Spatial Learning Ability Research Articles

Minocycline‐Loaded Cerium Oxide Nanoparticles for the Enhanced Treatment of Intracerebral Hemorrhage

AbstractInflammatory responses and neuronal ferroptosis, which are associated with abnormal accumulation of reactive oxygen species (ROS), exert crucial damaging effects on the brain after intracerebral hemorrhage (ICH). In this study, minocycline (MC)‐loaded cerium oxide nanoparticles (CeO2‐MC) are constructed for combined ICH treatment. Ultra‐small CeO2 (≈5 nm) synthesized via a high‐temperature approach exhibits powerful free‐radical scavenging and iron‐chelating abilities. In vitro experiments demonstrated that CeO2‐MC effectively attenuated the ROS levels in mouse microglial cells and neurons following oxyhemoglobin stimulation. In addition, CeO2‐MC exhibits iron chelation properties and stabilizes the mitochondrial membrane potential, thereby promoting anti‐inflammatory responses and preventing neuronal ferroptosis. In an intracerebral hemorrhage (ICH) mouse model, CeO2‐MC exhibited robust free radical scavenging capabilities and demonstrated the ability to preserve mitochondrial morphology and function, mitigate brain edema, and maintain blood–brain barrier integrity by inhibiting neuroinflammation and ferroptosis. Neurobehavioral tests demonstrated that CeO2‐MC significantly ameliorated spatial learning ability and sensorimotor function after ICH. Consequently, a general strategy using CeO2 nanoparticles to augment the therapeutic efficacy of MC highlights a new perspective for the in‐depth treatment of ICH.

Hypoxia preconditioning increases Notch1 activity by regulating DNA methylation in vitro and in vivo.

Our previous research has demonstrated that hypoxic preconditioning (HPC) can improve spatial learning and memory abilities in adult mice. Adult hippocampal neurogenesis has been associated with learning and memory. The Neurogenic locus notch homolog protein (Notch) was involved in adult hippocampal neurogenesis, as well as in learning and memory. It is currently unclear whether the Notch pathway regulates hippocampal neuroregeneration by modifying the DNA methylation status of the Notch gene following HPC. The HPC animal model and cell model were established through repeated hypoxia exposure using mice and the mouse hippocampal neuronal cell line HT22. Step-down test was conducted on HPC mice. Real-time PCR and Western blot analysis were used to assess the mRNA and protein expression levels of Notch1 and hairy and enhancer of split1 (HES1). The presence of BrdU-positive cells and Notch1 expression in the hippocampal dental gyrus (DG) were examined with confocal microscopy. The methylation status of the Notch1 was analyzed using methylation-specific PCR (MS-PCR). HT22 cells were employed to elucidate the impact of HPC on Notch1 in vitro. HPC significantly improved the step-down test performance of mice with elevated levels of mRNA and protein expression of Notch1 and HES1 (P < 0.05). The intensities of the Notch1 signal in the control group, the H group and the HPC group were 2.62 ± 0.57 × 107, 2.87 ± 0.84 × 107, and 3.32 ± 0.14 × 107, respectively, and the number of BrdU (+) cells in the hippocampal DG were 1.83 ± 0.54, 3.71 ± 0.64, and 7.29 ± 0.68 respectively. Compared with that in C and H group, the intensity of the Notch1 signal and the number of BrdU (+) cells increased significantly in HPC group (P < 0.05). The methylation levels of the Notch1 promoter 0.82 ± 0.03, 0.65 ± 0.03, and 0.60 ± 0.02 in the C, H, and HPC groups, respectively. The methylation levels of Notch1 decreased significantly (P < 0.05). The effect of HPC on HT22 cells exhibited similarities to that observed in the hippocampus. HPC may confer neuroprotection by activating the Notch1 signaling pathway and regulating its methylation level, resulting in the regeneration of hippocampal neurons.

Function and mechanism exploring of icariin in schizophrenia through network pharmacology

This study aims to explore the therapeutic effect and possible mechanisms of icariin in schizophrenia. SD rats were divided into five groups, a control group, a MK801-induced schizophrenia model group, and three icariin treatment groups, with twelve rats in each group. Morris water maze and open field were used to observe the spatial learning and memory ability of rats. Compared with the control group, rats in the MK801-induced model group showed an increase in stereotypic behavior score, distance of spontaneous activities, escape latency, malondialdehyde (MDA) content, and IL-6, IL-1β, TNF-α expression, but a decrease in platform crossing times and superoxide dismutase (SOD) activity (P < 0.05). Furthermore, all the above changes of the model group were reversed after icariin treatment in a dose-dependent manner (P < 0.05). Network pharmacology found that icariin can exert anti-schizophrenic effects through some signaling pathways, such as relaxin, estrogen, and TNF signaling pathways. MAPK1, MAPK3, FOS, RELA, TNF, and JUN were the key targets of icariin on schizophrenia, and their expression was detected in animal models, which was consistent with the predicted results of network pharmacology. Icariin treatment may improve the spatial learning and memory ability of schizophrenic rats through TNF signaling pathway.

