Maze Experiment Research Articles

Alzheimer's Disease-Derived Outer Membrane Vesicles Exacerbate Cognitive Dysfunction, Modulate the Gut Microbiome, and Increase Neuroinflammation and Amyloid-β Production.

Although our understanding of the molecular biology of Alzheimer's disease (AD) continues to improve, the etiology of the disease, particularly the involvement of gut microbiota disturbances, remains a challenge. Outer membrane vesicles (OMVs) play a key role in central nervous system diseases, but the impact of OMVs on AD progression remains unclear. In this study, we hypothesized that AD-derived OMVs (OMVsAD) were a risk factor in AD pathology. To test our hypothesis, young APP/PS1 mice (AD mice) were given OMVsAD by gavage. Young AD mice were euthanized 120days after gavage to assess the intestinal barrier, gut microbiota diversity, mediators of neuroinflammation, glial markers, amyloid burden, and short-chain fatty acid (SCFA) levels. Our results showed that OMVsAD accelerated cognitive dysfunction after 120days of intragastric administration. Morris water maze experiment and new object recognition test showed that OMVsAD caused significantly poorer spatial ability learning and memory of the AD mice. We observed the OMVsAD-treated APP/PS1 mice display OMVs disrupting the intestinal barrier compared with controls of normal human-derived OMVs. Compared with the OMVsHC group, claudin-5 and ZO-1 related to the intestinal barrier were significantly downregulated in the OMVsAD group. The OMVsAD activate microglia in the cerebral cortex and hippocampus of AD mice, and the levels of IL-1β, IL-6, TNF-α, and NF-Κb were upregulated. We also found that OMVsAD increased Aβ production. 16S rRNA sequencing showed that OMVsAD negatively regulated the α- and β-diversity index of intestinal flora and reduced the levels of SCFA. OMVsAD may change the intestinal flora of young AD, damage the intestinal mucosa and blood-brain barrier, and accelerate AD neuropathological damage.

USP15 as a Potential Therapeutic Target in Cerebral Ischemia: Modulation of Ferroptosis and Cognitive Dysfunction via the Nrf2/GPX4 Axis in Mice.

This study aimed to investigate the role of ubiquitin-specific peptidase 15 (USP15) in ischemic cognitive dysfunction using a mouse model and a cerebral ischemia (CI) cell model, its impact on ferroptosis and the underlying mechanisms. Oxygen-glucose deprivation/reoxygenation (OGD/ R)-induced HT-22 cells were used to establish the CI cell model, and mice induced with CI were used as the animal model for ischemic cognitive dysfunction. Cell damage was evaluated using Cell Counting Kit-8 (CCK-8), flow cytometry (FCM), immunoblotting, and immunofluorescence assays. Cognitive dysfunction in the CI mice was assessed through water maze experiments. Ferroptosis was examined with an iron detection kit and immunoblotting, oxidative stress was evaluated using 2',7'-dichlorofluorescin diacetate (DCF) and enzyme-linked immunosorbent assay (ELISA), and mechanistic experiments were performed via immunoblotting. USP15 knockdown alleviated OGD/ R-induced damage in HT-22 cells. In vivo, USP15 depletion mitigated brain injury in middle cerebral artery occlusion (MCAO) mice and improved learning and memory function. The absence of USP15 reduced oxidative stress in MCAO mice and attenuated ferroptosis by activating nuclear factor erythroid 2-related factor 2 (Nrf2). Mechanistic investigations confirmed that USP15 depletion ameliorated cognitive impairment and ferroptosis through the activation of the Nrf2/ GPX4 axis. USP15 is associated with ferroptosis and cognitive dysfunction in mice and could serve as a potential therapeutic target in CI.

Effect of acupuncture on AMPK/ULK1 signaling pathway of hippocampus in chronic stress-induced depression rats

