The tired hippocampus: the molecular impact of sleep deprivation on hippocampal function

Sleep loss is a metabolic disorder

Sleep loss dysregulates cellular metabolism and energy homeostasis. Highly metabolically active cells, such as neurons, enter a catabolic state during periods of sleep loss, which consequently disrupts physiological functioning. Specific to the central nervous system, sleep loss results in impaired synaptogenesis and long-term memory, effects that are also characteristic of neurodegenerative diseases. In this review, we describe how sleep deprivation increases resting energy expenditure, leading to the development of a negative energy balance-a state with insufficient metabolic resources to support energy expenditure-in highly active cells like neurons. This disruption of energetic homeostasis alters the balance of metabolites, including adenosine, lactate, and lipid peroxides, such that energetically costly processes, such as synapse formation, are attenuated. During sleep loss, metabolically active cells shunt energetic resources away from those processes that are not acutely essential, like memory formation, to support cell survival. Ultimately, these findings characterize sleep loss as a metabolic disorder.

Choline alleviates cognitive impairment in sleep-deprived young mice via reducing neuroinflammation and altering phospholipidomic profile

Cognitive impairment resulting from insufficient sleep poses a significant public health concern, particularly in children. The effects and mechanisms of choline on cognitive impairment caused by sleep deprivation are unknown. Chronic sleep deprivation is induced in young mice in this study, followed by feeding diet containing 11.36 g/kg choline bitartrate. Choline supplementation significantly improves spatial learning ability. Functional MRI results reveal the hippocampus as a key region affected by sleep deprivation, where choline supplementation notably preserves hippocampal structural integrity and enhanced connectivity. Additionally, choline ameliorates hippocampal pathological injury, reduces blood-brain barrier permeability and serum brain injury biomarkers. Choline also reduces inflammation and oxidative stress biomarkers, and mitigates microglial activation in the hippocampus, which preserves synaptic plasticity. A key finding is the changes of hippocampal phospholipidomic profile along with cognitive function, and a total of 313 phospholipid molecules are identified. Choline increases the levels of total phospholipid and sub-classes (particularly PC), which are strongly correlated with reduced neuroinflammation and oxidative stress biomarkers, as well as improved cognitive outcomes. Furthermore, there are similar findings in some phospholipid molecules such as PC 36:1, PC O-33:0, PC p-38:3, PE 36:3, PE p-42:4 and PS 44:12. These findings highlight that choline alleviates cognitive impairment in sleep deprivation via reducing neuroinflammation and oxidative stress as well as altering phospholipidomic profile. This study suggests that choline could develop into functional food or medicine ingredient to prevent and treat cognitive impairment by sleep disturbances, particularly children and adolescents.

Association of Self-Perceived Fatigue, Muscle Fatigue, and Sleep Disorders with Cognitive Function in Older Adults: A Cross-Sectional Study

OBJECTIVES

Fatigue and sleep disorders are common geriatric conditions and are associated with an increased risk of cognitive decline. This study aimed to examine the relationships among self-perceived fatigue, objective muscle fatigue, sleep apnea risk, insomnia, and cognitive function, focusing on their associations with mild cognitive impairment (MCI).

DESIGN

Cross-sectional study.

SETTING AND PARTICIPANTS

The study involved 217 older adults (median age: 80 years, 65.6% women) from 2 residential care facilities in Vienna, Austria.

METHODS

Cognitive function was assessed with the Mini-Mental State Examination. Sleep quality and disturbances were evaluated using the Athens Insomnia Scale (AIS) and STOP-BANG questionnaire. Subjective fatigue was measured with the Multidimensional Fatigue Inventory, and objective muscle fatigue through 2 rounds of 10 maximal handgrip strength tests, separated by a 1-hour rest. Multivariable regression models adjusted for age, sex, comorbidities, sleep medication, and total number of medications were used to analyze associations among fatigue, sleep disturbance, and MCI.

RESULTS

Participants with MCI (n = 72) had significantly lower handgrip strength (median Fmax1: 18.75 kg vs 23.44 kg), higher muscle fatigue ratios (median: 1.40 vs 1.19), and poorer recovery ratios (median: 0.85 vs 1.01) compared with those without MCI (n = 145). Sleep disorders and fatigue measures were more common in those with MCI, with 80.6% reporting insomnia (AIS ≥6) compared with 21.4% in the cognitively intact group. Logistic regression showed that muscle fatigue combined with sleep apnea risk was associated with the highest odds of cognitive impairment [odds ratio (OR), 6.12; 95% CI, 2.77-13.51; adjusted OR, 3.02; 95% CI, 1.15-7.92]. Recovery capacity showed a positive association with cognitive function (β = 0.150, P < .05).

CONCLUSIONS AND IMPLICATIONS

Sleep apnea, muscle fatigue, and reduced recovery capacity are significantly associated with cognitive decline in older adults. Assessing these factors may help in identifying individuals at risk of cognitive impairment.

Does Obstructive sleep apnea mediate the risk of cognitive impairment by expanding the perivascular space?

BACKGROUND

Obstructive sleep apnea (OSA) is a neglected global health issue and when left untreated could lead to cognitive impairment (CI), one of the most burdensome outcomes of OSA. Enlarged perivascular spaces (EPVS), an imaging feature as well as a subtype of cerebral small vessel disease and integral part of CSVD, are associated with cognitive function, but the relationship between EPVS and CI is not well understood and by extension the correlation between OSA and EPVS, how CI develops under the joint impact of OSA and EPVS remains unclear. It is the goal of This study to explore the associations among OSA, EPVS, and CI.

METHODS

This cross-sectional study included 175 older adults with imaging features of EPVS with or without other CSVD subtype features by cranial magnetic resonance imaging between January 2021 and June 2023 at the Shanghai Fifth People's Hospital. We assessed OSA using polysomnography. Blood samples were collected to determine vascular risk factor indices. Cognitive scoring modalities included the Mini-Mental State Examination (MMSE) and Montreal Cognitive Assessment (MOCA). To explore the relationship among OSA, EPVS, and CI, we used single-factor analysis, multifactorial analysis, and receiver operating characteristic (ROC) curves.

RESULTS

A total of 136 participants were analyzed. In our statistical process, MMSE showed a more distinguished performance than MoCA. Participants with OSA had greater EPVS burdens in the midbrain (p < 0.001) and hippocampus (p < 0.001) and more serious CI (p = 0.001). OSA positively influenced EPVS in the midbrain (β = 0.052; 95% confidence interval [CI]: 0.006, 0.097; p = 0.026) and hippocampus (β = 0.190, 95% CI: 0.104, 0.275, p < 0.001). Moreover, the apnea-hypopnea index (AHI; β = -0.514; 95% CI: -0.077, -0.031; p < 0.001) negatively affected cognitive e function. With each increase in the AHI by 1 unit, the risk of CI increased by 12.0% (odds ratio = 1.120; 95%CI: 1.062, 1.181; p < 0.001). The AHI (sensitivity, 67.20%; specificity, 92.20%; area under the ROC curve, 0.828; p < 0.001) had a certain degree of accuracy in ruling out CI in the EPVS population, as calculated using the ROC curve.

CONCLUSIONS

We identified significant relations among OSA, EPVS, and CI. The AHI is a potential marker for estimating cognitive function in patients with EPVS.

Consuming 'God Juice': Using 'ethnopharmacological-connoisseurship' to situate trenbolone use and knowledge among image and performance enhancing drug communities

INTRODUCTION

Trenbolone, a potent anabolic-androgenic steroid (AAS), is used for its muscle growth benefits but poses significant health risks, including psychosocial issues. Existing research among humans is limited by lack of targeted investigation. This study addresses gaps in existing research by leveraging the ethnopharmacological expertise of trenbolone consumers. By engaging with the community's connoisseurship, we sought to enhance harm reduction strategies and foster collaboration between consumers, scholars and health practitioners.

METHODS

An international sample of trenbolone consumers (N = 30) were interviewed. Interviews explored trenbolone use, knowledge levels and harm reduction strategies. Analysis involved an iterative categorisation approach, incorporating the lead author's lived experience with trenbolone.

RESULTS

Participants described trenbolone as both a physical enhancer and a source of psychological boosts, tempered by adverse effects such as emotional volatility and intrusive thoughts. Despite warnings about its dangers the drug's allure was amplified by social media and community visibility. Consumers spoke of a developing connoisseur-like knowledge about trenbolone through personal and shared experiences. Through this collective expertise, they developed harm reduction strategies such as conservative dosing and regular health monitoring.

DISCUSSION AND CONCLUSIONS

This study demonstrates the importance of integrating ethnopharmacological-connoisseurship from the image and performance enhancing drug community to develop a contextually relevant understanding of AAS use-trenbolone being one of these. By elevating community insights, we advocate for a collaborative approach to harm reduction. Ultimately, we call for partnerships between researchers, health professionals and consumers to enhance health and reduce harm in image and performance enhancing drug communities.

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.

Effects of Quetiapine on Novelty-Related Object Recognition Memory and Hippocampal BDNF Level in Sleep-Deprived Rats

BACKGROUND

The underlying mechanism of quetiapine (QET) in treating cognitive impairment in sleep deprivation is unclear. The present study aimed to evaluate the effects of treatment with QET on novel object recognition and hippocampal (hippo) brain-derived neurotrophic factor (BDNF) levels in rats submitted to 72 h sleep deprivation (SD).

