Inhibiting the microglia activation improves the spatial memory and adult neurogenesis in rat hippocampus during 48 h of sleep deprivation

Sex differences in reward-based operant conditioning performance and neurotransmitter changes following chronic sleep restriction stress in rats

BACKGROUND

Sleep deprivation significantly impairs cognitive function, which disrupts daily life. However, sex differences in these impairments are not well understood, as most preclinical studies primarily use male animals, neglecting potential differences between sexes. This study aims to investigate sex-specific differences in cognitive function under sleep deprivation using reward-based operant conditioning tasks.

RESULTS

Sprague-Dawley rats were pre-trained on a lever-press task and subsequently divided into control and chronic sleep restriction (CSR) groups. The CSR group underwent 14 days of sleep restriction. After CSR modeling, rats were assessed using the open field test, retraining on the lever-pressing task, signal discrimination task, and extinction task to evaluate motor abilities, memory formation, learning, and cognitive flexibility. CSR significantly impaired task performance in both sexes, with rats requiring more time and exhibiting lower accuracy. In the signal discrimination task, male rats showed longer feeding latency and lower accuracy compared to females. CSR also specifically increased the frequency of operant responses in male rats. In the extinction task, CSR enhanced exploration time and frequency in both sexes, with females exhibiting significantly higher exploration frequencies than males. Biochemically, CSR induced sex-specific alterations, including elevated serum MDA and MAO levels in males and increased serotonin, dopamine, and epinephrine in both sexes. Although activation was observed in metabolites of the tryptophan-kynurenine pathway, sex differences were evident in the kynurenic acid metabolism levels in the prefrontal cortex.

CONCLUSIONS

CSR impairs cognitive function in both male and female rats, with significant sex differences observed. Male CSR rats exhibited impaired signal discrimination, while CSR impaired extinction learning in female rats. These impairments are accompanied by CSR-induced oxidative stress, neurotransmitter dysregulation, and disturbances in the tryptophan metabolic pathway. These findings underscore the importance of considering sex differences in understanding the effects of sleep deprivation on cognitive function and developing targeted intervention strategies.

Running to remember: The effects of exercise on perineuronal nets, microglia, and hippocampal angiogenesis in female and male mice

Exercise is accepted as a positive health behaviour; however, the mechanisms of exercise on neuroprotection and cognitive health are not completely understood. The purpose of this study was to explore the neurobiological benefits of chronic treadmill exercise in female and male mice through its role in microglial content and morphology, cerebral vascularization, and perineuronal net (PNN) expression. We further examined how these neurobiological changes relate to spatial memory outcomes. Adult mice were assigned to a sedentary or treadmill exercise group for eight weeks. During the final week, all mice were trained on a spatial memory task (Barnes maze) and brains were collected for immunohistochemistry. Exercised mice made fewer errors than sedentary mice during the first two days of training and probe trial. Females, regardless of exercise training, made fewer errors during Barnes maze training and demonstrated a greater frequency of spatial strategy use compared to males. Exercised mice, regardless of sex, had fewer PNNs in the dentate gyrus of the hippocampus compared to sedentary controls. The number of PNNs in the dorsal dentate gyrus was positively correlated with total errors during training. During the probe, greater errors correlated with more PNNs among the exercised group only. Microglia count and cerebral vascularization were not affected by exercise, although proportions of microglia type (ameboid, stout/thick, and thick/thin) were regulated by exercise in the ventral dentate gyrus. We conclude that exercise decreases PNNs in the dentate gyrus in both sexes and this may be related to better spatial learning and memory.

Could sleep be a brain/cognitive/neural reserve-builder factor? A systematic review on the cognitive effects of sleep modulation in animal models

The brain/cognitive/neural reserve concept suggests that lifelong experiences, from early life through adulthood, make the brain more resilient to neuronal damage. Modifiable lifestyle factors, such as sleep, can support the development and enhance such a reserve, helping to counteract age- or disease-related brain changes and their impact on cognition. Sleep plays a crucial role in cognitive functioning, and disruptions or disorders may increase neurodegenerative risks. This systematic review aims to explore how functional and disturbed sleep impacts cognitive functions and neuromorphological mechanisms in rodents, aiming to better understand its role in brain/cognitive/neural reserve development. This systematic review, registered on PROSPERO (ID: CRD42023423901) and conducted according to PRISMA-P guidelines, searched PubMed, Scopus, Web of Science, and Embase databases for studies up to June 2022, with terms related to sleep, rodents, and cognitive functions. Of the 28,666 articles identified, 142 met the inclusion criteria. Main results showed significant cognitive decline after sleep deprivation, especially in memory performance. These findings supports the importance of sleep as a critical factor in modulating brain/cognitive/neural reserve.

Causal associations between sleep traits, sleep disorders, and glioblastoma: a two-sample bidirectional Mendelian randomization study

Glioblastoma (GBM), a highly aggressive brain tumor predominantly affecting individuals over 40, often co-occurs with sleep disorders. However, the causal relationship remains unclear. This study employed a bidirectional Mendelian randomization (MR) approach to investigate the causal links between sleep traits/disorders and GBM. Sleep trait and disorder data were obtained from the IEU Open GWAS Project, while GBM data came from the Finn cohort. Primary analysis utilized the inverse-variance weighted (IVW) method, complemented by MR-Egger, weighted median, and weighted mode methods. MR pleiotropy residual sum and outlier (MR-PRESSO) was applied to detect potential outliers, and MR-Egger regression explored horizontal pleiotropy, with Cochran's Q test assessing heterogeneity. IVW analysis indicated a significant negative association between sleep duration and GBM risk [odds ratio (OR) = 0.13; 95% confidence interval (CI) = 0.02-0.80; P = 0.027). Conversely, GBM was positively associated with evening chronotype (OR = 1.0094; 95% CI = 1.0034-1.0154; P = 0.002). No significant associations were found for other sleep traits or disorders. Midday napping showed potential pleiotropy, and significant heterogeneity was noted in the reverse analysis. MR-PRESSO identified no outliers. Shorter sleep duration may elevate GBM risk, and GBM might influence circadian preference toward eveningness. Further studies are warranted to validate these findings.NEW & NOTEWORTHY This study employs a bidirectional Mendelian randomization approach to explore the causal relationship between various sleep traits, sleep disorders, and glioblastoma (GBM). We found that shorter sleep duration may increase GBM risk, while GBM may shift individuals toward an evening chronotype. No significant relationships were observed for other sleep traits or any of the sleep disorders. These findings illuminate the complex interplay between sleep and GBM, highlighting the need for further investigation into their correlations.

WuYou decoction effectively reduces neuronal damage, synaptic dysfunction, and Aβ production in rats exposed to chronic sleep deprivation by modulating the Aβ-related enzymes and SIRT1/Nrf2/NF-κB pathway

ETHNOPHARMACOLOGICAL RELEVANCE

Chronic sleep deprivation (CSD) can result in neuronal damage, synaptic dysfunction, Aβ production, neuroinflammation, and ultimately cognitive deterioration. WuYou Decoction (WYD), a contemporary prescription, has shown promise in enhancing sleep quality and cognitive performance in individuals with insomnia. However, the specific molecular mechanisms responsible for the neuroprotective effects of WYD on CSD remain incompletely understood.

AIM OF THE STUDY

This study aimed to investigate the neuroprotective effects of WYD on the CSD model and its molecular mechanism.

MATERIALS AND METHODS

UHPLC-MS/MS analysis was utilized to analyze the active ingredients of WYD extract. The study employed the multi-platform water environment method to establish the CSD model in rats. Subsequent to treatment with varying doses of WYD in CSD rats, cognitive function and pathological alterations in hippocampus and cortex, including neuronal damage, synaptic dysfunction, Aβ production, and neuroinflammation, were evaluated through a combination of Morris Water Maze test, HE staining, Nissl staining, Golgi-Cox staining, Transmission electron microscope, ELISA, Immunohistochemistry staining, Immunofluorescence staining and Western blot.

RESULTS

UHPLC-MS/MS analysis revealed a total of 99 active ingredients were identified from the WYD extract. The administration of WYD exhibited a mitigation of cognitive decline in the model of CSD, as evidenced by increased neuron count in the hippocampus and cortex, and improved density and length of dendritic spines in these brain regions. Furthermore, WYD was found to suppress the Aβ production, and inhibit the expression of BACE1, PS1, GFAP, IBA1, IL-1β, IL-6, TNF-α, phosphorylated IκBα (Ser32) and phosphorylated NF-κB p65 (Ser536) in the hippocampus and cortex, while also increasing the levels of PSD95, SYN1, ADAM10, IDE, SIRT1 and Nrf2.

CONCLUSIONS

WYD exhibits neuroprotective properties in CSD, potentially through modulation of the Aβ-related enzymes and SIRT1/Nrf2/NF-κB pathway.

Exploring β-caryophyllene: a non-psychotropic cannabinoid's potential in mitigating cognitive impairment induced by sleep deprivation

Sleep deprivation or sleep loss, a prevalent issue in modern society, is linked to cognitive impairment, leading to heightened risks of errors and accidents. Chronic sleep deprivation affects various cognitive functions, including memory, attention, and decision-making, and is associated with an increased risk of neurodegenerative diseases, cardiovascular issues, and metabolic disorders. This review examines the potential of β-caryophyllene, a dietary non-psychotropic cannabinoid, and FDA-approved flavoring agent, as a therapeutic solution for sleep loss-induced cognitive impairment. It highlights β-caryophyllene's ability to mitigate key contributors to sleep loss-induced cognitive impairment, such as inflammation, oxidative stress, neuronal death, and reduced neuroplasticity, by modulating various signaling pathways, including TLR4/NF-κB/NLRP3, MAPK, Nrf2/HO-1, PI3K/Akt, and cAMP/PKA/CREB. As a naturally occurring, non-psychotropic compound with low toxicity, β-caryophyllene emerges as a promising candidate for further investigation. The review underscores the therapeutic potential of β-caryophyllene for sleep loss-induced cognitive impairment and provides mechanistic insights into its action on crucial pathways, suggesting that β-caryophyllene could be a valuable addition to strategies aimed at combating cognitive impairment and other health issues due to sleep loss.