To observe the effect of manual acupuncture stimulation on changes of behavior and hippocampal signaling pathways of AMP-activated kinase (AMPK)/UNC-51-like kinase 1 (ULK1) in rats with chronic unpredictable mild stress (CUMS)-induced depression, so as to explore its molecular mechanism underlying improvement of depression. Thirty-two male SD rats were randomly divided into normal control, model, acupuncture and medication (fluoxetine) groups, with 8 rats in each group. The depression model was established by using CUMS (fasting, water depredation, restraint, swimming in cold water, crowding, stroboscope stimulation, and tail clipping, each of which was used once a week) for 6 weeks. Manual acupuncture stimulation was applied to "Baihui"(GV20) and "Yintang"(EX-HN3) for 10 min, once daily, 6 times a week for 6 weeks before every-day modeling. Rats of the medication group received gavage of fluoxetine (10 mg/kg) once a day for 6 weeks before every-day modeling. The percentage of sucrose preference, and the percentages of open arm times and open arm time in the elevated plus maze experiments were detected. The expression levels of AMPK, phosphorylated (p)-AMPK, ULK1, p-ULK1, mammalian target of rapamycin (mTOR) and p-mTOR proteins in the hippocampus tissue were detected by Western blot, and the expression of autophagy effecting protein (Beclin-1) and the selective autophagy receptors (p62) mRNA in the hippocampal tissue was detected using real-time fluorescence quantitative PCR, respectively. Compared with the normal group, the percentage of sucrose preference, percentage of times of entering the open arm and percentage of open arm time, the expression levels of p-AMPK /AMPK ratio, p-ULK1 /ULK1 ratio of proteins, and Beclin-1 mRNA were significantly decreased (P<0.01, P<0.05), and the expression levels of p-mTOR /mTOR ratio and p62 mRNA were significantly increased (P<0.01, P<0.05) in the model group. In comparison with the model group, the percentage of sucrose preference, percentage of open arm times and open arm time, the expression levels of p-AMPK /AMPK ratio, p-ULK1/ULK1 ratio of proteins, and Beclin-1 mRNA were significantly increased in both acupuncture and medication groups (P<0.01, P<0.05), while the expression levels of p-mTOR /mTOR ratio of proteins, and p62 mRNA were markedly decreased only in the medication group (P<0.05). Acupuncture treatment can alleviate depression-like behavior in CUMS rats, which may be related to its functions in up-regulating AMPK/ULK1 signaling pathway to induce cellular autophagy in the hippocampus.

The Influence of Strain and Sex on High Fat Diet-Associated Alterations of Dopamine Neurochemistry in Mice.

Objective: The objective of this study was to determine the influence of sex and strain on striatal and nucleus accumbens dopamine neurochemistry and dopamine-related behavior due to a high-saturated-fat diet (HFD). Methods: Male and female C57B6/J (B6J) and Balb/cJ (Balb/c) mice were randomly assigned to a control-fat diet (CFD) containing 10% kcal fat/g or a mineral-matched HFD containing 60% kcal fat/g for 12 weeks. Results: Intraperitoneal glucose tolerance testing (IPGTT) and elevated plus maze experiments (EPM) confirmed that an HFD produced marked blunting of glucose clearance and increased anxiety-like behavior, respectively, in male and female B6J mice. Electrically evoked dopamine release in the striatum and reuptake in the nucleus accumbens (NAc), as measured by ex vivo fast scan cyclic voltammetry, was reduced for HFD-fed B6J females. Impairment in glucose metabolism explained HFD-induced changes in dopamine neurochemistry for B6J males and, to a lesser extent, Balb/c males. The relative expressions of protein markers associated with the activation of microglia, ionized calcium binding adaptor molecule (Iba1) and cluster of differentiation molecule 11b (CD11b) in the striatum were increased due to an HFD for B6J males but were unchanged or decreased amongst HFD-fed Balb/c mice. Conclusions: Our findings demonstrate that strain and sex influence the insulin- and microglia-dependent mechanisms of alterations to dopamine neurochemistry and associated behavior due to an HFD.

Incremental structure building in the processing of ellipsis.

This article presents the results of two experiments conducted to examine how ellipsis sites are processed during the processing of backward sluicing, which is superficially similar to non-sluicing wh-filler-gap dependencies. Previous studies on long-distance wh-filler-gap dependencies established that the processing of these dependencies is sensitive to the syntactic structure of materials within the dependency: CP vs. NP. Results from two maze experiments show that backward sluicing processing is sensitive to the same structural factors, confirming that the same processing mechanism underlies both constructions. We suggest that an active search mechanism is operating at the core for these structures and with the interaction of the ellipsis-specific mechanism, e.g., a word-by-word copying mechanism, the parser builds antecedent structure within the ellipsis site incrementally during the processing of backward sluicing.

Preclinical monitoring of radiation-induced brain injury via GluCEST MRI and resting-state fMRI at 7T: an exploratory study on MRI-guided OAR avoidance.

