Memory Impairment Research Articles

Multicenter Evaluation of Memory Remediation in Traumatic Brain Injury With Donepezil: A Randomized Controlled Trial.

Memory impairments are common chronic and functionally important consequences of traumatic brain injury (TBI). Among patients with persistent verbal memory impairments due to TBI-related cholinergic deficits, donepezil (an acetylcholinesterase inhibitor) may improve these and related problems. The Multicenter Evaluation of Memory Remediation in TBI with Donepezil (MEMRI-TBI-D) study, a four-site, randomized, parallel-group, double-blind, placebo-controlled, 10-week clinical trial, evaluated the efficacy of donepezil on verbal memory impairments, co-occurring cognitive and noncognitive neuropsychiatric problems, and functional status among persons with severe, persistent, and functionally limiting verbal memory problems at least 6 months after mild, moderate, or severe TBI. Efficacy, safety, and tolerability measures were assessed. Seventy-five participants were randomly assigned to donepezil (N=37) and placebo (N=38) groups. In both modified intent-to-treat and per-protocol analyses, donepezil significantly improved memory (i.e., verbal learning, as measured by the Hopkins Verbal Learning Test-Revised Total Trials 1-3, the primary outcome measure) when compared with placebo. Treatment-responder rates in the donepezil and placebo groups were 42% and 18%, respectively, yielding a number needed to treat of 3.5. Among donepezil responders, delayed recall and processing speed also improved significantly. Treatment-emergent adverse event rates for donepezil and placebo were 46% and 8%, respectively, and mild or moderate (85%); diarrhea and nausea were significantly more common in the donepezil group, yielding a number needed to harm of 6.25 and a likelihood to be helped or harmed ratio of 1.79. These results suggest that donepezil is an efficacious treatment for severe, persistent memory impairments after predominantly severe TBI, with a relatively favorable safety and tolerability profile.

Sub-acute stroke demonstrates altered beta oscillation and connectivity pattern in working memory

IntroductionWorking memory (WM) is suggested to play a pivotal role in relearning and neural restoration during stroke rehabilitation. Using EEG, this study investigated the oscillatory mechanisms of WM in subacute stroke.MethodsThis study included 48 first subacute stroke patients (26 good-recovery, 22 poor-recovery, based on prognosis after a 4-week period) and 24 matched health controls. We examined the oscillatory characteristics and functional connectivity of the 0-back WM paradigm and assessed their associations with prognosis.ResultsPatients of poor recovery are characterised by a loss of significant beta rebound, beta-band connectivity, as well as impaired working memory speed and performances. Meanwhile, patients with good recovery have preserved these capacities to some extent. Our data further identified beta rebound to be closely associated with working memory speed and performances.ConclusionsWe provided novel findings that beta rebound and network connectivity as mechanistic evidence of impaired working memory in subacute stroke. These oscillatory features could potentially serve as a biomarker for brain stimulation technologies in stroke recovery.

Crocin Improves Cognitive Impairment in LPS-treated Rats through Anti-Apoptotic, Anti-Inflammatory, and Antioxidant Activities.

Brain inflammation and oxidative stress play critical roles in neuronal apoptosis and memory dysfunction in Alzheimer's disease. Crocin, a natural carotenoid in the stigma of saffron, possesses radical scavenging, anti-inflammatory, and anti-apoptotic properties. This study investigates the protective impact of crocin on neuronal apoptosis, oxidative stress, neuroinflammation, and memory deficits induced by lipopolysaccharide (LPS) in rats. Male Wistar rats received 100mg/kg of crocin for 12 days, with LPS (1mg/kg, ip) injected on days 8-12. Spatial learning and memory were evaluated in the Morris water maze two hours after LPS injection. Gene expression of nuclear factor kappa B (NF-κB), tumor necrosis factor-α (TNF-α), caspase 3, and lipid peroxidation was assessed in hippocampal homogenates at the end of the behavioral test. Histopathological changes in the hippocampus and cerebral cortex were evaluated using H&E staining. The results indicated that LPS administration caused spatial learning and memory dysfunction (P = 0.001, P < 0.01) accompanied by upregulation of Nfkb, Tnfα, and Casp3 mRNA expression (P < 0.0001), increased TNF-α (P < 0.01) and lipid peroxidation level (P < 0.01), decreased total thiol concentration (P < 0.05), tissue damage and neuronal loss in the hippocampus (P < 0.0001). Furthermore, crocin treatment at a dosage of 100mg/kg attenuated learning and memory impairments (P = 0.001, P < 0.01), downregulated Nfkb, Tnfα, and Casp3 mRNA expression (P < 0.0001), decreased TNF-α level (P < 0.01) and lipid peroxidation (P < 0.05) and increased total thiol level (P < 0.05) in the hippocampus. Crocin also ameliorated LPS-induced pathological changes and neuronal loss in the hippocampus (P < 0.001) and cerebral cortex (P < 0.01). In conclusion, the neuroprotective effects of crocin against LPS-induced histopathological and behavioral changes could be attributed to its anti-apoptotic, anti-inflammatory, and radical-scavenging activities in the rat brain.

