Exercise fatigue is a complex physiological and psychological phenomenon that includes peripheral fatigue in the muscles and central fatigue in the brain. Peripheral fatigue refers to the loss of force caused at the distal end of the neuromuscular junction, whereas central fatigue involves decreased motor output from the primary motor cortex, which is associated with modulations at anatomical sites proximal to nerves that innervate skeletal muscle. The central regulatory failure reflects a progressive decline in the central nervous system’s capacity to recruit motor units during sustained physical activity. Emerging evidence highlights the critical involvement of central neurochemical regulation in fatigue development, particularly through neurotransmitter-mediated modulation. Alterations in neurotransmitter release and receptor activity could influence excitatory and inhibitory signal pathways, thus modulating the perception of fatigue and exercise performance. Increased serotonin (5-HT) could increase perception of effort and lethargy, reduce motor drive to continue exercising, and contribute to exercise fatigue. Decreased dopamine (DA) and noradrenaline (NE) neurotransmission can negatively impact arousal, mood, motivation, and reward mechanisms and impair exercise performance. Furthermore, the serotonergic and dopaminergic systems interact with each other; a low 5-HT/DA ratio enhances motor motivation and improves performance, and a high 5-HT/DA ratio heightens fatigue perception and leads to decreased performance. The expression and activity of neurotransmitter receptors would be changed during prolonged exercise to fatigue, affecting the transmission of nerve signals. Prolonged high-intensity exercise causes excess 5-HT to overflow from the synaptic cleft to the axonal initial segment and activates the 5-HT1A receptor, thereby inhibiting the action potential of motor neurons and affecting the recruitment of motor units. During exercise to fatigue, the DA secretion is decreased, which blocks the binding of DA to D1 receptor in the caudate putamen and inhibits the activation of the direct pathway of the basal ganglia to suppress movement, meanwhile the binding of DA to D2 receptor is restrained in the caudate putamen, which activates the indirect pathway of the basal ganglia to influence motivation. Furthermore, other neurotransmitters and their receptors, such as adenosine (ADO), glutamic acid (Glu), and γ‑aminobutyric acid (GABA) also play important roles in regulating neurotransmitter balance and fatigue. The occurrence of central fatigue is not the result of the action of a single neurotransmitter system, but a comprehensive manifestation of the interaction between multiple neurotransmitters. This review explores the important role of neurotransmitters and their receptors in central motor fatigue, reveals the dynamic changes of different neurotransmitters such as 5-HT, DA, NE, and ADO during exercise, and summarizes the mechanisms by which these neurotransmitters and their receptors regulate fatigue perception and exercise performance through complex interactions. Besides, this study presents pharmacological evidence that drugs such as agonists, antagonists, and reuptake inhibitors could affect exercise performance by regulating the metabolic changes of neurotransmitters. Recently, emerging interventions such as dietary bioactive components intake and transcranial electrical stimulation may provide new ideas and strategies for the prevention and alleviation of exercise fatigue by regulating neurotransmitter levels and receptor activity. Overall, this work offers new theoretical insights into the understanding of exercise central fatigue, and future research should further investigate the relationship between neurotransmitters and their receptors and exercise fatigue.