To assess the value of glutamate chemical exchange saturation transfer (GluCEST) after whole-brain radiotherapy (WBRT) as an imaging marker of radiation-induced brain injury (RBI) and to preliminarily show the feasibility of multiparametric MRI-guided organ at risk (OAR) avoidance. Rats were divided into two groups: the control (CTRL) group (n = 9) and the RBI group (n = 9). The rats in the RBI group were irradiated with an X‑ray radiator and then subjected to awater maze experiment 4weeks later. In combination with high-performance liquid chromatography (HPLC), we evaluated the value of GluCEST applied to glutamate changes for RBI and investigated the effect of such changes on glutamatergic neuronal function. The average GluCEST values were markedly lower in the hippocampus and cerebral cortex. Positive correlations were observed between GluCEST values and regional homogeneity (ReHo) values in both the hippocampus and the cerebral cortex. HPLC showed apositive correlation with GluCEST values in the hippocampus. GluCEST values were positively correlated with spatial memory. GluCEST MRI provides avisual assessment of glutamate changes in RBI rats for monitoring OAR cognitive toxicity reactions and may be used as abiomarker of OAR avoidance as well as metabolism to facilitate monitoring and intervention in radiation damage that occurs after radiotherapy.

The Effect of a Caffeine and Nicotine Combination on Nicotine Withdrawal Syndrome in Mice.

Nicotine dependence is an important cause of excessive exposure to tobacco combustion compounds in most smokers. Nicotine replacement therapy is the main method to treat nicotine dependence, but it still has its shortcomings, such as the inability to mitigate withdrawal effects and limited applicability. It has been hypothesized that a combination of low-dose nicotine and caffeine could achieve the same psychological stimulation effect as a high dose of nicotine without causing nicotine withdrawal effects. To establish a model of nicotine dependence, male C57BL/6J mice were subcutaneously injected four times a day with nicotine (2 mg/kg) for 15 days and fed with water containing nicotine at the same time. They were randomly divided into four groups. After 24 h of withdrawal, different groups were injected with saline, nicotine (0.25 mg/kg or 0.1 mg/kg), or nicotine (0.1 mg/kg) and caffeine (20 mg/kg). Behavioral and physiological changes were evaluated by an assessment of physical signs, open field tests, elevated plus maze experiments, forced swimming tests, hot plate tests, and new-object-recognition tests. The changes in dopamine release in the prefrontal cortex (PFC) and ventral tegmental area (VTA) in the midbrain were analyzed using ELISA. The results showed that a combination of caffeine and nicotine could effectively relieve nicotine withdrawal syndrome, increase movement ability and pain thresholds, reduce anxiety and depression, enhance memory and cognitive ability, and increase the level of dopamine release in the PFC and VTA. Thus, caffeine combined with nicotine has potential as a stable and effective treatment option to help humans with smoking cessation.

Study on the Effects of Acupuncture with the "Yizhi Tiaoshen" Acupoint Formula on Blood Oxygen Metabolism and Neural Function in Key Brain Regions of AD Rats.

Exploring the effects of acupuncture at the "Yizhi Tiaoshen" acupoint on blood oxygen metabolism and neurological function changes in the brain regions of AD model rats. The AD model was replicated by intraperitoneal injection of D-galactose combined with bilateral hippocampal CA1 injection of Okadaic acid (OA). Thirty rats with successfully replicated model were selected through Morris water maze experiment and randomly divided into model group, donepezil hydrochloride group, and acupuncture group, with 10 rats in each group. After treatment, fNIRs were used to detect changes in Oxy Hb, Deoxy Hb, and Total Hb in the cerebral cortex of rats in each group, in order to evaluate the neurological function changes in key brain areas. The escape latency of the donepezil hydrochloride group and the acupuncture group was shortened, the number of crossings through the original platform increased, and the duration of stay in the quadrant where the original platform was located was prolonged. Based on fNIRs detection, the main differential channels of blood oxygen metabolism in AD rats were identified as 2-2 and 8-7, corresponding to the prefrontal and parietal lobes, respectively. The concentrations of Oxy Hb and Total Hb were significantly increased in both treatment groups, while the concentration of Deoxy Hb was significantly decreased. Acupuncture with the "Yizhi Tiaoshen" acupoint formula and donepezil hydrochloride can improve the learning and memory function of AD rats, and its mechanism may be related to improving blood oxygen metabolism in the prefrontal and parietal regions and protecting neuronal function.

Effects of parecoxib sodium on early cognitive impairment and inflammation levels in burned rats.