MATERIALS AND METHODS

A total of 42 adult male Wistar albino rats were assigned into six experimental groups: non-sleep-deprived (NSD) control, short-term control group (n = 7) received a single intraperitoneal (i.p.) injection 10 mg/kg QET of 1 mL saline (4 days) (NSD-STQET), long-term control group (n = 7) received single i.p. injection 10 mg/kg QET of 1 mL saline (30 days) (NSD-LTQET); 72 h sleep-deprived (SD) group, 72 h SD short-term group received short-term i.p. injection 10 mg/kg QET of either (n = 7) (SD-STQET), and 72 h SD long-term group received long-term i.p. injection 10 mg/kg QET of either (n = 7) QET (SD-LTQET). SD was performed using the modified multiple-platform technique in a water tank for 72 h. Additionally, we aim to reveal the consequences of 72 h SD and QET effects on memory processes with hippo BDNF levels by testing rats in the novel object recognition (NOR) test and ELISA method.

RESULTS

Long-term QET administration in healthy rats decreased NOR and BDNF protein expression in the hippocampus, as did 72 h SD. Long- and short-term QET administration reversed SD effects, but only short-term QET administration increased hippo BDNF.

CONCLUSION

These results suggest that the beneficial effects of QET on SD may be partly related to the upregulation of recognition memory and neuroprotective proteins such as BDNF. However, long-term QET treatment in the absence of a disease model may have the potential to negatively impact recognition memory and BDNF levels, which support synaptic plasticity and cognitive function.

Associations of accelerometer-measured physical activity, sedentary behaviour, and sleep with next-day cognitive performance in older adults: a micro-longitudinal study

BACKGROUND

Previous studies suggest short-term cognitive benefits of physical activity occurring minutes to hours after exercise. Whether these benefits persist the following day and the role of sleep is unclear. We examined associations of accelerometer-assessed physical activity, sedentary behaviour, and sleep with next-day cognitive performance in older adults.

METHODS

British adults aged 50-83 years (N = 76) without evidence of cognitive impairment or dementia wore accelerometers for eight days, and took daily cognitive tests of attention, memory, psychomotor speed, executive function, and processing speed. Physical behaviour (time spent in moderate-to-vigorous physical activity [MVPA], light physical activity [LPA], and sedentary behaviour [SB]) and sleep characteristics (overnight sleep duration, time spent in rapid eye movement [REM] sleep and slow wave sleep [SWS]) were extracted from accelerometers, with sleep stages derived using a novel polysomnography-validated machine learning algorithm. We used linear mixed models to examine associations of physical activity and sleep with next-day cognitive performance, after accounting for habitual physical activity and sleep patterns during the study period and other temporal and contextual factors.

RESULTS

An additional 30 min of MVPA on the previous day was associated with episodic memory scores 0.15 standard deviations (SD; 95% confidence interval = 0.01 to 0.29; p = 0.03) higher and working memory scores 0.16 SD (0.03 to 0.28; p = 0.01) higher. Each 30-min increase in SB was associated with working memory scores 0.05 SD (0.00 to 0.09) lower (p = 0.03); adjustment for sleep characteristics on the previous night did not substantively change these results. Independent of MVPA on the previous day, sleep duration ≥ 6 h (compared with < 6 h) on the previous night was associated with episodic memory scores 0.60 SD (0.16 to 1.03) higher (p = 0.008) and psychomotor speed 0.34 SD (0.04 to 0.65) faster (p = 0.03). Each 30-min increase in REM sleep on the previous night was associated with 0.13 SD (0.00 to 0.25) higher attention scores (p = 0.04); a 30-min increase in SWS was associated with 0.17 SD (0.05 to 0.29) higher episodic memory scores (p = 0.008).

CONCLUSIONS

Memory benefits of MVPA may persist for 24 h; longer sleep duration, particularly more time spent in SWS, could independently contribute to these benefits.

Investigation of the structural changes in the hippocampus and prefrontal cortex using FTIR spectroscopy in sleep deprived mice

Sleep is a basic, physiological requirement for living things to survive and is a process that covers one third of our lives. Melatonin is a hormone that plays an important role in the regulation of sleep. Sleep deprivation affect brain structures and functions. Sleep deprivation causes a decrease in brain activity, with particularly negative effects on the hippocampus and prefrontal cortex. Despite the essential role of protein and lipids vibrations, polysaccharides, fatty acid side chains functional groups, and ratios between amides in brain structures and functions, the brain chemical profile exposed to gentle handling sleep deprivation model versus Melatonin exposure remains unexplored. Therefore, the present study, aims to investigate a molecular profile of these regions using FTIR spectroscopy measurement's analysis based on lipidomic approach with chemometrics and multivariate analysis to evaluate changes in lipid composition in the hippocampus, prefrontal regions of the brain. In this study, C57BL/6J mice were randomly assigned to either the control or sleep deprivation group, resulting in four experimental groups: Control (C) (n = 6), Control + Melatonin (C + M) (n = 6), Sleep Deprivation (S) (n = 6), and Sleep Deprivation + Melatonin (S + M) (n = 6). Interventions were administered each morning via intraperitoneal injections of melatonin (10 mg/kg) or vehicle solution (%1 ethanol + saline), while the S and S + M groups underwent 6 h of daily sleep deprivation from using the Gentle Handling method. All mice were individually housed in cages with ad libitum access to food and water within a 12-hour light-dark cycle. Results presented that the brain regions affected by insomnia. The structure of phospholipids, changed. Yet, not only changes in lipids but also in amides were noticed in hippocampus and prefrontal cortex tissues. Additionally, FTIR results showed that melatonin affected the lipids as well as the amides fraction in cortex and hippocampus collected from both control and sleep deprivation groups.

Impact of USMLE Step 1 transition to pass/fail scoring system on medical students' anxiety, sleep quality, and burnout

INTRODUCTION

Originally designed to evaluate the application of foundational scientific knowledge in clinical contexts, the United States Medical License Exam (USMLE) Step 1 evolved into a comparative tool for assessing candidates with similar educational foundations. This transition heightened the pressure on medical students to excel in the exam. In response, collaborative efforts involving the National Board of Medical Examiners prompted a change from reporting scores to a pass/fail system. The true impact of this shift remains insufficiently explored. This study aims to assess the emotional toll - encompassing burnout, anxiety, depression, and sleep quality - experienced prior to taking the Step 1 exam. Additionally, it aims to uncover potential gender-based disparities in perceived anxiety and depression.

METHODS

The study encompasses the entirety of third-year medical students at Drexel University College of Medicine, who were invited to participate in a comprehensive survey. Drawing from retrospection, the survey relies on self-reported data regarding anxiety, depression, sleep quality, and burnout. Data compilation was anonymized and executed via Qualtrics platform.

RESULTS

A total of 102 medical students completed the survey, with a 97% pass rate for the USMLE Step 1. Despite their excellent performance, 75% of students reported inadequate sleep quality, and 68% exhibited mild to moderate anxiety levels. Among them, a higher percentage of females (83%) experienced anxiety compared to their male counterparts (50%). Furthermore, 66% of students felt that their commitment to education exceeded what was reasonable for their well-being.

CONCLUSIONS

The transition from traditional scoring to a pass/fail system was ostensibly intended to enhance the mental well-being of medical students. Nevertheless, our findings underscore that students continue to endure heightened levels of stress, anxiety, and burnout during the pivotal month leading up to the Step 1 examination.

Electroacupuncture inhibits hippocampal oxidative stress and autophagy in sleep-deprived rats through the protein kinase B and mechanistic target of rapamycin signaling pathway

OBJECTIVE

To investigate the effects of acupuncture on learning and memory impairment, oxidative stress and autophagy induced by sleep depriv ation in rats, and to analyze the related mechanism.

METHODS

Thirty Wistar rats were randomly divided into a normal group, sleep deprivation group and acupuncture group. The rat model of sleep deprivation was established by a modified multiplatform sleep deprivation method. The Baihui (GV20), Shenmen (HT7) and Sanyinjiao (SP6) acupoints of rats were located to give electroacupuncture (density wave, frequency 20 Hz, intensity 1 mA) to maintain the needle feeling, and to keep the needle for 15 min and continuous acupuncture for 7 d. The spatial learning and memory abilities of the rats were detected by the water maze test. The content of malondialdehyde (MDA) and the activities of superoxide dismutase (SOD) and glutathione peroxidase (GPX) in the brain were detected by an assay kit, and the autophagy related proteins light chain 3 alpha (LC3A), light chain 3 beta (LC3B) and Beclin 1 and the activation of the protein kinase B (PKB/AKT) and mechanistic target of rapamycin (mTOR) signaling pathway in the rat's brain were detected by Western blotting.

RESULTS

Compared with the normal group, the time spent in the target quadrant (P < 0.05) and the number of times entering the target quadrant (P < 0.05) in the rats of sleep deprivation group were significantly reduced, and the content of MDA was significantly increased (P < 0.01), while the activities of SOD and GPX (P < 0.01) in the brain were significantly decreased, and LC3A Ⅱ/Ⅰ, LC3B Ⅱ/Ⅰ and Beclin 1 increased significantly (P < 0.01), while p-AKT (ser473)/AKT, p-mTOR (ser2448)/mTOR and p-p70s6K (thr389)/p70S6 decreased significantly (P < 0.01). Compared with the sleep deprivation group, the time spent in the target quadrant and the times of entering the target quadrant (P < 0.05) in the rats of acupuncture group after 7 d of treatment were significantly increased, Additionally, the content of MDA was significantly decreased (P < 0.05), while the activities of SOD and GPX (P < 0.05) in the brain were significantly increased. Moreover, the levels of LC3A Ⅱ/Ⅰ, LC3BⅡ/Ⅰ and Beclin 1 decreased significantly (P < 0.05), and that of p-AKT (ser473)/AKT, p-mTOR (ser2448)/mTOR and p-p70s6K (thr389)/p70s6k increased significantly (P < 0.05).

