Restorative Neurology and Neuroscience - Volume 1, issue 3-4

Authors: Burgoyne, Robert D. | Robson, Susanne J.

Article Type: Research Article

Abstract: The expression and distribution of β-tubulin gene products and post-translationally modified forms of α-tubulin in dorsal root ganglion neurons in culture were examined. The neurons in culture rapidly regenerated neurites and expressed multiple β-tubulin genes (Mβ2, Mβ3/4, Mβ5, Mβ6). The gene products were present in the neurites and growth cones. Unmodified tyrosinated α-tubulin was present in the neurites and growth cones but modified α-tubulins (detyrosinated and acetylated) were largely absent from growth cones. The distribution of the α-tubulin forms is consistent with assembly of tubulin occurring behind the growth cone after transport of non-polymeric subunits. Distal assembly of microtubules would …provide a pool of unmodified α-tubulin subunits for the assembly of labile microtubules in the growth cone. Subsequent modification behind the advancing growth cone would stabilise the newly formed neurite. Show more

Keywords: Tubulin, Microtubules, Dorsal root ganglion

DOI: 10.3233/RNN-1990-13401

Citation: Restorative Neurology and Neuroscience, vol. 1, no. 3-4, pp. 173-177, 1990

Authors: Cancalon, Paul F.

Article Type: Research Article

Abstract: The composition and organization of the axonal cytoskeleton vary from neuron to neuron and the ability of a nerve to regenerate may, at least in part, depend on the pre-existing nature of the cytoskeleton. In axons, where the cytoskeletal elements are loosely organized enough material may be mobilized after an injury to allow elongation to proceed. However, if microtubules and neurofilaments interact closely with each other, it may not be possible for enough material to be released from or to migrate through a complex network. As a consequence material is not provided to the growing tip and elongation cannot proceed …beyond the initial sprouting. Show more

Keywords: Cytoskeleton, NFs, MTs, Cytoskeletal interactions, Elongation velocity

DOI: 10.3233/RNN-1990-13402

Citation: Restorative Neurology and Neuroscience, vol. 1, no. 3-4, pp. 179-187, 1990

Authors: Tetzlaff, W. | Bisby, M.A.

Article Type: Research Article

Abstract: Following injury to the facial nerve, facial motoneurons respond with a rapid suppression of neurofilament synthesis, and an increase in actin and tubulin synthesis. In situ hybridization studies show that these changes are the result of alterations in levels of the corresponding mRNAs. The increased ratio of neurofilament to tubulin expression is also characteristic of developing neurons, and direct evidence for the idea that axon injury provokes a partial return to a developmental state is provided by the finding that there is rapid re-expression of a developmentally regulated α-tubulin gene. In magnocellular rubrospinal neurons, whose axons do not regenerate after …injury, the same initial changes in gene expression occurred, but they were not sustained. We do not know whether this is cause or effect of the failure to regenerate, but we can conclude that injured CNS neurons have the potential to respond to injury by initiating a ‘regeneration programme’. Failure to sustain this programme is presumably due to differences in the trophic environment of central and peripheral axons. Show more

Keywords: Cytoskeleton, Regeneration, Cell body reaction, Rubrospinal neurons

DOI: 10.3233/RNN-1990-13403

Citation: Restorative Neurology and Neuroscience, vol. 1, no. 3-4, pp. 189-196, 1990

Authors: Wilson, David L. | Perry, G.W.

Article Type: Research Article

Abstract: We review evidence related to several hypotheses concerning the mechanism of axon regeneration and present new data addressing one hypothesis. That one hypothesis concerns the signal that initiates changes in the cell bodies of neurons after axon damage. We identify a molecule that has a number of the properties expected of such a signal. We also review the hypothesis that induction of some genes is tightly correlated with nerve regeneration, and conclude that such a correlation is not so ‘tight’. Nevertheless, proteins whose rate of synthesis or transport is increased in some systems are good candidates for playing important roles …in regrowth. A third hypothesis, that mammalian CNS neurons fail to regenerate because of a failure to induce growth-associated proteins, is probably not true. Growth-associated proteins appear to be induced, at least transiently, in some cases where regeneration is abortive. The state of the neuron undoubtedly is important in regeneration, but many neurons, even in the CNS, appear to be able to support axon regrowth given the proper environment. Thus, support seems stronger for the view that the environment at the site of damage (including surfaces and growth factors) determines whether significant regrowth occurs in most cases. Show more