To study the effect of parecoxib sodium in alleviating inflammation in burned rats and restoring cognitive function in burned rats. 30 SPF grade SD rats were randomly divided into 6 groups: (1) Blank control group (Group C). (2) Sham surgery group (Group Sham). (3) Second-degree burn model (Group B). (4) Low-dose (1mg/kg/d) parecoxib sodium (Group L+B). (5) Medium-dose (10mg/kg/d) parecoxib sodium (Group M+B). (6) High-dose (20mg/kg/d) parecoxib sodium (Group H+B). ELISA measures inflammatory factor IL-2, IL-6, TNF-α and IFN-γ, cognitive function factor NSE, cortisol and S-100β. Combined with water maze and dark avoidance experiments to further verify the recovery of cognitive function in rats. The contents of IL-2, TNF-α and IL-6 in Group M+B were significantly lower than those in Group Sham (P<0.05), and the content of IFN-γ was significantly lower than that in Group Sham (P<0.05). The cognitive markers NSE, S-100β and cortisol levels in Group M+B were significantly higher than those in Group Sham at 2h, 1d, 5d and 10d after operation (P<0.05). In the Group M+B dark-avoidance experiment, the number of probes and errors were not significantly different than those in Group Sham and Group C (P>0.05), and the number of times Group M+B found a platform in the water maze experiment and crossed the platform was second only to Group B and Group C. Parecoxib sodium can effectively reduce inflammation in burn rats and promote cognitive recovery in burn rats, and the optimal dose of parecoxib sodium for burn rats is 10mg/kg.

Topical application of daphnetin hydrogel for traumatic brain injury.

Traumatic brain injury (TBI) causes neuronal cell damage and dysfunction. According to previous studies, daphnetin (Dap) has a protective effect in neurological injury. However, the in vivo bioavailability of daphnetin is not high. The purpose of this study was to determine whether administering daphnetin directly into the site of injury via a hydrogel drug carrier could improve its therapeutic impact. Tripolycerol monostearates / daphnetin (TM/Dap) hydrogels were prepared and characterised using water bath heating, scanning electron microscopy (SEM) and small animal in vivo imaging techniques. The TBI model was established using the Feeney free fall impact method. Using the Morris water maze test, the mNSS neurological deficit rating scale, haematoxylin-eosin staining, and liver and kidney function tests, the therapeutic benefit of TM/Dap and its toxic side effects were assessed. The therapeutic effects of TM/Dap were further investigated using wet and dry gravimetric methods, Evans blue staining, protein immunoblotting, immunofluorescence staining techniques and ELISA. The efficacy of the TM/Dap hydrogel in gradually releasing daphnetin in the context of traumatic brain damage was shown by both in vitro and in vivo tests. Behavioral experiments showed that the learning and spatial memory abilities of TM/Dap hydrogel treated mice were significantly improved in the water maze experiment. And TM/Dap hydrogel has high biosafety for organisms. The results of the therapeutic mechanism of action showed that TM/Dap hydrogel showed more significant efficacy in reducing the neuroinflammatory response caused by TNF-α, IL-6 and other factors, as well as promoting the recovery of post-traumatic neurological function. The use of hydrogel as a drug carrier for daphnetin showed more significant efficacy in reducing neuroinflammatory response, protecting nerve tissue and promoting post-traumatic neurological recovery compared with traditional drug delivery methods.

Honokiol relieves hippocampal neuronal damage in Alzheimer's disease by activating the SIRT3-mediated mitochondrial autophagy.

This work elucidated the effect of honokiol (HKL) on hippocampal neuronal mitochondrial function in Alzheimer's disease (AD). APP/PS1 mice were used as AD mice models and exposed to HKL and 3-TYP. Morris water maze experiment was performed to appraise cognitive performance of mice. Hippocampal Aβ+ plaque deposition and neuronal survival was evaluated by immunohistochemistry and Nissl staining. Hippocampal neurons were dissociated from C57BL/6 mouse embryos. Hippocampal neuronal AD model was constructed by Aβ oligomers induction and treated with HKL, CsA and 3-TYP. Neuronal viability and apoptosis were detected by cell counting kit-8 assay and TUNEL staining. mRFP-eGFP-LC3 assay, MitoSOX Red, dichlorodihydrofluorescein diacetate, and JC-1 staining were performed to monitor neuronal autophagosomes, mitochondrial reactive oxygen species (ROS), neuronal ROS, and mitochondrial membrane potential. Autophagy-related proteins were detected by Western blot. In AD mice, HKL improved cognitive function, relieved hippocampal Aβ1-42 plaque deposition, promoted hippocampal neuron survival, and activated hippocampal SIRT3 expression and mitochondrial autophagy. These effects of HKL on AD mice were abolished by 3-TYP treatment. In hippocampal neuronal AD model, HKL increased neuronal activity, attenuated neuronal apoptosis and Aβ aggregation, activated SIRT3 and mitochondrial autophagy, reduced mitochondrial and neuronal ROS, and elevated mitochondrial membrane potential. CsA treatment and 3-TYP treatment abrogated the protection of HKL on hippocampal neuronal AD model. The promotion of mitochondrial autophagy by HKL in hippocampal neuronal AD model was counteracted by 3-TYP. HKL activates SIRT3-mediated mitochondrial autophagy to mitigate hippocampal neuronal damage in AD. HKL may be effective in treating AD.

