Prostaglandin D2 and sleep/wake regulation

Cyclooxygenase-2 (COX-2)-dependent mechanisms mediate sleep responses to microbial and thermal stimuli

Prostaglandins (PGs) play a crucial role in sleep regulation, yet the broader physiological context that leads to the activation of the prostaglandin-mediated sleep-promoting system remains elusive. In this study, we explored sleep-inducing mechanisms potentially involving PGs, including microbial, immune and thermal stimuli as well as homeostatic sleep responses induced by short-term sleep deprivation using cyclooxygenase-2 knockout (COX-2 KO) mice and their wild-type littermates (WT). Systemic administration of 0.4 µg lipopolysaccharide (LPS) induced increased non-rapid-eye movement sleep (NREMS) and fever in WT animals, these effects were completely absent in COX-2 KO mice. This finding underscores the essential role of COX-2-dependent prostaglandins in mediating sleep and febrile responses to LPS. In contrast, the sleep and fever responses induced by tumor necrosis factor α, a proinflammatory cytokine which activates COX-2, were preserved in COX-2 KO animals, indicating that these effects are independent of COX-2-related signaling. Additionally, we examined the impact of ambient temperature on sleep. The sleep-promoting effects of moderate warm ambient temperature were suppressed in COX-2 KO animals, resulting in significantly reduced NREMS at ambient temperatures of 30 °C and 35 °C compared to WT mice. However, rapid-eye-movement sleep responses to moderately cold or warm temperatures did not differ between the two genotypes. Furthermore, 6 h of sleep deprivation induced rebound increases in sleep with no significant differences observed between COX-2 KO and WT mice. This suggests that while COX-2-derived prostaglandins are crucial for the somnogenic effects of increased ambient temperature, the homeostatic responses to sleep loss are COX-2-independent. Overall, the results highlight the critical role of COX-2-derived prostaglandins as mediators of the sleep-wake and thermoregulatory responses to various physiological challenges, including microbial, immune, and thermal stimuli. These findings emphasize the interconnected regulation of body temperature and sleep, with peripheral mechanisms emerging as key players in these integrative processes.

Effects of low-dose acetylsalicylic acid on the inflammatory response to experimental sleep restriction in healthy humans

BACKGROUND

Sleep deficiencies, such as manifested in short sleep duration or insomnia symptoms, are known to increase the risk for multiple disease conditions involving immunopathology. Inflammation is hypothesized to be a mechanism through which deficient sleep acts as a risk factor for these conditions. Thus, one potential way to mitigate negative health consequences associated with deficient sleep is to target inflammation. Few interventional sleep studies investigated whether improving sleep affects inflammatory processes, but results suggest that complementary approaches may be necessary to target inflammation associated with sleep deficiencies. We investigated whether targeting inflammation through low-dose acetylsalicylic acid (ASA, i.e., aspirin) is able to blunt the inflammatory response to experimental sleep restriction.

METHODS

46 healthy participants (19F/27M, age range 19-63 years) were studied in a double-blind randomized placebo-controlled crossover trial with three protocols each consisting of a 14-day at-home monitoring phase followed by an 11-day (10-night) in-laboratory stay (sleep restriction/ASA, sleep restriction/placebo, control sleep/placebo). In the sleep restriction/ASA condition, participants took low-dose ASA (81 mg/day) daily in the evening (22:00) during the at-home phase and the subsequent in-laboratory stay. In the sleep restriction/placebo and control sleep/placebo conditions, participants took placebo daily. Each in-laboratory stay started with 2 nights with a sleep opportunity of 8 h/night (23:00-07:00) for adaptation and baseline measurements. Under the two sleep restriction conditions, participants were exposed to 5 nights of sleep restricted to a sleep opportunity of 4 h/night (03:00-07:00) followed by 3 nights of recovery sleep with a sleep opportunity of 8 h/night. Under the control sleep condition, participants had a sleep opportunity of 8 h/night throughout the in-laboratory stay. During each in-laboratory stay, participants had 3 days of intensive monitoring (at baseline, 5th day of sleep restriction/control sleep, and 2nd day of recovery sleep). Variables, including pro-inflammatory immune cell function, C-reactive protein (CRP), and actigraphy-estimated measures of sleep, were analyzed using generalized linear mixed models.

RESULTS

Low-dose ASA administration reduced the interleukin (IL)-6 expression in LPS-stimulated monocytes (p<0.05 for condition*day) and reduced serum CRP levels (p<0.01 for condition) after 5 nights of sleep restriction compared to placebo administration in the sleep restriction condition. Low-dose ASA also reduced the amount of cyclooxygenase (COX)-1/COX-2 double positive cells among LPS-stimulated monocytes after 2 nights of recovery sleep following 5 nights of sleep restriction compared to placebo (p<0.05 for condition). Low-dose ASA further decreased wake after sleep onset (WASO) and increased sleep efficiency (SE) during the first 2 nights of recovery sleep (p<0.001 for condition and condition*day). Baseline comparisons revealed no differences between conditions for all of the investigated variables (p>0.05 for condition).

CONCLUSION

This study shows that inflammatory responses to sleep restriction can be reduced by preemptive administration of low-dose ASA. This finding may open new therapeutic approaches to prevent or control inflammation and its consequences in those experiencing sleep deficiencies.

TRIAL REGISTRATION

ClinicalTrials.gov NCT03377543.

On the basis of sex and sleep: the influence of the estrous cycle and sex on sleep-wake behavior

The recurrent hormonal fluctuations within reproductive cycles impact sleep-wake behavior in women and in rats and mice used in preclinical models of sleep research. Strides have been made in sleep-related clinical trials to include equal numbers of women; however, the inclusion of female rodents in neuroscience and sleep research is lacking. Female animals are commonly omitted from studies over concerns of the effect of estrus cycle hormones on measured outcomes. This review highlights the estrous cycle's broad effects on sleep-wake behavior: from changes in sleep macroarchitecture to regionally specific alterations in neural oscillations. These changes are largely driven by cycle-dependent ovarian hormonal fluctuations occurring during proestrus and estrus that modulate neural circuits regulating sleep-wake behavior. Removal of estrous cycle influence by ovariectomy ablates characteristic sleep changes. Further, sex differences in sleep are present between gonadally intact females and males. Removal of reproductive hormones via gonadectomy in both sexes mitigates some, but not all sex differences. We examine the extent to which reproductive hormones and sex chromosomes contribute to sex differences in sleep-wake behavior. Finally, this review addresses the limitations in our understanding of the estrous cycle's impact on sleep-wake behavior, gaps in female sleep research that are well studied in males, and the implications that ignoring the estrous cycle has on studies of sleep-related processes.

Astrocyte atrophy induced by L-PGDS/PGD2/Src signaling dysfunction in the central amygdala mediates postpartum depression

BACKGROUND

Postpartum depression (PPD) is a serious psychiatric disorder that has significantly adverse impacts on maternal health. Metabolic abnormalities in the brain are associated with numerous neurological disorders, yet the specific metabolic signaling pathways and brain regions involved in PPD remain unelucidated.

METHODS

We performed behavioral test in the virgin and postpartum mice. We used mass spectrometry imaging (MSI) and targeted metabolomics analyses to investigate the metabolic alternation in the brain of GABAAR Delta-subunit-deficient (Gabrd-/-) postpartum mice, a specific preclinical animal model of PPD. Next, we performed mechanism studies including qPCR, Western blot, immunofluorescence staining, electron microscopy and primary astrocyte culture. In the specific knockdown and rescue experiments, we injected the adeno-associated virus into the central amygdala (CeA) of female mice.

RESULTS

We identified that prostaglandin D2 (PGD2) downregulation in the CeA was the most outstanding alternation in PPD, and then validated that lipocalin-type prostaglandin D synthase (L-PGDS)/PGD2 downregulation plays a causal role in depressive behaviors derived from PPD in both wild-type and Gabrd-/- mice. Furthermore, we verified that L-PGDS/PGD2 signaling dysfunction-induced astrocytes atrophy is mediated by Src phosphorylation both in vitro and in vivo.

LIMITATIONS

L-PGDS/PGD2 signaling dysfunction may be only responsible for the depressive behavior rather than maternal behaviors in the PPD, and it remains to be seen whether this mechanism is applicable to all depression types.

