一氧化碳对热性惊厥大鼠海马一氧化氮合酶/一氧化氮体系的影响

Effect of carbon monoxide on nitric oxide synthase/nitric oxide system in hippocampus of rats with febrile seizures

目的反复热性惊厥(FS)后血红素氧合酶(HO)/一氧化碳(CO)系统和一氧化氮合酶(nNOS)/一氧化氮(NO)系统上调,但二者相互关系不清。本研究观察HO抑制剂锌原卟啉Ⅸ(ZnPPⅨ)对FS大鼠海马神经元型NOS(nNOS)mRNA和蛋白表达及NO含量的影响,以探讨CO对NOS/NO体系的调节作用。方法采用热水浴诱导大鼠FS,隔日诱导1次,共诱导10次。发育期大鼠随机分为3组:对照组,FS组,FS+ZnPPⅨ组(均n=16)。分光光度计间接测定血浆CO和NO含量;核酸原位杂交法检测海马nNOSmRNA表达;Westernblot方法检测海马nNOS蛋白含量。结果反复FS后海马nNOSmRNA和蛋白表达增高。用ZnPPⅨ进行干预后,血浆CO含量下降,海马nNOSmRNA和蛋白表达及血浆NO含量呈现一致性的显著。结论反复FS时,外源性给予HO抑制剂ZnPPⅨ可可抑制HO/CO系统,降低血浆CO,增加神经元NOS的基因表达及NO含量,提示CO可能下调NOS/NO系统活性。

Objective Heme oxygenase（ HO）/carbon monoxide（CO） system and nitric oxide synthase（NOS）/nitric oxide（NO） system are up-regulated after recurrent febrile seizures （FS）. The relationship between HO/CO and NOS/NO systems is unknown. This study examined the effect of the HO inhibitor zinc protoporphyrin Ⅸ （ ZnPP-Ⅸ ） on the expression of neuronal NOS （nNOS） mRNA and protein and also the plasma NO content in rats with recurrent FS. The goal was to study the effect of CO on the NOS/NO system. Methods Forty-eight developing rats were randomly assigned into three groups： Control group, FS group, and ZnPP-Ⅸ-treated FS group （ n = 16 each）. FS were induced in rats by exposure to warm water bath, once every 2 days, 10 times in all. Plasma levels of NO and CO were detected by spectrophotometry. The expression of nNOS mRNA was detected in hippocampal neurons by in situ hybridization, nNOS protein expression in hippocampal neurons was examined by Western blot analysis. Results Recurrent FS induced an increased expression of nNOS mRNA and protein in hippocampal neurons. ZnPP-Ⅸ treatment decreased the concentrations of CO in plasma and increased the expression of nNOS mRNA and protein in hippocampal neurons and the NO content in plasma. Conclusions Exogenously administering the HO inhibitor ZnPP-Ⅸ may increase the nNOS gene expression and NO production in recurrent FS, suggesting that CO might down-regulate the activity of NOS/NO system.