ObjectiveTo explore the role and mechanism of Hei Xiaoyaosan in regulating the protein kinase B （Akt）/glycogen synthase kinase-3β （GSK-3β）/nuclear factor E₂-related factor 2 （Nrf2）/heme oxygenase-1 （HO-1） signaling pathway in cascade modulation of oxidative stress and apoptosis for preventing and treating Alzheimer's disease （AD）. MethodsNinety male SD rats of 4 months old were randomly assigned into a control group （n=10）， a sham group （with injection of 1 μL normal saline into bilateral hippocampi， n=10）， and a modeling group （with injection of 1 μL beta-amyloid 1-42 solution into bilateral hippocampi to induce AD， n=70）. One week after modeling， 50 successfully modeled rats were selected and randomly allocated into model， donepezil hydrochloride （0.45 mg·kg^-1）， and high-， medium-， and low-dose （15.30， 7.65， 3.82 g·kg^-1， respectively） Hei Xiaoyaosan groups. The rats were administrated with corresponding drugs once daily for six consecutive weeks. The Morris water maze was used to assess the learning and memory abilities of rats. Hematoxylin-eosin （HE） staining was performed to reveal hippocampal morphological changes in AD rats. Apoptosis in the hippocampal CA3 region was detected by terminal-deoxynucleotidyl transferase-mediated Nick end labeling. Immunofluorescence was used to visualize the expression of neuronal nuclear antigen （NeuN） in the CA1 region. Additionally， enzyme-linked immunosorbent assay was performed to assess the activities of glutathione peroxidase （GSH-Px）， glutathione-S-transferase （GST）， and catalase （CAT） in the hippocampus. Real-time PCR was conducted to measure the mRNA levels of Akt， GSK-3β， Nrf2， and HO-1， while Western blot was employed to determine the protein levels of phosphorylated Akt （p-Akt）/Akt， phosphorylated GSK-3β （p-GSK-3β）/GSK-3β， Nrf2， and HO-1. ResultsCompared with the control group， the model group on day 5 showed an increase in total swimming distance （P<0.01）， a reduction in the percentage of time spent in the target quadrant （P<0.01）， reduced and disarranged neurons， nuclear condensation， varying degrees of cellular damage， increased apoptosis of hippocampal neurons （P<0.01）， decreased NeuN content （P<0.01）， weakend activities of GSH-Px， GST， and CAT （P<0.01）， and down-regulated mRNA levels of Nrf2 and HO-1 （P<0.01） and protein levels of p-Akt/Akt， p-GSK-3β/GSK-3β， Nrf2， and HO-1 （P<0.01） in the hippocampus. Compared with the model group， donepezil hydrochloride and high， medium， and low doses of Hei Xiaoyaosan shortened the total swimming distance on day 5 （P<0.05， P<0.01）， increased the percentage of time spent in the target quadrant （P<0.05， P<0.01）， improved the arrangement and morphology of neurons， reduced nuclear condensation and the apoptosis rate of hippocampal neurons （P<0.01）， increased the NeuN content （P<0.01）， enhanced the activities of GSH-Px， GST， and CAT （P<0.05， P<0.01）， and up-regulated the mRNA levels of Nrf2 and HO-1 （P<0.05， P<0.01） and the protein levels of p-Akt/Akt， p-GSK-3β/GSK-3β， Nrf2， and HO-1 （P<0.05， P<0.01） in the hippocampus. ConclusionHei Xiaoyaosan can regulate the Akt/GSK-3β/Nrf2/HO-1 pathway to enhance the antioxidant stress capacity and inhibit neuron apoptosis to exert the neuroprotective effect， thereby ameliorating the cognitive dysfunction and pathological damage in AD rats.

