罗沙司他调控线粒体分裂与融合减轻热射病小鼠脑损伤

Roxadustat attenuates brain injury in mice with heat stroke by regulating mitochondrial fission and fusion

目的 探究缺氧诱导因子(hypoxia-inducible factor, HIF)脯氨酰羟化酶(prolyl hydroxylase, PHD)抑制剂罗沙司他(FG-4592)对热射病(heat stroke, HS)导致的脑损伤的保护作用及其机制。方法 选取140只6~8周龄的雄性C57BL/6J小鼠,体质量为18~22 g。其中40只按随机数字表法分为热射病(HS)组,罗沙司他低剂量(LD,5 mg/kg)组、中剂量(MD,10 mg/kg)组、高剂量(HD,20 mg/kg)组,每组10只,进行热打击实验,观察各组小鼠24 h生存情况,确定最佳给药剂量。另外100只小鼠按随机数字表法分为正常对照(Control)组、罗沙司他(FG-4592)组、热射病(HS)组、罗沙司他+热射病(FG-4592+HS)组,每组25只,进行热打击实验,建立HS动物模型。采用改良神经功能缺损评分(modified neurological severity score, mNSS)评价神经功能,脑切片HE染色观察病理损伤情况;Fluoro-Jade C染色观察神经元变性;测定脑组织总超氧化物歧化酶(superoxide dismutase, SOD)活性、丙二醛(malondialdehyde, MDA)含量评价氧化应激情况;透射电镜观察线粒体损伤;Western blot检测大脑皮层中Caspase-3、Cleaved Caspase-3、Mfn1、Mfn2、Opa1、Drp1、p-Drp1(Ser616)、Fis1、HIF-1α、HO-1蛋白表达水平。结果 与HS组比较,FG-4592可以显著提高热射病小鼠24 h内的生存率,且MD组生存率最高。与Control组比较,HS组小鼠mNSS评分增加(P<0.05),大脑皮层MDA含量增加(P<0.05),总SOD活性降低(P<0.05),且大脑皮层组织出现显著病理损伤和神经元变性,大脑皮层组织线粒体结构明显损伤,Caspase-3、Cleaved Caspase-3、Fis1、HIF-1α、HO-1蛋白表达和p-Drp1(Ser616)/Drp1比值升高(P<0.05),Mfn1、Mfn2、Opa1蛋白表达降低(P<0.05)。经FG-4592预处理后显著降低HS小鼠的mNSS评分(P<0.05),降低了组织MDA含量(P<0.05),增加了总SOD活性(P<0.05);同时FG-4592预处理改善了大脑皮层组织病理损伤、减轻了神经元变性和线粒体结构损伤,并降低了Caspase-3、Cleaved Caspase-3、Fis1蛋白表达和p-Drp1(Ser616)/Drp1比值(P<0.05),增加了Mfn1、Mfn2、Opa1、HIF-1α、HO-1蛋白表达(P<0.05)。结论 罗沙司他调控线粒体分裂融合平衡,减轻线粒体结构损伤,减少氧化应激和细胞凋亡,减轻热射病脑损伤。

Objective To explore the protective effect and underlying mechanism of roxadustat(FG-4592),hypoxia-inducible factor-α(HIF-α)prolyl hydroxylase inhibitor,on brain injury caused by heat stroke(HS).Methods A total of 140 male C57BL/6J mice(6~8 weeks old,weighing 18~22 g)were subjected,and 40 of them were randomly divided into HS group,and low-,medium-and high-dose roxadustat groups(LD,MD and HD groups,5,10 and 20 mg/kg),with 10 mice in each group.The 24-hour survival rate was observed to determine the optimal dosage of roxadustat after modeling.Additionally,the remaining 100 mice were randomly allocated to normal control(Control)group,roxadustat(FG-4592)group,HS group,and roxadustat+HS(FG-4592+HS)group,with 25 mice in each.Heat shock was inflicted to establish mouse model of HS.Modified neurological severity score(mNSS)was used to assess neurological function.HE staining of brain sections was performed to examine pathological damage,and Fluoro-Jade C staining was applied to observe neuronal degeneration.The activity of total superoxide dismutase(SOD)and content of malondialdehyde(MDA)in brain tissue were measured to assess oxidative stress.Transmission electron microscopy was employed to visualize mitochondrial damage.Western blotting was performed to assess the protein levels of Caspase-3,Cleaved Caspase-3,Mfn1,Mfn2,Opa1,Fis1,HIF-1α,HO-1 and p-Drp1(Ser616)/Drp1 ratio in the cerebral cortex.Results Compared to the HS group,FG-4592 significantly improved the survival rate of HS mice within 24 h,with the MD group showing the highest survival rate.Compared to the Control group,the HS group showed an increase in mNSS score(P<0.05),an elevation in the MDA content in the cerebral cortex(P<0.05),and a decrease in total SOD activity in the cerebral cortex(P<0.05);HE staining revealed pathological damage in the cerebral cortex,and Fluoro-Jade C staining displayed obvious neuronal degeneration in the cerebral cortex;Electron microscopy revealed obvious mitochondrial structural damage in the cerebral cortex tissue;The protein expression of Caspase-3,Cleaved Caspase-3,Fis1,HIF-1α,HO-1 and p-Drp1(Ser616)/Drp1 ratio was increased(P<0.05),while that of Mfn1,Mfn2,and Opa1 was decreased(P<0.05).Pretreatment with FG-4592 significantly reduced the mNSS score in HS mice(P<0.05),decreased MDA content(P<0.05),and enhanced total SOD activity(P<0.05).Additionally,FG-4592 pretreatment improved pathological damage in the cerebral cortex,reduced neuronal degeneration,and mitigated mitochondrial structural damage.Furthermore,it decreased the protein levels of Caspase-3,Cleaved Caspase-3,Fis1 and p-Drp1(Ser616)/Drp1 ratio(P<0.05),while increased the levels of Mfn1,Mfn2,Opa1,HIF-1α,and HO-1(P<0.05).Conclusion Roxadustat regulates the balance between mitochondrial fission and fusion,reduces mitochondrial structural damage,oxidative stress and apoptosis,and alleviates heat stroke-induced brain injury.