Th22 cells promote the transition from homeostatic to reactive microglia in diabetic encephalopathy.

Diabetic encephalopathy (DE) is one of the most serious complications of diabetes mellitus (DM), and its pathogenesis has not yet been clarified. Th22 cells are a newly discovered class of CD4+ T cells that play important roles in inflammatory, autoimmune and infectious diseases. However, it is unclear whether Th22 cells are involved in the pathogenesis of DE. We established a T2DM mouse model in vivo and cocultured Th22 cells with microglia under high glucose (HG) conditions in vitro. Cognitive dysfunction was evaluated using the Morris water maze (MWM) test; blood‒brain barrier (BBB) integrity was evaluated using the Evans blue (EB) extravasation assay; Th22 cells and IL-22 receptors were detected by immunofluorescence; and IL-1β, TNF-α, iNOS, CD86, Arg-1, and CD206 protein expression was measured by Western Blot (WB) analysis. Th22 cells passed through the BBB into the hippocampus and secreted interleukin-22 (IL-22), and the mice subsequently exhibited decreased learning and memory abilities. In the DE model, IL-22 promoted the transformation of homeostatic microglia into reactive microglia as well as the inflammatory response. Additionally, coculture of Th22 cells with BV2 microglia cultured under HG conditions increased the production of proinflammatory cytokines, and the microglia showed reactive changes. Mechanistically, IL-22Rα1 acted as a ligand, and IL-22 bound to IL-22Rα1 on microglia to drive primary microglia-induced inflammatory responses. Interestingly, interleukin-22 binding protein (IL-22BP) directly binds to IL-22Rα1 on microglia to inhibit the proinflammatory effects of IL-22. Th22 cells secrete IL-22 after passing through the BBB into the hippocampus and promote the transformation of homeostatic microglia into reactive microglia, which induces an inflammatory response, exacerbates learning and memory impairment and cognitive deficits, and contributes to and accelerates the development of DE.

The X-linked intellectual disability gene CUL4B is critical for memory and synaptic function

Cullin 4B (CUL4B) is the scaffold protein in the CUL4B-RING E3 ubiquitin ligase (CRL4B) complex. Loss-of-function mutations in the human CUL4B gene lead to syndromic X-linked intellectual disability (XLID). Till now, the mechanism of intellectual disability caused by CUL4B mutation still needs to be elucidated. In this study, we used single-nucleus RNA sequencing (snRNA-seq) to investigate the impact of CUL4B deficiency on the transcriptional programs of diverse cell types. The results revealed that depletion of CUL4B resulted in impaired intercellular communication and elicited cell type-specific transcriptional changes relevant to synapse dysfunction. Golgi-Cox staining of brain slices and immunostaining of in vitro cultured neurons revealed remarkable synapse loss in CUL4B-deficient mice. Ultrastructural analysis via transmission electron microscopy (TEM) showed that the width of the synaptic cleft was significantly greater in CUL4B-deficient mice. Electrophysiological experiments found a decrease in the amplitude of AMPA receptor-mediated EPSCs in the hippocampal CA1 pyramidal neurons of CUL4B-deficient mice. These results indicate that depletion of CUL4B in mice results in morphological and functional abnormalities in synapses. Furthermore, behavioral tests revealed that depletion of CUL4B in the mouse nervous system results in impaired spatial learning and memory. Taken together, the findings of this study reveal the pathogenesis of neurological disorders associated with CUL4B mutations and promote the identification of therapeutic targets that can halt synaptic abnormalities and preserve memory in individuals.

Losartan attenuates sex-dependent hypertension, neuroinflammation, and cognitive impairment in the aging male sprague-dawley rat.