CONCLUSION

Acupuncture can significantly improve the learning and memory damage caused by sleep deprivation and inhibit oxidative stress and autophagy, and its effect is related to the activation of AKT/mTOR signaling.

The Mixed Role of Sleep and Time of Day in Working Memory Performance of Older Adults with Mild Cognitive Impairment

The importance of night sleep for maintaining good physical and cognitive health is well documented as well as its negative changes during aging. Since Mild Cognitive Impairment (MCI) patients bear additional disturbances in their sleep, this study aimed at examining whether there are potential mixed effects of sleep and afternoon time of day (ToD) on the storage, processing, and updating components of working memory (WM) capacity in older adults with MCI. In particular, the study compared patients' performance in the three working memory components, in two-time conditions: "early in the morning and after night sleep", and "in the afternoon and after many hours since night sleep". The Working Memory Capacity & Updating Task from the R4Alz battery was administered twice to 50 older adults diagnosed with MCI. The repeated measures analysis showed statistically significant higher performance in the morning condition for the working memory updating component (p < 0.001). Based on the findings, it seems that the afternoon ToD condition negatively affects tasks with high cognitive demands such as the WM updating task in MCI patients. These findings could determine the optimal timing for cognitive rehabilitation programs for MCI patients and the necessary sleep duration when they are engaged in cognitively demanding daily activities.

Acute sleep deprivation in mice generates protein pathology consistent with neurodegenerative diseases

Introduction

Insufficient or disturbed sleep is strongly associated with adverse health conditions, including various neurodegenerative disorders. While the relationship between sleep and neurodegenerative disease is likely bidirectional, sleep disturbances often predate the onset of other hallmark clinical symptoms. Neuronal waste clearance is significantly more efficient during sleep; thus, disturbed sleep may lead to the accumulation of neuronal proteins that underlie neurodegenerative diseases. Key pathological features of neurodegenerative diseases include an accumulation of misfolded or misprocessed variants of amyloid beta (Aβ), tau, alpha synuclein (α-syn), and TarDNA binding protein 43 (TDP-43). While the presence of fibrillar protein aggregates of these neuronal proteins are characteristic of neurodegenerative diseases, the presence of small soluble toxic oligomeric variants of these different proteins likely precedes the formation of the hallmark aggregates.

Methods

We hypothesized that sleep deprivation would lead to accumulation of toxic oligomeric variants of Aβ, tau, α-syn, and TDP-43 in brain tissue of wild-type mice. Adult mice were subjected to 6 h of sleep deprivation (zeitgeber 0-6) for 5 consecutive days or were left undisturbed as controls. Following sleep deprivation, brains were collected, and protein pathology was assessed in multiple brain regions using an immunostain panel of reagents selectively targeting neurodegenerative disease-related variants of Aβ, tau, α-syn, and TDP-43.

Results

Overall, sleep deprivation elevated levels of all protein variants in at least one of the brain regions of interest. The reagent PDTDP, targeting a TDP-43 variant present in Parkinson's disease, was elevated throughout the brain. The cortex, caudoputamen, and corpus callosum brain regions showed the highest accumulation of pathology following sleep deprivation.

Discussion

These data provide a direct mechanistic link between sleep deprivation, and the hallmark protein pathologies of neurodegenerative diseases, such as Alzheimer's and Parkinson's diseases.

Long-lasting effects of disturbing the circadian rhythm or sleep in adolescence

Circadian rhythms are endogenous, near 24-hour rhythms that regulate a multitude of biological and behavioral processes across the diurnal cycle in most organisms. Over the lifespan, a bell curve pattern emerges in circadian phase preference (i.e. chronotype), with children and adults generally preferring to wake earlier and fall asleep earlier, and adolescents and young adults preferring to wake later and fall asleep later than their adult counterparts. This well-defined shift speaks to the variability of circadian rhythmicity over the lifespan and the changing needs and demands of the brain as an organism develops, particularly in the adolescent period. Indeed, adolescence is known to be a critical period of development during which dramatic neuroanatomical changes are occurring to allow for improved decision-making. Due to the large amount of re-structuring occurring in the adolescent brain, circadian disruptions during this period could have adverse consequences that persist across the lifespan. While the detrimental effects of circadian disruptions in adults have been characterized in depth, few studies have longitudinally assessed the potential long-term impacts of circadian disruptions during adolescence. Here, we will review the evidence that disruptions in circadian rhythmicity during adolescence have effects that persist into adulthood. As biological and social time often conflict in modern society, with school start times misaligned with adolescents' endogenous rhythms, it is critical to understand the long-term impacts of disrupted circadian rhythmicity in adolescence.

Hypnotic treatment improves sleep architecture and EEG disruptions and rescues memory deficits in a mouse model of fragile X syndrome

Fragile X syndrome (FXS) is associated with disrupted cognition and sleep abnormalities. Sleep loss negatively impacts cognitive function, and one untested possibility is that disrupted cognition in FXS is exacerbated by abnormal sleep. We tested whether ML297, a hypnotic acting on G-protein-activated inward-rectifying potassium (GIRK) channels, could reverse sleep phenotypes and disrupted memory in Fmr1-/y mice. Fmr1-/y mice exhibit reduced non-rapid eye movement (NREM) sleep and fragmented NREM architecture, altered sleep electroencephalogram (EEG) oscillations, and reduced EEG coherence between cortical areas; these are partially reversed following ML297 administration. Treatment following contextual fear or spatial learning restores disrupted memory consolidation in Fmr1-/y mice. During memory recall, Fmr1-/y mice show an altered balance of activity among hippocampal principal neurons vs. parvalbumin-expressing interneurons; this is partially reversed by ML297. Because sleep disruption could impact neurophysiological phenotypes in FXS, augmenting sleep may improve disrupted cognition in this disorder.

Preoperative recovery sleep ameliorates postoperative cognitive dysfunction aggravated by sleep fragmentation in aged mice by enhancing EEG delta-wave activity and LFP theta oscillation in hippocampal CA1

Sleep fragmentation (SF) is a common sleep problem experienced during the perioperative period by older adults, and is associated with postoperative cognitive dysfunction (POCD). Increasing evidence indicates that delta-wave activity during non-rapid eye movement (NREM) sleep is involved in sleep-dependent memory consolidation and that hippocampal theta oscillations are related to spatial exploratory memory. Recovery sleep (RS), a self-regulated state of sleep homeostasis, enhances delta-wave power and memory performance in sleep-deprived older mice. However, it remains unclear whether RS therapy has a positive effect on cognitive changes following SF in older mouse models. Therefore, this study aimed to explore whether preoperative RS can alleviate cognitive deficits in aged mice with SF. A model of preoperative 24-h SF combined with exploratory laparotomy-induced POCD was established in 18-month-old mice. Aged mice were treated with preoperative 6-h RS following SF and postoperative 6-h RS following surgery, respectively. The changes in hippocampus-dependent cognitive function were investigated using behavioral tests, electroencephalography (EEG), local field potential (LFP), magnetic resonance imaging, and neuromorphology. Mice that underwent 24-h SF combined with surgery exhibited severe spatial memory impairment; impaired cognitive performance could be alleviated by preoperative RS treatment. In addition, preoperative RS increased NREM sleep; enhanced EEG delta-wave activity and LFP theta oscillation in the hippocampal CA1; and improved hippocampal perfusion, microstructural integrity, and neuronal damage. Taken together, these results provide evidence that preoperative RS may ameliorate the severity of POCD aggravated by SF by enhancing delta slow-wave activity and hippocampal theta oscillation, and by ameliorating the reduction in regional cerebral blood flow and white matter microstructure integrity in the hippocampus.

Sleep loss diminishes hippocampal reactivation and replay

Memories benefit from sleep1, and the reactivation and replay of waking experiences during hippocampal sharp-wave ripples (SWRs) are considered to be crucial for this process2. However, little is known about how these patterns are impacted by sleep loss. Here we recorded CA1 neuronal activity over 12 h in rats across maze exploration, sleep and sleep deprivation, followed by recovery sleep. We found that SWRs showed sustained or higher rates during sleep deprivation but with lower power and higher frequency ripples. Pyramidal cells exhibited sustained firing during sleep deprivation and reduced firing during sleep, yet their firing rates were comparable during SWRs regardless of sleep state. Despite the robust firing and abundance of SWRs during sleep deprivation, we found that the reactivation and replay of neuronal firing patterns was diminished during these periods and, in some cases, completely abolished compared to ad libitum sleep. Reactivation partially rebounded after recovery sleep but failed to reach the levels found in natural sleep. These results delineate the adverse consequences of sleep loss on hippocampal function at the network level and reveal a dissociation between the many SWRs elicited during sleep deprivation and the few reactivations and replays that occur during these events.