Keywords: Nerve regeneration, Axoplasmic transport, Proteins, Two-dimensional gels, Sciatic nerve, Axon growth, Growth-associated proteins

DOI: 10.3233/RNN-1990-13404

Citation: Restorative Neurology and Neuroscience, vol. 1, no. 3-4, pp. 197-203, 1990

Authors: Ishii, Douglas N.

Article Type: Research Article

Abstract: The mechanisms responsible for the formation, loss, and regeneration of vertebrate synapses are still shrouded in mystery. Recent data suggesting that insulin-like growth factor II (IGF-II) may play a special role in the nervous system are reviewed. In particular, studies now show that the IGF-II gene is selectively expressed in a manner consistent with its involvement in the formation of the neural circuitry. The prenatal up-regulation and postnatal down-regulation of IGF-II transcripts in muscle are closely correlated with the prenatal accumulation and postnatal elimination, respectively, of polyneuronal innervation at the neuromuscular junction. Use and disuse of nerve and muscle can …profoundly alter the developmental rate at which superfluous synapses are eliminated. Such alteration may result through modification of the rate at which postnatal down-regulation of IGF-II mRNA content occurs. Moreover, IGF-II mRNA content is correlated with the capacity of muscle to regenerate synapses. The IGF-II gene may be the first example of a gene which can regulate the development and turnover of vertebrate synapses. Show more

Keywords: Somatomedin, Neuromuscular junction, Synaptogenesis

DOI: 10.3233/RNN-1990-13405

Citation: Restorative Neurology and Neuroscience, vol. 1, no. 3-4, pp. 205-210, 1990

Authors: Kanje, Martin | Skottner, Anna | Sjöberg, Jacob

Article Type: Research Article

Abstract: We have found that insulin-like growth factor I (IGF-I) stimulates regeneration of the rat sciatic nerve. This paper reviews and adds some new data to our investigations on the effects of local administration of IGF-I to the sciatic nerve after infliction of a crush or freeze injury.

Keywords: Insulin-like growth factors, Somatomedins, Peripheral nerve, Sciatic nerve, Rat, Regeneration

DOI: 10.3233/RNN-1990-13406

Citation: Restorative Neurology and Neuroscience, vol. 1, no. 3-4, pp. 211-215, 1990

Authors: Raivich, Gennadij | Hellweg, Rainer | Graeber, Manuel B. | Kreutzberg, Georg W.

Article Type: Research Article

Abstract: Growth factors and their receptors play a central role in the regulation of normal and injury-induced regenerative cell growth. In this article we review the data on the expression of growth factor receptors for β-nerve growth factor, platelet-derived growth factor and serum transferrin during regeneration following peripheral nerve injury. Particular emphasis is put on the pathophysiological mechanisms leading to the expression of these growth factor receptors, their interaction with their respective ligands and their specific role in this regenerative process.

Keywords: Peripheral nerve regeneration, NGF receptor, PDGF receptor, Transferrin receptor, Schwann cell, Fibroblast

DOI: 10.3233/RNN-1990-13407

Citation: Restorative Neurology and Neuroscience, vol. 1, no. 3-4, pp. 217-223, 1990

Authors: Carlsen, Richard C. | De Leon, Marino | Tetzlaff, Wolfram | Parhad, Irma M. | Bisby, Mark A.

