ObjectiveMultiple sclerosis (MS) is a chronic inflammatory demyelinating disease of the central nervous system (CNS); however, its underlying neurological pathogenic mechanisms remain incompletely understood. Endogenous formaldehyde (FA), a metabolic byproduct of methylation-demethylation cycles, has recently been implicated in neurotoxicity, oxidative damage, and cognitive impairment. This study aimed to investigate whether excessive FA contributes to myelin sheath demyelination in mice and to evaluate the protective effects and mechanisms of two FA-elimination strategies: sodium bisulfite (NaHSO₃), a classical FA scavenger, and polyethylene glycol-modified astaxanthin nanoparticles (PEG-ATX@NPs), a brain-targeted nano-antioxidant formulation. MethodsA chronic demyelination model was established by feeding female C57BL/6J mice a diet containing 0.2% cuprizone (CPZ) for four weeks, followed by a two-week intervention period. Eighty mice were randomly assigned to four groups: NS (normal saline), CPZ+NS, CPZ+NaHSO₃, and CPZ+PEG-ATX@NPs. Behavioral tests, including open-field, Y-maze, and pole-climbing assays, were conducted to assess locomotor activity, motor coordination, and working memory. FA levels in serum, corpus callosum, and spinal cord were measured using an Na-FA fluorescent probe and quantified via in vivo and ex vivo fluorescence imaging. Neuroinflammatory responses were evaluated by measuring TNF-α, IL-1β, and IL-6 levels using ELISA, while oxidative stress was assessed by reactive oxygen species (ROS) fluorescence intensity. Demyelination was examined via Luxol fast blue staining, and microglial activation was analyzed by Iba1 immunofluorescence. Correlation analyses were performed to explore relationships among FA levels, inflammatory cytokines, ROS intensity, and behavioral parameters. ResultsCompared with the NS group, mice in the CPZ+NS group exhibited significant weight loss, impaired motor coordination and memory, and markedly reduced myelin regeneration (P<0.05). FA levels and pro-inflammatory cytokines were significantly elevated in serum, corpus callosum, and spinal cord (P<0.05). FA-associated fluorescence in brain and spinal tissues, as well as ROS intensity across all tissues examined, also increased substantially (P<0.05). CPZ treatment induced pronounced microglial activation and severe demyelination in the corpus callosum (P<0.01). Both NaHSO₃ and PEG-ATX@NPs effectively reduced FA accumulation in the brain and spinal cord, attenuated demyelination, suppressed microglial activation, decreased inflammatory cytokine levels, and improved motor and cognitive performance. These results confirm that CPZ induced severe demyelination accompanied by oxidative stress, neuroinflammation, and abnormal FA accumulation. Following intervention with either NaHSO₃ or PEG-ATX@NPs, endogenous FA levels in the CNS were substantially reduced. Both treatments alleviated demyelination and significantly decreased the number of activated microglia. Levels of TNF-α, IL-1β, and IL-6 in serum, corpus callosum, and spinal cord were downregulated. Behavioral performance improved significantly, as evidenced by enhanced locomotor activity, better coordination, and improved memory function. These findings indicate that both FA-scavenging agents mitigate CPZ-induced biochemical and behavioral abnormalities. ConclusionThis study demonstrates that excessive endogenous FA is closely associated with cognitive impairment, inflammatory dysregulation, and demyelination in a CPZ-induced chronic demyelination mouse model. Clearing abnormally elevated FA effectively reduces neuroinflammation, suppresses microglial overactivation, decreases oxidative stress, and alleviates demyelination, ultimately improving motor and cognitive outcomes in mice. These results suggest that targeting endogenous FA represents a promising therapeutic strategy for MS and other demyelinating disorders. Further investigations are warranted to explore the long-term safety, dosage optimization, and molecular pathways involved in FA-mediated neurotoxicity.

