A sleep-inducing gene, nemuri, links sleep and immune function in Drosophila

Dreaming of Better Treatments: Advances in Drug Development for Sleep Medicine and Chronotherapy

Throughout history, the development of new sleep medicines has been driven by progress in our understanding of the mechanisms underlying sleep. Ancient civilisations used their understanding of the sedative nature of natural herbs and compounds to induce sleep. The discovery of barbiturates and bromides heralded a new era of synthetic sleep medicine in the 19th century. This was followed by the development of benzodiazepines that were used to inhibit signalling throughout the brain by promoting gamma-amino butyric acid release and thereby produce loss of consciousness. As our understanding of sleep has deepened, newer therapies have more specifically targeted the wake-inducing neurotransmitter orexin with fewer side effects. Given the newly highlighted role of kinases in sleep/wake regulation, we predict that the next breakthroughs in sleep medicine will likely target these kinases. Given the fundamental role that sleep plays in maintaining brain health through processes such as glymphatic clearance, sleep medicine has therapeutic potential beyond just sleep. Recent evidence suggests that sleep disruptions directly contribute to the build-up of pathological neuronal proteins in neurodegenerative disorders. Therefore, sleep medicine could improve prognosis in disorders such as these. Great attention must be paid to the mechanism of action of each sleep medicine, however, as sleep medicines which do not fully mimic sleep could actually worsen disease progression.

Antimicrobial peptides: from discovery to developmental applications

Antimicrobial resistance (AMR) has emerged as a significant crisis in global health. Due to their advantageous properties, antimicrobial peptides (AMPs) have garnered considerable attention as a potential alternative therapy to address the AMR crisis. These peptides might disrupt cell membranes or cell walls to exhibit antimicrobial activity, or modulate the immune response to promote recovery from diseases. In recent years, significant progress has been made in the research of AMPs, alongside the emergence of new challenges. This review first systematically summarizes and critically discusses recent advancements in understanding the characteristics and current landscapes of AMPs, as well as their regulatory mechanisms of action and practical applications, particularly those reported or approved within the last 5 years. Additionally, the principles, paths for their identification, and future research trends in AMPs are also analyzed following a discussion of the advantages and disadvantages of AMPs in comparison to conventional antibiotics. Unlike significant prior literature in this field, this report has summarized the latest major discovery methods for AMPs and, more importantly, emphasized their practical applications by supporting various viewpoints using selected examples of AMPs' applications in real-life scenarios. Besides, some emerging hot topics of AMPs, including those derived from gut microbiota and their potential synergistic effects in combating AMR, were profiled. All of these indicate the originality of the report and provide valuable references for future AMP discoveries and applications.

Glucose uptake in pigment glia suppresses Tau-induced inflammation and photoreceptor degeneration

Brain inflammation contributes to the pathogenesis of neurodegenerative diseases, such as Alzheimer's disease (AD). Glucose hypometabolism and glial activation are pathological features seen in AD brains; however, the connection between the two is not fully understood. Using a Drosophila model of AD, we identified that glucose metabolism in glia plays a critical role in neuroinflammation under disease conditions. Expression of human MATP (hereafter referred to as Tau) in the retinal cells, including photoreceptor neurons and pigment glia, causes photoreceptor degeneration accompanied by the formation of dark-stained round inclusion-like structures and swelling of the lamina cortex. We found that inclusion-like structures are formed by glial phagocytosis, and swelling of the laminal cortex correlates with the expression of antimicrobial peptides. Coexpression of human glucose transporter 3 (SLC2A3, hereafter referred to as GLUT3) with Tau in the retina does not affect Tau levels but suppresses these inflammatory responses and photoreceptor degeneration. We also found that expression of GLUT3, specifically in the pigment glia, is sufficient to suppress inflammatory phenotypes and mitigate photoreceptor degeneration in the Tau-expressing retina. Our results suggest that glial glucose metabolism contributes to inflammatory responses and neurodegeneration in tauopathy.

A knock-in translational reporter for NLP-29 reveals AMP secretion to the apical extracellular matrices following epidermal damage in Caenorhabditis elegans

Antimicrobial peptides (AMPs) are small proteins produced and secreted as part of the innate immune response to infection and wounding. They target pathogens and can also function as signalling molecules, for example, promoting sleep in response to injury in C. elegans . A transcriptional reporter transgene for nlp-29 has been pivotal in studying AMP gene expression and regulation, but to understand AMPs antimicrobial and signalling roles, protein expression and trafficking needs to be monitored. We have now created a knock-in translational reporter allele for nlp-29 , with NLP-29 fused to mKate2, that enables visualisation of this secreted AMP. Using the NLP-29::mKate2 reporter, we demonstrate that NLP-29 is secreted into the cuticle upon genetic or physical cuticle damage. NLP-29::mKate2 will therefore be a valuable tool for visualising the secretion of this peptide in C. elegans and thus to dissect the different roles of this key AMP.

FlyVISTA, an integrated machine learning platform for deep phenotyping of sleep in Drosophila

There is great interest in using genetically tractable organisms such as Drosophila to gain insights into the regulation and function of sleep. However, sleep phenotyping in Drosophila has largely relied on simple measures of locomotor inactivity. Here, we present FlyVISTA, a machine learning platform to perform deep phenotyping of sleep in flies. This platform comprises a high-resolution closed-loop video imaging system, coupled with a deep learning network to annotate 35 body parts, and a computational pipeline to extract behaviors from high-dimensional data. FlyVISTA reveals the distinct spatiotemporal dynamics of sleep and wake-associated microbehaviors at baseline, following administration of the sleep-inducing drug gaboxadol, and with dorsal fan-shaped body drivers. We identify a microbehavior ("haltere switch") exclusively seen during quiescence that indicates a deeper sleep stage. These results enable the rigorous analysis of sleep in Drosophila and set the stage for computational analyses of microbehaviors in quiescent animals.