ObjectiveTo investigate the effects of jujuboside A （JuA） on the learning and memory abilities and histopathological changes in the rat model of vascular cognitive impairment （VCI） and explore the potential mechanisms by which JuA treats VCI. MethodsA total of 50 male SPF-grade SD rats were randomized into a sham operation group （n=10）， a blank control group （n=10）， and a modeling group （n=30）. The rats in the modeling group underwent bilateral carotid artery ligation （2-VO） for the modeling of VCI. After stabilization， the VCI rats were randomized into model， JuA （20 mg·kg^-¹）， and donepezil （0.45 mg·kg^-¹） groups. After 4 weeks of gavage， the novel object recognition and Morris water maze tests were conducted to evaluate the learning and memory abilities of rats. Nissl staining was employed to evaluate the morphology and number of hippocampal neurons. Real-time PCR was employed to measure the mRNA levels of glycogen synthase kinase-3β （GSK-3β）， cAMP response element-binding protein （CREB）， B cell lymphoma-2 （Bcl-2）， phosphatidylinositol 3-kinase （PI3K）， and protein kinase B （Akt） in the hippocampal tissue. Western blot was employed to quantify the protein levels of GSK-3β， p-GSK-3β， p-CREB， Bcl-2， PI3K， p-PI3K， Akt， and p-Akt in the hippocampal tissue. ResultCompared with the sham operation group， the model group exhibited declines in the learning and memory abilities （P<0.01）， neuronal damage and decreased neurons in the hippocampal CA1 region （P<0.01）， up-regulation in the mRNA level of GSK-3β （P<0.01）， and down-regulation in the mRNA levels of PI3K， Akt， CREB， and Bcl-2， as well as the protein levels of p-PI3K， p-Akt， p-GSK-3β， p-CREB， and Bcl-2 （P<0.01）. In comparison to the model group， both the JuA and donepezil groups demonstrated improvements in the learning and memory abilities （P<0.05， P<0.01）， with reduced neuronal damage and increased neurons （P<0.05， P<0.01）. In addition， the two groups showed down-regulation in the mRNA level of GSK-3β （P<0.01） and up-regulation in the mRNA levels of PI3K， Akt， CREB， and Bcl-2 and the protein levels of p-PI3K， p-Akt， p-GSK-3β， p-CREB， and Bcl-2 （P<0.05， P<0.01）. There were no statistically significant differences between the blank control and sham operation groups in terms of the learning and memory abilities， neuron count， and mRNA and protein levels of PI3K/Akt/GSK-3β pathway-related factors. ConclusionJuA can ameliorate the cognitive impairment in the rat model of VCI by activating the PI3K/Akt signaling pathway， reducing the apoptosis of hippocampal neurons， and alleviating the hippocampal neuronal damage.

Myelin is an essential structure that facilitates rapid saltatory conduction in the nervous system. Discrepancies in myelin microstructure are a hallmark of numerous neurological disorders, rendering the assessment of myelin integrity and content an indispensable tool in clinical diagnostics and neuroscience research. Extensive research has been dedicated to scrutinizing its biochemical makeup and morphology under normal, pathological, and experimental conditions over the years. In this review, we present an updated summary of the myelin sheath's structure, composition, and developmental trajectory. We systematically enumerate and contrast eight prevalent myelin staining techniques across dimensions of sensitivity, specificity, and resolution, delving into their underlying staining principles. With an initial application of myelin histology on the mouse demyelination model, our review accentuates the accurate delineation of myelination and the microstructural analysis of the myelin sheath. Such insights are anticipated to significantly contribute to the evaluation and understanding of white matter pathologies.
