Establishment of an ideal time window model in hypothermic-targeted temperature management after traumatic brain injury in rats
BRAIN RESEARCH
Authors: Zhao, Wan-Yong; Chen, Shao-Bo; Wang, Jing-Jing; Xu, Chao; Zhao, Ming-Liang; Dong, Hua-Jiang; Liang, Hai-Qian; Li, Xiao-Hong; Tu, Yue; Zhang, Sai; Chen, Chong; Sun, Hong-Tao
Abstract
Although hypothermic-targeted temperature management (HTTM) holds great potential for the treatment of traumatic brain injury (TBI), translation of the efficacy of hypothermia from animal models to TBI patients has no entire consistency. This study aimed to find an ideal time window model in experimental rats which was more in accordance with clinical practice through the delayed HTTM intervention. Sprague-Dawley rats were subjected to unilateral cortical contusion injury and received therapeutic hypothermia at 15 mins, 2 h, 4 h respectively after TBI. The neurological function was evaluated with the modified neurological severity score and Morris water maze test. The brain edema and morphological changes were measured with the water content and H&E staining. Brain sections were immunostained with antibodies against DCX (a neuroblast marker) and GFAP (an astrocyte marker). The apoptosis levels in the ipsilateral hippocampi and cortex were examined with antibodies against the apoptotic proteins Bcl-2, Bax, and cleaved caspase-3 by the immunofluorescence and western blotting. The results indicated that each hypothermia therapy group could improve neurobehavioral and cognitive function, alleviate brain edema and reduce inflammation. Furthermore, we observed that therapeutic hypothermia increased DCX expression, decreased GFAP expression, upregulated Bcl-2 expression and downregulated Bax and cleaved Caspase-3 expression. The above results suggested that HTTM at 2 h or even at 4 h post injury revealed beneficial brain protection similarly, despite the best effect at 15 min post-injury. These findings may provide relatively ideal time window models, further making the following experimental results more credible and persuasive. (C) 2017 Elsevier B.V. All rights reserved.
In utero electroporation-based translating ribosome affinity purification identifies age-dependent mRNA expression in cortical pyramidal neurons
NEUROSCIENCE RESEARCH
Authors: Huang, Tianxiang; Nguyen, Lena H.; Lin, Tiffany, V; Gong, Xuan; Zhang, Longbo; Kim, Gi Bum; Sarkisian, Matthew R.; Breunig, Joshua J.; Bordey, Angelique
Abstract
We combined translating ribosome affinity purification (TRAP) with in utero electroporation (IUE), called iTRAP to identify the molecular profile of specific neuronal populations during neonatal development without the need for viral approaches and FACS sorting. We electroporated a plasmid encoding EGFP-tagged ribosomal protein L10a at embryonic day (E) 14-15 to target layer 2-4 cortical neurons of the somatosensory cortex. At three postnatal (P) ages-P0, P7, and P14-when morphogenesis occurs and synapses are forming, TRAP and molecular profiling was performed from electroporated regions. We found that ribosome bound (Ribo)-mRNAs from similar to 7300 genes were significantly altered over time and included classical neuronal genes known to decrease (e.g., Tbr1, Dcx) or increase (e.g., Eno2, Camk2a, Syn1) as neurons mature. This approach led to the identification of specific developmental patterns for Ribo-mRNAs not previously reported to be developmentally regulated in neurons, providing rationale for future examination of their role in selective biological processes. These include upregulation of Lynx1, Nrn1, Cntnap1 over time; downregulation of St8sia2 and Draxin; and bidirectional changes to Fkbp1b. iTRAP is a versatile approach that allows researchers to easily assess the molecular profile of specific neuronal populations in selective brain regions under various conditions, including overexpression and knockdown of target genes, and in disease settings. (C) 2018 Elsevier B.V. and Japan Neuroscience Society. All rights reserved.