Motor Nerve Regeneration Research Articles

Application of weak electric field to the hindpaw enhances sciatic motor nerve regeneration in the adult rat

Direct current (DC) electrical stimulation of the hindpaw is shown to enhance sciatic motor nerve regeneration in the adult rat. Cathodal stimulation, using weak currents (10 μA/cm 2; field strength approximately 100 m V/cm) increased the reinnervation of the hindpaw muscles as measured by evoked electromyograms. This enhanced regeneration only occured after cut-and-suture lesions, but not after crushing injury of the sciatic nerve. This enhancement of motor nerve regeneration by weak DC fields had been previously described in amphibians but we are the first to describe this phenomenon in mammals.

An in vivo model to quantify motor and sensory peripheral nerve regeneration using bioresorbable nerve guide tubes

An in vivo preparation is presented to study the rate and time course of motor and sensory axonal regeneration. The cut ends of a transected sciatic nerve were inserted into each end of a 5–6 mm non-toxic and bioresorbable nerve guide tube to create a 4 mm nerve gap in adult mice. Subsequently, cell bodies in the ventral spinal cord and L3–L5 dorsal root ganglia that had regenerated axons across the gap were retrogradely labeled with horseradish peroxidase (HRP). The HRP was applied 3 mm distal to the nerve guide and was accessible only to axons that had regenerated through the nerve guide. Labeled cells were counted in 40 μm serial sections at 2, 4 and 6 weeks after initial nerve transection. The results indicate a significant increase in the number of labeled motor and sensory cell bodies over time. By 6 weeks after transection, approximately two thirds as many ventral horn motor cells and one third as many dorsal root ganglion sensory cells were labeled as in control non-transected animals. These data serve as a baseline to compare differential effects of additives to the nerve guide lumen in terms of sensory and motor neuron response.

The effects of pyronin on sprouting and regeneration of mouse motor nerves

Administration to mice of a 0.1% solution of pyronin G in their drinking water caused an acceleration both of axonal sprouting from nodes of Ranvier in partly denervated gluteus maximus muscles, and of motor nerve regeneration following a crush to the soleus nerve. Sprouting from soleus motor nerve terminals in response to botulinum toxin-induced paralysis was, however, unaffected. Removal of degenerating axons following nerve section was also accelerated by pyronin treatment. Pyronin is therefore likely to act upon the process of Wallerian degeneration, rather than upon intact motor nerves directly.

Efficacy of triamcinolone acetonide following neurorrhaphy-an electroneuromyographic evaluation.

A primate model to test the effects of triamcinolone acetonide on reinnervation after neurorrhaphy was developed. Reinnervation was assessed in triamcinolone- and placebo-treated nerves. Twelve months after neurorrhaphy, nerves treated with triamcinolone had a faster conduction velocity; a greater amplitude in the evoked response; more and larger axons distally on cross-sectional histological examination; and an evoked response wave form closely resembling normal. We conclude that triamcinolone acetonide instilled locally about a neurorrhaphy immediately after the repair is beneficial for the regeneration of motor nerves in primates.

Interaction between motor axons from two different nerves reinnervating the pectoral muscle of Xenopus laevis.

1. An electrophysiological and morphological study of sprouting and regeneration of motor nerves has been performed in the dually innervated pectoral muscle of Xenopus laevis. 2. Section of one of the nerves induced axon sprouting in the intact nerve. Synapse formation by the sprouting axons was slow since the intact nerve took more than 3 months to increase its field of innervation by 70%. The rate of axon regeneration was faster than that of axon sprouting since the cut nerve reinnervated its former territory in less than 1 month. 3. At early stages of synapse formation the sprouted or regenerated endings were poorly branched but any terminal branches were, as a rule, longer than normal. Signs of degeneration and replacement of endings have been observed. 4. Low levels of transmitter release persisted for several months in newly formed endings. This depression was more pronounced at the endings formed outside the normal field of innervation of the nerve. 5. Poly-innervated muscle fibres have been observed during reinnervation by regenerated or sprouted axons. Their number decreases gradually in the months that follow the beginning of reinnervation. Synaptic efficacy was lower at poly than at mono-innervated muscle fibres. At doubly innervated spots and at separated spots on the same fibre average end-plate potential (e.p.p.) amplitude was 1/3 and 2/3 respectively of that recorded at singly innervated fibres. 6. Electrophysiological and morphological data have been compared at individual doubly innervated end-plate sites. End-plate potential amplitude was positively correlated with the degree of ending development. 7. Sprouted endings remain functional after periods of reinnervation of 30 months, although signs of regression have been observed. These are probably mediated by spontaneous degeneration of the terminals and replacement by endings from the regenerating nerve.