Retuning of hippocampal representations during sleep

Hippocampal representations that underlie spatial memory undergo continuous refinement following formation1. Here, to track the spatial tuning of neurons dynamically during offline states, we used a new Bayesian learning approach based on the spike-triggered average decoded position in ensemble recordings from freely moving rats. Measuring these tunings, we found spatial representations within hippocampal sharp-wave ripples that were stable for hours during sleep and were strongly aligned with place fields initially observed during maze exploration. These representations were explained by a combination of factors that included preconfigured structure before maze exposure and representations that emerged during θ-oscillations and awake sharp-wave ripples while on the maze, revealing the contribution of these events in forming ensembles. Strikingly, the ripple representations during sleep predicted the future place fields of neurons during re-exposure to the maze, even when those fields deviated from previous place preferences. By contrast, we observed tunings with poor alignment to maze place fields during sleep and rest before maze exposure and in the later stages of sleep. In sum, the new decoding approach allowed us to infer and characterize the stability and retuning of place fields during offline periods, revealing the rapid emergence of representations following new exploration and the role of sleep in the representational dynamics of the hippocampus.

Urolithin A Prevents Sleep-deprivation-induced Neuroinflammation and Mitochondrial Dysfunction in Young and Aged Mice

Sleep deprivation (SD) has reached epidemic proportions worldwide and negatively affects people of all ages. Cognitive impairment induced by SD involves neuroinflammation and mitochondrial dysfunction, but the underlying mechanisms are largely unknown. Urolithin A (UA) is a natural compound that can reduce neuroinflammation and improve mitochondrial health, but its therapeutic effects in a SD model have not yet been studied. Young (3-months old) and aged (12-months old) mice were sleep deprived for 24 h, and UA (2.5 mg/kg or 10 mg/kg) was injected intraperitoneally for 7 consecutive days before the SD period. Immunofluorescent staining, western blotting, and RT-PCR were employed to evaluate levels of proteins involved in neuroinflammation and mitochondrial function. Transmission electron microscope and Golgi-Cox staining were used to evaluate mitochondrial and neuronal morphology, respectively. Finally, contextual fear conditioning and the Morris water maze test were conducted to assess hippocampal learning and memory. In the hippocampus of young (3 months-old) and aged (12 months-old) mice subjected to 24 h SD, pretreatment with UA prevented the activation of microglia and astrocytes, NF-κB-NLRP3 signaling and IL-1β, IL6, TNF-α cytokine production, thus ameliorating neuroinflammation. Furthermore, UA also attenuated SD-induced mitochondrial dysfunction, normalized autophagy and mitophagy and protected hippocampal neuronal morphology. Finally, UA prevented SD-induced hippocampal memory impairment. Cumulatively, the results show that UA imparts cognitive protection by reducing neuroinflammation and enhancing mitochondrial function in SD mice. This suggests that UA shows promise as a therapeutic for the treatment of SD-induced neurological disorders.

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.

Activation of the Hippocampal DRD2 Alleviates Neuroinflammation, Synaptic Plasticity Damage and Cognitive Impairment After Sleep Deprivation

Sleep loss is commonplace nowadays and profoundly impacts cognition. Dopamine receptor D2 (DRD2) makes a specific contribution to cognition, although the precise mechanism underlying how DRD2 affects the cognitive process after sleep deprivation remains unclear. Herein, we observed cognitive impairment and impaired synaptic plasticity, including downregulation of synaptophysin and PSD95, decreased postsynaptic density thickness, neuron complexity, and spine density in chronic sleep restriction (CSR) mice. We also observed downregulated hippocampal DRD2 and Cryab expression in the CSR mice. Meanwhile, NF-κB translocation from the cytoplasm to the nucleus occurred, indicating that neuroinflammation ensued. However, hippocampal delivery of the DRD2 agonist quinpirole effectively rescued these changes. In vitro, quinpirole treatment significantly decreased the release of proinflammatory cytokines in microglial supernatant, indicating a potential anti-neuroinflammatory effect of Drd2/Cryab/NF-κB in CSR mice. Our study provided the evidence that activation of the Drd2 may relieve neuroinflammation and improve sleep deprivation-induced cognitive deficits.

[Effect of Sleep Deprivation on the Metabolism of Hippocampal Amino Acids and Monoamine Neurotransmitters in Mice and Their Behaviors]

Objective

To investigate the effect of sleep deprivation on the metabolism of the hippocampal region in mice.

Methods

The mice were randomly assigned to three groups, a control group, a 24-h sleep deprivation (SD) group, and a 48-h SD group. Each group had 10 mice. The sleep deprivation model was induced by the modified multiple platform method. The mice's anxiety-like behaviors were assessed with the open field test (OFT) and their depression-like behaviors were assessed with the sucrose preference test (SPT), the forced swimming test (FST), and tail suspension test (TST). High performance liquid chromatography (HPLC) was performed to determine the levels of 6 monoamine neurotransmitters, including 5-hydroxytryptamine (5-HT), norepinephrine (NE), dopamine (DA), gamma-aminobutyric acid (GABA), 5-dihydroxyphenylacetic acid (5-DOPAC), and homovanillic acid (HVA), and 4 amino acids, including glutamic acid (Glu), aspartic acid (Asp), serine (Ser), and taurine (Tau), in the hippocampal region. Immunofluorescence staining was performed to examine the expression of glial cells in the hippocampal region of the mice. The main indicators measured were the levels of monoamine neurotransmitters and amino acids.

Results

According to the results of the behavioral analysis, in comparison with the findings for the control group, the 24-h SD mice exhibited increased consumption of sucrose in SFT, significantly decreased total immobility time in FST and TST, and increased total distance covered in OFT, while the 48-h SD mice showed decreased consumption of sucrose in SFT, prolonged total immobility time in FST and TST, and decreased total distance covered in OFT. The results of the HPLC analysis of the monoamine neurotransmitter showed that 24-h SD mice had in their hippocampal region increased levels of DA (P<0.001) and NE (P<0.01) and decreased levels of GABA (P<0.05) in comparison with those of the control mice, while their 5-HT, 5-DOPAC, and HVA levels were not significantly different from those of the control mice. In comparison with those of the control mice, the 48-h SD mice had, in their hippocampal region, decreased levels of 5-HT and NE (all P<0.05), decreased DA (P<0.01), and increased level of GABA (P<0.01), while the levels of 5-DOPAC and HAV were not significantly different. The 48-h SD group showed a significant decrease in the levels of Tau and Glu in comparison with those of the 24-h SD group (all P<0.05). According to the results of immunofluorescence assay, there was no significant difference between the control group and the 24-h SD group in the cell count of glial fibrillary acidic protein (GFAP)-positive cells, while a decline in GFAP-positive cells in comparison with that of the control group was observed in the 48-h SD group.

Conclusion

SD of 24 hours may induce anxiety-like behavioral changes in mice by activating their hippocampal glial cells, upregulating the levels of 5-HT, DA, and NE, and increasing the levels of Glu and Tau in the hippocampal region. SD of 48 hours may induce depression-like behavioral changes in mice by inhibiting the activation of glial cells in the hippocampal region and regulating in the opposite direction the levels of the above-mentioned monoamine neurotransmitters and amino acids in the hippocampal region.

Hippocampal Malrotation Presenting With Treatment-Resistant Insomnia: A Case Report

A frequent complaint in medical settings is insomnia. Chronic insomnia is defined as the occurrence of sleep disturbance symptoms for a period of three months, three times per week, and in conjunction with at least one daytime symptom. In the case study, a young man with a documented seizure disorder underwent a thorough evaluation for chronic sleeplessness. Electroencephalograms, sleep investigations, and drug reviews were unsuccessful in determining the cause. Nonetheless, it was found that there was bilateral hippocampal malrotation. This link is distinct and hasn't been mentioned as a possible cause before.

Gallic Acid Ameliorates Cognitive Impairment Caused by Sleep Deprivation through Antioxidant Effect

Sleep deprivation (SD) has a profound impact on the central nervous system, resulting in an array of mood disorders, including depression and anxiety. Despite this, the dynamic alterations in neuronal activity during sleep deprivation have not been extensively investigated. While some researchers propose that sleep deprivation diminishes neuronal activity, thereby leading to depression. Others argue that short-term sleep deprivation enhances neuronal activity and dendritic spine density, potentially yielding antidepressant effects. In this study, a two-photon microscope was utilized to examine the calcium transients of anterior cingulate cortex (ACC) neurons in awake SD mice in vivo at 24-hour intervals. It was observed that SD reduced the frequency and amplitude of Ca2+ transients while increasing the proportions of inactive neurons. Following the cessation of sleep deprivation, neuronal calcium transients demonstrated a gradual recovery. Moreover, whole-cell patch-clamp recordings revealed a significant decrease in the frequency of spontaneous excitatory post-synaptic current (sEPSC) after SD. The investigation also assessed several oxidative stress parameters, finding that sleep deprivation substantially elevated the level of malondialdehyde (MDA), while simultaneously decreasing the expression of Nuclear Factor erythroid 2-Related Factor 2 (Nrf2) and activities of Superoxide dismutase (SOD) in the ACC. Importantly, the administration of gallic acid (GA) notably mitigated the decline of calcium transients in ACC neurons. GA was also shown to alleviate oxidative stress in the brain and improve cognitive impairment caused by sleep deprivation. These findings indicate that the calcium transients of ACC neurons experience a continuous decline during sleep deprivation, a process that is reversible. GA may serve as a potential candidate agent for the prevention and treatment of cognitive impairment induced by sleep deprivation.