ObjectiveMultiple sclerosis (MS) is a chronic inflammatory demyelinating disease of the central nervous system (CNS); however, its underlying neurological pathogenic mechanisms remain incompletely understood. Endogenous formaldehyde (FA), a metabolic byproduct of methylation-demethylation cycles, has recently been implicated in neurotoxicity, oxidative damage, and cognitive impairment. This study aimed to investigate whether excessive FA contributes to myelin sheath demyelination in mice and to evaluate the protective effects and mechanisms of two FA-elimination strategies: sodium bisulfite (NaHSO₃), a classical FA scavenger, and polyethylene glycol-modified astaxanthin nanoparticles (PEG-ATX@NPs), a brain-targeted nano-antioxidant formulation. MethodsA chronic demyelination model was established by feeding female C57BL/6J mice a diet containing 0.2% cuprizone (CPZ) for four weeks, followed by a two-week intervention period. Eighty mice were randomly assigned to four groups: NS (normal saline), CPZ+NS, CPZ+NaHSO₃, and CPZ+PEG-ATX@NPs. Behavioral tests, including open-field, Y-maze, and pole-climbing assays, were conducted to assess locomotor activity, motor coordination, and working memory. FA levels in serum, corpus callosum, and spinal cord were measured using an Na-FA fluorescent probe and quantified via in vivo and ex vivo fluorescence imaging. Neuroinflammatory responses were evaluated by measuring TNF-α, IL-1β, and IL-6 levels using ELISA, while oxidative stress was assessed by reactive oxygen species (ROS) fluorescence intensity. Demyelination was examined via Luxol fast blue staining, and microglial activation was analyzed by Iba1 immunofluorescence. Correlation analyses were performed to explore relationships among FA levels, inflammatory cytokines, ROS intensity, and behavioral parameters. ResultsCompared with the NS group, mice in the CPZ+NS group exhibited significant weight loss, impaired motor coordination and memory, and markedly reduced myelin regeneration (P<0.05). FA levels and pro-inflammatory cytokines were significantly elevated in serum, corpus callosum, and spinal cord (P<0.05). FA-associated fluorescence in brain and spinal tissues, as well as ROS intensity across all tissues examined, also increased substantially (P<0.05). CPZ treatment induced pronounced microglial activation and severe demyelination in the corpus callosum (P<0.01). Both NaHSO₃ and PEG-ATX@NPs effectively reduced FA accumulation in the brain and spinal cord, attenuated demyelination, suppressed microglial activation, decreased inflammatory cytokine levels, and improved motor and cognitive performance. These results confirm that CPZ induced severe demyelination accompanied by oxidative stress, neuroinflammation, and abnormal FA accumulation. Following intervention with either NaHSO₃ or PEG-ATX@NPs, endogenous FA levels in the CNS were substantially reduced. Both treatments alleviated demyelination and significantly decreased the number of activated microglia. Levels of TNF-α, IL-1β, and IL-6 in serum, corpus callosum, and spinal cord were downregulated. Behavioral performance improved significantly, as evidenced by enhanced locomotor activity, better coordination, and improved memory function. These findings indicate that both FA-scavenging agents mitigate CPZ-induced biochemical and behavioral abnormalities. ConclusionThis study demonstrates that excessive endogenous FA is closely associated with cognitive impairment, inflammatory dysregulation, and demyelination in a CPZ-induced chronic demyelination mouse model. Clearing abnormally elevated FA effectively reduces neuroinflammation, suppresses microglial overactivation, decreases oxidative stress, and alleviates demyelination, ultimately improving motor and cognitive outcomes in mice. These results suggest that targeting endogenous FA represents a promising therapeutic strategy for MS and other demyelinating disorders. Further investigations are warranted to explore the long-term safety, dosage optimization, and molecular pathways involved in FA-mediated neurotoxicity.