CONCLUSION

Our study identified abnormalities in the L-PGDS/PGD2 signaling in the CeA, which inhibited Src phosphorylation and induced astrocyte atrophy, ultimately resulting in the development of PPD in mice.

Prediction of Future Parkinson Disease Using Plasma Proteins Combined With Clinical-Demographic Measures

BACKGROUND AND OBJECTIVES

Identification of individuals at high risk of developing Parkinson disease (PD) several years before diagnosis is crucial for developing treatments to prevent or delay neurodegeneration. This study aimed to develop predictive models for PD risk that combine plasma proteins and easily accessible clinical-demographic variables.

METHODS

Using data from the UK Biobank (UKB), which recruited participants across the United Kingdom, we conducted a longitudinal study to identify predictors for incident PD. Participants with baseline plasma proteins and no PD were included. Through machine learning, we narrowed down predictors from a pool of 1,463 plasma proteins and 93 clinical-demographic. These predictors were then externally validated using the Parkinson's Progression Marker Initiative (PPMI) cohort. To further investigate the temporal trends of predictors, a nested case-control study was conducted within the UKB.

RESULTS

A total of 52,503 participants without PD (median age 58, 54% female) were included. Over a median follow-up duration of 14.0 years, 751 individuals were diagnosed with PD (median age 65, 37% female). Using a forward selection approach, we selected a panel of 22 plasma proteins for optimal prediction. Using an ensemble tree-based Light Gradient Boosting Machine (LightGBM) algorithm, the model achieved an area under the receiver operating characteristic curve (AUC) of 0.800 (95% CI 0.785-0.815). The LightGBM prediction model integrating both plasma proteins and clinical-demographic variables demonstrated enhanced predictive accuracy, with an AUC of 0.832 (95% CI 0.815-0.849). Key predictors identified included age, years of education, history of traumatic brain injury, and serum creatinine. The incorporation of 11 plasma proteins (neurofilament light, integrin subunit alpha V, hematopoietic PGD synthase, histamine N-methyltransferase, tubulin polymerization promoting protein family member 3, ectodysplasin A2 receptor, Latexin, interleukin-13 receptor subunit alpha-1, BAG family molecular chaperone regulator 3, tryptophanyl-TRNA synthetase, and secretogranin-2) augmented the model's predictive accuracy. External validation in the PPMI cohort confirmed the model's reliability, producing an AUC of 0.810 (95% CI 0.740-0.873). Notably, alterations in these predictors were detectable several years before the diagnosis of PD.

DISCUSSION

Our findings support the potential utility of a machine learning-based model integrating clinical-demographic variables with plasma proteins to identify individuals at high risk for PD within the general population. Although these predictors have been validated by PPMI, additional validation in a more diverse population reflective of the general community is essential.

Circadian Rhythms of the Blood-Brain Barrier and Drug Delivery

The blood-brain barrier (BBB) is a critical interface separating the central nervous system from the peripheral circulation, ensuring brain homeostasis and function. Recent research has unveiled a profound connection between the BBB and circadian rhythms, the endogenous oscillations synchronizing biological processes with the 24-hour light-dark cycle. This review explores the significance of circadian rhythms in the context of BBB functions, with an emphasis on substrate passage through the BBB. Our discussion includes efflux transporters and the molecular timing mechanisms that regulate their activities. A significant focus of this review is the potential implications of chronotherapy, leveraging our knowledge of circadian rhythms for improving drug delivery to the brain. Understanding the temporal changes in BBB can lead to optimized timing of drug administration, to enhance therapeutic efficacy for neurological disorders while reducing side effects. By elucidating the interplay between circadian rhythms and drug transport across the BBB, this review offers insights into innovative therapeutic interventions.

Functions and mechanisms of adenosine and its receptors in sleep regulation

Sleep is a natural and recurring state of life. Long-term insomnia can lead to physical and mental fatigue, inattention, memory loss, anxiety, depression and other symptoms, imposing immense public health and economic burden worldwide. The sleep and awakening regulation system is composed of many nerve nuclei and neurotransmitters in the brain, and it forms a neural network that interacts and restricts each other to regulate the occurrence and maintenance of sleep-wake. Adenosine (AD) is a neurotransmitter in the central nervous system and a driver of sleep. Meanwhile, the functions and mechanisms underlying sleep-promoting effects of adenosine and its receptors are still not entirely clear. However, in recent years, the increasing evidence indicated that adenosine can promote sleep through inhibiting arousal system and activating sleep-promoting system. At the same time, astrocyte-derived adenosine in modulating sleep homeostasis and sleep loss-induced related cognitive and memory deficits plays an important role. This review, therefore, summarizes the current research on the functions and possible mechanisms of adenosine and its receptors in the regulation of sleep and homeostatic control of sleep. Understanding these aspects will provide us better ideas on clinical problems such as insomnia, hypersomnia and other sleep disorders.

Hematopoietic Prostaglandin D Synthase Is Increased in Mast Cells and Pericytes in Autopsy Myocardial Specimens from Patients with Duchenne Muscular Dystrophy

The leading cause of death for patients with Duchenne muscular dystrophy (DMD), a progressive muscle disease, is heart failure. Prostaglandin (PG) D2, a physiologically active fatty acid, is synthesized from the precursor PGH2 by hematopoietic prostaglandin D synthase (HPGDS). Using a DMD animal model (mdx mice), we previously found that HPGDS expression is increased not only in injured muscle but also in the heart. Moreover, HPGDS inhibitors can slow the progression of muscle injury and cardiomyopathy. However, the location of HPGDS in the heart is still unknown. Thus, this study investigated HPGDS expression in autopsy myocardial samples from DMD patients. We confirmed the presence of fibrosis, a characteristic phenotype of DMD, in the autopsy myocardial sections. Additionally, HPGDS was expressed in mast cells, pericytes, and myeloid cells of the myocardial specimens but not in the myocardium. Compared with the non-DMD group, the DMD group showed increased HPGDS expression in mast cells and pericytes. Our findings confirm the possibility of using HPGDS inhibitor therapy to suppress PGD2 production to treat skeletal muscle disorders and cardiomyopathy. It thus provides significant insights for developing therapeutic drugs for DMD.

Association between idiopathic hypersomnia and a genetic variant in the PER3 gene

We aim to identify genetic markers associated with idiopathic hypersomnia, a disabling orphan central nervous system disorder of hypersomnolence that is still poorly understood. In our study, DNA was extracted from 79 unrelated patients diagnosed with idiopathic hypersomnia with long sleep time at the National Reference Center for Narcolepsy-France according to very stringent diagnostic criteria. Whole exome sequencing on the first 30 patients with idiopathic hypersomnia (25 females and 5 males) allowed the single nucleotide variants to be compared with a control population of 574 healthy subjects from the French Exome project database. We focused on the identification of genetic variants among 182 genes related to the regulation of sleep and circadian rhythm. Candidate variants obtained by exome sequencing analysis were then validated in a second sample of 49 patients with idiopathic hypersomnia (37 females and 12 males). Our study characterised seven variants from six genes significantly associated with idiopathic hypersomnia compared with controls. A targeted sequencing analysis of these seven variants on 49 other patients with idiopathic hypersomnia confirmed the relative over-representation of the A➔C variant of rs2859390, located in a potential splicing-site of PER3 gene. Our findings support a genetic predisposition and identify pathways involved in the pathogeny of idiopathic hypersomnia. A variant of the PER3 gene may predispose to idiopathic hypersomnia with long sleep time.

Application of Braided Piezoelectric Poly-l-Lactic Acid Cord Sensor to Sleep Bruxism Detection System with Less Physical or Mental Stress

For many years, we have been developing flexible sensors made of braided piezoelectric poly-l-lactic acid (PLLA) fibers that can be tied and untied for practical applications in society. To ensure good quality of sleep, the occurrence of bruxism has been attracting attention in recent years. Currently, there is a need for a system that can easily and accurately measure the frequency of bruxism at home. Therefore, taking advantage of the braided piezoelectric PLLA cord sensor's unique characteristic of being sewable, we aimed to provide a system that can measure the frequency of bruxism using the braided piezoelectric PLLA cord sensor simply sewn onto a bed sheet on which the subject lies down. After many tests using trial and error, the sheet sensor was completed with zigzag stitching. Twenty subjects slept overnight in a hospital room on sheets integrated with a braided piezoelectric PLLA cord. Polysomnography (PSG) was simultaneously performed on these subjects. The results showed that their bruxism could be detected with an accuracy of more than 95% compared with PSG measurements, which can only be performed in a hospital by a physician and are more burdensome for the subjects, with the subjects simply lying on the bed sheet with a braided piezoelectric PLLA cord sensor sewn into it.

