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Cell Transplantation 2013Amyotrophic lateral sclerosis (ALS) is a fatal disease that involves the degeneration of cortical and spinal motor neurons. Mutant SOD1(G93A) rats constitute a good...
Amyotrophic lateral sclerosis (ALS) is a fatal disease that involves the degeneration of cortical and spinal motor neurons. Mutant SOD1(G93A) rats constitute a good animal model for this pathological condition. We have previously demonstrated that transplantation of neonatal olfactory ensheathing cells (OECs) into the dorsal funiculus of the spinal cord of mutant SOD1(G93A) transgenic rats increases the survival of spinal motor neurons and remyelinates the impaired axons through the pyramidal tract. In the present study, we examine whether intracranial cell implantation could also exert a similar effect on cortical motor neurons and on the lower motor neurons in the spinal cord. We injected OECs from the bulb of 7-day-old GFP green rats into the corona radiata of adult SOD1 mutant rats stereotaxically to observe any changes of the upper motor neurons as well as the lower motor neurons. We found that more motor neurons at both the motor cortices and ventral horns of the spinal cord survived in grafted ALS rats than in control rats. Prolonged survival and behavioral tests including a screen test, hind limb extension, rotarod, and gait control showed that the treated animals were better than the control group. This manuscript is published as part of the International Association of Neurorestoratology (IANR) supplement issue of Cell Transplantation.
Topics: Amyotrophic Lateral Sclerosis; Animals; Disease Models, Animal; Immunohistochemistry; Male; Motor Neurons; Olfactory Bulb; Rats; Rats, Sprague-Dawley; Superoxide Dismutase; Superoxide Dismutase-1
PubMed: 23993044
DOI: 10.3727/096368913X672208 -
Journal of Neurophysiology Oct 2013Transmission through descending pathways to lumbar motoneurons, although important for voluntary walking in humans and rats, has not been fully understood at the...
Transmission through descending pathways to lumbar motoneurons, although important for voluntary walking in humans and rats, has not been fully understood at the cellular level in contusion models. Major descending pathways innervating lumbar motoneurons include those at corticospinal tract (CST) and ventrolateral funiculus (VLF). We examined transmission and plasticity at synaptic pathways from dorsal (d)CST and VLF to individual motoneurons located in ventral horn and interneurons located in dorsomedial gray matter at lumbar segments after thoracic chronic contusion in adult anesthetized rats. To accomplish this, we used intracellular electrophysiological recordings and performed acute focal spinal lesions during the recordings. We directly demonstrate that after thoracic T10 chronic contusion the disrupted dCST axons spontaneously form new synaptic contacts with individual motoneurons, extending around the contusion cavity, through spared ventrolateral white matter. These detour synaptic connections are very weak, and strengthening these connections in order to improve function may be a target for therapeutic interventions after spinal cord injury (SCI). We found that degradation of scar-related chondroitin sulfate proteoglycans with the enzyme chondroitinase ABC (ChABC) combined with adeno-associated viral (AAV) vector-mediated prolonged delivery of neurotrophin NT-3 (AAV-NT3) strengthened these spontaneously formed connections in contused spinal cord. Moreover, ChABC/AAV-NT3 treatment induced the appearance of additional detour synaptic pathways innervating dorsomedial interneurons. Improved transmission in ChABC/AAV-NT3-treated animals was associated with increased immunoreactivity of 5-HT-positive fibers in lumbar dorsal and ventral horns. Improved locomotor function assessed with automated CatWalk highlights the physiological significance of these novel connections.
Topics: Animals; Chondroitin ABC Lyase; Contusions; Dependovirus; Female; Genetic Therapy; Interneurons; Locomotion; Motor Neurons; Neuronal Plasticity; Neurotrophin 3; Pyramidal Tracts; Rats; Rats, Sprague-Dawley; Spinal Cord Injuries; Synapses; Thoracic Injuries
PubMed: 23864374
DOI: 10.1152/jn.00427.2013 -
Scientific Reports 2013Spinal cord injury (SCI) is a severe condition leading to enduring motor deficits. When lesions are incomplete, promoting spinal cord plasticity might be a useful...