ObjectiveTo systematically compare the differential regulation of the maternal-fetal interface cell lineages and communication networks in the CBA/J×DBA/2 mouse model of recurrent pregnancy loss （RPL） by the two classic therapeutic methods-tonifying the kidney to stabilize the fetus and invigorating the spleen to stabilize the fetus （Shoutai Wan， Juyuan Jian）-of traditional Chinese medicine （TCM） at the single-cell resolution and clarify their modern scientific connotations. MethodsFemale non-pregnant CBA/J mice were caged with male BALB/c （blank group） and DBA/2 （modeling group） mice separately. Pregnant mice in the modeling group were randomly grouped as follows： high/low-dose Shoutai Wan， high/low-dose Juyuan Jian， model （RPL）， and positive control （dydrogesterone）， with 10 mice in each group. Starting from the day after the detection of the vaginal plug， mice were administrated with drugs or an equal volume of normal saline by gavage for 10 consecutive days. After the intervention， the following indicators were measured. ① Macroscopic evaluation： general conditions， uterine wet weight， embryo loss rate， four coagulation parameters ［prothrombin time （PT）， activated partial thromboplastin time （APTT）， fibrinogen （FIB）， and thrombin time （TT）］， and peripheral blood estradiol （E₂） and progesterone （Pg） levels. The decidua with embryos was stained with hematoxylin-eosin （HE） and evaluated by transmission electron microscopy （TEM）. The expression of B-cell lymphoma-2 （Bcl-2）， vascular endothelial growth factor （VEGF）， angiotensin Ⅱ （AngⅡ）， matrix metalloproteinase-2 （MMP-2）， interleukin-6 （IL-6）， leukemia inhibitory factor （LIF）， CXC chemokine ligand 12 （CXCL12）， and microtubule-associated protein 1 light chain 3 homolog （LC3）Ⅰ/Ⅱ was quantified by Western blot. ② Mechanism analysis at the single-cell level： The decidua with embryos from the blank， model， high-dose Shoutai Wan， and high-dose Juyuan Jian groups （6 mice per group， with 3 single-cell samples per group， totaling 24 mice） were analyzed by the BD Rhapsody™ platform， and the whole-cell atlas was drawn by uniform manifold approximation and projection （UMAP） dimensionality reduction clustering combined with the single-cell mouse cell atlas （scMCA）. The differentially expressed genes （DEGs） and cell interaction networks were analyzed via Gene Ontology （GO）， Kyoto Encyclopedia of Genes and Genomes （KEGG）， and CellChat， and the protein-protein interaction （PPI） map of subtype cells was constructed. The CytoTRACE pseudo-temporal analysis was performed to explore the developmental trajectories of core immune cells （natural killer cells， NK cells） from maternal and fetal sources. Results① Pathological and Western blot results indicated that compared with the blank group， the RPL group showed an increase in the embryo loss rate （P<0.01）， down-regulated expression of Bcl-2， LIF， MMP-2， and Vegf in the decidua with embryos （P<0.05）， up-regulated protein levels of CXCL-12， AngⅡ， and IL-6 （P<0.05）， blocked angiogenesis， apoptosis-inflammation imbalance， and coagulation dysfunction. Both prescriptions dose-dependently reduced the abortion rate and restored the angiogenesis-inflammation balance， and Shoutai pill showed superior performance in restoring the E₂ level to the Pg level （P<0.05）. ② Single-cell transcriptome analysis indicated that compared with the blank group， the RPL group showed differences in multiple key cell populations such as decidual cells， trophoblast cells， endothelial cells， erythroblasts， NK cells， and macrophages at the maternal-fetal interface. Immunity and angiogenesis were the key links in RPL. Compared with the RPL group， high-dose Shoutai Wan reversed the changes of NK cells in the embryonic layer （upregulating the mRNA levels of 17 genes and downregulating the mRNA levels of 29 genes） and macrophages （upregulating the mRNA levels of 117 genes and downregulating the mRNA levels of 53 genes） through the regulation of gene expression. High-dose Shoutai pill regulated the immune cells to affect unfolded proteins， cell adhesion， and programmed cell death， thereby promoting decidualization and angiogenesis and modulating embryo-membrane development. High-dose Juyuan Jian regulated the key subgroups of NK cells （up-regulating the mRNA levels of 9 genes and down-regulating the mRNA levels of 17 genes） and macrophages （up-regulating the mRNA levels of 110 genes and down-regulating the mRNA levels of 