The prevalence of hypertension increases with age and is the leading modifiable risk factor for cognitive impairment and dementia. At present, the neural mechanisms promoting hypertension across the lifespan are incompletely understood. Using the Sprague-Dawley (SD) rat as a model of normal aging, we hypothesized (1) blood brain barrier (BBB) disruption and neuroinflammation in the paraventricular nucleus (PVN) of the hypothalamus enhances sympathetic tone and contributes to age-dependent hypertension, (2) age-dependent hypertension is associated with cognitive impairment, and (3) lowering blood pressure in aged rats with established hypertension improves cognitive function. We found male, but not female, rats develop age-dependent hypertension with enhanced sympathetic tone, BBB disruption, and neuroinflammation in the PVN. Aged hypertensive male rats also showed impairments in recognition and spatial memory. Utilizing pharmacological interventions, blood pressure was lowered in male rats with established hypertension using either losartan (LOS) or hydrochlorothiazide. However, only losartan improved recognition memory. Further, LOS reduced BBB disruption, microglial activation, astrocyte reactivity, and proinflammatory cytokine expression in the PVN which we speculate contributes to a decrease in blood pressure. These data show SD rats develop age-dependent hypertension and cognitive impairment in a sex-dependent manner. However, not all antihypertensive agents improve cognitive function equally as only losartan, an angiotensin II type 1 receptor antagonist (AT1R) improved recognition memory. Thus, AT1R antagonists represent a potential therapeutic approach for treating cognitive decline in the aging population.

A Morphological and Behavioral Study of Demyelination and Remyelination in the Cuprizone Model: Insights into APLNR and NG2+ Cell Dynamics

Multiple sclerosis (MS) is a chronic neurodegenerative disorder involving demyelination. The cuprizone model is commonly used to study MS by inducing oligodendrocyte stress and demyelination. The subventricular zone (SVZ) plays a key role in neurogenesis, while the neuronal/glial antigen 2 (NG2) is a marker for immature glial cells, involved in oligodendrocyte differentiation. The apelin receptor (APLNR) is linked to neurogenesis and behavior modulation. This study explores the role of APLNR in NG2-positive cells during de- and remyelination phases in the experimental cuprizone mouse model. Thirty male C57BL/6 mice were divided into control (not treated), demyelination (5 weeks cuprizone administration), and remyelination (5 weeks cuprizone administration + 5 weeks recovery) groups. Histological examinations, immunohistochemistry, and immunofluorescence on serial coronal sections were conducted to evaluate corpus callosum (CC) morphology and APLNR and NG2 expression in the SVZ, in addition to behavioral assessments. The histological analysis showed a significant reduction in the CC’s thickness and area after five weeks of cuprizone exposure, followed by recovery five weeks post-exposure. During the demyelination phase, APLNR-expressing cells peaked while NG2-positive cells decreased. In the remyelination phase, APLNR-expressing cells declined, and NG2-positive cells increased. Confocal microscopy confirmed the co-localization of NG2 and APLNR markers. Statistically significant differences were observed across experimental groups. Correlation analyses highlighted associations between APLNR/NG2 cell counts and CC changes. Behavioral tests revealed impaired motor coordination and memory during demyelination, with gradual recovery during remyelination. Significant changes in the CC structure and the number of APLNR and NG2-positive cells were observed during de- and remyelination, suggesting that NG2-positive cells expressing APLNR may play a key role in remyelination.

AD-like neuropsychiatric dysfunction in a mice model induced by a combination of high-fat diet and intraperitoneal injection of streptozotocin.

Increasing data suggest a crucial relationship between glycolipid metabolic disorder and neuropsychiatric injury. The aim of this study is to investigate the behavioral performance changes and neuropathological injuries in mice challenged with high-fat diet (HFD) and streptozotocin (STZ). The glucose metabolism indicators and behavioral performance were detected. The mRNA expression of IL-1β, IL-6, TNF-α, ocln, zo-1, clnds and protein expression of APP, p-Tau, p-IRS1, p-AKT, p-ERK, TREM1/2 were measured. The fluorescence intensities of MAP-2, NeuN, APP, p-Tau, GFAP and IBA-1 were observed. The results showed that combination of HFD and STZ/I.P could induce glucose metabolic turmoil and Alzheimer's disease (AD)-like neuropsychiatric dysfunction in mice, as indicated by the increased concentrations of FBG and impaired learning and memory ability. Moreover, the model mice presented the increased level of APP, p-Tau, p-IRS1, TREM2, IL-1β, IL-6, TNF-α, ocln, zo-1 and clnds, the decreased level of p-AKT, p-ERK and TREM1, as well as the neuron damage and the hyperactivation of astrocytes and microglia in the hippocampus as compared with control mice. Only male mice were used in this study. Although AD and type 2 diabetes mellitus (T2DM) are distinct pathologies, our results suggested that combination of HFD and STZ/I.P. a widely used T2DM modeling method, could successfully induce AD-like behavioral impairments and neuropathological injuries in mice, the mechanism might be involved with neuroinflammation and its associated dysfunction of IRS1/AKT/ERK signaling pathway. Our findings further support the potential overlap between T2DM and AD pathophysiology, providing insight into the mechanisms underlying the comorbidity of these diseases.Significance Statement Alzheimer's disease (AD) is a progressive neurodegenerative disorder which prevalence is increasing with the rapidly growing global elderly population, but the accurate disease mechanisms and underlying therapeutic targets remains unclear. The aim of the present study is to investigate the behavioral performance changes and neuropathological injuries in mice challenged with the combination of a high-fat diet (HFD) and intraperitoneal injection of streptozotocin (STZ).In our study suggested that combination of HFD and STZ/I.P. could successfully induce AD-like behavioral impairments and neuropathological injuries in mice, which mechanism might be involved with neuroinflammation and its associated dysfunction of IRS1/AKT/ERK signaling pathway. Our findings further support the potential overlap between T2DM and AD pathophysiology, providing insight into the mechanisms underlying the comorbidity of these diseases.

