Differential effects of paradoxical sleep deprivation on memory and oxidative stress

The effect of REM-sleep disruption on affective processing: A systematic review of human and animal experimental studies

Evidence on the importance of rapid-eye-movement sleep (REMS) in processing emotions is accumulating. The focus of this systematic review is the outcomes of experimental REMS deprivation (REMSD), which is the most common method in animal models and human studies on REMSD. This review revealed that variations in the applied REMSD methods were substantial. Animal models used longer deprivation protocols compared with studies in humans, which mostly reported acute deprivation effects after one night. Studies on animal models showed that REMSD causes aggressive behavior, increased pain sensitivity, reduced sexual behavior, and compromised consolidation of fear memories. Animal models also revealed that REMSD during critical developmental periods elicits lasting consequences on affective-related behavior. The few human studies revealed increases in pain sensitivity and suggest stronger consolidation of emotional memories after REMSD. As pharmacological interventions (such as selective serotonin reuptake inhibitors [SSRIs]) may suppress REMS for long periods, there is a clear gap in knowledge regarding the effects and mechanisms of chronic REMS suppression in humans.

Transcranial Irradiation Mitigates Paradoxical Sleep Deprivation Effect in an Age-Dependent Manner: Role of BDNF and GLP-1

The growing prevalence of aged sleep-deprived nations is turning into a pandemic state. Acute sleep deprivation (SD) accompanies aging, changing the hippocampal cellular pattern, neurogenesis pathway expression, and aggravating cognitive deterioration. The present study investigated the ability of Near Infra Red (NIR) light laser to ameliorate cognitive impairment induced by SD in young and senile rats. Wistar rats ≤ 2 months (young) and ≥ 14 months (senile) were sleep-deprived for 72 h with or without transcranial administration of NIR laser of 830 nm. Our results showed that NIR photobiomodulation (PBM) attenuated cognitive deterioration made by SD in young, but not senile rats, while both sleep-deprived young and senile rats exhibited decreased anxiety (mania)-like behavior in response to PBM. NIR PBM had an inhibitory effect on AChE, enhanced the production of ACh, attenuated ROS, and regulated cell apoptosis factors such as Bax and Bcl-2. NIR increased mRNA expression of BDNF and GLP-1 in senile rats, thus facilitating neuronal survival and differentiation. The present findings also revealed that age exerts an additive factor to the cellular assaults produced by SD where hippocampal damages made in 2-month rats were less severe than those of the aged one. In conclusion, NIR PBM seems to promote cellular longevity of senile hippocampal cells by combating ROS, elevating neurotrophic factors, thus improving cognitive performance. The present findings provide NIR as a possible candidate for hippocampal neuronal insults accompanying aging and SD.

Impaired Mitochondrial Respiration in REM-Sleep Behavior Disorder: A Biomarker of Parkinson's Disease?

BACKGROUND

Idiopathic rapid eye movement (REM) sleep behavior disorder (iRBD) is associated with prodromal Parkinson's disease (PD), but the mechanisms linking phenoconversion of iRBD to PD have not yet been clarified. Considering the association between mitochondrial dysfunction and sleep disturbances in PD, we explored mitochondrial activity in fibroblasts derived from iRBD patients to identify a biochemical profile that could mark the presence of impending neurodegeneration.

METHODS

The study involved 28 participants, divided into three groups: patients diagnosed with iRBD, PD patients converted from iRBD (RBD-PD), and healthy controls. We performed a comprehensive assessment of mitochondrial function, including an examination of mitochondrial morphology, analysis of mitochondrial protein expression levels by western blot, and measurement of mitochondrial respiration using the Seahorse XFe24 analyzer.

RESULTS

In basal conditions, mitochondrial respiration did not differ between iRBD and control fibroblasts, but when cells were challenged with a higher energy demand, iRBD fibroblasts exhibited a significant (P = 0.006) drop in maximal and spare respiration compared to controls. Interestingly, RBD-PD patients showed the same alterations with a further significant reduction in oxygen consumption linked to adenosine triphosphate production (P = 0.032). Moreover, RBD-PD patients exhibited a significant decrease in protein levels of complexes III (P = 0.02) and V (P = 0.002) compared to controls, along with fragmentation of the mitochondrial network. iRBD patients showed similar, but milder alterations.