81 genes）， which affected decidual inflammation and apoptosis and intervened in glycolysis. ③ The pseudo-temporal analysis and communication network indicated that the communication frequency of the RPL group decreased. High-dose Shoutai Wan restored maternal-fetal tolerance through pathways such as NKG2D， CDH5， GDF， and FASLG. High-dose Juyuan Jian enhanced the IL-6/LIFR/JAK/signal transducer and activator of transcription 3 （STAT3） and desmosome/SEMA6/tumor necrosis factor-like weak inducer of apoptosis （TWEAK） signaling to improve endometrial receptivity. The RPL group showed an increased proportion of toxic dNK7， a decreased proportion of reparative dNK4， and blocked embryo fNK1. High-dose Shoutai Wan down-regulated dNK7 and up-regulated dNK4. High-dose Juyuan Jian inhibited the terminal differentiation of dNK7 and up-regulated LILRB1， thus restoring the balance of cytotoxicity and repair. ConclusionBoth the kidney-tonifying and spleen-invigorating methods are effective in treating RPL. NK and macrophages are the key immune cells in the interaction between the embryo and the membrane. The kidney-tonifying method （Shoutai Wan） has an advantage in regulating the phenotypes of unfolded protein， cell adhesion， and programmed cell death， and shows expression characteristics closer to the physiological state in the regulation of NKG2D and CDH5 signals. The spleen-invigorating method （Juyuan Jian） has an advantage in regulating epithelial-mesenchymal transition （EMT）， angiogenesis， and glycolysis and shows higher communication intensity in the IL-6 and LIFR pathways.

ObjectiveTo investigate whether Bushen Huoxue prescription improves embryo implantation through regulating exosomal miRNA to enhance maternal-fetal interface communication based on Bushen Huoxue therapy. MethodsIn the animal experiment， all the rats （except for the blank group） were administered hydroxyurea （450 mg·kg^-1） via gavage for 10 d， as well as epinephrine （0.3 mg·kg^-1） and mifepristone （5.5 mg·kg^-1） via subcutaneous injection for 7 d to establish an implantation disorder model of kidney deficiency and blood stasis type. The Bushen Huoxue prescription （BSHX） groups were administered the prescription at different doses （7.30 g·kg^-1 for the high-dose group， 3.65 g·kg^-1 for the medium-dose group， and 1.83 g·kg^-1 for the low-dose group） via gavage. The dydrogesterone group was administered the corresponding medicine （2.63 mg·kg^-1） via gavage. After intervention for 10 days， uterine histopathological changes were observed via hematoxylin-eosin （HE） staining. Mucin （MUC1）， forkhead box protein O1 （FoxO1）， and homeobox A10 （HoxA10） expression levels were detected by Real-time fluorescence quantitative polymerase chain reaction （Real-time PCR） and Western blot. Cell experiment selected primary endometrial epithelial cells （EEC） and trophoblast cells （TC） as research subjects. Exosome-free medicated serum was prepared by ultracentrifugation and cultured in complete medium. Exosomes were isolated from cell supernatants by ultracentrifugation for cross-co-culture. After 48 h， migration and invasion abilities were assessed by scratch and Transwell assays. Sequencing was then performed on EEC-origin exosomal miRNA. ResultsThe model rats exhibited thin endometrium， along with reduced blood vessels， glandules， and pinopode numbers. BSHX improved endometrial morphology and increased pinopode numbers. MUC1， FoxO1， and HoxA10 expressions were downregulated in the model rats， while these parameters were upregulated after BSHX medium- and high-dose intervention. In the cell experiment， after exosome-free medicated serum intervention for 24 h， migration and invasion abilities were enhanced in the BSHX groups （P<0.01）. In EEC-origin exosomal miRNA sequencing， gene ontology （GO） and Kyoto Encyclopedia of Genes and Genomes （KEGG） analyses revealed enrichment in biological processes （gastrulation， neuronal differentiation， alongside cell development and regeneration）， involving the mitogen-activated protein kinase （MAPK）， FoxO1， Wnt， mammalian target of rapamycin （mTOR）， and tumor necrosis factor （TNF） signaling pathways. ConclusionBSHX promotes embryo implantation by improving endometrial receptivity via regulating exosomal miRNA. These findings provide potential targets for exosomal miRNA-based assisted reproductive strategies and a novel theoretical basis for infertility treatment by traditional Chinese medicine.