Temporal changes of neurobehavior in rats following varied blast magnitudes and screening of serum biomarkers in early stage of brain injury

Blast neurotrauma has been linked to impairments in higher-order cognitive functions, including memory, attention, and mood. Current literature is limited to a single overpressure exposure or repeated exposures at the same level of overpressure. In this study, a rodent model of primary blast neurotrauma was employed to determine the pressure at which acute and chronic neurological alterations occurred. Three pressure magnitudes (low, moderate and high) were used to evaluate injury thresholds. A biology shock tube (BST) was used to simulate shock waves with overpressures of 60 kPa, 90 kPa and 120 kPa respectively. Neurological behavior of the rats was assessed by the Multi-Conditioning System (MCS) at 1 d, 7 d, 28 d and 90 d after shock wave exposure. Serum dopamine (DA), 5-hydroxytryptamine (5-HT), brain-derived neurotrophic factor (BDNF) and gamma-aminobutyric acid (GABA) were measured at the same time points. The proteomic analysis was conducted to identify potentially vulnerable cellular and molecule targets of serum in the immediate post-exposure period. Results revealed that: (1) Anxiety-like behavior increased significantly at 1 d post-exposure in the medium and high overpressure (90 kPa, 120 kPa) groups, returned to baseline at 7 days, and anxiety-like behavior in the high overpressure groups re-emerged at 28 d and 90 d. (2) High overpressure (120 kPa) impaired learning and memory in the immediate post-exposure period. (3) The serum DA levels decreased significantly at 1 d post-exposure in the medium and high overpressure groups; The 5-HT levels decreased significantly at 1 d and 90 d in the high overpressure groups; The BDNF levels decreased significantly at 90 d in the high overpressure groups. (4) Proteomic analysis identified 38, 306, and 57 differentially expressed proteins in serum following low, medium and high overpressure exposures, respectively. Two co-expressed proteins were validated. Functional analysis revealed significant enrichment of 1121, 2096, and 1121 Gene Ontology (GO) items and 33, 47, and 26 Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways, indicating extensive molecular responses to overpressure in the early phase. These findings suggest that exposure, even at moderate levels, can induce persistent neurobehavioral and molecular alterations, highlighting the need for further research into the long-term consequences of blast neurotrauma.

Domain-specific cognitive impairment is differentially affected by Alzheimer disease tau pathologic burden and spread