Spinal cord injury (SCI) is a severe condition leading to enduring motor deficits. When lesions are incomplete, promoting spinal cord plasticity might be a useful strategy to elicit functional recovery. Here we investigated whether long-term fluoxetine administration in the drinking water, a treatment recently demonstrated to optimize brain plasticity in several pathological conditions, promotes motor recovery in rats that received a C4 dorsal funiculus crush. We show that fluoxetine administration markedly improved motor functions compared to controls in several behavioral paradigms. The improved functional effects correlated positively with significant sprouting of intact corticospinal fibers and a modulation of the excitation/inhibition balance. Our results suggest a potential application of fluoxetine treatment as a non invasive therapeutic strategy for SCI-associated neuropathologies.
Topics: Animals; Disease Models, Animal; Fluoxetine; Gait; Male; Motor Activity; Motor Cortex; Neuronal Plasticity; Psychomotor Performance; Rats; Recovery of Function; Selective Serotonin Reuptake Inhibitors; Spinal Cord; Spinal Cord Injuries; Time Factors
PubMed: 23860568
DOI: 10.1038/srep02217 -
Stem Cell Research Sep 2013The loss of oligodendroglia and demyelination contributes to the lack of functional recovery after spinal cord injury. The transplantation of adult neural progenitor...
Bone morphogenetic proteins prevent bone marrow stromal cell-mediated oligodendroglial differentiation of transplanted adult neural progenitor cells in the injured spinal cord.
The loss of oligodendroglia and demyelination contributes to the lack of functional recovery after spinal cord injury. The transplantation of adult neural progenitor cells (NPCs) might be a promising strategy to replace oligodendroglia lost after injury, however only a very small proportion of grafted NPCs differentiate into oligodendroglia. The present study aimed to investigate whether co-transplantation of subventricular zone-derived NPCs with bone marrow stromal cells (BMSCs) will enhance oligodendroglial differentiation of NPCs. In vitro, oligodendroglial differentiation was strongly enhanced by co-cultivation of NPCs with BMSCs or BMSC-conditioned medium. For in vivo experiments, adult Fischer 344 rats underwent cervical dorsal funiculus transections, immediately followed by grafting of 5-bromo-2'-deoxyuridine (BrdU) pre-labeled syngeneic NPCs mixed with BMSCs isolated from adult bone marrow. Six weeks post-injury and grafting, BMSC-containing grafts filled the lesion cavity but did not enhance oligodendroglial differentiation of co-grafted NPCs. The failure of BMSCs to induce oligodendroglial differentiation in vivo coincided with a rapid upregulation of bone morphogenetic protein 2/4 (BMP2/4) around the injury site and in vitro data demonstrated that BMP2/4 can override the oligodendrogenic effects of BMSCs. Moreover, blocking BMP activity can rescue the effect of BMSCs on NPCs. Thus, neutralization of BMP or BMP signaling might be required to allow for BMSC-induced oligodendroglial differentiation of grafted NPCs in the injured spinal cord.
Topics: Animals; Bone Marrow Transplantation; Bone Morphogenetic Protein 2; Bone Morphogenetic Protein 4; Cell Differentiation; Female; Humans; Immunohistochemistry; Mesenchymal Stem Cell Transplantation; Mesenchymal Stem Cells; Neural Stem Cells; Oligodendroglia; Rats; Rats, Inbred F344; Rats, Sprague-Dawley; Rats, Transgenic; Spinal Cord Injuries
PubMed: 23770801
DOI: 10.1016/j.scr.2013.05.003 -
Experimental Neurology Oct 2013In conscious rats, intramuscular injection of 2.5% formalin into the gastrocnemius muscle, at volumes between 25 and 200 μl, evoked dose-dependent biphasic persistent...
