Study on Electroacupuncture Improving Parkinson’s Disease Symptoms by Regulating Autophagy

Academic Background

Parkinson’s disease (PD) is the second most common neurodegenerative disease worldwide, primarily characterized by the gradual loss of dopamine (DA) neurons in the substantia nigra of the midbrain and the abnormal accumulation of α-synuclein, leading to motor impairments such as bradykinesia, rigidity, resting tremor, and gait disturbances. Current treatments for PD mainly rely on dopamine replacement therapy, particularly the use of levodopa. However, levodopa has limitations in the advanced stages of the disease, including a narrow therapeutic window and significant side effects. Therefore, finding safe and effective alternative therapies has become a research focus.

Autophagy is a cellular process responsible for degrading abnormal, aggregated, or misfolded proteins and is essential for maintaining neuronal homeostasis. Studies have shown impaired autophagy function in both PD patients and animal models, and restoring autophagy may have significant neuroprotective implications. Nuclear factor erythroid-2-related factor 2 (NRF2) is a key regulator of autophagy-related genes and can maintain cellular homeostasis by activating the expression of autophagy-related proteins. Electroacupuncture (EA), as an alternative therapy with minimal side effects and notable efficacy, has been widely applied in clinical practice for PD treatment. However, whether EA exerts neuroprotective effects by regulating autophagy through the NRF2 signaling pathway remains unclear.

Source of the Paper

This paper was co-authored by Jiping Zhang, Zhiyi Fu, and others, with the research team primarily from the School of Traditional Chinese Medicine at Southern Medical University, the Department of Ultrasonic Diagnosis at the General Hospital of Southern Theater Command of the PLA, and the Department of Neurosurgery at Beijing Tsinghua Changgung Hospital, among other institutions. The paper was first published on January 2, 2025, in the Journal of Neurophysiology, with the DOI 10.1152/jn.00497.2024.

Research Process

1. Animal Model Establishment and Grouping

The study used 8-10-week-old male C57BL/6 wild-type (WT) mice and NRF2 knockout (KO) mice. The PD model was established by intraperitoneal injection of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) for seven consecutive days. After MPTP injection, WT mice were randomly divided into three groups: MPTP group, MPTP + EA group, and MPTP + Madopar (MA) group; NRF2 KO mice were divided into MPTP group and MPTP + EA group.

2. Electroacupuncture Intervention

EA intervention was applied at the Baihui (GV20) and Taichong (LR3) acupoints. The stimulation frequency was 2 Hz, with sessions lasting 20 minutes daily for 14 days. Mice in the EA group remained awake during treatment, while the MA group received levodopa treatment.

3. Behavioral Analysis

Motor function was assessed through the rotarod test and pole test. In the rotarod test, the time mice remained on an accelerating rotating rod was recorded, while in the pole test, the time taken for mice to climb from the top to the bottom of the pole was measured.

4. Histological Analysis

After behavioral testing, mice were anesthetized and perfused, and brain tissues were collected for immunohistochemistry (IHC) and immunofluorescence (IF) staining to detect the expression levels of tyrosine hydroxylase (TH) and α-synuclein. Additionally, transmission electron microscopy (TEM) was used to observe changes in the number of autophagosomes and lysosomes in the substantia nigra.

5. Molecular Mechanism Study

The expression levels of autophagy-related proteins (ATG7, LC3II, p62) and NRF2 signaling pathway-related molecules (NRF2, KEAP1) were detected using Western blot and reverse transcription quantitative polymerase chain reaction (RT-qPCR).

Key Findings

1. EA Improves Motor Function

Both EA and levodopa treatments significantly improved motor dysfunction in MPTP-induced mice. In the rotarod test and pole test, the motor performance of mice in the EA and MA groups was significantly better than that of the MPTP group.

2. EA Protects Dopamine Neurons

The number of TH-positive neurons in the substantia nigra was significantly reduced in the MPTP group, while both EA and levodopa treatments significantly reduced neuronal loss. Additionally, EA significantly decreased α-synuclein expression levels.

3. EA Restores Autophagy Function

The expression of autophagy-related proteins ATG7 and LC3II was significantly reduced, and p62 levels were significantly increased in the MPTP group, indicating impaired autophagy. Both EA and levodopa treatments significantly upregulated the expression of ATG7 and LC3II and reduced p62 levels, suggesting restored autophagy function.

4. EA Activates the NRF2 Signaling Pathway

EA significantly upregulated the expression levels of total NRF2 and nuclear NRF2 while reducing KEAP1 expression. In NRF2 KO mice, the regulatory effects of EA on autophagy-related proteins were absent, and no neuroprotective effects were observed.

Conclusion

This study demonstrated that EA ameliorates motor dysfunction and dopamine neuron loss in MPTP-induced PD mice by regulating autophagy function through the activation of the NRF2 signaling pathway. This finding not only provides new insights into the mechanisms of EA treatment for PD but also offers potential new directions for PD treatment strategies.

Research Highlights

1. Neuroprotective Effects of EA: EA significantly improved motor dysfunction and reduced dopamine neuron loss in MPTP-induced mice.
   
2. Restoration of Autophagy Function: EA restored autophagy function by upregulating ATG7 and LC3II expression while reducing p62 levels.
   
3. Key Role of the NRF2 Signaling Pathway: EA’s neuroprotective and autophagy-regulating effects depend on the activation of the NRF2 signaling pathway.
   
4. Innovative Experimental Design: The study combined behavioral, histological, and molecular biological methods to systematically validate the efficacy and mechanisms of EA.
   

Scientific and Practical Value

This study not only deepens the understanding of the mechanisms of EA treatment for PD but also provides a theoretical basis for developing PD treatment strategies targeting the NRF2 signaling pathway. In the future, EA, as an alternative therapy with minimal side effects and significant efficacy, is expected to be more widely applied in the clinical treatment of PD.