Abstract Tau pathology in Alzheimer disease (AD) is often evaluated in regions associated with episodic memory impairment. However, heterogeneous spreading patterns of tau are observed and correspond to impairment in different cognitive domains. We have previously developed a metric to quantify tau spread extent that is robustly sensitive to atypical spreading patterns. Here, we evaluate tau spread relative to domain-specific and general cognitive impairments during early stages of AD. 529 participants with baseline tau positron emission tomography (PET) and neuropsychological testing were separated into disease stage groups based on amyloid PET positivity and clinical status via CDR. General cognition was assessed using the Knight Preclinical Alzheimer Cognitive Composite (Knight PACC). Domain-specific composites were calculated for episodic memory, semantic memory, working memory, and attention/processing speed. Baseline tau burden, the average tau intensity across previously defined AD signature regions, and baseline tau spread extent, the proportion of the brain with elevated tau pathology, were quantified for each participant as Tau Index and Tau Spatial Spread respectively. Tau burden and tau spread were evaluated relative to baseline and longitudinal cognitive performance, as well as longitudinal clinical progression. Tau burden and tau spread extent both significantly correlate with cognitive impairment in symptomatic AD. Tau burden is most strongly correlated to episodic (r = -0.37, p = 0.02) and semantic (r = -0.36, p = 0.02) memory. In contrast, tau spread extent is most strongly correlated to the Knight PACC (r = -0.37, p = 0.01) and attention/processing speed (r = -0.44, p &amp;lt; 0.01), especially in preclinical AD (r = -0.27, p &amp;lt; 0.01). Tau burden captures more variance than tau spread extent in longitudinal change in the Knight PACC, episodic memory, semantic memory, attention/processing speed, and clinical progression. Tau burden strongly relates to baseline episodic and semantic memory, which may reflect that it is heavily weighted by entorhinal tau, a region previously linked to memory processing. In contrast, stronger associations between tau spread extent and baseline attention/processing speed could reflect the inclusion of additional brain regions, particularly the frontal lobe, which support a wider range of cognitive processing. Additionally, tau spread extent is generally more sensitive to baseline preclinical deficits, however tau burden better estimates future decline across all cognitive domains and clinical symptom onset. Together, these findings suggest complementary utility of evaluating both tau burden and tau spread extent in early AD progression.

Classifying cognitive impairment based on FDG-PET and combined T1-MRI and rs-fMRI: An ADNI study.

Mild cognitive impairment (MCI) refers to a memory impairment among non-demented adults. It is a condition that increases the risk of dementia, notably due to Alzheimer's disease (AD). MCI is heterogeneous and there is a need for novel diagnostic approaches. Fluorodeoxyglucose positron emission tomography (FDG-PET) imaging provides robust AD biomarker characteristics, while anatomical and functional magnetic resonance imaging (MRI) offer complementary information. Classify MCI and cognitively normal (CN) adults using FDG-PET images; predict individuals with MCI that convert to AD dementia; determine if MRI can achieve comparable performance to FDG-PET classification. Four ADNI cohorts were created. Cohort 1: 805 participants (MCI n = 455; CN n = 350) that underwent FDG-PET. FDG-PET images were inputs to a one-channel 3-dimensional (3D) DenseNet deep learning model. Cohort 2: 348 participants (MCI n = 174; CN n = 174) with MRI and functional MRI. Cohort 3: overlapping cases from cohorts 1 and 2 (MCI n = 70; CN n = 70). Cohort 4: 336 participants (MCI-converters n = 168; MCI-stable n = 168) with FDG-PET from cohort 1. The one/two-channel models' inputs were T1-weighted MRI and/or amplitude of low-frequency fluctuations images, with classification metrics evaluated through 10-fold cross-validation. The FDG-PET model achieved 88.02%±3.82 accuracy for MCI versus CN classification, with 88.70%±4.70 sensitivity and 87.14%±5.03 specificity. Neither MRI model outperformed the FDG-PET model, as the highest MRI-based accuracy was 76.86%±1.95. The FDG-PET model achieved 63.23%±4.68 accuracy in classifying MCI-converters versus MCI-stable. FDG-PET images produced the highest accuracy in classifying MCI versus CN. While MRI-based approaches were inferior to FDG-PET, multi-contrast MRI still offers value for neurodegeneration classification.

Long-term Administration of High-Dose Methylphenidate Impairs Spatial Memory and Induces Neurodegeneration in the Hippocampus

Background: Methylphenidate hydrochloride (MPH) is used as a first-line treatment for attention-deficit/hyperactivity disorder. Nonetheless, there are a few studies regarding the relationship between memory and hippocampal neuron changes following long-term MPH treatment. Objectives: This study aimed to investigate the effects of pathological changes on memory following long-term MPH treatment. Methods: Forty rats were randomly and equally divided into four groups based on dosages. Animals underwent 0.6, 2.5 (low doses), or 10 (high dose) mg/kg MPH or saline (control) per day for 28 days. The Morris water maze (MWM) test was conducted at two time points: Two hours and four weeks after initiating MPH administration. The two-hour test evaluated single dose effects of MPH on memory, while the four-week test assessed long-term administration of MPH effects on memory performance. Finally, the brains were removed and pathological alterations in the cornu ammonis (CA1) and dentate gyrus (DG) regions of the hippocampus were investigated. Results: Single-dose administration of 10 mg/kg MPH decreased the latency time in the MWM test, while long-term administration of MPH increased the latency time. Furthermore, histopathology results showed that MPH at doses of 2.5 mg/kg and 10 mg/kg significantly increased the percentage of neurodegeneration in both the CA1 and DG regions compared to controls. Conclusions: Our findings show that a high single dose of MPH improves memory in rats. However, long-term administration of high dose of MPH impaired memory; such impairment may be associated with the neurodegeneration in the pyramidal layer cell of the CA1 and the granular layer cell of the DG.