Efficacy of electroacupuncture stimulating Shenmen (HT7), Baihui (GV20), Sanyinjiao (SP6) on spatial learning and memory deficits in rats with insomnia induced by para-chlorophenylalanine: a single acupoint combined acupoints

OBJECTIVE

To investiage the effect of electroacupuncture (EA) at a single acupoint of Shenmen (HT7), Baihui (GV20), Sanyinjiao (SP6) and at combined acupoints of Shenmen (HT7) and Baihui (GV20) and Sanyinjiao (SP6) on the PKA/CREB and BDNF/TrkB signaling, as well as neuroapoptosis and neurogenesis in hippocampus and elucidate the underlying mechanism of single and combined acupoints on ameliorating spatial learning and memory deficits in a rat model of primary insomnia.

METHODS

Primary insomnia was modeled by intraperitoneal injection of para-chlorophenylalanine (PCPA) once daily for 2 d. EA was applied at Shenmen (HT7), Baihui (GV20), Sanyinjiao (SP6), or Shenmen (HT7) + Baihui (GV20) + Sanyinjiao (SP6) (combined) for 30 min daily for 4 d. Spatial learning and memory function was evaluated by the Morris water maze (MWM) test. Protein expressions of hippocampal cAMP-dependent protein kinase (PKA)-Cβ, phosphorylated cAMP-responsive element-binding protein (p-CREB), brain-derived neurotrophic factor (BDNF), and tyrosine kinase receptor B (TrkB) were evaluated by Western blotting. Neuronal apoptosis in the hippocampus was detected with the transferase-mediated dUTP-X nick end labeling assay. Endogenous neurogenesis was examined with bromodeoxyuridine staining. The MWM test and hippocampal p-CREB, BDNF, and TrkB protein levels in the combined acupoints group were evaluated after the administration of a PKA-selective inhibitor (H89).

RESULTS

Spatial learning and memory were significantly impaired in rats with insomnia. The spatial learning deficits were ameliorated in the Shenmen (HT7), Baihui (GV20), Sanyinjiao (SP6), and combined groups; this improvement was significantly greater in the combined group than the single acupoint groups. The spatial memory impairment was improved in the combined, Baihui (GV20), and Shenmen (HT7) groups, but not the Sanyinjiao (SP6) group. The expressions of PKA-Cβ, p-CREB, BDNF, and TrkB were decreased in rats with insomnia. All these proteins were significantly upregulated in the combined group. PKA/p-CREB protein levels were elevated in the Baihui (GV20) and Shenmen (HT7) groups, whereas BDNF/TrkB expression was upregulated in the Sanyinjiao (SP6) group. The staining results showed significant attenuation of hippocampal cell apoptosis and increased numbers of proliferating cells in the combined group, whereas the single acupoint groups only showed decreased numbers of apoptotic cells. In the combined group, the PKA inhibitor reversed the improvement of spatial memory and upregulation of p-CREB expression caused by EA, but did not affect its activation of BDNF/TrkB signaling.

CONCLUSIONS

EA at the single acupoints Baihui (GV20), Shenmen (HT7), or Sanyinjiao (SP6) had an ameliorating effect on the spatial learning and memory deficits induced by insomnia. EA at combined acupoints exerted a synergistic effect on the improvements in spatial learning and memory impairment in rats with insomnia by upregulating the hippocampal PKA/CREB and BDNF/TrkB signaling, facilitating neurogenesis, and inhibiting neuronal apoptosis. These findings indicate that EA at combined acupoints [(Baihui (GV20), Shenmen (HT7), and Sanyinjiao (SP6)] achieves a more pronounced regulation of hippocampal neuroplasticity than EA at single acupoints, which may partly explain the underlying mechanisms by which EA at combined acupoints exerts a better ameliorative effect on the cognitive dysfunction caused by insomnia.

Hypnotic treatment reverses NREM sleep disruption and EEG desynchronization in a mouse model of Fragile X syndrome to rescue memory consolidation deficits

Fragile X syndrome (FXS) is a highly-prevalent genetic cause of intellectual disability, associated with disrupted cognition and sleep abnormalities. Sleep loss itself negatively impacts cognitive function, yet the contribution of sleep loss to impaired cognition in FXS is vastly understudied. One untested possibility is that disrupted cognition in FXS is exacerbated by abnormal sleep. We hypothesized that restoration of sleep-dependent mechanisms could improve functions such as memory consolidation in FXS. We examined whether administration of ML297, a hypnotic drug acting on G-protein-activated inward-rectifying potassium channels, could restore sleep phenotypes and improve disrupted memory consolidation in Fmr1 -/y mice. Using 24-h polysomnographic recordings, we found that Fmr1 -/y mice exhibit reduced non-rapid eye movement (NREM) sleep and fragmented NREM sleep architecture, alterations in NREM EEG spectral power (including reductions in sleep spindles), and reduced EEG coherence between cortical areas. These alterations were reversed in the hours following ML297 administration. Hypnotic treatment following contextual fear or spatial learning also ameliorated disrupted memory consolidation in Fmr1 -/y mice. Hippocampal activation patterns during memory recall was altered in Fmr1 -/y mice, reflecting an altered balance of activity among principal neurons vs. parvalbumin-expressing (PV+) interneurons. This phenotype was partially reversed by post-learning ML297 administration. These studies suggest that sleep disruption could have a major impact on neurophysiological and behavioral phenotypes in FXS, and that hypnotic therapy may significantly improve disrupted cognition in this disorder.

Sleep is required to consolidate odor memory and remodel olfactory synapses

Animals with complex nervous systems demand sleep for memory consolidation and synaptic remodeling. Here, we show that, although the Caenorhabditis elegans nervous system has a limited number of neurons, sleep is necessary for both processes. In addition, it is unclear if, in any system, sleep collaborates with experience to alter synapses between specific neurons and whether this ultimately affects behavior. C. elegans neurons have defined connections and well-described contributions to behavior. We show that spaced odor-training and post-training sleep induce long-term memory. Memory consolidation, but not acquisition, requires a pair of interneurons, the AIYs, which play a role in odor-seeking behavior. In worms that consolidate memory, both sleep and odor conditioning are required to diminish inhibitory synaptic connections between the AWC chemosensory neurons and the AIYs. Thus, we demonstrate in a living organism that sleep is required for events immediately after training that drive memory consolidation and alter synaptic structures.

Atypical hypnotic compound ML297 restores sleep architecture immediately following emotionally valenced learning, to promote memory consolidation and hippocampal network activation during recall

Sleep plays a critical role in consolidating many forms of hippocampus-dependent memory. While various classes of hypnotic drugs have been developed in recent years, it remains unknown whether, or how, some of them affect sleep-dependent memory consolidation mechanisms. We find that ML297, a recently developed candidate hypnotic agent targeting a new mechanism (activating GIRK1/2-subunit containing G-protein coupled inwardly rectifying potassium [GIRK] channels), alters sleep architecture in mice over the first 6 hr following a single-trial learning event. Following contextual fear conditioning (CFC), ML297 reversed post-CFC reductions in NREM sleep spindle power and REM sleep amounts and architecture, renormalizing sleep features to what was observed at baseline, prior to CFC. Renormalization of post-CFC REM sleep latency, REM sleep amounts, and NREM spindle power were all associated with improved contextual fear memory (CFM) consolidation. We find that improvements in CFM consolidation due to ML297 are sleep-dependent, and are associated with increased numbers of highly activated dentate gyrus (DG), CA1, and CA3 neurons during CFM recall. Together our findings suggest that GIRK1/2 channel activation restores normal sleep architecture- including REM sleep, which is normally suppressed following CFC-and increases the number of hippocampal neurons incorporated into the CFM engram during memory consolidation.

Chrysanthemum morifolium and Its Bioactive Substance Enhanced the Sleep Quality in Rodent Models via Cl- Channel Activation

Dried Chrysanthemum morifolium (Chry) flowers have been used in Korea as a traditional insomnia treatment. In this study, the sleep-promoting activity and improving sleep quality of Chry extract (ext) and its active substance linarin were analyzed by pentobarbital-induced sleep experiment in mice and electroencephalography (EEG), electromyogram (EMG) analysis in rats. In a dose-dependent manner, Chry ext and linarin promoted longer sleep duration in the pentobarbital-induced sleep test compared to pentobarbital-only groups at both hypnotic and subhypnotic doses. Chry ext administration also significantly improved sleep quality, as seen in the relative power of low-frequency (delta) waves when compared with the control group. Linarin increased Cl- uptake in the SH-SY5Y human cell line and chloride influx was reduced by bicuculline. After administration of Chry ext, the hippocampus, frontal cortex, and hypothalamus from rodents were collected and blotted for glutamic acid decarboxylase (GAD)65/67 and gamma-aminobutyric acid (GABA)A receptors subunit expression levels. The expression of α1-subunits, β2-subunits, and GAD65/67 of the GABAA receptor was modulated in the rodent brain. In conclusion, Chry ext augments pentobarbital-induced sleep duration and enhances sleep quality in EEG waves. These effects might be due to the activation of the Cl- channel.