CONCLUSIONS

Altogether, these findings suggest that mitochondrial dysfunctions in individuals with iRBD might predispose to worsening of the bioenergetic profile observed in RBD-PD patients, highlighting these alterations as potential predictors of phenoconversion to PD. © 2023 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

Understanding the molecular mechanism of arsenic and ammonia toxicity and high-temperature stress in Pangasianodon hypophthalmus

The current investigation explores the mechanisms of ammonia and arsenic toxicity, along with high-temperature stress, which other researchers rarely addressed. Pangasianodon hypophthalmus was exposed to low doses of ammonia and arsenic (1/10th of LC50, 2.0 and 2.68 mg L-1, respectively) and high temperature (34 °C) for 105 days. The following treatments were applied: control (unexposed), arsenic (As), ammonia (NH3), ammonia + arsenic (NH3 + As), ammonia + temperature (NH3 + T), and NH3 + As + T. Cortisol levels significantly increased with exposure to ammonia (NH3), arsenic (As), and high temperature (34 °C) compared to the unexposed group. Heat shock protein (HSP 70), inducible nitric oxide synthase (iNOS), and metallothionein (MT) gene expressions were notably upregulated by 122-210%, 98-122%, and 64-238%, respectively, compared to the control. Neurotransmitter enzymes (acetylcholine esterase, AChE) were significantly inhibited by NH3 + As + T, followed by other stressor groups. The apoptotic (caspase, Cas 3a and 3b) and detoxifying (cytochrome P450, CYP P450) pathways were substantially affected by the NH3 + As + T group. Immune (total immunoglobulin, Ig; tumor necrosis factor TNFα; and interleukin IL) and growth-related genes (growth hormone, GH; growth hormone regulator, GHR1 and GHRβ; myostatin, MYST and somatostatin, SMT) were noticeably upregulated by NH3 + As + T, followed by other stress groups, compared to the control group. Weight gain %, protein efficiency ratio, feed efficiency ratio, specific growth rate, and other growth attributes were significantly affected by low doses of ammonia, arsenic, and high-temperature stress. Albumin, total protein, globulin, A:G ratio, and myeloperoxidase (MPO) were highly affected by the As + NH3 + T group. Blood profiling, including red blood cells (RBC), white blood count (WBC), and hemoglobin (Hb), were also impacted by stressor groups compared to the control group. Genotoxicity, as DNA damage, was significantly higher in groups exposed to NH3 + As + T (89%), NH3 + T (78%), NH3 (73), NH3 + As (71), and As (68%). The bioaccumulation of arsenic was substantially higher in liver and kidney tissues. The present study contributes to understanding the toxicity mechanisms of ammonia and arsenic, as well as high-temperature stress, through different gene expressions, biochemical attributes, genotoxicity, immunological status, and growth performance of P. hypophthalmus.

REM sleep deprivation induced by the modified multi-platform method has detrimental effects on memory: A systematic review and meta-analysis

The modified multi-platform method (MMPM) is used to induce animal models of paradoxical sleep deprivation and impairs memory in rodents. However, variations in MMPM protocols have contributed to inconsistent conclusions across studies. This meta-analysis aimed to assess the variations of the MMPM and their effects on memory in rats and mice. A comprehensive search identified 60 studies, and 50 were included in our meta-analysis. Overall, the meta-analysis showed that the MMPM significantly reduced the percentage of time spent in target quadrants (I2 = 54 %, 95 % confidence interval [CI] = [-1.83, -1.18]) and the number of platform-area crossings (I2 = 26 %, 95 % CI = [-1.71, -1.07]) in the Morris water maze (MWM) and shortened the latency to entering the dark compartment in the passive avoidance task (I2 = 68 %, 95 % CI = [-1.36, -0.57]), but it increased the number of errors in the radial arm water maze (RAWM) (I2 = 59 %, 95 % CI = [1.29, 2.07]). Additionally, mice performed worse on the MWM, whereas rats performed worse on the passive avoidance task. More significant memory deficits were found in cross-learning and post-learning MMPM in the MWM and RAWM, respectively. This study provided evidence that the MMPM can be used in preclinical studies of memory deficits induced by paradoxical sleep deprivation.

Mitochondrial control of sleep

The function of sleep remains one of biology's biggest mysteries. A solution to this problem is likely to come from a better understanding of sleep homeostasis, and in particular of the cellular and molecular processes that sense sleep need and settle sleep debt. Here, we highlight recent work in the fruit fly showing that changes in the mitochondrial redox state of sleep-promoting neurons lie at the heart of a homeostatic sleep-regulatory mechanism. Since the function of homeostatically controlled behaviours is often linked to the regulated variable itself, these findings corroborate with the hypothesis that sleep serves a metabolic function.

Proteostasis failure exacerbates neuronal circuit dysfunction and sleep impairments in Alzheimer's disease