Article Type: Research Article

Abstract: We are interested in the role cyclic AMP may play as a mediator of growth factor-induced gene expression in regenerating peripheral nerves. As a first step, we investigated mRNA levels and protein synthesis in intact frog dorsal root ganglia (DRG) treated with the adenylate cyclase activator, forskolin in vitro. Forskolin (10−7 M) increased intraganglionic cyclic AMP concentration 3-fold within 40 min of application and maintained this concentration through 60 min, when the drug was withdrawn. Addition of forskolin to isolated DRG neurons for 1 h increased the incorporation of [3 H]leucine into TCA-insoluble material beginning 12 h after the …withdrawal of forskolin. Axonally transported labeled material was increased almost 2-fold by 12 h. The effect of forskolin could be blocked by the simultaneous addition of actinomycin D, but not if actinomycin D was added 1 h later. Northern and dot-blot analysis of RNA extracted from the treated ganglia indicated that an mRNA coding for an α-subunit of tubulin was increased by treatment with forskolin. 2D PAGE also demonstrated an increase in an α-subunit of tubulin. An increase in neuronal cyclic AMP appears to selectively increase the production of specific proteins and may contribute to the production of macromolecules involved in the initiation and stimulation of axonal regeneration. Show more

Keywords: Frog DRG, Protein synthesis, Cyclic AMP, Forskolin, Nerve regeneration

DOI: 10.3233/RNN-1990-13408

Citation: Restorative Neurology and Neuroscience, vol. 1, no. 3-4, pp. 225-232, 1990

Authors: Skottner, Anna | Kanje, Martin | Arrhenius-Nyberg, Vibeke | Lundborg, Göran

Article Type: Research Article

Abstract: Systemic administration of human growth hormone (hGH) to intact or hypophysectomized rats was found to stimulate regeneration of the crush-lesioned sciatic nerve. The IGF-I levels of serum of the treated rats did not correlate with regeneration of the nerve but hGH treatment increased the IGF-I content of the nerve. The results suggest that a GH-mediated increase of IGF-I in the sciatic nerve could be involved in the stimulatory effect of GH on neurite outgrowth.

Keywords: Human growth hormone, Insulin-like growth factors, Sciatic nerve, In vivo, Regeneration, Rats

DOI: 10.3233/RNN-1990-13409

Citation: Restorative Neurology and Neuroscience, vol. 1, no. 3-4, pp. 233-235, 1990

Authors: Gispen, W. H. | Boonstra, J. | De Graan, P. N. E. | Jennekens, F. G. I. | Oestreicher, A. B. | Schotman, P. | Schrama, L. H. | Verhaagen, J. | Margolis, F.L.

Article Type: Research Article

Abstract: The protein kinase C substrate B-50 is identical to the growth-associated protein GAP-43. Although as yet no causal relationship has been established between B-50/GAP-43 and neurite outgrowth, evidence accumulates that the function of the protein relates to neuronal plasticity. Stimulation of PC12 cells by NGF results in translocation of the protein from cytosolic stores to the membrane of newly formed neurite-like extensions. The protein is associated with the inner leaflet of the growth cone membrane isolated from neonatal rat brain and was used as a marker to study the development of the rat pyramidical tract and olfactory system. In the …adult rat, crush lesion of the sciatic nerve results in a rapid expression of B-50/GAP-43 mRNA followed by synthesis of B-50/GAP-43 protein in dorsal root ganglia and transport of the protein into the newly formed sprouts. Presumably, the neurotrophic effect of melanocortins on peripheral nerve repair is not brought about by enhancement of B-50/GAP-43 synthesis per se. Bulbectomy (central) or Triton X-100 lesioning (peripheral) of the olfactory epithelium results in a differential expression of B-50/GAP-43 and the olfactory marker protein characterizing two stages in the regeneration of this epithelium. Evidence that the degree of phosphorylation may co-determine the role of B-50/GAP-43 in neurite outgrowth is discussed. Show more

Keywords: B-50/GAP-43, Axonal regeneration, Neuronal development, Sciatic nerve, Pyramidal tract, Olfactory system, Melanocortins, Protein kinase C

DOI: 10.3233/RNN-1990-13410

Citation: Restorative Neurology and Neuroscience, vol. 1, no. 3-4, pp. 237-244, 1990

Authors: Ingoglia, N.A. | Chakraborty, G. | Yu, M. | Luo, D. | Liu, C.