Insufficient Sleep and Alzheimer's Disease: Potential Approach for Therapeutic Treatment Methods

The interaction between Alzheimer's disease (AD) and sleep deprivation has recently gained attention in the scientific literature, and recent advances suggest that AD epidemiology management should coincide with the management of sleeping disorders. This review focuses on the aspects of the mechanisms underlying the link between AD and insufficient sleep with progressing age. We also provide information which could serve as evidence for future treatments of AD from the early stages in connection with sleep disorder medication.

Protective effects of licofelone on scopolamine-induced spatial learning and memory impairment by enhancing parkin-dependent mitophagy and promotion of neural regeneration and in adult mice

Inhibition of COX and LOX could contribute to memory formation and prevention of neurodegeneration, by alleviation of neuroinflammation and improvement of mitochondrial homeostasis. We aimed to assess the effect of licofelone, a dual COX and 5-LOX inhibitor on memory formation, neural apoptosis, neural regeneration, and mitophagy in acute and chronic dosages, given that licofelone could regulate nitric oxide levels. Y-maze and Passive Avoidance tests were used to evaluate memory function in NMRI mice using the EthoVision setting, following scopolamine administration (1 mg/kg, i.p.) as an acute amnestic drug. Hippocampi were used to evaluate the levels of apoptosis via TUNEL assay, neural regeneration via immunohistochemistry method detecting doublecortin and nestin, and mitophagy via Western blot of mitophagy proteins Parkin and ATG5. While acute high-dose licofelone (20 mg/kg) could reverse amnestic effects of scopolamine in passive avoidance test (p = 0.0001), Chronic licofelone (10 mg/kg for 10 consecutive days) could improve performance in Y-maze (p = 0.0007). Molecular analysis revealed that the chronic form of the drug could enhance neural regeneration in CA1 and SGZ regions, reset mitophagy levels as much as the healthy state, and reduce apoptosis rate. Licofelone appears to show a desirable anti-amnestic profile in a low dose chronically; it is hence recommended for future clinical studies on the prevention of neuroinflammation and memory deficit.

Forget me not: The effect of doxycycline on human declarative memory

Investigations into neuroprotective drugs are in high demand for the treatment of neurodegenerative diseases, such as multiple sclerosis or Alzheimer's disease, but also psychiatric disorders, such as depression, trauma, and substance use. One potential drug class being investigated are tetracyclines impacting on a variety of neuroprotective mechanisms. At the same time, tetracyclines like doxycycline have been suggested to affect human fear and spatial memory as well as reducing declarative memory retention. Based on the assumed necessity for synaptic consolidation in hippocampus-dependent learning, we hypothesised declarative memory may be similarly impaired by doxycycline as fear and spatial memory. Therefore, in this study we investigate the potential diminishing effects of doxycycline on consolidation of declarative memory in healthy humans. Additionally, to test for effect specificity we assessed motor memory, sustained attention, and processing speed. We administered a neuropsychological test battery in three independent randomized placebo-controlled double-blind trials (RCTs), in which healthy young volunteers (total N = 252) either received a single oral dose doxycycline (200 mg, n = 126) or placebo (n = 126) in a between-subject design. We found no evidence for a detrimental effect of doxycycline on declarative memory; instead, doxycycline improved declarative learning (p-value=0.022, Cohen's d=0.15) and memory consolidation (p=0.040, d=0.26). Contrarily, doxycycline slightly reduced motor learning (p=0.001, d=0.10) but subtly strengthened long-term motor memory (p=0.001, d=0.10). These results suggest that doxycycline can improve declarative learning and memory without having long term negative effects on other cognitive domains in healthy humans. Our results give hope to further investigate doxycycline in neuroprotective treatment applications.

Phloretin alleviates sleep deprivation-induced cognitive impairment by reducing inflammation through PPARγ/NF-κB signaling pathway

Sleep loss leads to significant pathophysiological consequences, including cognitive impairment. The neuroinflammation are pivotal factors in the pathogenesis of cognitive impairment induced by sleep loss. The phloretin (PHL), derived from peel of juicy fruits, has demonstrated potent anti-inflammatory properties. However, the precise influence of PHL on the cognitive impairment triggered by sleep loss and its underlying mechanism remain uncertain. In the present study, mice were subjected to sleep deprivation (SD) paradigm. Cognitive impairment induced by SD were significantly relieved by administration of PHL in a dose-dependent manner. Furthermore, PHL not only mitigated the synaptic losses but also enhanced dendritic spine density and neuronal activity within mice hippocampus following exposure to SD. Moreover, PHL treatment decreased the microglial numbers and altered microglial morphology in the hippocampus to restore the M1/M2 balances; these effects were accompanied by regulation of pro-/anti-inflammatory cytokine production and secretion in SD-exposed mice. Additionally, in vivo and in vitro studies showed PHL might attenuate the inflammation through the PPARγ/NF-κB pathway. Our findings suggest that PHL exerts inhibitory effects on microglia-mediated neuroinflammation, thereby providing protection against cognitive impairment induced by SD through a PPAR-γ dependent mechanism. The results indicate PHL is expected to provide a valuable candidate for new drug development for SD-induced cognitive impairment in the future.

Alterations in hippocampal somatostatin interneurons, GABAergic metabolism, and ASL perfusion in an aged male mouse model of POCD aggravated by sleep fragmentation

Sleep fragmentation (SF) is increasingly recognized as a contributing factor to postoperative cognitive dysfunction (POCD). Given the critical roles of somatostatin (SST) interneurons, associated gamma-aminobutyric acid (GABA)ergic neurotransmitters, and hippocampal perfusion in sleep-related cognition, this study examined changes in these mechanisms in preoperative SF affecting POCD induced by anesthesia/surgery in aged male mice. The Morris water maze (MWM), novel object recognition (NOR), and Y maze tests were utilized to evaluate POCD. Arterial spin labeling (ASL) was employed to measure hippocampal regional cerebral blood flow (rCBF). In vitro assays quantified the levels of GABAergic metabolites-such as SST, neuropeptide Y (NPY), glutamic acid decarboxylase 1 (GAD1), vesicular GABA transporter (VGAT), and GABA and the distribution of SST interneurons in the hippocampus through enzyme-linked immunosorbent assay and immunofluorescence. Preoperative 24-h SF exacerbated anesthesia/surgery-induced spatial memory impairments observed in the MWM, NOR, and Y maze tests. Preoperative 24-h SF significantly increased the number of SST interneurons in hippocampal CA1, elevated hippocampal levels of SST, NPY, GAD1, and GABA, and reduced the rCBF. Preoperative SF aggravated POCD in aged male mice, with an increased number of SST interneurons in hippocampal CA1, elevated hippocampal GABAergic metabolites, and a further reduction in rCBF.

Adolescent social isolation decreases colonic goblet cells and impairs spatial cognition through the reduction of cystine

Negative experiences during adolescence, such as social isolation (SI), bullying, and abuse, increase the risk of psychiatric diseases in adulthood. However, the pathogenesis of psychiatric diseases induced by these factors remain poorly understood. In adolescents, stress affects the intestinal homeostasis in the gut-brain axis. This study determined whether adolescent SI induces behavioral abnormalities by disrupting colonic function. Adolescent mice exposed to SI exhibit spatial cognitive deficits and microglial activation in the hippocampus (HIP). SI decreased the differentiation of mucin-producing goblet cells, which was accompanied by alterations in the composition of the gut microbiota, particularly the depletion of mucin-feeding bacteria. Treatment with rebamipide, which promotes goblet cell differentiation in the colon, attenuated SI-induced spatial cognitive deficits and microglial activation in the HIP and decreased cystine, a downstream metabolite of homocysteine. Treatment with cystine ameliorated SI-induced spatial cognitive deficits and increased microglial C-C motif chemokine ligand 7 (CCL7) levels in the HIP. Inhibition of CCL7 receptors by antagonists of CC motif chemokine receptors 2 (CCR2) and 3 (CCR3) in the HIP prevented spatial cognitive deficits induced by SI. Infusion of CCL7 into the HIP following microglial ablation with clodronate liposome induced spatial cognitive deficits. These findings suggest that adolescent SI decreases serum cystine levels by damaging the colonic goblet cells, resulting in spatial cognitive deficits by triggering microglial activation in the HIP. Our results indicate that increased CCL7 expression in hippocampal microglia may contribute to spatial cognitive deficits by activating CCR2 and CCR3.