ObjectiveTo explore the mechanism of Hei Xiaoyaosan in improving the cognitive function in Alzheimer's disease （AD） from cell apoptosis mediated by the phosphatidylinositol 3-kinase （PI3K）/protein kinase B （Akt）/nuclear factor kappa B （NF-κB） signaling pathway. MethodsFour-month-old SD male rats were randomly assigned into a blank group， a sham group， a model group， a donepezil hydrochloride （0.45 mg·kg^-1） group， and high-， medium-， and low-dose （15.30， 7.65， and 3.82 g·kg^-1， respectively） Hei Xiaoyaosan groups， with 10 rats in each group. The sham group received bilateral hippocampal injection of 1 μL normal saline， while the other groups received bilateral hippocampal injection of 1 μL beta-amyloid 1-42 （Aβ_1-42） solution for the modeling of AD. Rats were administrated with corresponding agents once a day for 42 consecutive days. The Morris water maze test was carried out to assess the learning and memory abilities of rats. Hematoxylin-eosin staining was employed to observe pathological changes in the hippocampus of rats. Enzyme-linked immunosorbent assay was employed to measure the levels of cysteinyl aspartate-specific proteinase-3 （Caspase-3）， B-cell lymphoma-2 （Bcl-2）， and Bcl-2-associated X protein （Bax）. Western blot was employed to determine the protein levels of PI3K， Akt， and NF-κB. A cell model of AD was established by co-culturing Aβ_1-42 and PC12 cells in vitro. Cell viability and apoptosis were detected by the cell-counting kit 8 （CCK-8） assay and flow cytometry （FC）， respectively. ResultsAnimal experiments showed that compared with the blank group， the model group had a prolonged escape latency （P<0.01）， a reduced number of crossing platforms （P<0.01）， disarrangement and a reduced number of hippocampal neurons， up-regulated expression of Bax and Caspase-3， down-regulated expression of Bcl-2 （P<0.01）， decreased p-PI3K/PI3K and p-Akt/Akt levels， and an increased p-NF-κB/NF-κB level （P<0.01）. Compared with the model group， donepezil hydrochloride and high- and medium-dose Hei Xiaoyaosan shortened the escape latency and increased the number of crossing platforms （P<0.05， P<0.01）， improved the arrangement and increased the number of hippocampal neurons， down-regulated the expression levels of Bax and Caspase-3， up-reguated the expression level of Bcl-2 （P<0.05， P<0.01）， increased the p-PI3K/PI3K and p-Akt/Akt levels （P<0.05， P<0.01）， and reduced the p-NF-κB/NF-κB level （P<0.05， P<0.01）. Cell experiments showed that compared with the blank group， the model group exhibited an increased apoptosis rate （P<0.01）. Compared with the model group， the serum containing Hei Xiaoyaosan at various doses improved the cell viability （P<0.01）， and the serum containing Hei Xiaoyaosan at the high dose decreased the cell apoptosis （P<0.01）. ConclusionHei Xiaoyaosan may improve the learning and memory abilities of AD model rats by regulating cell apoptosis， while increasing the vitality and reducing the apoptosis rate of AD model cells via the PI3K/Akt/NF-κB signaling pathway.

ObjectiveTo investigate the effects of Hei Xiaoyaosan on cognitive impairment and the histone deacetylase sirtuin-1 （SIRT1）/tumor suppressor p53/solute carrier family 7 member 11 （SLC7A11） signaling pathway in the rat model of Alzheimer's disease （AD）. MethodsA total of 90 16-week-old SPF-grade SD male rats were randomly assigned in a blank group （n=10）， a sham group （n=10， with injection of 1 μL normal saline into the bilateral hippocampi）， and an AD modeling group （n=70， with injection of 1 μL β amyloid 1-42 solution into the bilateral hippocampi）. According to the random number table method， fifty successfully modeled rats were assigned into model， donepezil hydrochloride （0.45 mg·kg^-1）， and high-， medium-， and low-dose （15.30， 7.65， and 3.82 g·kg^-1， respectively） Hei Xiaoyaosan groups， and they were administrated with corresponding agents via gavage once a day for 42 consecutive days. Morris water maze test was carried out to examine the cognitive function of rats. Nissl staining was employed to observe the morphology of hippocampal neurons in each group， and Prussian blue staining was used to detect iron deposition in the hippocampal tissue. Biochemical kits were used to measure the levels of superoxide dismutase （SOD）， malondialdehyde （MDA）， and iron ion （Fe²⁺） in the hippocampal tissue. Western blot and real-time quantitative polymerase chain reaction （Real-time PCR） were employed to determine the protein and mRNA levels， respectively， of SIRT1， p53， SLC7A11， glutathione peroxidase 4 （GPX4）， and acyl-CoA synthetase long-chain family member 4 （ACSL4） in the hippocampus. ResultsCompared with the blank group， the model group showed reductions in target quadrant movement distance （P<0.01） and target quadrant residence time （P<0.05）， disarrangement of hippocampal neurons， increased ferroptosis deposition in the hippocampus， a lowered level of SOD， risen levels of MDA and Fe²⁺ （P<0.05， P<0.01）， down-regulated protein and mRNA levels of SIRT1， SLC7A11， and GPX4 （P<0.05， P<0.01）， up-regulated protein and mRNA levels of p53 and ACSL4 （P<0.01）， and aggravated pathological process of AD. Compared with the model group， donepezil hydrochloride extended the target quadrant residence time and the target quadrant movement distance （P<0.05， P<0.01）. High- and medium- doses of Hei Xiaoyaosan extended the target quadrant residence time and the target quadrant movement distance （P<0.05， P<0.01）， improved the neuron arrangement and reduced the ferroptosis deposition in the hippocampus， elevated the SOD level， lowered the MDA and Fe²⁺ levels （P<0.05， P<0.01）， up-regulated the protein and mRNA levels of SIRT1， SLC7A11， and GPX4 （P<0.01， P<0.05）， and down-regulated the protein and mRNA levels of p53 and ACSL4 （P<0.05， P<0.01）. ConclusionHei Xiaoyaosan can regulate the SIRT1/p53/SLC7A11 signaling pathway to mitigate oxidative stress and inhibit ferroptosis， thereby ameliorating the cognitive dysfunction in AD rats.