Prolonged sleep deprivation induces a cytokine-storm-like syndrome in mammals

Most animals require sleep, and sleep loss induces serious pathophysiological consequences, including death. Previous experimental approaches for investigating sleep impacts in mice have been unable to persistently deprive animals of both rapid eye movement sleep (REMS) and non-rapid eye movement sleep (NREMS). Here, we report a "curling prevention by water" paradigm wherein mice remain awake 96% of the time. After 4 days of exposure, mice exhibit severe inflammation, and approximately 80% die. Sleep deprivation increases levels of prostaglandin D2 (PGD2) in the brain, and we found that elevated PGD2 efflux across the blood-brain-barrier-mediated by ATP-binding cassette subfamily C4 transporter-induces both accumulation of circulating neutrophils and a cytokine-storm-like syndrome. Experimental disruption of the PGD2/DP1 axis dramatically reduced sleep-deprivation-induced inflammation. Thus, our study reveals that sleep-related changes in PGD2 in the central nervous system drive profound pathological consequences in the peripheral immune system.

The vasoconstrictor activities of prostaglandin D2 via the thromboxane prostanoid receptor and E prostanoid receptor-3 outweigh its concurrent vasodepressor effect mainly through D prostanoid receptor-1 ex vivo and in vivo

Prostaglandin (PG) D2, a commonly considered vasodilator through D prostanoid receptor-1 (DP1), might also evoke vasoconstriction via acting on the thromboxane (Tx)-prostanoid receptor (the original receptor of TxA2; TP) and/or E prostanoid receptor-3 (one of the vasoconstrictor receptors of PGE2; EP3). This study aimed to test the above hypothesis in the mouse renal vascular bed (main renal arteries and perfused kidneys) and/or mesenteric resistance arteries and determine how the vasoconstrictor mechanism influences the overall PGD2 effect on systemic blood pressure under in vivo conditions. Experiments were performed on control wild-type (WT) mice and mice with deficiencies in TP (TP-/-) and/or EP3 (EP3-/-). Here we show that PGD2 indeed evoked vasoconstrictor responses in the above-mentioned tissues of WT mice, which were however not only reduced by TP-/- or EP3-/-, but also reversed by TP-/-/EP3-/- in some of the above tissues (mesenteric resistance arteries or perfused kidneys) to dilator reactions that were reduced by non-selective DP antagonism. A slight or mild pressor response was also observed with PGD2 under in vivo conditions, and this was again reversed to a depressor response in TP-/- or TP-/-/EP3-/- mice. Non-selective DP antagonism reduced the PGD2-evoked depressor response in TP-/-/EP3-/- mice as well. These results thus demonstrate that like other PGs, PGD2 activates TP and/or EP3 to evoke vasoconstrictor activities, which can outweigh its concurrent vasodepressor activity mediated mainly through DP1, and hence result in a pressor response, although the response might only be of a slight or mild extent.

Impact of antiallergy agents on CPAP therapy and sleep quality with spring pollinosis in Japanese

PURPOSE

Allergic rhinitis (AR) is associated with obstructive sleep apnea (OSA) and nasal obstruction causes decreased adherence to continuous positive airway pressure (CPAP). The purpose is to evaluate the effects of antiallergic agents on CPAP adherence and sleep quality.

METHODS

A longitudinal study was made of patients who use CPAP for OSA and treated with antiallergy agents for spring pollinosis. We compared the Pittsburgh Sleep Quality Index (PSQI), Epworth Sleepiness Scale (ESS), nasal symptoms scores (NSS), and data from CPAP before and after treatment. Then, we classified the subjects into two groups based on the baseline PSQI score: one group without a decreased sleep quality (PSQI < 6) and the other group with decreased sleep quality (PSQI ≥ 6).

RESULTS

Of 28 subjects enrolled, 13 had good sleep quality and 15 had poor sleep quality. PSQI showed significant improvements after medication (p = 0.046). ESS showed no significant differences after AR medication (p = 0.565). Significant improvement was observed after the prescription of antiallergy agents in all items of NSS (sneezing, p < 0.05; rhinorrhea, p < 0.01; nasal obstruction, p < 0.01; QOL, p < 0.01). The percentage of days with CPAP use more than 4 h increased significantly after the administration of rhinitis medication (p = 0.022). In the intragroup comparisons of PSQI ≥ 6 group, PSQI decreased significantly (p < 0.05). For the NSS in intragroup comparisons of PSQI ≥ 6 group, all parameters showed significant improvement (sneezing, p = 0.016; rhinorrhea, p = 0.005; nasal obstruction, p < 0.005; QOL, p < 0.005).

CONCLUSION

The use of antiallergy agents can improve CPAP adherence and sleep quality in patients with OSA on CPAP.

Sleep Patterns, Plasma Metabolome, and Risk of Incident Type 2 Diabetes Mellitus

CONTEXT

A healthy sleep pattern has been related to a lower risk of type 2 diabetes mellitus (T2DM).

OBJECTIVE

We aimed to identify the metabolomic signature for the healthy sleep pattern and assess its potential causality with T2DM.

METHODS

This study included 78 659 participants with complete phenotypic data (sleep information and metabolomic measurements) from the UK Biobank study. Elastic net regularized regression was applied to calculate a metabolomic signature reflecting overall sleep patterns. We also performed genome-wide association analysis of the metabolomic signature and one-sample mendelian randomization (MR) with T2DM risk.

RESULTS

During a median of 8.8 years of follow-up, we documented 1489 incident T2DM cases. Compared with individuals who had an unhealthy sleep pattern, those with a healthy sleep pattern had a 49% lower risk of T2DM (multivariable-adjusted hazard ratio [HR], 0.51; 95% CI, 0.40-0.63). We further constructed a metabolomic signature using elastic net regularized regressions that comprised 153 metabolites, and robustly correlated with sleep pattern (r = 0.19; P = 3×10-325). In multivariable Cox regressions, the metabolomic signature showed a statistically significant inverse association with T2DM risk (HR per SD increment in the signature, 0.56; 95% CI, 0.52-0.60). Additionally, MR analyses indicated a significant causal relation between the genetically predicted metabolomic signature and incident T2DM (P for trend < .001).

CONCLUSION

In this large prospective study, we identified a metabolomic signature for the healthy sleep pattern, and such a signature showed a potential causality with T2DM risk independent of traditional risk factors.

Computer-Aided Designing Peptide Inhibitors of Human Hematopoietic Prostaglandin D2 Synthase Combined Molecular Docking and Molecular Dynamics Simulation

Human hematopoietic prostaglandin D2 synthase (HPGDS) is involved in the production of prostaglandin D2, which participates in various physiological processes, including inflammation, allergic reactions, and sleep regulation. Inhibitors of HPGDS have been investigated as potential anti-inflammatory agents. For the investigation of potent HPGDS inhibitors, we carried out a computational modeling study combining molecular docking and molecular dynamics simulation for selecting and virtual confirming the designed binders. We selected the structure of HPGDS (PDB ID: 2CVD) carrying its native inhibitor compound HQL as our research target. The random 5-mer peptide library was created by building the 3-D structure of random peptides using Rosetta Buildpeptide and performing conformational optimization. Molecular docking was carried out by accommodating the peptides into the location of their native binder and then conducting docking using FlexPepDock. The two peptides RMYYY and VMYMI, which display the lowest binding energy against HPGDS, were selected to perform a comparative study. The interaction of RMYYY and VMYMI against HPGDS was further confirmed using molecular dynamics simulation and aligned with its native binder, HQL. We show the selected binders to have stronger binding energy and more frequent interactions against HPGDS than HQL. In addition, we analyzed the solubility, hydrophobicity, charge, and bioactivity of the generated peptides, and we show that the selected strong binder may be further used as therapeutic drugs.

