Journal of neurotrauma
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Journal of neurotrauma · Apr 2011
Concussive brain trauma in the mouse results in acute cognitive deficits and sustained impairment of axonal function.
Concussive brain injury (CBI) accounts for approximately 75% of all brain-injured people in the United States each year and is particularly prevalent in contact sports. Concussion is the mildest form of diffuse traumatic brain injury (TBI) and results in transient cognitive dysfunction, the neuropathologic basis for which is traumatic axonal injury (TAI). To evaluate the structural and functional changes associated with concussion-induced cognitive deficits, adult mice were subjected to an impact on the intact skull over the midline suture that resulted in a brief apneic period and loss of the righting reflex. ⋯ At 1 and 3 days post-injury, intra-axonal accumulation of amyloid precursor protein in the corpus callosum and cingulum was accompanied by neurofilament dephosphorylation, impaired transport of Fluoro-Gold and synaptophysin, and deficits in axonal conductance. Importantly, deficits in retrograde transport and in action potential of myelinated axons continued to be observed until 14 days post-injury, at which time axonal degeneration was apparent. These data suggest that despite recovery from acute cognitive deficits, concussive brain trauma leads to axonal degeneration and a sustained perturbation of axonal function.
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Journal of neurotrauma · Apr 2011
Spinal cord injuries induce changes in CB1 cannabinoid receptor and C-C chemokine expression in brain areas underlying circuitry of chronic pain conditions.
Due to their involvement in neuro-modulatory processes, the endogenous cannabinoid system and chemokine network, which were shown to interact which each other, are potential key elements in the cascades underlying central neuropathic pain development after spinal cord injury (SCI). Expression profiles of cannabinoid receptor type-1 (CB(1)), and of the chemokines chemokine ligand 2 (C-C motif ) (CCL2), chemokine ligand 3 (C-C motif ) (CCL3), plus their main receptors CCR2 and CCR1, were investigated in brain regions related to pain, emotion, learning, and memory in a rat SCI paradigm of post-traumatic neuropathic pain. Immunoreactivity (IR) was investigated 7 days and 42 days after sham operation, and moderate (100-kdyn), and severe (200-kdyn) thoracic spinal cord contusion lesions. ⋯ Double-labeling revealed partial co-expression of CB(1) with the pain-related vanilloid receptor transient receptor potential vanilloid receptor 1 (TRPV1), and chemokines (CCL2 and CCL3). These chemokines were induced in the PAG, thalamus, and HC, especially in the chronic time course after severe SCI. Thus interactions of CB(1), C-C chemokines, and TRPV1 likely play a role in SCI-induced plastic changes in the brain, underlying emotional-affective pain responses and central pain development after spinal cord lesions.
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Journal of neurotrauma · Mar 2011
Development of a chronic cervical cord compression model in rat: changes in the neurological behaviors and radiological and pathological findings.
Cervical myelopathy is caused by chronic segmental compression of the spinal cord because of degenerative changes of the spine. However, the exact mechanisms of chronic cervical cord compression are not fully understood. The purpose of this study was to validate a new animal model of chronic cervical cord compression capable of reproducing the clinical course without laminectomy in rats. ⋯ In histological sections, the spinal cord was compressed along the entire circumference at 12 months after initiating CCS. The number of ventral neurons was decreased, and the white matter showed wallerian degeneration. This model might reproduce characteristic features of clinical chronic cervical cord compression, including progressive motor and sensory disturbances after a latency period and insidious neuronal loss, and represents chronic compression of the cervical spinal cord in humans.
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Journal of neurotrauma · Mar 2011
A model of low-level primary blast brain trauma results in cytoskeletal proteolysis and chronic functional impairment in the absence of lung barotrauma.
Shock-wave exposure from improvised explosive devices (IEDs) has been implicated as a possible contributing factor to neurological impairment reported in combat veterans. However, evidence-based substantiation of this implication, particularly for low-level exposure in the absence of external signs of trauma, remain elusive. Accordingly, we constructed an open-ended shock tube producing a short-duration, low-amplitude shockwave. ⋯ Evoked compound action potential (CAP) recordings from the corpus callosum showed a significant increase in the duration of CAP responses at 14 and 30 days post-injury, and a gradual depression in the unmyelinated fiber amplitude. Shielding the head attenuated αII-spectrin cytoskeletal breakdown, thus directly implicating low-level shock-wave exposure as a cause of brain injury in the rat. Despite anatomical and scaling differences in rats compared to humans, the results suggest the potential for undiagnosed traumatic brain pathologies occurring in combat veterans following shock-wave exposure.
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Journal of neurotrauma · Mar 2011
Glucagon protects against impaired NMDA-mediated cerebrovasodilation and cerebral autoregulation during hypotension after brain injury by activating cAMP protein kinase A and inhibiting upregulation of tPA.
Outcome of traumatic brain injury (TBI) is impaired by hyperglycemia, hypotension, and glutamate, and improved by insulin. Insulin reduces glutamate concentration, making it uncertain whether its beneficial effect accrues from euglycemia. Glucagon decreases CNS glutamate, lessens neuronal cell injury, and improves neurological scores in mice after TBI. ⋯ Co-administration of the PKA antagonist Rp 8Br cAMPs prevented glucagon-mediated preservation of NMDA-mediated dilation after FPI. The pKA agonist Sp 8Br cAMPs prevented impairment of NMDA-induced dilation. These data indicate that glucagon protects against impaired cerebrovasodilation by upregulating cAMP, which decreases release of tPA, suggesting that it may provide neuroprotection when given after TBI, or prior to certain neurosurgical or cardiac interventions in which the incidence of perioperative ischemia is high.