ABSTRACT
ObjectiveTo investigate the protective effect and mechanism of Achyranthis Bidentatae Radix-Paeoniae Radix Alba on dopaminergic neurons in Parkinson's disease mouse model with the syndrome of ascendant hyperactivity of liver Yang. MethodThe C57BL/6 mice were randomly assigned into normal group， a model group， low-， medium， and high-dose （3.25， 6.5， 13 g·kg-1） Achyranthis Bidentatae Radix-Paeoniae Radix Alba groups， and a selegiline group （0.01 g·kg-1）. The mouse model of Parkinson's disease with the syndrome of ascendant hyperactivity of liver yang was established by intragastric administration of Fuzitang combined with intraperitoneal injection of 1-methyl-4-phenyl-1，2，3，6-tetrahydropyridine （MPTP）. The behavioral changes were evaluated by rotarod test and pole test. The protein levels of Ras homolog gene family member A （RhoA）， Rho-associated coiled-coil containing protein kinase 2 （ROCK2）， myosin light chain 1 （MLC1）， and α-synuclein in the substantia nigra were determined by Western blot. Real-time fluorescence quantitative PCR （Real-time PCR） was employed to determine the mRNA levels of RhoA， ROCK2， and MLC1 in the substantia nigra. Enzyme-linked immunosorbent assay （ELISA） was used to measure the levels of tumor necrosis factor-α （TNF-α） and interleukin-1β （IL-1β）. The ultrastructural changes of mouse neurons were observed under a transmission electron microscope. ResultCompared with the normal group， the modeling shortened the latency to fall， increased the average total time in the pole test （P<0.01）， and up-regulated the levels of RhoA， ROCK2， MLC1， TNF-α， α-synuclein， and IL-1β in the substantia nigra （P<0.05）. Compared with the model group， different doses of Achyranthis Bidentatae Radix-Paeoniae Radix Alba and selegiline prolonged the latency to fall， shortened the average total time in the pole test （P<0.05， P<0.01）， and down-regulated the levels of ROCK2， MLC1， α-synuclein， TNF-α， and IL-1β in a dose-dependent manner （P<0.05）. Further， the modeling decreased the number of cytoplasmic organelles and caused mitochondrial swelling and abnormal shape of endoplasmic reticulum compared with the normal group. The neurons in high-dose Achyranthis Bidentatae Radix-Paeoniae Radix Alba and selegiline groups showed intact nuclei， clear cell boundary， and normal endoplasmic reticulum shape. ConclusionThe combination of Achyranthis Bidentatae Radix and Paeoniae Radix Alba may improve the motor coordination ability of Parkinson's disease mouse model with the syndrome of ascendant hyperactivity of liver yang by inhibiting the neuroinflammation mediated by the RhoA/ROCK2 signaling pathway in the brain.