Microglia synchronizes with the circadian rhythm of the glymphatic system and modulates glymphatic system function.

Microglia, as immune cells in the central nervous system, possess the ability to adapt morphologically and functionally to their environment. Glymphatic system, the principal waste clearance system in the brain, exhibits circadian rhythms. However, the impact of microglia on the glymphatic system function remains unknown. In this study, we explored the intricate relationship between microglia and the glymphatic system. Examining diurnal patterns, we identified synchronized behaviors in glymphatic activity and microglial morphology, peaking during sleep and exhibiting distinct changes in branching complexity. Depleting microglia using PLX5622 or in P2Y12 knockout mice enhanced glymphatic function. Chemogenetic manipulation of microglia demonstrated that activating HM3D improved glymphatic function, while inhibiting HM4D unexpectedly increased microglial complexity. These findings highlight the dynamic influence of microglia on the glymphatic system.

Aquaporin 4 Mediates the Effect of Iron Overload on Hydrocephalus After Intraventricular Hemorrhage.

BACKGROUND: Iron overload plays an important role in hydrocephalus development following intraventricular hemorrhage (IVH). Aquaporin 4 (AQP4) participates in the balance of cerebrospinal fluid secretion and absorption. The current study investigated the role of AQP4 in the formation of hydrocephalus caused by iron overload after IVH. METHODS: There were three parts to this study. First, Sprague-Dawley rats received an intraventricular injection of 100 µl autologous blood or saline control. Second, rats had IVH and were treated with deferoxamine (DFX), an iron chelator, or vehicle. Third, rats had IVH and were treated with 2-(nicotinamide)-1,3,4-thiadiazole (TGN-020), a specific AQP4 inhibitor, or vehicle. Rats underwent T2-weighted and T2* gradient-echo magnetic resonance imaging to assess lateral ventricular volume and intraventricular iron deposition at 7, 14, and 28 days after intraventricular injection and were then euthanized. Real-time quantitative polymerase chain reaction, western blot analysis, and immunofluorescence analyses were conducted on the rat brains to evaluate the expression of AQP4 at different time points. Hematoxylin and eosin-stained brain sections were obtained to assess the ventricular wall damage on day 28. RESULTS: Intraventricular injection of autologous blood caused a significant ventricular dilatation, iron deposition, and ventricular wall damage. There was increased AQP4 mRNA and protein expression in the periventricular tissue in IVH rats through day 7 to day 28. The DFX treatment group had a lower lateral ventricular volume and less intraventricular iron deposition and ventricular wall damage than the vehicle-treated group after IVH. The expression of AQP4 protein in periventricular tissue was also inhibited by DFX on days 14 and 28 after IVH. The use of TGN-020 attenuated hydrocephalus development after IVH and inhibited the expression of AQP4 protein in the periventricular tissue between day 14 and day 28 without a significant effect on intraventricular iron deposition or ventricular wall damage. CONCLUSIONS: AQP4 located in the periventricular area mediated the effect of iron overload on hydrocephalus after IVH.

Neutrophilic granulocyte percentage is associated with anxiety in Chinese hospitalized heart failure patients.

