Compound Dihuang Granule (CDG) is widely used in traditional Chinese medicine (TCM) for the treatment of Parkinson’s disease (PD). It has been shown to alleviate PD symptoms. However, the molecular mechanisms of its action have not been established. To establish the molecular mechanisms of CDG against PD, we used TCM network pharmacology methods to predict its molecular targets and signaling pathways, followed by experimental validation. The Core Protein protein interaction (PPI) network of the 150 intersections between CDG and PD-related genes, comprising 23 proteins, including CASP3 (caspase-3), MAPK8 (JNK), FOS (c-Fos), and JUN (c-Jun). KEGG and GO analyses revealed that apoptotic regulation and MAPK signaling pathways were significantly enriched. Since c-Jun and c-Fos are AP-1 subunits, an important downstream JNK effector, we investigated if the JNK/AP-1 pathway influences CDG against apoptosis through the nigrostriatal pathways in PD rat models. Molecular docking analysis found that the top three bioactive compounds exhibiting the highest Degree Centrality following online database and LC-MS analysis had high affinities for JNK. Experimental validation analysis showed that CDG decreased the number of rotating laps and suppressed the levels of phosphorylated c-Jun, c-Fos, and JNK, as well as the number of TUNEL positive cells and the cleaved caspase-3 level in the nigrostriatal pathway. Furthermore, CDG treatment elevated the number of TH neurons, TH expression level, and Bcl-2/Bax protein ratio in a 6-OHDA-induced PD rat. These findings are in tandem with those obtained using SP600125, a specific JNK inhibitor. In conclusion, CDG suppresses the apoptosis of the nigrostriatal pathway and relieves PD symptoms by suppressing the JNK/AP-1 signaling pathway.

Compound Formula Rehmannia has been shown to be clinically effective in treating Parkinson's disease and levodopa-induced dyskinesia; however, the mechanisms remain unclear. In this study, we established a model of Parkinson's disease dyskinesia in rats, and treated these animals with Compound Formula Rehmannia. Compound Formula Rehmannia inhibited the increase in mRNA expression of N-methyl-D-aspartate receptor subunits 1 and 2 and excitatory amino acid neurotransmitter genes, and it inhibited the reduction in expression of γ-aminobutyric acid receptor B1, an inhibitory amino acid neurotransmitter gene, in the corpus striatum. In addition, Compound Formula Rehmannia alleviated dyskinesia symptoms in the Parkinson's disease rats. These experimental findings indicate that Compound Formula Rehmannia alleviates levodopa-induced dyskinesia in Parkinson's disease by modulating neurotransmitter signaling in the corpus striatum.

Parkinson’s disease (PD) is a common degenerative disease of the nervous system that seriously affects the quality of life of the patients. The pathogenesis of PD is not yet fully clear. Previous studies have confirmed that patients with PD exhibit obvious gut microbiota imbalance, while intervention of PD by regulating the gut microbiota has become an important approach to the prevention and treatment of this disease. Traditional Chinese medicine (TCM) has been shown to be safe and effective in treating PD. It has the advantages of affecting multiple targets. Studies have shown TCM can regulate gut microbiota. However, the specific mechanism of action is still unclear. Therefore, this article will mainly discuss the association of the alteration of the gut microbiota and the incidence of PD, the advantages of TCM in treating PD, and the mechanism of regulating gut microbiota by TCM to treat PD. It will clarify the target and mechanism of TCM treating PD by acting gut microbiota and provided a novel methodology for the prevention and treatment of PD.

Background: Parkinson’s disease (PD) is a multifactorial neurodegenerative disorder characterized by progressive loss of dopaminergic (DA) neurons in the substantia nigra pars compacta (SNpc) and the presence of Lewy bodies (LBs) consisting of misfolded α-synuclein protein in the substantia nigra pars compacta (SNpc). Compound Dihuang Granule (CDG), a famous traditional Chinese medicine (TCM) has been clinically used in PD therapy with curative effects. However, the specific functions and the mechanism of action remained unclear. This paper study assesses the preventive and therapeutic effect of CDG on motor deficits and DA neuron loss of PD induced by 6-OHDA and the underlying mechanisms.Methods: PD rat model was induced by unilaterally stereotactic injection of 6-OHDA into the SNpc of midbrain then the motor deficits were evaluated with apomorphine (APO) induced abnormal rotational behaviors. The striatal contents of neurotransmitters were detected by high performance liquid chromatography with electrochemical detection (HPLC-ECD). The number of DA neurons were determined with immunohistochemistry (IHC) staining. Protein expression levels were determined with Western blotting assay. Indicators of oxidative stress were determined with colorimetric method. Apoptotic cells were detected by Transferase-mediated deoxyuridine triphosphate-biotin nick end labeling (TUNEL) assay. The expression of neurotrophic factors was examined with IHC staining.Results: With a 6-week treatment, CDG significantly attenuated the 6-OHDA induced abnormal rotational behaviors and alleviated the loss of DA neurons in the nigrostriatal axis. Consistently, the striatal contents of DA and its metabolites including DOPAC and HVA of PD rats were all significantly increased with CDG treatment. The 6-OHDA induced oxidative stress indicated with decreased superoxide dismutase (SOD), glutathione (GSH), glutathione peroxidase (GSH-Px) and increased malondialdehyde (MDA)was also suppressed by CDG. Moreover, CDG treatment inhibited the 6-OHDA induced cell apoptosis indicated with decreased apoptotic cells in the SNpc and increased protein expression ratio of Bcl-2/Bax in the striatum. The expression levels of neurotrophic factors including nerve growth factor (NGF), brain-derived neurotrophic factor (BDNF) and glial-derived neurotrophic factor (GDNF)in the SNpc of PD rats were also increased by CDG.Conclusion: CDG could ameliorate the 6-OHDA induced brain injuries and motor symptoms mainly by inhibition of the oxidative stress and cell apoptosis in the nigrostriatal axis, and enhancing the expression of neurotrofic factors in the midbrain of rats.