ObjectiveTo observe the effects of Hei Xiaoyaosan on the learning and memory abilities of Alzheimer's disease model mice （APP/PS1 mice）， and to explore its mechanism through the inflammatory cascade mediated by nucleotide-binding oligomerization domain-like receptor family pyrin domain-containing 3 （NLRP3）/cysteine aspartate-specific protease （Caspase-1）/gasdermin D （GSDMD） signaling pathway. MethodsSPF-grade 4-month-old APP/PS1 mice were randomly divided into the model group， MCC950 group， and Hei Xiaoyaosan high-， medium-， and low-dose groups. C57BL/6J mice were used as the blank group. After 7 days of adaptive feeding， mice in each group were intervened. The Hei Xiaoyaosan high-， medium-， and low-dose groups were given corresponding doses by gavage （25.79， 12.90， 6.45 g·kg^-1·d^-1）， the MCC950 group was intraperitoneally injected with 10 mg·kg^-1·2 d^-1， and the blank group received the same volume of physiological saline by gavage. After 90 days of intervention， the learning and memory abilities were assessed using the Y maze and Morris water maze tests. The structural changes of hippocampal neurons were observed by hematoxylin-eosin （HE） staining. The expression of amyloid precursor protein （APP） in the hippocampal CA3 region was detected by immunohistochemistry. Enzyme-linked immunosorbent assay （ELISA） was used to measure the levels of interleukin （IL）-10， IL-18， and IL-1β in the hippocampus. Western blot was applied to detect the protein expression of NLRP3， Caspase-1， GSDMD， and GSDMD-N in the hippocampus. Immunofluorescence was used to detect the co-localization of GSDMD-N and ionized calcium-binding adapter molecule-1 （Iba-1） in the hippocampus. Results① In the Y maze test， compared with the blank group， the spontaneous alternation rate of the model group was significantly reduced （P<0.01）. Compared with the model group， the spontaneous alternation rate in the Hei Xiaoyaosan high- and low-dose groups was significantly increased （P<0.01）. ② In the Morris water maze test， during the 1-4 days of the location navigation test， the escape latency time of mice decreased with the extension of training time. On day 4， compared with the blank group， the model group showed a significantly increased escape latency （P<0.05）. Compared with the model group， the MCC950 group and the Hei Xiaoyaosan low-dose group showed significantly reduced escape latency （P<0.05）. In the spatial exploration experiment， compared with the blank group， the number of platform crossings in the model group was significantly reduced （P<0.01）. Compared with the model group， the Hei Xiaoyaosan low-dose group showed significantly increased platform crossings （P<0.05）. ③ HE staining showed that， compared with the blank group， the hippocampal CA3 cells of the model group were damaged， arranged loosely and irregularly， swollen， with unclear boundaries， and the nuclei were pyknotic and deeply stained. MCC950 and all doses of Hei Xiaoyaosan improved the hippocampal CA3 cell damage in APP/PS1 mice to varying degrees. ④ Immunohistochemical results indicated that， compared with the blank group， the expression of APP in the hippocampal CA3 region was significantly increased in the model group （P<0.01）. MCC950 and all doses of Hei Xiaoyaosan could reduce the expression of APP in the hippocampal CA3 region of APP/PS1 mice （P<0.01）. ⑤ ELISA results showed that the levels of IL-18 and IL-1β in the hippocampus of mice in the model group were significantly increased， and IL-10 levels were significantly reduced （P<0.01）. Compared with the model group， the IL-18 levels in the MCC950 group and the Hei Xiaoyaosan medium- and low-dose groups were significantly reduced （P<0.01）. IL-1β levels in the hippocampus of the MCC950 group and Hei Xiaoyaosan high-， medium-， and low-dose groups were significantly decreased （P<0.01）. The IL-10 levels in the hippocampus of the MCC950 group and the Hei Xiaoyaosan medium- and low-dose groups were increased （P<0.05， P<0.01）. ⑥ Western blot results showed that compared with the blank