In conscious rats, intramuscular injection of 2.5% formalin into the gastrocnemius muscle, at volumes between 25 and 200 μl, evoked dose-dependent biphasic persistent flinching activities: phase 1 (0-10 min) and phase 2 (10-60 min). During this intramuscular formalin-induced ipsilateral muscle nociception, bilateral secondary mechanical hyperalgesia and heat hypoalgesia assessed by measuring thresholds of paw withdrawal reflex to noxious mechanical and heat stimuli were observed (P<0.05). Lesion of either the ipsilateral dorsal funiculus (DF) or contralateral thalamic mediodorsal (MD) nucleus significantly alleviated the formalin-induced flinches in both phase 1 and phase 2 of the behavioral response, and blocked the occurrence of secondary mechanical hyperalgesia, but not heat hypoalgesia. By contrast, lesion of the ipsilateral dorsal lateral funiculus (DLF) or contralateral thalamic ventromedial (VM) nucleus markedly enhanced the formalin induced flinching behavior in the late part (30-60 min) of phase 2 alone; phase 1 and early part (10-30 min) of phase 2 response were unaffected. Heat hypoalgesia, but not mechanical hyperalgesia, was markedly attenuated by this treatment (P<0.05). Microinjection of GABA (0.1 μg/0.5 μl) into the thalamic MD nucleus significantly depressed the intramuscular formalin-induced biphasic persistent nociception, and the occurrence of bilateral secondary mechanical hyperalgesia was significantly delayed (P<0.05). By contrast, microinjection of GABA into the thalamic VM nucleus significantly enhanced the formalin-induced nociceptive behavior in the late part (30-60 min) of phase 2, and the bilateral secondary heat hypoalgesia was temporarily prevented (P<0.05). The present study demonstrates that intramuscular formalin evokes biphasic muscle nociception, and that bilateral secondary mechanical hyperalgesia and heat hypoalgesia are differentially controlled by endogenous descending facilitation and inhibition respectively. It is further suggested that thalamic MD nucleus and VM nucleus constitute an endogenous discriminative, modulatory system that exerts, via pathways in the DF and DLF, descending facilitatory and inhibitory actions on responses to peripheral afferent activity evoked by noxious mechanical and heat stimulation.
Topics: Animals; Formaldehyde; Hyperalgesia; Injections, Intramuscular; Male; Motor Activity; Muscle, Skeletal; Nociception; Pain Measurement; Physical Stimulation; Pyramidal Tracts; Rats; Rats, Sprague-Dawley; Reflex; Spinal Cord; Spinothalamic Tracts; Thalamic Nuclei
PubMed: 23756144
DOI: 10.1016/j.expneurol.2013.06.001 -
The Journal of Pain Aug 2013Neuropathic pain is frequently characterized by spontaneous pain (ie, pain at rest) and, in some cases, by cold- and touch-induced allodynia. Mechanisms underlying the...
UNLABELLED
Neuropathic pain is frequently characterized by spontaneous pain (ie, pain at rest) and, in some cases, by cold- and touch-induced allodynia. Mechanisms underlying the chronicity of neuropathic pain are not well understood. Rats received spinal nerve ligation (SNL) and were monitored for tactile and thermal thresholds. While heat hypersensitivity returned to baseline levels within approximately 35 to 40 days, tactile hypersensitivity was still present at 580 days after SNL. Tactile hypersensitivity at post-SNL day 60 (D60) was reversed by microinjection of 1) lidocaine; 2) a cholecystokinin 2 receptor antagonist into the rostral ventromedial medulla; or 3) dorsolateral funiculus lesion. Rostral ventromedial medulla lidocaine at D60 or spinal ondansetron, a 5-hydroxytryptamine 3 antagonist, at post-SNL D42 produced conditioned place preference selectively in SNL-treated rats, suggesting long-lasting spontaneous pain. Touch-induced FOS was increased in the spinal dorsal horn of SNL rats at D60 and prevented by prior dorsolateral funiculus lesion, suggesting that long-lasting tactile hypersensitivity depends upon spinal sensitization, which is mediated in part by descending facilitation, in spite of resolution of heat hypersensitivity.
PERSPECTIVE
These data suggest that spontaneous pain is present for an extended period of time and, consistent with likely actions of clinically effective drugs, is maintained by descending facilitation.