Total ginsenosides decrease Aβ production through activating PPARγ

IntroductionTotal ginsenosides (TG), the major active constituents of ginseng, have been proven to be beneficial in treatment of Alzheimer’s disease (AD). However, the underlying mechanism of TG remains unclear. MethodsAPP/PS1 mice and N2a/APP695 cells were used as in vivo and in vitro model, respectively. Morris water maze (MWM) was used to investigate behavioral changes of mice; neuronal pathological changes were assessed by hematoxylin and eosin (H&E) and nissl staining; immunofluorescence staining was used to examine amyloid beta (Aβ) deposition; Western blotting and quantitative real-time polymerase chain reaction (qRT-PCR) were used to examine the expression of relative amyloidogenic genes and proteins. Moreover, the antagonist of PPARγ, GW9662, was used to determine whether the effects of TG on Aβ production were associated with PPARγ activity. ResultsTG treatment increased the spatial learning and memory abilities of APP/PS1 mice while decreasing the Aβ accumulation in the cortex and hippocampus. In N2a/APP695 cells, TG treatment attenuated the secretion of Aβ1–40 and Aβ1–42 acting as an PPARγ agonist by inhibiting the translocation of NF-κB p65. Additionally, TG treatment also decreased the expression of amyloidogenic pathway related gene BACE1, PS1 and PS2. ConclusionsTG treatment reduced the production of Aβ both in vivo and in vitro. Activating PPARγ might be a potential therapeutic target of TG in facilitating Aβ clearance and ameliorating cognitive deficiency in APP/PS1 mice.

Doxycycline cotherapy with albendazole relieves neural function damage in C57BL/6 and BALB/c mice infected with Angiostrongylus cantonensis

BackgroundWe investigated the effects of combination therapy albendazole and doxycycline in Angiostrongylus cantonensis-infected mice during early and late treatment. Materials and methodsC57BL/6 and BALB/c mice were divided into five groups: (i) uninfected, (ii) infected with A. cantonensis, (iii) infected + 10 mg/kg albendazole, (iv) infected + 25mg/kg doxycycline, and (v) infected + 10 mg/kg albendazole + 25 mg/kg doxycycline. We administered drugs in both early treatments started at 7-day post infections (dpi) and late treatments (14 dpi) to A. cantonensis-infected C57BL/6 and BALB/c mice. To assess the impact of these treatments, we employed the Morris water maze test to evaluate spatial learning and memory abilities, and the rotarod test to measure motor coordination and balance in C57BL/6 mice. Additionally, we monitored the expression of the cytokine IL-33 and GFAP in the brain of these mice using western blot analysis. ResultsIn this study, A. cantonensis infection was observed to cause extensive cerebral angiostrongyliasis in C57BL/6 mice. This condition significantly affected their spatial learning and memory abilities, as assessed by the Morris water maze test, as well as their motor coordination, which was evaluated using the rotarod test. Early treatment with albendazole led to favorable recovery outcomes. Both C57BL/6 and BALB/c mice express IL-33 and GFAP after co-therapy. The differences of levels and patterns of IL-33 and GFAP expression in mice may be influenced by the balance between pro-inflammatory and anti-inflammatory signals within the immune system. ConclusionsCombination therapy with anthelmintics and antibiotics in the early stage of A. cantonensis infection, in C57BL/6 and BALB/c mice resulted in the death of parasites in the brain and reduced the subsequent neural function damage and slowed brain damage and neurobehavior impairment. This study suggests a more effective and novel treatment, and drug delivery method for brain lesions that can decrease the neurological damage of angiostrongyliasis patients.

Tianma-Gouteng pair ameliorates the cognitive deficits on two transgenic mouse models of Alzheimer's disease

