Neural Regeneration Research ›› 2018, Vol. 13 ›› Issue (10): 1753-1758.doi: 10.4103/1673-5374.238618

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Cognitive impairment after traumatic brain injury is associated with reduced long-term depression of excitatory postsynaptic potential in the rat hippocampal dentate gyrus

Bao-Liang Zhang, Yue-Shan Fan, Ji-Wei Wang, Zi-Wei Zhou, Yin-Gang Wu, Meng-Chen Yang, Dong-Dong Sun, Jian-Ning Zhang   

  1. Department of Neurosurgery, Tianjin Medical University General Hospital; Tianjin Neurological Institute; Key Laboratory of Post-trauma Neuro-repair and Regeneration in Central Nervous System, Ministry of Education; Tianjin Key Laboratory of Injuries, Variations and Regeneration of Nervous System, Tianjin, China
  • Received:2018-07-06 Online:2018-10-15 Published:2018-10-15
  • Contact: Jian-Ning Zhang, PhD, MD,jianningzhang@hotmail.com.
  • Supported by:

    This study was supported by the National Natural Science Foundation of China, No. 81330029, 81501057; the Natural Science Foundation of Tianjin of China, No. 17JCQNJC12000; the Tianjin Medical University General Hospital Funding in China, No. ZYYFY2016014.

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Abstract:

Traumatic brain injury can cause loss of neuronal tissue, remote symptomatic epilepsy, and cognitive deficits. However, the mechanisms underlying the effects of traumatic brain injury are not yet clear. Hippocampal excitability is strongly correlated with cognitive dysfunction and remote symptomatic epilepsy. In this study, we examined the relationship between traumatic brain injury-induced neuronal loss and subsequent hippocampal regional excitability. We used hydraulic percussion to generate a rat model of traumatic brain injury. At 7 days after injury, the mean modified neurological severity score was 9.5, suggesting that the neurological function of the rats was remarkably impaired. Electrophysiology and immunocytochemical staining revealed increases in the slope of excitatory postsynaptic potentials and long-term depression (indicating weakened long-term inhibition), and the numbers of cholecystokinin and parvalbumin immunoreactive cells were clearly reduced in the rat hippocampal dentate gyrus. These results indicate that interneuronal loss and changes in excitability occurred in the hippocampal dentate gyrus. Thus, traumatic brain injury-induced loss of interneurons appears to be associated with reduced long-term depression in the hippocampal dentate gyrus.

Key words: nerve regeneration, long-term depression, traumatic brain injury, hippocampus, interneurons, excitability, dentate gyrus, parvalbumin, cholecystokinin, electrophysiology, quantification, neural regeneration