group， the protein levels of NLRP3， Caspase-1， GSDMD， and GSDMD-N in the hippocampus of the model group were significantly elevated （P<0.01）. Compared with the model group， the content of NLRP3 and Caspase-1 in the hippocampus of the treated groups was decreased （P<0.05， P<0.01）. The content of GSDMD in the hippocampus of the Hei Xiaoyaosan high-， medium-， and low-dose groups was reduced （P<0.05， P<0.01）， and the content of GSDMD-N in the hippocampus of the Hei Xiaoyaosan medium- and low-dose groups was decreased （P<0.05， P<0.01）. ⑦ Immunofluorescence results showed that， compared with the blank group， the co-expression of GSDMD-N and Iba-1 in the hippocampus of the model group was significantly increased （P<0.01）. Compared with the model group， the co-expression of GSDMD-N and Iba-1 in the treated groups was significantly reduced （P<0.01）. ConclusionHei Xiaoyaosan may regulate the NLRP3/Caspase-1/GSDMD signaling pathway to affect the release of inflammatory factors， alleviate neuroinflammation，improve hippocampal histopathological changes，and improve learning and memory deficits，thus providing potential therapeutic benefits for Alzheimer's disease.

ObjectiveTo explore the effect and mechanism of Hei Xiaoyaosan in regulating the tumor necrosis factor receptor superfamily member 6 （Fas）/Fas ligand （FasL）/cysteine protease-8 （Caspase-8）/cysteine protease-3 （Caspase-3） signaling pathway to intervene in neuronal apoptosis and prevent Alzheimer's disease （AD）. MethodNinety SPF-grade SD male rats of 4 months old were selected and randomly grouped as follows： 10 rats in the blank group， 10 rats in the sham group （bilateral hippocampus injected with 1 μL normal saline）， and 70 rats in the modeling group ［bilater hippocampus injected with 1 μL amyloid-beta protein 1-42 （Aβ_1-42） solution for the modeling of AD］. Fifty successfully modeled rats were selected and randomly assigned into model， donepezil hydrochloride （0.45 mg·kg^-1）， and high-， medium-， and low-dose （15.30， 7.65， 3.82 g·kg^-1） Hei Xiaoyaosan groups. Rats were administrated with corresponding agents by gavage once a day for 42 days. Terminal-deoxynucleoitidyl transferase-mediated nick end labeling （TUNEL） was employed to observe the apoptosis of neurons in the cortex and hippocampus， and immunohistochemistry （IHC） was used to detect the expression of B-cell lymphoma-2 （Bcl-2） and Bcl-2-associated X protein （Bax） in the hippocampus. Real-time fluorescence quantitative polymerase chain reaction（Real-time PCR） was employed to determine the mRNA levels of Fas， FasL， and Fas-associated protein with death domain （Fadd）. Western blot was used to determine the protein levels of Fas， FasL， Fadd， Caspase-3， cleved Caspase-3， Caspase-8， and cleved Caspase-8. ResultCompared with the blank group and sham group， the model group showed increased apoptosis rate in the cortex and hippocampus （P<0.01）， elevated Bax level （P<0.01）， lowered Bcl-2 level （P<0.01）， up-regulated mRNA levels of Fas， FasL， and Fadd in the hippocampus （P<0.01）， and up-regulated protein levels of Fas， FasL， Fadd， cleaved Caspase-3， and cleaved Caspase-8 （P<0.01）. Compared with the model group， donepezil hydrochloride and Hei Xiaoyaosan at high and medium doses decreased the apoptosis rate in the cortex and hippocampus （P<0.05， P<0.01）， lowered the Bax level （P<0.01）， elevated the Bcl-2 level （P<0.01）， and down-regulated the mRNA levels of Fas， FasL， and Fadd and the protein levels of Fas， FasL， Fadd， cleaved Caspase-3， and cleaved Caspase-8 （P<0.05， P<0.01） in the hippocampus. Low-dose Hei Xiaoyaosan decreased the apoptosis rate in the cortex and hippocampus （P<0.05， P<0.01）， lowered the Bcl-2 level （P<0.01）， and down-regulated the mRNA levels of FasL and Fadd （P<0.05） and the protein levels of Fas， FasL， Fadd， cleaved Caspase-3， and cleaved Caspase-8 （P<0.05） in the hippocampus. ConclusionHei Xiaoyaosan can protect neurons in the cortex and hippocampus of AD rats by inhibiting the apoptosis mediated by the Fas/FasL/Caspase-8/Caspase-3 signaling pathway.