[Objective] To retrospectively analyse the serological characteristics of hemolytic transfusion reactions caused by Rh and Kidd antibodies, and to provide reference for safe, timely, and effective blood transfusion. [Methods] Two cases of patients with RhCcEe and Kidd blood type who experienced allogeneic transfusion at Dazhou Central Hospital were selected. A series of immunohematological tests were performed, including ABO, RhDCcEe and Kidd blood typing, unexpected antibody screening and identification, crossmatching, direct antiglobulin test, acid elution test, and capillary centrifugation to separate the patient's own red blood cells from donated red blood cells. [Results] Unexpected antibody screening, antibody identification, and direct antiglobulin test were positive in both patients. Case 1 had anti-Jk in the plasma, but no specific antibodies were found in the eluate. Case 2 had anti-c and E in the plasma, and anti-E was detected in the eluate. High-speed capillary centrifugation revealed corresponding antigen-positive erythrocytes at the distal end of the blood samples of both patients. [Conclusion] Case 1 received Kidd allogeneic red blood cells, and case 2 received RhCcEe allogeneic red blood cells, and both patients developed the corresponding unexpected antibodies, which led to the occurrence of immune haemolytic blood transfusion reaction.

Background: s/Aims: Non-invasive models stratifying clinically significant portal hypertension (CSPH) are limited. Herein, we developed a new non-invasive model for predicting CSPH in patients with compensated cirrhosis and investigated whether carvedilol can prevent hepatic decompensation in patients with high-risk CSPH stratified using the new model. Methods: Non-invasive risk factors of CSPH were identified via systematic review and meta-analysis of studies involving patients with hepatic venous pressure gradient (HVPG). A new non-invasive model was validated for various performance aspects in three cohorts, i.e., a multicenter HVPG cohort, a follow-up cohort, and a carvediloltreating cohort. Results: In the meta-analysis with six studies (n=819), liver stiffness measurement and platelet count were identified as independent risk factors for CSPH and were used to develop the new “CSPH risk” model. In the HVPG cohort (n=151), the new model accurately predicted CSPH with cutoff values of 0 and –0.68 for ruling in and out CSPH, respectively. In the follow-up cohort (n=1,102), the cumulative incidences of decompensation events significantly differed using the cutoff values of <–0.68 (low-risk), –0.68 to 0 (medium-risk), and >0 (high-risk). In the carvediloltreated cohort, patients with high-risk CSPH treated with carvedilol (n=81) had lower rates of decompensation events than non-selective beta-blockers untreated patients with high-risk CSPH (n=613 before propensity score matching [PSM], n=162 after PSM). Conclusions Treatment with carvedilol significantly reduces the risk of hepatic decompensation in patients with high-risk CSPH stratified by the new model.

