Lipoic Acid Inhibits Caspase-independentapoptosis Mediated By AIF And Protected6-hydroxydopamine Neurotoxicity In Parkinson's Disease

Objective: To investigate whether Lipoic acid(LA)can protect paminergic neurons by inhibiting apoptosis inducing factor(AIF)-mediated Caspase-independent apoptosis pathway.To provide experimental data for clinical treatment for PD.Methods:(1).The PD cell model was established by 6--hydroxy dopamine(6-OHDA)induced PC12 cell injury,and LA intervention was given.The effect of LA on cell viability of PD cell model detected by CCK-8 method.The effects of LA on mitochondrial membrane potential,reactive oxygen and apoptosis in PD cell model were detected by flow cytometry.The effect of LA on TH protein level in PD cell model was detected by Western blot.(2).Healthy male Sprague-Dawley rats were randomly divided into 6-OHDA group(n = 40)and sham-operated group(n = 15).6-OHDA was injected into the right striatum of 6-OHDA group SD rats and injected in the sham operation group.An equal volume of saline was used as a control.At the fourth week after operation,a successf?L rat model of PD was selected by Apomorphine(APO)rotation test(rotating speed to the contralateral side > 2 r/min);randomly divided PD rats were randomly divided into two groups.PD model group and LA intervention group;from the fifth week after operation,the LA intervention group was given lipoic acid(50 mg/kg/d)for 14 days.The behavioral changes in PD model rats were detected by rotating experiment and cylinder experiment,Nuen and th immunohistochemical staining were used to detect the effects of LA on neurons and da energy neurons in the substantia nigra of rats damaged by 6-OHDA.(3).In vivo/in vitro PD models,the effect of LA on the AIF expression in mitochondria and nucleus of PD cell model was detected by Western blot,and the effect of LA on the AIF translaocation in PD cell model was observed by laser confocal microscope.Res?Lts:(1).In vitro,the res?Lts showed that the cell viability of PC12 cells was decreased to 65.28 ± 4.13% after treated with 75 ?mol/L 6-OHDA for 18 h,while it was co-c?Ltured with 75 ?mol/L 6-OHDA after pretreated with 10 ?mol/L LA.h,the cell viability of PC12 cells increased to 80.00 ± 5.41%.Compared with the control groups,After treatment of 6-OHDA,the activity of reactive oxygen species in PC12 cells was significantly increased(P< 0.05),the mitochondrial membrane potential was significantly decreased(P< 0.05),and the apoptosis rate was significantly increased(P< 0.05).P< 0.05),TH expression was significantly reduced(P< 0.05).Compared with 6-OHDA groups,the mitochondrial membrane potential increased significantly in LA treatment group(P< 0.05),the active oxygen content decreased significantly(P< 0.05),and the apoptosis rate was significantly decreased(P< 0.05).Western blot res?Lts showed that the expression of th in LA treatment group increased significantly(P< 0.05)compared with PD model group.(2).In vivo,the res?Lts showed that compared with the control group,the PD model group and the LA intervention group significantly increased the contralateral rotation circle in the APO-induced rotation test(P< 0.05),and the frequency of left forelimb use decreased significantly in the barrel test.(P< 0.05).The number of NueN and TH positive cells in the lesioned substantia nigra decreased significantly(P< 0.05).Compared with the PD model group,LA intervention group significantly decreased the number of contralateral rotations in the rotation experiment(P < 0.05),and the frequency of left forelimb use increased significantly in the cylinder experiment(P< 0.05).The number of NueN and TH positive cells in the substantia nigra was significantly higher(P< 0.05).(3).In vivo/in vitro PD models,the res?Lts showed that compared with the control groups,the expression of AIF in mitochondria was significantly decreased,while the amount of AIF in the nucleus decreased significantly in PC12 cells or rat substantia nigra neurons induced by 6-OHDA(P< 0.05);and colocalization of AIF with nuclei was observed.Compared with PD model group,after LA intervention,the expression of AIF in mitochondria was significantly increased(P< 0.05),while the expression of AIF in the nucleus was significantly decreased(P< 0.05).Conclusion: The Caspase-independent apoptotic pathway mediated by AIF is involved in the loss of dopaminergic neurons in the substantia nigra of PD model.To some extent,the pathophysiology and behavior of PD model were relieved by Lipoic acid,Lipoic acid can protect dopaminergic neurons by inhibiting the Caspase-dePendent apoptotic pathway mediated by AIF in the substantia nigra region.