Glia: the cellular glue that binds circadian rhythms and sleep

Glia are increasingly appreciated as serving an important function in the control of sleep and circadian rhythms. Glial cells in Drosophila and mammals regulate daily rhythms of locomotor activity and sleep as well as homeostatic rebound following sleep deprivation. In addition, they contribute to proposed functions of sleep, with different functions mapping to varied glial subtypes. Here, we discuss recent findings in Drosophila and rodent models establishing a role of glia in circadian or sleep regulation of synaptic plasticity, brain metabolism, removal of cellular debris, and immune challenges. These findings underscore the relevance of glia for benefits attributed to sleep and have implications for understanding the neurobiological mechanisms underlying sleep and associated disorders.

Supplementation of essential amino acids suppresses age-associated sleep loss and sleep fragmentation but not loss of rhythm strength under yeast-restricted malnutrition in Drosophila

Sleep quality and quantity decrease with age, and sleep disturbance increases the risk of many age-associated diseases. There is a significant relationship between nutritional status and sleep outcomes, with malnutrition inducing poor sleep quality in older adults. However, it remains elusive whether, and if so how, nutritional supplementation prevents age-associated sleep problems. Here, we utilized Drosophila to investigate the effects of a malnutrition diet with restricted yeast, a primary protein source, and supplementation of 10 essential amino acids (EAAs) on sleep profiles during ageing. Compared with the standard diet containing 2.7% yeast, the malnutrition diet containing 0.27% yeast significantly decreased target of rapamycin (TOR) signalling and shortened the lifespan of male Canton-S flies. By contrast, age-associated sleep loss, sleep fragmentation and loss of rhythm strength were similarly observed under both diets. Supplementation of the malnutrition diet with EAAs in restricted yeast significantly ameliorated age-associated sleep loss and sleep fragmentation without altering loss of rhythm strength. It also rescued decreased TOR signalling activity but not the shortened lifespan, suggesting that the effects of EAAs on sleep integrity are independent of TOR activity and lifespan regulation. These results may help to develop dietary interventions that improve age-related sleep problems in humans.

A male-killing Spiroplasma endosymbiont has age-mediated impacts on Drosophila endurance and sleep

Endosymbiotic bacteria have a wide range of impacts on host physiology, behavior, metabolism, endurance, and mobility. Recent work found some endosymbionts also impact host sleep duration and quality. These effects may increase as flies age and endosymbiont titers increase. We tested the hypothesis that Spiroplasma poulsonni MSRO negatively impacts sleep in Drosophila melanogaster, and this in turn impairs fly endurance. In geotaxis climbing assays (a proxy for endurance), we found that MSRO impacted climbing endurance but in an age-dependent manner. Among younger flies, MSRO+ flies slept significantly less during dark periods (measured by a Drosophila Activity Monitoring System) compared to uninfected flies, but older MSRO+ flies did not show significant differences in amount of sleep compared to uninfected flies in the same cohort. While MSRO status impacted both sleep and endurance of hosts, endosymbiont-mediated sleep deprivation did not directly explain decreases in fly endurance. We discuss these results in the context of endosymbiont comparative biology.

Enhanced memory despite severe sleep loss in Drosophila insomniac mutants

Sleep is crucial for cognitive functions and life span across species. While sleep homeostasis and cognitive processes are linked through cellular and synaptic plasticity, the signaling pathways connecting them remain unclear. Here, we show that Drosophila insomniac (inc) short sleep mutants, which lack an adaptor protein for the autism-associated Cullin-3 ubiquitin ligase, exhibited enhanced Pavlovian aversive olfactory learning and memory, unlike other sleep mutants with normal or reduced memory. Through a genetic modifier screen, we found that a mild reduction of Protein Kinase A (PKA) signaling specifically rescued the sleep and longevity phenotypes of inc mutants. However, this reduction further increased their excessive memory and mushroom body overgrowth. Since inc mutants displayed higher PKA signaling, we propose that inc loss-of-function suppresses sleep via increased PKA activity, which also constrains the excessive memory of inc mutants. Our data identify a signaling cascade for balancing sleep and memory functions, and provide a plausible explanation for the sleep phenotypes of inc mutants, suggesting that memory hyperfunction can provoke sleep deficits.

Leger RJ. Latitudinal Clines in Climate and Sleep Patterns Shape Disease Outcomes in Drosophila melanogaster Infected by Metarhizium anisopliae

Major latitudinal clines have been observed in Drosophila melanogaster, a human commensal that originated in tropical Africa and has subsequently dispersed globally to colonize temperate habitats. However, despite the crucial role pathogens play in species distribution, our understanding of how geographical factors influence disease susceptibility remains limited. This investigation explored the effects of latitudinal clines and biomes on disease resistance using the common fly pathogen Metarhizium anisopliae and 43 global Drosophila melanogaster populations. The findings revealed correlations between disease resistance and latitudinal gradients of sleep duration, temperature, and humidity. Although enhanced defenses may be driven by fungal diversity at tropical latitudes, the most disease-resistant tropical males also showed the highest susceptibility to desiccation. This suggests potential trade-offs between abiotic stress resistance, necessary for survival in temperate habitats, and disease resistance. Furthermore, the study uncovered interactions between sex, mating status, sleep, and abiotic stresses, affecting disease resistance. Notably, longer-sleeping males and virgin flies survived infections longer, with additional daytime sleep post-infection being protective, particularly in the most resistant fly lines. These observations support the hypothesis that sleep and disease defense are intertwined traits linked to organismal fitness and subject to joint clinal evolution.