BACKGROUND: In patients with heart failure, anxiety disorder is common and associated with adverse prognosis. This study intended to find more confounding factors of Chinese heart failure patients. METHODS: We enrolled 284 hospitalized heart failure patients, whose New York Heart Association (NYHA) classed as II-IV and left ventricular ejection fraction (LVEF) ≤ 45%. All the patients were scaled in Hamilton Rating Scale for Anxiety (14-items) (HAM-A14). Ordinal logistic regression analysis was performed to examine the association of correlated factors with anxiety disorder. RESULTS: There were 184 patients had anxiety accounting for 64.8% of all 284 hospitalized heart failure patients. The neutrophilic granulocyte percentage, urea nitrogen, total bilirubin and brain natriuretic peptide were positively associated with HAM-A14 score, meanwhile, the hemoglobin, red blood cells counts, albumin and LVEF were negatively associated with HAM-A14 score (All P < 0.05). After the adjustments of sex, hemoglobin, urea nitrogen, total bilirubin, albumin and brain natriuretic peptide, the neutrophilic granulocyte percentage was significantly associated with anxiety (OR = 43.265, P = 0.012). The neutrophilic granulocyte percentage was 0.616 ± 0.111, 0.640 ± 0.102, 0.681 ± 0.106 and 0.683 ± 0.113 in heart failure patients with no anxiety, possible anxiety, confirmed anxiety and obvious anxiety, respectively. CONCLUSIONS: Neutrophilic granulocyte percentage as well as the traditional risk factors such as sex, urea nitrogen and brain natriuretic peptide is associated with anxiety in hospitalized heart failure patients.

Inhibiting PI3K leads to glucose metabolism disturbance in default mode network.

BACKGROUND: As the symbolic pathological changes of Alzheimer's disease (AD), hyperphosphorylated tau and amyloid plaque play important roles in the progression of the disease. In AD patients, the neural activity in default mode network is abnormal at different stages of the disease, and showed a hypoconnective status. Inhibition of phosphatidylinositol-3-kinase (PI3K) activates glycogen synthase kinase 3 beta (GSK-3ß) and induces tau phosphorylation. OBJECTIVE: We speculated that inhibiting cerebral PI3K altered the glucose metabolism in DMN. We aimed to explore the impacts of PI3K inhibition on tau phosphorylation, cerebral glucose metabolism, and synaptic plasticity. METHODS: We injected wortmannin, an inhibitor of PI3K, lateral ventricularly in rats to mimic the pathology of AD. Immunohistochemistry was carried out to analyze the expression of phosphorylated tau. Region-specific glucose metabolism in the brain was analyzed using 18F-FDG PET imaging. In vivo long-term potentiation (LTP) in the hippocampus was detected to assess the synaptic plasticity. RESULTS: The results show that the phosphorylated tau at T231 increased and the hippocampal LTP was suppressed 24 h after wortmannin administration. In the DMN, glucose uptake was significantly high, indicating a neural activity disturbance. CONCLUSION: We conclude that targeting PI3K-GSK-3ß pathway to mimic AD tau pathology interrupted the glucose metabolism of DMN brain regions.

Polyunsaturated fatty acid supplement alleviates depression-incident cognitive dysfunction by protecting the cerebrovascular and glymphatic systems.

INTRODUCTION: Depression, the most prevalent mood disorder, has high comorbidity with cerebrovascular disease and cognitive decline. However, there is little understanding of the cellular mechanisms involved in depression and its comorbid cerebrovascular damage and cognition impairment. Here, we tested the prediction that the chronic unpredictable mild stress (CUMS) mouse model would manifest in disturbed glymphatic function and that dietary supplementation with polyunsaturated fatty acids (PUFA) could ameliorate these deficits while alleviating the depression-associated cognitive decline. METHODS: To test the treatment effects of PUFA or Es on behaviours, we applied the tail suspension, open field, and sucrose preference tests to assess depressive symptoms, and applied the Morris water maze test to assess cognition in groups of control, chronic unpredictable mild stress (CUMS), PUFA, and escitalopram (Es) treatment. We measured the extracellular concentrations of dopamine (DA), 5-hydroxytryptamine (5-HT) and noradrenaline (NA) in microdialysates from prefrontal cortex (PFC) by liquid chromatography mass spectrometry. Glia cells and inflammatory factors were analysed with fluorescent immunochemistry and western blot, respectively. We tested brain vasomotor function with two-photon and laser speckle imaging in vivo, and measured glymphatic system function by two-photon imaging in vivo and fluorescence tracer imaging ex vivo, using awake and anesthetized mice. Besides, we monitored cortical spreading depression by laser speckle imaging system. AQP4 depolarization is analysed by fluorescent immunochemistry and western blot. RESULTS: We confirmed that CUMS elicited depression-like and amnestic symptoms, accompanied by decreased monoamines neurotransmitter concentration in PFC and upregulated neuroinflammation markers. Moreover, CUMS mice showed reduced arterial pulsation and compliance in brain, and exhibited depolarized expression of AQP4, thus indicating glymphatic dysfunction both in awake and anesthetized states. PUFA supplementation rescued depression-like behaviours of CUMS mice, reduced neuroinflammation and cerebrovascular dysfunction, ultimately improved cognitive performance, all of which accompanied by restoring glymphatic system function. In contrast, Es treatment alleviated only the depression-like behavioural symptoms, while showing no effects on glymphatic function and depression-incident cognitive deficits. CONCLUSIONS: The CUMS depression model entails suppression of the glymphatic system. PUFA supplementation rescued most behavioural signs of depression and the associated cognitive dysfunction by restoring the underlying glymphatic system disruption and protecting cerebral vascular function.