Failed proteostasis is a well-documented feature of Alzheimer's disease, particularly, reduced protein degradation and clearance. However, the contribution of failed proteostasis to neuronal circuit dysfunction is an emerging concept in neurodegenerative research and will prove critical in understanding cognitive decline. Our objective is to convey Alzheimer's disease progression with the growing evidence for a bidirectional relationship of sleep disruption and proteostasis failure. Proteostasis dysfunction and tauopathy in Alzheimer's disease disrupts neurons that regulate the sleep-wake cycle, which presents behavior as impaired slow wave and rapid eye movement sleep patterns. Subsequent sleep loss further impairs protein clearance. Sleep loss is a defined feature seen early in many neurodegenerative disorders and contributes to memory impairments in Alzheimer's disease. Canonical pathological hallmarks, β-amyloid, and tau, directly disrupt sleep, and neurodegeneration of locus coeruleus, hippocampal and hypothalamic neurons from tau proteinopathy causes disruption of the neuronal circuitry of sleep. Acting in a positive-feedback-loop, sleep loss and circadian rhythm disruption then increase spread of β-amyloid and tau, through impairments of proteasome, autophagy, unfolded protein response and glymphatic clearance. This phenomenon extends beyond β-amyloid and tau, with interactions of sleep impairment with the homeostasis of TDP-43, α-synuclein, FUS, and huntingtin proteins, implicating sleep loss as an important consideration in an array of neurodegenerative diseases and in cases of mixed neuropathology. Critically, the dynamics of this interaction in the neurodegenerative environment are not fully elucidated and are deserving of further discussion and research. Finally, we propose sleep-enhancing therapeutics as potential interventions for promoting healthy proteostasis, including β-amyloid and tau clearance, mechanistically linking these processes. With further clinical and preclinical research, we propose this dynamic interaction as a diagnostic and therapeutic framework, informing precise single- and combinatorial-treatments for Alzheimer's disease and other brain disorders.

Administration of growth hormone ameliorates adverse effects of total sleep deprivation

Total sleep deprivation (TSD) causes several harmful changes including anxiety, inflammation, and increased expression of extracellular signal-regulated kinase (ERK) and tropomyosin receptor kinase B (TrkB) genes in the hippocampus. The current study was conducted to explain the possible effects of exogenous GH against the above parameters caused by TSD and the possible mechanisms involved. Male Wistar rats were divided into 1) control, 2) TSD and 3) TSD + GH groups. To induce TSD, the rats received a mild repetitive electric shock (2 mA, 3 s) to their paws every 10 min for 21 days. Rats in the third group received GH (1 ml/kg, sc) for 21 days as treatment for TSD. The motor coordination, locomotion, the level of IL-6, and expression of ERK and TrkB genes in hippocampal tissue were measured after TSD. The motor coordination (p < 0.001) and locomotion indices (p < 0.001) were impaired significantly by TSD. The concentrations of serum corticotropin-releasing hormone (CRH) (p < 0.001) and hippocampal interleukin-6 (IL-6) (p < 0.001) increased. However, there was a significant decrease in the interleukin-4 (IL-4) concentration and expression of ERK (p < 0.001) and TrkB (p < 0.001) genes in the hippocampus of rats with TSD. Treatment of TSD rats with GH improved motor balance (p < 0.001) and locomotion (p < 0.001), decreased serum CRH (p < 0.001), IL-6 (p < 0.01) but increased the IL-4 and expression of ERK (p < 0.001) and TrkB (p < 0.001) genes in the hippocampus. Results show that GH plays a key role in modulating the stress hormone, inflammation, and the expression of ERK and TrkB genes in the hippocampus following stress during TSD.

Consequences of post-weaning sleep deprivation on behaviour and oxidative stress parameters in rat plasma and brain

Sleep is essential for health: Adequate sleep is essential for healthy development and sleep deprivation results in several consequences. Indeed, sleep deprivation early in life is associated with poor behaviour and cognition, as well as impaired mental and physical health. Preclinical studies have shown that sleep deprivation alters several physiological functions later in life such as the cardiovascular, immune and endocrine systems, resulting in altered oxidative states. Most of the preclinical literature is focused on adult animals, and little is known about oxidative alterations during development, especially in the context of sleep deprivation. Hence, we adapted a classic and well-documented model of sleep deprivation, paradoxical sleep deprivation using multiple platforms, for juvenile rats and explored central and peripheral oxidative parameters, as well as the behavioural consequences of sleep deprivation post-weaning. We showed that 96 h of paradoxical sleep deprivation induced a significant reduction in body weight, decreased sucrose preference-a behaviour suggestive of anhedonia-and increased glucose and decreased cholesterol in the plasma. In the brain, we observed a decrease in reduced glutathione levels in the medial prefrontal cortex and an increase in thiobarbituric acid reactive substance levels in the hypothalamus, indicating oxidative damage in these regions. Taken together, our findings suggest that paradoxical sleep deprivation during development induces anhedonic behaviour and promotes central and peripheral alterations in oxidative parameters.

Attenuation Effect of Recovery Sleep for Impaired Reproductive Function in Male Rats by Sleep Deprivation

PURPOSE

The aim of the present study was to test the hypothesis that recovery sleep could counteract the detrimental effects of sleep deprivation (SD) on male rats' fertility.

MATERIALS AND METHODS

Twenty-two rats were housed in groups of six per cage with unrestricted access to food and water in a room. The modified multiple platform method was used to induce SD in rats over a 96-hour period. We examined the effect of SD on semen quality, reproductive hormones, and testicular histology in adult male rats. Then, we investigated the effect of 7 days recovery sleep on impaired reproductive function induced by SD.