The glial UDP-glycosyltransferase Ugt35b regulates longevity by maintaining lipid homeostasis in Drosophila

Lipid droplets (LDs) are dynamic organelles essential for lipid storage and organismal survival. Studies have highlighted the importance of glial function in brain LD formation during aging; however, the genes and mechanisms involved remain elusive. Here, we found that Ugt35b, a member of the uridine diphosphate (UDP)-glycosyltransferases that catalyze the transfer of glycosyl groups to acceptors, is highly expressed in glia and crucial for Drosophila lifespan. By integrating multiomics data, we demonstrated that glial Ugt35b plays key roles in regulating glycerolipid and glycerophospholipid metabolism in the brain. Notably, we found that Ugt35b and Lsd-2 are co-expressed in glia and confirmed their protein interaction in vivo. Knockdown of Ugt35b significantly reduced LD formation by downregulating Lsd-2 expression, while overexpression of Lsd-2 partially rescued the shortened lifespan in glial Ugt35b RNAi flies. Our findings reveal the crucial role of glial Ugt35b in regulating LD formation to maintain brain lipid homeostasis and support Drosophila lifespan.

A carnitine transporter at the blood-brain barrier modulates sleep via glial lipid metabolism in Drosophila

To regulate brain function, peripheral compounds must traverse the blood-brain barrier (BBB), an interface between the brain and the circulatory system. To determine whether specific transport mechanisms are relevant for sleep, we conducted a BBB-specific inducible RNAi knockdown (iKD) screen for genes affecting sleep in Drosophila. We observed reduced sleep with knockdown of solute carrier CG6126, a carnitine transporter, as determined by isotope flux. Our findings suggest that CG6126 regulation of sleep is through the role of the carnitine shuttle in regulating fatty acid metabolism as lipid droplets accumulate in the brains of CG6126 BBB iKD flies. Knocking down mitochondrial carnitine transferases in non-BBB glial cells mimicked the reduced sleep of the CG6126 BBB iKD flies, while bypassing the necessity of carnitine transport with dietary medium-chain fatty acids or palmitoylcarnitine rescued sleep. We propose that carnitine transport via CG6126 promotes brain fatty acid metabolism necessary for maintaining sleep.

A nonsecretory antimicrobial peptide mediates inflammatory organ damage in Drosophila renal tubules

An excessive immune response damages organs, yet its molecular mechanism is incompletely understood. Here, we screened a factor mediating organ damage upon genetic activation of the innate immune pathway using Drosophila renal tubules. We found that an antimicrobial peptide, Attacin-D (AttD), causes organ damage upon immune deficiency (Imd) pathway activation in the Malpighian tubules. Loss of AttD function suppresses most of the pathological phenotypes induced by Imd activation, such as cell death, bloating of the whole animal, and mortality, without compromising the immune activation. AttD is required for the immune-induced damage specifically in the Malpighian tubules and not the midgut. Unlike other antimicrobial peptides, AttD lacks a signal peptide and stays inside tubular cells, potentially damaging the tubular cells via aggregation and oligomerization. Suppression of AttD almost completely attenuates the pathology caused by a gut-tumor-induced immune activation. Our study elucidates the mechanistic effector of immune-induced organ damage.

Non-Immune Functions of Innate Immunity Acting on Physiological Processes: Insights from Drosophila

As the first line of host immune defense, innate immunity plays a key role in warding off foreign pathogens and damage. Drosophila melanogaster, as a classical model animal for more than 100 years, is an important research model for studying innate immunity. In recent years, scientists have made remarkable progress in the recognition mechanisms of innate immunity, the mechanisms of effector molecules, and the modes of their response at the cellular and tissue levels. However, the interaction between innate immunity and other physiological functions remains relatively novel and has yet to be systematically explored. Here, we first briefly discuss the link between the innate immunity system and physiological regulation, from several representative perspectives such as sleep, insulin, and brain function. Then, using Drosophila as a model, we provide an overview of the physiological system and specifically summarize the research on the regulation of physiology by innate immunity, covering sleep, lipid metabolism, development, neurodegenerative diseases, memory, feeding, lifespan, movement, and antioxidation. This review provides valuable perspectives into how innate immunity influences other physiological processes, providing a deeper understanding of the complex roles underlying innate immunity.

