Gupta R C, Milatovic D, Dettbarn W D
Toxicology Department, Breathitt Veterinary Center, Murray State University, Hopkinsville, KY, USA.
Neurotoxicology. 2001 Apr;22(2):271-82. doi: 10.1016/s0161-813x(01)00013-4.
Status epilepticus (SE)-induced neuronal injury may involve excitotoxicity, energy impairment and increased generation of reactive oxygen species (ROS). Potential treatment therefore should consider agents that protect mitochondrial function and ROS scavengers. In the present study, we examined whether the spin trapping agent N-tertbutyl-alpha-phenylnitrone (PBN) and the antioxidant vitamin E (DL-alpha-tocopherol) protect levels of high-energy phosphates during SE. In rats, SE was induced by either of two inhibitors of acetylcholinesterase (AChE), the organophosphate diisopropylphosphorofluoridate (DFP, 1.25 mg/kg, sc)- or the carbamate carbofuran (1.25 mg/kg, sc). Rats were sacrificed 1 h or 3 days after onset of seizures by head-focused microwave (power, 10 kW; duration 1.7 s) and levels of the energy-rich phosphates adenosine triphosphate (ATP) and phosphocreatine (PCr) and their metabolites adenosine diphosphate (ADP) and adenosine monophosphate (AMP), and creatine (Cr), respectively, were determined in the cortex, amygdala and hippocampus. Within 1 h of seizure activity, marked declines were seen in ATP (34-60%) and PCr (25-52%). Total adenine nucleotides (TAN = ATP + ADP + AMP) and total creatine compounds (TCC = PCr + Cr) were also reduced (TAN 38-60% and TCC 25-47%). No changes in ATP/AMP ratio were seen. Three days after the onset of seizures, recovery of ATP and PCr was significant in the amygdala and hippocampus, but not in the cortex. Pretreatment of rats with PBN (200 mg/kg, ip, in a single dose), 30 min before DFP or carbofuran administration, prevented induced seizures and partially prevented depletion of high-energy phosphates. Pretreatment with the natural antioxidant vitamin E (100 mg/kg, ip/day for 3 days), partially prevented loss of high energy phosphates without affecting seizures. In controls, citrulline, a product of nitric oxide synthesis, was found to be highest in the amygdala, followed by hippocampus, and lowest in the cortex. DFP- or carbofuran-induced seizures caused elevation of citrulline levels seven- to eight-fold in the cortex and three- to four-fold in the amygdala and hippocampus. These results suggest a close relationship between SE, excitotoxicity and energy metabolism. The involvement of oxidative stress is supported by the findings that DFP and carbofuran trigger an excessive nitric oxide (NO) production in the seizure relevant regions of the brain.
癫痫持续状态（SE）诱导的神经元损伤可能涉及兴奋性毒性、能量损伤以及活性氧（ROS）生成增加。因此，潜在的治疗方法应考虑使用保护线粒体功能的药物和ROS清除剂。在本研究中，我们检测了自旋捕捉剂N-叔丁基-α-苯基硝酮（PBN）和抗氧化剂维生素E（DL-α-生育酚）是否能在SE期间保护高能磷酸盐水平。在大鼠中，通过两种乙酰胆碱酯酶（AChE）抑制剂之一诱导SE，即有机磷酸酯二异丙基磷酰氟（DFP，1.25 mg/kg，皮下注射）或氨基甲酸酯呋喃丹（1.25 mg/kg，皮下注射）。在癫痫发作开始后1小时或3天，通过头部聚焦微波（功率10 kW；持续时间1.7 s）处死大鼠，并分别测定皮质、杏仁核和海马中富含能量的磷酸盐三磷酸腺苷（ATP）和磷酸肌酸（PCr）及其代谢产物二磷酸腺苷（ADP）、一磷酸腺苷（AMP）和肌酸（Cr）的水平。在癫痫活动开始后1小时内，ATP（34 - 60%）和PCr（25 - 52%）显著下降。总腺嘌呤核苷酸（TAN = ATP + ADP + AMP）和总肌酸化合物（TCC = PCr + Cr）也降低（TAN 38 - 60%，TCC 25 - 47%）。ATP/AMP比值未见变化。癫痫发作开始后3天，杏仁核和海马中的ATP和PCr恢复显著，但皮质中未恢复。在给予DFP或呋喃丹前30分钟，用PBN（200 mg/kg，腹腔注射，单次剂量）预处理大鼠，可预防诱发的癫痫发作，并部分预防高能磷酸盐的消耗。用天然抗氧化剂维生素E（100 mg/kg，腹腔注射/天，共3天）预处理，可部分预防高能磷酸盐的损失，而不影响癫痫发作。在对照组中，一氧化氮合成产物瓜氨酸在杏仁核中含量最高，其次是海马，在皮质中最低。DFP或呋喃丹诱导的癫痫发作导致皮质中瓜氨酸水平升高7至8倍，杏仁核和海马中升高3至4倍。这些结果表明SE、兴奋性毒性和能量代谢之间存在密切关系。DFP和呋喃丹在大脑癫痫相关区域引发过量一氧化氮（NO）生成的发现支持了氧化应激的参与。
