Journal of neurotrauma
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Journal of neurotrauma · Jan 2012
Blast-induced tinnitus and hearing loss in rats: behavioral and imaging assays.
Abstract The current study used a rat model to investigate the underlying mechanisms of blast-induced tinnitus, hearing loss, and associated traumatic brain injury (TBI). Seven rats were used to evaluate behavioral evidence of tinnitus and hearing loss, and TBI using magnetic resonance imaging following a single 10-msec blast at 14 psi or 194 dB sound pressure level (SPL). The results demonstrated that the blast exposure induced early onset of tinnitus and central hearing impairment at a broad frequency range. ⋯ No significant microstructural changes found in the corpus callosum indicates that the currently adopted blast exposure mainly exerts effects through the auditory pathways rather than through direct impact onto the brain parenchyma. The results showed that this animal model is appropriate for investigation of the mechanisms underlying blast-induced tinnitus, hearing loss, and related TBI. Continued investigation along these lines will help identify pathology with injury/recovery patterns, aiding development of effective treatment strategies.
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Journal of neurotrauma · Jan 2012
Identification of plasma biomarkers of TBI outcome using proteomic approaches in an APOE mouse model.
The current lack of diagnostic and prognostic biomarkers for traumatic brain injury (TBI) confounds treatment and management of patients and is of increasing concern as the TBI population grows. We have generated plasma proteomic profiles from mice receiving TBI by controlled cortical impact at either 1.3 mm or 1.8 mm depth, comparing these against those of sham injured-animals to identify plasma biomarkers specific to mild or severe TBI at 24 hours, 1 month, or 3 months post-injury. To identify possible prognostic biomarkers, we used apolipoprotein E (APOE)3 and APOE4 transgenic mice, which demonstrate relatively favorable and unfavorable outcomes respectively, following TBI. ⋯ These preliminary data clearly demonstrate plasma protein changes that are not only injury dependent but also interaction dependent. Importantly, these results demonstrate the presence of TBI-dependent and interaction-dependent plasma proteins at a 3-month time point, which is a considerable time post-injury in the mouse model, and will potentially be of significance for combat veterans receiving assessment at extended periods post-injury. Furthermore, our identification of clusters of functionally related proteins indicates disturbance of particular biological modules, which potentially increases their value beyond that of solitary biomarkers.
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Journal of neurotrauma · Jan 2012
Lithium ameliorates neurodegeneration, suppresses neuroinflammation, and improves behavioral performance in a mouse model of traumatic brain injury.
Although traumatic brain injury (TBI) is recognized as one of the leading causes of death from trauma to the central nervous system (CNS), no known treatment effectively mitigates its effects. Lithium, a primary drug for the treatment of bipolar disorder, has been known to have neuroprotective effects in various neurodegenerative conditions such as stroke. Until this study, however, it has not been investigated as a post-insult treatment for TBI. ⋯ As for behavioral outcomes, lithium treatment reduced anxiety-like behavior in an open-field test, and improved short- and long-term motor coordination in rotarod and beam-walk tests. Lithium robustly increased serine phosphorylation of glycogen synthase kinase-3β (GSK-3β), suggesting that the underlying mechanisms responsible for lithium's protective effects are triggered by increasing phosphorylation of this kinase and thereby inhibiting its activity. Our results support the notion that lithium has heretofore unrecognized capacity to mitigate the neurodegenerative effects and improve functional outcomes in TBI.
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Journal of neurotrauma · Jan 2012
Low-level laser light therapy improves cognitive deficits and inhibits microglial activation after controlled cortical impact in mice.
Low-level laser light therapy (LLLT) exerts beneficial effects on motor and histopathological outcomes after experimental traumatic brain injury (TBI), and coherent near-infrared light has been reported to improve cognitive function in patients with chronic TBI. However, the effects of LLLT on cognitive recovery in experimental TBI are unknown. We hypothesized that LLLT administered after controlled cortical impact (CCI) would improve post-injury Morris water maze (MWM) performance. ⋯ Little or no effect of LLLT on post-injury cognitive function was observed using the other doses, a 4-h administration time point and 7-day administration of 60 J/cm². No effect of LLLT (60 J/cm² open craniotomy) was observed on post-injury motor function (days 1-7), brain edema (24 h), nitrosative stress (24 h), or lesion volume (14 days). Although further dose optimization and mechanism studies are needed, the data suggest that LLLT might be a therapeutic option to improve cognitive recovery and limit inflammation after TBI.
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Journal of neurotrauma · Jan 2012
Minocycline restores olfactory bulb volume and olfactory behavior after traumatic brain injury in mice.
Permanent olfactory dysfunction can often arise after traumatic brain injury (TBI) and while one of the main causes is the immediate loss of neurons in the olfactory bulb (OB), the emergent neuroinflammatory environment following TBI may further promote OB deterioration. Therefore, we examined the effects of acute anti-inflammatory treatment with minocycline on post-TBI olfactory behavior and on OB surface. The mouse model of closed-head injury by mechanical percussion was applied to anesthetized Swiss mice. ⋯ Additionally, substantial post-TBI OB atrophy was observed that was strongly correlated with the behavioral impairment. Minocycline was able to attenuate both the olfactory lesions and corresponding functional deficit in the short and long term. These results emphasize the potential role of minocycline as a promising neuroprotective agent for the treatment of TBI-related olfactory bulb lesions and deficits.