Regulation of polyamine biosynthesis

Thyroid hormones and spermidine, a motor neuron trophic polyamine (PA), have been shown to enhance peripheral motor nerve regeneration; however, the mechanism by which these treatment modalities exert their effect is unknown. Similarities in treatment outcome suggest that these molecules may be working via a common mechanism. Such an explanation is plausible since thyroid hormone is a potent inducer of ornithine decarboxylase (ODC), which is the rate-limiting enzyme involved in polyamine synthesis. This study was designed to morphologically evaluate the effects of exogenous thyroxine and spermidine on the regeneration of the rat facial nerve. Myelinated fiber density, axonal size, and degree of myelination were assayed by light and electron microscopy 21 days following facial nerve crush. Strikingly, the two treatment modalities had identical effects on all parameters tested. Each significantly enhanced the density of myelinated axons in regenerating nerves relative to the vehicle control. In addition, relative to the control treatment, both thyroxine and spermidine significantly increased the cross-sectional area of regenerating axons (P < 0.05). Interestingly, neither of the drug treatments had any effect on remyelination at the position where this parameter was analyzed. The concurrent administration of both thyroxine and spermidine did not synergistically enhance motor neuron regeneration. These data support the hypothesis that thyroxine and spermidine enhance neural regeneration by a common mechanism.

Action potentials in slow muscle fibres of the frog during regeneration of motor nerves.

1. Pyriformis muscles of Rana temporaria were denervated by crushing the sciatic nerve inside the pelvis. At different times during regeneration of the nerve, slow muscle fibres were examined for the presence of all-or-none responses. 2. During the early period of re-innervation (35-60 days), slow muscle fibres were found to be non-selectively re-innervated by (foreign) fast-conducting motor axons. All slow fibres during this period were able to produce full sized action potentials, with overshoot. 3. Action potentials markedly decreased in amplitude and eventually disappeared completely between day 61-110 following denervation; during this period, slow muscle fibres were re-innervated by slowly-conducting motor axons. 4. Functional re-innervation by slowly-conducting motor axons, in the late stages of re-innervation, was not a necessary condition for the suppression of the action potential. Slow fibres innervated by fast motor axons, as well as denervated slow fibres, lost the action potential simultaneously with slow fibres which were re-innervated by slowly-conducting motor axons. 5. It is suggested that (small) slowly-conducting motor axons can exert a 'trophic' influence on the slow fibre membrane, independent of their synaptic function.

Fast axonal transport in motor nerve regeneration.

This report describes the fast transport of [3H]-leucine-labeled proteins in regenerating rat sciatic motor nerves. A normal rate of fast transport (383 +/- 33 mm/day) was present in the regenerating sprouts, as well as in the central stumps. The rapidly transported proteins passed the level of axotomy without impediment, and accumulated in the endings of the regenerating sprouts, as shown by electron microscope autoradiography. In addition, transported proteins accumulated in terminal neuromas. The relative amount of protein-incorporated radioactivity in the crest of transport in the regenerating nerves was increased compared to control nerves. These results are interpreted to suggest that the mechanism of fast transport is the same in regenerating nerves was increased compared to control nerves. These results are interpreted to suggest that the mechanism of fast transport is the same in regenerating sprouts as in normal axons; during regeneration fast transport appears to add newly synthesized materials to the growing tip.