Non-esterified erythrocyte linoleic acid, arachidonic acid, and subjective sleep outcomes

OBJECTIVE

This study investigated whether non-esterified erythrocyte omega-6 PUFAs were associated with subjective assessment of sleep quality and duration, and risk for obstructive sleep apnea.

METHODS

In this secondary analysis of the cross-sectional OPPERA-II study, 538 adults completed the Pittsburgh Sleep Quality Index (PSQI), reported their usual hours of sleep, and answered STOP screening questions for obstructive sleep apnea. Circulating non-esterified erythrocyte concentrations of omega-6 PUFA linoleic acid and arachidonic acid were quantified by liquid chromatography tandem mass spectroscopy. Sleep outcomes were dichotomized as poor (PSQI ≤5) vs good (PSQI ≥6) sleep quality, insufficient or excessive (≤6 or >9 h) vs good (7-9 h) sleep duration, and high (≥2 affirmative responses) vs low (<2 affirmative responses) risk for obstructive sleep apnea. Non-esterified omega-6 PUFAs and the continuous covariates of body mass index, Short Form (SF) 12 Health Survey Physical and Mental Component scores and resting measures of systolic and diastolic blood pressure were standardized for multivariable analysis. Categorical covariates were study site, age, sex, and race/ethnicity. Multivariable-adjusted logistic regression first estimated odds ratios (OR) and 95% confidence limits (CL) for sleep outcomes using linoleic acid as the main exposure. Analysis was then repeated using arachidonic acid as the main exposure.

RESULTS

In the multivariable-adjusted model, each standard deviation increase in non-esterified erythrocyte linoleic acid was associated with higher odds of poor sleep quality (OR=1.2, 95% CL: 1.1, 1.5), insufficient or excessive sleep (OR= 1.3, 95% CL: 1.1, 1.6) and high-risk for obstructive sleep apnea (OR=1.3, 95% CL: 1.1, 1.6). Likewise, for each standard deviation increase in non-esterified erythrocyte arachidonic acid, odds increased of poor sleep quality (OR=1.2, 95% CL: 1.1, 1.5), and insufficient or excessive sleep (OR=1.2, 95% CL: 1.1, 1.5). Odds of being high risk for obstructive sleep apnea increased with greater circulating arachidonic acid, but the association did not reach statistical significance (OR=1.1, 95% CL: 0.9, 1.4).

CONCLUSION

Non-esterified erythrocyte linoleic acid and arachidonic acid were associated with poor sleep quality and insufficient or excessive sleep duration. Linoleic acid, but not arachidonic acid, was also associated with high risk for obstructive sleep apnea.

Role of astrocytes in sleep deprivation: accomplices, resisters, or bystanders?

Sleep plays an essential role in all studied animals with a nervous system. However, sleep deprivation leads to various pathological changes and neurobehavioral problems. Astrocytes are the most abundant cells in the brain and are involved in various important functions, including neurotransmitter and ion homeostasis, synaptic and neuronal modulation, and blood-brain barrier maintenance; furthermore, they are associated with numerous neurodegenerative diseases, pain, and mood disorders. Moreover, astrocytes are increasingly being recognized as vital contributors to the regulation of sleep-wake cycles, both locally and in specific neural circuits. In this review, we begin by describing the role of astrocytes in regulating sleep and circadian rhythms, focusing on: (i) neuronal activity; (ii) metabolism; (iii) the glymphatic system; (iv) neuroinflammation; and (v) astrocyte-microglia cross-talk. Moreover, we review the role of astrocytes in sleep deprivation comorbidities and sleep deprivation-related brain disorders. Finally, we discuss potential interventions targeting astrocytes to prevent or treat sleep deprivation-related brain disorders. Pursuing these questions would pave the way for a deeper understanding of the cellular and neural mechanisms underlying sleep deprivation-comorbid brain disorders.

Attenuation of Laser-Induced Choroidal Neovascularization by Blockade of Prostaglandin D2 Receptor 2

Purpose

The purpose of this study was to investigate the impact of prostaglandin D2 (PGD2) receptor 2 (DP2) on choroidal neovascularization (CNV) formation in mice.

Methods

Using a laser-induced CNV model, the CNV size of wild-type (WT) mice treated with DP2 antagonist (CAY10471 or OC000459) was compared with that of untreated mice. Vascular endothelial growth factor (VEGF) and MCP-1 levels were also compared between the two groups. Similar experiments were performed comparing DP2 knockout (DP2KO) mice with WT mice (8 and 56 weeks old). The number of infiltrating macrophages to laser spots was also compared between the WT and DP2KO mice. We administered a DP2 antagonist to 15-methyl PGD2 (a DP2 agonist)-stimulated ARPE-19 cells and measured VEGF secretion by enzyme-linked immunosorbent assay. Tube formation assay was performed on human umbilical vein endothelial cells with or without a DP2 antagonist.

Results

CNV sizes were significantly smaller in mice treated with CAY10471 or OC000459 than in those treated with vehicle. Similarly, the CNV size of DP2KO mice was significantly smaller than that of WT mice. The number of macrophages at laser spots in DP2KO mice was significantly lower than that in WT mice. The VEGF concentration of lasered DP2KO mice's eyes was significantly lower than that of lasered WT mice' eyes. DP2 antagonist treatment suppressed VEGF secretion in ARPE-19 cells under 15-methyl PGD2 stimulation. The tube formation assay suggested that lumen formation was inhibited by a DP2 antagonist.

Conclusions

DP2 blockade attenuated choroidal neovascularization.

Translational Relevance

Drugs targeting DP2 are potentially a novel treatment for age-related macular degeneration.

Adenosine A2A receptors and sleep

Adenosine, a known endogenous somnogen, induces sleep via A1 and A2A receptors. In this chapter, we review the current knowledge regarding the role of the adenosine A2A receptor and its agonists, antagonists, and allosteric modulators in sleep-wake regulation. Although many adenosine A2A receptor agonists, antagonists, and allosteric modulators have been identified, only a few have been tested to see if they can promote sleep or wakefulness. In addition, the growing popularity of natural sleep aids has led to an investigation of natural compounds that may improve sleep by activating the adenosine A2A receptor. Finally, we discuss the potential therapeutic advantage of allosteric modulators of adenosine A2A receptors over classic agonists and antagonists for treating sleep and neurologic disorders.

Prostaglandin D2 Controls Local Blood Flow and Sleep-Promoting Neurons in the VLPO via Astrocyte-Derived Adenosine

Prostaglandin D₂ (PGD₂) is one of the most potent endogenous sleep-promoting molecules. However, the cellular and molecular mechanisms of the PGD₂-induced activation of sleep-promoting neurons in the ventrolateral preoptic nucleus (VLPO), the major nonrapid eye movement (NREM)-sleep center, still remains unclear. We here show that PGD₂ receptors (DP₁) are not only expressed in the leptomeninges but also in astrocytes from the VLPO. We further demonstrate, by performing real-time measurements of extracellular adenosine using purine enzymatic biosensors in the VLPO, that PGD₂ application causes a 40% increase in adenosine level, via an astroglial release. Measurements of vasodilatory responses and electrophysiological recordings finally reveal that, in response to PGD₂ application, adenosine release induces an A_2AR-mediated dilatation of blood vessels and activation of VLPO sleep-promoting neurons. Altogether, our results unravel the PGD₂ signaling pathway in the VLPO, controlling local blood flow and sleep-promoting neurons, via astrocyte-derived adenosine.

Association of Hypovitaminosis D with Sleep Parameters in Rotating Shift Worker Drivers

Objective  To evaluate the association between sleep parameters and hypovitaminosis D in rotating shift drivers. Material and Methods  We conducted a cross-sectional study on 82 male rotating shift workers (24-57 years old) with at least one cardiovascular risk factor (such as hyperglycemia, dyslipidemia, abdominal obesity, physical inactivity, hypertension, and smoking). Polysomnography was used to evaluate sleep parameters. Logistic regression was used to model the association between hypovitaminosis D and sleep parameters after adjustment for relevant covariates. Results  Hypovitaminosis D (< 20 ng/mL) was seen in 30.5% of the workers. Shift workers with hypovitaminosis D had lower sleep efficiency (odds ratio [OR]: 3.68; 95% confidence interval [CI]: 1.95-5.53), lower arterial oxygen saturation (OR: 5.35; 95% CI: 3.37-6.12), and increased microarousal index (OR: 3.85; 95% CI: 1.26-5.63) after adjusting. Conclusion  We suggest that hypovitaminosis D is associated with greater sleep disturbances in rotating shift workers.