Ethnopharmacological relevanceAlzheimer's disease (AD) is a progressive neurodegenerative disease. Tianma-Gouteng Pair (TGP), commonly prescribed as a pair-herbs, can be found in many Chinese medicine formulae to treat brain diseases. However, the neuroprotective effects and molecular mechanisms of TGP remained unexplored. Aim of the studyThis study investigated the difference between the TgCRND8 and 5 × FAD transgenic mice, the anti-AD effects of TGP, and underlying molecular mechanisms of TGP against AD through the two mouse models. MethodsBriefly, three-month-old TgCRND8 and 5 × FAD mice were orally administered with TGP for 4 and 6 months, respectively. Behavioral tests were carried out to determine the neuropsychological functions. Moreover, immunofluorescence and western blotting assays were undertaken to reveal the molecular mechanisms of TGP. ResultsAlthough TgCRND8 and 5 × FAD mice had different beta-amyloid (Aβ) burdens, neuroinflammation status, and cognition impairments, TGP exerted neuroprotective effects against AD in the two models. In detail, behavioral tests revealed that TGP treatment markedly ameliorated the anxiety-like behavior, attenuated the recognition memory deficits, and increased the spatial learning ability as well as the reference memory of TgCRND8 and 5 × FAD mice. Moreover, TGP treatment could regulate the beta-amyloid precursor protein (APP) processing by inhibiting the Aβ production enzymes such as β- and γ-secretases and activating Aβ degrading enzyme to reduce Aβ accumulation. In addition, TGP reduced the Aβ42 level, the ratio of Aβ42/Αβ40, Aβ accumulation, and tau hyperphosphorylation in both the 5 × FAD and TgCRND8 mouse models. Furthermore, TGP ameliorated neuroinflammation by decreasing the densities of activated microglia and astrocytes, and inhibiting the production of inflammatory cytokines. TGP upregulated the SIRT1 and AMPK, and downregulated sterol response element binding protein 2 (SREBP2) in the brain of TgCRND8 mice and deactivation of the EPhA4 and c-Abl in the brain tissues of 5 × FAD mice. ConclusionOur experiments for the first time revealed the neuroprotective effects and molecular mechanism of TGP on 5 × FAD and TgCRND8 transgenic mouse models of different AD stages. TGP decreased the level of Aβ aggregates, improved the tauopathy, and reduced the neuroinflammation by regulation of the SIRT1/AMPK/SREBP2 axis and deactivation of EPhA4/c-Abl signaling pathway in the brains of TgCRND8 and 5 × FAD mice, respectively. All these findings unequivocally confirmed that the TGP would be promising in developing into an anti-AD therapeutic pharmaceutical.

Remimazolam Attenuates LPS-Derived Cognitive Dysfunction via Subdiaphragmatic Vagus Nerve Target α7nAChR-Mediated Nrf2/HO-1 Signal Pathway.

Sepsis-induced neuroinflammation is significantly associated with sepsis-related brain dysfunction. Remimazolam is a novel ultra-short-acting benzodiazepine anesthetic with multiple organ protective effects. However, it is unknown whether remimazolam can ameliorate LPS-induced brain impairment. In this study, Lipopolysaccharide (5mg/kg, LPS) severely impaired Sprague-Dawley rats spatial learning ability, memory, and cognitive function. However, remimazolam treatment showed a protective effect on LPS-induced cognitive dysfunction. Remimazolam partly reversed LPS-induced splenomegaly, decreased serum cytokine expression, suppressed hippocampal M1 microglial activation, and mitigated oxidative stress injury and neuroinflammation. Electroacupuncture (EA) or PNU282987 treatment improved LPS-induced cognitive dysfunction and also significantly inhibited neuroinflammation and systemic inflammation. However, MLA, ML385, or subdiaphragmatic vagus nerve (SDV) treatment abolished the protective effects of remimazolam. Further mechanistic studies showed that remimazolam induces protective effects by activating subdiaphragmatic vagus nerve target α7nAChR-mediated Nrf2/HO-1 signaling pathway. These results demonstrate that remimazolam can up-regulate α7nAChR, Cyto-Nrf2, HO-1, and cognitive-related (CREB, BDNF, PSD95) protein expressions, suppress M1 microglia, ameliorate neuroinflammation or systemic inflammation, and reverse cognitive dysfunction. Therefore, this study provides insight into a new therapeutic target for the treatment of sepsis-induced cerebral dysfunction.

Transcriptomic analysis to identify genes associated with hypothalamus vulnerability in aging mice with cognitive decline

The normal aging process is accompanied by cognitive decline, and previous studies have indicated the crucial role of the hypothalamus in regulating both aging and cognition. However, the precise molecular mechanism underlying this relationship remains unclear. Therefore, this present study aimed to identify potential predictors of cognitive decline associated with aging specifically within the hypothalamus. To achieve this, we employed Morris water maze (MWM) testing to assess learning and memory differences between young and aged mice. Additionally, transcriptome sequencing was conducted on the hypothalamus of young and aged mice to identify potential genes. Subsequently, GO and KEGG analyses were performed to investigate the functions of differentially expressed genes (DEGs) and their associated biological pathways. Finally, the results obtained from sequencing analysis were further validated using qRT-PCR. Notably, MWM testing revealed a significant decrease in spatial learning and memory ability among aged mice. According to KEGG analysis, the DEGs primarily encompassed various biochemical signaling pathways related to immune system (e.g., C3; C4b; Ccl2; Ccl7; Cebpb; Clec7a; Col3a1; Cxcl10; Cxcl2; Fosb; Fosl1; Gbp5; H2-Ab1; Hspa1a; Hspa1b; Icam1; Il1b; Itga5; Itgax; Lilrb4a; Plaur; Ptprc; Serpine1; Tnfrsf10b; Tnfsf10), neurodegenerative disease (e.g., Atp2a1; Creb5; Fzd10; Hspa1a; Hspa1b; Il1b; Kcnj10; Nxf3; Slc6a3; Tubb6; Uba1y; Wnt9b), nervous system function (e.g., Chrna4; Chrna6; Creb5; Slc6a3),and aging (e.g., Creb5; Hspa1a; Hspa1b) among others. These identified genes may serve as potential predictors for cognitive function in elderly individuals and will provide a crucial foundation for further exploration into the underlying molecular mechanisms.

