Department of Neurology, Leonard M. Miller School of Medicine, University of Miami, Miami, FL 33136, USA; School of Biomedical Engineering, Indian Institute of Technology, Banaras Hindu University, Varanasi 221005, UP, India.
School of Biomedical Engineering, Indian Institute of Technology, Banaras Hindu University, Varanasi 221005, UP, India.
Life Sci. 2014 Apr 1;100(2):97-109. doi: 10.1016/j.lfs.2014.01.085. Epub 2014 Feb 14.
Aquaporin-4(AQP4) expression in the brain with relation to edema formation following focal cerebral ischemia was investigated. Studies have shown that brain edema is one of the significant factors in worsening stroke outcomes. While many mechanisms may aggravate brain injury, one such potential system may involve AQP4 up regulation in stroke patients that could result in increased edema formation. Post administration of melatonin following ischemic stroke reduces AQP4 mediated brain edema and confers neuroprotection.
An in-silico approach was undertaken to confirm effective melatonin-AQP4 binding. Rats were treated with 5mg/kg, i.p. melatonin or placebo at 30 min prior, 60 min post and 120 min post 60 min of middle cerebral artery occlusion (MCAO) followed by 24h reperfusion. Rats were evaluated for battery of neurological and motor function tests just before sacrifice. Brains were harvested for infarct size estimation, water content measurement, biochemical analysis, apoptosis study and western blot experiments.
Melatonin at 60 min post ischemia rendered neuroprotection as evident by reduction in cerebral infarct volume, improvement in motor and neurological deficit and reduction in brain edema. Furthermore, ischemia induced surge in levels of nitrite and malondialdehyde (MDA) were also found to be significantly reduced in ischemic brain regions in treated animals. Melatonin potentiated intrinsic antioxidant status, inhibited acid mediated rise in intracellular calcium levels, decreased apoptotic cell death and also markedly inhibited protein kinase C (PKC) influenced AQP4 expression in the cerebral cortex and dorsal striatum.
Melatonin confers neuroprotection by protein kinase C mediated AQP4 inhibition in ischemic stroke.
研究脑水肿形成时脑内水通道蛋白-4（AQP4）的表达与局灶性脑缺血的关系。研究表明，脑水肿是加重中风预后的重要因素之一。虽然许多机制可能加重脑损伤，但一个潜在的系统可能涉及中风患者的 AQP4 上调，从而导致脑水肿形成增加。缺血性中风后给予褪黑素可减少 AQP4 介导的脑水肿并发挥神经保护作用。
采用计算机模拟方法证实褪黑素与 AQP4 的有效结合。大鼠在大脑中动脉闭塞（MCAO） 60 分钟后，给予 5mg/kg，腹腔注射褪黑素或安慰剂，然后在 30 分钟前、60 分钟后和 120 分钟后给予治疗，再进行 24 小时再灌注。在处死前，对大鼠进行一系列神经和运动功能测试。取脑评估梗死面积、含水量测定、生化分析、凋亡研究和 Western blot 实验。
缺血后 60 分钟给予褪黑素可发挥神经保护作用，表现为脑梗死体积减小、运动和神经功能缺损改善以及脑水肿减少。此外，在缺血动物的缺血脑区，还发现诱导的亚硝酸盐和丙二醛（MDA）水平显著降低。褪黑素增强了内源性抗氧化状态，抑制了酸介导的细胞内钙水平升高，减少了细胞凋亡死亡，并显著抑制了蛋白激酶 C（PKC）影响大脑皮质和背侧纹状体的 AQP4 表达。
褪黑素通过蛋白激酶 C 介导的 AQP4 抑制在缺血性中风中发挥神经保护作用。