Oligodendrocyte-lineage cell exocytosis and L-type prostaglandin D synthase promote oligodendrocyte development and myelination

In the developing central nervous system, oligodendrocyte precursor cells (OPCs) differentiate into oligodendrocytes, which form myelin around axons. Oligodendrocytes and myelin are essential for the function of the central nervous system, as evidenced by the severe neurological symptoms that arise in demyelinating diseases such as multiple sclerosis and leukodystrophy. Although many cell-intrinsic mechanisms that regulate oligodendrocyte development and myelination have been reported, it remains unclear whether interactions among oligodendrocyte-lineage cells (OPCs and oligodendrocytes) affect oligodendrocyte development and myelination. Here, we show that blocking vesicle-associated membrane protein (VAMP) 1/2/3-dependent exocytosis from oligodendrocyte-lineage cells impairs oligodendrocyte development, myelination, and motor behavior in mice. Adding oligodendrocyte-lineage cell-secreted molecules to secretion-deficient OPC cultures partially restores the morphological maturation of oligodendrocytes. Moreover, we identified L-type prostaglandin D synthase as an oligodendrocyte-lineage cell-secreted protein that promotes oligodendrocyte development and myelination in vivo. These findings reveal a novel autocrine/paracrine loop model for the regulation of oligodendrocyte and myelin development.

Natural-Derived COX-2 Inhibitors as Anticancer Drugs: A Review of their Structural Diversity and Mechanism of Action

Cyclooxygenase-2 (COX-2) is a key-type enzyme playing a crucial role in cancer development, making it a target of high interest for drug designers. In the last two decades, numerous selective COX-2 inhibitors have been approved for various clinical conditions. However, data from clinical trials propose that the prolonged use of COX-2 inhibitors is associated with life-threatening cardiovascular side effects. The data indicate that a slight structural modification can help develop COX-2 selective inhibitors with comparative efficacy and limited side effects. In this regard, secondary metabolites from natural sources offer great hope for developing novel COX-2 inhibitors with potential anticancer activity. In recent years, various nature-derived organic scaffolds are being explored as leads for developing new COX-2 inhibitors. The current review attempts to highlight the COX-2 inhibition activity of some naturally occurring secondary metabolites, concerning their capacity to inhibit COX-1 and COX-2 enzymes and inhibit cancer development, aiming to establish a structure-activity relationship.

Major depressive disorder (mdd): emerging immune targets at preclinical level

BACKGROUND

Major depressive disorder is a mental health disorder that is characterized by a persistently low mood and loss of interest. MDD is affecting over 3.8% of the global population as a major health problem. Its etiology is complex, and involves the interaction between a number of factors, including genetic predisposition and the presence of environmental stresses.

AREAS COVERED

The role of the immune and inflammatory systems in depression has been gaining interest, with evidence suggesting the potential involvement of pro-inflammatory molecules like TNF, interleukins, prostaglandins, and other cytokines, among others, has been put forth. Along with this, the potential of agents, from NSAIDs to antibiotics, are being evaluated in therapy for depression. The current review will discuss emerging immune targets at the preclinical level.

EXPERT OPINION

With increasing evidence to show that immune and inflammatory mediators are implicated in MDD, increasing research toward their potential as drug targets is encouraged. At the same time, agents acting on these mediators and possessing anti-inflammatory potential are also being evaluated as future therapeutic options for MDD, and increasing focus toward non-conventional drugs which can act through these mechanisms is important as regards the future prospects of the use of anti-inflammatory agents in depression.

Prostanoid Metabolites as Biomarkers in Human Disease

Prostaglandins (PGD₂, PGE₂, PGF_2α), prostacyclin (PGI₂), and thromboxane A₂ (TXA₂) together form the prostanoid family of lipid mediators. As autacoids, these five primary prostanoids propagate intercellular signals and are involved in many physiological processes. Furthermore, alterations in their biosynthesis accompany a wide range of pathological conditions, which leads to substantially increased local levels during disease. Primary prostanoids are chemically instable and rapidly metabolized. Their metabolites are more stable, integrate the local production on a systemic level, and their analysis in various biological matrices yields valuable information under different pathological settings. Therefore, prostanoid metabolites may be used as diagnostic, predictive, or prognostic biomarkers in human disease. Although their potential as biomarkers is great and extensive research has identified major prostanoid metabolites that serve as target analytes in different biofluids, the number of studies that correlate prostanoid metabolite levels to disease outcome is still limited. We review the metabolism of primary prostanoids in humans, summarize the levels of prostanoid metabolites in healthy subjects, and highlight existing biomarker studies. Since analysis of prostanoid metabolites is challenging because of ongoing metabolism and limited half-lives, an emphasis of this review lies on the reliable measurement and interpretation of obtained levels.

Lipocalin-Type Prostaglandin D2 Synthase Protein- A Central Player in Metabolism

Lipocalin-type prostaglandin D synthase was previously known as β-trace protein (BTP), a low-molecular-weight glycoprotein that is heavily expressed in human cerebrospinal fluid. Nevertheless, it is also seen to be expressed in numerous other tissues including the kidney, liver, lung, heart, adipose, muscle, and pancreas. Functionally, L-PGDS behaves like a lipocalin type protein where it helps in binding and transportation of small lipophilic substances, such as steroids, retinoids, and other lipophilic ligands. Enzymatically, L-PGDS functions as a prostaglandin synthase where it helps in the production of PGD₂ by catalyzing the isomerization of PGH₂, a common precursor of the two series of prostaglandins. PGD₂ regulates its physiological function through two individual receptors named DP1 and DP2. L-PGDS has been a central player in many diseases, its role in metabolism including diabetes, fatty liver disease, and obesity has gathered a large attention. In this review, we summarize the current state of knowledge about L-PGDS and it's signaling in adipose, hepatic, skeletal muscle, and pancreas tissues, which are core targets for metabolic studies. Modulation of L-PGDS signaling can be considered as a potential future therapeutic target for the treatment of insulin resistance as well as fatty liver disease.

GPR39 Deficiency Impairs Memory and Alters Oxylipins and Inflammatory Cytokines Without Affecting Cerebral Blood Flow in a High-Fat Diet Mouse Model of Cognitive Impairment

Vascular cognitive impairment (VCI) is the second most common cause of dementia. There is no treatment for VCI, in part due to a lack of understanding of the underlying mechanisms. The G-protein coupled receptor 39 (GPR39) is regulated by arachidonic acid (AA)-derived oxylipins that have been implicated in VCI. Furthermore, GPR39 is increased in microglia of post mortem human brains with VCI. Carriers of homozygous GPR39 SNPs have a higher burden of white matter hyperintensity, an MRI marker of VCI. We tested the hypothesis that GPR39 plays a protective role against high-fat diet (HFD)-induced cognitive impairment, in part mediated via oxylipins actions on cerebral blood flow (CBF) and neuroinflammation. Homozygous (KO) and heterozygous (Het) GPR39 knockout mice and wild-type (WT) littermates with and without HFD for 8 months were tested for cognitive performance using the novel object recognition (NOR) and the Morris water maze (MWM) tests, followed by CBF measurements using MRI. Brain tissue and plasma oxylipins were quantified with high-performance liquid chromatography coupled to mass spectrometry. Cytokines and chemokines were measured using a multiplex assay. KO mice, regardless of diet, swam further away from platform location in the MWM compared to WT and Het mice. In the NOR test, there were no effects of genotype or diet. Brain and plasma AA-derived oxylipins formed by 11- and 15-lipoxygenase (LOX), cyclooxygenase (COX) and non-enzymatically were increased by HFD and GPR39 deletion. Interleukin-10 (IL-10) was lower in KO mice on HFD than standard diet (STD), whereas IL-4, interferon γ-induced protein-10 (IP-10) and monocyte chemotactic protein-3 (MCP-3) were altered by diet in both WT and KO, but were not affected by genotype. Resting CBF was reduced in WT and KO mice on HFD, with no change in vasoreactivity. The deletion of GPR39 did not change CBF compared to WT mice on either STD or HFD. We conclude that GPR39 plays a role in spatial memory retention and protects against HFD-induced cognitive impairment in part by modulating inflammation and AA-derived oxylipins. The results indicate that GPR39 and oxylipin pathways play a role and may serve as therapeutic targets in VCI.

