABSTRACT TRUNCATED AT 250 WORDS)

scholarly journals Non-viral Vector Mediated RNA Interference Technology for Central Nervous System Injury

2016 ◽  
Vol 3 (1) ◽  
Author(s):  
Christian Macks ◽  
Jeoung Soo Lee
Keyword(s):  
Central Nervous System ◽  
Nervous System ◽  
Rna Interference ◽  
Axonal Regeneration ◽  
Viral Vector ◽  
Traumatic Injury ◽  
Neurite Growth ◽  
Cns Injury ◽  
Growth Inhibitory ◽  
Inhibitory Molecules

AbstractNeuronal axons damaged by traumatic injury are unable to spontaneously regenerate in the mammalian adult central nervous system (CNS), causing permanent motor, sensory, and cognitive deficits. Regenerative failure in the adult CNS results from a complex pathology presenting multiple barriers, both the presence of growth inhibitors in the extrinsic microenvironment and intrinsic deficiencies in neuronal biochemistry, to axonal regeneration and functional recovery. There are many strategies for axonal regeneration after CNS injury including antagonism of growth-inhibitory molecules and their receptors, manipulation of cyclic nucleotide levels, and delivery of growth-promoting stimuli through cell transplantation and neurotrophic factor delivery. While all of these approaches have achieved varying degrees of improvement in plasticity, regeneration, and function, there is no clinically effective therapy for CNS injury. RNA interference technology offers strategies for improving regeneration by overcoming the aspects of the injured CNS environment that inhibit neurite growth. This occurs through the knockdown of growth-inhibitory molecules and their receptors. In this review, we discuss the current state of RNAi strategies for the treatment of CNS injury based on non-viral vector mediated delivery.

scholarly journals Prediction and Value of Ultrasound Image in Diagnosis of Fetal Central Nervous System Malformation under Deep Learning Algorithm

2021 ◽  
Vol 2021 ◽  
pp. 1-7
Author(s):  
Yuehong Zhou
Keyword(s):  
Neural Network ◽  
Central Nervous System ◽  
Nervous System ◽  
Deep Learning ◽  
Ultrasound Examination ◽  
Ultrasound Image ◽  
Control Group ◽  
Test Results ◽  
Experimental Group ◽  
Central Nervous System Malformation

This study was to explore the application of deep learning neural network (DLNN) algorithms to identify and optimize the ultrasound image so as to analyze the effect and value in diagnosis of fetal central nervous system malformation (CNSM). 63 pregnant women who were gated in the hospital were suspected of being fetal CNSM and were selected as the research objects. The ultrasound images were reserved in duplicate, and one group was defined as the control group without any processing, and images in the experimental group were processed with the convolutional neural network (CNN) algorithm to identify and optimize. The ultrasound examination results and the pathological test results before, during, and after the pregnancy were observed and compared. The results showed that the test results in the experimental group were closer to the postpartum ultrasound and the results of the pathological result, but the results in both groups showed no statistical difference in contrast to the postpartum results in terms of similarity ( P > 0.05 ). In the same pregnancy stage, the ultrasound examination results of the experimental group were higher than those in the control group, and the contrast was statistically significant ( P < 0.05 ); in the different pregnancy stages, the ultrasound examination results in the second trimester were more close to the postpartum examination results, showing statistically obvious difference ( P < 0.05 ). In conclusion, ultrasonic image based on deep learning was higher in CNSM inspection; and ultrasonic technology had to be improved for the examination in different pregnancy stages, and the accuracy of the examination results is improved. However, the amount of data in this study was too small, so the representative was not high enough, which would be improved.

scholarly journals Growth cone guidance and neuron morphology on micropatterned laminin surfaces

1993 ◽  
Vol 105 (1) ◽  
pp. 203-212 ◽  
Author(s):  
P. Clark ◽  
S. Britland ◽  
P. Connolly
Keyword(s):  
Growth Cone ◽  
Morphological Differentiation ◽  
Local Environment ◽  
Growth Cones ◽  
Dorsal Root Ganglion Neurons ◽  
Neuron Morphology ◽  
Neurite Extension ◽  
Guidance Cues ◽  
Cone Morphology ◽  
Ganglion Neurons

Neurite growth cones detect and respond to guidance cues in their local environment that determine stereotyped pathways during development and regeneration. Micropatterns of laminin (which was found to adsorb preferentially to photolithographically defined hydrophobic areas of micropatterns) were here used to model adhesive pathways that might influence neurite extension. The responses of growth cones were determined by the degree of guidance of neurite extension and also by examining growth cone morphology. These parameters were found to be strongly dependent on the geometry of the patterned laminin, and on neuron type. Decreasing the spacing of multiple parallel tracks of laminin alternating with non-adhesive tracks, resulted in decreased guidance of chick embryo brain neurons. Single isolated 2 microns tracks strongly guided neurite extension whereas 2 microns tracks forming a 4 microns period multiple parallel pattern did not. Growth cones appear to be capable of bridging the narrow non-adhesive tracks, rendering them insensitive to the smaller period multiple parallel adhesive patterns. These observations suggest that growth cones would be unresponsive to the multiple adhesive cues such as would be presented by oriented extracellular matrix or certain axon fascicle structures, but could be guided by isolated adhesive tracks. Growth cone morphology became progressively simpler on progressively narrower single tracks. On narrow period multiple parallel tracks (which did not guide neurite extension) growth cones spanned a number of adhesive/non-adhesive tracks, and their morphology suggests that lamellipodial advance may be independent of the substratum by using filopodia as a scaffold. In addition to acting as guidance cues, laminin micropatterns also appeared to influence the production of primary neurites and their subsequent branching. On planar substrata, dorsal root ganglion neurons were multipolar, with highly branched neurite outgrowth whereas, on 25 microns tracks, neurite branching was reduced or absent, and neuron morphology was typically bipolar. These observations indicate the precision with which growth cone advance may be controlled by substrata and suggest a role for patterned adhesiveness in neuronal morphological differentiation, but also highlight some of the limitations of growth cone sensitivity to substratum cues.

Use of calcium imaging technologies to dissect mechanisms underlying neuronal growth cone responses to environmental cues

1995 ◽  
Vol 53 ◽  
pp. 804-805
Author(s):  
C.V. Williams ◽  
S.B. Kater
Keyword(s):  
Nervous System ◽  
Growth Cone ◽  
Local Environment ◽  
Growth Cones ◽  
Neuronal Growth ◽  
Growth Inhibitory ◽  
Direct Growth ◽  
Neuronal Growth Cone ◽  
Mechanical Factors ◽  
Growth Promoting

Since calcium is a key second messenger in both the developmental formation and adult function of the nervous system, the ability to rapidly image changes in this molecule has added greatly to our understanding of how development of the nervous system is regulated. The nervous system is comprised of billions of neurons and glial cells that establish characteristic patterns of connections during development. Neurons extend processes that often must grow long distances to establish appropriate synaptic connections. Neurons perform a pathfinding behavior largely via the highly dynamic behavior of the neuronal growth cone at the distal tip of elongating processes. The motile behavior characteristic of growth cones allows the growth cone to survey the local environment, read local cues and respond to those cues with a change in behavior. A variety of cues are now known to direct growth cones (e.g. electrical activity, depolarization, growth factors, mechanical factors, neurotransmitters, substrate factors). This collection of factors includes both growth promoting and growth inhibitory influences.

Sign in / Sign up

Export Citation Format

Share Document