Das Arabinda, McDowell Misty, O'Dell Casey M, Busch Megan E, Smith Joshua A, Ray Swapan K, Banik Naren L
Department of Neurosciences, Medical University of South Carolina, 96 Jonathan Lucus Street, Charleston, SC 29425, USA.
Neurochem Res. 2010 Dec;35(12):2175-83. doi: 10.1007/s11064-010-0321-1. Epub 2010 Dec 3.
Injection of rats with kainic acid (KA), a non-N-methyl-D-aspartate (NMDA) type glutamate receptor agonist, induces recurrent (delayed) convulsive seizures and subsequently hippocampal neurodegeneration, which is reminiscent of human epilepsy. The protective effect of anti-epileptic drugs on seizure-induced neuronal injury is well known; however, molecular basis of this protective effect has not yet been elucidated. In this study, we investigated the effect and signaling mediators of voltage-gated Na(+) channel blockers (Lamotrigine, Rufinamide, Oxcarbazepine, Valproic Acid, and Zonisamide) on KA-induced apoptosis in rat primary hippocampal neurons. Exposure of hippocampal neurons to 10 μM KA for 24 h caused significant increases in morphological and biochemical features of apoptosis, as determined by Wright staining and ApopTag assay, respectively. Analyses showed increases in expression and activity of cysteine proteases, production of reactive oxygen species (ROS), intracellular free [Ca(2+)], and Bax:Bcl-2 ratio during apoptosis. Cells exposed to KA for 15 min were then treated with Lamotrigine, Rufinamide, Oxcarbazepine, Valproic Acid, or Zonisamide. Post-treatment with one of these anti-epileptic drugs (500 nM) attenuated production of ROS and prevented apoptosis in hippocampal neurons. Lamotrigine, Rufinamide, and Oxcarbazepine appeared to be less protective when compared with Valproic Acid or Zonisamide. This difference may be due to blockade of T-type Ca(2+) channels also by Valproic Acid and Zonisamide. Our findings thus suggest that the anti-epileptic drugs that block both Na(+) channels and Ca(2+) channels are significantly more effective than agents that block only Na(+) channels for attenuating seizure-induced hippocampal neurodegeneration.
给大鼠注射红藻氨酸(KA),一种非N - 甲基 - D - 天冬氨酸(NMDA)型谷氨酸受体激动剂,会诱发反复(延迟)惊厥性癫痫发作,随后导致海马神经变性,这与人类癫痫相似。抗癫痫药物对癫痫发作诱导的神经元损伤的保护作用是众所周知的;然而,这种保护作用的分子基础尚未阐明。在本研究中,我们研究了电压门控钠通道阻滞剂(拉莫三嗪、卢非酰胺、奥卡西平、丙戊酸和唑尼沙胺)对KA诱导的大鼠原代海马神经元凋亡的影响及信号转导介质。分别通过瑞氏染色和ApopTag检测法确定,将海马神经元暴露于10 μM KA 24小时会导致凋亡的形态学和生化特征显著增加。分析表明,凋亡过程中半胱氨酸蛋白酶的表达和活性增加、活性氧(ROS)生成、细胞内游离[Ca²⁺]以及Bax:Bcl - 2比值增加。然后将暴露于KA 15分钟的细胞用拉莫三嗪、卢非酰胺、奥卡西平、丙戊酸或唑尼沙胺处理。用这些抗癫痫药物之一(500 nM)进行后处理可减少ROS生成并防止海马神经元凋亡。与丙戊酸或唑尼沙胺相比,拉莫三嗪、卢非酰胺和奥卡西平的保护作用似乎较小。这种差异可能是由于丙戊酸和唑尼沙胺也阻断了T型钙通道。因此,我们的研究结果表明,对于减轻癫痫发作诱导的海马神经变性,同时阻断钠通道和钙通道的抗癫痫药物比仅阻断钠通道的药物显著更有效。