Neurobiology of dream activity and effects of stimulants on dreams

The sleep-wake cycle is the result of the activity of a multiple neurobiological network interaction. Dreaming feature is one interesting sleep phenomena that represents sensorial components, mostly visual perceptions, accompanied with intense emotions. Further complexity has been added to the topic of the neurobiological mechanism of dreams generation by the current data that suggests the influence of drugs on dream generation. Here, we discuss the review on some of the neurobiological mechanism of the regulation of dream activity, with special emphasis on the effects of stimulants on dreaming.

Sleep Quality: A Narrative Review on Nutrition, Stimulants, and Physical Activity as Important Factors

Sleep is a cyclically occurring, transient, and functional state that is controlled primarily by neurobiological processes. Sleep disorders and insomnia are increasingly being diagnosed at all ages. These are risk factors for depression, mental disorders, coronary heart disease, metabolic syndrome, and/or high blood pressure. A number of factors can negatively affect sleep quality, including the use of stimulants, stress, anxiety, and the use of electronic devices before sleep. A growing body of evidence suggests that nutrition, physical activity, and sleep hygiene can significantly affect the quality of sleep. The aim of this review was to discuss the factors that can affect sleep quality, such as nutrition, stimulants, and physical activity.

Median preoptic GABA and glutamate neurons exert differential control over sleep behavior

Previous studies suggest that the median preoptic nucleus (MnPO) of the hypothalamus plays an important role in regulating the wake-sleep cycle and, in particular, homeostatic sleep drive. However, the precise cellular phenotypes, targets, and central mechanisms by which the MnPO neurons regulate the wake-sleep cycle remain unknown. Both excitatory and inhibitory MnPO neurons innervate brain regions implicated in sleep promotion and maintenance, suggesting that both cell types may participate in sleep control. Using genetically targeted approaches, we investigated the role of the MnPO GABAergic (MnPO^Vgat) and glutamatergic (MnPO^Vglut2) neurons in modulating wake-sleep behavior of mice. We found that both neuron populations differentially participate in wake-sleep control, with MnPO^Vgat neurons being involved in sleep homeostasis and MnPO^Vglut2 neurons facilitating sleep during allostatic (stressful) challenges.

Therapeutic and Prognostic Significance of Arachidonic Acid in Heart Failure

BACKGROUND

Accurate prediction of death is an unmet need in patients with acute decompensated heart failure (HF). Arachidonic acid (AA) metabolites play an important role in the multiple pathophysiological processes. We aimed to develop an AA score to accurately predict mortality in patients with acute decompensated HF and explore the causal relationship between the AA predictors and HF.

METHODS

The serum AA metabolites was measured in patients with acute decompensated HF (discovery cohort n=419; validation cohort n=386) by mass spectroscopy. We assessed the prognostic importance of AA metabolites for 1-year death using Cox regression and machine learning approaches. An machine learning-based AA score for predicting 1-year death was created and validated. We explored the mechanisms using transcriptome and functional experiments in a mouse model of early ischemic cardiomyopathy.

RESULTS

Among the 27 AA metabolites, elevated 14,15-DHET/14,15-EET ratio was the strongest predictor of 1-year death (hazard ratio, 2.10, P=3.1×10^-6). Machine learning-based AA score using a combination of the 14,15-DHET/14,15-EET ratio, 14,15-DHET, PGD2, and 9-HETE performed best (area under the curve [AUC]: 0.85). The machine learning-based AA score provided incremental information to predict mortality beyond BNP (B-type natriuretic peptide; ΔAUC: 0.19), clinical score (ΔAUC: 0.09), and preexisting ADHERE, Organized Program to Initiate Lifesaving Treatment in Hospitalized Patients With Heart Failure, and Get With The Guidelines Heart Failure scores (ΔAUC: 0.17, 0.17, 0.15, respectively). In the validation cohort, the AA score accurately predicted mortality (AUC:0.81). False-negative and false-positive findings, as classified by the BNP threshold, were correctly reclassified by the AA score (46.2% of false-negative and 84.5% of false-positive). In a murine model, the expression and enzymatic activity of sEH (soluble epoxide hydrolase) increased after myocardial infarction. Genetic deletion of sEH improved HF and the blockade of 14,15-EET abolished this cardioprotection. We mechanistically revealed the beneficial effect of 14,15-EET by impairing the activation of monocytes/macrophages.

CONCLUSIONS

Our studies propose that the AA score predicts death in patients with acute decompensated HF and inhibiting sEH serves as a therapeutic target for treating HF.

REGISTRATION

URL: https://www.

CLINICALTRIALS

gov; Unique identifier: NCT04108182.

The Sleep-Promoting Ventrolateral Preoptic Nucleus: What Have We Learned over the Past 25 Years?

For over a century, the role of the preoptic hypothalamus and adjacent basal forebrain in sleep-wake regulation has been recognized. However, for years, the identity and location of sleep- and wake-promoting neurons in this region remained largely unresolved. Twenty-five years ago, Saper and colleagues uncovered a small collection of sleep-active neurons in the ventrolateral preoptic nucleus (VLPO) of the preoptic hypothalamus, and since this seminal discovery the VLPO has been intensively investigated by labs around the world, including our own. Herein, we first review the history of the preoptic area, with an emphasis on the VLPO in sleep-wake control. We then attempt to synthesize our current understanding of the circuit, cellular and synaptic bases by which the VLPO both regulates and is itself regulated, in order to exert a powerful control over behavioral state, as well as examining data suggesting an involvement of the VLPO in other physiological processes.

Catalysis-Enabled Concise and Stereoselective Total Synthesis of the Tricyclic Prostaglandin D2 Metabolite Methyl Ester

A concise and stereoselective total synthesis of the clinically relevant tricyclic prostaglandin D2 metabolite (tricyclic-PGDM) methyl ester in racemic form was accomplished in eight steps from a readily available known cyclopentene-diol derivative. The synthesis features a nickel-catalyzed Ueno-Stork-type dicarbofunctionalization to generate two consecutive stereocenters, a palladium-catalyzed carbonylative spirolactonization to build the core oxaspirolactone, and a Z-selective cross-metathesis to introduce the (Z)-3-butenoate side chain, a group challenging to introduce through traditional Wittig protocols and troublesome for the two previous total syntheses. A general Z-selective cross-metathesis protocol to construct (Z)-β,γ-unsaturated esters was also developed that has broad functional group tolerance and high stereoselectivity. Additionally, our synthesis already accumulated 75 mg of valuable material for an 18 O-tricyclic-PGDM-based assay used in clinical settings for inflammation.

Functional brain maturation and sleep organisation in neonates with congenital heart disease

OBJECTIVE

Neonates with Congenital Heart Disease (CHD) have structural delays in brain development. To evaluate whether functional brain maturation and sleep-wake physiology is also disturbed, the Functional Brain Age (FBA) and sleep organisation on EEG during the neonatal period is investigated.

METHODS

We compared 15 neonates with CHD who underwent multichannel EEG with healthy term newborns of the same postmenstrual age, including subgroup analysis for d-Transposition of the Great Arteries (d-TGA) (n = 8). To estimate FBA, a prediction tool using quantitative EEG features as input, was applied. Second, the EEG was automatically classified into the 4 neonatal sleep stages. Neonates with CHD underwent neurodevelopmental testing using the Bayley Scale of Infant Development-III at 24 months.

RESULTS

Preoperatively, the FBA was delayed in CHD infants and more so in d-TGA infants. The FBA was positively correlated with motor scores. Sleep organisation was significantly altered in neonates with CHD. The duration of the sleep cycle and the proportion of Active Sleep Stage 1 was decreased, again more marked in the d-TGA infants. Neonates with d-TGA spent less time in High Voltage Slow Wave Sleep and more in Tracé Alternant compared to healthy terms. Both FBA and sleep organisation normalised postoperatively. The duration of High Voltage Slow Wave Sleep remained positively correlated with motor scores in d-TGA infants.

INTERPRETATION

Altered early brain function and sleep is present in neonates with CHD. These results are intruiging, as inefficient neonatal sleep has been linked with adverse long-term outcome. Identifying how these rapid alterations in brain function are mitigated through improvements in cerebral oxygenation, surgery, drugs and nutrition may have relevance for clinical practice and outcome.