RESULTS

After the acclimation period, 22 rats were randomly separated into three experimental groups (SD, recovery sleep, and the control groups). Ninety-six hours of SD resulted in a significant decrease in sperm motility (24.33±10.93 vs. 48.20±8.55, p<0.001) and the number of morphologically normal sperm (9.68±2.77 vs. 26.21±14.60, p<0.01) in rats, accompanied by a decrease in testosterone levels (1.53±0.55 vs. 4.44±0.56, p<0.001) and destruction of testicular tissue structure compared with control group. After 7 days of recovery sleep, semen quality, especially sperm motility, was improved and testosterone levels were significantly higher compared to post-SD (3.70±0.53 vs. 1.53±0.55, p<0.05), but remained low compared to the control group.

CONCLUSIONS

In conclusion, 96 hours of SD deteriorated the parameters of sperm motility and the number of morphologically normal sperm in rats, probably due to the decrease in serum testosterone levels and the disruption of testicular tissue structure when compared to the control group. After 7 days of recovery sleep, semen parameter, especially sperm motility and testosterone levels did not return to baseline levels compared to the control group.

Dynamic hippocampal functional connectivity responses to varying working memory loads following total sleep deprivation

Sleep loss with work overload can impact human cognitive performance. However, the brain's response to an increased working memory load following total sleep deprivation (TSD) remains unclear. In the present study, we focussed on the dynamic response of the hippocampus to increased working memory load before and after total sleep deprivation of 36 h. A total of 16 male participants completed a verbal working memory task under functional magnetic resonance imaging. After whole-brain activation analysis and region of interest analysis of the hippocampus, the generalised form of context-dependent psychophysiological interactions (gPPI) was used to analyse the hippocampal functional connectivity with the whole brain. The results revealed that as the working memory load increased within a small range, from 0-back to 1-back task, the left hippocampal functional connectivity decreased with the left supplementary motor area, left pars opercularis, left rolandic operculum, right superior frontal gyrus, bilateral precentral gyrus, and left middle cingulate cortex following total sleep deprivation compared with that observed in resting wakefulness. When the working memory load further increased from 1-back to 2-back task, the connectivity increased between the left hippocampus and the left superior parietal lobule as well as between the left hippocampus and right lingual gyrus after total sleep deprivation compared with that observed in resting wakefulness. Moreover, the left hippocampus gPPI effect on the left middle cingulate cortex and left superior parietal lobule could predict the behavioural test accuracy in 1-back and 2-back task, respectively, following total sleep deprivation. These findings indicated that increased working memory load after total sleep deprivation disrupts working memory processes. The brain reacts to these disruptions in a dynamic and flexible manner, involving not only brain activation but also hippocampus-related functional network connections.

A review on pathophysiological aspects of Sleep Deprivation

Sleep deprivation (SD) (also referred as insomnia) is a condition in which peoples fails to get enough sleep due to excessive yawning, facing difficulty to learn new concepts, forgetfulness as well as depressed mood. This could be occurs due to several possible reasons including medications, stress (caused by shift work). Despite the fact that sleep is important for the normal physiology, it currently affects millions of people around the world US (70 million) and Europe (45 million). Due to increase work demand nowadays lots of peoples experiencing sleep deprivation hence, this could be the reason for several car accident followed by death and morbidity. This review highlighted the impact of SD on neurotransmitter release and functions, theories (Flip-flop theory, oxidative stress theory, neuroinflammation theory, neurotransmitter theory, and hormonal theory) associated with SD pathogenesis apart from this it also demonstrate the molecular pathways underlying SD (PI3K and Akt , NF-κB, Nrf2, and adenosine pathway. However, this study also elaborates the SD induced changes in the level of neurotransmitters, hormonal, and mitochondrial functions. Along with this, it also covers several molecular aspects associated with SD as well. Through this study a link is made between SD and associated causes, which will further help to develop potential therapeutic strategy against SD.

Evaluating the effect of selenium on spatial memory impairment induced by sleep deprivation

Sleep deprivation (SD) impairs memory due to disturbing oxidative stress parameters. Selenium is a main component of several antioxidant enzymes and provides a neuroprotective effect. The present study aimed to investigate the potential neuroprotective effect of chronic selenium administration on cognitive impairments induced by chronic SD. Adult male Wister rats were randomly assigned into five groups (n = 12/group). The SD was induced in rats using modified multiple platform model. Selenium (6 µg/kg of animal's body weight) was administered to rats via oral gavage for 6 weeks. The spatial learning and memory were assessed using the radial arm water maze (RAWM). Moreover, we measured the levels of reduced glutathione (GSH), oxidized glutathione (GSSG) and GSH/GSSG, catalase, glutathione peroxidase (GPx), superoxide dismutase (SOD), thiobarbituric acid reactive substances (TBARS) and brain derived neurotrophic factor (BDNF) in the hippocampus. The results indicate that short- and long-term memory were impaired by chronic sleep deprivation (P < 0.05), while selenium administration prevented this effect. Moreover, selenium normalized antioxidants activities which were reduced by SD such as: catalase (P < 0.05), and SOD (P < 0.05), and significantly enhanced the ratio of GSH/GSSG in sleep-deprived rats (P < 0.05), without significant alteration of BDNF (P > 0.05), GSH (P > 0.05), or TBARS levels (P > 0.05). In conclusion, chronic SD induced memory impairment, and chronic treatment with selenium prevented this impairment by normalizing antioxidant enzymes activities in the hippocampus.

