Journal of neurotrauma
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Cortical spreading depression (CSD) has been described after moderate-to-severe traumatic brain injury (TBI). It is uncertain, however, whether CSD occurs after mild, concussive TBI and whether it relates to brain pathology and functional outcome. Male C57BL6/J mice (n = 62) were subjected to closed head TBI with a 25 g weight (n = 11), 50 g weight (n = 45), or sham injury (n = 6). ⋯ Compared with mice without a CSD, mice with a CSD had significantly more microbleeds in the traumatized hemisphere (p < 0.05, each) and showed impaired functional recovery (p < 0.05). Incidence of CSD after mild TBI depended on impact severity and was associated with histological and behavioral outcomes. These observations indicate that concussive CSD may serve as viable marker for concussion severity and provide novel avenues for outcome prediction and therapeutic decision making.
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Journal of neurotrauma · Apr 2019
Circular Ribonucleic Acid Expression Profile in Mouse Cortex after Traumatic Brain Injury.
Traumatic brain injury (TBI) causes high rates of worldwide death and morbidity because of the complex secondary injury cascade. Circular ribonucleic acid (RNA) (circRNA), a type of RNA that forms a covalently closed continuous loop, may be involved in the regulation of secondary injury because it is expressed widely in the brain and contributes to a large class of post-transcriptional regulators. Deep RNA sequencing (RNA-seq) and bioinformatic analysis were performed to investigate the expression profile and function of circRNAs in the mouse cortex after controlled cortical impact (CCI). ⋯ In addition to five optimal circRNA-miRNA-mRNA pairs were analyzed, circRNA_16895-miRNA myosin-10 (Myo 10) was predicted to regulate fragment crystallizable gamma receptors (FcγR)-mediated phagocytosis pathway. Four circRNAs were selected for quantitative real-time polymerase chain reaction analysis to validate the sequencing data. Our results provide promising functions of circRNAs aberrantly expressed in TBI to explore molecular mechanisms and potential therapeutic targets for its therapy.
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Journal of neurotrauma · Apr 2019
Sex Differences in Acute Neuroinflammation after Experimental Traumatic Brain Injury Are Mediated by Infiltrating Myeloid Cells.
The inflammatory response to moderate-severe controlled cortical impact (CCI) in adult male mice has been shown to exhibit greater glial activation compared with age-matched female mice. However, the relative contributions of resident microglia and infiltrating peripheral myeloid cells to this sexually dimorphic neuroinflammatory responses remains unclear. Here, 12-week-old male and female C57Bl/6 mice were subjected to sham or CCI, and brain samples were collected at 1, 3, or 7 days post-injury for flow cytometry analysis of cytokines, reactive oxygen species (ROS), and phagocytosis in resident microglia (CD45intCD11b+) versus infiltrating myeloid cells (CD45hiCD11b+). ⋯ However, across these functions, infiltrating myeloid cells were significantly more reactive than resident microglia. Female CCI mice also had improved motor function at 1 day post-injury compared with male mice. Thus, we conclude that sexually dimorphic responses to moderate-severe CCI result from the rapid activation and infiltration of pro-inflammatory myeloid cells to brain in male, but not female, mice.
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Journal of neurotrauma · Apr 2019
Role of Nogo Receptor-1 for Recovery of Balance, Cognition, and Emotion after Mild Traumatic Brain Injury in Mice.
Mild traumatic brain injury (mTBI) constitutes 75 ∼ 90% of all TBI cases and causes various physical, cognitive, emotional, and other psychological symptoms. Nogo receptor 1 (NgR1) is a regulator of structural brain plasticity during development and in adulthood. Here, we used mice that, in the absence of doxycycline, overexpress NgR1 in forebrain neurons (MemoFlex) to determine the role of NgR1 in recovery from mTBI with respect to balance, cognition, memory, and emotion. ⋯ We found that inability to downregulate NgR1 significantly impairs recovery from mTBI-induced impairments. When the NgR1 transgene was turned off, recovery was similar to that of WT mice. The results suggest that the ability to regulate NgR1 signaling is needed for optimal recovery of motor coordination and balance, spatial memory, cognition, and emotional functions after mTBI.