Alantolactone improves cognitive impairment in rats with Porphyromonas gingivalis infection by inhibiting neuroinflammation, oxidative stress, and reducing Aβ levels

Neuroinflammation caused by the chronic periodontal pathogen Porphyromonas gingivalis is growing regarded as as a key factor in the pathogenesis of Alzheimer’s disease (AD). Alantolactone (AL), a sesquiterpene lactone isolated from the root of Inula racemosa Hook. f, has been proven to provide various neuroprotective effects. However, whether AL can improve cognitive impairment caused by P. gingivalis infection remains unclear. In this research, a rat model of P. gingivalis infection was used to examine the neuroprotective benefits of AL. The results revealed that 6 weeks of AL treatment (50 and 100 mg/kg) shortened escape latency and increased the number of crossings over the platform location and time spent in the target quadrant of P. gingivalis-infected rats in the Morris water maze experiment. By activating the Nrf2/HO-1 pathway, AL suppressed malondialdehyde (MDA) levels and simultaneously increased the activity of total superoxide dismutase (T-SOD). Furthermore, AL lowered the presence of IL-6, IL-1β, and TNFα in the hippocampal and cortical tissues of P. gingivalis-infected rats by inhibiting astrocyte and microglial activation and NF-κB phosphorylation. AL also significantly reduced Aβ levels in the cortical and hippocampus tissues of rats infected with P. gingivalis. In conclusion, AL improved cognitive impairment in P. gingivalis-infected rats by inhibiting neuroinflammation, reducing Aβ1-42 level, and exerting antioxidative stress effects.

Modeling Fragile X Syndrome: Characterizing Fmr1 Gene Knockout Mice across Genotype, Behavior, and Morphology

ABSTRACT Objective: Fragile X syndrome (FXS) is a hereditary condition resulting from dynamic mutations in the Fmr1 gene, leading to reduced or absent fragile X mental retardation protein (FMRP). Although molecular genetic diagnostics for FXS have advanced, there is currently a lack of effective clinical treatment. Hence, identifying a suitable FXS animal model is crucial for FXS therapeutic studies. This study primarily aims to evaluate whether Fmr1 mice display aberrant behaviors similar to those observed in human FXS patients, aiming to validate their feasibility as a model for FXS. Research Design and Methods: Polymerase chain reaction and immunoblotting were employed to genotype Fmr1 knockout (KO) mice and wild-type (WT) mice. Using hematoxylin and eosin staining and Golgi staining, testicular and dendritic spine morphology in both animal groups was observed. The animals were subjected to audiogenic seizure (AGS) observation, evaluating their learning and memory levels using the water maze and light avoidance methods, while their exploratory behavior capacity was assessed using the open-field and autonomous activity experiments. Anxiety behavior was evaluated using the elevated plus maze. Results: WT mice produced a 500 bp DNA fragment, while KO mice yielded an 800 bp fragment. KO mice exhibited a lack of FMRP expression, notably increased dendritic spine length and density, and presented with macroorchidism. KO mice showed increased susceptibility to AGS. In the Morris water maze experiment, KO mice displayed significantly increased escape latency and platform crossings. The spatial search experiment revealed that KO mice spent significantly less time in the target quadrant compared to WT mice. The light-avoidance and platform experiments indicated a significant reduction in latency for KO mice but an increase in errors. In the open-field experiment, KO mice spent significantly more time and made more entries into the central zone compared to WT mice. KO mice exhibited increased total travel distance and speed. The elevated plus maze experiment showed that KO mice spent significantly more time, made more entries, and traveled further in the open area compared to WT mice. The autonomous activity experiment revealed that KO mice had significantly more activity counts than WT mice but fewer standing counts. Conclusions: Findings from genotype, protein expression spectrum, morphology, and behavioral results suggest that Fmr1 gene KO mice demonstrate phenotypes similar to those observed in human FXS, making them a potential model for future FXS research. These phenotypes are associated with the absence of FMRP expression.