Sleep loss diminishes hippocampal reactivation and replay

Memories benefit from sleep, and sleep loss immediately following learning has a negative impact on subsequent memory storage. Several prominent hypotheses ascribe a central role to hippocampal sharp-wave ripples (SWRs), and the concurrent reactivation and replay of neuronal patterns from waking experience, in the offline memory consolidation process that occurs during sleep. However, little is known about how SWRs, reactivation, and replay are affected when animals are subjected to sleep deprivation. We performed long duration (~12 h), high-density silicon probe recordings from rat hippocampal CA1 neurons, in animals that were either sleeping or sleep deprived following exposure to a novel maze environment. We found that SWRs showed a sustained rate of activity during sleep deprivation, similar to or higher than in natural sleep, but with decreased amplitudes for the sharp-waves combined with higher frequencies for the ripples. Furthermore, while hippocampal pyramidal cells showed a log-normal distribution of firing rates during sleep, these distributions were negatively skewed with a higher mean firing rate in both pyramidal cells and interneurons during sleep deprivation. During SWRs, however, firing rates were remarkably similar between both groups. Despite the abundant quantity of SWRs and the robust firing activity during these events in both groups, we found that reactivation of neurons was either completely abolished or significantly diminished during sleep deprivation compared to sleep. Interestingly, reactivation partially rebounded upon recovery sleep, but failed to reach the levels characteristic of natural sleep. Similarly, the number of replays were significantly lower during sleep deprivation and recovery sleep compared to natural sleep. These results provide a network-level account for the negative impact of sleep loss on hippocampal function and demonstrate that sleep loss impacts memory storage by causing a dissociation between the amount of SWRs and the replays and reactivations that take place during these events.

Recovering object-location memories after sleep deprivation-induced amnesia

It is well established that sleep deprivation after learning impairs hippocampal memory processes and can cause amnesia. It is unknown, however, whether sleep deprivation leads to the loss of information or merely the suboptimal storage of information that is difficult to retrieve. Here, we show that hippocampal object-location memories formed under sleep deprivation conditions can be successfully retrieved multiple days following training, using optogenetic dentate gyrus (DG) memory engram activation or treatment with the clinically approved phosphodiesterase 4 (PDE4) inhibitor roflumilast. Moreover, the combination of optogenetic DG memory engram activation and roflumilast treatment, 2 days following training and sleep deprivation, made the memory more persistently accessible for retrieval even several days later (i.e., without further optogenetic or pharmacological manipulation). Altogether, our studies in mice demonstrate that sleep deprivation does not necessarily cause memory loss but instead leads to the suboptimal storage of information that cannot be retrieved without drug treatment or optogenetic stimulation. Furthermore, our findings suggest that object-location memories, consolidated under sleep deprivation conditions and thought to be lost, can be made accessible again several days after the learning and sleep deprivation episode, using the clinically approved PDE4 inhibitor roflumilast.

An integrated targeted metabolomics and network pharmacology approach to exploring the mechanism of ellagic acid against sleep deprivation-induced memory impairment and anxiety

Background

As a neuroprotective agent, ellagic acid (EA) is extremely beneficial. Our previous study found that EA can alleviate sleep deprivation (SD)-induced abnormal behaviors, although the mechanisms underlying this protective effect have not yet been fully elucidated.

Objective

An integrated network pharmacology and targeted metabolomics approach was utilized in this study to investigate the mechanism of EA against SD-induced memory impairment and anxiety.

Methods

Behavioral tests were conducted on mice after 72 h of SD. Hematoxylin and eosin staining and nissl staining were then carried out. Integration of network pharmacology and targeted metabolomics was performed. Eventually, the putative targets were further verified using molecular docking analyses and immunoblotting assays.

Results

The present study findings confirmed that EA ameliorated the behavioral abnormalities induced by SD and prevented histopathological and morphological damage to hippocampal neurons. Through multivariate analysis, clear clustering was obtained among different groups, and potential biomarkers were identified. Four key targets, catechol-O-methyltransferase (COMT), cytochrome P450 1B1 (CYP1B1), glutathione S-transferase A2 (GSTA2), and glutathione S-transferase P1 (GSTP1), as well as the related potential metabolites and metabolic pathways, were determined by further integrated analysis. Meanwhile, in-silico studies revealed that EA is well located inside the binding site of CYP1B1 and COMT. The experimental results further demonstrated that EA significantly reduced the increased expression of CYP1B1 and COMT caused by SD.

Conclusion

The findings of this study extended our understanding of the underlying mechanisms by which EA treats SD-induced memory impairment and anxiety, and suggested a novel approach to address the increased health risks associated with sleep loss.

Amide Proton Transfer-Weighted Imaging Detects Hippocampal Proteostasis Disturbance Induced by Sleep Deprivation at 7.0 T MRI

Sleep deprivation leads to hippocampal injury. Proteostasis disturbance is an important mechanism linking sleep deprivation and hippocampal injury. However, identifying noninvasive imaging biomarkers for hippocampal proteostasis disturbance remains challenging. Amide proton transfer-weighted (APTw) imaging is a chemical exchange saturation transfer technique based on the amide protons in proteins and peptides. We aimed to explore the ability of APTw imaging in detecting sleep deprivation-induced hippocampal proteostasis disturbance and its biological significance, as well as its biological basis. In vitro, the feasibility of APTw imaging in detecting changes of the protein state was evaluated, demonstrating that APTw imaging can detect alterations in the protein concentration, conformation, and aggregation state. In vivo, the hippocampal APTw signal declined with increased sleep deprivation time and was significantly lower in sleep-deprived rats than that in normal rats. This signal was positively correlated with the number of surviving neurons counted in Nissl staining and negatively correlated with the expression of glucose-regulated protein 78 evaluated in immunohistochemistry. Differentially expressed proteins in proteostasis network pathways were identified in the hippocampi of normal rats and sleep-deprived rats via mass spectrometry proteomics analysis, providing the biological basis for the change of the hippocampal APTw signal in sleep-deprived rats. These findings demonstrate that APTw imaging can detect hippocampal proteostasis disturbance induced by sleep deprivation and reflect the extent of neuronal injury and endoplasmic reticulum stress.

A short-term memory trace persists for days in the mouse hippocampus

Active recall of short-term memory (STM) is known to last for a few hours, but whether STM has long-term functions is unknown. Here we show that STM can be optogenetically retrieved at a time point during which natural recall is not possible, uncovering the long-term existence of an STM engram. Moreover, re-training within 3 days led to natural long-term recall, indicating facilitated consolidation. Inhibiting offline CA1 activity during non-rapid eye movement (NREM) sleep, N-methyl-D-aspartate receptor (NMDAR) activity, or protein synthesis after first exposure to the STM-forming event impaired the future re-exposure-facilitated consolidation, which highlights a role of protein synthesis, NMDAR and NREM sleep in the long-term storage of an STM trace. These results provide evidence that STM is not completely lost within hours and demonstrates a possible two-step STM consolidation, first long-term storage as a behaviorally inactive engram, then transformation into an active state by recurrence within 3 days.

Short-term memory (STM) forms a protein synthesis-, NMDAR- and NREM sleep-dependent engram which lasts at least 3 days in the mouse hippocampus following a novel object location task, suggesting that STM is not completely lost within hours.

Intestinal Microbiota and Sleep Inversion

Various human lifestyle and environmental factors are known to influence sleep. The number of adults and children suffering from chronic sleep disorders has grown over the past decade. Lack of sleep and impaired circadian rhythms have been proven to be associated with adverse metabolic health effects. Often, such disorders are associated with gastrointestinal tract diseases, and accompanied by dysbiosis. Significant number of studies have been conducted on animal models in recent years. They have shown the correlation between the gut microbiota and brain functions. According to these results scientists have clearly demonstrated the role of gut microbiota in regulating brain function, sleep, and behavior. The number of studies with volunteers is currently limited. The bacteria forming gut microbiota have significant impact on human health by synthesizing and secreting biologically active substances such as vitamins, essential amino acids, lipids, and others. Moreover, they have an indirect effect by modulating metabolic processes and the immune system. Changes in gut microbiota diversity occur due to the lack of sleep and shifting circadian rhythms, and it can lead to changes in the structure and function of microorganisms living in the gut. This can lead to changes in the composition and number of metabolites synthesized by these microorganisms (such as short-chain fatty acids and secondary bile acids) which contributes to the development of chronic inflammation, increased body weight and endocrine changes. This article provides the literature review on issues of interaction between gut microbiota and processes occurring during sleep.

An Adaptive Role for DNA Double-Strand Breaks in Hippocampus-Dependent Learning and Memory

DNA double-strand breaks (DSBs), classified as the most harmful type of DNA damage based on the complexity of repair, lead to apoptosis or tumorigenesis. In aging, DNA damage increases and DNA repair decreases. This is exacerbated in disease, as post-mortem tissue from patients diagnosed with mild cognitive impairment (MCI) or Alzheimer's disease (AD) show increased DSBs. A novel role for DSBs in immediate early gene (IEG) expression, learning, and memory has been suggested. Inducing neuronal activity leads to increases in DSBs and upregulation of IEGs, while increasing DSBs and inhibiting DSB repair impairs long-term memory and alters IEG expression. Consistent with this pattern, mice carrying dominant AD mutations have increased baseline DSBs, and impaired DSB repair is observed. These data suggest an adaptive role for DSBs in the central nervous system and dysregulation of DSBs and/or repair might drive age-related cognitive decline (ACD), MCI, and AD. In this review, we discuss the adaptive role of DSBs in hippocampus-dependent learning, memory, and IEG expression. We summarize IEGs, the history of DSBs, and DSBs in synaptic plasticity, aging, and AD. DSBs likely have adaptive functions in the brain, and even subtle alterations in their formation and repair could alter IEGs, learning, and memory.