Morin exerts protective effects on encephalopathy and sepsis-associated cognitive functions in a murine sepsis model.

Sepsis-associated encephalopathy (SAE) often leads to cognitive impairments in the rest life of septic survivors. The potential pathological changes of SAE are complicated and have not been fully understood. Morin, a flavone compound exhibiting neuroprotective activity and anti-inflammation effect, was employed to treat with CLP-induced septic mice in our study. The data from a novel object recognition test and tail suspension test indicated that morin treatment reversed cognitive dysfunction and relieved depressive-like behaviors in septic mice. Morin down-regulated the expressions of IL-6, MCP-1, TNF-α and IL-10 in serum and diminished microglia activation in septic mice. Additionally, Western blot results showed that morin reduced the phosphokinase GSK3ß activity and elevated the phosphatase PP2A activity, which led to lower tau phosphorylation. Morin reduced Aß deposition and protected the synapse integrity, which might be the possible mechanism of protecting cognitive functions in septic mice. In conclusion, we identified that morin exerted anti-inflammation and anti-neurodegeneration effects in septic mice, and prevented further cognitive impairments.

Soluble epoxide hydrolase inhibition alleviated cognitive impairments via NRG1/ErbB4 signaling after chronic cerebral hypoperfusion induced by bilateral carotid artery stenosis in mice.

Cerebral ischemic stroke is associated with a high rate of incidence, prevalence and mortality globally. Carotid artery stenosis, which is mainly caused by atherosclerosis plaque, results in chronic cerebral hypoperfusion and predominantly increases the risk of ischemic stroke. In the present study, we used bilateral common carotid artery stenosis (BCAS) model by placing microcoils of 0.18 mm diameter encompassing both common carotid arteries respectively, to mimic the pathogenesis of carotid artery atherosclerosis and intensively explore the pathology. We found that BCAS injury for 1 month impaired spatial cognitive functions significantly, and inhibited synaptic plasticity, including hippocampal long-term potentiation (LTP) inhibition, dendritic spine density reduction and synaptic associative proteins disorder. BCAS-induced cerebral hypoperfused mice treated with 1-(1-propanoylpiperidin-4-yl)-3-[4-(trifluoromethoxy)phenyl]urea (TPPU), a potent soluble epoxide hydrolase (sEH) inhibitor, exhibited amelioration of cognitive dysfunction and improved synaptic plasticity. The neural protective effects of TPPU on BCAS-induced cerebral hypoperfusion might due to activation of neuregulin-1 (NRG1)/ErbB4 signaling, and triggered PI3K-Akt pathways subsequently. Our results suggested that sEH inhibition could exert multi-target protective effects and alleviate spatial cognitive dysfunctions after chronic cerebral hypoperfusion in mice.

Expression of human Tau40 in the medial entorhinal cortex impairs synaptic plasticity and associated cognitive functions in mice.