Electroacupuncture Enhances the Functional Connectivity of Limbic System to Neocortex in the 5xFAD Mouse Model of Alzheimer's Disease

Our previous study revealed that acupuncture may exhibit therapeutic effects on Alzheimer's disease (AD) through the activation of metabolism in memory-related brain regions. However, the underlying functional mechanism remains poorly understood and warrants further investigation. In this study, we used resting-state functional magnetic resonance imaging (rsfMRI) to explore the potential effect of electroacupuncture (EA) on the 5xFAD mouse model of AD. We found that the EA group exhibited significant improvements in the number of platforms crossed and the time spent in the target quadrant when compared with the Model group (p < 0.05). The functional connectivity (FC) of left hippocampus (Hip) was enhanced significantly among 12 regions of interest (ROIs) in the EA group (p < 0.05). Based on the left Hip as the seed point, the rsfMRI analysis of the entire brain revealed increased FC between the limbic system and the neocortex in the 5xFAD mice after EA treatment. Additionally, the expression of amyloid-β(Aβ) protein and deposition in the Hip showed a downward trend in the EA group compared to the Model group (p < 0.05). In conclusion, our findings indicate that EA treatment can improve the learning and memory abilities and inhibit the expression of Aβ protein and deposition of 5xFAD mice. This improvement may be attributed to the enhancement of the resting-state functional activity and connectivity within the limbic-neocortical neural circuit, which are crucial for cognition, motor function, as well as spatial learning and memory abilities in AD mice.

Aerobic exercise attenuates LPS-induced cognitive dysfunction by reducing oxidative stress, glial activation, and neuroinflammation

Physical activity has been considered an important non-medication intervention in preserving mnemonic processes during aging. However, how aerobic exercise promotes such benefits for human health remains unclear. In this study, we aimed to explore the neuroprotective and anti-inflammatory effects of aerobic exercise against lipopolysaccharide (LPS)-induced amnesic C57BL/6J mice and BV-2 microglial cell models. In the in vivo experiment, the aerobic exercise training groups were allowed to run on a motorized treadmill 5 days/week for 4 weeks at a speed of 10 rpm/min, with LPS (0.1 mg/kg) intraperitoneally injected once a week for 4 weeks. We found that aerobic exercise ameliorated memory impairment and cognitive deficits among the amnesic mice. Correspondingly, aerobic exercise significantly increased the protein expressions of FNDC5, which activates target neuroprotective markers BDNF and CREB, and antioxidant markers Nrf2/HO-1, leading to inhibiting microglial-mediated neuroinflammation and reduced the expression of BACE-1 in the hippocampus and cerebral cortex of amnesic mice. We estimated that aerobic exercise inhibited neuroinflammation in part through the action of FNDC5/irisin on microglial cells. Therefore, we explored the anti-inflammatory effects of irisin on LPS-stimulated BV-2 microglial cells. In the in vitro experiment, irisin treatment blocked NF-κB/MAPK/IRF3 signaling activation concomitantly with the significantly lowered levels of the LPS-induced iNOS and COX-2 elevations and promotes the Nrf2/HO-1 expression in the LPS-stimulated BV-2 microglial cells. Together, our findings suggest that aerobic exercise can improve the spatial learning ability and cognitive functions of LPS-treated mice by inhibiting microglia-mediated neuroinflammation through its effect on the expression of BDNF/FNDC5/irisin.

Remote Ischemic Post-conditioning Reduces Cognitive Impairment in Rats Following Subarachnoid Hemorrhage: Possible Involvement in STAT3/STAT5 Phosphorylation and Th17/Treg Cell Homeostasis.

The inflammatory response following subarachnoid hemorrhage (SAH) may lead to Early Brain Injury and subsequently contribute to poor prognosis such as cognitive impairment in patients. Currently, there is a lack of effective strategies for SAH to ameliorate inflammation and improve cognitive impairment in clinical. This study aims to examine the inhibitory impact of remote ischemic post-conditioning (RIPostC) on the body's inflammatory response by regulating Th17/Treg cell homeostasis after SAH. The ultimate goal is to search for potential early treatment targets for SAH. The rat SAH models were made by intravascular puncture of the internal carotid artery. The intervention of RIPostC was administered for three consecutive days immediately after successful modeling. Behavioral experiments including the Morris water maze and Y-maze tests were conducted to assess cognitive functions such as spatial memory, working memory, and learning abilities 2weeks after successful modeling. The ratio of Th17 cells and Treg cells in the blood was detected using flow cytometry. Immunofluorescence was used to observe the infiltration of neutrophils into the brain. Signal transducers and activators of transcription 5 (STAT5) and signal transducers and activators of transcription 3 (STAT3) phosphorylation levels, receptor-related orphan receptor gamma-t (RORγt), and forkhead box protein P3 (Foxp3) levels were detected by Western blot. The levels of anti-inflammatory factors (IL-2, IL-10, IL-5, etc.) and pro-inflammatory factors (IL-6, IL-17, IL-18, TNF-α, IL-14, etc.) in blood were detected using Luminex Liquid Suspension Chip Assay. RIPostC significantly improved the cognitive impairment caused by SAH in rats. The results showed that infiltration of Th17 cells and neutrophils into brain tissue increased after SAH, leading to the release of pro-inflammatory factors (IL-6, IL-17, IL-18, and TNF-α). This response can be inhibited by RIPostC. Additionally, RIPostC facilitates the transfer of Treg from blood to the brain and triggers the release of anti-inflammatory (IL-2, IL-10, and IL-5) factors to suppress the inflammation following SAH. Finally, it was found that RIPostC increased the phosphorylation of STAT5 while decreasing the phosphorylation of STAT3. RIPostC reduces inflammation after SAH by partially balancing Th17/Treg cell homeostasis, which may be related to downregulation of STAT3 and upregulation of STAT5 phosphorylation, which ultimately alleviates cognitive impairment in rats. Targeting Th17/Treg cell homeostasis may be a promising strategy for early SAH treatment.

