Molecular Mechanism Research of Wenshen Yanggan Decoction on Dopaminergic Neuron Injury in MPTP-Induced Parkinson's Disease

  OBJECTIVE  To explore the potential mechanism of Wenshen Yanggan Decoction on protecting dopaminergic neurons and delaying the process of Parkinson's disease (PD).

  METHODS  Fifty mice were randomly divided into 5 groups (n=10): control group, model group, Wenshen Yanggan Decoction high dose group, Wenshen Yanggan Decoction low dose group and amantadine group. Except for the control group, mice were injected intraperitoneally with 30 mg · kg^-1 of 1-methyl-4-phenyl-1, 2, 3, 6-tetrahydropyridine (MPTP) twice a week for 4 consecutive weeks to establish a Parkinson's disease (PD) mouse model. The mice were administrated with Wenshen Yanggan Decoction by gavage once a day for 3 weeks. The behavioral effects of mice were observed. Immunohistochemistry and Nissl staining were used to detect the number of DA neurons. The contents of DA, 3, 4-dihydroxyphenylacetic acid (DOPAC) and homovanillic acid (HVA) in pathological tissues were measured by HPLC. Colorimetric method was used to determine the activities of ATPase and mitochondrial respiratory chain ComplexⅠ in the substantia nigra. The protein expression levels of PINK1, Parkin, VDAC1, LC3Ⅱ/Ⅰ, and P62 were detected by Western blot.

  RESULTS  The behavioral tests showed that compared with the model group, Wenshen Yanggan Decoction significantly improved the muscle strength and exercise balance of mice (P < 0.01), and prolonged the duration of mice on the roller (P < 0.01). The Results of the immunohistochemistry demonstrated that a large number of TH immunoreactive cells and obvious cell protrusions were observed in Wenshen Yanggan Decoction high dose group, which was consistent with the Results of the Nissl staining assay. In addition, Wenshen Yanggan Decoction significantly increased the levels of DA and HVA (P < 0.05, P < 0.01) in the striatum. Furthermore, treatment with the high dose Wenshen Yanggan Decoction profoundly promoted the activities of ATPase and ComplexⅠ(P < 0.01), up-regulated the protein levels of PINK1 (P < 0.05), Parkin (P < 0.01) and LC3Ⅱ/Ⅰ (P < 0.01), and inhibited P62 protein expression (P < 0.01) in MPTP-induced mice.

  CONCLUSION  Wenshen Yanggan Decoction can improve mitochondrial function, and provide neuroprotective effect in PD by activating PINK1/Parkin mediated mitochondrial autophagy pathway.