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Autonomic Neuroscience : Basic &... Mar 2020Sexual dysfunction, following spinal cord injury (SCI), is highly dependent on the extent of injury. SCI disrupts the supraspinal innervation of the reproductive organs;...
Sexual dysfunction, following spinal cord injury (SCI), is highly dependent on the extent of injury. SCI disrupts the supraspinal innervation of the reproductive organs; resulting in structural and functional deficits. Relating the extent of SCI to these changes could eventually improve diagnoses and treatment planning of sexual dysfunction following SCI. In the present study, following chronic SCI of different severities (1/3 dorsal SCI (1/3 SCI), 2/3 dorsal SCI (2/3 SCI), and complete transection (Tx)) at T8 spinal level, histological changes of seminiferous tubules parameters in testis were examined. The diameter of seminiferous tubules (DST) and epithelial height of seminiferous tubules (HST) were significantly decreased in all SCI groups compared to control and sham. In addition, DST in 2/3 SCI and Tx groups and HST in Tx group were significantly decreased in comparison with 1/3 SCI animals. Nonetheless, the diameter of seminiferous tubules' lumen decreased significantly in 2/3 SCI and Tx compared to control, sham, and 1/3 SCI groups. Concerning cellular component, the number of spermatocytes and spermatids layers significantly decreased in both 1/3 and 2/3 SCI in comparison to normal. However, Tx had the most prominent deteriorating effect on these layers; indicating impairment in the process of spermatogenesis. These results show that the spinal tracts are part of the neural circuitries innervating the testis and responsible for their structural support. These tracts are mainly distributed between the lateral and ventral funiculi at T8 spinal level. Consequently, sparing ventral funiculi in the SCI prevents the severe decline in spermatogenesis.
Topics: Animals; Follicle Stimulating Hormone; Male; Organ Size; Rats, Sprague-Dawley; Spermatogenesis; Spinal Cord; Spinal Cord Injuries; Testis; Testosterone
PubMed: 31981803
DOI: 10.1016/j.autneu.2020.102639 -
Journal of Neurodevelopmental Disorders Dec 2019Down syndrome (DS), caused by the triplication of chromosome 21, results in a constellation of clinical features including changes in intellectual and motor function....
BACKGROUND
Down syndrome (DS), caused by the triplication of chromosome 21, results in a constellation of clinical features including changes in intellectual and motor function. Although altered neural development and function have been well described in people with DS, few studies have investigated the etiology underlying the observed motor phenotypes. Here, we examine the development, patterning, and organization of the spinal cord throughout life in the Ts65Dn mouse, a model that recapitulates many of the motor changes observed in people with DS.
METHODS
Spinal cords from embryonic to adult animals were processed for gene and protein expression (immunofluorescence) to track the spatiotemporal development of excitatory and inhibitory neurons and oligodendroglia. Postnatal analyses were focused on the lumbar region due to the reflex and gait abnormalities found in Ts65Dn mice and locomotive alterations seen in people with DS.
RESULTS
Between embryonic days E10.5 and E14.5, we found a larger motor neuron progenitor domain in Ts65Dn animals containing more OLIG2-expressing progenitor cells. These disturbed progenitors are delayed in motor neuron production but eventually generate a large number of ISL1+ migrating motor neurons. We found that higher numbers of PAX6+ and NKX2.2+ interneurons (INs) are also produced during this time frame. In the adult lumbar spinal cord, we found an increased level of Hb9 and a decreased level of Irx3 gene expression in trisomic animals. This was accompanied by an increase in Calretinin+ INs, but no changes in other neuronal populations. In aged Ts65Dn animals, both Calbindin+ and ChAT+ neurons were decreased compared to euploid controls. Additionally, in the dorsal corticospinal white matter tract, there were significantly fewer CC1+ mature OLs in 30- and 60-day old trisomic animals and this normalized to euploid levels at 10-11 months. In contrast, the mature OL population was increased in the lateral funiculus, an ascending white matter tract carrying sensory information. In 30-day old animals, we also found a decrease in the number of nodes of Ranvier in both tracts. This decrease normalized both in 60-day old and aged animals.