Horizons in Human Aging Neuroscience: From Normal Neural Aging to Mental (Fr)Agility

While aging is an important risk factor for neurodegenerative disorders such as Alzheimer's disease and Parkinson's disease, age-related cognitive decline can also manifest without apparent neurodegenerative changes. In this review, we discuss molecular, cellular, and network changes that occur during normal aging in the absence of neurodegenerative disease. Emerging findings reveal that these changes include metabolic alterations, oxidative stress, DNA damage, inflammation, calcium dyshomeostasis, and several other hallmarks of age-related neural changes that do not act on their own, but are often interconnected and together may underlie age-related alterations in brain plasticity and cognitive function. Importantly, age-related cognitive decline may not be reduced to a single neurobiological cause, but should instead be considered in terms of a densely connected system that underlies age-related cognitive alterations. We speculate that a decline in one hallmark of neural aging may trigger a decline in other, otherwise thus far stable subsystems, thereby triggering a cascade that may at some point also incur a decline of cognitive functions and mental well-being. Beyond studying the effects of these factors in isolation, considerable insight may be gained by studying the larger picture that entails a representative collection of such factors and their interactions, ranging from molecules to neural networks. Finally, we discuss some potential interventions that may help to prevent these alterations, thereby reducing cognitive decline and mental fragility, and enhancing mental well-being, and healthy aging.

Sleep Disturbances, Changes in Sleep, and Cognitive Function in Low-Income African Americans

BACKGROUND

Sleep problems may contribute to the disproportionate burden of Alzheimer's disease and related dementias (ADRD) among African Americans (AAs).

OBJECTIVE

To examine the role of sleep problems in contributing to cognitive function and clinically adjudicated cognitive impairment in a predominantly AA sample.

METHODS

This study (n = 216, 78.8% female; mean age = 67.7 years) examined associations between 1) the level (i.e., measured in 2018) and 2) change over time (from 2013 to 2018; n = 168) in actigraphy-assessed sleep with domain-specific cognitive function and clinically adjudicated cognitive impairment (2018) in a community-dwelling, predominantly AA (96.9%) sample. A comprehensive cognitive battery assessed global cognitive function (3MS) and domain-specific cognitive function (attention, visuo-spatial ability, language, delayed recall, immediate recall, and executive function) in 2018. Sleep was measured in 2013 and 2018 via actigraphy.

RESULTS

Higher sleep efficiency and less wakefulness after sleep onset (WASO; measured in 2018) were associated with greater attention, executive function, and visuospatial ability. Increases in sleep efficiency between 2013 and 2018 were associated with better executive function, language, immediate recall, and visuospatial ability, whereas increases in WASO (2013-2018) were associated with poorer attention, executive function, and visuospatial ability. Level or change in sleep duration were not associated with domain-specific cognitive function, nor were any sleep measures associated with clinically adjudicated cognitive impairment.

CONCLUSION

In a predominantly AA sample of older adults, both the level and change (i.e., worsening) of sleep efficiency and WASO were associated with poorer cognitive function. Improving sleep health may support ADRD prevention and reduce health disparities.

Gender Differences in Hippocampal/Parahippocampal Functional Connectivity Network in Patients Diagnosed with Chronic Insomnia Disorder

BACKGROUND

Gender differences in hippocampal and parahippocampal gyrus (HIP/PHG) volumes have been reported in sleep disorders. Therefore, this study investigated the moderating effect of gender on the relationship between chronic insomnia disorder (CID) and the HIP/PHG functional connectivity (FC) network.

METHODS

For this study, 110 patients diagnosed with CID (43 men and 67 women) and 60 matched good sleep control (GSC) (22 men and 38 women) were recruited. These participants underwent resting-state functional magnetic resonance imaging scans, after which a 2 × 2 (diagnosis × gender) analysis of variance was used to detect the main and interactive effect of insomnia and gender on their HIP/PHG FC networks.

RESULTS

Although the main effect of insomnia on the HIP FC network was observed in the bilateral cerebellar tonsil, superior frontal gyrus, and the medial orbitofrontal cortex, effects on the PHG FC network were observed in the bilateral HIP and amygdala. In contrast, the main effect of gender on the HIP FC network was observed in the right cerebellum posterior lobe, the dorsolateral prefrontal cortex (DLPFC), and the supplemental motor area. Of note, the interactive effect of both insomnia and gender was observed in FCs between the right HIP and the dorsal anterior cingulate cortex, and then between the right PHG and DLPFC. Moreover, the FC between the right PHG and left DLPFC was positively associated with anxiety scores in the female patients with CID.

CONCLUSION

Our study identified that gender differences in brain connectivity existed between the HIP/PHG and executive control network in patients diagnosed with CID, these results will eventually extend our understanding of the important role that gender plays in the pathophysiology of CID.

Hippocampal neurons' cytosolic and membrane-bound ribosomal transcript profiles are differentially regulated by learning and subsequent sleep

Sleep loss disrupts consolidation of hippocampus-dependent memory. To understand the cellular basis for this effect, we quantified RNAs associated with translating ribosomes in cytosol and on cellular membranes of different hippocampal neuron populations. Our analysis suggests that while sleep loss (but not learning) alters numerous ribosomal transcripts in cytosol, learning has dramatic effects on transcript profiles for less–well-characterized membrane-bound ribosomes. We demonstrate that postlearning sleep deprivation occludes already minimal learning-driven changes on cytosolic ribosomes. It simultaneously alters transcripts associated with metabolic and biosynthetic processes in membrane-bound ribosomes in excitatory hippocampal neurons and highly active, putative “engram” neurons, respectively. Together, these findings provide insights into the cellular mechanisms altered by learning and their disruption by subsequent sleep loss.

The hippocampus is essential for consolidating transient experiences into long-lasting memories. Memory consolidation is facilitated by postlearning sleep, although the underlying cellular mechanisms are largely unknown. We took an unbiased approach to this question by using a mouse model of hippocampally mediated, sleep-dependent memory consolidation (contextual fear memory). Because synaptic plasticity is associated with changes to both neuronal cell membranes (e.g., receptors) and cytosol (e.g., cytoskeletal elements), we characterized how these cell compartments are affected by learning and subsequent sleep or sleep deprivation (SD). Translating ribosome affinity purification was used to profile ribosome-associated RNAs in different subcellular compartments (cytosol and membrane) and in different cell populations (whole hippocampus, Camk2a+ neurons, or highly active neurons with phosphorylated ribosomal subunit S6 [pS6+]). We examined how transcript profiles change as a function of sleep versus SD and prior learning (contextual fear conditioning; CFC). While sleep loss altered many cytosolic ribosomal transcripts, CFC altered almost none, and CFC-driven changes were occluded by subsequent SD. In striking contrast, SD altered few transcripts on membrane-bound (MB) ribosomes, while learning altered many more (including long non-coding RNAs [lncRNAs]). The cellular pathways most affected by CFC were involved in structural remodeling. Comparisons of post-CFC MB transcript profiles between sleeping and SD mice implicated changes in cellular metabolism in Camk2a+ neurons and protein synthesis in highly active pS6+ (putative “engram”) neurons as biological processes disrupted by SD. These findings provide insights into how learning affects hippocampal neurons and suggest that the effects of SD on memory consolidation are cell type and subcellular compartment specific.

The role of sleep disturbance and inflammation for spatial memory

Spatial memory is a brain function involved in multiple behaviors such as planning a route or recalling an object's location. The formation of spatial memory relies on the homeostasis of various biological systems, including healthy sleep and a well-functioning immune system. While sleep is thought to promote the stabilization and storage of spatial memories, considerable evidence shows that the immune system modulates neuronal processes underlying spatial memory such as hippocampal neuroplasticity, long-term potentiation, and neurogenesis. Conversely, when sleep is disturbed and/or states of heightened immune activation occur, hippocampal regulatory pathways are altered, which - on a behavioral level - may result in spatial memory impairments. In this Brief Review, I summarize how sleep and the immune system contribute to spatial memory processes. In addition, I present emerging evidence suggesting that sleep disturbance and inflammation might jointly impair spatial memory. Finally, potentials of integrated strategies that target sleep disturbance and inflammation to possibly mitigate risk for spatial memory impairment are discussed.

Altered hippocampal transcriptome dynamics following sleep deprivation

Widespread sleep deprivation is a continuing public health problem in the United States and worldwide affecting adolescents and adults. Acute sleep deprivation results in decrements in spatial memory and cognitive impairments. The hippocampus is vulnerable to acute sleep deprivation with changes in gene expression, cell signaling, and protein synthesis. Sleep deprivation also has long lasting effects on memory and performance that persist after recovery sleep, as seen in behavioral studies from invertebrates to humans. Although previous research has shown that acute sleep deprivation impacts gene expression, the extent to which sleep deprivation affects gene regulation remains unknown. Using an unbiased deep RNA sequencing approach, we investigated the effects of acute sleep deprivation on gene expression in the hippocampus. We identified 1,146 genes that were significantly dysregulated following sleep deprivation with 507 genes upregulated and 639 genes downregulated, including protein coding genes and long non-coding RNAs not previously identified as impacted by sleep deprivation. Notably, genes significantly upregulated after sleep deprivation were associated with RNA splicing and the nucleus. In contrast, downregulated genes were associated with cell adhesion, dendritic localization, the synapse, and postsynaptic membrane. Furthermore, we found through independent experiments analyzing a subset of genes that three hours of recovery sleep following acute sleep deprivation was sufficient to normalize mRNA abundance for most genes, although exceptions occurred for some genes that may affect RNA splicing or transcription. These results clearly demonstrate that sleep deprivation differentially regulates gene expression on multiple transcriptomic levels to impact hippocampal function.

