大鼠癫痫持续状态后肌醇酶1α介导的内质网应激相关凋亡分子在海马中的表达

Expressions of inositol requiring enzyme 1a mediated endoplasmic reticulum stress-associated molecules in the hippocampus of rats following status epilepsy

目的探讨肌醇酶10／．（inositol requiring enzyme1d，IRE1a）介导的内质网应激相关凋亡分子在大鼠癫痫持续状态（SE）后海马神经元损伤中的作用。方法Wistar大鼠按随机数字表随机分为对照组、SE组，SE组根据不同时间点又分为3、6、12、24、48h组。免疫荧光法观察葡萄糖调节蛋白78（glucose—regulating protein 78kd，GRP78）及磷酸化-IRE1a（p-IRE1a）在各组大鼠海马CA3区中的表达；蛋白质印迹检测磷酸化c-JunN端激酶（p-JNK）、半胱氨酸天冬氨酸蛋白酶12（caspasel2）的表达变化；荧光TUNEL观察各组大鼠海马CA3区神经元凋亡变化。结果免疫荧光结果显示，对照组仅见少量GRP78、p-IRE1a阳性神经元（分别为6．90％-t-O．96％，4．60％±1．12％），SE各亚组GRP78、p-IRE1a阳性神经元均增多，SE后12h达高峰（GRP78：87．45％±3．63％，F=356．82，P〈0．05；p-IREl仅：86．90％±3．82％，F=300．80，P〈0．05）；蛋白质印迹结果显示，与对照组相比，p-JNK、caspasel2在SE各亚组表达均增多，SE后12h达高峰；同时TUNEL染色在SE各亚组均能检测到海马神经元凋亡，以SE后12h凋亡最严重，与p-IREld、p-JNK、caspasel2表达变化一致。结论大鼠SE后诱发了内质网应激，表现为内质网应激标志分子GRP78表达增加；IREl仅可能通过磷酸化JNK和活化easpasel2参与了SE后神经元凋亡损伤。

Objective To explore the role of inositol requiring enzyme 1 a （IRE1a） mediated endop1asmic reticulum stress associated apoptotic molecules in hippocampal neuronal injury in rats with status epilepsy following lithium-pilocarpine. Methods All 96 Wistar rats were randomly divided into control group and status epilepsy （SE） group. The SE group was further divided into 5 subgroups （3, 6, 12, 24, 48 h ） according to different time points. Immunofluorescence was used to observe the expressions of endop1asmic reticulum stress （ERS） markers glucose-regu1ating protein 78 kd （ GRP78 ） and phosphoIRE1a （active form of endop1asmic reticulum resident protein IRE1a） at the CA3 area of rats in each group. Then, the expressions of IRE1a mediated downstream apoptotic markers phospho-c-JunNterminalkinase （JNK） and caspasel2 were detected. Finally, TUNEL assay was used to observe neuronal apoptosis of hippocampal CA3 area at different time points after SE in rats. Results Immunofluorescence showed that GRP78 and phospho-IRE1a positive neurons were significantly increased in the SE subgroups compared with control group （ 6. 90% ± 0. 96%, 4. 60% ± 1.12%, respectively） and 12 h subgroup reached the peak （GRP78： 87.45% ± 3.63%, F = 356. 82, P 〈 0.05; phospho-IRE1a： 86.90% ± 3.82% , F = 300. 80, P 〈 0. 05）. Immunohistochemistry and Western blot demonstrated that the levels of phospho-JNK and caspasel2 in the SE subgroups were significantly higher than that in the control group which reached the peak at 12 h after SE. The changes were in accord with phospho-IREloL. Simultaneously, hippocampal neuronal apoptosis was detected in each SE subgroup and was most severe at 12 h after SE, which showed similar changes to the expressions of phospho-IRElc~, phospho-JNK and caspasel2. Conclusions ERS was induced in rats following SE evidenced by increasing the expression of GRP78. IRElct may promote hippocampal neuron apoptosis in rats following SE through activating JNK and caspasel2.