Article Type: Research Article

Abstract: Both axonal and glial components of nerve are capable of carrying out reactions in which Arg, Lys, Leu, Pro, Val, AJa and Ser can be covalently linked to endogenous proteins in reactions which require tRNA but occur in the absence of ribosomes and ribosomal RNA. These posttranslational protein modifications appear to play important roles in nerve regeneration since they are increased more than 10-fold within 2 h of a crush injury in nerves which are capable of regeneration, but are not activated in nerves not capable of regrowth following injury. The regulation of the modification of proteins by Arg and …Lys in vivo appears to be the function of separate peptides. The exogenous application of serine protease inhibitors (but not other protease inhibitors) mimics the effect of the endogenous peptides, suggesting that the endogenous regulators have serine protease inhibitory activity. The targets for modification are proteins of low abundance and thus far have been identified only in terms of their molecular weights and isoelectric points. The site of addition of Arg, but not the other amino acids, to target proteins is to the amino terminus. The addition of Arg to an amino terminus is likely to be involved in the ubiquitin mediated proteolysis of the modified protein. One of the most unusual findings in these series of experiments is that in regenerating sciatic nerves, amino acid modified proteins aggregate to form complexes of greater than 2 × 106 Da. The significance of this finding is not known. But we speculate that the aggregate may result from the assembly of an insoluble functional unit of the cell from soluble precursor proteins, and that the trigger for their assembly is amino acid modification. Show more

Keywords: Posttranslational modification, Amino acid, Sciatic nerve, Regeneration, tRNA

DOI: 10.3233/RNN-1990-13411

Citation: Restorative Neurology and Neuroscience, vol. 1, no. 3-4, pp. 245-252, 1990

Authors: Danielsen, Nils

Article Type: Research Article

Abstract: The silicone nerve regeneration chamber is a useful model to investigate the cellular and molecular events underlying successful regeneration in the peripheral nervous system. In this model a transected rat sciatic nerve with a 10-mm interstump gap, is repaired with a silicone chamber. The spatial-temporal sequence of regeneration in the silicone chamber has been examined in detail. The chamber rapidly becomes filled with fluid which contains neurotrophic activity for neurons in vitro. The second event to occur is the formation of a fibrin matrix connecting the two nerve stumps. This matrix is then invaded by cellular elements in the following …order: perineurial-like cells, vasculature, Schwann cells, and axons. The silicone chamber model also allows manipulation of the regeneration process. Prefilling the chamber at the time of implantation with phosphate-buffered saline or dialyzed plasma stimulates nerve regeneration. Multiple injections into the chamber of a mixture containing laminin, testosterone, and ganglioside GM1 increase the size and the vascularization of the regenerate. Specially designed chambers divided into two compartments by a longitudinally inserted nitrocellulose strip have been used to examine the effects of substrate-bound trophic factors on nerve regeneration. Fibroblast growth factor containing chambers have an improved regeneration and vascularization as compared to controls. Show more

Keywords: Silicone chamber, Nerve regeneration, Rat sciatic nerve, Neurotrophic factors, Fibrin matrix, Fibroblast growth factor

DOI: 10.3233/RNN-1990-13412

Citation: Restorative Neurology and Neuroscience, vol. 1, no. 3-4, pp. 253-259, 1990

Authors: Edström, Anders | Edbladh, Magnus | Ekström, Per | Remgård, Pär

Article Type: Research Article

Abstract: The adult frog sciatic nerve offers several advantages as an in vitro model to study nerve regeneration. The nerve with the attached dorsal root ganglia can easily be isolated and incubated in a culture medium for several days. If the nerve is subjected to a crush immediately after dissection there is a delay of 3.4 days after which the sensory axons start to regenerate into the distal nerve stump at a constant rate of about 1.1 mm · day−1 in serum-containing and 1.0 mm · day−1 in serum-free medium. Serum-free cultures may be used in future studies to …examine the effect of various neurotrophic factors. The existence of an accurate method for examining the outgrowth distance, based on axonal transport of labelled proteins, contributes to the attractiveness of the model. A compartmental culture system permits separate exposure of the ganglia and the nerve to different agents. Taking advantage of this, pharmacological studies suggest that Schwann cells produce signals, dependent on newly transcribed RNA, which transform the preparation into a growth state. The present model system offers favourable conditions to learn more about the early events and also the subsequent steps of the regeneration process. Show more

Keywords: Nerve regeneration, Sciatic nerve, In vitro, Adult frog

DOI: 10.3233/RNN-1990-13413

Citation: Restorative Neurology and Neuroscience, vol. 1, no. 3-4, pp. 261-266, 1990

Authors: Tonge, D. A. | Clarke, J. D. W. | Hunter, K. | Golding, J.

