Journal of neurotrauma
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Journal of neurotrauma · Jun 2011
Comparative StudyDifferential effects of low versus high amounts of weight supported treadmill training in spinally transected rats.
Intensive weight-supported treadmill training (WSTT) improves locomotor function following spinal cord injury. Because of a number of factors, undergoing intensive sessions of training may not be feasible. Whether reduced amounts of training are sufficient to enhance spinal plasticity to a level that is necessary for improving function is not known. ⋯ Synaptophysin expression, but not BDNF or TrkB expression was correlated with the recovery of stepping function. These findings suggested that a large amount of weight-supported treadmill training was necessary for restoring synaptic connections to motor neurons within the locomotor generating circuitry. Although a large amount of training was best for recovery, small amounts of training were associated with incremental gains in function and increased BDNF levels.
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Journal of neurotrauma · Jun 2011
Sustained survival and maturation of adult neural stem/progenitor cells after transplantation into the injured brain.
Multipotent neural stem/progenitor cells (NS/NPCs) that are capable of generating neurons and glia offer enormous potential for treating neurological diseases. Adult NS/NPCs that reside in the mature mammalian brain can be isolated and expanded in vitro, and could be a potential source for autologous transplantation to replace cells lost to brain injury or disease. When these cells are transplanted into the normal brain, they can survive and become region-specific cells. ⋯ Many cells migrated out of the injection site into surrounding areas expressing astrocyte or oligodendrocyte markers. Whole cell patch-clamp recording at 4 weeks showed that transplanted cells possessed typical mature glial cell properties. These data demonstrate that adult NS/NPCs can survive in an injured heterotypic environment for an extended period and become functional cells.
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Journal of neurotrauma · Jun 2011
A selective phosphodiesterase-4 inhibitor reduces leukocyte infiltration, oxidative processes, and tissue damage after spinal cord injury.
We tested the hypothesis that a selective phosphodiesterase type 4 inhibitor (PDE4-I; IC486051) would attenuate early inflammatory and oxidative processes following spinal cord injury (SCI) when delivered during the first 3 days after injury. Rats receiving a moderately severe thoracic-clip-compression SCI were treated with the PDE4-I (0.5, 1.0, and 3.0 mg/kg IV) in bolus doses from 2-60 h post-injury. Doses at 0.5 mg/kg and 1.0 mg/kg significantly decreased myeloperoxidase (MPO) enzymatic activity (neutrophils), expression of a neutrophil-associated protein and of ED-1 (macrophages), and estimates of lipid peroxidation in cord lesion homogenates at 24 h and 72 h post-injury by 25-40%. ⋯ The PDE4-I treatment also increased white matter volume near the lesion at 8 weeks after SCI. In conclusion, the PDE4-I reduced key markers of oxidative stress and leukocyte infiltration, producing cellular protection, locomotor improvements, and a reduction in neuropathic pain. Early inhibition of PDE4 is neuroprotective after SCI when given acutely and briefly at sufficient doses.
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Journal of neurotrauma · Jun 2011
Blast exposure in rats with body shielding is characterized primarily by diffuse axonal injury.
Blast-induced traumatic brain injury (TBI) is the signature insult in combat casualty care. Survival with neurological damage from otherwise lethal blast exposures has become possible with body armor use. We characterized the neuropathologic alterations produced by a single blast exposure in rats using a helium-driven shock tube to generate a nominal exposure of 35 pounds per square inch (PSI) (positive phase duration ∼ 4 msec). ⋯ Increased blood-brain barrier permeability (as measured by IgG staining) was seen at 24 h and primarily affected the contralateral cortex. Axonal injury was the most prominent feature during the initial 2 weeks following blast exposure, although degeneration of other neuronal processes was also present. Strikingly, silver staining revealed otherwise undetected abnormalities, and therefore represents a recommended outcome measure in future studies of blast TBI.
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Journal of neurotrauma · Jun 2011
Reactive astrocytes inhibit the survival and differentiation of oligodendrocyte precursor cells by secreted TNF-α.
Axonal demyelination is a consistent pathological characteristic of spinal cord injury (SCI). Although an increased number of oligodendrocyte progenitor cells (OPCs) is observed in the injured spinal cord, they fail to convert into mature oligodendrocytes. However, little is known about the underlying mechanism. ⋯ When TNF-α or TNF-R1 was neutralized with antibody, the effect of reactive astrocyte-conditioned medium or recombinant TNF-α protein on OPC differentiation was markedly attenuated. In addition, reactive astrocyte-conditioned medium was also shown to induce OPC apoptosis. All these findings provide the first evidence that reactive astrocytes release TNF-α to inhibit OPC survival and prevent them from differentiating into mature oligodendrocytes, suggesting a mechanism for the failure of remyelination after SCI.