Continuous Theta Burst Stimulation Inhibits Oxidative Stress-Induced Inflammation and Autophagy in Hippocampal Neurons by Activating Glutathione Synthesis Pathway, Improving Cognitive Impairment in Sleep-Deprived Mice

Sleep deprivation (SD) has been reported to have a negative impact on cognitive function. Continuous theta burst stimulation (cTBS) shows certain effects in improving sleep and neurological diseases, and its molecular or cellular role in SD-induced cognition impairment still need further exploration. In this study, C57BL/6 mice were subjected to 48 h of SD and cTBS treatment, and cTBS treatment significantly improved SD-triggered impairment of spatial learning and memory abilities in mice. Additionally, cTBS reduced malondialdehyde levels, increased superoxide dismutase activities, and inhibited the production of inflammatory cytokines, alleviating oxidative stress and inflammation levels in hippocampal tissues of SD model mice. cTBS decreased LC3II/LC3I ratio, Beclin1 protein levels, and LC3B puncta intensity, and elevated p62 protein levels to suppress excessive autophagy in hippocampal tissues of SD-stimulated mice. Then, we proved that inhibiting oxidative stress alleviated inflammation, autophagy, and death of hippocampal neuron cells through an in vitro cellular model for oxidative stress, and cTBS treatment promoted the production of glutathione (GSH), the nuclear translocation of nuclear factor erythroid 2-related factor 2 (Nrf2) and the mRNA expression of GSH synthesis-related genes to enhance antioxidant capacity in hippocampal tissues of SD mice. An Nrf2 inhibitor ML385 or a GSH synthesis inhibitor BSO reversed the alleviating effects of cTBS treatment on oxidative stress-associated damage of hippocampal tissues and cognitive impairment in SD model mice. Altogether, our study demonstrated that cTBS mitigates oxidative stress-associated inflammation and autophagy through activating the Nrf2-mediated GSH synthesis pathway, improving cognitive impairment in SD mice.

Blocking Brain Myeloid Differentiation Factor 2-Toll-like Receptor 4 Signaling Improves Cognition by Diminishing Brain Pathologies and Preserving Adult Hippocampal Neurogenesis in Obese Rats

The myeloid differentiation factor 2 (MD-2)-toll-like receptor 4 (TLR4) signaling pathway has been linked to cognitive decline in obese rats. However, more research is required to fully understand the mechanistic role of MD-2-TLR4 signalling pathway in obese-related cognitive impairment. In this study, we used two novel MD-2 inhibitors-MAC28 (a mono-carbonyl analogue of curcumin 28) and 2i-10 (a cinnamamide-derivative compound)-to better comprehend the mechanistic role of the MD-2-TLR4 signalling pathway in obese-related cognitive impairment. A normal diet (ND) (n = 16) and a high-fat diet (HFD) (n = 64) were given to randomly divided groups of male Wistar rats for 16-weeks. At week 13, 2 types of vehicles were randomly administered to ND-fed and HFD-fed rats, whereas MAC28 (3-doses) and 2i-10 (3-doses) were randomly given to HFD-fed rats until week 16. HFD-fed rats developed obesity with metabolic disturbances, a variety of brain pathologies and cognitive decline. In obese rats, blocking the brain MD-2-TLR4 signalling pathway with MAC28 or 2i-10 improved cognition via reducing brain inflammation, neurodegeneration, microglial activation, dendritic spine loss, brain oxidative stress, as well as preserving adult hippocampal neurogenesis. Our findings highlight to better understand the role of MD-2-TLR4 signaling pathway in obese-related cognitive decline, and MD-2 could be a potential therapeutic target for brain pathologies and cognitive decline in obesity.

Alzheimer's disease and sleep disorders: A bidirectional relationship

Alzheimer's disease (AD) is the most prevalent dementia, pathologically featuring abnormal accumulation of amyloid-β (Aβ) and hyperphosphorylated tau, while sleep, divided into rapid eye movement sleep (REM) and nonrapid eye movement sleep (NREM), plays a key role in consolidating social and spatial memory. Emerging evidence has revealed that sleep disorders such as circadian disturbances and disruption of neuronal rhythm activity are considered as both candidate risks and consequence of AD, suggesting a bidirectional relationship between sleep and AD. This review will firstly grasp basic knowledge of AD pathogenesis, then highlight macrostructural and microstructural alteration of sleep along with AD progression, explain the interaction between accumulation of Aβ and hyperphosphorylated tau, which are two critical neuropathological processes of AD, as well as neuroinflammation and sleep, and finally introduce several methods of sleep enhancement as strategies to reduce AD-associated neuropathology. Although theories about the bidirectional relationship and relevant therapeutic methods in mice have been well developed in recent years, the knowledge in human is still limited. More studies on how to effectively ameliorate AD pathology in patients by sleep enhancement and what specific roles of sleep play in AD are needed.

Geraniol (GER) attenuated chronic sleep restriction (CSR)-induced neuroinflammation in adolescent mice

Sleep insufficiency is a significant health problem worldwide, and adolescent sleep restriction (SR) could induce multiple neurodevelopmental disorders in the central nervous system (CNS). Microglial-mediated neuroinflammation plays a vital role in multiple neurological diseases, and recent research showed the regulation effect of immunoproteasome on microglia functions. Geraniol (GER), an important ingredient in many essential oils, possesses diverse pharmacological properties like anti-inflammatory and antioxidant. The present study was designed to evaluate the neuroprotective effect of GER on SR in adolescent mice and further investigate the underlying mechanisms. Our results displayed that 14 days of chronic sleep restriction (CSR) induced cognitive decline, and anxiety-like and attention-deficit behaviors, which were mitigated by GER pretreatment. GER administration also reversed microglial pro-inflammatory response under CSR stimulation in the anterior cingulate cortex (ACC) regions by reducing the expression and secretion of cytokines like IL-1β and TNF-α. Mechanism research showed that LMP7 mRNA was selectively up-regulated under CSR treatment but down-regulated by GER administration. Proteasome activity and protein expression of LMP7 were consistent with mRNA data. ONX-0914 was applied to inhibit LMP7 selectively, and data validated that GER might alleviate CSR-induced neuroinflammation by regulating LMP7. Our study provides evidence that LMP7 is a critical regulator of CSR-induced proinflammation, and geraniol might be a promising therapy against CSR-induced neurodevelopmental disorders.

Interplay between microglia and environmental risk factors in Alzheimer's disease

Alzheimer's disease, among the most common neurodegenerative disorders, is characterized by progressive cognitive impairment. At present, the Alzheimer's disease main risk remains genetic risks, but major environmental factors are increasingly shown to impact Alzheimer's disease development and progression. Microglia, the most important brain immune cells, play a central role in Alzheimer's disease pathogenesis and are considered environmental and lifestyle "sensors." Factors like environmental pollution and modern lifestyles (e.g., chronic stress, poor dietary habits, sleep, and circadian rhythm disorders) can cause neuroinflammatory responses that lead to cognitive impairment via microglial functioning and phenotypic regulation. However, the specific mechanisms underlying interactions among these factors and microglia in Alzheimer's disease are unclear. Herein, we: discuss the biological effects of air pollution, chronic stress, gut microbiota, sleep patterns, physical exercise, cigarette smoking, and caffeine consumption on microglia; consider how unhealthy lifestyle factors influence individual susceptibility to Alzheimer's disease; and present the neuroprotective effects of a healthy lifestyle. Toward intervening and controlling these environmental risk factors at an early Alzheimer's disease stage, understanding the role of microglia in Alzheimer's disease development, and targeting strategies to target microglia, could be essential to future Alzheimer's disease treatments.

Exploring the Significance of Microglial Phenotypes and Morphological Diversity in Neuroinflammation and Neurodegenerative Diseases: From Mechanisms to Potential Therapeutic Targets

Studying various microglial phenotypes and their functions in neurodegenerative diseases is crucial due to the intricate nature of their phenomics and their vital immunological role. Microglia undergo substantial phenomic changes, encompassing morphological, transcriptional, and functional aspects, resulting in distinct cell types with diverse structures, functions, properties, and implications. The traditional classification of microglia as ramified, M1 (proinflammatory), or M2 (anti-inflammatory) phenotypes is overly simplistic, failing to capture the wide range of recently identified microglial phenotypes in various brain regions affected by neurodegenerative diseases. Altered and activated microglial phenotypes deviating from the typical ramified structure are significant features of many neurodegenerative conditions. Understanding the precise role of each microglial phenotype is intricate and sometimes contradictory. This review specifically focuses on elucidating recent modifications in microglial phenotypes within neurodegenerative diseases. Recognizing the heterogeneity of microglial phenotypes in diseased states can unveil novel therapeutic strategies for targeting microglia in neurodegenerative diseases. Moreover, the exploration of the use of healthy isolated microglia to mitigate disease progression has provided an innovative perspective. In conclusion, this review discusses the dynamic landscape of mysterious microglial phenotypes, emphasizing the need for a nuanced understanding to pave the way for innovative therapeutic strategies for neurodegenerative diseases.

Mechanism of Salvia miltiorrhiza Bunge extract to alleviate Chronic Sleep Deprivation-Induced cognitive dysfunction in rats

BACKGROUND

Bidirectional communication between the gut microbiota and the brain may play an essential role in the cognitive dysfunction associated with chronic sleep deprivation(CSD). Salvia miltiorrhiza Bunge (Danshen, DS), a famous Chinese medicine and functional tea, is extensively used to protect learning and memory capacities, although the mechanism of action remains unknown.

PURPOSE

The purpose of this research was to explore the efficacy and the underlying mechanism of DS in cognitive dysfunction caused by CSD.

METHODS

DS chemical composition was analyzed by UPLC-QTOF-MS/MS. Forty rats were randomly assigned to five groups (n = 8): control (CON), model (MOD), low- (1.35 g/kg, DSL), high-dose (2.70 g/kg, DSH) DS group, and Melatonin(100 mg/kg, MT) group. A CSD rat model was established over 21 days. DS's effects and the underlying mechanism were explored using the open-field test(OFT), Morris water-maze(MWM), tissue staining(Hematoxylin and Eosin Staining, Nissl staining, Alcian blue-periodic acid SCHIFF staining, and Immunofluorescence), enzyme-linked immunosorbent assay, Western blot, quantitative real-time polymerase chain reaction(qPCR), and 16S rRNA sequencing.