Circadian rhythm and immunity: decoding chrono-immunology using the model organism Drosophila melanogaster

Circadian rhythms are important cellular pathways first described for their essential role in helping organisms adjust to the 24 h day-night cycle and synchronize physiological and behavioral functions. Most organisms have evolved a circadian central clock to anticipate daily environmental changes in light, temperature, and mate availability. It is now understood that multiple clocks exist in organisms to regulate the functions of specific organs. Epidemiological studies in humans reported that disruption of the circadian rhythms caused by sleep deprivation is linked to the onset of immune-related conditions, suggesting the importance of circadian regulation of immunity. Mechanistic studies to define how circadian clocks and immune responses interact have profound implications for human health. However, elucidating the clocks and their tissue-specific functions has been challenging in mammals. Many studies using simple model organisms such as Drosophila melanogaster have been pioneering in discovering that the clock controls innate immune responses and immune challenges can impact circadian rhythms and/or their outcomes. In this review, we will report genetic studies using the humble fruit fly that identified the existence of reciprocal interactions between the circadian pathway and innate immune signaling, contributing to elucidate mechanisms in the growing field of chrono-immunology.

cGAS-like receptors drive a systemic STING-dependent host response in Drosophila

cGAS-like receptor (cGLR)-stimulator of interferon genes (STING) recently emerged as an important pathway controlling viral infections in invertebrates. However, its exact contribution at the organismal level remains uncharacterized. Here, we use STING::GFP knockin reporter Drosophila flies to document activation of the pathway in vivo. Four tissues strongly respond to injection of the cyclic dinucleotide 3'2'- cyclic guanosine monophosphate-adenosine monophosphate (cGAMP): the central nervous system, midgut, Malpighian tubules, and genital ducts. The pattern of STING::GFP induction in flies injected with 3'2'-cGAMP or infected by two viruses with different tropism suggests that the reporter is induced by a systemic signal produced in virus-infected cells. Accordingly, ectopic expression of cGLR2 in the fat body induces STING signaling in remote tissues and a cGLR1/2-dependent activity is transferred to females during mating. Furthermore, viral infection can alter sleep in a cGLR1/2- and STING-dependent manner. Altogether, our results reveal a contribution of cyclic dinucleotide signaling to a systemic host response to viral infection in Drosophila.

Orthologs of Drosophila pointed and Arginine kinase 1 impact sleep in mice

Model organisms such as Drosophila are powerful tools to study the genetic basis of sleep. Previously, we identified the genes pointed and Arginine kinase 1 using selective breeding for long and short sleep duration in an outbred population of Drosophila. pointed is a transcription factor that is part of the epidermal growth factor receptor signaling pathway, while Arginine kinase 1 is involved in proline and arginine metabolism. Conserved orthologs of these genes exist in mice, leading us to hypothesize that they would also impact sleep in a murine model. We generated mutations in the murine orthologs Ets1 and Ckm using CRISPR in a C57BL/6N background and used video analysis to measure sleep in the mice. Both mutations affected sleep parameters, and the effects were observed predominantly in female mice, with males showing fewer differences from littermate controls. The study of natural populations in flies therefore leads to candidate genes with functional conservation on sleep in mammals.

Alterations in Circadian Rhythms, Sleep, and Physical Activity in COVID-19: Mechanisms, Interventions, and Lessons for the Future

Although the world is acquitting from the throes of COVID-19 and returning to the regularity of life, its effects on physical and mental health are prominently evident in the post-pandemic era. The pandemic subjected us to inadequate sleep and physical activities, stress, irregular eating patterns, and work hours beyond the regular rest-activity cycle. Thus, perturbing the synchrony of the regular circadian clock functions led to chronic psychiatric and neurological disorders and poor immunological response in several COVID-19 survivors. Understanding the links between the host immune system and viral replication machinery from a clock-infection biology perspective promises novel avenues of intervention. Behavioral improvements in our daily lifestyle can reduce the severity and expedite the convalescent stage of COVID-19 by maintaining consistent eating, sleep, and physical activity schedules. Including dietary supplements and nutraceuticals with prophylactic value aids in combating COVID-19, as their deficiency can lead to a higher risk of infection, vulnerability, and severity of COVID-19. Thus, besides developing therapeutic measures, perpetual healthy practices could also contribute to combating the upcoming pandemics. This review highlights the impact of the COVID-19 pandemic on biological rhythms, sleep-wake cycles, physical activities, and eating patterns and how those disruptions possibly contribute to the response, severity, and outcome of SARS-CoV-2 infection.

Emerging roles of antimicrobial peptides in innate immunity, neuronal function, and neurodegeneration

Antimicrobial peptides (AMPs), a collection of small proteins with important roles in classical innate immunity, have been extensively studied in multiple organisms, particularly in Drosophila melanogaster. Advances in CRISPR/Cas9 genome editing have allowed individual AMP functions to be dissected, revealing specific and selective roles in host defense. Recent findings have also revealed many unexpected contributions of endogenous AMPs to neuronal functions and neurodegenerative diseases, and have shed light on the intersections between innate immunity and neurobiology. We explore the intricate relationships between AMPs and sleep regulation, memory formation, as well as traumatic brain injury and several neurodegenerative diseases such as Alzheimer's disease (AD), frontotemporal dementia (FTD), and Parkinson's disease (PD). Understanding the diverse functions of AMPs opens new avenues for neuroinflammation and neurodegenerative disease research and potential therapeutic development.

Truffle protein and its derived peptides exhibit sleep-promoting effects via regulation of lysosomal autophagy, neurological activity, tyrosine metabolism, and fatty acid elongation

Black truffle (Tuber sinense) is a famous luxurious mushroom with abundant protein resources. Nevertheless, until now, no single study has explored the potential function of black truffle protein in any animal models. Thus, this study investigated the sleep-promoting effects of truffle albumin (TA) and its hydrolysate (TAH). Then, two novel sleep-enhancing peptides were explored from TAH. Our results showed that TA and TAH significantly prolonged the total sleep time and improved sleep quality of insomnia Drosophila. Additionally, two novel peptides YLDLAPL and YLRPEGDW with strong sleep-enhancing activity were explored by virtual screening and Drosophila with transgenic RNA interference (RNAi) technology. Finally, the transcriptomics analysis investigated potential mechanisms of sleep-enhancing effects in Drosophila: (1) regulation of the autophagic activity by altering the lysosomal protein; (2) up-regulation the genes in the pathway of neuroactive ligand-receptor interaction and promotion the function of neurons; (3) promotion the conversion of tyrosine into neurotransmitters; (4) regulation substrate feeding into the tricarboxylic acid (TCA) cycle and promotion free radical scavenging in neuronal cells; (5) promotion the fatty acid elongation and preservation neuronal cells avoid from oxidation.

