Department of Neurology, Children's Hospital Boston, Boston, Massachusetts, United States of America.
PLoS One. 2013;8(3):e57148. doi: 10.1371/journal.pone.0057148. Epub 2013 Mar 11.
Neonatal seizures can be refractory to conventional anticonvulsants, and this may in part be due to a developmental increase in expression of the neuronal Na(+)-K(+)-2 Cl(-) cotransporter, NKCC1, and consequent paradoxical excitatory actions of GABAA receptors in the perinatal period. The most common cause of neonatal seizures is hypoxic encephalopathy, and here we show in an established model of neonatal hypoxia-induced seizures that the NKCC1 inhibitor, bumetanide, in combination with phenobarbital is significantly more effective than phenobarbital alone. A sensitive mass spectrometry assay revealed that bumetanide concentrations in serum and brain were dose-dependent, and the expression of NKCC1 protein transiently increased in cortex and hippocampus after hypoxic seizures. Importantly, the low doses of phenobarbital and bumetanide used in the study did not increase constitutive apoptosis, alone or in combination. Perforated patch clamp recordings from ex vivo hippocampal slices removed following seizures revealed that phenobarbital and bumetanide largely reversed seizure-induced changes in EGABA. Taken together, these data provide preclinical support for clinical trials of bumetanide in human neonates at risk for hypoxic encephalopathy and seizures.
新生儿癫痫发作可能对常规抗癫痫药物有抗药性，这在一定程度上可能是由于神经元 Na(+)-K(+)-2 Cl(-)共转运蛋白 NKCC1 在发育过程中的表达增加，以及在围产期 GABA A 受体的反常兴奋作用。新生儿癫痫发作最常见的原因是缺氧性脑病，在这里，我们在新生儿缺氧诱导癫痫发作的既定模型中表明，NKCC1 抑制剂布美他尼与苯巴比妥联合使用比单独使用苯巴比妥更有效。一种灵敏的质谱分析显示，布美他尼在血清和大脑中的浓度与剂量呈依赖性，缺氧性癫痫发作后皮质和海马中的 NKCC1 蛋白表达短暂增加。重要的是，研究中使用的低剂量苯巴比妥和布美他尼单独或联合使用均不会增加组成型细胞凋亡。癫痫发作后取出的离体海马切片中的穿孔贴附式膜片钳记录显示，苯巴比妥和布美他尼在很大程度上逆转了癫痫发作引起的 EGABA 的变化。总之，这些数据为在有缺氧性脑病和癫痫发作风险的人类新生儿中进行布美他尼临床试验提供了临床前支持。