RESULTS

We demonstrated that CSD caused gut dysbiosis and cognitive dysfunction. Furthermore, 16S rRNA sequencing demonstrated that Firmicutes and Proteobacteria were more in fecal samples from model group rats, whereas Bacteroidota and Spirochaetota were less. DS therapy, on the contrary hand, greatly restored the gut microbial community, consequently alleviating cognitive impairment in rats. Further research revealed that DS administration reduced systemic inflammation via lowering intestinal inflammation and barrier disruption. Following that, DS therapy reduced Blood Brain Barrier(BBB) and neuronal damage, further decreasing neuroinflammation in the hippocampus(HP). Mechanistic studies revealed that DS therapy lowered lipopolysaccharide (LPS) levels in the HP, serum, and colon, consequently blocking the TLR4/MyD88/NF-κB signaling pathway and its downstream pro-inflammatory products(IL-1β, IL-6, TNF-α, iNOS, and COX2) in the HP and colon.

CONCLUSION

DS treatment dramatically improved spatial learning and memory impairments in rats with CSD by regulating the composition of the intestinal flora, preserving gut and brain barrier function, and reducing inflammation mediated by the LPS-TLR4 signaling pathway. Our findings provide novel insight into the mechanisms by which DS treats cognitive dysfunction caused by CSD.

Brain metabolites are associated with sleep architecture and cognitive functioning in older adults

Sleep deficits are a possible risk factor for development of cognitive decline and dementia in older age. Research suggests that neuroinflammation may be a link between the two. This observational, cross-sectional study evaluated relationships between sleep architecture, neuroinflammation and cognitive functioning in healthy older adults. Twenty-two adults aged ≥60 years underwent whole-brain magnetic resonance spectroscopic imaging (in vivo method of visualizing increased brain temperatures as a proxy for neuroinflammation), supervised laboratory-based polysomnography, and comprehensive neurocognitive testing. Multiple regressions were used to assess relationships between magnetic resonance spectroscopic imaging-derived brain temperature and metabolites related to inflammation (choline; myo-inositol; N-acetylaspartate), sleep efficiency, time and % N3 sleep and cognitive performance. Choline, myo-inositol and N-acetylaspartate were associated with sleep efficiency and cognitive performance. Higher choline and myo-inositol in the bilateral frontal lobes were associated with slower processing speed and lower sleep efficiency. Higher choline and myo-inositol in bilateral frontoparietal regions were associated with better cognitive performance. Higher N-acetylaspartate around the temporoparietal junction and adjacent white matter was associated with better visuospatial function. Brain temperature was not related to cognitive or sleep outcomes. Our findings are consistent with the limited literature regarding neuroinflammation and its relationships with sleep and cognition in older age, which has implicated ageing microglia and astrocytes in circadian dysregulation, impaired glymphatic clearance and increased blood-brain barrier integrity, with downstream effects of neurodegeneration and cognitive decline. Inflammatory processes remain difficult to measure in the clinical setting, but magnetic resonance spectroscopic imaging may serve as a marker of the relationship between neuroinflammation, sleep and cognitive decline in older adults.

Neopterin mediates sleep deprivation-induced microglial activation resulting in neuronal damage by affecting YY1/HDAC1/TOP1/IL-6 signaling

INTRODUCTION

Sleep deprivation (SD) is a common disorder in modern society. Hippocampus is an important region of the brain for learning, memory, and emotions. Dysfunction of hippocampus can lead to severe learning and memory disorder, significantly affecting quality of life. SD is accompanied by hippocampal microglia activation and a surge in inflammatory factors, but the precise mechanism remains unclear. Moreover, the ongoing unknown persists regarding how activated microglia in SD lead to neuronal damage. Topoisomerase 1 (TOP1) plays an essential role in the inflammatory process, including the tumor system and viral infection. In this study, we observed a significant elevation in TOP1 levels in the hippocampus of mice subjected to SD. Therefore, we hypothesize that TOP1 may be implicated in SD-induced microglia activation and neuronal damage.

OBJECTIVES

To investigate the role of TOP1 in SD-induced microglial activation, neuronal damage, and neurobehavioral impairments, and the molecular basis of SD-induced elevated TOP1 levels.

METHODS

TOP1-specific knockout mice in microglia were used to study the effects of TOP1 on microglial activation and neuronal damage. Transcription factor prediction, RNA interference, ChIP-qPCR, ChIP-seq database analysis, and luciferase reporter assays were performed to explore the molecular mechanisms of YY1 transcriptional activation. Untargeted metabolic profiling was employed to investigate the material basis of YY1 transcriptional activation.

RESULTS

Knockdown of TOP1 in hippocampal microglia ameliorates SD-induced microglial activation, inflammatory response, and neuronal damage. Mechanistically, TOP1 mediates the release of IL-6 from microglia, which consequently leads to neuronal dysfunction. Moreover, elevated TOP1 due to SD were associated with neopterin, which was attributed to its promotion of elevated levels of H3K27ac in the TOP1 promoter region by disrupting the binding of YY1 and HDAC1.

CONCLUSION

The present study reveals that TOP1-mediated microglial activation is critical for SD induced hippocampal neuronal damage and behavioral impairments.

Sleep Deprivation Triggers Mitochondrial DNA Release in Microglia to Induce Neural Inflammation: Preventative Effect of Hydroxytyrosol Butyrate

Sleep deprivation (SD) triggers mitochondrial dysfunction and neural inflammation, leading to cognitive impairment and mental issues. However, the mechanism involving mitochondrial dysfunction and neural inflammation still remains unclear. Here, we report that SD rats exhibited multiple behavioral disorders, brain oxidative stress, and robust brain mitochondrial DNA (mtDNA) oxidation. In particular, SD activated microglia and microglial mtDNA efflux to the cytosol and provoked brain pro-inflammatory cytokines. We observed that the mtDNA efflux and pro-inflammatory cytokines significantly reduced with the suppression of the mtDNA oxidation. With the treatment of a novel mitochondrial nutrient, hydroxytyrosol butyrate (HTHB), the SD-induced behavioral disorders were significantly ameliorated while mtDNA oxidation, mtDNA release, and NF-κB activation were remarkably alleviated in both the rat brain and the N9 microglial cell line. Together, these results indicate that microglial mtDNA oxidation and the resultant release induced by SD mediate neural inflammation and HTHB prevents mtDNA oxidation and efflux, providing a potential treatment for SD-induced mental issues.

Propofol improves sleep deprivation-induced sleep structural and cognitive deficits via upregulating the BMAL1 expression and suppressing microglial M1 polarization

BACKGROUND

Sleep deprivation (SD) is a growing global health problem with many deleterious effects, such as cognitive impairment. Microglia activation-induced neuroinflammation may be an essential factor in this. Propofol has been shown to clear sleep debt after SD in rats. This study aims to evaluate the effects of propofol-induced sleep on ameliorating sleep quality impairment and cognitive decline after 48 h SD.

METHODS

Almost 8-12-week-old rats were placed in the SD system for 48 h of natural sleep or continuous SD. Afterwards, rats received propofol (20 mg·kg-1·h-1, 6 h) via the tail or slept naturally. The Morris water maze (MWM) and Y-maze test assessed spatial learning and memory abilities. Rat EEG/EMG monitored sleep. The expression of brain and muscle Arnt-like protein 1 (BMAL1), brain-derived neurotrophic factor (BDNF) in the hippocampus and BMAL1 in the hypothalamus were assessed by western blot. Enzyme-linked immunosorbent assay detected IL-6, IL-1β, arginase 1 (Arg1), and IL-10 levels in the hippocampus. Immunofluorescence was used to determine microglia expression as well as morphological changes.

RESULTS

Compared to the control group, the sleep-deprived rats showed poor cognitive performance on both the MWM test and the Y-maze test, accompanied by disturbances in sleep structure, including increased total sleep time, and increased time spent and delta power in non-rapid eye movement sleep. In addition, SD induces abnormal expression of the circadian rhythm protein BMAL1, activates microglia, and causes neuroinflammation and nerve damage. Propofol reversed these changes and saved sleep and cognitive impairment. Furthermore, propofol treatment significantly reduced hippocampal IL-1β and IL-6 levels, increased BDNF, Arg1, and IL-10 levels, and switched microglia surface markers from the inflammatory M1 type to the anti-inflammatory M2 type.

CONCLUSION

Propofol reduces SD-induced cognitive impairment and circadian rhythm disruption, possibly by lowering neuronal inflammation and switching the microglia phenotype from an M1 to an M2 activated state, thus exerting neuroprotective effects.

Sleep rebound leads to marked recovery of prolonged sleep deprivation-induced adversities in the stress response and hippocampal neuroplasticity of male rats

BACKGROUND

Sleep disturbances are not only frequent symptoms, but also risk factors for major depressive disorder. We previously reported that depressed patients who experienced "Hypersomnia" showed a higher and more rapid response rate under paroxetine treatment, but the underlying mechanism remains unclear. The present study was conducted to clarify the beneficial effects of sleep rebound through an experimental "Hypersomnia" rat model on glucocorticoid and hippocampal neuroplasticity associated with antidepressive potency.

METHODS

Thirty-four male Sprague-Dawley rats were subjected to sham treatment, 72-h sleep deprivation, or sleep deprivation and subsequent follow-up for one week. Approximately half of the animals were sacrificed to evaluate adrenal weight, plasma corticosterone level, hippocampal content of mRNA isoforms, and protein of the brain-derived neurotrophic factor (Bdnf) gene. In the other half of the rats, Ki-67- and doublecortin (DCX)-positive cells in the hippocampus were counted via immunostaining to quantify adult neurogenesis.

RESULTS

Prolonged sleep deprivation led to adrenal hypertrophy and an increase in the plasma corticosterone level, which had returned to normal after one week follow-up. Of note, sleep deprivation-induced decreases in hippocampal Bdnf transcripts containing exons II, IV, VI, and IX and BDNF protein levels, Ki-67-(+)-proliferating cells, and DCX-(+)-newly-born neurons were not merely reversed, but overshot their normal levels with sleep rebound.