Topics: Afferent Pathways; Anesthetics, Local; Animals; Benzodiazepines; Conditioning, Operant; Disease Models, Animal; Hormone Antagonists; Hyperalgesia; Lidocaine; Male; Medulla Oblongata; Neuralgia; Oncogene Proteins v-fos; Ondansetron; Pain Measurement; Pain Threshold; Rats; Rats, Sprague-Dawley; Serotonin Antagonists; Spinal Nerves; Time Factors
PubMed: 23602267
DOI: 10.1016/j.jpain.2013.02.011 -
Toxicological Sciences : An Official... Jul 2013To investigate the neurotoxicity profile of glycidol and its effect on developmental hippocampal neurogenesis, pregnant Sprague Dawley rats were given drinking water...
To investigate the neurotoxicity profile of glycidol and its effect on developmental hippocampal neurogenesis, pregnant Sprague Dawley rats were given drinking water containing 0, 100, 300, or 1000 ppm glycidol from gestational day 6 until weaning on day 21 after delivery. At 1000 ppm, dams showed progressively worsening gait abnormalities, and histopathological examination showed generation of neurofilament-L(+) spheroids in the cerebellar granule layer and dorsal funiculus of the medulla oblongata, central chromatolysis in the trigeminal nerve ganglion cells, and axonal degeneration in the sciatic nerves. Decreased dihydropyrimidinase-like 3(+) immature granule cells in the subgranular zone (SGZ) and increased immature reelin(+) or calbindin-2(+) γ-aminobutyric acid-ergic interneurons and neuron-specific nuclear protein (NeuN)(+) mature neurons were found in the dentate hilus of the offspring of the 1000 ppm group on weaning. Hilar changes remained until postnatal day 77, with the increases in reelin(+) and NeuN(+) cells being present at ≥ 300 ppm, although the SGZ change disappeared. Thus, glycidol caused axon injury in the central and peripheral nervous systems of adult rats, suggesting that glycidol targets the newly generating nerve terminals of immature granule cells, resulting in the suppression of late-stage hippocampal neurogenesis. The sustained hilar changes may be a sign of continued aberrations in neurogenesis and migration. The no-observed-adverse-effect level was determined to be 300 ppm (48.8mg/kg body weight/day) for dams and 100 ppm (18.5mg/kg body weight/day) for offspring. The sustained developmental exposure effect on offspring neurogenesis was more sensitive than the adult axonal injury.
Topics: Aging; Animals; Apoptosis; Axons; Cell Differentiation; Dose-Response Relationship, Drug; Epoxy Compounds; Female; Hippocampus; Male; Neurogenesis; Neurons; Pregnancy; Prenatal Exposure Delayed Effects; Propanols; Rats; Rats, Sprague-Dawley; Reelin Protein
PubMed: 23596259
DOI: 10.1093/toxsci/kft092 -
Journal of Neurotrauma Jun 2013Blocking the action of inhibitory molecules at sites of central nervous system injury has been proposed as a strategy to promote axonal regeneration and functional...
Blocking the action of inhibitory molecules at sites of central nervous system injury has been proposed as a strategy to promote axonal regeneration and functional recovery. We have previously shown that genetic deletion or competitive antagonism of EphA4 receptor activity promotes axonal regeneration and functional recovery in a mouse model of lateral hemisection spinal cord injury. Here we have assessed the effect of blocking EphA4 activation using the competitive antagonist EphA4-Fc in a rat model of thoracic contusive spinal cord injury. Using a ledged tapered balance beam and open-field testing, we observed significant improvements in recovery of locomotor function after EphA4-Fc treatment. Consistent with functional improvement, using high-resolution ex vivo magnetic resonance imaging at 16.4T, we found that rats treated with EphA4-Fc had a significantly increased cross-sectional area of the dorsal funiculus caudal to the injury epicenter compared with controls. Our findings indicate that EphA4-Fc promotes functional recovery following contusive spinal cord injury and provides further support for the therapeutic benefit of treatment with the competitive antagonist in acute cases of spinal cord injury.