Sleep Characteristics and Cognitive Function in Older Adults Without Dementia: The CABLE Study

BACKGROUND

The associations between sleep characteristics and cognition are complicated. Alzheimer's disease (AD) pathologies have been proven to be associated with sleep characteristics.

OBJECTIVE

We aimed to investigate the associations between sleep characteristics and cognitive function and examine the roles of AD pathologies in modulating the association of sleep duration with cognition.

METHODS

A total of 974 participants who had measurements of cerebrospinal fluid (CSF) amyloid-β (Aβ), phosphorylated tau (P-tau), total tau proteins (T-tau), cognitive function, and sleep characteristics were included from the Chinese Alzheimer's Biomarker and Lifestyle (CABLE) study. Linear regression analyses were utilized to explore the associations of sleep characteristics with cognition. Non-linear regression analyses were utilized to explore the associations of sleep habits with cognition. Causal mediation analyses were conducted to explore the mediation effects of AD pathologies on cognition.

RESULTS

The Pittsburgh Sleep Quality Index (PSQI) total score was significantly negatively correlated with Montreal Cognitive Assessment (MoCA) score (p = 0.0176). Long latency (p = 0.0054) and low efficiency (p = 0.0273) were associated with cognitive impairment. Habitual nap behavior was associated with lower MoCA scores (p = 0.0045). U-shaped associations were observed between sleep habits (bedtime and nocturnal sleep duration) and cognition. A causal mediation analysis indicated that P-tau/Aβ42 mediated the association of sleep duration with cognition.

CONCLUSION

These findings showed sleep characteristics were associated with cognitive functions. Sleep habits (duration, bedtime) had U-shaped associations with cognition. AD core pathologies might partially mediate the influence of sleep duration on cognitive impairments.

Effects of tamoxifen and glutamate and glutamine levels in brain regions in repeated sleep deprivation-induced mania model in mice

Protein kinase C inhibitor tamoxifen reduces symptoms of acute mania in bipolar patients and mania-like behaviors in animals. Memory impairment and altered levels of glutamate and glutamate/glutamine ratio have been reported in mania. Tamoxifen suppresses glutamate release which plays an important role in memory. The present study evaluated whether tamoxifen's activity participates in its antimanic efficacy in repeated sleep deprivation mania model. Mice were divided into control and 24-h sleep-deprived groups and were treated with vehicle or 1 mg/kg tamoxifen twice daily for 8 days. Sleep deprivation was repeated three times at intervals of 2 days. Square crossing and rearing were recorded as measures of locomotor activity. Memory and risk taking behavior were evaluated using novel object recognition and staircase tests, respectively. Glutamate and glutamine levels were measured in the frontal cortex and hippocampus. Behavioral tests were conducted 24 h after the second or immediately after the third sleep deprivations. Sleep deprivation increased locomotor activity and risk taking. Glutamate and glutamine levels and glutamate/glutamine ratio in the frontal cortex and hippocampus were unaffected. Locomotor hyperactivity was prevented by tamoxifen treatment. No change in the recognition index suggested lack of memory impairment in the model. These findings confirm the relevance of repeated sleep deprivation as a mania model and tamoxifen as an antimanic agent. However, future research is needed to further address lack of memory impairment in the model and lack of glutamatergic influence on the model and antimanic effect of tamoxifen.

Sleep deprivation induces oxidative stress in the liver and pancreas in young and aging rats

The aging process is characterized by a gradual impairment generally caused by oxidative stress and, more specifically, sleep deprivation, which induces oxidative stress in the brain. The objective of this study was to assess the effect of three types of paradoxical sleep deprivation (PSD): 96 h of PSD (96PSD group); 192 h of PSD (192PSD group); 192 h of PSD followed by a recovery period of 20 days (192PSD + Recovery group) on an oral glucose tolerance test (OGTT), lipid peroxidation (LPO), and superoxide dismutase (SOD) and catalase (CAT) activities in the liver and pancreas of young (3-month-old) and adult (14-month-old) rats. The 96PSD and 192PSD groups of young rats showed lower glucose levels on the OGTT than the control group. In the adult rats, only the 96PSD group had lower glucose levels than the control group. However, the areas under the curve for the young and adult 192 and 192PSD + Recovery groups showed significant differences. Both LPO and SOD increased in the 192PSD and 192PSD + Recovery groups, but CAT decreased in the liver of young rats in the 192PSD group. Regarding the pancreas, LPO and SOD levels increased after 96 h of PSD. In adult animals, CAT decreased in the liver after 96 and 192 h of PSD, while LPO and SOD increased in the pancreas of the 192PSD and PSD + Recovery groups. Differences in the SOD and CAT activities in the liver and SOD activities in the pancreas were also observed between the young and adult rats and maintained across all the PSD groups. In conclusion, PSD induced differential responses that appeared to depend on the duration of the induced condition, the animals’ age, and the tissue analyzed. It was found that adult rats were more susceptible to the effects of PSD than young rats.