PUFA ω-3 and ω-6 biomarkers and sleep: a pooled analysis of cohort studies on behalf of the Fatty Acids and Outcomes Research Consortium (FORCE)

BACKGROUND

n-3 and n-6 PUFAs have physiologic roles in sleep processes, but little is known regarding circulating n-3 and n-6 PUFA and sleep parameters.

OBJECTIVES

We sought to assess associations between biomarkers of n-3 and n-6 PUFA intake with self-reported sleep duration and difficulty falling sleeping in the Fatty Acids and Outcome Research Consortium.

METHODS

Harmonized, de novo, individual-level analyses were performed and pooled across 12 cohorts. Participants were 35-96 y old and from 5 nations. Circulating measures included α-linolenic acid (ALA), EPA, docosapentaenoic acid (DPA), DHA, EPA + DPA + DHA, linoleic acid, and arachidonic acid. Sleep duration (10 cohorts, n = 18,791) was categorized as short (≤6 h), 7-8 h (reference), or long (≥9 h). Difficulty falling asleep (8 cohorts, n = 12,500) was categorized as yes or no. Associations between PUFAs, sleep duration, and difficulty falling sleeping were assessed by cross-sectional multinomial logistic regression using standardized protocols and covariates. Cohort-specific multivariable-adjusted ORs per quintile of PUFAs were pooled with inverse-variance weighted meta-analysis.

RESULTS

In pooled analysis adjusted for sociodemographic characteristics and health status, participants with higher very long-chain n-3 PUFAs were less likely to have long sleep duration. In the top compared with the bottom quintiles, the multivariable-adjusted ORs (95% CIs) for long sleep were 0.78 (95% CI: 0.65, 0.95) for DHA and 0.76 (95% CI: 0.63, 0.93) for EPA + DPA + DHA. Significant associations for ALA and n-6 PUFA with short sleep duration or difficulty falling sleeping were not identified.

CONCLUSIONS

Participants with higher concentrations of very long-chain n-3 PUFAs were less likely to have long sleep duration. While objective biomarkers reduce recall bias and misclassification, the cross-sectional design limits assessment of the temporal nature of this relation. These novel findings across 12 cohorts highlight the need for experimental and biological assessments of very long-chain n-3 PUFAs and sleep duration.

Principles of brain aging: Status and challenges of modeling human molecular changes in mice

Due to the extension of human life expectancy, the prevalence of cognitive impairment is rising in the older portion of society. Developing new strategies to delay or attenuate cognitive decline is vital. For this purpose, it is imperative to understand the cellular and molecular events at the basis of brain aging. While several organs are directly accessible to molecular analysis through biopsies, the brain constitutes a notable exception. Most of the molecular studies are performed on postmortem tissues, where cell death and tissue damage have already occurred. Hence, the study of the molecular aspects of cognitive decline largely relies on animal models and in particular on small mammals such as mice. What have we learned from these models? Do these animals recapitulate the changes observed in humans? What should we expect from future mouse studies? In this review we answer these questions by summarizing the state of the research that has addressed cognitive decline in mice from several perspectives, including genetic manipulation and omics strategies. We conclude that, while extremely valuable, mouse models have limitations that can be addressed by the optimal design of future studies and by ensuring that results are cross-validated in the human context.

Role of sleep deprivation in immune-related disease risk and outcomes

Modern societies are experiencing an increasing trend of reduced sleep duration, with nocturnal sleeping time below the recommended ranges for health. Epidemiological and laboratory studies have demonstrated detrimental effects of sleep deprivation on health. Sleep exerts an immune-supportive function, promoting host defense against infection and inflammatory insults. Sleep deprivation has been associated with alterations of innate and adaptive immune parameters, leading to a chronic inflammatory state and an increased risk for infectious/inflammatory pathologies, including cardiometabolic, neoplastic, autoimmune and neurodegenerative diseases. Here, we review recent advancements on the immune responses to sleep deprivation as evidenced by experimental and epidemiological studies, the pathophysiology, and the role for the sleep deprivation-induced immune changes in increasing the risk for chronic diseases. Gaps in knowledge and methodological pitfalls still remain. Further understanding of the causal relationship between sleep deprivation and immune deregulation would help to identify individuals at risk for disease and to prevent adverse health outcomes.

Biochemical and Structural Characteristics, Gene Regulation, Physiological, Pathological and Clinical Features of Lipocalin-Type Prostaglandin D2 Synthase as a Multifunctional Lipocalin

Lipocalin-type prostaglandin (PG) D₂ synthase (L-PGDS) catalyzes the isomerization of PGH₂, a common precursor of the two series of PGs, to produce PGD₂. PGD₂ stimulates three distinct types of G protein-coupled receptors: (1) D type of prostanoid (DP) receptors involved in the regulation of sleep, pain, food intake, and others; (2) chemoattractant receptor-homologous molecule expressed on T helper type 2 cells (CRTH2) receptors, in myelination of peripheral nervous system, adipocyte differentiation, inhibition of hair follicle neogenesis, and others; and (3) F type of prostanoid (FP) receptors, in dexamethasone-induced cardioprotection. L-PGDS is the same protein as β-trace, a major protein in human cerebrospinal fluid (CSF). L-PGDS exists in the central nervous system and male genital organs of various mammals, and human heart; and is secreted into the CSF, seminal plasma, and plasma, respectively. L-PGDS binds retinoic acids and retinal with high affinities (Kd < 100 nM) and diverse small lipophilic substances, such as thyroids, gangliosides, bilirubin and biliverdin, heme, NAD(P)H, and PGD₂, acting as an extracellular carrier of these substances. L-PGDS also binds amyloid β peptides, prevents their fibril formation, and disaggregates amyloid β fibrils, acting as a major amyloid β chaperone in human CSF. Here, I summarize the recent progress of the research on PGD₂ and L-PGDS, in terms of its “molecular properties,” “cell culture studies,” “animal experiments,” and “clinical studies,” all of which should help to understand the pathophysiological role of L-PGDS and inspire the future research of this multifunctional lipocalin.

The metabolic roots of senescence: mechanisms and opportunities for intervention

Cellular senescence entails a permanent proliferative arrest, coupled to multiple phenotypic changes. Among these changes is the release of numerous biologically active molecules collectively known as the senescence-associated secretory phenotype, or SASP. A growing body of literature indicates that both senescence and the SASP are sensitive to cellular and organismal metabolic states, which in turn can drive phenotypes associated with metabolic dysfunction. Here, we review the current literature linking senescence and metabolism, with an eye toward findings at the cellular level, including both metabolic inducers of senescence and alterations in cellular metabolism associated with senescence. Additionally, we consider how interventions that target either metabolism or senescent cells might influence each other and mitigate some of the pro-aging effects of cellular senescence. We conclude that the most effective interventions will likely break a degenerative feedback cycle by which cellular senescence promotes metabolic diseases, which in turn promote senescence.

Substrate-induced product-release mechanism of lipocalin-type prostaglandin D synthase

Prostaglandin D₂ (PGD₂), an endogenous somnogen, is a unique PG that is secreted into the cerebrospinal fluid. PGD₂ is a relatively fragile molecule and should be transported to receptors localized in the basal forebrain without degradation. However, it remains unclear how PGD₂ is stably carried to such remote receptors. Here, we demonstrate that the PGD₂-synthesizing enzyme, Lipocalin-type prostaglandin D synthase (L-PGDS), binds not only its substrate PGH₂ but also its product PGD₂ at two distinct binding sites for both ligands. This behaviour implys its PGD₂ carrier function. Nevertheless, since the high affinity (K_d = ∼0.6 μM) of PGD₂ in the catalytic binding site is comparable to that of PGH₂, it may act as a competitive inhibitor, while our binding assay exhibits only weak inhibition (K_i = 189 μM) of the catalytic reaction. To clarify this enigmatic behavior, we determined the solution structure of L-PGDS bound to one substrate analog by NMR and compared it with the two structures: one in the apo form and the other in substrate analogue complex with 1:2 stoichiometry. The structural comparisons showed clearly that open or closed forms of loops at the entrance of ligand binding cavity are regulated by substrate binding to two sites, and that the binding to a second non-catalytic binding site, which apparently substrate concentration dependent, induces opening of the cavity that releases the product. From these results, we propose that L-PGDS is a unique enzyme having a carrier function and a substrate-induced product-release mechanism.

