Journal of neurotrauma
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Journal of neurotrauma · Jul 2022
Correlation of blast-induced tympanic membrane perforation with peripheral cochlear synaptopathy.
The auditory organs, including the tympanic membrane, cochlea, and central auditory pathway, are the most fragile components of the human body when exposed to blast overpressure. Tympanic membrane perforation (TMP) is the most frequent symptom in blast-exposed patients. The impact of TMP on the inner ear and central auditory system, however, is not fully understood. ⋯ A decrease in the number of excitatory central synapses labeled by VGLUT-1 in the cochlear nucleus was observed, however, regardless of the absence or presence of TMP. Our findings suggest that blast-induced TMP mitigates peripheral cochlear synaptic disruption but leaves the central auditory synapses unaffected, indicating that central synaptic disruption is independent of TMP and peripheral cochlear synaptic disruption. Synaptic deterioration in the peripheral and central auditory systems can contribute to the promotion of blast-induced hearing impairment, including abnormal auditory perception.
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Journal of neurotrauma · Jul 2022
Randomized Controlled TrialPlasma Neurofilament Light and Glial Fibrillary Acidic Protein Levels over Thirty Days in a Porcine Model of Traumatic Brain Injury.
To establish the clinical relevance of porcine model of traumatic brain injury (TBI) using the plasma biomarkers of injury with diffusion tensor imaging (DTI) over 30 days, we performed a randomized, blinded, pre-clinical trial using Yorkshire pigs weighing 7-10 kg. Twelve pigs were subjected to Sham injury (n = 5) by skin incision or TBI (n = 7) by controlled cortical impact. Blood samples were collected before the injury, then at approximately 5-day intervals until 30 days. ⋯ Porcine model of TBI replicates the acute increase in plasma biomarkers seen in clinical TBI. Further, long term white matter injury is confirmed in the areas such as the splenium and corona radiata. However, future study stratifying severe and mild TBI, as well as comparison with other subtypes of TBI such as diffuse axonal injury, may be warranted.
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Journal of neurotrauma · Jul 2022
EditorialDefining an Approach to Monitoring Brain Health in Individuals Exposed to Repetitive Head Impacts: Lessons Learned from Radiation Safety.
Recently, there has been increased concern over the effect of repetitive head impacts (RHIs, both concussive and subconcussive impacts) on long-term brain health. This concern has led researchers and policy makers to consider establishing RHI thresholds in order to mitigate the potential long-term effects of RHI exposure. However, the concept of thresholding relies on twin streams of information: 1) biomedical research relevant to the short and long-term risks of exposure to RHIs, and 2) societal standards for "acceptable risk." In the case of RHI, these streams of information have not been cogently combined to inform sensible policy making. In the current editorial, we discuss how the history of radiation safety provides an instructive example of an approach to ford these two streams to derive actionable clinically relevant policies surrounding RHI exposures.
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Journal of neurotrauma · Jul 2022
Glucocorticoid Receptor Overexpression in the Dorsal Hippocampus Attenuates Spatial Learning and Synaptic Plasticity Deficits Following Pediatric Traumatic Brain Injury.
Traumatic brain injury (TBI) in children <4 years of age leads to long-term deficits in cognitive and learning abilities that can persist or even worsen as these children age into adolescence. In this study, the role of glucocorticoid receptor (GR) function in the dorsal hippocampus (DH) in hippocampal-dependent cognitive function and synaptic plasticity were assessed following injury to the 11-day-old rat. Brain injury produced significant impairments in spatial learning and memory in the Morris water maze in male and female rats at 1-month post-injury (adolescence), which was accompanied by impairments in induction and maintenance of long-term potentiation (LTP) in the CA1 region of the DH. ⋯ Lentiviral transfection of the human GR (hGR) in the DH improved spatial learning and memory in the Morris water maze and attenuated LTP deficits following TBI. GR overexpression in the DH was also associated with a significant increase in the mRNA expression levels of sgk1, and the glutamate receptor subunits GluA1 and GluA2 within the hippocampus. Overall, these findings support an important role for dorsal hippocampal GR function in learning and memory deficits following pediatric TBI and suggest that these effects may be related to the regulation of glutamate receptor subunit expression in the DH.
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Journal of neurotrauma · Jul 2022
Repetitive mild traumatic brain injury in an awake, unanesthetized mouse model of perinatal nicotine exposure produces transient novelty-seeking and depression-like behaviors.
Attention deficit hyperactivity disorder (ADHD) can be a risk factor for repetitive mild traumatic brain injury (mTBI) or concussions such as those that can occur in contact sports. Individuals with ADHD also appear to have a higher risk of poor neurocognitive outcomes after repetitive mTBI. Findings from clinical studies examining the interactions between ADHD and repetitive mTBI vary, likely because of variabilities in experimental design and outcome measures. ⋯ Before the repetitive mTBI, the mice in the PNE group showed attention deficit, which persisted after the mTBI. The mice in the control (non-PNE) group showed a transient attention deficit after the repetitive mTBI but not any of the other behavioral changes seen in the PNE-mTBI group. These findings from an unanesthetized mouse model with a pre-existing condition show that ADHD and repetitive mTBI together contribute to transient novelty-seeking and depression-like behavior supporting the notion that untreated ADHD may be a risk factor for poor neurocognitive outcomes after concussions.