Enriched oxygen improves age-related cognitive impairment through enhancing autophagy.

Age-related cognitive impairment represents a significant health concern, with the understanding of its underlying mechanisms and potential interventions being of paramount importance. This study aimed to investigate the effects of hyperbaric oxygen therapy (HBOT) on cognitive function and neuronal integrity in aged (22-month-old) C57BL/6 mice. Male mice were exposed to HBOT for 2 weeks, and spatial learning and memory abilities were assessed using the Morris water maze. We employed transcriptome sequencing and Gene Ontology (GO) term enrichment analysis to examine the effects of HBOT on gene expression profiles, with particular attention given to synapse-related genes. Our data indicated a significant upregulation of postsynapse organization, synapse organization, and axonogenesis GO terms, likely contributing to improved cognitive performance. Moreover, the hyperphosphorylation of tau, a hallmark of many neurodegenerative diseases, was significantly reduced in the HBO-treated group, both in vivo and in vitro. Transmission electron microscopy revealed significant ultrastructural alterations in the hippocampus of the HBOT group, including an increase in the number of synapses and the size of the active zone, a reduction in demyelinated lesions, and a decreased number of "PANTHOS." Furthermore, Western blot analyses confirmed the upregulation of PSD95, BDNF, and Syn proteins, suggesting enhanced synaptic plasticity and neurotrophic support. Moreover, HBOT increased autophagy, as evidenced by the elevated levels of Beclin-1 and LC3 proteins and the reduced level of p62 protein. Finally, we demonstrated that HBOT activated the AMPK-mTOR signaling pathway, a critical regulator of autophagy. Notably, our findings provide novel insights into the mechanisms by which HBOT ameliorates age-related cognitive impairment, suggesting the potential therapeutic value of this approach.

Sevoflurane postconditioning alleviates hypoxic-ischemic brain damage in rats by inhibiting the endoplasmic reticulum stress PERK/ATF4/CHOP pathway

Hypoxic-ischemic brain damage (HIBD) frequently induces cognitive impairments. Investigating the role of sevoflurane postconditioning (SPC) in HIBD, we conducted experiments involving HIBD modeling, SPC treatment, and interventions with the PERK inhibitor GSK2656157 or the PERK activator CCT020312, administered 30minutes before modeling, followed by SPC treatment. Behavioral testing using the Morris water maze test and Neurological Deficiency Scale (NDS) was conducted. Additionally, Nissl staining assessed hippocampal CA1 area neuronal density, TUNEL staining evaluated hippocampal CA1 area neuronal apoptosis, and Western blot determined hippocampal CA1 area protein levels, including Bax, Bcl-2, p-PERK/PERK, p-eIF2/eIF2, ATF4, CHOP, GRP78, Bax, and Bcl-2 protein levels. Following SPC treatment, HIBD rats exhibited improved spatial learning and memory abilities, reduced neuronal apoptosis, increased neuronal density in the hippocampal CA1 area, elevated Bcl-2 protein level, decreased Bax protein levels, and decreased levels of endoplasmic reticulum stress pathway related proteins (p-PERK/PERK, p-eIF2/eIF2, ATF4, CHOP and GRP78). Pre-modeling treatment with the PERK inhibitor treatment improved outcomes in HIBD rats. However, pre-modeling treatment with the PERK activator CCT020312 counteracted the protective effects of SPC against HIBD in rats. In conclusion, SPC alleviates neuronal apoptosis in the hippocampus CA1 area of HIBD rats by inhibiting the endoplasmic reticulum stress pathway PERK/ATF4/CHOP, thereby mitigating HIBD in rats.

Imperatorin inhibits oxidative stress injury and neuroinflammation via the PI3K/AKT signaling pathway in the MPTP-induced Parkinson's disease mouse.