Myelin Sheath/metabolism* ; Animals ; Humans ; Demyelinating Diseases/pathology* ; Staining and Labeling/methods*

ObjectiveTo investigate the mechanism by which Huanglian Jiedutang （HLJDT） inhibits pyroptosis and neuroinflammation in Alzheimer's disease （AD） mice via the NOD-like receptor protein 3 （NLRP3）/cysteinyl aspartate-specific protease-1 （Caspase）-1/gasdermin D （GSDMD） pathway. MethodsThirty APP/PS1 double transgenic mice were randomly and evenly divided into the model group （model group）， the positive control group （Donepezil group， 0.65 mg·kg^-1）， and the HLJDT treatment group （HLJDT group， 5.2 g·kg^-1）. Ten C57BL/6 mice were assigned to the blank control group （control group）. The Morris water maze and novel object recognition tests were used to evaluate learning and memory abilities. Nissl staining was employed to observe the morphology， quantity， and distribution of neurons in the hippocampal region. Golgi staining was used to examine the morphology and density of neuronal dendritic spines in the hippocampus. Real-time quantitative polymerase chain reaction （Real-time PCR） was performed to detect the mRNA expression of neuroinflammation-related factors and genes in the NLRP3/Caspase-1/GSDMD pyroptosis pathway in the hippocampus. Western blot was used to detect the expression of postsynaptic density protein 95 （PSD95）， amyloid precursor protein （APP）， inflammatory factors including nuclear factor-κB （NF-κB）， phosphorylated NF-κB （p-NF-κB）， tumor necrosis factor-α （TNF-α）， interleukin-1β （IL-1β）， as well as pyroptosis pathway-related proteins including NLRP3， Caspase-1， GSDMD， and GSDMD-N. ResultsCompared with the control group， the model group exhibited significantly decreased learning and memory abilities （P<0.01）， reduced numbers of neurons in the hippocampal CA3 region and dendritic spines in the hippocampal CA1 region （P<0.01）， and significantly increased hippocampal mRNA expression levels of NLRP3， Caspase-1， GSDMD， NF-κB， TNF-α， IL-1β， and IL-18 （P<0.01）. Protein levels of PSD95 were markedly decreased， while the expression levels of NLRP3， Caspase-1， GSDMD， p-NF-κB/NF-κB， TNF-α， IL-1β， and APP were significantly elevated （P<0.01）. Compared with the model group， both the Donepezil and HLJDT groups showed significantly improved learning and memory abilities （P<0.05， P<0.01）， increased numbers of hippocampal neurons in the hippocampal CA3 region and dendritic spines in the hippocampal CA1 region （P<0.01）， and significantly decreased hippocampal mRNA expression levels of NLRP3， Caspase-1， GSDMD， NF-κB， TNF-α， IL-1β， and IL-18 （P<0.05， P<0.01）. Protein levels of NLRP3， Caspase-1， GSDMD， p-NF-κB/NF-κB， TNF-α， IL-1β， and APP were significantly downregulated， while PSD95 expression was significantly upregulated （P<0.05， P<0.01）. There was no statistically significant difference in GSDMD-N levels in the Donepezil group， while GSDMD-N expression was significantly decreased in the HLJDT group （P<0.05）. ConclusionThis study confirms that HLJDT can improve learning and memory abilities in APP/PS1 double transgenic mice， and attenuate neuronal loss and synaptic damage， possibly through inhibition of pyroptosis via the NLRP3/Caspase-1/GSDMD pathway.

ObjectiveTo investigate the mechanism by which Huanglian Jiedutang （HLJDT） inhibits pyroptosis and neuroinflammation in Alzheimer's disease （AD） mice via the NOD-like receptor protein 3 （NLRP3）/cysteinyl aspartate-specific protease-1 （Caspase）-1/gasdermin D （GSDMD） pathway. MethodsThirty APP/PS1 double transgenic mice were randomly and evenly divided into the model group （model group）， the positive control group （Donepezil group， 0.65 mg·kg^-1）， and the HLJDT treatment group （HLJDT group， 5.2 g·kg^-1）. Ten C57BL/6 mice were assigned to the blank control group （control group）. The Morris water maze and novel object recognition tests were used to evaluate learning and memory abilities. Nissl staining was employed to observe the morphology， quantity， and distribution of neurons in the hippocampal region. Golgi staining was used to examine the morphology and density of neuronal dendritic spines in the hippocampus. Real-time quantitative polymerase chain reaction （Real-time PCR） was performed to detect the mRNA expression of neuroinflammation-related factors and genes in the NLRP3/Caspase-1/GSDMD pyroptosis pathway in the hippocampus. Western blot was used to detect the expression of postsynaptic density protein 95 （PSD95）， amyloid precursor protein （APP）， inflammatory factors including nuclear factor-κB （NF-κB）， phosphorylated NF-κB （p-NF-κB）， tumor necrosis factor-α （TNF-α）， interleukin-1β （IL-1β）， as well as pyroptosis pathway-related proteins including NLRP3， Caspase-1， GSDMD， and GSDMD-N. ResultsCompared with the