Objective:To investigate the expressions of serum cytokines in patients with autoimmune retinopathy (AIR), and their association with disease diagnosis as well as clinical features.Methods:A prospective case-control study was conducted.A total of 90 eyes of 45 AIR patients were consecutively collected in Beijing Tongren Hospital from September 2018 to December 2023.Additionally, age-matched 43 controls (86 eyes) were enrolled, consisting of 21 patients (42 eyes) with retinitis pigmentosa as a disease control group and 22 healthy subjects (44 eyes) as a normal control group.The main clinical outcome measures included best-corrected visual acuity (BCVA), mean deviation (MD) of visual field, central retinal thickness and the maximal response amplitude and implicit time of full-field electroretinography (ff-ERG). A total of 21 serum cytokines were detected by Luminex multiple cytokines assay or ELISA.Differences in serum cytokine concentrations of among groups, the correlation between cytokine levels and clinical outcomes, and the contribution of cytokines to the diagnosis of AIR were analyzed.This study adhered to the Declaration of Helsinki.The study protocol was approved by the Ethics Committee of Beijing Tongren Hospital (No.TRECKY2018-048). Written informed consent was obtained from each subject.Results:In AIR patients, the expression levels of Th1-type cytokines or receptors (including interferon-γ[IFN-γ], interleukin [IL]-8, C-X-C motif chemokine ligand [CXCL]9, and CXCL10) and Th17-type cytokines (including IL-17 and IL-6) were elevated.There were statistically significant overall differences in pro-inflammatory cytokines/chemokines (IL-6, IL-8, CXCL10, IL-10, IFN-γ, IL-17, C-X3-C motif chemokine ligand 1 [CX3CL]1, CXCL9) among the three groups ( H=10.823, 10.816, 9.633, 10.103, 23.670, 16.493, 9.050, 9.253; all P<0.05). Compared with the disease control group and the healthy control group, the IFN-γ level was significantly increased in the AIR group (both P=0.001). Compared with the healthy control group, the serum levels of IL-6, IL-8, CXCL10, IL-10, IL-17, and CXCL9 in the AIR group were significantly elevated (all P<0.05). The serum level of CX3CL1 was significantly higher in the AIR group than in the disease control group ( P=0.039). The serum level of IFN-γ was significantly higher in the AIR group than in the healthy control and disease control groups, but no association with AIR diagnosis was found ( OR=1.402, 95% CI: 0.710-2.870, P=0.245). Multilevel mixed-effects regression modeling analysis showed that the serum levels of IL-8 and CXCL9 in AIR patients were positively correlated with LogMAR BCVA ( β=0.028, P=0.033; β=0.023, P=0.003). The C-C motif chemokine ligand 11 level was positively correlated with implicit time of ERG a-wave ( β=13.950, P<0.001). The tumor necrosis factor-α level was positively correlated with MD value of visual field ( β=6.310, P=0.002). Granulocyte-macrophage colony-stimulating factor was negatively correlated with the amplitude of ERG a-wave and granulocyte colony-stimulating factor was negatively correlated with ERG b-wave amplitude ( β=-152.700, P<0.001; β=-14.790, P=0.003). Conclusions:Serum Th1 and Th17-type cytokines/chemokines may be involved in the pathogenesis of AIR and are related to disease severity.