Molecular Mechanisms Underlying Reciprocal Interactions Between Sleep Disorders and Parkinson's Disease

Sleep-wake disruptions are among the most prevalent and burdensome non-motor symptoms of Parkinson's disease (PD). Clinical studies have demonstrated that these disturbances can precede the onset of typical motor symptoms by years, indicating that they may play a primary function in the pathogenesis of PD. Animal studies suggest that sleep facilitates the removal of metabolic wastes through the glymphatic system via convective flow from the periarterial space to the perivenous space, upregulates antioxidative defenses, and promotes the maintenance of neuronal protein homeostasis. Therefore, disruptions to the sleep-wake cycle have been associated with inefficient metabolic clearance and increased oxidative stress in the central nervous system (CNS). This leads to excessive accumulation of alpha-synuclein and the induction of neuronal loss, both of which have been proposed to be contributing factors to the pathogenesis and progression of PD. Additionally, recent studies have suggested that PD-related pathophysiological alterations during the prodromal phase disrupt sleep and circadian rhythms. Taken together, these findings indicate potential mechanistic interactions between sleep-wake disorders and PD progression as proposed in this review. Further research into the hypothetical mechanisms underlying these interactions would be valuable, as positive findings may provide promising insights into novel therapeutic interventions for PD.

Lipid peroxidation in the descending thoracic aorta of rats deprived of REM sleep using the inverted flowerpot technique

NEW FINDINGS

What is the central question of this study? Deprivation of rapid eye movement (REM) sleep is associated with increased oxidative stress, but its effects on the blood vessels are poorly documented. We investigated whether REM sleep deprivation induces oxidative stress and causes lipid peroxidation in the aorta. What is the main finding and its important? We demonstrate that REM sleep deprivation induces oxidative stress and mediates lipid peroxidation in the aorta. This can cause endothelial changes and increased blood pressure. These findings will contribute to the growing body of literature on the mechanism underlying the effects of sleep deprivation on cardiovascular disease.

ABSTRACT

Oxidative stress-mediated lipid peroxidation is a known cause of endothelial injury or dysfunction. Deprivation of rapid eye movement (REM) sleep is associated with oxidative stress. To date, the pathogenesis of increased blood pressure after sleep deprivation remains poorly understood, particularly in the REM sleep phase. Our aim was to investigate the effects of REM sleep deprivation on blood vessels in the REM sleep-deprived rat model. Twenty-eight male Sprague-Dawley rats were divided into four equal groups: free-moving control rats, rats deprived of REM sleep for 72 h (REMsd), tank control rats and 72 h sleep-recovered rats after 72 h of REM sleep deprivation. The rats were deprived of REM sleep using the inverted flowerpot technique. Food consumption, body weight gain and systolic blood pressure were monitored. At the end of the experiment, the descending thoracic aorta was isolated for the measurement of oxidative stress markers. Despite a significant increase in food consumption in the REMsd group compared with the other groups, there was a significant reduction in body weight gain. Systolic blood pressure also showed a significant increase in the REMsd group compared with the other groups. Superoxide dismutase activity was significantly lower and malondialdehyde concentrations significantly higher in the REMsd group compared with the other groups. Increased levels of malondialdehyde are suggestive of lipid peroxidation in the blood vessels, and oxidative stress may be attributed to the initiation of the process. The changes after REM sleep deprivation revert during sleep recovery. In conclusion, the findings of the present study provide convincing evidence that REM sleep deprivation induced lipid peroxidation, leading to endothelial damage.

[Sleep disturbance and cognitive dysfunction in patients with persistent postural and perceptual dizziness]

OBJECTIVE

To study sleep quality and cognitive status and their correlation in patients with persistent postural and perceptual dizziness (PPPD).

METHODS

We assessed sleep quality and cognitive function among 70 patients with PPPD and 70 age-matched heathy volunteers using Mini-Mental State Examination (MMSE), Montreal Cognitive Assessment (MoCA), Pittsburgh Sleep Quality Index and polysomnography (PSG).

RESULTS

The patients had a mean MMSE score of 25.10±3.87 and a mean MoCA score of 23.10±6.11, both suggesting mild cognitive impairment of the patients. The mean PSQI score of the patients was 14.60 ± 2.06, suggesting moderate insomnia among the patients. The MMSE scores in 3 dimensions (attention, memory and recall ability) and the dimension scores of MoCA for visual space and executive ability, attention and delayed recall all showed significant positive correlations with PSQI scores for sleep quality, sleep latency, sleep duration, sleep efficiency, sleep disorders and daytime dysfunction.

CONCLUSIONS

Moderate sleep disorder and mild cognitive dysfunction are common in PPPD patients. Sleep quality is correlated with cognitive function among these patients, suggesting that improving sleep quality of the patients helps to improve their cognitive function.