CONCLUSIONS
We show marked changes in both spinal white matter and neuronal composition that change regionally over the life span. In the embryonic Ts65Dn spinal cord, we observe alterations in motor neuron production and migration. In the adult spinal cord, we observe changes in oligodendrocyte maturation and motor neuron loss, the latter of which has also been observed in human spinal cord tissue samples. This work uncovers multiple cellular perturbations during Ts65Dn development and aging, many of which may underlie the motor deficits found in DS.
Topics: Animals; Disease Models, Animal; Down Syndrome; Female; Gene Expression Regulation, Developmental; Homeobox Protein Nkx-2.2; Homeodomain Proteins; Male; Mice, Transgenic; Neuroglia; Neurons; Nuclear Proteins; Spinal Cord; Transcription Factors; White Matter
PubMed: 31839007
DOI: 10.1186/s11689-019-9294-9 -
Molecular Neurobiology Feb 2020Neuroglial precursor cells (NPC) possess immune-modulatory properties by which they prevent immune-mediated injury in experimental autoimmune encephalomyelitis (EAE). It...
Neuroglial precursor cells (NPC) possess immune-modulatory properties by which they prevent immune-mediated injury in experimental autoimmune encephalomyelitis (EAE). It is unclear whether cell transplantation in a clinical-relevant setup induces ongoing therapeutic effects in a chronic-active model of progressive multiple sclerosis (MS). We examined whether human embryonic stem cell (hESC)-derived NPCs inhibit progressive EAE in Biozzi AB/H mice, manifesting with chronic-active neuroinflammation and demyelinated plaques. hESC-derived NPCs were propagated for 6-8 weeks as spheres enriched for Olig2+ cells to switch from neuronal to glial commitment and to enrich for oligodendrocyte progenitor cells. NPC were transplanted intracerebroventricularly at 30 days post-EAE induction, after the acute relapse. We evaluated effects of cell transplantation on clinical parameters, neuroinflammation, myelination, and axonal loss. Transplanted animals exhibited a significantly milder disease, reduced neuroinflammation, reduced demyelination, and reduced axonal loss as compared to control EAE mice. Toluidine-blue semi-thin staining showed a bystander neuroprotective effect of human precursor cells preventing the loss of myelinated fibers in superficial layer of the cervical dorsal funiculus. Human Olig2+ cells were detected along spinal cord meninges after 65 days of follow-up. In co-cultures in vitro, Olig2+ human precursors inhibited Concanavalin A-induced murine T cell activation and proliferation. To conclude, glial-committed human NPC induce ongoing immune-regulatory and neuroprotective effects, following transplantation into mice with a clinical-relevant model of chronic-active MS and during established disease, entering the chronic phase. These properties highlight the therapeutic potential of human NPC transplantation in chronic MS and their delivery via the cerebrospinal fluid.
Topics: Animals; Encephalomyelitis, Autoimmune, Experimental; Humans; Mice; Multiple Sclerosis; Myelin Sheath; Neural Stem Cells; Neurons; Oligodendrocyte Precursor Cells; Oligodendrocyte Transcription Factor 2; Stem Cell Transplantation
PubMed: 31656989
DOI: 10.1007/s12035-019-01802-7 -
Journal of Neurosurgery. Spine Oct 2019Dorsal spinal cord herniation is reportedly a rare condition. Here, the authors report an unusual case of dorsal spinal cord herniation at the thoracolumbar junction...
Dorsal spinal cord herniation is reportedly a rare condition. Here, the authors report an unusual case of dorsal spinal cord herniation at the thoracolumbar junction presenting with scalloping of ossification of the ligamentum flavum (OLF). A 75-year-old woman with a 2-year history of bilateral leg dysesthesia presented with progressive gait ataxia. Neurological examination showed bilateral patellar tendon hyperreflexia with loss of vibratory sensation and proprioception in her bilateral lower extremities. CT myelography revealed a posterior kink and dorsal herniation of the spinal cord at T11-12, with OLF between T10-11 and T12-L1. In addition, scalloping of the OLF was observed at T11-12 at the site of the herniated spinal cord. This scalloping was first noted 9 years previously and had been gradually progressing. The patient underwent surgical repair of the spinal cord herniation. Subsequently, her spinal cord herniation and vibratory sensation and proprioception in both legs partly improved, but gait ataxia remained unchanged. Dorsal spinal cord herniation reportedly occurs under conditions of vulnerability of the dorsal dura mater. In this case, acquired vulnerability of the dorsal dura mater owing to previous epidural catheter placement into the thoracolumbar space may have resulted in dorsal spinal cord herniation.