control group， the model group exhibited significantly decreased learning and memory abilities （P<0.01）， reduced numbers of neurons in the hippocampal CA3 region and dendritic spines in the hippocampal CA1 region （P<0.01）， and significantly increased hippocampal mRNA expression levels of NLRP3， Caspase-1， GSDMD， NF-κB， TNF-α， IL-1β， and IL-18 （P<0.01）. Protein levels of PSD95 were markedly decreased， while the expression levels of NLRP3， Caspase-1， GSDMD， p-NF-κB/NF-κB， TNF-α， IL-1β， and APP were significantly elevated （P<0.01）. Compared with the model group， both the Donepezil and HLJDT groups showed significantly improved learning and memory abilities （P<0.05， P<0.01）， increased numbers of hippocampal neurons in the hippocampal CA3 region and dendritic spines in the hippocampal CA1 region （P<0.01）， and significantly decreased hippocampal mRNA expression levels of NLRP3， Caspase-1， GSDMD， NF-κB， TNF-α， IL-1β， and IL-18 （P<0.05， P<0.01）. Protein levels of NLRP3， Caspase-1， GSDMD， p-NF-κB/NF-κB， TNF-α， IL-1β， and APP were significantly downregulated， while PSD95 expression was significantly upregulated （P<0.05， P<0.01）. There was no statistically significant difference in GSDMD-N levels in the Donepezil group， while GSDMD-N expression was significantly decreased in the HLJDT group （P<0.05）. ConclusionThis study confirms that HLJDT can improve learning and memory abilities in APP/PS1 double transgenic mice， and attenuate neuronal loss and synaptic damage， possibly through inhibition of pyroptosis via the NLRP3/Caspase-1/GSDMD pathway.

Objective:To compare the efficacy of early versus delayed reconstruction of anterior cruciate ligament (ACL) ruptures under arthroscopy.Methods:A retrospective cohort study was conducted to analyze the clinical data of 260 young adults with ACL ruptures admitted to 940th Hospital of Joint Logistic Support Force of PLA from January 2022 to June 2024, including 171 males and 89 females, aged 18-45 years [(25.6±5.9)years]. Left knee was involved in 127 patients, while the right in 133 patients. All the patients underwent arthroscopic ACL reconstruction with autologous tendon grafts, of whom 130 patients were treated within 3 months after injury (early reconstruction group) but other 130 treated at 3 months after injury (delayed reconstruction group). The operative duration and intraoperative bleeding were compared between the two groups. The incidence of medial meniscus (MM) and lateral meniscus (LM) tears and the incidence of corresponding types of tears were recorded intraoperatively in the two groups. Tegner score and Lysholm score preoperatively, at 3 months postoperatively, and at the last follow-up were detected. Visual analogue scale (VAS) scores at 3 months postoperatively and at the last follow-up and postoperative complication rate were compared between the two groups.Results:All the patients were followed up for 6-15 months [(9.1±3.2)months]. There were no significant differences in operative duration or intraoperative bleeding between the two groups ( P>0.05). The incidence of MM tears in the early reconstruction group was 22.3% (29/130), lower than 34.6% (45/130) in the delayed reconstruction group ( P<0.05). There was no significant difference in the incidence of LM tears between the two groups ( P>0.05). The incidence of MM bucket-handle tears in the early reconstruction group was 2.3% (3/130), lower than 9.2% (12/130) in the delayed reconstruction group ( P<0.05), while no significant difference in the incidence of other types of meniscus tears was found between the two groups ( P>0.05). There were no significant differences in Tegner score or Lysholm score preoperatively between the two groups ( P>0.05). At 3 months postoperatively and at the last follow-up, the Tegner scores in the early reconstruction group were (7.4±1.3)points and (8.6±0.7)points, higher than (6.4±1.5)points and (7.9±0.6)points in the delayed reconstruction group and the Lysholm scores were (82.1±7.1)points and (90.7±3.8)points in the early reconstruction group, higher than (79.5±6.8)points and (86.3±4.0)points in the delayed reconstruction group ( P<0.01). There were no significant differences in VAS scores between the two groups at 3 months postoperatively or at the last follow-up ( P>0.05). The postoperative complication rate was 8.5% (11/130) in the early reconstruction group and 12.3% (16/130) in the delayed reconstruction group ( P>0.05). Conclusion:For young patients with ACL rupture, arthroscopic reconstruction within 3 months after injury can reduce the incidence of MM tear and bucket-handle tear and improve knee function without increasing the incidence of other complications when compared with delayed reconstruction at 3 months after injury.

