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Query: UMLS:C0599766 (functional recovery)
 13,441 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

For functional recovery after spinal cord injury, regenerating fibres need to grow and to reform appropriate connections with their targets. The isolated central nervous system of neonatal opossums aged 1-9 days has been used to analyse the precision with which neurons become reconnected during regeneration. In culture these preparations maintain their electrical activity and show rapid outgrowth through spinal cord crushes or cuts. By recording electrically and by staining with horseradish peroxidase, we first demonstrated that direct reflex connections were already present at birth between sensory fibres in one segment and motoneurons in the same segment and in adjacent segments. As in previous experiments, 5 days after the spinal cord had been crushed, labelled sensory fibres grew across the lesion to reach the next segment (Woodward et al. (1993) J. Exp. Biol., 176, 77-88; Varga et al. (1995a) Eur. J. Neurosci., 7, 2119-2129, Varga et al. (1995b) Proc. Natl. Acad. Sci. USA, 92, 10959-10963). Beyond the lesion the labelled axons abruptly changed direction, traversed the spinal cord and terminated on labelled motoneurons in the ventral horn. In preparations that had regenerated dorsal root stimulation once again initiated ventral root reflexes. Electron micrographs revealed synapses made by labelled sensory axons on motoneurons. Double staining of growing sensory axons and radial glial fibres showed close association, suggesting guidance. These results indicate that the original pathway is re-established during repair and that appropriate connections are reformed after injury.
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PMID:Re-establishment of direct synaptic connections between sensory axons and motoneurons after lesions of neonatal opossum CNS (Monodelphis domestica) in culture. 976 81

The purpose of this study was to observe functional recovery and motoneuron death after nerve transection-and-repair in neonatal versus young animals. One hundred nine Lewis rats underwent posterior tibial nerve transection-and-repair at 6 or 22 days of age. Fifty-two and fifty-seven nerves at the 6- and 22-day times were used for endpoint analysis at 1, 3, 10, and 14 months. These assessments included serial functional walking track analysis, electrophysiologic studies, muscle mass evaluation, motoneuron counts with retrograde horseradish peroxidase tracing, and histologic and morphometric nerve analysis. Walking track analysis and nerve conduction velocity indicated significantly poorer functional regeneration in the 6-day-old group than in the 22-day-old group. Muscle mass in the 6-day-old group did not recover as well as in the 22-day-old group. Motoneuron numbers stained with horseradish peroxidase were less in the 6-day-old group than in the 22-day-old group. In contrast, morphometric analysis did not reach significance. This study suggests that the same nerve injury sustained in a neonatal rat is less likely to demonstrate functional recovery than one sustained in a young rat.
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PMID:Long-term observation of the effect of peripheral nerve injury in neonatal and young rats. 981 Oct 5

The present study examined regeneration and restoration of function of the mammalian central vestibular system in the infant rat. The lateral vestibulospinal tract (LVST) of rats was completely transected unilaterally by a ventral approach. After a postoperative interval of one day to three months, the LVST was examined by anterograde transport of wheat-germ agglutinin-conjugated horseradish peroxidase (WGA-HRP) and retrograde transport of fluorescent dye. Twelve of the 22 LVST-transected rats showed successful regeneration. The regenerated fibers formed a compact fiber bundle, which sent terminals to their normal targets. The contribution of the regenerated fibers to functional recovery was estimated by analyzing the locomotor capacity of the transected rats. The locomotor movements were measured on the surface of a digitizer table by attaching a miniature resonance coil to the abdomen of the rats. Rats which shows normal locomotor movements represented a marked regeneration of LVST fibers. In contrast, rats with poorly-controlled locomotor movements showed unsuccessful regeneration. These results suggest that, contrary to previous thought, regeneration and functional restoration of the central vestibular system in young rats does occur.
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PMID:Axonal regeneration with functional restoration in the vestibulospinal tract in young rats. 985 22

Intraspinally implanting a nerve autograft (NAG) to promote axonal regeneration toward periphery was investigated as a surgical treatment for spinal cord injury in adult rats. Fifteen animals underwent a left hemisection of the spinal cord at T12 level and an intradural section of all ipsilateral lumbar ventral roots. In repaired animals (n = 9), the electrophysiologically selected left L3 and L4 lumbar ventral roots supplying the quadriceps muscle were anastomosed to a NAG. The NAG was taken from the right peroneal nerve and then ventrolaterally implanted into the cord at a level 7 mm rostral to the hemisection. In the control group (n = 6), sectioned lumbar ventral roots were left unrepaired. Nine months later, the animals were assessed with clinical, electrophysiological, and histological examinations. Muscle action potential and motor evoked potential were obtained from the denervated/reinnervated quadriceps in all repaired animals, with a mean amplitude of 918.3+/-328.9 microV and 215.8+/-39.7 microV, respectively. Horseradish peroxidase retrograde labeling from the denervated/repaired lumbar ventral roots, performed in five repaired animals, showed that the mean of labeled neurons, ipsilaterally located in the thoracic ventral horn near the implantation site, was 145.8+/-111.7. Histological analysis showed numerous myelinated axons in the NAG and denervated/repaired lumbar ventral roots of all repaired animals. The study of neuromuscular junctions furthermore confirmed numerous newly formed endplates appearing in the denervated/reinnervated quadriceps. These changes were absent in the control animals. These data indicate that the rostral thoracic spinal motoneurons can innervate the caudal denervated/repaired lumbar ventral roots and the target quadriceps via an implanted NAG, thereby inducing some functional recovery in adult rats after lower thoracic spinal cord injury.
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PMID:Reinnervation of denervated lumbar ventral roots and their target muscle by thoracic spinal motoneurons via an implanted nerve autograft in adult rats after spinal cord injury. 1036 17