ObjectiveTo explore the effect and mechanism of Hei Xiaoyaosan in modulating the synaptic plasticity in APP/PS1 mice by regulating the cyclic adenosine monophosphate （cAMP）/protein kinase A （PKA）/N-methyl-D-aspartate receptor （NMDAR） signaling pathway. MethodTwelve 4-month-old male C57BL/6J mice were selected as the blank control group， and 60 4-month-old male APP/PS1 double transgenic mice were randomized into model， KW-6002 （adenosine receptor antagonist， 3 mg·kg^-1）， and high-， medium-， and low-dose （22.10， 11.05， 5.53 g·kg^-1， respectively） Hei Xiaoyaosan groups， with 12 mice in each group. Mice were administrated with corresponding drugs for 90 days. Transmission electron microscopy was employed to observe the synaptic ultrastructure of hippocampal neurons， and Golgi staining was used to observe the dendritic spine density of neurons in hippocampal CA1 region. Western blot was employed to measure the protein levels of cAMP， PKA， N-methyl-D-aspartate receptors 1， 2A， and 2B （NR1， NR2A， and NR2B， respectively）， postsynaptic density protein 95 （PSD95）， and synapsin 1 （SYN1）. Real-time fluorescence quantitative polymerase chain reaction（Real-time PCR） was performed to determine the mRNA levels of cAMP， PKA， and NR1. Enzyme-linked immunosorbent assay was employed to determine the content of interleukin-12 （IL-12） and interleukin-4 （IL-4） in the hippocampus. ResultCompared with the blank group， the model group showed blurred boundaries between presynaptic membrane and postsynaptic membrane in hippocampal CA1 region， reduced and scattered synaptic vesicles， and decreased density of postsynaptic membrane， and irregular， disarranged， and loosened dendritic spines of neurons in hippocampal CA1 region （P<0.01）. In addition， the model group presented down-regulated protein levels of cAMP， PKA， NR1， NR2A， NR2B， PSD95， and SYN1 and mRNA levels of cAMP， PKA， and NR1， elevated IL-12 level， and lowered IL-4 level in the hippocampus （P<0.01）. Compared with the model group， the drug intervention groups showed clear and intact boundaries between presynaptic membrane and postsynaptic membrane in hippocampal CA1 region， increased synaptic vesicles with dense arrangement， increased density of postsynaptic membrane， and improved morphology， arrangement， and density of neuronal dendritic spines （P<0.05， P<0.01）. In addition， the drug interventions up-regulated the protein levels of cAMP， PKA， NR1， NR2A， NR2B， PSD95， and SYN1 （P<0.05，P<0.01） and mRNA levels of cAMP， PKA， and NR1 （P<0.01）， lowered the IL-12 level （P<0.01）， and elevated the IL-4 level （P<0.01） in the hippocampus. ConclusionHei Xiaoyaosan can improve the structure and morphology of hippocampal neurons in APP/PS1 mice by activating the cAMP/PKA/NMDAR signaling pathway and repairing synaptic plasticity.