Entorhinal cortex (EC) is the initial brain region that suffers abnormal tau in Alzheimer's disease (AD). Whether overexpression of human tau (htau40) in EC disrupts cognitive function and synaptic plasticity in AD has not been fully elucidated. To investigate the effects of htau40 on the pathology and associated mechanisms of early stage of AD in mice, an adeno-associated virus-based htau40 transduced in medial EC (mEC) mouse model was established. The results showed that htau40 restrictedly expressed in mEC after transduction. The memory function and long-term potentiation (LTP) of dentate gyrus (DG) were significantly impaired by overexpression of htau40 in mEC after transduction at 3 and 6 months. However, the abnormities of neurons and neurotransmitters in mEC started at just 1 month after transduction. The resting membrane potential was increased and paired pulse facilitates was depressed, but the action potential amplitude, threshold, and half width did not alter after htau40 transduction at 1 month. The levels of inhibitory neurotransmitters were up regulated whereas level of lactate was decreased. Our study demonstrated that htau40 in mEC impaired cognition and synaptic plasticity of perforant path (PP)-DG, which simulated early stage of AD and elucidated the mechanism of that htau40 overexpression in mEC may be associated with the development of AD.

Effect of recurrent severe hypoglycemia on cognitive performance in adult patients with diabetes: A meta-analysis.

The purpose of this study was to investigate the existence and extent of cognitive impairment in adult diabetes mellitus (DM) patients with episodes of recurrent severe hypoglycemia, by using meta-analysis to synthesize data across studies. PubMed, EMBASE and Cochrane library search engines were used to identify studies on cognitive performance in DM patients with recurrent severe hypoglycemia. Random-effects meta-analysis was performed on seven eligible studies using an inverse-variance method. Effect sizes, which are the standardized differences between the experimental group and the control group, were calculated. Of the 853 studies, 7 studies met the inclusion criteria. Compared with control subjects, the adult DM patients with episodes of recurrent severe hypoglycemia demonstrated a significantly lowered performance on memory in both types of DM patients, and poor performance of processing speed in type 2 DM patients. There was no significant difference between adult DM patients with and those without severe hypoglycemia in other cognitive domains such as general intelligence, executive function, processing speed and psychomotor efficiency. Our results seem to confirm the hypothesis that cognitive dysfunction is characterized by worse memory and processing speed in adult DM patients with a history of recurrent severe hypoglycemia, whereas general intelligence, executive function, and psychomotor efficiency are spared.

Soluble epoxide hydrolase inhibition Promotes White Matter Integrity and Long-Term Functional Recovery after chronic hypoperfusion in mice.

Chronic cerebral hypoperfusion induced cerebrovascular white matter lesions (WMLs) are closely associated with cognitive impairment and other neurological deficits. The mechanism of demyelination in response to hypoperfusion has not yet been fully clarified. Soluble epoxide hydrolase (sEH) is an endogenous key enzyme in the metabolic conversion and degradation of P450 eicosanoids called epoxyeicosatrienoic acids. Inhibition of sEH has been suggested to represent a prototype "combination therapy" targeting multiple mechanisms of stroke injury with a single agent. However, its role in the pathological process after WMLs has not been clarified. The present study was to investigate the role of a potent sEH inhibitor, 1-trifluoromethoxyphenyl-3-(1-propionylpiperidin-4-yl) urea (TPPU), on multiple elements in white matter of mice brain after chronic hypoperfusion. Adult male C57BL/6 mice were subjected to bilateral carotid artery stenosis (BCAS) to induce WMLs. Administration of TPPU significantly inhibited microglia activation and inflammatory response, increased M2 polarization of microglial cells, enhanced oligodendrogenesis and differentiation of oligodendrocytes, promoted white matter integrity and remyelination following chronic hypoperfusion. Moreover, these cellular changes were translated into a remarkable functional restoration. The results suggest that sEH inhibition could exert multi-target protective effects and alleviate cognitive impairment after chronic hypoperfusion induced WMLs in mice.