Targeted single cell expression profiling identifies integrators of sleep and metabolic state

Animals modulate sleep in accordance with their internal and external environments. Metabolic cues are particularly potent regulators of sleep, allowing animals to alter their sleep timing and amount depending on food availability and foraging duration. The fruit fly, Drosophila melanogaster, suppresses sleep in response to acute food deprivation, presumably to forage for food. This process is dependent on a single pair of Lateral Horn Leucokinin (LHLK) neurons, that secrete the neuropeptide Leucokinin. These neurons signal to insulin producing cells and suppress sleep under periods of starvation. The identification of individual neurons that modulate sleep-metabolism interactions provides the opportunity to examine the cellular changes associated with sleep modulation. Here, we use single-cell sequencing of LHLK neurons to examine the transcriptional responses to starvation. We validate that a Patch-seq approach selectively isolates RNA from individual LHLK neurons. Single-cell CEL-Seq comparisons of LHLK neurons between fed and 24-hr starved flies identified 24 genes that are differentially expressed in accordance with starvation state. In total, 12 upregulated genes and 12 downregulated genes were identified. Gene-ontology analysis showed an enrichment for Attacins, a family of anti-microbial peptides, along with several transcripts with diverse roles in regulating cellular function. Targeted knockdown of differentially expressed genes identified multiple genes that function within LHLK neurons to regulate sleep-metabolism interactions. Functionally validated genes include an essential role for the E3 ubiquitin Ligase insomniac, the sorbitol dehydrogenase Sodh1, as well as AttacinC and AttacinB in starvation-induced sleep suppression. Taken together, these findings provide a pipeline for identifying novel regulators of sleep-metabolism interactions within individual neurons.

The NFκB Dif is required for behavioral and molecular correlates of sleep homeostasis in Drosophila

The nuclear factor binding the κ light chain in B-cells (NFκB) is involved in a wide range of cellular processes including development, growth, innate immunity, and sleep. However, genetic studies of the role of specific NFκB transcription factors in sleep have been limited. Drosophila fruit flies carry three genes encoding NFκB transcription factors, Dorsal, Dorsal Immunity Factor (Dif), and Relish. We previously found that loss of the Relish gene from fat body suppressed daily nighttime sleep, and abolished infection-induced sleep. Here we show that Dif regulates daily sleep and recovery sleep following prolonged wakefulness. Mutants of Dif showed reduced daily sleep and suppressed recovery in response to sleep deprivation. Pan-neuronal knockdown of Dif strongly suppressed daily sleep, indicating that in contrast to Relish, Dif functions from the central nervous system to regulate sleep. Based on the unique expression pattern of a Dif- GAL4 driver, we hypothesized that its effects on sleep were mediated by the pars intercerebralis (PI). While RNAi knock-down of Dif in the PI reduced daily sleep, it had no effect on the recovery response to sleep deprivation. However, recovery sleep was suppressed when RNAi knock-down of Dif was distributed across a wider range of neurons. Induction of the nemuri (nur) antimicrobial peptide by sleep deprivation was reduced in Dif mutants and pan-neuronal overexpression of nur also suppressed the Dif mutant phenotype by significantly increasing sleep and reducing nighttime arousability. Together, these findings indicate that Dif functions from brain to target nemuri and to promote deep sleep.

MEDi-SOL: Multi Ensemble Distribution Model for Estimating Sleep Onset Latency

Sleep onset latency (SOL) is an important factor relating to the sleep quality of a subject. Therefore, accurate prediction of SOL is useful to identify individuals at risk of sleep disorders and to improve sleep quality. In this study, we estimate SOL distribution and falling asleep function using an electroencephalogram (EEG), which can measure the electric field of brain activity. We proposed a Multi Ensemble Distribution model for estimating Sleep Onset Latency (MEDi-SOL), consisting of a temporal encoder and a time distribution decoder. We evaluated the performance of the proposed model using a public dataset from the Sleep Heart Health Study. We considered four distributions, Normal, log-Normal, Weibull, and log-Logistic, and compared them with a survival model and a regression model. The temporal encoder with the ensemble log-Logistic and log-Normal distribution showed the best and second-best scores in the concordance index (C-index) and mean absolute error (MAE). Our MEDi-SOL, multi ensemble distribution with combining log-Logistic and log-Normal distribution, shows the best score in C-index and MAE, with a fast training time. Furthermore, our model can visualize the process of falling asleep for individual subjects. As a result, a distribution-based ensemble approach with appropriate distribution is more useful than point estimation.

Associations of maternal sleep trajectories during pregnancy and adverse perinatal outcomes: a prospective cohort study

OBJECTIVE

Sleep problems are common in pregnant women and sleep is altered during pregnancy. However, the associations between sleep trajectory patterns and adverse maternal and neonatal outcomes are unclear. The current study aims to identify sleep trajectory patterns and explore their associations with adverse perinatal outcomes in a prospective cohort study.