LIMITATIONS

The present study did not record electroencephalogram or assess behavioral changes of the sleep-deprived rats.

CONCLUSIONS

The present study demonstrated that prolonged sleep deprivation-induced adversities are reversed or recovered by sleep rebound, which supports "Hypersomnia" in depressed patients as having a beneficial pharmacological effect.

Efficacy of melatonin in alleviating disorders arising from repeated exposure to sevoflurane in males and females of the Wistar rats during preadolescence

Pediatricians use sevoflurane due to its fast action and short recovery time. However, studies have shown that repeated exposure to anesthesia can affect learning and memory. Melatonin, an indole-type neuroendocrine hormone, has significant anti-inflammatory, and neuroprotective properties. Melatonin's impact on cognitive behavior in sevoflurane-anesthetized males and females of the Wistar rats during preadolescence was examined in this research. The cognitive function was evaluated by shuttle box and morris water maze tests, while interleukin-10, Catalase (CAT), Malondialdehyde (MDA), and Tumor Necrosis Factor-α (TNF-α) were evaluated using ELISA kits. The expression levels of the apoptosis-linked proteins, Bax, Bcl-2, and caspase-3, were determined using the western blotting technique. The learning and memory latencies of the rats were more significant in the sevoflurane groups than in the control group; however, the latencies were significantly shorter in the sevoflurane and melatonin groups than in the control group. The levels of MDA, TNF-α, Bax, and caspase-3 were significantly higher in the sevoflurane groups than in the control group. We also found that the levels of CAT and Bcl-2 were significantly reduced in the sevoflurane groups compared to the control group. Increasing levels of CAT, Bcl-2, and decreasing levels of MDA, TNF-α, Bax, and caspase-3 in response to melatonin indicate a possible contribution to the recovery from the sevoflurane impairment. Melatonin shows neuroprotective effects in male and female rats with sevoflurane-induced cognitive impairment. This suggests melatonin could be a valuable treatment for learning and memory deficits resulting from repeated exposure to sevoflurane, possibly by controlling apoptosis, oxidative stress, and inflammation.

Exploring the potential relationship between short sleep risks and cognitive function from the perspective of inflammatory biomarkers and cellular pathways: Insights from population-based and mice studies

AIMS

The molecular mechanism of short-sleep conditions on cognition remains largely unknown. This research aimed to investigate associations between short sleep, inflammatory biomarkers and cognitive function in the US population (NHANES data 2011-2014) and explore cellular mechanisms in mice.

METHODS

Systemic immune-inflammation index (SII) was calculated using blood-cell based biomarkers. Further, we employed integrated bioinformatics and single-cell transcriptomics (GSE137665) to examine how short sleep exposure influenced the molecular pathways associated with inflammation in the brain. To explore the signaling pathways and biological processes of sleep deprivation, we carried out enrichment analyses utilizing the GO and KEGG databases.

RESULTS

Population results showed that, compared with normal sleep group, severe short sleep was associated with lower cognitive ability in all the four tests. Moreover, a higher SII level was correlated with lower scores of cognitive tests. In mice study, elevated activation of the inflammatory pathway was observed in cell subgroups of neurons within the sleep deprivation and recovery sleep cohorts. Additionally, heightened expression of oxidative stress and integrated stress response pathways was noted in GABAergic neurons during sleep deprivation.

CONCLUSION

This study contributed to the understanding of the influence of short sleep on cognitive function and its cellular mechanisms.

Microglia modulate sleep/wakefulness under baseline conditions and under acute social defeat stress in adult mice

Although sleep is tightly regulated by multiple neuronal circuits in the brain, nonneuronal cells such as glial cells have been increasingly recognized as crucial sleep regulators. Recent studies have shown that microglia may act to maintain wakefulness. Here, we investigated the possible involvement of microglia in the regulation of sleep quantity and quality under baseline and stress conditions through electroencephalography (EEG)/electromyography (EMG) recordings, and by employing pharmacological methods to eliminate microglial cells in the adult mouse brain. We found that severe microglial depletion induced by the colony-stimulating factor 1 receptor (CSF1R) antagonist PLX5622 (PLX) reversibly decreased the total wake time and the wake episode duration and increased the EEG slow-wave power during wakefulness under baseline conditions. To examine the role of microglia in sleep/wake regulation under mental stress, we used the acute social defeat stress (ASDS) paradigm, an ethological model for psychosocial stress. Sleep analysis under ASDS revealed that microglial depletion exacerbated the stress-induced decrease in the total wake time and increase in anxiety-like behaviors in the open field test. These results demonstrate that microglia actively modulate sleep quantity and architecture under both baseline and stress conditions. Our findings suggest that microglia may potentially provide resilience against acute psychosocial stress by regulating restorative sleep.

Unlocking the Therapeutic Potential of Exosomes Derived From Nasal Olfactory Mucosal Mesenchymal Stem Cells: Restoring Synaptic Plasticity, Neurogenesis, and Neuroinflammation in Schizophrenia

BACKGROUND AND HYPOTHESIS

Schizophrenia (SCZ) is a multifaceted mental disorder marked by a spectrum of symptoms, including hallucinations, delusions, cognitive deficits, and negative symptoms. Its etiology involves intricate interactions between genetic and environmental factors, posing significant challenges for effective treatment. We hypothesized that intranasal administration of exosomes derived from nasal olfactory mucosal mesenchymal stem cells (OM-MSCs-exos) could alleviate SCZ-like behaviors in a murine model induced by methylazoxymethanol (MAM).

STUDY DESIGN

We conducted a comprehensive investigation to assess the impact of intranasally delivered OM-MSC-exos on SCZ-like behaviors in MAM-induced mice. This study encompassed behavioral assessments, neuroinflammatory markers, glial activation, synaptic protein expression, and neurogenesis within the hippocampus.

STUDY RESULTS

Our findings demonstrated that intranasal administration of OM-MSC-exos effectively ameliorated SCZ-like behaviors, specifically addressing social withdrawal and sensory gating deficits in the MAM-induced murine model. Furthermore, OM-MSC-exos intervention yielded a reduction in neuroinflammatory markers and a suppression of microglial activation within the hippocampus. Simultaneously, we observed an upregulation of key synaptic protein expression, including PSD95 and TH, the rate-limiting enzyme for dopamine biosynthesis.

CONCLUSIONS

Our study underscores the therapeutic potential of OM-MSC-exos in mitigating SCZ-like behavior. The OM-MSC-exos have the capacity to modulate glial cell activation, diminish neuroinflammation, and promote BDNF-associated synaptic plasticity and neurogenesis, thus ameliorating SCZ-like behaviors. In summary, intranasal administration of OM-MSC-exos offers a multifaceted approach to address SCZ mechanisms, promising innovative treatments for this intricate disorder.

Long-term enhancements in antidepressant efficacy and neurogenesis: Effects of intranasal co-administration of neuropeptide Y 1 receptor (NPY1R) and galanin receptor 2 (GALR2) agonists in the ventral hippocampus

This study evaluates the sustained antidepressant-like effects and neurogenic potential of a 3-day intranasal co-administration regimen of galanin receptor 2 (GALR2) agonist M1145 and neuropeptide Y Y1 receptor (NPY1R) agonist [Leu31, Pro34]NPY in the ventral hippocampus of adult rats, with outcomes analyzed 3 weeks post-treatment. Utilizing the forced swimming test (FST), we found that this co-administration significantly enhances antidepressant-like behaviors, an effect neutralized by the GALR2 antagonist M871, highlighting the synergistic potential of these neuropeptides in modulating mood-related behaviors. In situ proximity ligation assay (PLA) indicated a significant increase in GALR2/NPYY1R heteroreceptor complexes in the ventral hippocampal dentate gyrus, suggesting a molecular basis for the behavioral outcomes observed. Moreover, proliferating cell nuclear antigen (PCNA) immunolabeling revealed increased cell proliferation in the subgranular zone of the dentate gyrus, specifically in neuroblasts as evidenced by co-labeling with doublecortin (DCX), without affecting quiescent neural progenitors or astrocytes. The study also noted a significant uptick in the number of DCX-positive cells and alterations in dendritic morphology in the ventral hippocampus, indicative of enhanced neuronal differentiation and maturation. These morphological changes highlight the potential of these agonists to facilitate the functional integration of new neurons into existing neural circuits. By demonstrating the long-lasting effects of a brief, 3-day intranasal administration of GALR2 and NPY1R agonists, our findings contribute significantly to the understanding of neuropeptide-mediated neuroplasticity and herald novel therapeutic strategies for the treatment of depression and related mood disorders, emphasizing the therapeutic promise of targeting neurogenesis and neuronal maturation processes.

LC-MS/MS analysis of Shenghui decoction component and its effect on learning and memory and neuroprotection in sleep deprivation model mice

BACKGROUND

In recent years, sleep problems have emerged as a significant factor in the development of diseases that influence cognitive function. The inflammatory response may have a role in the neurobiological processes of sleep deprivation, resulting in impairment of memory and learning. Shenghui Decoction (SHD) is a classic formula in Chinese medicine used to treat forgetfulness and insomnia. However, it remains unclear whether the anti-inflammatory effects of SHD are specifically linked to the inhibition of P2X7R and p38MAPK.

METHODS

Analysis of chemical constituents of Shenghui Decoction based on UPLC-Q-TOF-MS / MS. The learning and memory competency of the mice was assessed using the new object recognition and Morris water maze tests. The morphology of hippocampus neurons was observed using HE staining, and the expression of inflammatory factors was measured using ELISA and immunofluorescence. The expression of P2X7R and p38MAPK in the hippocampus was analyzed via real-time PCR and Western blotting. Additionally, the components absorbed into the bloodstream of SHD were analyzed.