PubMed: 31628276
DOI: 10.3171/2019.8.SPINE19771 -
Brazilian Journal of Anesthesiology... 2019Intrathecal administration of non-steroidal anti-inflammatory drugs is more efficacious for post-operative pain management. Cyclooxygenase inhibiting non-steroidal...
BACKGROUND AND OBJECTIVES
Intrathecal administration of non-steroidal anti-inflammatory drugs is more efficacious for post-operative pain management. Cyclooxygenase inhibiting non-steroidal anti-inflammatory drugs like (S)-(+)-Ketoprofen, may be effective at lower intrathecal doses than parenteral ones. Preclinical safety regarding possible neurotoxicity associated with the intrathecal (S)-(+)-Ketoprofen was not evaluated. Here we analysed the neurotoxicity of intrathecally administered (S)-(+)-Ketoprofen in rats.
METHODS
A randomized placebo-controlled experimental study was conducted. Sprague-Dawley rats (250–300 g) aged 12–16 weeks were randomly divided into 2 treatments [100 and 800 μg (S)-(+)-Ketoprofen] and control (sterile water) groups. Intrathecal catheters were placed via the atlantoaxial space in anesthetized rats. Pinch-toe tests, motor function evaluations and histopathological examinations of the spinal cord and nerve roots were performed at days 3, 7 and 21. Spinal cord sections were evaluated by light microscopy for the dorsal axonal funiculus vacuolation, axonal myelin loss, neuronal chromatolysis, neuritis, meningeal inflammation, adhesions, and fibrosis.
RESULTS
Rats in all the groups exhibited normal pinch-toe testing response (score = 0) and normal gait at each observed time (motor function evaluation score = 1). Neurotoxicity was higher with treatments on days 3 and 7 than that on day 21 (2, 3, 0, = 0.044; 2, 5, 0, = 0.029, respectively). On day 7, the total scores reflecting neuronal damage were higher in the 800 μg group than those in the 100 μg and Control Groups (5, 3, 0, = 0.048, respectively).
CONCLUSION
Intrathecal (S)-(+)-Ketoprofen caused dose-dependent neurohistopathological changes in rats on days 3 and 7 after injection, suggesting that (S)-(+)-Ketoprofen should not be intrathecally administered.
Topics: Animals; Anti-Inflammatory Agents, Non-Steroidal; Dose-Response Relationship, Drug; Injections, Spinal; Ketoprofen; Male; Neurotoxicity Syndromes; Rats; Rats, Sprague-Dawley; Spinal Cord; Time Factors
PubMed: 31371174
DOI: 10.1016/j.bjan.2019.03.006 -
Brain Research May 2019The corticospinal tract (CST) has a complex and long trajectory that originates in the cerebral cortex and ends in the spinal cord. Semaphorin 6A (Sema6A), a member of...
The corticospinal tract (CST) has a complex and long trajectory that originates in the cerebral cortex and ends in the spinal cord. Semaphorin 6A (Sema6A), a member of the semaphorin family, is an important regulator of CST axon guidance. Previous studies have shown that postnatal Sema6A mutant mice have CST defects at the midbrain-hindbrain boundary and medulla. However, the routes the aberrant fibers take throughout the Sema6A mutant brain remain unknown. In this study, we performed 3D reconstruction of immunostained CST fibers to reevaluate the details of the abnormal CST trajectories in the brains of adult Sema6A mutant mice. Our results showed that the axon guidance defects reported in early postnatal mutants were consistently observed in adulthood. Those abnormal trajectories revealed by 3D analysis of brain sections were, however, more complex and variable than previously thought. In addition, 3D analysis allowed us to identify a few new patterns of aberrant projections. First, a subset of fibers that separated from and descended in parallel to the main bundle projected laterally at the caudal pons, subsequently changed direction by turning caudally, and extended to the medulla. Second, some abnormal fibers returned to the correct trajectory after deviating substantially from the original tract. Third, some fibers reached the pyramidal decussation normally but did not enter the dorsal funiculus. Section immunostaining combined with 3D reconstruction is a powerful method to track long projection fibers and to examine the entire nerve tracts of both normal and abnormal animals.