METHODS

Pregnant women (N = 232) completed the Pittsburgh Sleep Quality Index each trimester during pregnancy in Tianjin, China. Perinatal outcomes were extracted from the hospital delivery records. Latent class growth analysis (LCGA) described the trajectories of sleep timing, duration, and efficiency. Multivariable linear regression and multivariable logistic regression were employed to evaluate associations between sleep trajectory patterns and perinatal outcomes.

RESULTS

Trajectories were identified for bedtime (early, 49.1%; delaying, 50.9%), wake-up time (early, 82.8% of the sample; late, 17.2%), duration (short, 5.2%; adequate 78.0%; excessive, 16.8%), and efficiency (high, 88.4%; decreasing, 11.6%). Compared with women in more optimal sleep groups, those in the late wake-up, excessive duration, and decreasing efficiency groups had babies with shorter birth lengths (β range, -0.50 to -0.28, p < 0.05). Moreover, women in the decreasing efficiency group had babies with lower birth weight (β, -0.44; p < 0.05). Women in the delaying bedtime group had greater odds of preterm delivery (OR, 4.57; p < 0.05), while those in the decreasing efficiency group had greater odds of cesarean section (OR, 3.12; p < 0.05).

CONCLUSIONS

Less optimal sleep trajectory patterns during pregnancy are associated with perinatal outcomes. Therefore, early assessment of maternal sleep during pregnancy is significant for identifying at-risk women and initiating interventions to reduce perinatal outcomes.

Caenorhabditis elegans neuropeptide NLP-27 enhances neurodegeneration and paralysis in an opioid-like manner during fungal infection

The nervous system of metazoans is involved in host-pathogen interactions to control immune activation. In Caenorhabditis elegans, this includes sleep induction, mediated by neuropeptide-like proteins (NLPs), which increases the chance of survival after wounding. Here we analyzed the role of NLP-27 in the infection of C. elegans with the nematode-trapping fungus Arthrobotrys flagrans. Early responses of C. elegans were the upregulation of nlp-27, the induction of paralysis (sleep), and neurodegeneration of the mechanosensing PVD (Posterior Ventral Process D) neurons. Deletion of nlp-27 reduced neurodegeneration during fungal attack. Induction of nlp-27 was independent of the MAP kinase PMK-1, and expression of nlp-27 in the hypodermis was sufficient to induce paralysis, although NLP-27 was also upregulated in head neurons. NLP-27 contains the pentapeptide YGGYG sequence known to bind the human μ- and κ-type opioid receptors suggesting NLP-27 or peptides thereof act on opioid receptors. The opioid receptor antagonist naloxone shortened the paralysis time like overexpression of NLP-27.

Lifestyle and eating habits changes among adults during COVID-19 era in Egypt: a population-based study

BACKGROUND

The 2019 recent Coronavirus is without a doubt one of the most complicated viruses to ever pose a threat to humanity. Numerous viral containment strategies forced sedentary behaviors and dietary changes that would-otherwise- increase the chances of acquiring non-communicable diseases.

OBJECTIVES

The objectives of the current study are to identify any changes in eating behaviors through the Mediterranean Diet Adherence in a sample of Egyptians throughout the COVID-19 era.

METHODS

A cross-sectional study was done on a sample of 205 Egyptians by an online self-administered questionnaire. The questionnaire included socio-demographic factors, self-reported weights and heights, a validated Arabic form of the well-known International Physical Activity Questionnaire Short Form (IPAQ-SF), a validated Arabic version of 14-items Mediterranean Diet Adherence Screener (MEDAS), in addition to a section assessing dietetic changes. The data was then analyzed using the SPSS version 20 (Statistical Package for Social Sciences).

RESULTS

The majority of the study sample were females (74.6%); had a high level of education (93.2%); and about 75% were married. Most of the participants were non-smokers, with around a 7% increased frequency of smoking after the COVID-19 pandemic. Fast food consumption was also reported by a major percentage of study participants (60%). Low Mediterranean Diet Adherence was found in 52.7%. Moreover, Physical Activity (PA) decreased to 61%. Moreover, there was a statistically significant increase seen in the participants' BMI as well as the number of sleeping hours (p = 0.001 and 0.043 respectively) after the pandemic. Both changed hunger sensation and any changes in physical activity were significantly associated with increased BMI (p < 0.001).

CONCLUSION AND RECOMMENDATIONS

A substantial proportion of the participants showed unhealthy changes in their dietary habits as well as physical activity. Consequently, this calls for urgent public health policies and interventions to guard against the consequences of such unhealthy behaviors.

A Review of the Common Neurodegenerative Disorders: Current Therapeutic Approaches and the Potential Role of Bioactive Peptides