Objective To evaluate and compare the performance of the Chronic Kidney Disease Epidemi-ology Collaboration(CKD-EPI)equation,the abbreviated Modification of Diet in Renal Disease(aMDRD)equa-tion,the Cockroft-Gault(C-G)formula,the Mayo Clinic Quadratic(MCQ)equation,and the Berlin Initiative Study 1(BIS1)equation in determining renal function among critically ill patients,and to identify the most appro-priate method for clinical application.Methods Critically ill patients admitted to the Intensive Care Units of the Department of Geriatric Medicine at the First Affiliated Hospital of Nanjing Medical University(Jiangsu Province Hospital)between June 2020 and June 2022 were included.Their renal function was assessed within 48 hours of admission using the 24-hour creatinine clearance rate(CrCl24h)as the reference standard,and compared with the CKD-EPI equation,aMDRD equation,C-G formula,MCQ equation,and BIS1 equation.The precision and accuracy of each equation in evaluating renal function in critically ill patients were analyzed.Results Total of 534 patients were included in the study.(1)The aMDRD equation exhibited the least bias(-3.91),yet the accuracy of the five estimated glomerular filtration rate(eGFR)equations was relatively low,ranging from 42.9%to 63.1%.(2)For renal function grading,the weighted κ agreement values between the CKD-EPI equation,aMDRD equation,C-G formula,MCQ equation,BIS1 equation,and CrCl24h were 0.464,0.555,0.403,0.405,and 0.159,respectively(all P<0.001).(3)Among patients with severe kidney function decline[CrCl24h≤60 mL/(min·1.73 m2)],the eGFR value derived from the C-G formula was the lowest,while that from the BIS1 equation was the highest.In patients with normal or moderately reduced renal function[60 mL/(min·1.73 m2)130 mL/(min·1.73 m2)],the eGFR value of the BIS1 equation was the lowest,and the aMDRD equation produced the highest eGFR value.(4)When renal function was severely decreased or augmented[CrCl24h>130 mL/(min·1.73 m2)],the accuracy of the CKD-EPI and MCQ equations declined.Conversely,as creatinine clearance increased,the accuracy of the aMDRD equation improved gradually.The C-G formula demonstrated an opposite trend compared to the aMDRD equation,and the BIS1 equation exhibited low accuracy across all groups.(5)The optimal critical values[mL/(min·m2)]for diagnosing augmented renal clearance(ARC)using the five eGFR equations were as follows:eGFRCKD-EPI:91.1,eGFRaMDRD:99.84,eGFRC-G:76.27,eGFRMCQ:100.87,eGFRBIS1:82.36.Conclusions The precision and accuracy of the five eGFR equations are relatively low,making them unsuitable for assessing renal function in critically ill patients.Collecting 24-hour urine to calculate creatinine clearance remains an essential method for evaluating renal function in this population.In the absence of early CrCl24h data upon ICU admission,the cut-off values of the eGFR equa-tions may serve as a tool for the early identification of ARC.Additionally,the aMDRD equation can provide a rough estimate of creatinine clearance in critically ill patients.

Objective:To investigate the effects and mechanisms of subchronic exposure to pyrethrin on the mice nervous system.Methods:Twenty-four male mice were randomly divided into a control group,low-,medium-,and high-dose groups,and were exposed continuously for 28 days.The control group received corn oil.The general condi-tion of the mice was observed,and the body weight and brain organ coefficient were measured.Neurobehavioral tests were conducted after the exposure period.The histopathological changes of the hippocampus in mice were observed by HE and nissl staining.The activities of lactate dehydrogenase(LDH),superoxide dismutase(SOD),catalase(CAT)and the contents of malondialdehyde(MDA),glutathione(GSH),acetylcholine(ACh)and glutamate(Glu)in brain tissue of mice were detected by biochemical kit.The Western blot was employed to measure the expression levels of kelch-like ech-associated protein 1(Keap1),nuclearfactorerythroid2-relatedfactor2(Nrf2),and heme oxygenase 1(HO-1)in brain tissue of mice.Results:Compared with the control group,the body weight of the mice in the high-dose group decreased,the brain organ coefficient increased,and the neurological function test showed that the mice had reduced autonomic activity,delayed nerve reflex,and impaired sensory and motor function.Histopathology showed that the hippocampal neurons in the middle-and high-dose groups presented with pyknosis,vacuolization,and disordered arrangement of the CA3 area.Biochemical analysis indicated that in the brain tissue of mice,the activity of LDH and the content of MDA were increased in the medium-and high-dose groups,while the activity of CAT and the content of GSH were decreased.The content of Glu was increased and the content of ACh was decreased.The activity of SOD was reduced in the low-,medium-,and high-dose groups.Western blot analysis showed that the expression of HO-1 and Nrf2 protein in the brain tissue of mice in the middle-and high-dose groups was down-regulated,while the expression of Keap1 protein in the high-dose group was up-regulated.Conclusion:Pyrethrin may cause damage to the nervous system by affecting the Keap1/Nrf2/HO-1 signaling pathway and neurotransmitter levels.