RESULTS

The study found that SHD contains 47 chemical constituents, including phenolic acids, flavonoids, iridoids, and triterpenoids. In addition, it was observed that SHD significantly improved the learning and memory abilities of the mice. SHD also improved the morphology of hippocampus neurons. The expression of inflammatory factors was decreased in the SHD-treated mice. Additionally, the expression of P2X7R and p38MAPK was decreased in the hippocampus of the SHD-treated mice. Fifteen prototype chemical constituents were detected in blood.

CONCLUSIONS

The study suggests that SHD could be a viable treatment for cognitive impairments associated with brain inflammation. The therapeutic effects of SHD are likely due to its chemical components, including phenolic acids, flavonoids, iridoids, and triterpenoids. SHD can improve learning and memory impairment caused by sleep deprivation through the P2X7R/p38MAPK inflammatory signaling pathways.

Resveratrol prevents cognitive deficits induced by sleep deprivation via modulating sirtuin 1 associated pathways in the hippocampus

Accumulating evidence confirms that sleep insufficiency is a high risk factor for cognitive impairment, which involves inflammation and synaptic dysfunction. Resveratrol, an agonist of the Sirt1, has demonstrated anti-inflammation and neuroprotective effects in models of Alzheimer's disease, Parkinson's disease, and schizophrenia. However, the beneficial effects of resveratrol on sleep deprivation-induced cognitive deficits and its underlying molecular mechanisms are unclear. In the present study, thirty-two male C57BL/6 J mice were randomly divided into a Control+DMSO group, Control+Resveratrol group, SD+DMSO group, and SD+Resveratrol group. The mice in the SD+Resveratrol group underwent 5 days of sleep deprivation after pretreatment with resveratrol (50 mg/kg) for 2 weeks, while the mice in the SD+DMSO group only underwent sleep deprivation. After sleep deprivation, we evaluated spatial learning and memory function using the Morris water maze test. We used general molecular biology techniques to detect changes in levels of pro-inflammatory cytokines and Sirt1/miR-134 pathway-related synaptic plasticity proteins. We found that resveratrol significantly reversed sleep deprivation-induced learning and memory impairment, elevated interleukin-1β, interleukin-6, and tumor necrosis factor-α levels, and decreased brain-derived neurotrophic factor, tyrosine kinase receptor B, postsynaptic density protein-95, and synaptophysin levels by activating the Sirt1/miR-134 pathway. In conclusion, resveratrol is a promising agent for preventing sleep deprivation-induced cognitive dysfunction by reducing pro-inflammatory cytokines and improving synaptic function via the Sirt1/miR-134 pathway.

Enhancement of neurogenesis and cognition through intranasal co-delivery of galanin receptor 2 (GALR2) and neuropeptide Y receptor 1 (NPY1R) agonists: a potential pharmacological strategy for cognitive dysfunctions

BACKGROUND

Spatial memory deficits and reduced neuronal survival contribute to cognitive decline seen in the aging process. Current treatments are limited, emphasizing the need for innovative therapeutic strategies. This research explored the combined effects of intranasally co-administered galanin receptor 2 (GALR2) and neuropeptide Y1 receptor (NPY1R) agonists, recognized for their neural benefits, on spatial memory, neuronal survival, and differentiation in adult rats. After intranasal co-delivery of the GALR2 agonist M1145 and a NPY1R agonist to adult rats, spatial memory was tested with the object-in-place task 3 weeks later. We examined neuronal survival and differentiation by assessing BrdU-IR profiles and doublecortin (DCX) labeled cells, respectively. We also used the GALR2 antagonist M871 to confirm GALR2's crucial role in promoting cell growth.

RESULTS

Co-administration improved spatial memory and increased the survival rate of mature neurons. The positive effect of GALR2 in cell proliferation was confirmed by the nullifying effects of its antagonist. The treatment boosted DCX-labeled newborn neurons and altered dendritic morphology, increasing cells with mature dendrites.

CONCLUSIONS

Our results show that intranasal co-delivery of GALR2 and NPY1R agonists improves spatial memory, boosts neuronal survival, and influences neuronal differentiation in adult rats. The significant role of GALR2 is emphasized, suggesting new potential therapeutic strategies for cognitive decline.

Differential effects of sleep deprivation on behavior and microglia in a brain-region-specific manner in young and aged male mice

Microglia, resident immune cells in the central nervous system, constantly monitor the state of the surrounding brain activity. The animal model induced by sleep deprivation (SD) is widely used to study the pathophysiological mechanisms of insomnia and bipolar disorder. However, it remains unclear whether SD affects behaviors in young and aged male mice and microglia in various brain regions. In this study, we confirmed brain region-specific changes in microglial density and morphology in the accumbens nucleus (Acb), amygdala (AMY), cerebellum (Cb), corpus callosum (cc), caudate putamen, hippocampus (HIP), hypothalamus (HYP), medial prefrontal cortex (mPFC), and thalamus (TH) of young mice. In addition, the density of microglia in old mice was higher than that in young mice. Compared with young mice, old mice showed a markedly increased microglial size, decreased total length of microglial processes, and decreased maximum length. Importantly, we found that 48-h SD decreased microglial density and morphology in old mice, whereas SD increased microglial density and morphology in most observed brain regions in young mice. SD-induced hyperactivity was observed only in young mice but not in old mice. Moreover, microglial density (HIP, AMY, mPFC, CPu) was significantly positively correlated with behaviors in SD- and vehicle-treated young mice. Contrarily, negative correlations were shown between the microglial density (cc, Cb, TH, HYP, Acb, AMY) and behaviors in vehicle-treated young and old mice. These results suggest that SD dysregulates the homeostatic state of microglia in a region- and age-dependent manner. Microglia may be involved in regulating age-related behavioral responses to SD.

Effects of minocycline on dendrites, dendritic spines, and microglia in immature mouse brains after kainic acid-induced status epilepticus

PURPOSE

This study aimed to investigate whether minocycline could influence alterations of microglial subtypes, the morphology of dendrites and dendritic spines, the microstructures of synapses and synaptic proteins, or even cognition outcomes in immature male mice following status epilepticus (SE) induced by kainic acid.

METHODS

Golgi staining was performed to visualize the dendrites and dendritic spines of neurons of the hippocampus. The microstructures of synapses and synaptic proteins were observed using transmission electron microscopy and western blotting analysis, respectively. Microglial reactivation and their markers were evaluated using flow cytometry. The Morris water maze (MWM) test was used to analyze spatial learning and memory ability.

RESULTS

Significant partial spines increase (predominate in thin spines) was observed in the dendrites of neurons after acute SE and partial loss (mainly in thin spines) was presented by days 14 and 28 post-SE. The postsynaptic ultrastructure was impaired on the 7th and 14th days after SE. The proportion of M1 microglia increased significantly only after acute SE Similarly, the proportion of M2 microglia increased in the acute stage with high expression levels of all surface markers. In contrast, a decrease in M2 microglia and their markers was noted by day 14 post-SE. Minocycline could reverse the changes in dendrites and synaptic proteins caused by SE, and increase the levels of synaptic proteins. Meanwhile, minocycline could inhibit the reactivation of M1 microglia and the expression of their markers, except for promoting CD200R. In addition, treatment with minocycline could regulate the expression of M2 microglia and their surface markers, as well as ameliorating the impaired spatial learning and memory on the 28th day after SE.

CONCLUSIONS

Dendritic spines and microglia are dynamically changed after SE. Minocycline could ameliorate the impaired cognition in the kainic acid-induced mouse model by decreasing the damage to dendrites and altering microglial reactivation.

Microglia dysfunction drives disrupted hippocampal amplitude of low frequency after acute kidney injury

AIMS

Acute kidney injury (AKI) has been associated with a variety of neurological problems, while the neurobiological mechanism remains unclear. In the present study, we utilized resting-state functional magnetic resonance imaging (rs-fMRI) to detect brain injury at an early stage and investigated the impact of microglia on the neuropathological mechanism of AKI.

METHODS

Rs-fMRI data were collected from AKI rats and the control group with a 9.4-Tesla scanner at 24, 48, and 72 h post administration of contrast medium or saline. The amplitude of low-frequency fluctuations (ALFF) was then compared across the groups at each time course. Additionally, flow cytometry and SMART-seq2 were employed to evaluate microglia. Furthermore, pathological staining and Western blot were used to analyze the samples.

RESULTS

MRI results revealed that AKI led to a decreased ALFF in the hippocampus, particularly in the 48 h and 72 h groups. Additionally, western blot suggested that AKI-induced the neuronal apoptosis at 48 h and 72 h. Flow cytometry and confocal microscopy images demonstrated that AKI activated the aggregation of microglia into neurons at 24 h, with a strong upregulation of M1 polarization at 48 h and peaking at 72 h, accompanying with the release of proinflammatory cytokines. The ALFF value was strongly correlated with the proportion of microglia (|r| > 0.80, p < 0.001).

CONCLUSIONS

Our study demonstrated that microglia aggregation and inflammatory factor upregulation are significant mechanisms of AKI-induced neuronal apoptosis. We used fMRI to detect the alterations in hippocampal function, which may provide a noninvasive method for the early detection of brain injury after AKI.

SIRT6 Improves Hippocampal Neurogenesis Following Prolonged Sleep Deprivation Through Modulating Energy Metabolism in Developing rats

OBJECTIVE

Prolonged sleep deprivation is known to have detrimental effects on the hippocampus during development or in adulthood. Furthermore, it is well-established that sleep deprivation disrupts energy metabolism broadly. SIRT6 is a critical regulator of energy metabolism in both central and peripheral tissues. This study aims to investigate the role of SIRT6 in modulating hippocampal neurogenesis following sleep deprivation during development, and elucidate the underlying mechanism.