Polygonatum polysaccharide ameliorates D-galactose-induced cognitive dysfunction in aging rats by inhibiting ferroptosis through activation of Nrf2

ContextAging is a major risk factor for various neurodegenerative diseases, and ferroptosis has been identified as an important mode of cell death during accelerated aging. As the main component of the edible plant YuZhu in China, Polygonatum polysaccharide (POP) is an important natural compound with anti-aging properties. ObjectiveTo evaluate the anti-aging effects of POP and the underlying molecular mechanisms involved and to evaluate the overall anti-aging effects of POP on cognitive impairment due to accelerated aging. Materials and methodsA D-galactose (D-gal)-induced accelerated aging rat model was established to evaluate the anti-aging effects of POP and the underlying molecular mechanisms involved. In turn, Morris water maze and open field experiments were used to evaluate the anti-aging effects of POP on cognitive impairment due to accelerated aging. ResultsThe mechanism by which POP affects nuclear factor E2-related factor 2 (Nrf2), an essential transcription factor, was confirmed. POP significantly improved d-gal-induced cognitive dysfunction in treated model rats, which exhibited reduced pathological changes in the hippocampus, reduced latency of the water maze platform, and increased exploration time in the central area in the open field experiment compared to those of untreated model rats. Furthermore, POP intervention downregulated ferroptosis-related proteins and upregulated Nrf2 expression, and selective inhibition of Nrf2 eliminated the ability of POP to reduce ferroptosis. ConclusionsPOP is a natural ingredient with therapeutic potential due to its ability to alleviate aging by activating Nrf2, inhibiting ferroptosis, and alleviating cognitive dysfunction.

Effect of Long-term Oral Administration of Different Dosages of Caffeine on Anesthetic Emerging Time

This paper aims to investigate the effect of prolonged oral ingestion of different doses of caffeine on anesthetic emergence time. In our experiment, eighteen male mice were selected and randomly divided into three groups of six mice, each according to the concentration of caffeine administered: a high-concentration caffeine group, a low-concentration caffeine group, and a blank control group. Mice were anesthetized with isoflurane and Zoletil 50, and the time of emergence was recorded for both anesthesia and the time of entry into anesthesia was recorded for Zoletil 50 anesthesia. Twenty-four hours after the anesthesia experiments, the mice were subjected to Morris water maze experiments, visual station experiments, hidden station experiments, and spatial exploration experiments. The results showed that both high-dose and low-dose coffee ig accelerated isoflurane and Zoletil 50 anesthesia emerging, with the high-dose being statistically more significant for the acceleration of anesthesia emerging. Prolonged oral coffee administration did not affect the time to enter anesthesia. Long-term oral coffee administration enhanced spatial exploration and spatial learning memory after anesthesia.

Effects of β-asarone on spatial learning and memory impairment by exhaustive exercise-induced fatigue: Role of NR-CaMKII-ERK/CREB signal in hippocampus of rats

ObjectiveIt is to investigate the effects of β-asarone on learning and memory, hippocampal morphology, synaptophysin (SYP) and postsynaptic density 95(PSD95) protein expression, N-methyl-D-aspartic acid receptor 2B (NR2B)- Ca2+/calmodulin (CaM)-dependent protein kinase II (CaMKII) - Extracellular signal-regulated kinase (ERK) / Cyclic-AMP response element binding protein (CREB) signal in hippocampus of rats with exhaustive exercise-induced fatigue. MethodsFifty Sprague-Dawley male rats were randomly divided into five groups: normal group, exercise group, exercise and β-asarone (2.5, 10, 40 mg/kg)–treated groups. The learning and memory in rats were tested by Morris water maze experiment. We measured the hippocampal morphology by Nissl staining. The levels of SYP, PSD95, NR2B, CaMKII, ERK1/2, CREB, p-NR2B, p-CaMKII, p-ERK1/2 and p-CREB expression were measured by western blot analysis. ResultsThe results demonstrated that β-asarone (10, 40 mg/kg) treatment significantly decreased the latency to find the platform, increased the time spent in the target quadrant and the number of crossing the platform of rats with exhaustive exercise-induced fatigue. β-asarone (10, 40 mg/kg) treatment increased the cell density in the hippocampus CA1 region, significantly up-regulated NR2B-CaMKII-ERK/CREB signal and improved the protein expression levels of SYP and PSD95 in hippocampus of rats with exhaustive exercise-induced fatigue. ConclusionsIt suggests that β-asarone could improve learning and memory of rats with exhaustive exercise-induced fatigue. The mechanism might be related to β-asarone protecting the morphology of hippocampus, increasing the protein expression levels of SYP and PSD95 and up-regulating NR2B-CaMKII-ERK/CREB signal in hippocampus of rats with exhaustive exercise-induced fatigue.