Objective To investigate the epidemiological characteristics of knee osteoarthritis(KOA)among military personnel in plateau regions and to explore its risk factors.Methods From July 2023 to July 2024,a multi-stage stratified cluster random sampling method was employed to survey the prevalence of KOA and related risk factors among military personnel in the northwest plateau regions of China,covering different altitudes(1500-4500 m)and geographical areas(Gansu,Qinghai,Tibet,and Xinjiang).All study subjects were divided into KOA and non-KOA groups based on the presence or absence of KOA.Variables including age,gender,body mass index(BMI),education level,smoking status,military rank,military branch,service duration,regional altitude,annual average temperature,training duration,perceived training intensity,and history of knee injury were selected for univariate analyses between groups.Variables with P<0.05 in the univariate analyses were included in the binary multifactor logistic regression to identify risk factors for KOA.Results A total of 3000 questionnaires were distributed,and 2854 valid questionnaires were collected,with a response rate of 95.13%.The sample included 2584 males and 270 females,with 510 cases of KOA,resulting in a prevalence rate of 17.9%.Univariate analysis showed that there were statistically significant differences between KOA and non-KOA groups in terms of age,BMI,smoking status,military rank,military branch,service duration,regional altitude,annual average temperature,training duration,perceived training intensity,and history of knee injury(P<0.05).However,no significant differences were found in gender and education level(P>0.05).Binary multivariate logistic regression analysis revealed that older age(OR=1.382,P=0.017),higher BMI(P<0.01),smoking(OR=1.929,P<0.01),higher military rank(OR=1.485,P=0.007),being a member of the Armed Police(P<0.01),longer service duration(P<0.01),higher regional altitude(OR=1.459,P<0.01),lower annual average temperature(OR=1.188,P=0.001),longer training duration(P<0.01),higher perceived training intensity(OR=2.450,P<0.01),and history of knee injury(OR=2.768,P=0.002)were independent risk factors for KOA.Conclusions Older age,overweight/obesity,smoking,higher military rank,being a member of the Armed Police,longer service duration,higher altitude,cold climate,longer training duration,higher training intensity,and history of knee injury are independent risk factors for KOA among military personnel in the northwest plateau regions of China.

