ObjectiveTo investigate the mechanism of Hei Xiaoyaosan （HXS） in ameliorating cognitive impairment in the rat model of Alzheimer's disease （AD） by regulating the adenosine 5'-monophosphate-activated protein kinase （AMPK）/sterol regulatory element-binding protein 2 （SREBP2）/proprotein convertase subtilisin/kexin type 9 （PCSK9）/low-density lipoprotein receptor-related protein 1 （LRP-1） signaling pathway to clear amyloid-β （Aβ） from the peripheral circulation. MethodsNinety 8-week-old specific pathogen-free （SPF）-grade male Sprague-Dawley （SD） rats were acclimatized for 1 week. After acclimatization， 10 rats were randomly selected as the blank control group， and the remaining 80 rats were prepared for surgical modeling. Among the 80 rats for modeling， 70 were anesthetized and injected with 1 μL of amyloid-β_1-42 （Aβ_1-42） solution into the bilateral hippocampal CA1 region for the modeling of AD， and the remaining 10 were assigned to the sham operation group， which received an injection of 1 μL normal saline at the same anatomical site. The successfully modeled rats were randomly assigned into 6 groups （n=10 per group）： a model group， a donepezil hydrochloride group， an acadesine （AICAR， an AMPK agonist） group， and high-， medium-， and low-dose HXS groups. After 42 consecutive days of administration intervention， the Morris water maze test and T-maze test were performed to evaluate the learning and memory abilities of rats. Fluoro-Jade B （FJB） staining was conducted to observe pathological changes of neurons in the rat hippocampus， and thioflavin S staining to quantify the area of Aβ deposition in the hippocampal region. Immunofluorescence double staining （IF-DS） was performed to detect the expression of LRP-1 and Aβ signals in the liver tissue. Enzyme-linked immunosorbent assay （ELISA） was employed to measure the levels of Aβ_1-42 and soluble LRP-1 （sLRP-1） in the serum. Western blot was performed to determine the protein levels of AMPK， phosphorylated AMPK （p-AMPK）， SREBP2， PCSK9， and LRP-1 in the liver tissue. Real time polymerase chain reaction（Real-time PCR） was adopted to assess the mRNA levels of AMPK， SREBP2， PCSK9， and LRP-1 in the liver tissue. ResultsCompared with the blank control group， the model group showed increased total swimming distance on day 6 and path length in the target quadrant on day 7 （P<0.01）， a decreased correct alternation rate in the T-maze test （P<0.01）， disarrangement of hippocampal neurons， increased FJB-positive cells （P<0.01）， enlarged area of Aβ deposition （P<0.01）. reduced LRP-1 fluorescence signals and enhanced Aβ fluorescence signals in the liver tissue （P<0.01）， elevated serum level of Aβ_1-42， declined serum level of sLRP-1 （P<0.01）， downregulated protein levels of p-AMPK and LRP-1 as well as mRNA levels of AMPK and LRP-1， and upregulated protein and mRNA levels of SREBP2 and PCSK9 in the liver tissue （P<0.01）. Compared with the model group， the high-dose HXS group， donepezil hydrochloride group， and AICAR group exhibited reduced total swimming distance and target quadrant path length （P<0.05， P<0.01）， an increased correct alternation rate in the T-maze test （P<0.05）， decreased FJB-positive cells （P<0.01）， reduced Aβ deposition （P<0.01） in the hippocampal tissue， enhanced LRP-1 signals and weakened Aβ signals in the liver tissue （P<0.01）， a declined serum level of Aβ_1-42 and an elevated serum level of sLRP-1 （P<0.01）， upregulated protein levels of p-AMPK and LRP-1 as well as mRNA levels of AMPK and LRP-1， and downregulated protein and mRNA levels of SREBP2 and PCSK9 in the liver tissue （P<0.01）. ConclusionHei Xiaoyaosan can regulate the AMPK/SREBP2/PCSK9/LRP-1 signaling pathway to enhance the clearance of peripheral Aβ by the liver tissue and reduce Aβ deposition in the brain， thereby improving the learning and memory abilities of AD rats.