Parkinson's disease (PD) is a disorder of neurodegeneration. Imperatorin is an active natural furocoumarin characterized by antioxidant, anti-inflammatory, and potent vasodilatory properties. Therefore, we aimed to investigate the biological functions of imperatorin and its mechanisms against PD progression. C57BL/6 mice were intraperitoneally injected with 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP; 30 mg/kg) daily for 5 consecutive days to mimic PD conditions in vivo. The MPTP-induced PD model mice were intraperitoneally injected with imperatorin (5 mg/kg) for 25 consecutive days after MPTP administration. The motor and cognitive functions of mice were examined by rotarod test, hanging test, narrow beam test and Morris water maze test. After analysis of MWM test, the expression levels of tyrosine hydroxylase and Iba-1 in the substantia nigra pars compacta were measured by immunohistochemistry staining, immunofluorescence staining and western blotting. The expression levels of striatal dopamine and its metabolite 3,4-dihydroxyphenylacetic acid were also measured. The protein levels of inducible nitric-oxide synthase, cyclooxygenase-2, phosphorylated phosphatidylinositol 3-kinase (PI3K) and phosphorylated protein kinase B (Akt) in the mouse striatum were estimated by western blotting. The expression levels of proinflammatory cytokines including tumor necrosis factor, interleukin (IL)-1β and IL-6 in the mouse striatum were measured by ELISA kits. The expression levels of superoxide dismutase, malondialdehyde and glutathione in the mouse midbrains were measured with commercially available kits. TUNEL staining was performed to identify the apoptosis of midbrain cells. Histopathologic changes in the mouse striata were assessed by hematoxylin-eosin staining. Imperatorin treatment markedly improved spatial learning and memory abilities of MPTP-induced PD mice. The MPTP-induced dopaminergic neuron loss in the mouse striata was inhibited by imperatorin. Imperatorin also suppressed neuroinflammation and neuronal oxidative stress in the midbrains of MPTP-induced PD mice. Mechanistically, imperatorin treatment inhibited the MPTP-induced reduction in the PI3K/Akt pathway. Imperatorin treatment can prevent dopaminergic neuron degeneration and improve cognitive functions via its potent antioxidant and anti-inflammatory properties in an MPTP-induced PD model in mice by regulating the PI3K/Akt pathway.

PEGylated-liposomal astaxanthin ameliorates Aβ neurotoxicity and Alzheimer-related phenotypes by scavenging formaldehyde

Alzheimer’s disease (AD), which is a prevailing type of dementia, presents a significant global health concern. The current therapies do not meet clinical expectations. Amyloid-beta (Aβ) has been found to induce endogenous formaldehyde (FA) accumulation by inactivating FA dehydrogenase (FDH); in turn, excessive FA triggers Aβ aggregation that eventually leads to AD onset. Hence, scavenging FA by astaxanthin (ATX, a strong exogenous antioxidant) may be pursued as a promising disease-modifying approach. Here, we report that liposomal nanoparticles coupled with PEG (PEG-ATX@NPs) could enhance water-solubility of ATX and alleviate cognitive impairments by scavenging FA and reducing Aβ deposition. To enable drug delivery to the brain, liposomes were used to encapsulate ATX and then coupled with PEG, which produced liposomal nanoparticles (PEGATX@NPs) with a diameter of <100 nm. The PEG-ATX@NPs reduced Aβ neurotoxicity by both degrading FA and reducing FA-induced Aβ assembly in vitro. Intraperitoneal administration of PEG-ATX@NPs in APPswe/PS1dE9 mice (APP/PS1, a familial model of AD), not only decreased the levels of brain FA and malondialdehyde (MDA, a typical product of oxidative stress), but also attenuated both intracellular Aβ oligomerization and extracellular Aβ-related senile plaque (SP) formation. These pathological changes were accompanied by rescued ability of spatial learning and memory. Collectively, PEG-ATX@NPs improved the water-solubility, bioavailability, and effectiveness of ATX. Thus, it has the potential to be developed as a safe and effective strategy for treating AD.

Lasting mesothalamic dopamine imbalance and altered exploratory behavior in rats after a mild neonatal hypoxic event.

Adversities during the perinatal period can decrease oxygen supply to the fetal brain, leading to various hypoxic brain injuries, which can compromise the regularity of brain development in different aspects. To examine the catecholaminergic contribution to the link between an early-life hypoxic insult and adolescent behavioral aberrations, we used a previously established rat model of perinatal hypoxia but altered the hypobaric to normobaric conditions. Exploratory and social behavior and learning abilities were tested in 70 rats of both sexes at adolescent age. Inherent vertical locomotion, sensory-motor functions and spatial learning abilities were explored in a subset of animals to clarify the background of altered exploratory behavior. Finally, the concentrations of dopamine (DA) and noradrenaline in midbrain and pons, and the relative expression of genes for DA receptors D1 and D2, and their down-stream targets (DA- and cAMP-regulated phosphoprotein, Mr 32 kDa, the regulatory subunit of protein kinase A, and inhibitor-5 of protein phosphatase 1) in the hippocampus and thalamus were investigated in 31 rats. A lesser extent of alterations in exploratory and cognitive aspects of behavior in the present study suggests that normobaric conditions mitigate the hypoxic injury compared to the one obtained under hypobaric conditions. Increased exploratory rearing was the most prominent consequence, with impaired spatial learning in the background. In affected rats, increased midbrain/pons DA content, as well as mRNA levels for DA receptors and their down-stream elements in the thalamus, but not the hippocampus, were found. We can conclude that a mild hypoxic event induced long-lasting disbalances in mesothalamic DA signaling, contributing to the observed behavioral alterations. The thalamus was thereby indicated as another structure, besides the well-established striatum, involved in mediating hypoxic effects on behavior through DA signaling.