ObjectiveTo investigate the role and mechanism of Hei Xiaoyaosan in intervening in oxidative stress in the rat model of Alzheimer's disease （AD） via modulating the rat sarcoma （RAS）/rapidly accelerating fibrosarcoma （RAF）/mitogen-activated protein kinase kinase （MEK）/extracellular signal-regulated kinase （ERK） signaling pathway. MethodOne hundred 4-month-old SPF-grade Wistar male rats were randomly grouped as follows： 10 in the blank group， 10 in the sham group （bilateral hippocampus injected with 1 μL normal saline）， and 80 in the modeling group ［bilateral hippocampus injected with 1 μL amyloid beta protein 1-42 （Aβ_1-42） solution for the modeling of AD］. Fifty rats qualified for modeling were selected and randomized into the model， donepezil hydrochloride （0.5 mg·kg^-1）， and high-， medium-， and low-dose （15.30， 7.65， 3.82 g·kg^-1， respectively） Hei Xiaoyaosan groups. The rats were administrated with corresponding drugs by gavage once a day for 42 consecutive days. At the end of gavage， Morris water maze test was performed to examine the learning and memory abilities of the rats， and Nissl staining was used to observe the pathological changes of neurons in CA3 region of the hippocampus. The immunofluorescence assay was used to observe Aβ deposition and tau phosphorylation. Western blot was employed to determine the protein levels of RAS， RAF， phosphorylated （p）-RAF， MEK， p-MEK， ERK， and p-ERK in the hippocampal tissue. Biochemical methods were used to determine the levels of reactive oxygen species （ROS）， malondialdehyde （MDA）， and superoxide dismutase （SOD） in the hippocampal tissue. ResultCompared with the sham group， the model group showed prolonged escape latency （P<0.01）， shortened swimming distance in the target quadrant （P<0.01）， reduced and uneven stained Nissl bodies， enhanced fluorescence intensity of Aβ and p-tau （P<0.01）， up-regulated protein levels of RAS， p-RAF， p-MEK， and p-ERK in the hippocampal tissue （P<0.01）， increased ROS and MDA content （P<0.01）， and decreased SOD activity （P<0.01） on day 5. Compared with the model group， donepezil hydrochloride and high-， medium-， and low-dose Hei Xiaoyaosan shortened the escape latency （P<0.01）， increased the swimming distance in the target quadrant （P<0.01）， improved the arrangement， morphology， and structures of neurons and the number and distribution of Nissl bodies， decreased the fluorescence intensity of Aβ and p-tau （P<0.01）， up-regulated the protein levels of RAS， p-RAF， p-MEK， and p-ERK （P<0.05， P<0.01）， decreased the ROS and MDA content （P<0.01）， and increased the SOD activity （P<0.01） on day 5. ConclusionHei Xiaoyaosan may ameliorate oxidative stress， reduce Aβ and p-tau levels， and inhibit hippocampal neuronal damage by regulating the RAS/RAF/MEK/ERK signaling pathway， thus improving learning and memory abilities.

Alzheimer's disease （AD） is a neurodegenerative disease that predominantly affects the elderly. It belongs to the category of dementia in traditional Chinese medicine （TCM）， with the onset and progression closely associated with the functions of the kidney， liver， and spleen. The classic TCM formula Hei Xiaoyaosan， which regulates the three Yin of liver， spleen， and kidney， shows broad prospects in treating neurodegenerative diseases. This article reviews the experimental studies reported in the past decade to summarize the mechanisms of Hei Xiaoyaosan and its active components in intervening in AD. Hei Xiaoyaosan can treat AD via multiple targets， levels， and aspects comprehensively. The clinical studies have demonstrated that Hei Xiaoyaosan alone or in combination with other therapies has a definite therapeutic effect on AD. Specifically， it can ameliorate the cognitive impairment， mitigate oxidative stress， and inhibit the overexpression of soluble apoptotic factors in AD patients. This review aims to provide a theoretical basis for the treatment of AD with Hei Xiaoyaosan and explore new research directions. Moreover， it gives new insights into the clinical application of Hei Xiaoyaosan and the development of products with both medicinal and edible values.