Neurodegenerative disorders, which include Alzheimer's disease (AD), Parkinson's disease (PD), Huntington's disease (HD), and amyotrophic lateral sclerosis (ALS), represent a significant and growing global health challenge. Current therapies predominantly focus on symptom management rather than altering disease progression. In this review, we discuss the major therapeutic strategies in practice for these disorders, highlighting their limitations. For AD, the mainstay treatments are cholinesterase inhibitors and N-methyl-D-aspartate (NMDA) receptor antagonists. For PD, dopamine replacement therapies, including levodopa, are commonly used. HD is managed primarily with symptomatic treatments, and reusable extends survival in ALS. However, none of these therapies halts or substantially slows the neurodegenerative process. In contrast, this review highlights emerging research into bioactive peptides as potential therapeutic agents. These naturally occurring or synthetically designed molecules can interact with specific cellular targets, potentially modulating disease processes. Preclinical studies suggest that bioactive peptides may mitigate oxidative stress, inflammation, and protein misfolding, which are common pathological features in neurodegenerative diseases. Clinical trials using bioactive peptides for neurodegeneration are limited but show promising initial results. For instance, hemiacetal, a γ-secretase inhibitor peptide, has shown potential in AD by reducing amyloid-beta production, though its development was discontinued due to side effects. Despite these advancements, many challenges remain, including identifying optimal peptides, confirming their mechanisms of action, and overcoming obstacles related to their delivery to the brain. Future research should prioritize the discovery and development of novel bioactive peptides and improve our understanding of their pharmacokinetics and pharmacodynamics. Ultimately, this approach may lead to more effective therapies for neurodegenerative disorders, moving beyond symptom management to potentially modify the course of these devastating diseases.

Tripping on the edge of consciousness

Herein the major accomplishments, trials and tribulations, and epiphanies experienced by James M. Krueger over the course of his career in sleep research are presented. They include the characterization of a) the supranormal EEG delta waves occurring during NREMS post sleep loss, b) Factor S as a muramyl peptide, c) the physiological roles of cytokines in sleep regulation, d) multiple other sleep regulatory substances, e) the dramatic changes in sleep over the course of infectious diseases, and f) sleep initiation within small neuronal/glial networks. The theory that the preservation of brain plasticity is the primordial sleep function is briefly discussed. These accomplishments resulted from collaborations with many outstanding scientists including James M. Krueger's mentors (John Pappenheimer and Manfred Karnovsky) and collaborators later in life, including Charles Dinarello, Louis Chedid, Mark Opp, Ferenc Obal jr., Dave Rector, Ping Taishi, Linda Toth, Jeannine Majde, Levente Kapas, Eva Szentirmai, Jidong Fang, Chris Davis, Sandip Roy, Tetsuya Kushikata, Fabio Garcia-Garcia, Ilia Karatsoreos, Mark Zielinski, and Alok De, plus many students, e.g. Jeremy Alt, Kathryn Jewett, Erika English, and Victor Leyva-Grado.

The Drosophila blood-brain barrier regulates sleep via Moody G protein-coupled receptor signaling

Sleep is vital for most animals, yet its mechanism and function remain unclear. We found that permeability of the BBB (blood-brain barrier)-the organ required for the maintenance of homeostatic levels of nutrients, ions, and other molecules in the brain-is modulated by sleep deprivation (SD) and can cell-autonomously effect sleep changes. We observed increased BBB permeability in known sleep mutants as well as in acutely sleep-deprived animals. In addition to molecular tracers, SD-induced BBB changes also increased the penetration of drugs used in the treatment of brain pathologies. After chronic/genetic or acute SD, rebound sleep or administration of the sleeping aid gaboxadol normalized BBB permeability, showing that SD effects on the BBB are reversible. Along with BBB permeability, RNA levels of the BBB master regulator moody are modulated by sleep. Conversely, altering BBB permeability alone through glia-specific modulation of moody, gαo, loco, lachesin, or neuroglian-each a well-studied regulator of BBB function-was sufficient to induce robust sleep phenotypes. These studies demonstrate a tight link between BBB permeability and sleep and indicate a unique role for the BBB in the regulation of sleep.

The NFκB Dif is required for behavioral and molecular correlates of sleep homeostasis in Drosophila

The nuclear factor binding the κ light chain in B-cells (NFκB) is involved in a wide range of cellular processes including development, growth, innate immunity, and sleep. However, efforts have been limited toward understanding how specific NFκB transcription factors function in sleep. Drosophila fruit flies carry three genes encoding NFκB transcription factors, Dorsal, Dorsal Immunity Factor (Dif), and Relish. We previously found that loss of the Relish gene from fat body suppressed daily nighttime sleep, and abolished infection-induced sleep. Here we show that Dif regulates daily sleep and recovery sleep following prolonged wakefulness. Mutants of Dif showed reduced daily sleep and suppressed recovery in response to sleep deprivation. Pan-neuronal knockdown of Dif strongly suppressed daily sleep, indicating that in contrast to Relish, Dif functions from the central nervous system to regulate sleep. Based on the distribution of a Dif-associated GAL4 driver, we hypothesized that its effects on sleep were mediated by the pars intercerebralis (PI). While RNAi knock-down of Dif in the PI reduced daily sleep, it had no effect on the recovery response to sleep deprivation. However, recovery sleep was suppressed when RNAi knock-down of Dif was distributed across a wider range of neurons. Induction of the nemuri (nur) antimicrobial peptide by sleep deprivation was suppressed in Dif mutants and pan-neuronal over-expression of nur also suppressed the Dif mutant phenotype. Together, these findings indicate that Dif functions from brain to target nemuri and to promote sleep.