Topics: Animals; Brain; Mice, Knockout; Neuroanatomical Tract-Tracing Techniques; Pyramidal Tracts; Semaphorins
PubMed: 30599138
DOI: 10.1016/j.brainres.2018.12.041 -
Journal of Neuroscience Methods Jan 2019Background Nonhuman primates (NHP) may provide the most adequate (in terms of neuroanatomy and neurophysiology) model of spinal cord injury (SCI) for testing...
Background Nonhuman primates (NHP) may provide the most adequate (in terms of neuroanatomy and neurophysiology) model of spinal cord injury (SCI) for testing regenerative therapies, but bioethical considerations exclude their use in severe SCI. New Method A reproducible model of SCI at the lower thoracic level has been developed in Rhesus macaques. The model comprises surgical resection of 25% of the spinal cord in the projection of the dorsal funiculus and dorsolateral corticospinal pathways, controlled via registration of intraoperative evoked potentials (EPs). The animals were evaluated using the modified Hindlimb score, MRI, SSEP, and MEP over a time period of 8-12 weeks post-SCI, followed by histological examination. Results Complete disappearance of intraoperative EPs from distal hindlimb muscles without restoration within two weeks post-SCI was an indicator for irreversible disruption of the abovementioned pathways. As a result, controlled damage to the spinal cord was achieved in three NHPs, clinically manifested as irreversible lower monoplegia. No significant functional restoration was observed in these NHPs up to 12 weeks post-SCI. Demyelination of the damaged ascending tracts was detected. Disturbances in pelvic organ function were not observed in all animals. Comparison with existing methods The new method of EPs-guided SCI allows a more controlled and irreversible damage to the spinal cord compared with contusion and other transection approaches. Conclusions This method to induce complete SCI in NHP is well tolerated, reproducible and ethically acceptable: these are valuable attributes in a preclinical model that will hopefully help advance testing of new regenerative therapies in SCI.
Topics: Animals; Disease Models, Animal; Evoked Potentials, Motor; Evoked Potentials, Somatosensory; Intraoperative Neurophysiological Monitoring; Macaca mulatta; Male; Neurosurgical Procedures; Spinal Cord Injuries
PubMed: 30393204
DOI: 10.1016/j.jneumeth.2018.10.030 -
Acta Neurochirurgica Dec 2018Spinal cord stimulation (SCS) is an established treatment option for patients with refractory chronic pain conditions. While effects of SCS on dorsal horn neuronal...
BACKGROUND
Spinal cord stimulation (SCS) is an established treatment option for patients with refractory chronic pain conditions. While effects of SCS on dorsal horn neuronal circuitries are intensively studied, current knowledge on the impact of SCS on descending pain pathways is scarce and relies on preclinical data. We aimed to address this topic and hypothesized a significant effect of SCS on descending pain modulation. In light of current efforts to determine the sensitivity of "static" versus "dynamic" somatosensory parameters to characterize pathophysiological pain conditions, all SCS patients were carefully investigated using both classes of somatosensory outcome parameters.
METHODS
Descending pain pathways were investigated by using a "Cold Pressor Test." This test enables to evaluate the efficacy of conditioned pain modulation (CPM) at the individual level. CPM efficacy was assessed in eight neuropathic pain patients (age 55.5 ± 10.6) during the two conditions stimulator "ON" and "OFF." The impact of SCS on "static" and "dynamic" somatosensory parameters was explored by using a quantitative sensory testing (QST) battery.
RESULTS
CPM efficacy on pressure pain sensitivity was nearly absent during "OFF" (- 1.2 ± 5.6% facilitation), but increased significantly to 16.3 ± 3.4% inhibition during "ON" (p = 0.03). While most "static" nociceptive QST parameters, represented by mechanical/thermal pain thresholds, exhibited only small effects of SCS (p > 0.05), the wind-up ratio was strongly reduced to within the normal range during "ON" (p = 0.04; Cohen's d = 1.0). Dynamic mechanical allodynia was abolished in six of seven patients.
