延龄草总皂苷通过抑制Keap-1/Nrf2/HO-1、Nrf2/SLC7A11/GPX4通路介导的铁死亡减轻脑缺血/再灌注损伤

Total saponins from Trillium tschonoskii maxim alleviates cerebral ischemia-reperfusion injury by inhibiting ferroptosis through Keap-1/Nrf2/HO-1 and Nrf2/SLC7A11/GPX4 pathways

目的观察延龄草总皂苷(total saponins from Trillium tschonoskii maxim,TST)对大鼠脑缺血/再灌注损伤(cerebral ischemia-reperfusion injury,CIRI)的神经保护作用,并探讨铁死亡相关机制。方法建立CIRI模型后,将雄性SD大鼠分为TST(0.1 g·kg^(-1))组、盐酸多奈哌齐(0.45 mg·kg^(-1))组、模型组以及假手术组。通过Morris水迷宫实验评估大鼠的学习记忆能力,利用Zea-Longa法评估神经功能变化,同时,使用TTC染色观察脑梗死面积,利用HE和Nissl染色检查脑组织的病理变化;为了进一步阐明其作用机制,我们利用透射电子显微镜观察线粒体结构的变化,并测定GSH-PX、SOD、MDA的含量。最后,通过免疫组化、免疫荧光法检测GPX4、Nrf2蛋白的表达。并采用Western blot检测大鼠Keap1/Nrf2/HO-1、Nrf2/SLC7A11/GPX4通路蛋白的表达。结果与假手术组大鼠相比,模型组表现出学习记忆能力下降,脑梗死面积明显增大,神经功能评分较高(P<0.01),神经元排列松散紊乱,尼氏小体减少。同时,线粒体呈现铁死亡状态。铁死亡相关:SOD、GSH-PX活力降低(P<0.01),MDA升高(P<0.01)。GPX4、Nrf2阳性细胞的表达明显减少,GPX4荧光强度降低。此外,海马的Keap1、Nrf2、HO-1、SLC7A11、GPX4的蛋白表达降低(P<0.05,P<0.01)。给予TST后得到改善。结论TST具有神经保护作用,提升了学习记忆能力,降低了氧化应激水平,其机制可能与抑制Keap-1/Nrf2/HO-1、Nrf2/SLC7A11/GPX4通路介导的铁死亡有关。

Aim To examine the neuroprotective impacts of total saponins from Trillium tschonoskii maxim(TST)on cerebral ischemia-reperfusion injury(CIRI)in rats and delve into the mechanisms of ferroptosis.Methods The CIRI model was prepared by dividing male SD rats into the model group,TST(0.1 g·kg^(-1))group,Donepezil hydrochloride(0.45 mg·kg^(-1))group,and sham group.The cognitive functions of rats in each group were assessed through the Morris water maze test,the changes in neurological function were evaluated using the Zea-Longa method,the infarct area was observed via TTC staining,and the pathological alterations in brain tissue were analysed using HE and Nissl staining.To further investigate the underlying mechanism,the mitochondrial structural changes were examined using transmission electron microscopy,and the levels of GSH-PX,MDA,and SOD were analyzed.Additionally,the expressions of GPX4 and Nrf2 proteins were evaluated through immunohistochemistry and immunofluorescence.Furthermore,the protein levels of Keap1/Nrf2/HO-1 and Nrf2/SLC7A11/GPX4 pathways in rats were examined using Western blotting.Results The rats in the model group displayed diminished learning and memory capabilities in comparison to those in the sham group,as well as a significantly increased cerebral infarction area and higher neurological function scores(P<0.01),significantly increased cerebral infarct area,disordered and loosely arranged neurons,and reduced Nissl bodies.Additionally,mitochondria showed typical signs of ferroptosis.Changes related to ferroptosis included decreased activities of SOD and GSH-PX(P<0.01)and increased MDA levels(P<0.01).The expression of GPX4 and Nrf2-positive cells was significantly reduced,along with decreased fluorescence intensity of GPX4.Furthermore,the protein expression of Keap1,Nrf2,HO-1,GPX4,SLC7A11 in the hippocampus decreased(P<0.05,P<0.01).Following the administration of TST,these effects showed improvement.Conclusions TST has neuroprotective effects,enhancing learning and memory abilities while reducing oxidative stress levels.The mechanism may involve the inhibition of ferroptosis through the Keap-1/Nrf2/HO-1 and Nrf2/SLC7A11/GPX4 pathways.