Obstructive Sleep Apnea Plasma-Derived Exosomes Mediate Cognitive Impairment Through Hippocampal Neuronal Cell Pyroptosis

ObjectiveObstructive sleep apnea (OSA) is associated with impaired cognitive function. Exosomes are secreted by most cells and play a role in OSA-associated cognitive impairment (CI). The aim of this study was to investigate whether OSA plasma-derived exosomes cause CI through hippocampal neuronal cell pyroptosis, and to identify exosomal miRNAs in OSA plasma-derived. Materials and MethodsPlasma-derived exosomes were isolated from patients with severe OSA and healthy comparisons. Daytime sleepiness and cognitive function were assessed using the Epworth Sleepiness Scale (ESS) and the Beijing version of the Montreal Cognitive Assessment Scale (MoCA). Exosomes were coincubated with mouse hippocampal neurons (HT22) cells to evaluate the effect of exosomes on pyroptosis and inflammation of HT22 cells. Meanwhile, exosomes were injected into C57BL/6 male mice via caudal vein, and then morris water maze was used to evaluate the spatial learning and memory ability of the mice, so as to observe the effects of exosomes on the cognitive function of the mice. Western blot and qRT-PCR were used to detect the expressions of Gasdermin D (GSDMD) and Caspase-1 to evaluate the pyroptosis level. The expression of IL-1β, IL-6, IL-18 and TNF-α was detected by qRT-PCR to assess the level of inflammation. Correlations of GSDMD and Caspase-1 expression with clinical parameters were evaluated using Spearman's rank correlation analysis. In addition, plasma exosome miRNAs profile was identified, followed by Gene Ontology (GO) term and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways. ResultsCompared to healthy comparisons, body mass index (BMI), apnea-hypopnea index (AHI), oxygen desaturation index (ODI), and ESS scores were increased in patients with severe OSA, while lowest oxygen saturation during sleep (LSaO2), mean oxygen saturation during sleep (MSaO2) and MoCA scores were decreased. Compared to the PBS group (NC) and the healthy comparison plasma-derived exosomes (NC-EXOS), the levels of GSDMD and Caspase-1 and IL-1β, IL-6, IL-18 and TNF-α were increased significantly in the severe OSA plasma-derived exosomes (OSA-EXOS) coincubated with HT22 cells. Compared to the NC and NC-EXOS groups, the learning and memory ability of mice injected with OSA-EXOS was decreased, and the expression of GSDMD and Caspase-1 in hippocampus were significantly increased, along with the levels of IL-1β, IL-6, IL-18 and TNF-α. Spearman correlation analysis found that clinical AHI in HCs and severe OSA patients was positively correlated with GSDMD and Caspase-1 in HT22 cells from NC-EXOS and OSA-EXOS groups, while negatively correlated with clinical MoCA. At the same time, clinical MoCA in HCs and severe OSA patients was negatively correlated with GSDMD and Caspase-1 in HT22 cells from NC-EXOS and OSA-EXOS groups. A unique exosomal miRNAs profile was identified in OSA-EXOS group compared to the NC-EXOS group, in which 28 miRNAs were regulated and several KEGG and GO pathways were identified. ConclusionsThe results of this study show a hypothesis that plasma-derived exosomes from severe OSA patients promote pyroptosis and increased expression of inflammatory factors in vivo and in vitro, and lead to impaired cognitive function in mice, suggesting that OSA-EXOS can mediate CI through pyroptosis of hippocampal neurons. In addition, exosome cargo from OSA-EXOS showed a unique miRNAs profile compared to NC-EXOS, suggesting that plasma exosome associated miRNAs may reflect the differential profile of OSA related diseases, such as CI.