Topics: Animals; Blotting, Western; Brain; Disease Models, Animal; Enzyme-Linked Immunosorbent Assay; Female; Humans; Immunoglobulin Fc Fragments; Magnetic Resonance Imaging; Rats; Rats, Wistar; Receptor, EphA4; Recombinant Fusion Proteins; Recovery of Function; Spinal Cord Injuries; Transfection
PubMed: 23557244
DOI: 10.1089/neu.2012.2729 -
Autonomic Neuroscience : Basic &... Jun 2013Cardiovascular dysfunction usually occurs after high thoracic and cervical spinal cord injury (SCI). The disruption of supraspinal vasomotor pathways (SVPs) results in...
Cardiovascular dysfunction usually occurs after high thoracic and cervical spinal cord injury (SCI). The disruption of supraspinal vasomotor pathways (SVPs) results in the loss of bulbospinal regulation of sympathetic preganglionic neurons, leading to hypotension and compensatory tachycardia at rest. Episodic autonomic dysreflexia can develop upon sensory stimulation below the level of injury. In rodents, the precise spatial distribution of SVPs in the spinal cord originating from the rostral ventrolateral medulla (RVLM) has not been fully defined. To facilitate future studies of axon regeneration to regain cardiovascular control, we injected biotinylated dextran amine (BDA) bilaterally into the RVLM to anterogradely trace SVPs in Fischer 344 (F344) rats. Three weeks later, BDA-labeled descending projections were predominantly localized within the dorsolateral funiculus throughout the cervical and thoracic spinal segments as expected. Additionally, BDA-labeled fibers were also observed in ventral white matter. After a T4 dorsal hemisection to interrupt the dorsolateral funiculus, BDA labeled terminals originating from the ventral white matter as well as serotonergic projections were still detected in regions of autonomic nuclei below the injury. Based on these results, we examined cardiovascular responses after different lesions at spinal level T4, including lateral or dorsal hemisection, dorsolateral or complete transection. Hemodynamic dysfunction and autonomic dysreflexia were only elicited in rats with complete T4 transections when all SVPs were disrupted. Hence, F344 rats with complete T4 transections provide a reliable model for investigating means to improve cardiovascular functional recovery after SCI.
Topics: Animals; Autonomic Dysreflexia; Blood Pressure; Female; Heart Rate; Neural Pathways; Rats; Rats, Inbred F344; Spinal Cord Injuries; Vasomotor System
PubMed: 23466042
DOI: 10.1016/j.autneu.2013.02.001 -
The European Journal of Neuroscience May 2013The current study examined the role of the lateral reticular nucleus (LRN) in modulating the cardiosomatic reflex (CSR) induced by intrapericardial capsaicin in the...
The current study examined the role of the lateral reticular nucleus (LRN) in modulating the cardiosomatic reflex (CSR) induced by intrapericardial capsaicin in the anesthetized rat. Intrapericardial capsaicin was administered, and the CSR was monitored via electromyogram responses of the dorsal spinotrapezius muscle. Electrical stimulation of the LRN (10, 20 and 30 μA) depressed the CSR induced by intrapericardial capsaicin in an intensity-dependent manner. Microinjection of glutamate (4, 10, 20 and 40 nmol, in 0.2 μL) into the LRN replicated the effects of electrical stimulation. Furthermore, bilateral transections of the dorsolateral funiculus (DLF) decreased the LRN electrical stimulation-induced inhibition of the electromyogram responses. Intrathecal administration of the α2 -adrenergic receptor antagonist yohimbine or the serotonergic receptor antagonist methysergide significantly attenuated the LRN electrical stimulation-induced inhibition of the electromyogram responses. However, intrathecal application of the opioid receptor antagonist naloxone had no effect on the LRN electrical stimulation-induced inhibition. These results suggest that the LRN-DLF-spinal cord pathway is involved in descending inhibition of the CSR, and spinal α2 -adrenergic and serotonergic receptors participate in this descending inhibition.
Topics: Animals; Capsaicin; Electric Stimulation; Electromyography; Glutamic Acid; Heart; Male; Medulla Oblongata; Muscle Contraction; Muscle, Skeletal; Naloxone; Neural Pathways; Rats; Rats, Sprague-Dawley; Reflex; Sensory System Agents
PubMed: 23465085
DOI: 10.1111/ejn.12170