The acellular nerve graft was utilised to restore a functional reinnervation of the biceps brachii muscle from the motoneuron pool of the cervical spinal cord. The musculocutaneous nerve stump was sutured to an acellular nerve graft, the opposite end of which was inserted into the cervical spinal cord cranial to the avulsed C5 ventral root. The acellular nerve graft was repopulated by Schwann cells heavily immunostained for NGFr within 90 days. The Schwann cells migrating from the nerve stump reached the spinal cord grey matter, where they stimulated the motoneurons to send axonal sprouts. The functional reinnervation of the biceps brachii muscle was assessed by means of the behavioural (grooming) test and EMG, the presence of myelinated and unmyelinated axons was demonstrated by light and electron microscopy. The axonal reconnection of the musculocutaneous nerve stump was verified by horseradish peroxidase retrograde labelling of the spinal motoneurons. Moreover, the motoneurons on the operated side of the C5 spinal segment displayed increased immunostaining for GAP-43 in comparison to the contralateral side, whereas the pattern of AChE histochemical reaction was similar on both the operated and contralateral side, of the C5 segment 150 days after acellular graft implantation. The regenerated axons bridged a 4-cm long originally acellular nerve graft to reach and reinnervate the biceps brachii muscle. The reinnervation of the neuromuscular junctions was morphologically determined by immunofluorescence for neurofilaments. The number of myelinated axons in the acellular nerve graft was significantly higher than those growing over the cellular graft, but their diameter was smaller. The results of experiments presented here demonstrate functional recovery of the biceps muscle reinnervation through the acellular nerve graft repopulated by migrating Schwann cells. The process of reinnervation by acellular nerve graft is however delayed and worse in comparison with the cellular graft.
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PMID:Acellular nerve graft re-seeded by Schwann cells migrating from the nerve stump can stimulate spinal motoneurons for functional reinnervation of the rat muscle. 1075 79

Intravenous administration of phenylephrine provokes a pattern of cellular activation in the nucleus of the solitary tract that resembles the central distributions of primary baroreceptor afferents supplied by the carotid sinus and aortic depressor nerves. Transganglionic transport and denervation methods were used in an experimental setting to test the dependence of phenylephrine-induced Fos immunoreactivity on the integrity of buffer nerve afferents, and to identify the subregions of the nucleus of the solitary tract supplied by each. Cholera toxin B-horseradish peroxidase injections into either or both nerves revealed terminal labeling concentrated in, but not restricted to, the dorsal commissural part of the nucleus of the solitary tract at the level of the apex of calamus scriptorius, and extending into the dorsal subnucleus at the level of the area postrema. Preferential ramifications of carotid sinus and aortic depressor nerve afferents at the levels of the commissural part of the nucleus and the area postrema, respectively, were reflected in the extent to which labeled fibers comingled with neurons exhibiting phenylephrine-induced Fos in dual labeling experiments. Complete sinoaortic denervation reduced by 90% the number of neurons exhibiting drug-induced Fos expression. Selective carotid and aortic sinus denervations effected partial reductions manifest preferentially in the caudal and rostral foci of the distribution, respectively. Reduced activational responses at the level of the area postrema of aortic sinus-denervated rats were accompanied by a reduction in cellular nicotinamide adenine dinucleotide phosphate-diaphorase activity in this region. Animals killed 30 days after complete sinoaortic denervation displayed no evidence of recovery of phenylephrine-induced Fos, while the strength and distribution of the response in rats that received selective carotid sinus denervation were indistinguishable from those seen in controls. These findings (i) support the dependence of phenylephrine-induced Fos expression on the integrity of carotid sinus and aortic depressor nerve afferents, (ii) provide anatomical and functional evidence that the two buffer nerves distribute differentially within the nucleus of the solitary tract, and (iii) implicate central reorganization as a likely basis for functional recovery of baroreflex mechanisms following partial sinoaortic denervation.
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PMID:Effects of selective sinoaortic denervations on phenylephrine-induced activational responses in the nucleus of the solitary tract. 1106 45