The effect of the AIM2 inflammasome in noise-induced cognitive dysfunction in rats

Objective: To explore the effect of the absent in melanoma 2 (AIM2) -mediated neuroinflammation in noise-induced cognitive dysfunction in rats. Methods: In April 2023, sixteen male Wistar rats were randomly divided into control group and noise group, with 8 rats in each group. The rats in the noise group were placed in 50 cm×50 cm×40 cm transparent boxes and exposed to 100 dB (A) white noise with a sound pressure level of 100 dB (A) (4 h/d for 30 d) . At the same time, rats in the control group were kept in similar boxes with environmental noise less than 60 dB (A) . After 30 days of noise exposure, the Morris water maze experiment was applied to test the learning and memory abilities of the rats; the pathological morphology of hippocampal tissues was observed by Hematoxylin-Eosin (HE) staining. Western blot was used to detect the protein expression levels of AIM2, cysteinyl aspartate specific proteinase-1 (caspase-1) , apoptosis-associated speck-like protein (ASC) , interleukin-1β (IL-1β) , IL-18, ionic calcium-binding articulation molecule-1 (Iba-1) , and glial fibrillary acidic protein (GFAP) . The expression of both Iba-1 and GFAP in hippocampal tissue was assessed by immunohistochemical staining. The co-localization of AIM2 with Iba-1 or GFAP was determined by immunofluorescence double staining. Results: Compared with the control group, the escape latency of rats in the noise group was increased by 16.29 s, 17.71 s, and 20.26 s on days 3, 4, and 5, respectively. On day 6, the noise-exposed rats spent shorter time in the target quadrant and had fewer times in crossing the platform[ (7.25±2.27) s and (1.13±0.64) times] than the control group[ (15.64±3.99) s and (4.25±2.12) times] (P<0.05) . After noise exposure, hippocampal neurons of rats displayed marked nuclear hyperchromatic and pyknosis phenomenon. The noise-exposed rats had higher numbers of both microglia and astrocytes (27.00±2.65 and 43.33±5.51) in the DG area of the hippocampus relative to the control group (14.67±3.06 and 20.00±4.58) (P<0.05) . Moreover, the glial cells in the noise group had larger cell cytosol with more and thicker branches. The protein expression levels of inflammatory cytokines Cleaved-IL-1β and Cleaved-IL-18 in the hippocampus of rats in the noise group (1.55±0.19 and 1.74±0.12) were significantly higher than the control group (1.00±0.11 and 1.00±0.13) (P<0.05) . After noise exposure, the protein expression levels of AIM2, Cleaved-Caspase-1 and ASC (1.19±0.09, 1.34±0.07 and 1.14±0.01) were higher than the control group (1.00±0.07, 1.00±0.14 and 1.00±0.06) and differences between the two groups were statistically significant (P<0.05) . A significant increase in the number of cells co-localizing AIM2 with Iba-1 or GFAP in the noise group (28.67±4.04 and 40.67±5.13) compared with the control group (15.67±4.04 and 17.67±3.79) , and statistically significant differences were observed between the two groups (P<0.05) . Conclusion: Noise exposure may activate the AIM2 inflammasome in hippocampal glial cells of rats, releasing excessive inflammatory cytokines and causing neuroinflammation that damages neurons.

The regulation of BAI1 in astrocytes through the STAT3/EZH2 axis relieves neuronal apoptosis in rats with Alzheimer’s disease