Omega-3 fatty acids protects against chronic sleep-deprivation induced memory impairment

AIMS

The current study aims to evaluate the possible protective effect of omega-3 fatty acids on memory impairment induced by sleep-deprivation in rats.

MATERIALS AND METHODS

Animals were chronically sleep deprived using the modified multiple platform model (8 h/day for 8 weeks). Omega-3 fatty acids were administered as fish oil via oral gavage at a daily dose of 100 mg omega-3 PUFA/100 g BWT. The spatial learning and memory were evaluated using the radial arm water maze (RAWM). Additionally, the following oxidative stress biomarkers were measured in the hippocampus: glutathione (GSH), oxidized glutathione (GSSG), GSH/GSSG, glutathione peroxidase (GPx), catalase, superoxide dismutase (SOD), and thiobarbituric acid reactive substance (TBARS).

KEY FINDINGS

Animals in the SD group committed significantly more errors in both short- and long- term memory tests of the RAWM compared to other groups. On the other hand, animals that were sleep deprived and treated with omega-3 fatty acids committed similar number of errors compared to the control group. This indicates that SD impaired both short- and long- term memories, and that chronic omega-3 fatty acids administration prevented these effects. Omega-3 fatty acids also prevented the decreases in hippocampal GPx, catalase and GSH/GSSG ratio and normalized the increases in GSSG levels, which were impaired by SD model. No changes were observed on hippocampal TBARS levels, or activity of SOD among experimental groups.

SIGNIFICANCE

In conclusion, a protective effect of omega-3 fatty acids administration has been observed against chronic SD-induced memory impairment probably via improving hippocampus antioxidant effects.

Transcranial near-infrared photobiomodulation attenuates memory impairment and hippocampal oxidative stress in sleep-deprived mice

Sleep deprivation (SD) causes oxidative stress in the hippocampus and subsequent memory impairment. In this study, the effect of near-infrared (NIR) photobiomodulation (PBM) on learning and memory impairment induced by acute SD was investigated. The mice were subjected to an acute SD protocol for 72 h. Simultaneously, NIR PBM using a laser at 810 nm was delivered (once a day for 3 days) transcranially to the head to affect the entire brain of mice. The Barnes maze and the What-Where-Which task were used to assess spatial and episodic-like memories. The hippocampal levels of antioxidant enzymes and oxidative stress biomarkers were evaluated. The results showed that NIR PBM prevented cognitive impairment induced by SD. Moreover, NIR PBM therapy enhanced the antioxidant status and increased mitochondrial activity in the hippocampus of SD mice. Our findings revealed that hippocampus-related mitochondrial damage and extensive oxidative stress contribute to the occurrence of memory impairment. In contrast, NIR PBM reduced hippocampal oxidative damage, supporting the ability of 810 nm laser light to improve the antioxidant defense system and maintain mitochondrial survival. This confirms that non-invasive transcranial NIR PBM therapy ameliorates hippocampal dysfunction, which is reflected in enhanced memory function.

L-carnitine prevents memory impairment induced by chronic REM-sleep deprivation

Sleep deprivation (SD) negatively impacts memory, which was related to oxidative stress induced damage. L-carnitine is a naturally occurring compound, synthesized endogenously in mammalian species and known to possess antioxidant properties. In this study, the effect of L-carnitine on learning and memory impairment induced by rapid eye movement sleep (REM-sleep) deprivation was investigated. REM-sleep deprivation was induced using modified multiple platform model (8h/day, for 6 weeks). Simultaneously, L-carnitine was administered (300mg/kg/day) intraperitoneally for 6 weeks. Thereafter, the radial arm water maze (RAWM) was used to assess spatial learning and memory. Additionally, the hippocampus levels of antioxidant biomarkers/enzymes: reduced glutathione (GSH), oxidized glutathione (GSSG), GSH/GSSG ratio, glutathione peroxidase (GPx), catalase, and superoxide dismutase (SOD) and thiobarbituric acid reactive substance (TBARS) were assessed. The results showed that chronic REM-sleep deprivation impaired both short- and long-term memory (P<0.05), whereas L-carnitine treatment protected against this effect. Furthermore, L-carnitine normalized chronic REM-sleep deprivation induced reduction in the hippocampus ratio of GSH/GSSG, activity of catalase, GPx, and SOD. No change was observed in TBARS among tested groups (P>0.05). In conclusion, chronic REM-sleep deprivation induced memory impairment, and treatment with L-carnitine prevented this impairment through normalizing antioxidant mechanisms in the hippocampus.

