热休克蛋白70对氧惊厥的预防作用及机制研究

Hyperbaric oxygen-induced seizures usually occur in diving and hyperbaric oxygen therapy. During the seizures people may have full body tonic contraction, paroxysmal spasms, or loss of consciousness, which had serious pernicious influence on safety. So effective prevention of hyperbaric oxygen-induced seizures and safe application of oxygen are of great significance to the military and civilian diving as well as clinical hyperbaric oxygen therapy. Our previous studies found that nitric oxide synthase (NOS) and nitric oxide (NO) played an important role in the hyperbaric oxygen-induced seizures, and a single oral administration of a strong heat shock protein 70 (HSP70) inducer geranylgeranylacetone (GGA) effectively prevented the seizures. The present study aims to further explore the underlying mechanism of this effect of HSP70, from animal, cellular and molecular level, which probably regulate NOS expression and NO production related signaling pathways by inhibiting the nuclear translocation of NF-κB. New measures and mechanisms to prevent hyperbaric oxygen-induced seizure are supposed to be explored and a new strategy for the prevention of hyperbaric oxygen-induced seizure will be developed.

氧惊厥多发生在潜水活动与高压氧治疗中，发作时人员可出现全身强直性收缩以及阵发性痉挛并意识丧失，严重影响人员安全。有效预防氧惊厥，最大限度地安全用氧，对军事和民用潜水作业以及临床高压氧治疗都具有重要意义。我们的前期研究发现，一氧化氮合酶（NOS）和一氧化氮（NO）在氧惊厥中起着重要作用，而单次口服给予热休克蛋白70（HSP70）诱导剂替普瑞酮可有效预防氧惊厥。本研究拟进一步揭示HSP70预防氧惊厥的内在机制，探索HSP70通过抑制NF-κB的核转位调节NOS表达和NO生成相关信号通路，从动物及细胞分子水平探索预防氧惊厥的新的措施及机制，为预防氧惊厥提供新的策略。

研究背景：中枢神经系统氧中毒（CNS-OT）简称氧惊厥，又名惊厥型氧中毒，是潜水活动、HBO治疗及高气压环境作业人员需要面对的重要医学问题，关键在于预防。海马组织是CNS-OT发作的核心区域。我们前期研究发现，大鼠海马组织HSP70高表达可明显延长大鼠CNS-OT发作的的潜伏期，并减轻其首次发作的惊厥程度。本项目旨在阐明HSP70延缓对抗CNS-OT发作的效应及其机制。.研究内容：⑴ 观察了通过替普瑞酮灌胃诱导大鼠海马区HSP70的高表达；⑵观察了HSP70延长CNS-OT发作潜伏期对抗其发作的效应；⑶ 观察了各型NOS及nF-κB在SD大鼠CNS-OT发作中所发挥的不同作用；⑷观察了HSP70通过HSP70—nF-κB—NOS—NO信号传导系统延缓对抗CNS-OT发作的作用机制。.研究结果：⑴在替普瑞酮灌胃24h后大鼠海马区HSP70显著升高，在暴露48h后达最高值。⑵HSP70高表达后可明显延长大鼠CNS-OT潜伏期和首次放电潜伏期，抑制脑血流量的增多，并且其效应可以被HSP70抑制剂槲皮素所抑制。⑶nNOS、iNOS及nF-κB在SD大鼠CNS-OT发挥着重要作用，而eNOS在其中发挥的作用不大。⑷HSP70通过HSP70—NF-κB—NOS—NO信号传导系统延缓对抗CNS-OT发作。.结论和意义：HSP70可明显抑制大鼠海马区及体外培养海马神经元的nF-κB活化入核，降低了iNOS、nNOS的含量，NO生成量也明显减少，相应降低了大鼠海马区域的脑血流量，延缓了CNS-OT的发作。