Alzheimer’s disease (AD) is a common neurodegenerative disease. Previous studies have identified the critical role of astrocytes in the progression of AD. The focus of this study revolves around clarifying the regulatory mechanism of the STAT3/EZH2/BAI1 axis in astrocytes in AD. We successfully developed a rat model of AD, and measured the learning and cognitive ability of the rats by Morris water maze experiment. HE and Nissl’s staining were used for histomorphological identification of the rat hippocampus. Meanwhile, immunofluorescence and immunohistochemistry were used to detect astrocyte activation and brain-specific angiogenesis inhibitor-1 (BAI1) expression in rat hippocampal tissue, respectively. The role of STAT3/EZH2/BAI1 regulating axis in astrocyte activation and neuronal cell apoptosis was verified by establishing the co-culture system of astrocytes and neuronal cells in vitro. Western Blot (WB) was used to detect the expression of associated proteins, and enzyme-linked immunosorbent assay (ELISA) was used to detect astrocyte neurotrophic factor secretion. Hochest/PI staining and flow cytometry were used to observe neuronal apoptosis. Compared with the sham group, AD rats showed significantly decreased cognitive and learning abilities, noticeable hippocampal tissue damage, and significantly low levels of BAI1 expression. In in vitro models, BAI1 was found to inhibit astrocyte activation and enhance the secretion of neurotrophins, resulting in decrease of neurone apoptosis. The regulation of BAI1 by the STAT3/EZH2 axis was shown to affect astrocyte activation and neuronal cell apoptosis. In conclusion, this study represents the pioneering discovery that regulated by the STAT3/EZH2 axis, BAI1 suppresses astrocyte activation, thus reducing neuronal apoptosis.

Exploring the Impact of Preoperative Sleep Fragmentation on Cognitive Function in Mice: The Role of Microglial Activation and Iron Metabolism

Background. Perioperative neurocognitive disorders (PND) are a significant concern, particularly for aged individuals. Sleep fragmentation (SF), a common condition in older adults, is considered a risk factor for PND. The present study explored the impact of SF on cognitive function and its association with microglial activation and iron metabolism. Methods. Adult and aged C57BL/6J mice were subjected to tibial fracture surgery (TFS) and varying durations of SF. Cognitive function was assessed using the Morris water maze and fear conditioning experiments. Microglial activation was evaluated by measuring CD68 protein expression and inflammatory cytokine levels. Iron metabolism and ferroptosis-related proteins were also examined. Results. SF significantly impacted spatial memory and conditioned fear responses in mice, with aged mice showing greater susceptibility. Microglial activation, indicated by changes in CD68 protein expression and inflammatory cytokine levels, was observed in mice exposed to SF. Alterations in iron metabolism, as evidenced by changes in hippocampal iron content and expression of ferroptosis-related proteins, were also observed in these mice. Conclusion. SF can lead to significant cognitive impairment, particularly in aged mice, likely mediated through microglial activation and dysregulated iron metabolism. These findings provide novel insights into the pathogenesis of PND and suggest potential targets for intervention. Significance. This study illuminates the complex interactions between SF, microglial activation, and cognitive function. It highlights the importance of sleep quality for cognitive health in older adults and points to potential therapeutic strategies for preventing PND, including targeting microglial activation and iron metabolism.

The impact of Nrf2 knockout on the neuroprotective effects of dexmedetomidine in a mice model of cognitive impairment

The nuclear factor erythroid 2-related factor 2 (Nrf2) signalling pathway represents a crucial intrinsic protective system against oxidative stress and inflammation and plays a significant role in various neurological disorders. However, the effect of Nrf2 signalling on the regulation of cognitive impairment remains unknown. Dexmedetomidine (DEX) has neuroprotective effects and can ameliorate lipopolysaccharide (LPS)-induced cognitive dysfunction. Our objective was to observe whether Nrf2 knockout influences the efficacy of DEX in improving cognitive impairment and to attempt to understand its underlying mechanisms. An LPS-induced cognitive dysfunction model in wild-type and Nrf2 knockout mice (Institute of Cancer Research background; male; 8–12 weeks) was used to observe the impact of DEX on cognitive dysfunction. LPS was intraperitoneally injected, followed by novel object recognition and morris water maze experiments 24 h later. Hippocampal tissues were collected for histopathological and molecular analyses. Our research findings suggest that DEX enhances the expression of NQO1, HO-1, PSD95, and SYP proteins in hippocampal tissue, inhibits microglial proliferation, reduces pro-inflammatory cytokines IL-1β and TNF-ɑ, increases anti-inflammatory cytokine IL-10, and improves dendritic spine density, thereby alleviating cognitive dysfunction induced by LPS. However, the knockout of the Nrf2 gene negated the aforementioned effects of DEX. In conclusion, DEX alleviates cognitive deficits induced by LPS through mechanisms of anti-oxidative stress and anti-inflammation, as well as by increasing synaptic protein expression and dendritic spine density. However, the knockout of the Nrf2 gene reversed the effects of DEX. The Nrf2 signaling pathway plays a crucial role in the mitigation of LPS-induced cognitive impairment by DEX.