A CRISPR-Cas9-engineered mouse model for GPI-anchor deficiency mirrors human phenotypes and exhibits hippocampal synaptic dysfunctions

Inherited GPI-anchor biosynthesis deficiencies (IGDs) explain many cases of syndromic intellectual disability. Although diagnostic methods are improving, the pathophysiology underlying the disease remains unclear. Furthermore, we lack rodent models suitable for characterizing cognitive and social disabilities. To address this issue, we generated a viable mouse model for an IGD that mirrors the condition in human patients with a behavioral phenotype and susceptibility to epilepsy. Using this model, we obtained neurological insights such as deficits in synaptic transmission that will facilitate understanding of the pathophysiology of IGDs.

Pathogenic germline mutations in PIGV lead to glycosylphosphatidylinositol biosynthesis deficiency (GPIBD). Individuals with pathogenic biallelic mutations in genes of the glycosylphosphatidylinositol (GPI)-anchor pathway exhibit cognitive impairments, motor delay, and often epilepsy. Thus far, the pathophysiology underlying the disease remains unclear, and suitable rodent models that mirror all symptoms observed in human patients have not been available. Therefore, we used CRISPR-Cas9 to introduce the most prevalent hypomorphic missense mutation in European patients, Pigv:c.1022C > A (p.A341E), at a site that is conserved in mice. Mirroring the human pathology, mutant Pigv^341E mice exhibited deficits in motor coordination, cognitive impairments, and alterations in sociability and sleep patterns, as well as increased seizure susceptibility. Furthermore, immunohistochemistry revealed reduced synaptophysin immunoreactivity in Pigv^341E mice, and electrophysiology recordings showed decreased hippocampal synaptic transmission that could underlie impaired memory formation. In single-cell RNA sequencing, Pigv^341E-hippocampal cells exhibited changes in gene expression, most prominently in a subtype of microglia and subicular neurons. A significant reduction in Abl1 transcript levels in several cell clusters suggested a link to the signaling pathway of GPI-anchored ephrins. We also observed elevated levels of Hdc transcripts, which might affect histamine metabolism with consequences for circadian rhythm. This mouse model will not only open the doors to further investigation into the pathophysiology of GPIBD, but will also deepen our understanding of the role of GPI-anchor–related pathways in brain development.

Lipocalin-type prostaglandin D synthase levels increase in patients with narcolepsy and idiopathic hypersomnia

STUDY OBJECTIVES

Excessive daytime sleepiness (EDS) is a frequent cause for consultation and a defining symptom of narcolepsy and idiopathic hypersomnia (IH). The associated mechanisms remain unclear. Lipocalin-type prostaglandin D synthase (LPGDS) is a plausible sleep-inducing candidate. This study is to compare cerebral spinal fluid (CSF) and serum LPGDS levels in patients group with hypersomnia of central origin, including those with narcolepsy type 1 (NT1) and type 2 (NT2) and IH, to those in healthy controls (Con).

METHODS

Serum LPGDS, CSF LPGDS, and CSF hypocretin-1(Hcrt-1) levels were measured by ELISA in 122 narcolepsy patients (106 NT1 and 16 NT2), 27 IH, and 51Con.

RESULTS

LPGDS levels in CSF (p = 0.02) and serum (p < 0.001) were 22%-25% lower in control subjects than in patients with EDS complaints, including NT1, NT2, and IH. In contrast to significant differences in CSF Hcrt-1 levels, CSF L-PGDS levels and serum L-PGDS were comparable among NT1, NT2, and IH (p > 0.05), except for slightly lower serum LPGDS in IH than in NT1 (p = 0.01). Serum L-PGDS correlated modestly and negatively to sleep latency on MSLT (r = -0.227, p = 0.007) in hypersomnia subjects.

CONCLUSIONS

As a somnogen-producing enzyme, CSF/serum LPGDS may serve as a new biomarker for EDS of central origin and imply a common pathogenetic association, but would complement rather than replaces orexin markers.

Sleep, Narcolepsy, and Sodium Oxybate

Sodium oxybate (SO) has been in use for many decades to treat narcolepsy with cataplexy. It functions as a weak GABAB agonist but also as an energy source for the brain as a result of its metabolism to succinate and as a powerful antioxidant because of its capacity to induce the formation of NADPH. Its actions at thalamic GABAB receptors can induce slow-wave activity, while its actions at GABAB receptors on monoaminergic neurons can induce or delay REM sleep. By altering the balance between monoaminergic and cholinergic neuronal activity, SO uniquely can induce and prevent cataplexy. The formation of NADPH may enhance sleep’s restorative process by accelerating the removal of the reactive oxygen species (ROS), which accumulate during wakefulness. SO improves alertness in normal subjects and in patients with narcolepsy. SO may allay severe psychological stress - an inflammatory state triggered by increased levels of ROS and characterized by cholinergic supersensitivity and monoaminergic deficiency. SO may be able to eliminate the inflammatory state and correct the cholinergic/ monoaminergic imbalance.

Beneficial effects of melatonin on prostanoids pathways in pulmonary hypertensive neonates

Pulmonary arterial hypertension of the newborn (PAHN) is a syndrome caused by chronic hypoxia, characterized by decreased vasodilator function, a marked vasoconstrictor activity, proliferation of smooth muscle cells (SMC) and thickening of the extracellular matrix in the pulmonary circulation, among other characteristics. Prostaglandins are derived from the arachidonic acid (AA) metabolism and are important regulators of pulmonary vascular tone. Since hypoxia induces oxidative stress and has been related to PAHN, a postnatal treatment with melatonin has been proposed due to its antioxidant properties. Here, we determined the effects of melatonin on pulmonary vascular homeostasis given by prostanoids. Ten PAHN newborn lambs were divided in two groups and treated either with vehicle or melatonin. After 1 week of treatment, we assessed pulmonary vascular prostanoids function and expression by wire myography, RT-PCR, Western Blot and immunohistochemistry. Melatonin improved in vivo and ex vivo pulmonary vasodilation. This was associated with an increased function and expression of vasodilator prostanoids at the expense of vasoconstrictor prostanoids. Our study demonstrates for the first time that melatonin may enhance the vasodilator prostanoid pathway in PAHN.

Central Neural Circuits Orchestrating Thermogenesis, Sleep-Wakefulness States and General Anesthesia States

Great progress has been made in specifically identifying the central neural circuits (CNCs) of the core body temperature (Tcore), sleep-wakefulness states (SWs), and general anesthesia states (GAs), mainly utilizing optogenetic or chemogenetic manipulations. We summarize the neuronal populations and neural pathways of these three CNCs, which gives evidence for the orchestration within these three CNCs, and the integrative regulation of these three CNCs by different environmental light signals. We also outline some transient receptor potential (TRP) channels that function in the CNCs-Tcore and are modulated by some general anesthetics, which makes TRP channels possible targets for addressing the general-anesthetics-induced-hypothermia (GAIH). We suggest this review will provide new orientations for further consummating these CNCs and elucidating the central mechanisms of GAIH.

Multitargeting the sleep-pain interaction with pharmacological approaches: A narrative review with suggestions on new avenues of investigation

The multimorbidity formed by sleep disturbances and pain conditions is highly prevalent and has a significant impact in global health and in the socioeconomic system. Although different approaches have been directed toward its management, evidence regarding an optimal treatment is lacking, and pharmacological options are often preferred. Health professionals (e.g., pain and sleep clinicians) tend to focus on their respective expertise, targeting a single symptom with a single drug. This may increase polypharmacy and the risk of drug interactions, adverse events, and mortality. Hence, the use of medications that can directly or indirectly improve sleep, pain, and other possible accompanying conditions without exacerbating them becomes especially relevant. The objectives of this comprehensive review are to: a) describe the beneficial or deleterious effects that some commonly used medications to manage pain have on sleep and sleep disorders; and b) describe the beneficial or deleterious effects that frequently prescribed medications for sleep may have on pain. Moreover, medications targeting some specific sleep-pain interactions will be suggested and future directions for improving sleep and alleviating pain of these patients will be provided with clinical and research perspectives.