ObjectiveTo investigate the role and mechanism of Hei Xiaoyaosan in regulating asparaginyl endopeptidase （AEP） to inhibit tau protein （tau） phosphorylation， amyloid-beta protein （Aβ） deposition， and neuroinflammation in the prevention and treatment of Alzheimer's disease （AD）. MethodsNinety SPF-grade SD male rats of 8 weeks 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 （bilateral hippocampus injected with 1 μL Aβ_1-42 solution for the modeling of AD）. Fifty successfully modeled rats were selected and randomly assigned into the model， donepezil hydrochloride （positive control， 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. Rats were administrated with corresponding agents by gavage once a day for 42 days. Morris water maze and Y maze tests were carried out to assess the cognitive abilities of rats. Hematoxylin-eosin （HE） staining was employed to observe morphological changes in hippocampal neurons， and immunohistochemistry （IHC） was employed to assess phosphorylation （p）-tau and Aβ expression in the hippocampal tissue of rats. Enzyme-linked immunosorbent assay （ELISA） was employed to measure the levels of interleukin-1 beta （IL-1β）， interleukin-18 （IL-18）， and Aβ_1-42 in the hippocampal tissue. Western blot was employed to determine the protein levels of AEP， tau， phosphorylated tau （p-tau）， α-Syn （α-Syn）， phosphorylated α-Syn （p-α-Syn）， Toll-like receptor 2 （TLR2）， and NOD-like receptor thermal protein domain associated protein 3 （NLRP3）. Real time polymerase chain reaction （Real-time PCR） was employed to determine the mRNA levels of AEP， tau， α-Syn， TLR2， and NLRP3. ResultsCompared with the blank group， the model group showed prolonged escape latency， a decreased percentage of time spent in the platform quadrant， and a decreased alternation rate （P<0.01）， a reduced number， shrinkage， and increased vacuoles of hippocampal neurons， increased expression of p-tau and Aβ in the hippocampus （P<0.01）， elevated levels of IL-1β， IL-18， and Aβ_1-42， up-regulated protein and mRNA levels of AEP， tau， α-Syn， TLR2， and NLRP3， and up-regulated protein levels of p-tau and p-α-Syn （P<0.01）. Compared with the model group， the positive control group and the high-dose Hei Xiaoyaosan group exhibited shortened escape latency （P<0.01）， an increased percentage of retention time in the target quadrant， an increased alternation response rate （P<0.05， P<0.01）， alleviated neuronal shrinkage， regular morphology and arrangement of neurons in the hippocampal tissue， lowered levels of p-tau and Aβ in the hippocampal tissue （P<0.05， P<0.01）， declined levels of IL-1β， IL-18， and Aβ_1-42， downregulated mRNA and protein levels of AEP， tau， α-Syn， TLR2， and NLRP3， and downregulated protein levels of p-tau and p-α-Syn （P<0.05， P<0.01）. ConclusionHei Xiaoyaosan can protect hippocampal neurons and ameliorate cognitive impairment in the rat model of AD. Specifically， it may inhibit AEP to regulate tau phosphorylation， Aβ deposition， and neuroinflammation.

ObjectiveTo investigate the effects of Hei Xiaoyaosan on neuroinflammation in APP/PS1 mice and decipher the mechanism based on the C-X3-C chemokine ligand 1 （CX3CL1）-CX3CL1 receptor 1 （CX3CR1） signaling axis. MethodsSixty 16-week-old male APP/PS1 mice were selected and acclimatized for one week， and they were then randomly allocated into a model group， a CX3CL1 group （bilateral hippocampal injection of CX3CL1 at 0.5 g·L^-1）， and high-， medium-， and low-dose （22.10， 11.05， and 5.53 g·kg^-1， respectively） Hei Xiaoyaosan groups， with 12 mice in each group. Twelve age-matched male C57BL/6J mice served as the blank group （bilateral hippocampal injection of an equal volume of PBS）. The high-， medium-， and low-dose Hei Xiaoyaosan groups received corresponding drugs via gavage， while the blank group received an equal volume of normal saline， with an intervention period of 90 days. Morris water maze was used to assess learning and memory abilities. Nissl staining was performed to observe the pathological changes in neurons of the hippocampal CA1 region. Immunohistochemistry was adopted to detect amyloid-β_1-42 （Aβ_1-42） deposition in the hippocampal CA1 region. The immunofluorescence assay was employed to detect the expression of M1 and M2 microglial markers， including cluster of differentiation 86 （CD86）/ionized calcium-binding adapter molecule 1 （Iba-1） and arginase-1 （Arg1）/Iba1. Enzyme-linked immunosorbent assay （ELISA） was employed to measure the levels of interleukin-8 （IL-8） and interleukin-13 （IL-13） in the hippocampal tissue. Western blot was employed to determine the protein levels of CX3CL1， CX3CR1， CREB-binding protein （CBP）， cyclic AMP response element-binding protein （CREB）， phosphorylated （p）-CREB， and brain-derived neurotrophic factor （BDNF） in the hippocampal tissue. ResultsCompared with the blank group， the model group exhibited prolonged escape latency on day 5 and a reduced swimming distance in the target quadrant （P<0.01）， disarrangement of hippocampal neurons， with a reduced number of cells and uneven Nissl body staining， increased CD86/Iba1 expression， decreased Arg1/Iba1 expression （P<0.01）， enhanced Aβ expression （P<0.01）， an elevated IL-8 level and a declined IL-13 level （P<0.01）， and downregulated protein levels of CX3CL1， CX3CR1， CBP， p-CREB， and BDNF （P<0.01）. Compared with the model group， all treatment groups showed shortened escape latency on day 5 and an increased swimming distance in the target quadrant （P<0.05， P<0.01）， regular arrangement of neurons with an increased number and increased Nissl bodies， reduced CD86/Iba1 expression， increased Arg1/Iba1 and decreased Aβ expression （P<0.01）， and a declined IL-8 level and an elevated IL-13 level （P<0.05， P<0.01）. In the CX3CL1 group and the high- and medium-dose Hei Xiaoyaosan groups， the relative expression levels of CX3CL1， CX3CR1， CBP， and p-CREB were upregulated （P<0.01）. In the low-dose Hei Xiaoyaosan group， the relative expression levels of CX3CL1， CX3CR1， CBP， p-CREB/CREB， and BDNF were upregulated （P<0.05， P<0.01）. ConclusionHei Xiaoyaosan can improve learning and cognitive abilities in APP/PS1 mice. Specifically， it may regulate the CX3CL1/CX3CR1 signaling axis to activate the CREB/BDNF signaling pathway for the subsequent release of BDNF， modulation of microglial polarization， reduction of inflammatory cytokine levels， and attenuation of Aβ deposition.