CONCLUSIONS
Our study provides first human evidence for an impact of SCS on descending pain pathways in the dorsolateral funiculus and emphasizes the significance of "dynamic" pain measures like "CPM"-efficacy and "temporal summation" to evaluate SCS treatment effects. Future prospective studies may use these measures of nociceptive processing to predict SCS therapy response.
Topics: Adult; Female; Humans; Male; Middle Aged; Neural Inhibition; Neuralgia; Pain Threshold; Postsynaptic Potential Summation; Spinal Cord; Spinal Cord Stimulation
PubMed: 30293158
DOI: 10.1007/s00701-018-3669-7 -
Developmental Neurobiology Nov 2018Numerous tissue transplantations have demonstrated that otocysts can develop into normal ears in any location in all vertebrates tested thus far, though the pattern of...
Numerous tissue transplantations have demonstrated that otocysts can develop into normal ears in any location in all vertebrates tested thus far, though the pattern of innervation of these transplanted ears has largely been understudied. Here, expanding on previous findings that transplanted ears demonstrate capability of local brainstem innervation and can also be innervated themselves by efferents, we show that inner ear afferents grow toward the spinal cord mostly along existing afferent and efferent fibers and preferentially enter the dorsal spinal cord. Once in the dorsal funiculus of the spinal cord, they can grow toward the hindbrain and can diverge into vestibular nuclei. Inner ear afferents can also project along lateral line afferents. Likewise, lateral line afferents can navigate along inner ear afferents to reach hair cells in the ear. In addition, transplanted ears near the heart show growth of inner ear afferents along epibranchial placode-derived vagus afferents. Our data indicate that inner ear afferents can navigate in foreign locations, likely devoid of any local ear-specific guidance cues, along existing nerves, possibly using the nerve-associated Schwann cells as substrate to grow along. However, within the spinal cord and hindbrain, inner ear afferents can navigate to vestibular targets, likely using gradients of diffusible factors that define the dorso-ventral axis to guide them. Finally, afferents of transplanted ears functionally connect to native hindbrain vestibular circuitry, indicated by eliciting a startle behavior response, and providing excitatory input to specific sets of extraocular motoneurons.
Topics: Afferent Pathways; Animals; Brain Stem; Ear, Inner; Hair Cells, Auditory; Motor Neurons; Neurons, Afferent; Rhombencephalon; Schwann Cells; Spinal Cord
PubMed: 30027559
DOI: 10.1002/dneu.22629 -
The European Journal of Neuroscience Nov 2017The dorsal spinal cord, which is essential for somatosensory transmission, comprises a heterogeneous population of neurons with distinct axonal lengths and projection...
The dorsal spinal cord, which is essential for somatosensory transmission, comprises a heterogeneous population of neurons with distinct axonal lengths and projection patterns. Although the developmental origin of local-circuit interneurons in the dorsal spinal cord has been well characterized, that of long-range neurons extending axons over a long distance such as supraspinal projection neurons and propriospinal neurons is largely unknown. In this study, we performed birthdate and lineage analyses of these long-range neurons in the mouse dorsal spinal cord. Unilateral injection of a retrograde neuronal tracer, cholera toxin B, into the brain or spinal cord efficiently labeled supraspinal projection neurons localized in Rexed's lamina I and the dorsolateral funiculus (DLF) and long-range propriospinal neurons localized in the DLF, all of which had ipsi- and contralaterally projecting populations. Most of these neurons were born between E9.5 and E10.5, much earlier than in the case of the neurogenesis of local-circuit neurons. Lineage analysis using an Lbx1-Cre mouse line demonstrated that most long-range neurons were derived from Lbx1-positive neuronal progenitors, except in the case of the contralaterally projecting propriospinal neurons. Characterization of their neurotransmitter identity revealed that almost all of the supraspinal projection neurons were excitatory, whereas the long-range propriospinal neurons comprised both excitatory and inhibitory populations. These results suggest that the supraspinal projection neurons were derived from the early-born dI5 progenitor domain and that the long-range propriospinal ones arose from several early-born progenitor domains.
Topics: Animals; Axons; Female; Mice, Inbred C57BL; Mice, Inbred ICR; Neural Pathways; Neural Stem Cells; Neuroanatomical Tract-Tracing Techniques; Neurons; Spinal Cord
PubMed: 28977701
DOI: 10.1111/ejn.13736