Objective:To compare the efficacy of early versus delayed reconstruction of anterior cruciate ligament (ACL) ruptures under arthroscopy.Methods:A retrospective cohort study was conducted to analyze the clinical data of 260 young adults with ACL ruptures admitted to 940th Hospital of Joint Logistic Support Force of PLA from January 2022 to June 2024, including 171 males and 89 females, aged 18-45 years [(25.6±5.9)years]. Left knee was involved in 127 patients, while the right in 133 patients. All the patients underwent arthroscopic ACL reconstruction with autologous tendon grafts, of whom 130 patients were treated within 3 months after injury (early reconstruction group) but other 130 treated at 3 months after injury (delayed reconstruction group). The operative duration and intraoperative bleeding were compared between the two groups. The incidence of medial meniscus (MM) and lateral meniscus (LM) tears and the incidence of corresponding types of tears were recorded intraoperatively in the two groups. Tegner score and Lysholm score preoperatively, at 3 months postoperatively, and at the last follow-up were detected. Visual analogue scale (VAS) scores at 3 months postoperatively and at the last follow-up and postoperative complication rate were compared between the two groups.Results:All the patients were followed up for 6-15 months [(9.1±3.2)months]. There were no significant differences in operative duration or intraoperative bleeding between the two groups ( P>0.05). The incidence of MM tears in the early reconstruction group was 22.3% (29/130), lower than 34.6% (45/130) in the delayed reconstruction group ( P<0.05). There was no significant difference in the incidence of LM tears between the two groups ( P>0.05). The incidence of MM bucket-handle tears in the early reconstruction group was 2.3% (3/130), lower than 9.2% (12/130) in the delayed reconstruction group ( P<0.05), while no significant difference in the incidence of other types of meniscus tears was found between the two groups ( P>0.05). There were no significant differences in Tegner score or Lysholm score preoperatively between the two groups ( P>0.05). At 3 months postoperatively and at the last follow-up, the Tegner scores in the early reconstruction group were (7.4±1.3)points and (8.6±0.7)points, higher than (6.4±1.5)points and (7.9±0.6)points in the delayed reconstruction group and the Lysholm scores were (82.1±7.1)points and (90.7±3.8)points in the early reconstruction group, higher than (79.5±6.8)points and (86.3±4.0)points in the delayed reconstruction group ( P<0.01). There were no significant differences in VAS scores between the two groups at 3 months postoperatively or at the last follow-up ( P>0.05). The postoperative complication rate was 8.5% (11/130) in the early reconstruction group and 12.3% (16/130) in the delayed reconstruction group ( P>0.05). Conclusion:For young patients with ACL rupture, arthroscopic reconstruction within 3 months after injury can reduce the incidence of MM tear and bucket-handle tear and improve knee function without increasing the incidence of other complications when compared with delayed reconstruction at 3 months after injury.

Objectives:To explore the relationship between insomnia symptoms and neuroticism in patients with COVID-19,and to explore the role of anxiety and psychological capital in the relationship.Methods:Totally 687 patients with COVID-19 were recruited from Shanghai Fangcang Hospital.The Athens Insomnia Scale(AIS),Eysenck Personality Questionnaire-Revised Short Scale for Chinese Neuroticism Subscale(EPQ-RSC-N),Self-Rat-ing Anxiety Scale(SAS)and Psychological Capital Questionnaire(PCQ)were used to measure insomnia symp-toms,neuroticism personality trait,anxiety symptoms and psychological capital levels.The deviation-corrected per-centile Bootstrap method was used to test the mediating effect,and the PROCESS program was used to test the moderated effect.Results:The detection rate of insomnia symptoms was 49.93％.The AIS scores were lower in male patients than in female patients(P＜0.01).The SAS scores partly mediated the relationship between neuroti-cism scores and AIS scores,with an effect size of 0.03,accounting for 18.29％of the total effect.With the im-provement of PCQ scores,the predictive effect of SAS scores on AIS scores gradually decreased(β=-0.01,t=-4.41,P＜0.001).Conclusions:Anxiety symptoms in patients with COVID-19 play a partial mediating role in the positive relationship between insomnia symptoms and neuroticism.The psychological capital moderates the relation-ship between insomnia and anxiety symptoms.

An increasing number of studies have been focused on the field of immune system in the central nervous system(CNS),as the viewpoint of CNS immune privilege being challenged.Among them,CNS boarder-associated macrophages(BAMs)play a prominent role in the regulation of brain homeostasis and related diseases.Unlike microglia located in the brain parenchyma,BAMs are a type of specialized macrophages located in the meninges(including dura,arachnoid,and leptomeninges),perivascular spaces,and choroid plexus.They are crucial for immune surveillance,cerebrospinal fluid drainage,antigen clearance,material exchange,and etc.Here,we reviewed a series of relevant studies on the origin and roles of BAMs in CNS,so as to broaden the understanding of the mechanisms of by which BAMs maintain the brain homeostasis,as well as provide novel insights into the treatment of CNS diseases including Alzheimer's disease.