TPPU protects tau from H2O2-induced hyperphosphorylation in HEK293/tau cells by regulating PI3K/AKT/GSK-3ß pathway.

Neurofibrillary pathology of abnormally hyperphosphorylated tau is a hallmark of Alzheimer's disease (AD) and other tauopathies. Phosphatidylinositol 3-kinase (PI3K)/Akt/glycogen synthase kinase-3 beta (GSK-3ß) signaling pathway is pivotal for tau phosphorylation. Inhibition of soluble epoxide hydrolase (sEH) metabolism has been shown to effectively increase the accumulation of epoxyeicosatrienoic acids (EETs), which are cytochrome P450 metabolites of arachidonic acid and have been demonstrated to have neuroprotective effects. However, little is known about the role of sEH in tau phosphorylation. The present study investigated the role of a sEH inhibitor, 1-(1-propanoylpiperidin-4-yl)-3-[4-(trifluoromethoxy)phenyl] urea (TPPU), on H2O2-induced tau phosphorylation and the underlying signaling pathway in human embryonic kidney 293 (HEK293)/Tau cells. We found that the cell viability was increased after TPPU treatment compared to control in oxidative stress. Western blotting and immunofluorescence results showed that the levels of phosphorylated tau at Thr231 and Ser396 sites were increased in H2O2-treated cells but dropped to normal levels after TPPU administration. H2O2 induced an obvious decreased phosphorylation of GSK-3ß at Ser9, an inactive form of GSK-3ß, while there were no changes of phosphorylation of GSK-3ß at Tyr216. TPPU pretreatment maintained GSK-3ß Ser 9 phosphorylation. Moreover, Western blotting results showed that TPPU upregulated the expression of p-Akt. The protective effects of TPPU were found to be inhibited by wortmannin (WT, a specific PI3K inhibitor). In conclusion, these results suggested that the protective effect of TPPU on H2O2-induced oxidative stress is associated with PI3K/Akt/GSK-3ß pathway.

Elevated Homocysteine Level Related to Poor Outcome After Thrombolysis in Acute Ischemic Stroke.

BACKGROUND Hyperhomocysteinemia (HHcy) is a well-known risk factor for ischemic stroke. However, whether HHcy can influence the treatment outcome of acute ischemic stroke (AIS) patients has yet to be fully determined. In this study, we investigated the relationship between serum homocysteine (Hcy) level and prognosis in AIS patients who received tissue plasminogen activator (tPA) treatment. MATERIAL AND METHODS Patients were recruited according to the research criteria and grouped by their serum Hcy levels. Neurological outcome was evaluated by National Institute of Health Stroke Scale (NIHSS) score system before and 1 week after treatment, and functional outcome was evaluated by modified Rankin Scale (MRS) score system after 3 months. All patients took CT/MRI examination to detect cerebral hemorrhage in 24 hours after tPA treatment. Receiver operating characteristic curve (ROC) was employed to assess if serum homocysteine level can be used as an index to predict the outcome after tPA treatment. RESULTS The mean (±SD) serum Hcy level of 194 patients was 22.62±21.23 µmol/L. After 1-week tPA treatment, the NIHSS scores of high Hcy level group were significantly higher than those of low level group (p<0.05), meantime the high Hcy group showed obvious symptomatic intracerebral hemorrhage risk after 24 hours (p<0.05). Poor outcome was presented in mRS score results after 3 months in high Hcy level group, which compared with low Hcy level group (p<0.01). The ROC showed that Hcy level was a moderately sensitive and specific index to predict the prognosis with an optimal cut-off value at 19.95 µmol/L (sensitivity [58.2%], specificity [80.3%]). CONCLUSIONS High serum homocysteine level could potentially predict poor prognosis in acute ischemic stroke patients after tPA treatment.