Constructing a Metal-Organic Frameworks-Based Long-Acting Sequential Release System for the Treatment of Alzheimer's Disease.

Due to the unclear pathogenesis of Alzheimer's disease (AD) and the lack of a completely cured medication, AD patients need to take medication in order and on time every day all one's life, which is difficult for severe memory impairment patients to strictly follow on time. Traditional AD drug carriers, such as sugar coating and capsules, rely on dissolution or fragmentation to achieve drug release, which lacks the interaction between drug molecules and carriers, thus they cannot achieve sufficient long-acting and sequential drug release. Herein, Mn-MOF-74, which ligand structure is similar to two antioxidants dihydroquercetin (DHQ) and resveratrol (Res) is chosen as the carrier. Due to the differences in adsorption energy between DHQ/MOF and Res/MOF, the release speed of DHQ is much faster than Res. Therefore, Mn-MOF-74 loaded with DHQ and Res (DR@MOF) showed sequential drug release and a long-term antioxidant effect for ≈72h, with an efficacy time six times longer than that of vitamin E. In 5×FAD transgenic mice, DR@MOF exhibited excellent capacity in maintaining oxidative balance in the brain, ameliorating spatial learning and memory deficits, and showed the potential of an AD agent for long-acting and sequential treatment.

The effects of crocin on fear condition memory impairment caused by morphine in relation to gene expression of amygdala HSP70, HSP90 and NF-kB

BackgroundSome studies have shown that morphine causes memory impairment through different mechanisms. The roles of inflammation/NF-κB and BDNF/TrkB/CREB pathways are significant in the memory deficits caused by morphine. Aim: In this study, the effect of crocin on the impairment of fear memory caused by morphine was investigated, and the expression of HSP70, HSP90, and NF-kB genes that play an important role in memory in male Wistar rats was measured. Material and methodThe fear conditioning test was used to check the fear memory of rats, and total Freezing time was considered as an index of memory. Rats (96 Wistar rats) were randomly divided into 12 groups. The rats were injected with saline (1 ml/kg) or different doses of morphine (0.5, 2.5, and 5 mg/kg) 5 min after injection of saline (1 ml/kg) or subthreshold doses of crocin (60 mg/kg). Real-time PCR method was used for HSP70, HSP90, and NF-kB gene expression in the Amygdala. ResultAdministration of morphine 5 mg/kg decreased the total freezing and increased the latency freezing (P < 0.001). Also, the results showed that crocin 60 mg/kg reduced memory impairment induced by morphine. Real-time PCR analysis showed that morphine 5 mg/kg significantly increased the expression of the HSP70, HSP90, and NF-kB genes. However, the subthreshold dose of crocin (60 mg/kg) reduced the increase in gene expression. ConclusionThe study showed that morphine impacts memory and boosts gene expression of HSP70, HSP90, and NF-kB, while crocin could potentially reverse this effect by regulating these amygdala genes, suggesting avenues for future research.

Amelioration of Neurochemical Alteration and Memory and Depressive Behavior in Sepsis by Allopurinol, a Tryptophan 2,3-Dioxygenase Inhibitor.

In response to inflammation and other stressors, tryptophan is catalyzed by Tryptophan 2,3-Dioxygenase (TDO), which leads to activation of the kynurenine pathway. Sepsis is a serious condition in which the body responds improperly to an infection, and the brain is the inflammation target in this condition. This study aimed to determine if the induction of TDO contributes to the permeability of the Blood-Brain Barrier (BBB), mortality, neuroinflammation, oxidative stress, and mitochondrial dysfunction, besides long-term behavioral alterations in a preclinical model of sepsis. Male Wistar rats with two months of age were submitted to the sepsis model using Cecal Ligation and Perforation (CLP). The rats received allopurinol (Allo, 20 mg/kg, gavage), a TDO inhibitor, or a vehicle once a day for seven days. Sepsis induction increased BBB permeability, IL-6 level, neutrophil infiltrate, nitric oxide formation, and oxidative stress, resulting in energy impairment in 24h after CLP and Allo administration restored these parameters. Regarding memory, Allo restored short-term memory impairment and decreased depressive behavior. However, no change in survival rate was verified. In summary, TDO inhibition effectively prevented depressive behavior and memory impairment 10 days after CLP by reducing acute BBB permeability, neuroinflammation, oxidative stress, and mitochondrial alteration.

