Tianjin Medical Journal

Tianjin Medical Journal

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Mild hypothermia facilitates the long-term survival and maturation of hippocampal newborn neurons after traumatic brain injury in rats

WANG Jing1, XU Chao1, LI Xiao-hong1, TU Yue1, CHEN Chong1, MA Tie-zhu1, WANG Li-na1, ZHU Xu1, REN Ji-bin1, XU Zi-ning1, YANG Hui-yun2, ZHANG Sai1△   

  1. 1 Tianjin Key Laboratory of Neurotrauma Repair, Institute of Traumatic Brain Injury and Neuroscience, the Affiliated Hospital of Logistics University of Chinese People’s Armed Police Forces, Tianjin 300162, China; 2 School of Biomedical Engineering and Technology of Tianjin Medical University △Corresponding Author E-mail: zhangsai718@vip.126.com
  • Published:2018-07-15 Online:2018-07-15

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Abstract: Objective To investigate the effect of mild hypothermia (MHT) in long-term survival and maturation of newborn neurons in the dentate gyrus (DG) of hippocampus after traumatic brain injury (TBI) in rats. Methods Fifty-nine adult Sprague-Dawley (SD) rats were randomly divided into the sham-injured group (n=15), TBI group (n=22) and TBI+ MHT group (n=22). The TBI rat model was established with hydraulic impact brain damage instrument, and the pressure was set at 2.0 atm (1 atm=101.325 kPa). The rats in TBI +MHT group were received MHT after injury, and the rectal target temperature was 33.5 ℃ maintaining 4 h, and then raised the temperature slowly within 1.5 h to 37 ℃. The Morris water maze, modified neurological severity scores (mNSS) and immunofluorescence staining were used at the corresponding time points to observe functional recovery of nervous system and long-term survival and maturation of newborn neurons in hippocampus. Results Morris water maze tests showed that the escape latency was significantly decreased, and the number of platform crossings and the time stayed in the target quadrant were increased at 4 weeks after injury in TBI+MHT group compared with those of TBI group (P＜0.05). Compared with TBI group, mNSS was significantly decreased at 1, 2 and 4 weeks after injury in TBI+MHT group (P＜0.01). Compared with sham group，BrdU-positive cells and BrdU/NeuN doublelabeled cells in rat hippocampal DG were significantly increased at 1, 4 and 8 weeks after injury in TBI group and TBI+MHT group (P＜0.05), and which were increased more obviously in TBI + MHT group than those of TBI group (P＜0.05). Furthermore, the BrdU/NeuN double-labeled cells were further increased at 4 weeks and 8 weeks after injury in TBI+MHT group, and which were decreased in TBI group compared with 1 week after injury (P＜0.05). Conclusion MHT could facilitate not only long-term survival but also maturation of newborn neurons after TBI, and promote the functional recovery of nervous system.

Key words: hypothermia, induced, craniocerebral trauma, hippocampus, neurons