Ultrastructural correlates of motor nerve regeneration in crayfish.

Identified motor neurons innervating distal limb muscles in the crayfish claw have been examined by light and electron microscopy after surgical interruption. The functionally competent distal segments of such axons, a few weeks after the operation, show enlarged glial sheaths that contain occasional small satellite axonal profiles (cf. Nordlander and Singer, 1972); evidence is presented that such profiles can arise from sources other than the outgrowing central processes of motor axons. When functional connections are reestablished with the muscles in 100 days or less, multiple axon profiles are never seen in motor axon sheaths in the distal limb segments, though they may occur close to the operation site. In contrast, delayed regenerates (≥200 days) show multiple profiles all the way to the muscles, and the functional connections made are abnormal. We conclude that, although the multiple profiles may represent outgrowth filaments from the central motor axons, they do not normally reach the muscle in prompt regenerates. The results suggest that instead they fuse with the surviving distal axon segment.

Peripheral Nerve Regeneration

To the Editor— Rix's letter (217:480, 1971) recommending primary nerve repair in combined nerve and tendon lacerations, and the subsequent letters of Raskind et al (217:1864, 1971) and Cramer (219:1213, 1972) presented interesting discussions of the management of peripheral nerve injuries. We are in the process of reviewing data from a serial study 1 of 376 peripheral nerve injuries in 223 patients, and I would like to offer some preliminary observations and theoretical support for Rix's conclusions. Our study was prospective, and included a protocol in which clinical and electromyographic examinations were serially performed. In studying regeneration of motor nerves we found that even in the most successful cases when full clinical strength returned, innervation as determined electromyographically by counting motor units was less than complete. Apparently, following peripheral nerve injury, greater-than-normal numbers of muscle fibers become incorporated in each motor unit, and muscle fibers undergo hypertrophy. Similar studies of

Changes in axonal flow during regeneration of mammalian motor nerves.

Measurements of axonal diameters in regenerating facial nerves of rats indicated a loss of axonal volume of approximately 60% in 14 days. These measurements were made in the intramedullary genu of the facial nerve thus indicating that transection of the distal portion of the nerve produces marked changes throughout the length of the injured axons.

Growth of the Nervous System: Ciba Foundation Symposium.

This book brings 14 papers read at a Ciba Foundation Symposium held in London in June 1967 to our attention. In the first session the development of specific neuronal connections are studied in several model systems, for example, explants of central nervous tissue or in vitro cultures of dissociated embryonic retinal cells. Other authors study the regeneration of motor nerves, retinal neurons, or retinotectal pathways in amphibians after sectioning or transplantation experiments. At the second session the normal development of movement is discussed in two papers, one on the coordinated movements in the chick embryo during incubation and hatching, the other on the development of limb innervation in amphibians. The third session is centered on the role of chemically specific signals in the development of the nervous system. The properties of the nerve growth factor, the action of thyroid hormones on the maturation of various brain parts in tadpoles, and

Investigations on the nature of peripheral factors influencing the process of motor nerve regeneration.

Journal of Comparative NeurologyVolume 99, Issue 3 p. 561-597 Article Investigations on the nature of peripheral factors influencing the process of motor nerve regeneration Daxiel Herbert Lodwick Evans, Daxiel Herbert Lodwick Evans Department of Anatomy, University College, LondonSearch for more papers by this author Daxiel Herbert Lodwick Evans, Daxiel Herbert Lodwick Evans Department of Anatomy, University College, LondonSearch for more papers by this author First published: December 1953 https://doi.org/10.1002/cne.900990306Citations: 11AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Citing Literature Volume99, Issue3December 1953Pages 561-597 RelatedInformation

Experiments on Motor Nerve Regeneration and the Direct Neurotization of Paralyzed Muscles by Their Own and by Foreign Nerves

Experiments on Motor Nerve Regeneration and the Direct Neurotization of Paralyzed Muscles by Their Own and by Foreign Nerves