Article Type: Research Article

Abstract: Peripheral nerves and spinal cords of axolotls were maintained in organ culture for periods of up to 2 weeks. Sensory axons in peripheral nerves and the dorsal funiculus of the spinal cord showed regeneration through the crush site within about 2 days. Axonal regeneration also occurred in peripheral nerves after cutting but was dependent on close contact between proximal and distal stumps of nerve. When cells in the distal stump of nerve were killed by freezing, axonal regeneration was inhibited.

Keywords: Peripheral nerve, Spinal cord, Nerve regeneration

DOI: 10.3233/RNN-1990-13414

Citation: Restorative Neurology and Neuroscience, vol. 1, no. 3-4, pp. 267-273, 1990

Authors: Aldskogius, Håkan | Molander, Carl

Article Type: Research Article

Abstract: There are indications that specific factors are present in the distal stump of transected nerves which preferentially attract axons of the corresponding proximal stump into the distal nerve stumps. However, the impact of these factors is unclear, since there is abundant evidence that numerous regenerating motor and sensory axons are topographically misdirected after nerve transection and repair. Topographic reinnervation is improved after fascicular repair of fasciculated nerves, and quite precise after nerve crush. The latter may not be true, however, for non-myelinated axons, which show a high degree of aberrant growth even after crush. In contrast, regenerative outgrowth appears to …be topographically specific after neonatal nerve transection. Reinnervation of muscle fibers appears to be unspecific in adult mammals, but specific after neonatal injury under certain circumstances. Some preference for reinnervation of the appropriate sensory receptors seems to exist although this preference does not preclude reinnervation of receptors by ‘foreign’ sensory fibers. In conclusion, incorrect topographic and target reinnervation commonly occurs after peripheral regeneration in adult mammals, and most certainly explains some of the functional disturbances after peripheral nerve lesions. Topographic regeneration appears to be better after nerve injury in developing mammals indicating that mechanisms from the developmental period may persist and aid in accurate regenerative outgrowth. Show more

Keywords: Regeneration, Motor, Sensory, Adult, Development, Myelinated axon, Non-myelinated axon

DOI: 10.3233/RNN-1990-13415

Citation: Restorative Neurology and Neuroscience, vol. 1, no. 3-4, pp. 275-280, 1990

Authors: Brushart, Thomas M. E.

Article Type: Research Article

Abstract: Previous experiments have shown that motor axons regenerating in mixed nerve will preferentially reinnervate a distal motor branch. The present experiments examine the mechanism through which this sensory-motor specificity is generated. An enclosed 0.5 mm gap was created in the proximal femoral nerves of juvenile rats. Two, three or eight weeks later the specificity of motor axon regeneration was evaluated by simultaneous application of horseradish peroxidase (HRP) to one distal femoral branch (sensory or motor) and Fluoro-Gold to the other. Motoneurons were then counted as projecting (i) correctly to the motor branch, (ii) incorrectly to the sensory branch, and (iii) …simultaneously to both branches (double-labeled). Motor axon regeneration was random at 2 weeks, with equal numbers of motoneurons projecting to sensory and motor branches. However, the number of correct projections increased dramatically between 2 and 3 weeks. Twenty-six percent of neurons labeled at 2 weeks contained both tracers, indicating axon collateral projections to both sensory and motor branches. This number decreased significantly at each time period. Axon collaterals were thus ‘pruned’ from the sensory branch, increasing the number of correct projections at the expense of double-labeled neurons. These findings suggest random reinnervation of the distal stump, with specificity generated through trophic interaction between axons and the pathway and/or end organ. Show more

Keywords: Regeneration, Peripheral nerve, Neurotrophism, Double labeling, Axon collaterals, Selective pruning

DOI: 10.3233/RNN-1990-13416

Citation: Restorative Neurology and Neuroscience, vol. 1, no. 3-4, pp. 281-287, 1990

Authors: Carlstedt, T. | Risling, M. | Lindå, H. | Cullheim, S. | Ulfhake, B. | Sjögren, A. M.