ObjectiveTo investigate the effect of Danzhi Xiaoyaosan on the phosphorylation of tau protein and different sites of glycogen synthase kinase-3β （GSK-3β） and phosphoseryl/suanyl phosphate protein phosphatase 2A （PP2A） in the hippocampus of rats with Alzheimer's disease （AD） and its mechanism. MethodThe rat model of AD was established by injecting okadaic acid into the bilateral hippocampus of 90 male Wistar rats in SPF grades. The rats with successful modeling were selected and randomly divided into model group， aricept group （0.5 mg·kg^-1）， and Danzhi Xiaoyaosan high， medium， and low groups （17.55， 8.77， and 4.38 g·kg^-1）， and then gavaged for 42 d， once a day. Morris water maze was used to detect the learning and memory ability of rats， Nissl's staining was used to observe the morphological structure of neurons in the hippocampus， and Real-time polymerase chain reaction （Real-time PCR） was used to detect the mRNA expression levels of tau protein， GSK-3β， and PP2A. Western blot was used to determine the protein expression levels of tau protein， GSK-3β， and PP2A. ResultAs compared with the control group， the learning and memory abilities of the rats in the model group were significantly decreased （P<0.01）， and the hippocampal CA3 region cells had abnormal structure， disorderly arrangement， and decreased number. The expression levels of GSK-3β mRNA， GSK-3β， p-GSK-3β-Tyr216， p-PP2A， and p-tau were increased in the model group as compared with the control group （P<0.01）， and those of p-GSK-3β-Ser9 and PP2A decreased significantly （P<0.01）. As compared with the model group， the learning and memory ability of the Aricept group and the Danzhi Xiaoyaosan groups were improved （P<0.05， P<0.01）， and the cell morphology and the number of hippocampal CA3 regions were better. The mRNA expression levels of PP2A and tau in the Aricept group were significantly up-regulated （P<0.05）， the mRNA expression level of GSK-3β was significantly down-regulated （P<0.01）， and the protein expression levels of GSK-3β， p-GSK-3β-Tyr216， and p-PP2A were down-regulated （P<0.05， P<0.01）， and the protein expression level of PP2A was significantly up-regulated （P<0.01）. As compared with the model group， the mRNA expression level of PP2A in the high-dose Danzhi Xiaoyaosan group was significantly up-regulated （P<0.01）， and that of GSK-3β was significantly down-regulated （P<0.01）， whereas the protein expression levels of p-PP2A， p-GSK-3β-Tyr216， and p-tau were down-regulated （P<0.05， P<0.01）， and the protein expression level of PP2A was significantly up-regulated （P<0.01）. As compared with the model group， the mRNA expression level of GSK-3β was significantly down-regulated in the medium-dose Danzhi Xiaoyaosan group （P<0.01）， the protein expression levels of GSK-3β， p-GSK-3β-Tyr216， and p-tau were down-regulated （P<0.05， P<0.01）， and the protein expression level of PP2A was significantly up-regulated （P<0.01）. As compared with the model group， the mRNA expression level of PP2A was significantly up-regulated in the low-dose Danzhi Xiaoyaosan group （P<0.01）， and that of GSK-3β was significantly down-regulated （P<0.01）， whereas the protein expression levels of GSK-3β and p-GSK-3β-Tyr216 were down-regulated （P<0.05， P<0.01）， and those of p-GSK-3β-Ser9 and PP2A were significantly up-regulated （P<0.01）. ConclusionDanzhi Xiaoyaosan can improve the learning and memory ability of rats with AD， and its mechanism may be related to the regulation of the activities of GSK-3β and PP2A protein-related sites and the phosphorylation of tau protein.

Alzheimer's disease （AD） is a neurological disease highly related to age， which is the main cause of senile dementia and the most common disease leading to the loss of daily living ability of the elderly. AD brings heavy mental burden and economic pressure to patients， families， and society. Traditional Chinese medicine （TCM） ascribes AD to category of "dementia"， believing that the treatment should start from kidney because kidney deficiency is the root cause. Combined with the physiological and pathological characteristics of liver， this paper proposed that liver-kidney homology was an important idea for the prevention and treatment of AD. The main pathological manifestations of AD were amyloid β-protein （Aβ） deposition and neurofibrillary tangles （NFT）， and the pathogenesis was complex. A growing number of studies showed that immune inflammation played an important role in the pathogenesis of AD. The important target of treating AD was the regulation of neuro-immune inflammation through the nuclear factor kappa B （NF-κB）/NOD-like receptor thermal protein domain associated protein 3 （NLRP3）/Caspase-1/interleukin-1β （IL-1β） signaling pathway. Based on the idea of liver-kidney homology， this paper selected the representative formula Hei Xiaoyaosan to explore its effect on the prevention and treatment of AD and the mechanism from the perspective of regulating NF-κB/NLRP3/Caspase-1/IL-1β signaling pathway and inhibiting neuro-immune inflammation， expecting to further promote the in-depth study on the prevention and treatment of AD， and provide references for the prevention and treatment of AD by TCM.