Erythrocyte membrane-coated nanocarriers modified by TGN for Alzheimer's disease

Alzheimer's disease (AD) is an aging-related neurodegenerative disease, and the main pathological feature was β-amyloid protein (Aβ) deposition. Recently, bioactive materials-based drug delivery system has been widely investigated for the treatment of AD. In this study, we developed a red blood cells (RBC) membrane-coated polycaprolactone (PCL) nanoparticles (NPs) loading with a therapeutic agent for AD, curcumin (Cur). A functional peptide TGNYKALHPHN (TGN) was conjugated to the surface of membrane for blood-brain barrier (BBB) transport (TGN-RBC-NPs-Cur). TGN peptide can be recognized by receptors on the BBB and has great potential for brain transport. To confirm the targeted delivery of Cur to the brain, a cell co-culturing immortalized human cerebral microvascular endothelial cells and human brain astrocytes glioblastoma (hCMEC/D3 and U-118MG) in vitro model was established. As a result, the BBB transporting ratio of TGN-RBC-NPs-FITC was 29.64% at 12 h which was approximately eight-fold than RBC-NPs-FITC. The improvement of drug accumulation in the AD lesion was confirmed by the NPs modified with the BBB-penetrating peptide in the fluorescence imaging and quantitative analysis with UPLC-MS/MS in vivo. The neuroprotective effects were evaluated with new object recognition behavioral test, in vitro AD cell model, dendritic spine stain, GFAP and IBA1 immunofluorescence stain. The spatial learning and memory abilities of the AD model mice treated with TGN-RBC-NPs-Cur were obviously enhanced compared with the AD control mice and were also better than Cur at the same dosage. These results were consistent with the values of protection index of rat adrenal pheochromocytoma cells (PC12 cells) treated by Aβ25–35. TGN-RBC-NPs-Cur increased the dendritic segments densities and restrained activation of microglia and astrocytes of AD mice, as well as reversed cognitive function of AD mice. All of the results demonstrated TGN-RBC-NPs-Cur a promising therapeutic strategy for delaying the progression of AD by designing biomimetic nanosystems to deliver drugs into the brain.

Restoration of Spatial Learning Through Oral Administration of Lipopolysaccharides in Diabetes-related Cognitive Dysfunction.

In a previous report, our group showed that oral administration of lipopolysaccharides (LPS) from Pantoea agglomerans can prevent the progression of streptozotocin (STZ)-induced diabetes-related cognitive dysfunction (DRCD) in mice without causing significant side-effects. However, the treatment effects of oral administration of LPS to DRCD remain unknown. We modified our previous animal experimental model to investigate whether oral administration of LPS can recover cognitive function after DRCD onset. The Morris water maze (MWM) revealed a significant decrease in learning and memory abilities at 13 days after intracerebroventricular administration of STZ, thereby providing evidence of the occurrence of DRCD in the animal model. Oral administration of LPS (1 mg/kg per day) started after cognitive impairment was observed. After 28 days of treatment, mice receiving LPS via the oral route showed significant recovery of spatial learning ability, a symptom of early dementia, while only a trend toward recovery was seen for spatial memory compared to the untreated group. These results, limited to MWM, suggest that oral administration of LPS is a promising therapeutic strategy for restoring decreased spatial learning ability.

Atorvastatin Calcium Ameliorates Cognitive Deficits Through the AMPK/Mtor Pathway in Rats with Vascular Dementia.

In this study, the protective effects of atorvastatin calcium (AC) on nerve cells and cognitive improvement in vivo and in vitro were investigated by establishing cell models and vascular dementia (VD) rat models. VD is a neurodegenerative disease characterized by cognitive deficits caused by chronic cerebral hypoperfusion. AC has been studied for its potential to cure VD but its efficacy and underlying mechanism are still unclear. The mechanism of action of AC on cognitive deficits in the early stages of VD is unclear. Here, the 2-vessel occlusion (2-VO) model in vivo and the hypoxia/reoxygenation (H/R) cell model in vitro was established to investigate the function of AC in VD. The spatial learning and memory abilities of rats were detected by the Morris method. The IL-6, tumour necrosis factor-α (TNF-α), malondialdehyde (MDA) and superoxide dismutase (SOD) in cell supernatant was tested by ELISA kits. After behavioural experiments, rats were anaesthetized and sacrificed, and their brains were extracted. One part was immediately fixed in 4% paraformaldehyde for H&E, Nissl, and immunohistochemical analyses, and the other was stored in liquid nitrogen. All data were shown as mean ± SD. Statistical comparison between the two groups was performed by Student's t-test. A two-way ANOVA test using GraphPad Prism 7 was applied for escape latency analysis and the swimming speed test. The difference was considered statistically significant at p < 0.05. AC decreased apoptosis, increased autophagy, and alleviated oxidative stress in primary hippocampal neurons. AC regulated autophagy-related proteins in vitro by western blotting. VD mice improved cognitively in the Morris water maze. Spatial probing tests showed that VD animals administered AC had considerably longer swimming times to the platform than VD rats. H&E and Nissl staining showed that AC reduces neuronal damage in VD rats. Western blot and qRT-PCR indicated that AC in VD rats inhibited Bax and promoted LC3-II, Beclin-1, and Bcl-2 in the hippocampus region. AC also improves cognition via the AMPK/mTOR pathway. This study found that AC may relieve learning and memory deficits as well as neuronal damage in VD rats by changing the expression of apoptosis/autophagy-related genes and activating the AMPK/mTOR signalling pathway in neurons.