Article Type: Research Article

Abstract: Spinal nerve root avulsion has been considered as a central nervous type of injury and therefore not repaired surgically in man. The possibility for axonal regeneration after root avulsion or root lesion has been investigated in laboratory animals by means of up to date neurophysiological, morphological and tracing techniques. It is shown that, after ventral root avulsion and implantation into the spinal cord, alpha and probably also gamma motoneurons are able to regenerate within the spinal cord for a considerable distance before entering the implanted root and reinnervate previously denervated skeletal muscles. The regenerated neurons were found to respond to …afferent activity with excitatory or inhibitory responses, and the regenerated axons could conduct action potentials that elicited muscle twitch responses. After dorsal root injury in the adult animal, regeneration into the spinal cord does not occur. However, regeneration of primary sensory neurons into appropriate locations of the spinal cord can be demonstrated in immature animals. Show more

Keywords: Spinal nerve root, Avulsion, Plexus injury, Neuron, Glia, Regeneration

DOI: 10.3233/RNN-1990-13417

Citation: Restorative Neurology and Neuroscience, vol. 1, no. 3-4, pp. 289-295, 1990

Authors: Lundborg, Göran

Article Type: Research Article

Abstract: Injuries to peripheral nerves represent a challenging clinical problem. In spite of the use of microsurgical techniques, repair of severed nerves seldom results in complete recovery of motor and sensory functions. Misdirection of axons at the suture line as well as a slow axonal outgrowth contribute to the bad results. Recent experimental data indicate that growth factors, synthesized by the damaged nerve tissue as well as protein-associated neurite-promoting factors in the local micro-environment play an important role for the regulation of axonal growth and directionality. Future studies should aim at an application of this knowledge to the clinical treatment of …nerve injuries. Show more

Keywords: Peripheral nerve, Nerve injury, Nerve repair, Nerve regeneration, Growth factors, Schwann cells

DOI: 10.3233/RNN-1990-13418

Citation: Restorative Neurology and Neuroscience, vol. 1, no. 3-4, pp. 297-302, 1990

Authors: Sisken, Betty F. | Kanje, Martin | Lundborg, Göran | Kurtz, Warren

Article Type: Research Article

Abstract: The influence of non-invasive, low level, pulsed electromagnetic fields (PEMF) on regeneration was tested on in vitro and in vivo models. Cultures of dorsal root ganglia were exposed to 2 Hz PEMF, amplitude of 0.05 mTesla while rats after a ‘crush’ lesion of sciatic nerves were exposed to 2 Hz PEMF, amplitude of 0.3 mTesla. In in vitro experiments, relative to controls, cultures treated with PEMF exhibited a significant increase in neurite outgrowth with dense labeling of neurons and neurites on autoradiographs after incorporation of [3 H]proline into new proteins. In vivo exposure of rats to PEMF for 3, 4 …or 6 days after lesioning produced a 22% increase in the regeneration rate relative to controls with no effect on the initial delay period. When rats were exposed to PEMF before lesioning without further treatment, the same degree of stimulation of axonal sprouting was obtained. Reduction of the amplitude from 0.3 mTesla to 0.06 mTesla eliminated this pre-exposure response. Alterations in the distribution of new proteins synthesized 2 weeks after PEMF treatment provide additional evidence for its influence at the whole body and cellular levels. Show more

Keywords: Pulsed electromagnetic field, Sensory ganglia culture, Neurite outgrowth, Crush lesion, Pinch test, Protein synthesis

DOI: 10.3233/RNN-1990-13419

Citation: Restorative Neurology and Neuroscience, vol. 1, no. 3-4, pp. 303-309, 1990