A preclinical and phase I clinical study of ex vivo-expanded amyloid beta-specific human regulatory T cells in Alzheimer’s disease

IntroductionDespite advancements in adoptive regulatory T cell (Treg) therapy, its application in Alzheimer’s disease (AD) remains constrained by challenges in ex vivo Treg selection and expansion with antigen specificity. Our previous findings demonstrated the bystander suppressive immunomodulatory mechanism of ex vivo expanded amyloid β-specific mouse Tregs in AD models, prompting inquiry into the efficacy of ex vivo expanded human Tregs in AD. MethodsWe developed an effective ex vivo expansion method for manufacturing amyloid β-specific human Tregs (Aβ-hTreg) and evaluated their safety and efficacy in 3xTg mouse models of AD and a phase 1 clinical trial with six AD patients. The phenotype of Aβ-hTreg was analyzed using single-cell transcriptomics. The clinical trial involved intravenous administration of Aβ-hTreg, with three patients receiving a low dose and three receiving a high dose. Exploratory assessments of effectiveness, including cognitive tasks and functional evaluations, were conducted ninety days post-treatment. ResultsBehavioral spatial learning and memory impairment, neuroinflammatory and amyloid pathology were dramatically ameliorated by single intrathecal administration of ex vivo expanded Aβ−hTreg to 3xTg AD mice. Single cell transcriptomics analysis revealed alterations in five key genes within a cluster of Tregs under antigen-specific manufacturing conditions. In the clinical trial with six AD patients, dose-limiting toxicity was experienced by none of the participants within five days of receiving GMP-grade Aβ-hTreg (VT301), indicating its good tolerability. Although exploratory assessments of effectiveness did not reach statistically significant values among the groups, these findings offer valuable insights for AD treatment and management, guiding the planning of the next phase of clinical trials. DiscussionThis study suggests that hTregs may modulate Alzheimer's disease pathology by suppressing neuroinflammation, while VT301 shows promise as a safe treatment option. However, further research is necessary to confirm its clinical efficacy and optimize treatment strategies. Trial registrationTitle: A Study of Possibility of Using Regulatory T Cells (VT301) for Treatment of Alzheimer's Disease, ClinicalTrials.gov NCT05016427, Study approval date: Ministry of Food and Drug Safety of the Republic of Korea (MFDS) - August 31st, 2020, Institutional Review Board (IRB) of Seoul National University Hospital, Republic of Korea - September 29th, 2020, The date of first patient enrollment: December 7th, 2020. https://clinicaltrials.gov/study/NCT05016427

Temporal differential effects of post-injury alcohol consumption in a mouse model of blast-induced traumatic brain injury

Traumatic brain injury is a prevalent condition that affects millions worldwide with no clear understanding or effective therapeutic management available. Military soldiers have a high risk of exposure to blast-induced traumatic brain injury (bTBI). Furthermore, alcohol drinking is common in this population, and studies have shown that post-TBI alcohol exposure can result in memory loss. Hence, it is possible that alcohol could contribute to the overall pathological outcome of brain trauma. However, such a possibility has not been explored in detail. Here, we combined a mild bTBI (mbTBI) model with the drinking-in-the-dark (DID) paradigm to investigate the pathological synergy between mbTBI and alcohol consumption by examining brain oxidative stress levels and behavioral alterations in mice. The results revealed the anxiolytic and short-term memory improvement effects of post-trauma alcohol drinking examined at an early timepoint post mbTBI. However, extended alcohol drinking for up to three weeks post mbTBI impaired long-term memory and was accompanied by intensified oxidative stress in brain regions associated with memory and anxiety. These findings, as well as those from previous in vitro TBI/alcohol studies, suggest a pathological synergy of physical force and post-impact alcohol exposure. This knowledge could potentially aid in establishing guidelines for TBI victims to avoid further injury to their brains as well as to help maximize their recovery following TBI.

Activation of spleen tyrosine kinase (SYK) contributes to neuronal pyroptosis and cognitive impairment in diabetic mice via the NLRP3/Caspase-1/GSDMD signaling pathway.