About 15% of retinal ganglion cells survive diffuse axonal injury of the optic nerve in adult rats. Following initial blindness, discrimination of visual stimuli in behavioral tests recovers within three weeks. To investigate the mechanisms promoting this functional recovery the axonal transport and the neurofilaments were studied. Intraocularly applied MiniRuby is transported until the place of crush and accumulated in enlarged axon terminals. Three weeks after lesion the anterograde transport of MiniRuby recovers distal to the place of crush. At the same point in time the retrograde transport of surviving retinal ganglion cells is restored which was visualized by horseradish peroxidase injected into the superior colliculus. The heavy neurofilament was stained immunohistochemically and analyzed statistically up to three weeks after optic nerve crush. The stained filaments in the axon fibers of retinal ganglion cells appear wavelike and/or fragmented up to day 8, but first signs of heavy neurofilament restitution in the fibers of the optic nerve are seen at day 12 after axonal injury. Because these results cannot be explained by longlasting axon regeneration, the present results provide convincing evidence for intrinsic axon repair soon after diffuse axonal injury that correlates in time with recovery of vision.
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PMID:Anatomical correlations of intrinsic axon repair after partial optic nerve crush in rats. 1193 90

Functional recovery was achieved in rats after repairing the transected left sixth and seventh cervical roots. Intercostal nerves were used for reanastomosis between the transected roots and the spinal cord, and acidic fibroblast growth factor with fibrin glue was applied. Experimental rats showed relevant functional recovery of gait and grooming reflexes. Electromyography demonstrated less denervation and more regeneration. Horseradish peroxidase retrograde axonal tracing disclosed a statistically significant increase of motor neuron survival, suggesting that motor neuron survival was significantly correlated with functional recovery. It is our belief that this novel treatment strategy may help patients with similar injuries in the future.
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PMID:Cervical root repair in adult rats after transection: recovery of forelimb motor function. 1268 24

Hypoglossal-facial nerve anastomosis (HFA) is the most popular surgical procedure to reinnervate facial muscles after injury of the facial nerve. Section of the hypoglossus causes paralysis and atrophy of the hemi-tongue. In the attempt to overcome this consequence, the hemihypoglossal-facial nerve anastomosis (HHFA) has been proposed and only a half of the main trunk of the hypoglossus is connected to the distal stump of the facial nerve. In the rat, we have studied experimentally the anatomical nuclear changes after HFA and HHFA with the aim of establishing the quantitative motoneuron innervation of facial muscles obtained with each one of the two operative options. Horseradish peroxidase (HRP) injected in both types of anastomosis labeled not only hypoglossal motoneurons, but also facial motoneurons. HFA appeared to offer a significant quantitative motoneuron innervation higher than HHFA and then a higher probable better functional recovery. Both HFA and HHFA performed immediately after section of the facial nerve in rats did not result in a phenomenon of motor hyperinnervation. In our experimental model, the proximal facial nerve stump was coagulated at the stylomastoid foramen to avoid regeneration. Then, the labeled motoneurons into the facial nucleus could really be the expression of axonal projections from facial motoneurons to the hypoglossus nerve and facial muscles. No labeled motoneurons were seen contralaterally as we observed previously after section and repair of several nerves.
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PMID:Motoneurons innervating facial muscles after hypoglossal and hemihypoglossal-facial nerve anastomosis in rats. 1519 65

Restoration of function after stroke may be associated with structural remodeling of neuronal connections outside the infarcted area. However, the spatiotemporal profile of poststroke alterations in neuroanatomical connectivity in relation to functional recovery is still largely unknown. We performed in vivo magnetic resonance imaging (MRI)-based neuronal tract tracing with manganese in combination with immunohistochemical detection of the neuronal tracer wheat-germ agglutinin horseradish peroxidase (WGA-HRP), to assess changes in intra- and interhemispheric sensorimotor network connections from 2 to 10 weeks after unilateral stroke in rats. In addition, functional recovery was measured by repetitive behavioral testing. Four days after tracer injection in perilesional sensorimotor cortex, manganese enhancement and WGA-HRP staining were decreased in subcortical areas of the ipsilateral sensorimotor network at 2 weeks after stroke, which was restored at later time points. At 4 to 10 weeks after stroke, we detected significantly increased manganese enhancement in the contralateral hemisphere. Behaviorally, sensorimotor functions were initially disturbed but subsequently recovered and plateaued 17 days after stroke. This study shows that manganese-enhanced MRI can provide unique in vivo information on the spatiotemporal pattern of neuroanatomical plasticity after stroke. Our data suggest that the plateau stage of functional recovery is associated with restoration of ipsilateral sensorimotor pathways and enhanced interhemispheric connectivity.
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PMID:Manganese-enhanced MRI of brain plasticity in relation to functional recovery after experimental stroke. 1798 47


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