The effects of n-acetylcysteine and/or deferoxamine on manic-like behavior and brain oxidative damage in mice submitted to the paradoxal sleep deprivation model of mania

Bipolar disorder (BD) is a severe psychiatric disorder associated with social and functional impairment. Some studies have strongly suggested the involvement of oxidative stress in the pathophysiology of BD. Paradoxal sleep deprivation (PSD) in mice has been considered a good animal model of mania because it induces similar manic-like behavior, as well as producing the neurochemical alterations which have been observed in bipolar patients. Thus, the objective of the present study was to evaluate the effects of the antioxidant agent's n-acetylcysteine (Nac) and/or deferoxamine (DFX) on behavior and the oxidative stress parameters in the brains of mice submitted to the animal model of mania induced by PSD. The mice were treated for a period of seven days with saline solution (SAL), Nac, DFX or Nac plus DFX. The animals were subject to the PSD protocol for 36 h. Locomotor activity was then evaluated using the open-field test, and the oxidative stress parameters were subsequently evaluated in the hippocampus and frontal cortex of mice. The results showed PSD induced hyperactivity in mice, which is considered a manic-like behavior. In addition to this, PSD increased lipid peroxidation and oxidative damage to proteins, as well as causing alterations to antioxidant enzymes in the frontal cortex and hippocampus of mice. The Nac plus DFX adjunctive treatment prevented both the manic-like behavior and oxidative damage induced by PSD. Improving our understanding relating to oxidative damage in biomolecules, and the antioxidant mechanisms presented in the animal models of mania are important in helping to improve our knowledge concerning the pathophysiology and development of new therapeutical treatments for BD.

Sleep deprivation-induced multi-organ injury: role of oxidative stress and inflammation

Sleep deprivation affects all aspects of health. Adverse health effects by sleep deviation are still underestimated and undervalued in clinical practice and, to a much greater extent in monitoring human health. We hypothesized that sleep deprivation-induced mild organ injuries; oxidative stress and inflammation might play a crucial role in inducing multi-organ injury. Male C57BL/6J mice (n = 6-7) were sleep-deprived for 0-72 h using a modified multiple platform boxes method. Blood and tissue were collected. Liver, heart, kidney, lung, and pancreatic injuries were evaluated using biochemical and histological analyses. Glutamic oxaloacetic transaminase (GOT), glutamic pyruvic transaminase (GPT), total billirubin (TBIL), creatine phosphokinase (CPK), creatine phosphokinase-myocardial band (CKMB), lactic dehydrogenase (LDH), creatinine (CRE), and blood urea nitrogen (BUN) were assayed in blood. Malondialdehyde (MDA), nitric oxide (NO), tumor necrosis factor (TNF)-α, interleukin (IL)-1β, and IL-6 levels were measured. Histology revealed mild-to-moderate liver and lung injury in sleep-deprived mice. Sleep-deprived mice had significantly higher GOT, GPT, TBIL, CPK, CKMB, LDH, BUN, and α-amylase (AMYL) levels, which indicated liver, heart, kidney, and pancreatic injuries. Serum IL-1β at 24 h and IL-6 at 72 h were significantly higher in sleep-deprived than in control mice. Hepatic TNF-α and IL-1β were significantly higher, but IL-6 significantly lower in mice that had been sleep-deprived for 72 h. Sleep deprivation-mediated inflammation may be associated with mild to moderate multi-organ damage in mice. The implication of this study indicates sleep deprivation in humans may induce multi-organ injury that negatively affects cardiovascular and gastrointestinal health.

Sleep deprivation and oxidative stress in animal models: a systematic review

Because the function and mechanisms of sleep are partially clear, here we applied a meta-analysis to address the issue whether sleep function includes antioxidative properties in mice and rats. Given the expansion of the knowledge in the sleep field, it is indeed ambitious to describe all mammals, or other animals, in which sleep shows an antioxidant function. However, in this paper we reviewed the current understanding from basic studies in two species to drive the hypothesis that sleep is a dynamic-resting state with antioxidative properties. We performed a systematic review of articles cited in Medline, Scopus, and Web of Science until March 2015 using the following search terms: Sleep or sleep deprivation and oxidative stress, lipid peroxidation, glutathione, nitric oxide, catalase or superoxide dismutase. We found a total of 266 studies. After inclusion and exclusion criteria, 44 articles were included, which are presented and discussed in this study. The complex relationship between sleep duration and oxidative stress is discussed. Further studies should consider molecular and genetic approaches to determine whether disrupted sleep promotes oxidative stress.

The role of rapid eye movement sleep for amygdala-related memory processing

Over the years, rapid eye movement (REM) sleep has been associated with general memory consolidation, specific consolidation of perceptual, procedural, emotional and fear memories, brain maturation and preparation of waking consciousness. More recently, some of these associations (e.g., general and procedural memory consolidation) have been shown to be unlikely, while others (e.g., brain maturation and consciousness) remain inconclusive. In this review, we argue that both behavioral and neurophysiological evidence supports a role of REM sleep for amygdala-related memory processing: the amygdala-hippocampus-medial prefrontal cortex network involved in emotional processing, fear memory and valence consolidation shows strongest activity during REM sleep, in contrast to the hippocampus-medial prefrontal cortex only network which is more active during non-REM sleep. However, more research is needed to fully understand the mechanisms.