Epoxyeicosanoid Signaling Provides Multi-target Protective Effects on Neurovascular Unit in Rats After Focal Ischemia.

Multiple players are involved in the highly complex pathophysiologic responses after stroke. Therefore, therapeutic approaches that target multiple cellular elements of the neurovascular unit in the damage cascade hold considerable promise for the treatment of stroke. Cytochrome P450 (CYP) epoxygenases metabolize arachidonic acid to biologically active eicosanoids called epoxyeicosatrienoic acids (EETs), which are further converted by soluble epoxide hydrolase (sEH) to less bioactive diols. EETs have been shown to exert direct cytoprotective effects upon several individual components of the neurovascular unit under simulated ischemic conditions in vitro. However, the cellular mechanism underlying EET-mediated neuroprotective effects after ischemia remains to be clarified. In this study, we investigated the effects of 14,15-EET and 12-(3-adamantan-1-yl-ureido)dodecanoic acid (AUDA), a selective inhibitor of sEH, on multiple elements of neurovascular unit of the rat brain after middle cerebral artery occlusion-induced focal ischemia. The results showed that exogenous administration of 14,15-EET or AUDA could suppress astrogliosis and glial scar formation, inhibit microglia activation and inflammatory response, promote angiogenesis, attenuate neuronal apoptosis and infarct volume, and further promote the behavioral function recovery after focal ischemia. The results suggest that epoxyeicosanoid signaling is a promising multi-mechanism therapeutic target for the treatment of stroke.

[Comparative genomic hybridization: the profile of chromosomal imbalances in rhabdomyosarcoma].

OBJECTIVE: To characterize the profile of chromosomal imbalances of rhabdomyosarcoma(RMS). METHODS: Comparative genomic hybridization (CGH) was used to investigate genomic imbalances in 25 cases of primary RMS including 10 cases of alveolar rhabdomyosarcoma (ARM), 12 cases of embryonic rhabdomyosarcoma (ERMS), 3 cases of polymorphic rhabdomyosarcoma (PRMS) and 2 RMS cell lines (A240 originated from ARMS and RD from PRMS), with correlation to histological type, pathologic grading, clinical staging, gender and age, respectively. RESULTS: All twenty-five rhabdomyosarcomas showed evidence of increased or decreased DNA sequence copy numbers involving one or more regions of the genome. (1) The frequently gained chromosome regions in RMS were 2p, 12q, 6p, 9q, 10q, 1p, 2q, 6q, 8q, 15q, 18q, and the frequently lost chromosome regions were 3p, 11p, 6p. (2) The frequently gained chromosome arms in ARMS were 12q, 2p, 6, 2q, 4q, 10q, 15q. The frequently lost chromosome arms were 3p, 6p, 1q, 5q. The frequently gained chromosome regions in ERMS were 7p, 9q, 2p, 18q, 1p, 8q. The frequently lost chromosome arms in ERMS were 11p. (3) The frequently gained chromosome arms in translocation associated RMS were 12q, 2, 6, 10q, 4q and 15q (> 30%), 3p, 6p, 5q (> 30%) were the frequently loss chromosome arms. The frequently gained chromosome regions in non-translocation associated RMS were 2p, 9q, 18q (> 30%), and 11p, 14q (> 30%) were the frequently loss chromosome regions. Gain of 12q was significantly correlated with the translocation-associated tumors (P < 0.05). (4) Gains of 9q was significantly correlated with clinical staging (P < 0.05). CONCLUSIONS: Gain of 2p, 12q, 6p, 9q, 10q, 1p, 2q, 6q, 8q, 15q, 18q and loss of 3p, 11p, 6p may be involved in the tumorigenesis of RMS. Gains of 12q may be correlated with gene fusion/chromosomal translocation in ARMS. Gains of 9q may be correlated with an early tumor stage of RMS.