Sleep loss drives acetylcholine- and somatostatin interneuron-mediated gating of hippocampal activity to inhibit memory consolidation

Sleep loss disrupts consolidation of hippocampus-dependent memory. To characterize effects of learning and sleep loss, we quantified activity-dependent phosphorylation of ribosomal protein S6 (pS6) across the dorsal hippocampus of mice. We find that pS6 is enhanced in dentate gyrus (DG) following single-trial contextual fear conditioning (CFC) but is reduced throughout the hippocampus after brief sleep deprivation (SD; which disrupts contextual fear memory [CFM] consolidation). To characterize neuronal populations affected by SD, we used translating ribosome affinity purification sequencing to identify cell type-specific transcripts on pS6 ribosomes (pS6-TRAP). Cell type-specific enrichment analysis revealed that SD selectively activated hippocampal somatostatin-expressing (Sst+) interneurons and cholinergic and orexinergic hippocampal inputs. To understand the functional consequences of SD-elevated Sst+ interneuron activity, we used pharmacogenetics to activate or inhibit hippocampal Sst+ interneurons or cholinergic input from the medial septum. The activation of either cell population was sufficient to disrupt sleep-dependent CFM consolidation by gating activity in granule cells. The inhibition of either cell population during sleep promoted CFM consolidation and increased S6 phosphorylation among DG granule cells, suggesting their disinhibition by these manipulations. The inhibition of either population across post-CFC SD was insufficient to fully rescue CFM deficits, suggesting that additional features of sleeping brain activity are required for consolidation. Together, our data suggest that state-dependent gating of DG activity may be mediated by cholinergic input and local Sst+ interneurons. This mechanism could act as a sleep loss-driven inhibitory gate on hippocampal information processing.

Sleep Loss Drives Brain Region-Specific and Cell Type-Specific Alterations in Ribosome-Associated Transcripts Involved in Synaptic Plasticity and Cellular Timekeeping

Sleep and sleep loss are thought to impact synaptic plasticity, and recent studies have shown that sleep and sleep deprivation (SD) differentially affect gene transcription and protein translation in the mammalian forebrain. However, much less is known regarding how sleep and SD affect these processes in different microcircuit elements within the hippocampus and neocortex, for example, in inhibitory versus excitatory neurons. Here, we use translating ribosome affinity purification (TRAP) and in situ hybridization to characterize the effects of sleep versus SD on abundance of ribosome-associated transcripts in Camk2a-expressing (Camk2a+) pyramidal neurons and parvalbumin-expressing (PV+) interneurons in the hippocampus and neocortex of male mice. We find that while both Camk2a+ neurons and PV+ interneurons in neocortex show concurrent SD-driven increases in ribosome-associated transcripts for activity-regulated effectors of plasticity and transcriptional regulation, these transcripts are minimally affected by SD in hippocampus. Similarly, we find that while SD alters several ribosome-associated transcripts involved in cellular timekeeping in neocortical Camk2a+ and PV+ neurons, effects on circadian clock transcripts in hippocampus are minimal, and restricted to Camk2a+ neurons. Taken together, our results indicate that SD effects on transcripts associated with translating ribosomes are both cell type-specific and brain region-specific, and that these effects are substantially more pronounced in the neocortex than the hippocampus. We conclude that SD-driven alterations in the strength of synapses, excitatory-inhibitory (E-I) balance, and cellular timekeeping are likely more heterogeneous than previously appreciated.SIGNIFICANCE STATEMENT Sleep loss-driven changes in transcript and protein abundance have been used as a means to better understand the function of sleep for the brain. Here, we use translating ribosome affinity purification (TRAP) to characterize changes in abundance of ribosome-associated transcripts in excitatory and inhibitory neurons in mouse hippocampus and neocortex after a brief period of sleep or sleep loss. We show that these changes are not uniform, but are generally more pronounced in excitatory neurons than inhibitory neurons, and more pronounced in neocortex than in hippocampus.

Inconsistent effects of sleep deprivation on memory function

In this review article, we aimed to discuss the role of sleep deprivation (SD) in learning and memory processing in basic and clinical studies. There are numerous studies investigating the effect of SD on memory, while most of these studies have shown the impairment effect of SD. However, some of these studies have reported conflicting results, indicating that SD does not impair memory performance or even improves it. So far, no study has discussed or compared the conflicting results of SD on learning and memory. Thus, this important issue in the neuroscience of sleep remains unknown. The main goal of this review article is to compare the similar mechanisms between the impairment and the improvement effects of SD on learning and memory, probably leading to a scientific solution that justifies these conflicting results. We focused on the inconsistent effects of SD on some mechanisms involved in learning and memory, and tried to discuss the inconsistent effects of SD on learning and memory.

Critical Effects on Akt Signaling in Adult Zebrafish Brain Following Alterations in Light Exposure

Evidence from human and animal studies indicate that disrupted light cycles leads to alterations of the sleep state, poor cognition, and the risk of developing neuroinflammatory and generalized health disorders. Zebrafish exhibit a diurnal circadian rhythm and are an increasingly popular model in studies of neurophysiology and neuropathophysiology. Here, we investigate the effect of alterations in light cycle on the adult zebrafish brain: we measured the effect of altered, unpredictable light exposure in adult zebrafish telencephalon, homologous to mammalian hippocampus, and the optic tectum, a significant visual processing center with extensive telencephalon connections. The expression of heat shock protein-70 (HSP70), an important cell stress mediator, was significantly decreased in optic tectum of adult zebrafish brain following four days of altered light exposure. Further, pSer473-Akt (protein kinase B) was significantly reduced in telencephalon following light cycle alteration, and pSer9-GSK3β (glycogen synthase kinase-3β) was significantly reduced in both the telencephalon and optic tectum of light-altered fish. Animals exposed to five minutes of environmental enrichment showed significant increase in pSer473Akt, which was significantly attenuated by four days of altered light exposure. These data show for the first time that unpredictable light exposure alters HSP70 expression and dysregulates Akt-GSK3β signaling in the adult zebrafish brain.

The role of microRNAs in learning and long-term memory

The mechanisms of long-term memory formation and ways to improve it (in the case of its impairment) remain an extremely difficult problem yet to be solved. Over the recent years, much attention has been paid to microRNAs in this regard. MicroRNAs are unique endogenous non-coding RNAs about 22 nucleotides in length; each can regulate translation of hundreds of messenger RNA targets, thereby controlling entire gene networks. MicroRNAs are widely represented in the central nervous system. A large number of studies are currently being conducted to investigate the role of microRNAs in the brain functioning. A number of microRNAs have been shown to be involved in the process of synaptic plasticity, as well as in the long-term memory formation. Disruption of microRNA biogenesis leads to significant cognitive dysfunctions. Moreover, impaired microRNA biogenesis is one of the causes of the pathogenesis of mental disorders, neurodegenerative illnesses and senile dementia, which are often accompanied by deterioration in the learning ability and by memory impairment. Optimistic predictions are made that microRNAs can be used as targets for therapeutic treatment and for diagnosing the above pathologies. The importance of applications related to microRNAs significantly raises interest in studying their functions in the brain. Thus, this review is focused on the role of microRNAs in cognitive processes. It describes microRNA biogenesis and the role of miRNAs in the regulation of gene expression, as well as the latest achievements in studying the functional role of microRNAs in learning and in long-term memory formation, depending on the activation or inhibition of their expression. The review presents summarized data on the effect of impaired microRNA biogenesis on long-term memory formation, including those associated with sleep deprivation. In addition, analysis is provided of the current literature related to the prospects of improving cognitive processes by influencing microRNA biogenesis via the use of CRISPR/Cas9 technologies and active mental and physical exercises.

A brief period of sleep deprivation leads to subtle changes in mouse gut microbiota

Not getting enough sleep is a common problem in our society and contributes to numerous health problems, including high blood pressure, diabetes and obesity. Related to these observations, a wealth of studies has underscored the negative impact of both acute and chronic sleep deprivation on cognitive function. More recently it has become apparent that the gut microbiota composition can be rapidly altered, modulates brain function and is affected by the aforementioned health problems. As such, changes in the microbiota composition may contribute to the behavioural and physiological phenotypes associated with sleep deprivation. It is unclear, however, whether a brief period of sleep deprivation can also negatively impact the gut microbiota. Here, we examined the impact of 5 hr of sleep deprivation on gut microbiota composition of male C57Bl6/J mice. Despite the fact that the overall microbial composition did not change between the control- and sleep-deprived groups, the relative abundance of the Clostridiaceae and Lachnospiraceae were slightly altered in sleep-deprived animals compared to controls. Together, these data suggest that depriving mice of sleep for 5 hr leads to subtle changes in the gut microbiota composition.