ObjectiveTo investigate the effect and mechanism of Hei Xiaoyaosan in preventing and treating Alzheimer's disease （AD） by activating autophagy through regulating the adenosine monophosphate-activated protein kinase （AMPK）/UNC-51 like autophagy activating kinase 1 （ULK1） signaling pathway. MethodsNinety 8-week-old male SPF-grade SD rats were selected and randomized into two groups： a blank control group （n=10） and a modeling group （n=80）. From the modeling group， 10 rats were randomly assigned as a sham group （bilateral hippocampal injection of 1 μL normal saline）， while the remaining 70 rats were injected with 1 μL Aβ_1-42 solution bilaterally into the hippocampus to replicate the AD model. The Morris water maze test was conducted to screen the successfully modeled rats， which were then randomly allocated to the model， donepezil hydrochloride， 5-aminoimidazole-4-carboxamide 1-β-D-ribofuranoside （AICAR， an AMPK agonist）， and high-， medium-， and low-dose Hei Xiaoyaosan groups， with 10 rats per group. After 42 days of drug intervention， the Morris water maze and open field tests were conducted to assess learning and memory abilities and motor function. Pathological changes in the hippocampal tissue were observed by Nissl staining， and autophagy-related pathological damage was examined via transmission electron microscopy （TEM）. The expression of LC3 in the hippocampus was observed by immunofluorescence staining. The protein levels of AMPK， phosphorylate （p）-AMPK， ULK1， p-ULK1， p62， and autophagy related 7 （Atg7） were determined by Western blot， while the mRNA levels of AMPK and ULK1 were measured by Real-time polymerase chain reaction （Real-time PCR）. ResultsCompared with the blank control group， the model group showed increased escape latency （P<0.01） and decreased platform crossings （P<0.01） on day 6 in the water maze test， reduced total distance traveled and average speed in the open field test （P<0.01）， disarranged neurons with Nissl body loss and evident autophagic damage， weakened LC3 fluorescence signal （P<0.01）， downregulated protein levels of p-AMPK， p-ULK1， and Atg7 and mRNA levels of AMPK and ULK1 in the hippocampus （P<0.01）， and upregulated protein level of p62 （P<0.01）. Compared with the model group， the positive drug group， high-dose Hei Xiaoyaosan group， and AICAR group showed decreased escape latency （P<0.05， P<0.01） and increased platform crossings （P<0.01） on day 6， and increased total distance traveled and average speed in the open field test （P<0.05）. The positive drug group， high- and medium-dose Hei Xiaoyaosan groups， and the AICAR group showed alleviated cellular structural damage， regular neuronal arrangement， increased Nissl bodies， and orderly distribution of autophagosomes. Furthermore， the LC3 fluorescence intensity was enhanced in the positive drug group， high- and medium-dose Hei Xiaoyaosan groups， and the AICAR group （P<0.01）. The positive drug group， high-dose Hei Xiaoyaosan group， and the AICAR group exhibited upregulated protein and mRNA levels of p-AMPK and p-ULK1 （P<0.05， P<0.01）， upregulated protein level of Atg7 （P<0.05， P<0.01）， and downregulated protein level of p62 （P<0.01）. ConclusionHei Xiaoyaosan can improve learning and memory abilities and alleviate pathological status in the rat model of AD by regulating the AMPK/ULK1 signaling pathway， enhancing cellular autophagy， and repairing damaged nerve cells.

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.