Oxidative and endoplasmic reticulum stress in absence epilepsy

为了表征缺失癫痫相关的内质网（ER）应激诱导的细胞损伤在嗜睡小鼠（Ih/Ih）中增加，一个缺失癫痫的遗传模型，参与内质网应激诱导的大脑细胞死亡的负责通路在嗜睡小鼠和对照组之间进行了比较。昏睡小鼠丘脑湿重明显低于对照组。丘脑已被证明在癫痫缺失中起着重要作用。嗜睡小鼠丘脑葡萄糖调节蛋白（GRP）78、ER伴侣蛋白水平及c-jun- n-末端激酶（JNK）、磷酸化JNK/JNK活性均高于对照组。这些数据表明，在缺失性癫痫模型中，内质网应激在丘脑中被诱导。为了阐明细胞损伤通路的潜在机制，研究了内质网应激（tunicamyine； TM）-和氧化应激（H_2O_2和4-羟基-2-壬烯醛；HNE）-诱导小鼠海马细胞系HT22细胞的细胞损伤通路。TM、H_2O_2和HNE处理使细胞活力呈时间和浓度依赖性降低。暴露于TM后，GADD153/C/EBP同源蛋白（CHOP）被显著诱导。相比之下，内质网应激特异性caspase-12的表达不受TM的影响。在H_2O_2处理的细胞中，核区DJ-1和NF-kB亚基的免疫反应活性显著升高。H2O2还诱导细胞内Ca^<2+>浓度升高，而Ca^<2+>通道抑制剂氯化钴抑制了H2O2诱导的细胞死亡。在hne处理的细胞中，没有观察到这些现象；HNE暴露后可形成HNE加合物蛋白，H_2O_2则不形成。需要进一步的实验来确定缺席癫痫时内质网和氧化应激相关通路的细节。

In order to characterize absence epilepsy-associated increases in endoplasmic reticulum (ER) stress-induced celluar damege in lethargic(Ih/Ih)mice, a genetic model of absence epilepsy, responsible pathways involved in the ER stress-induced cell death in the brain were compared between lethargic and control mice. The wet weight of the thalamus in lethargic mouse was lower than that in control mouse. The thalamus has been shown to play an important role in the absence epilepsy. The level of glucose regulated protein (GRP)78, ER chaperons, and activity of c-jun-N-terminal kinase (JNK), phospho-JNK/JNK in the thalamus of lethargic mouse higher than that of control mouse. These data suggested that ER stress was induced in the thalamus in a model of absence epilepsy.In order to elucidate underlying mechanism of cell injury pathways, ER stress (tunicamycine ; TM)- and oxidative stress (H_2O_2 and 4-hydroxy-2-nonenal ; HNE)-induced cell injury pathways were investigated in HT22 cells, a mouse hippocampal cell line. Treatment with TM, H_2O_2 and HNE decreasedthecell viability in a time-and concentration-dependent manner. GADD153/C/EBP homologous protein (CHOP) was significantly induced after exposure to TM. In contrast, expression of caspase-12, ER stress-specific caspase, was not affected by TM. In the cells treated with H_2O_2, significant increases in the immunoreactivities of DJ-1 and nuclear factor-kB (NF-kB) subunits were observed in the nuclear fraction. H2O2 also induced an increase in the intracellular concentration of Ca^<2+> and cobalt chloride, a Ca^<2+> channel inhibitor, suppressed the H_2O_2-induced cell death. In HNE-treated cells, none of these phenomena were observed ; however, HNE adduct proteins were formed after exposure to HNE, but not to H_2O_2.Further experiments are needed to ascertain whether the details of responsible pathways involved in the ER and oxidative stress in absence epilepsy.