Regulatory Mechanism Of α-Lipoic Acid On Iron Efflux In Parkinson’s Disease Model

Objective: To observe the effect of α-lipoic acid(α-LA)on the expressions of ferroportin1(FP1),iron regulatory protein 1(IRP1)and iron regulatory protein 2(IRP2)in substantia nigra(SN)of Parkinson’s disease(PD)rat models and in the cell model of PD and explore the mechanism by which α-LA regulates iron efflux in PD model.Methods: Animal experiment: 60 healthy male SD rats were randomly divided into sham operation group(15 rats)and model group(45 rats).The model group was established by injecting 6-hydroxydopamine(6-OHDA)into the right striatum of rats by stereotactic technique,and the sham operation group was injected with the same dose of normal saline.After 4 weeks,the successful models(30rats)were screened by rotation experiments and were randomly divided into PD model group(15 rats)and PD treatment group(15 rats).The PD treatment group was intraperitoneally injected with α-LA(50 mg/kg)daily for 2 weeks,PD model group given the same dose of saline.After 14 days of treatment,the left forelimb use rate was tested by cylinder test.The right midbrain substantia nigra was taken in each group,the expression and distribution of tyrosine hydroxylase(TH)was detected by immunohistochemical staining,the number of iron positive cells were detected by Prussian blue staining,and the levels of FP1,IRP1,IRP2 were detected by Western Blot.Cell experiment: PC12 cells were cultured in vitro.The optimum concentration of 6-OHDA and α-LA were screened by MTT method.It was divided into 3 groups:the normal control group,the model group(100μmol/L 6-OHDA),the α-LA intervention group(100μmol/L α-LA +100μmol/L 6-OHDA).The concentrations of malondialdehyde(MDA)and iron were measured by colorimetric method,and the expressions of FP1,IRP1 and IRP2 were examined by Western Blot.Results:Animal experiment:(1)compared with the sham operation group,the left forelimb use rate of PD model group was significantly reduced(P<0.01),the number of THpositive cells in the right SN decreased significantly(P<0.01),the number of iron positive cells increased significantly(P<0.01),the expression of FP1 was significantly reduced(P<0.01),the expression of IRP2 was significantly increased(P<0.01),and the expression of IRP1 had no difference statistical significance(P>0.05).(2)compared with the PD model group,the left forelimb use rate of the PD treatment group was significantly raised(P<0.01),the number of TH positive cells in the right SN was significantly increased(P<0.01),the number of iron positive cells was significantly reduced(P<0.01),the expression of FP1 was significantly increased(P<0.01),the expression of IRP2 was significantly decreased(P<0.01),and the expression of IRP1 had no difference statistical significance(P>0.05).Cell experiment:(1)compared with normal control group,the cell viability of model group was significantly decreased(P<0.01),the concentrations of MDA and iron were significantly increased(P<0.01),the expression of FP1 was significantly decreased(P<0.01),and the expressions of IRP1 and IRP2 were significantly increased(P<0.01).(2)compared with the model group,the cell viability of α-LA intervention group was significantly increased(P<0.01),the concentrations of MDA and iron were significantly reduced(P<0.01),the expression of FP1 was significantly increased(P<0.01),the expression of IRP1 was reduced(P<0.05),and the expression of IRP2 was significantly decreased(P<0.01).Conclusion:(1)In PD model rats,α-LA can reduce the expression of IRP2 in the midbrain SN,pass the IRP2/IRE pathway,increase FP1 level,promote the outflow of iron ions from cells,and reduce iron deposition.(2)In the PD cell models,α-LA can reduce the expressions of IRP1 and IRP2 in the cell,increase the expression of FP1 through IRPs/IRE pathway,promote the outflow of iron ions from cells,and inhibit iron deposition.