Effects of transection of cervical sympathetic trunk on cognitive function of traumatic brain injury rats

Abstract

Juan Long,1 Chunjing He,1 Hong Dai,2 Xinguo Kang,1 Jinfeng Zou,1 Shengli Ye,1 Qian Yu21Department of Pain, Guizhou Province People‘s Hospital, Guiyang, People’s Republic of China; 2Department of Neurology, Guizhou Province People‘s Hospital, Guiyang, People’s Republic of ChinaObjective: To observe the effects of transection of cervical sympathetic trunk (TCST) on the cognitive function of traumatic brain injury (TBI) rats and the potential mechanisms.Methods: A total of 288 adult male SD rats were divided into 3 groups using a random number table: TBI group (n=96), TBI + TCST group (n=96) and Sham group (n=96). The water maze test was performed before TBI (T0) and at day 1 (T1), day 2 (T2), day 3 (T3), 1 week (T4), 2 weeks (T5), 6 weeks (T6) and 12 weeks (T7) after TBI. The levels of α1-adrenergic receptors (α1-ARs), α2-adrenergic receptors (α2-ARs), toll-like receptor 4 (TLR-4) and P38 in hippocampi were detected by real-time PCR. Hippocampal P38 expression was assayed by Western blot. The expressions of interleukin-6 (IL-6), tumor necrosis factor (TNF-α) and brain-derived neurotrophic factor (BDNF) were examined by immunohistochemistry. Noradrenaline (NE) expression in plasma was evaluated by ELISA. The respiratory control ratio (RCR) of brain mitochondria was detected using a Clark oxygen electrode.Results: TCST effectively improved the cognitive function of TBI rats. TCST significantly inhibited sympathetic activity in the rats and effectively inhibited inflammatory responses. The expression of BDNF at T1-T6 in TBI+TCST group was higher than that in TBI group (P<0.05). Furthermore, P38 expression was inhibited more effectively in TBI+TCST group (P<0.05), than in TBI group (P<0.05), and the RCR of the brain was significantly higher in TBI+TCST group than in TBI group (P<0.05).Conclusions: TCST can enhance cognitive function in TBI rats by inhibiting sympathetic activity, reducing inflammatory responses and brain edema, upregulating BDNF and improving brain mitochondrial function.Keywords: traumatic brain injury, transection of the cervical sympathetic trunk, sympathetic nervous system, inflammatory response, mitochondrial function

Keywords

• Traumatic brain injury
• Transection of the cervical sympathetic trunk
• Sympathetic nervous system
• Inflammatory response
• Mitochondrial function