Diabetes mellitus (DM) patients are at increased risk of cognitive impairment. The precise mechanisms underlying the association between DM and cognitive impairment remain unclear. Spleen tyrosine kinase (SYK), a crucial regulator of signal transduction, has been implicated in microglial pyroptosis in experimental ischemic stroke models. The present study investigated the potential role of SYK in DM-associated cognitive impairment. Diabetes was induced by streptozotocin (STZ) in C57BL/6 mice, and cognitive function and cerebral injury were assessed 12weeks later using the Morris water maze (MWM), TUNEL assay and Western blotting. In vitro, the inhibition of SYK was investigated in a mouse hippocampal neuronal cell line cultured with high glucose. Compared with control mice, DM mice presented impaired spatial learning and memory. Additionally, SYK activation was linked to neuronal pyroptosis, as evidenced by increases in the number of TUNEL-positive cells and protein levels of NLRP3, ASC, procaspase-1, caspase-1, GSDMD, the GSDMD N-terminal fragment, pro-IL-1β, and IL-1β in the hippocampus of DM mice. Compared with no treatment, SYK knockdown markedly attenuated cognitive impairment and histologic and ultrastructural pathological changes in the hippocampus of DM mice. The increased expression of pyroptosis-associated proteins and the increased number of TUNEL-positive cells were also significantly reduced. In vitro, high glucose significantly activated SYK to trigger the canonical pyroptotic pathway in cultured HT22 cells. The inhibition of SYK with a small interfering RNA or specific inhibitor significantly ameliorated the neuronal pyroptosis mediated by high glucose. Our findings demonstrate that SYK activation plays a pivotal role in promoting the cognitive impairment associated with DM. This effect is mediated by triggering neuronal pyroptosis through the canonical NLRP3/Caspase-1/GSDMD pathway. These results suggest that SYK may serve as a potential target for preventing or mitigating cognitive impairment in patients with DM.

Late-Life Alcohol Exposure Does Not Exacerbate Age-Dependent Reductions in Mouse Spatial Memory and Brain TFEB Activity

Alcohol consumption is believed to affect Alzheimer’s disease (AD) risk, but the contributing mechanisms are not well understood. A potential mediator of the proposed alcohol-AD connection is autophagy, a degradation pathway that maintains organelle and protein homeostasis. Autophagy is regulated through the activity of Transcription factor EB (TFEB), which promotes lysosome and autophagy-related gene expression. The purpose of this study is to explore whether chronic alcohol consumption worsens the age-related decline in TFEB-mediated lysosomal biogenesis in the brain and exacerbates cognitive decline associated with aging. To explore the effect of alcohol on brain TFEB and autophagy, we exposed young (3-month-old) and aged (23-month-old) mice to two alcohol-feeding paradigms and assessed biochemical, transcriptome, histology, and behavioral endpoints. In young mice, alcohol decreased hippocampal nuclear TFEB staining but increased SQSTM1/p62, LC3-II, ubiquitinated proteins, and phosphorylated Tau. Hippocampal TFEB activity was lower in aged mice than it was in young mice, and Gao-binge alcohol feeding did not worsen the age-related reduction in TFEB activity. Morris Water and Barnes Maze spatial memory tasks were used to characterize the effects of aging and chronic alcohol exposure (mice fed alcohol for 4 weeks). The aged mice showed worse spatial memory acquisition in both tests. Alcohol feeding slightly impaired spatial memory in the young mice, but had little effect or even slightly improved spatial memory acquisition in the aged mice. In conclusion, aging produces greater reductions in brain autophagy flux and impairment of spatial memory than alcohol consumption.

Disrupted working memory event-related network dynamics in multiple sclerosis

In multiple sclerosis (MS), working memory (WM) impairment can occur soon after disease onset and significantly affects the patient’s quality of life. Functional imaging research in MS aims to investigate the neurophysiological underpinnings of WM impairment. In this context, we utilize a data-driven technique, the time delay embedded-hidden Markov model, to extract spectrally defined functional networks in magnetoencephalographic (MEG) data acquired during a WM visual-verbal n-back task. Here, we show that the activation of two networks is altered in relapsing remitting-MS patients. First, the activation of an early theta prefrontal network linked to stimulus encoding and attentional control significantly decreases in MS compared to HC. This diminished activation correlates with reduced accuracy and higher reaction time, suggesting that impaired attention control impacts task performance in MS patients. Secondly, a frontoparietal network characterized by beta coupling is activated between 300 and 600 ms post-stimulus, resembling the event-related P300, a cognitive marker extensively explored in EEG studies. The activation of this network is amplified in patients treated with benzodiazepine, in line with the well-known benzodiazepine-induced beta enhancement. Altogether, the TDE-HMM technique extracts task-relevant functional networks showing disease-specific and treatment-related alterations, revealing potential new markers to assess and track WM impairment in MS.