METHODS

Male Sprague-Dawley rats, aged three weeks, were subjected to 2 weeks of sleep deprivation using the modified multiple platform method. Metabolomic profiling was carried out using the liquid chromatography-electrospray ionization-tandem mass spectrometry (LC‒ESI‒MS/MS). To investigate the role of SIRT6 in energy metabolism, the rats were administered with either the SIRT6-specific inhibitor, OSS128167, or SIRT6-overexpressing adeno-associated virus (AAV). Hippocampal neurogenesis was assessed by immunostaining with markers for neural stem cells (SOX2), immature neurons [doublecortin (DCX)] and newborn cells (BrdU). Sparse labeling of adult neurons was used to determine the density of dendritic spines in the dentate gyrus (DG). The Y-maze and novel object recognition (NOR) tests were performed to evaluate the spatial and recognition memory. SIRT6 expression was examined using immunofluorescence and western blotting (WB). The inhibition of SIRT6 was confirmed by assessing the acetylation of histone 3 lysine 9 (aceH3K9), a well-known substrate of SIRT6, through WB.

RESULTS

Sleep deprivation for a period of two weeks leads to inhibited hippocampal neurogenesis, reduced density of dendritic spines in the DG, and impaired memory, accompanied by decreased SIRT6 expression and disrupted energy metabolism. Similar to sleep deprivation, administration of OSS128167 significantly decreased energy metabolism, leading to reduced neurogenesis and memory dysfunction. Notably, the abnormal hippocampal energy metabolism, neurogenetic pathological changes and memory dysfunction caused by sleep deprivation were alleviated by SIRT6 overexpression in the DG.

CONCLUSION

Our results suggest that SIRT6 plays a critical role in maintaining energy metabolism homeostasis in the hippocampus after sleep deprivation, promoting hippocampal neurogenesis and enhancing memory during development.

Altered in vivo early neurogenesis traits in patients with depression: Evidence from neuron-derived extracellular vesicles and electroconvulsive therapy

BACKGROUND

The neurogenesis hypothesis is a promising candidate etiologic hypothesis for depression, and it is associated with electroconvulsive therapy (ECT). However, human in vivo molecular-level evidence is lacking.

OBJECTIVE

We used neuron-derived extracellular vesicles (NDEVs) as a "window to the neurons" to explore the in vivo neurogenesis status associated with ECT in patients with treatment-resistant depression (TRD).

METHODS

In this study, we enrolled 40 patients with TRD and 35 healthy controls (HCs). We isolated NDEVs from the plasma of each participant to test the levels of doublecortin (DCX), a marker of neurogenesis, and cluster of differentiation (CD) 81, a marker of EVs. We also assessed the plasma levels of brain-derived neurotrophic factor (BDNF), a protein that is known to be associated with ECT and neuroplastic processes.

RESULTS

Our findings indicated that both the levels of DCX in NDEVs and BDNF in plasma were significantly lower in TRD patients compared to HCs at baseline, but increased following ECTs. Conversely, levels of CD81 in NDEVs were found higher in TRD patients at baseline, but did not change after the ECT treatments. Exploratory analyses revealed that lower levels of BDNF in plasma and DCX in NDEVs, along with higher CD81 levels in NDEVs, were associated with more severe depressive symptoms and reduced cognitive function at baseline. Furthermore, higher baseline CD81 concentrations in NDEVs were correlated with greater decreases in depression symptoms.

CONCLUSIONS

We first present human in vivo evidence of early neurogenesis using DCX through NDEVs: decreased in TRD patients, increased after ECTs.

Microglia and Sleep Disorders

Sleep is a physiological state that is essential for maintaining physical and mental health. Sleep disorders and sleep deprivation therefore have many adverse effects, including an increased risk of metabolic diseases and a decline in cognitive function that may be implicated in the long-term development of neurodegenerative diseases. There is increasing evidence that microglia, the resident immune cells of the central nervous system (CNS), are involved in regulating the sleep-wake cycle and the CNS response to sleep alteration and deprivation. In this chapter, we will discuss the involvement of microglia in various sleep disorders, including sleep-disordered breathing, insomnia, narcolepsy, myalgic encephalomyelitis/chronic fatigue syndrome, and idiopathic rapid-eye-movement sleep behavior disorder. We will also explore the impact of acute and chronic sleep deprivation on microglial functions. Moreover, we will look into the potential involvement of microglia in sleep disorders as a comorbidity to Alzheimer's disease and Parkinson's disease.

The Role of Silymarin in Mitigating Inflammation and Cognitive Impairment Induced by Ovariectomy in Wistar Rats

Background. Silymarin, a polyphenolic flavonoid found in milk thistle, has been used to treat liver and brain injuries in humans and animals. The study aims to investigate the protective effects of silymarin on spatial and passive avoidance memory, oxidative stress, and inflammatory factors in the brain and liver tissues of ovariectomized (OVX) Wistar rats. Methods. The study involved 30 female Wistar rats divided into control, sham, and three silymarin-treated groups. After ovariectomy, rats underwent CT scan, and some of them were administered silymarin via gavage for 2 months. Memory and learning were assessed using Morris water maze and shuttle box tests. Brain and liver tissues were analyzed for inflammatory factors (IL-1β, TNFα, and IL-6) and oxidative stress markers (CAT, SOD, and MDA) after sacrifice. Results. Silymarin improved spatial memory and fear learning compared to the sham group ($P\le 0.05$ to $P\le 0.001$). It also significantly reduced IL-1β, TNF-α, and IL-6 levels in the cortex, hippocampus, and liver ($P\le 0.05$ to $P\le 0.0001$) and increased CAT and SOD while decreasing MDA levels ($P\le 0.05$ to $P\le 0.001$) compared to control and sham groups. Conclusion. Long-term administration of silymarin extract can improve learning and memory, reverse cognitive impairment caused by ovariectomy, and reduce oxidative stress and inflammatory factors induced by ovariectomy in the liver and brain of Wistar rats. This is due to the reduction in MDA levels and an increase in CAT activity, although silymarin has some effect on SOD at high doses.

Impact of Preoperative Sleep Disturbances on Postoperative Delirium in Patients with Intracranial Tumors: A Prospective, Observational, Cohort Study

Background

Postoperative delirium (POD) is prevalent in craniotomy patients and is associated with high mortality. Sleep disturbances are receiving increasing attention from clinicians as associated risk factors for postoperative complications. This study aimed to determine the impact of preoperative sleep disturbances on POD in craniotomy patients.

Methods

We recruited 130 patients undergoing elective craniotomy for intracranial tumors between May 1st and December 30th, 2022. Preoperative subjective sleep disturbances were assessed using the Pittsburgh Sleep Quality Index on the day of admission. We also measured objective perioperative sleep patterns using a dedicated sleep monitoring device 3 days before and 3 days after the surgery. POD was assessed twice daily using the Confusion Assessment Model for the Intensive Care Unit within the first week after craniotomy.

Results

Preoperative sleep disturbances were diagnosed in 49% of the study patients, and POD was diagnosed in 22% of all the study patients. Sleep disturbances were an independent risk factor for POD (OR: 2.709, 95% CI: 1.020-7.192, P = 0.045). Other risk factors for POD were age (OR: 3.038, 95% CI: 1.195-7.719, P = 0.020) and the duration of urinary catheterization (OR: 1.246, 95% CI: 1.025-1.513, P = 0.027). Perioperative sleep patterns (including sleep latency, deep sleep duration, frequency of awakenings, apnea-hypopnea index, and sleep efficiency) were significantly associated with POD.

Conclusion

This study demonstrated that preoperative sleep disturbances predispose patients undergoing craniotomy to POD, also inferred a correlation between perioperative sleep patterns and POD. The targeted screening and intervention specifically for sleep disturbances during the perioperative period are immensely required.

Therapeutic Potential of Kaempferol against Sleep Deprivation-Induced Cognitive Impairment: Modulation of Neuroinflammation and Synaptic Plasticity Disruption in Mice

Sleep deprivation (SD) has led to a rise in cognitive impairment (CI) cases. Kaempferol (KMP), known for its anti-inflammatory and antiapoptotic properties, holds promise in countering SD-induced CI. Experimental validation using a sleep-deprived CI model confirmed KMP's efficacy in mitigating CI. Immunofluorescence investigations emphasized diminished activation of astrocytes and reduced the proliferation of microglia in the hippocampus of mice subjected to SD. Subsequently, network pharmacological analyses were conducted and found that KMP may be closely related to the mitogen-activated protein kinase (MAPK) pathway in SD-induced CI. The influence of KMP on the MAPK pathway was verified by the observed decrease in the expression of phosphorylated JNK (p-JNK) and p38 (p-p38). Analyzing hippocampal AMPARS and NMDARS expression indicated KMP's ability to enhance GluA1 phosphorylation (Ser831 and Ser845) and GluN2A levels. Patch clamp assays demonstrated heightened excitatory transmitter transmission in the hippocampus, suggesting KMP's positive influence. Overall, KMP combats neuroinflammation via MAPK inhibition, augments synaptic function, and addresses learning and memory dysfunction in sleep-deprived mice.

