内源性一氧化碳对反复热性惊厥脑损伤大鼠内质网应激PERK信号通路的调控作用

Regulating effect of endogenous carbon monoxide on brain damage induced by recurrent febrile seizures through GRP78-PERK-aLF2a-CHOP signal pathway

目的观察内源性血红素加氧酶1（HO-1）／一氧化碳（CO）系统对反复热性惊厥（FS）脑损伤大鼠内质网应激PERK信号通路的调控作用。方法21日龄雄性SD大鼠48只，随机分为正常对照组、Fs组、Fs＋锌原卟啉（ZnPP—IX）组和Fs＋血红素（Hemin）组，每组12只；采用反复热水浴法诱导大鼠惊厥，隔日1次，共诱导10次；记录各组大鼠惊厥潜伏期、惊厥强度及惊厥持续时间；双分光光度计法间接测定皮质CO水平；原位缺口末端标记法（TUNEL）检测皮质神经元凋亡情况；免疫组织化学法测定各组大鼠皮质中HO—1、GRP78、P—PERK、P-eIF2ct及CHOP蛋白表达。结果Fs组、Fs＋ZnPP-Ⅸ组和Fs＋Hemin组大鼠惊厥潜伏期、强度及持续时间比较差异均无统计学意义（P均〉0．05）；FS组大鼠大脑皮质CO水平较正常对照组增高（P〈0．05），Fs4-ZnPP—IX组较Fs组皮质CO水平明显降低，Fs＋Hemin组较Fs组皮质CO水平明显升高，差异均有统计学意义（P均〈0．05）。FS组大鼠皮质神经元凋亡细胞数较正常对照组明显增多，Fs＋ZnPP-Ⅸ组大鼠皮质神经元凋亡较Fs组进一步增多，Fs＋Hemin组神经元凋亡较FS组减少。免疫组织化学显示各组均有HO-1、GRP78、p-PERK、p-elF20t及CHOP蛋白表达，与Fs组比较，Fs＋znPP-Ⅸ组HO-1、GRP78蛋白表达减少，P—PERK、P—elF2ct及CHOP蛋白表达增高，而Fs4-Hemin组HO-1、GRP78表达增高，P—PERK、P—eIF2ct及CHOP蛋白表达减少。结论低浓度增加HO-1／CO的表达够减轻反复Fs导致的脑损伤；HO-1／CO可能通过内质网GRP78-PERK-elF20t—CHOP／GADD153通路发挥对反复Fs脑损伤大鼠的保护作用。

Objective To observe the effect of endogenous heme oxygenase 1 （HO-1）/carbon monoxide（CO） system on brain damage induced by recurrent febrile seizures （ FS ） through GRP78-PERK-eIF2c^-CHOP signal path- way. Methods Forty-eight SD male rats of 21 days were randomly divided into 4 groups ： control group, FS group, FS with ZnPP-IX （ FS ＋ ZnPP-IX） group,and FS with Heroin（ FS ＋ Heroin） group, 12 rats in each group. Hyperthermia treatment was carried out 10 times, once every 2 days. For group FS ＋ Hemin, Hemin, a CO donor was administered intraperitoneally 0. 5 hour before each immersion. For group FS ＋ ZnPP-IX, ZnPP-IX, an inhibitor of HO-1 were precondi- tioned intraperitoneally 0. 5 hour before each immersion. The seizure latency, seizure intensity and seizure duration of FS rats were reeorded. The content of CO in cortex was measured by using dual wavelength spectropotometey. Neuron apop- tosis was deteeted by using TUNEL. The expressions of GRP78 ,p-PERK,p-eIF2a and CHOP in eortex were measured by using immunohistoehemistry. Results No difference in the seizure latency,seizure intensity and seizure duration in the rats FS ＋ ZnPP- IX group or the FS ＋ Heroin were recorded, compared with those in the FS group （ all P 〉 0.05 ）. The content of CO in cortex increased after recurrent FS（ P 〈0. 05 ）. The generation of CO further up-regulated the expres- sions in FS ＋ Heroin group ,while it decreased the expressions in FS ＋ ZnPP-IX group（ all P 〈 0.05 ）. Neuronal apopto- sis was evident in the FS group. Hemin reduced neuronal apoptosis, up-regulated the expression of GRP78, down-regula- ted the contents of CHOP, p-PERK and p-eIF2oL ;ZnPP-IX further induced neuronal apoptosis, and down-regulated the expression of GRP78 ;it aslo up-regulated the expression of CHOP, p-PERK and p-eIF2a. Conclusions Endogenous HO-1/CO system protects the rats from brain damage induced by recurrent FS through endoplasmic GRP78-PERK- eIF2ct-CHOP/GADD153 signal pathway.