Melatonin attenuates neuronal apoptosis through up-regulation of K+-Cl− cotransporter KCC2 expression following traumatic brain injury in rats

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• 作者：Haijian Wu ; Anwen Shao ; Mingfei Zhao ; Sheng Chen ; Jun Yu ; Jingyi Zhou ; Feng Liang ; Ligen Shi ; Brandon J. Dixon ; Zhen Wang ; Chenhan Ling ; Yuan Hong and Jianmin Zhang
• 刊名：Journal of Pineal Research
• 出版年：2016
• 出版时间：September 2016
• 年：2016
• 卷：61
• 期：2
• 页码：241-250
• 全文大小：757K
• ISSN：1600-079X

文摘

Traumatic brain injury (TBI) initiates a complex cascade of neurochemical and signaling changes that leads to neuronal apoptosis, which contributes to poor outcomes for patients with TBI. The neuron-specific K⁺–Cl⁻ cotransporter-2 (KCC2), the principal Cl⁻ extruder in adult neurons, plays an important role in Cl⁻ homeostasis and neuronal function. This present study was designed to investigate the expression pattern of KCC2 following TBI and to evaluate whether or not melatonin is able to prevent neuronal apoptosis by modulating KCC2 expression in a Sprague Dawley rat controlled cortical impact model of TBI. The time course study showed decreased mRNA and protein expression of KCC2 in the ipsilateral peri-core parietal cortex after TBI. Double immunofluorescence staining demonstrated that KCC2 is located in the plasma membrane of neurons. In addition, melatonin (10 mg/kg) was injected intraperitoneally at 5 minutes and repeated at 1, 2, 3, and 4 hours after brain trauma, and brain samples were extracted 24 hours after TBI. Compared to the vehicle group, melatonin treatment altered the down-regulation of KCC2 expression in both mRNA and protein levels after TBI. Also, melatonin treatment increased the protein levels of brain-derived neurotrophic factor (BDNF) and phosphorylated extracellular signal-regulated kinase (p-ERK). Simultaneously, melatonin administration ameliorated cortical neuronal apoptosis, reduced brain edema, and attenuated neurological deficits after TBI. In conclusion, our findings suggested that melatonin restores KCC2 expression, inhibits neuronal apoptosis and attenuates secondary brain injury after TBI, partially through activation of BDNF/ERK pathway.