Phoenixin-20 ameliorates Sevoflurane inhalation-induced post-operative cognitive dysfunction in rats via activation of the PKA/CREB signaling

Post-operative cognitive dysfunction (POCD) is a common complication after surgery due to the usage of anesthetics, such as Sevoflurane, which severely impacts the life quality of patients. Currently, the pathogenesis of Sevoflurane-induced POCD has not been fully elucidated but is reportedly involved with oxidative stress (OS) injury and aggravated inflammation. Phoenixin-20 (PNX-20) is a PNX peptide consisting of 20 amino acids with promising inhibitory effects on OS and inflammation. Herein, we proposed to explore the potential protective function of PNX-20 on Sevoflurane inhalation-induced POCD in rats. Sprague-Dawley (SD) rats were treated with 100 ng/g PNX-20 for 7 days with or without pre-inhalation with 2.2% Sevoflurane. Markedly increased escape latency and decreased time in the target quadrant in the Morris water maze (MWM) test, and aggravated pathological changes and apoptosis in the hippocampus tissue were observed in Sevoflurane-treated rats, which were markedly attenuated by PNX-20. Furthermore, the aggravated inflammation and OS in the hippocampus observed in Sevoflurane-treated rats were notably abolished by PNX-20. Moreover, the brain-derived neurotrophic factor (BDNF), protein kinase A (PKA), and phospho-cAMP response element binding protein/cAMP response element binding protein (p-CREB/CREB) levels were markedly decreased in Sevoflurane-treated rats, which were memorably increased by PNX-20. Our results indicated that PNX-20 ameliorated Sevoflurane inhalation-induced POCD in rats via the activation of PKA/CREB signaling, which might supply a new treatment approach for POCD.

Akkermansia muciniphila supplementation prevents cognitive impairment in sleep-deprived mice by modulating microglial engulfment of synapses

The microbiome-gut-brain axis plays a crucial role in many neurological diseases, including mild cognitive impairment. Sleep deprivation (SD) induces cognitive decline accompanied by alterations in the gut microbiota. However, the role of gut microbiota alterations in SD-induced cognitive dysfunction and the underlying mechanisms remain unclear. Here, we found that dysbiosis of the gut microbiota following pretreatment with broad-spectrum antibiotics worsens SD-induced cognitive impairment in mice. Fecal microbiota transplantation from SD mice to healthy mice induced cognitive impairment. Additionally, the abundance of Akkermansia muciniphila (A. muciniphila) in the mouse gut microbiota was significantly reduced after 7 days of SD. A. muciniphila pretreatment alleviated cognitive dysfunction and prevented synaptic reduction in the hippocampus in SD mice. A. muciniphila pretreatment inhibited extensive microglial activation and synaptic engulfment in the hippocampus of SD mice. Metabolomics analysis revealed that A. muciniphila pretreatment increased the serum acetate and butanoic acid levels in SD mice. Finally, pretreatment with short-chain fatty acids (SCFAs) inhibited microglial synaptic engulfment and prevented neuronal synaptic loss in SD mice and primary microglia-neuron co-culture following LPS stimulation. Together, our findings illustrate that gut dysbiosis plays an essential role in SD-induced cognitive impairment by activating microglial engulfment at synapses. A. muciniphila supplementation may be a novel preventative strategy for SD-induced cognitive dysfunction, by increasing SCFAs production and maintaining microglial homeostasis.

Neuroinflammation, memory, and depression: new approaches to hippocampal neurogenesis

As one of most common and severe mental disorders, major depressive disorder (MDD) significantly increases the risks of premature death and other medical conditions for patients. Neuroinflammation is the abnormal immune response in the brain, and its correlation with MDD is receiving increasing attention. Neuroinflammation has been reported to be involved in MDD through distinct neurobiological mechanisms, among which the dysregulation of neurogenesis in the dentate gyrus (DG) of the hippocampus (HPC) is receiving increasing attention. The DG of the hippocampus is one of two niches for neurogenesis in the adult mammalian brain, and neurotrophic factors are fundamental regulators of this neurogenesis process. The reported cell types involved in mediating neuroinflammation include microglia, astrocytes, oligodendrocytes, meningeal leukocytes, and peripheral immune cells which selectively penetrate the blood-brain barrier and infiltrate into inflammatory regions. This review summarizes the functions of the hippocampus affected by neuroinflammation during MDD progression and the corresponding influences on the memory of MDD patients and model animals.

Interplay between stress, sleep, and BDNF in a high-risk sample of young adults

Children in institutional care have a high risk to experience childhood adversities (CAs), with consequences for physical and mental well-being. The long-term effects of CAs on the brain, including consequences for neuronal plasticity and sleep, are poorly understood. This study examined the interplay between stress (including CAs), sleep, and brain-derived neurotrophic factor (BDNF), a prominent marker for neuronal plasticity. Participants (N = 131, mean age = 26.3±3.4 years, 40 females) with residential youth-care history completed questionnaires measuring CAs (Childhood Trauma Questionnaire, CTQ), psychological well-being (World Health Organization-Five Well-Being Index, WHO-5), and sleep disturbances (Pittsburgh Sleep Quality Inventory, PSQI). Hair cortisol and serum BDNF concentration were measured using enzyme-linked immunosorbent assays. The analyses were conducted by using bootstrap regression models. There was no association of stress parameters or sleep with BDNF concentration. However, we found a significant association of CAs and well-being with sleep disturbances. Last, we found an association between CAs and BDNF in sleep-healthy but not sleep-disturbed participants. Our findings indicated a role of sleep disturbance in the association between stress and BDNF. Still, further studies are warranted using vulnerable groups at-risk to understand long-term effects on mental health and sleep.

Qi Fu Yin ameliorates neuroinflammation through inhibiting RAGE and TLR4/NF-κB pathway in AD model rats

The purpose of this study is to investigate the therapeutic effect of Qi Fu Yin (QFY) on Alzheimer's disease (AD) both computationally and experimentally. Network pharmacology analysis and molecular docking were conducted to identify potential targets and signaling pathways involved in QFY treating AD. Streptozotocin-induced AD rat model was used to verify important targets and predicted pathways. The components of QFY were identified using liquid chromatography-tandem mass spectrometry. The results indicate that the potential targets of QFY are highly enriched for anti-inflammatory pathways. Molecular docking analysis revealed stable structures formed between QFY's active compounds, including stigmasterol, β-sitosterol, and isorhamnetin, and the identified targets. In vivo, QFY improved cognitive memory in AD rats and reduced the mRNA expression levels of toll-like receptor 4 (TLR4), the receptor for advanced glycation end products (AGER), and the inflammatory factors interleukin-1β (IL-1β) and tumor necrosis factor-α (TNF-α) in the brains of AD rats. Furthermore, QFY effectively reduced nuclear translocation of nuclear factor-kappa B (NF-κB) and inhibited NF-κB and microglia activation. In conclusion, QFY can ameliorate neuroinflammation in AD model rats, partly via the inhibition of TLR4 and RAGE/NF-κB pathway and microglia activation, thereby enhancing learning and memory in AD model rats.

Roles of microglia in adult hippocampal neurogenesis in depression and their therapeutics

Adult hippocampal neurogenesis generates functional neurons from neural progenitor cells in the hippocampal dentate gyrus (DG) to complement and repair neurons and neural circuits, thus benefiting the treatment of depression. Increasing evidence has shown that aberrant microglial activity can disrupt the appropriate formation and development of functional properties of neurogenesis, which will play a crucial role in the occurrence and development of depression. However, the mechanisms of the crosstalk between microglia and adult hippocampal neurogenesis in depression are not yet fully understood. Therefore, in this review, we first introduce recent discoveries regarding the roles of microglia and adult hippocampal neurogenesis in the etiology of depression. Then, we systematically discuss the possible mechanisms of how microglia regulate adult hippocampal neurogenesis in depression according to recent studies, which involve toll-like receptors, microglial polarization, fractalkine-C-X3-C motif chemokine receptor 1, hypothalamic-pituitary-adrenal axis, cytokines, brain-derived neurotrophic factor, and the microbiota-gut-brain axis, etc. In addition, we summarize the promising drugs that could improve the adult hippocampal neurogenesis by regulating the microglia. These findings will help us understand the complicated pathological mechanisms of depression and shed light on the development of new treatment strategies for this disease.

Circadian Regulation of the Neuroimmune Environment Across the Lifespan: From Brain Development to Aging

Circadian clocks confer 24-h periodicity to biological systems, to ultimately maximize energy efficiency and promote survival in a world with regular environmental light cycles. In mammals, circadian rhythms regulate myriad physiological functions, including the immune, endocrine, and central nervous systems. Within the central nervous system, specialized glial cells such as astrocytes and microglia survey and maintain the neuroimmune environment. The contributions of these neuroimmune cells to both homeostatic and pathogenic demands vary greatly across the day. Moreover, the function of these cells changes across the lifespan. In this review, we discuss circadian regulation of the neuroimmune environment across the lifespan, with a focus on microglia and astrocytes. Circadian rhythms emerge in early life concurrent with neuroimmune sculpting of brain circuits and wane late in life alongside increasing immunosenescence and neurodegeneration. Importantly, circadian dysregulation can alter immune function, which may contribute to susceptibility to neurodevelopmental and neurodegenerative diseases. In this review, we highlight circadian neuroimmune interactions across the lifespan and share evidence that circadian dysregulation within the neuroimmune system may be a critical component in human neurodevelopmental and neurodegenerative diseases.

Targeting microbiota to alleviate the harm caused by sleep deprivation

Sleep deprivation has become a common health hazard, affecting 37-58% of the population and promoting the occurrence and development of many diseases. To date, effective treatment strategies are still elusive. Accumulating evidence indicates that modulating the intestinal microbiota harbors significant potential for alleviating the deleterious impacts of sleep deprivation. This paper first reviews the effects of sleep deprivation on gastrointestinal diseases, metabolic diseases, and neuropsychiatric diseases, discussing its specific mechanisms of influence. We then focus on summarizing existing interventions, including probiotics, melatonin, prebiotics, diet, and fecal microbiota transplantation (FMT). Finally, we have discussed the advantages and limitations of each strategy. Compared with other strategies, probiotics showed a high potential in alleviating sleep deprivation-related hazards due to their reduced risk and high security. We suggest that future research should focus on the specific mechanisms by which probiotics mitigate the harms of sleep deprivation, such insights may unveil novel pathways for treating diseases exacerbated by insufficient sleep.