Sleepiness, not total sleep amount, increases seizure risk

Sleep loss has been associated with increased seizure risk since antiquity. Despite this observation standing the test of time, how poor sleep drives susceptibility to seizures remains unclear. To identify underlying mechanisms, we restricted sleep in Drosophila epilepsy models and developed a method to identify spontaneous seizures using quantitative video tracking. Here we find that sleep loss exacerbates seizures but only when flies experience increased sleep need, or sleepiness , and not necessarily with reduced sleep quantity. This is supported by the paradoxical finding that acute activation of sleep-promoting circuits worsens seizures, because it increases sleep need without changing sleep amount. Sleep-promoting circuits become hyperactive after sleep loss and are associated with increased whole-brain activity. During sleep restriction, optogenetic inhibition of sleep-promoting circuits to reduce sleepiness protects against seizures. Downregulation of the 5HT1A serotonin receptor in sleep-promoting cells mediates the effect of sleep need on seizures, and we identify an FDA-approved 5HT1A agonist to mitigate seizures. Our findings demonstrate that while homeostatic sleep is needed to recoup lost sleep, it comes at the cost of increasing seizure susceptibility. We provide an unexpected perspective on interactions between sleep and seizures, and surprisingly implicate sleep- promoting circuits as a therapeutic target for seizure control.

The antimicrobial peptide database is 20 years old: Recent developments and future directions

In 2023, the Antimicrobial Peptide Database (currently available at https://aps.unmc.edu) is 20-years-old. The timeline for the APD expansion in peptide entries, classification methods, search functions, post-translational modifications, binding targets, and mechanisms of action of antimicrobial peptides (AMPs) has been summarized in our previous Protein Science paper. This article highlights new database additions and findings. To facilitate antimicrobial development to combat drug-resistant pathogens, the APD has been re-annotating the data for antibacterial activity (active, inactive, and uncertain), toxicity (hemolytic and nonhemolytic AMPs), and salt tolerance (salt sensitive and insensitive). Comparison of the respective desired and undesired AMP groups produces new knowledge for peptide design. Our unification of AMPs from the six life kingdoms into "natural AMPs" enabled the first comparison with globular or transmembrane proteins. Due to the dominance of amphipathic helical and disulfide-linked peptides, cysteine, glycine, and lysine in natural AMPs are much more abundant than those in globular proteins. To include peptides predicted by machine learning, a new "predicted" group has been created. Remarkably, the averaged amino acid composition of predicted peptides is located between the lower bound of natural AMPs and the upper bound of synthetic peptides. Synthetic peptides in the current APD, with the highest cationic and hydrophobic amino acid percentages, are mostly designed with varying degrees of optimization. Hence, natural AMPs accumulated in the APD over 20 years have laid the foundation for machine learning prediction. We discuss future directions for peptide discovery. It is anticipated that the APD will continue to play a role in research and education.

Sleep: An Essential and Understudied Process in the Biology of Blood-Feeding Arthropods

Understanding the biology of blood-feeding arthropods is critical to managing them as vectors of etiological agents. Circadian rhythms act in the regulation of behavioral and physiological aspects such as blood feeding, immunity, and reproduction. However, the impact of sleep on these processes has been largely ignored in blood-feeding arthropods, but recent studies in mosquitoes show that sleep-like states directly impact host landing and blood feeding. Our focus in this review is on discussing the relationship between sleep and circadian rhythms in blood-feeding arthropods along with how unique aspects such as blood gluttony and dormancy can impact sleep-like states. We highlight that sleep-like states are likely to have profound impacts on vector-host interactions but will vary between lineages even though few direct studies have been conducted. A myriad of factors, such as artificial light, could directly impact the time and levels of sleep in blood-feeding arthropods and their roles as vectors. Lastly, we discuss underlying factors that make sleep studies in blood-feeding arthropods difficult and how these can be bypassed. As sleep is a critical factor in the fitness of animal systems, a lack of focus on sleep in blood-feeding arthropods represents a significant oversight in understanding their behavior and its role in pathogen transmission.

Beyond the symptom: the biology of fatigue

A workshop titled "Beyond the Symptom: The Biology of Fatigue" was held virtually September 27-28, 2021. It was jointly organized by the Sleep Research Society and the Neurobiology of Fatigue Working Group of the NIH Blueprint Neuroscience Research Program. For access to the presentations and video recordings, see: https://neuroscienceblueprint.nih.gov/about/event/beyond-symptom-biology-fatigue. The goals of this workshop were to bring together clinicians and scientists who use a variety of research approaches to understand fatigue in multiple conditions and to identify key gaps in our understanding of the biology of fatigue. This workshop summary distills key issues discussed in this workshop and provides a list of promising directions for future research on this topic. We do not attempt to provide a comprehensive review of the state of our understanding of fatigue, nor to provide a comprehensive reprise of the many excellent presentations. Rather, our goal is to highlight key advances and to focus on questions and future approaches to answering them.

Entomopathogenic fungal infection following immune gene silencing decreased behavioral and physiological fitness in Aedes aegypti mosquitoes

Entomopathogenic fungi are a promising category of biocontrol agents with mosquitocidal properties. Prior studies have proved their potential to reduce fecundity, human biting and vector competence, all of them together determine vectorial capacity of the mosquitoes. Unfortunately, conventional vector control strategies are inadequate with growing problem of insecticide resistance and environmental deterioration. Therefore, alternate vector control measures are immediately needed and to accomplish that, an improved understanding of behavioral and physiological defense mechanisms of the mosquitoes against fungal infection is essential. In this study, fitness was considered with respect to different behavioral (self-grooming and flight), physiological (antifungal activity and antimicrobial peptides) parameters and survival rates as compared to the control group. We found a significant upregulation in CLSP2, TEP22, Rel1 and Rel2 genes at multiple time periods of fungal infection, which indicates the successful fungal infection and activation of Toll and IMD pathways in mosquitoes. RNAi-mediated silencing of Rel1 and Rel2 genes (transcription factors of Toll and IMD pathways, respectively) significantly reduced the survival, self-grooming frequencies and durations, and flight locomotor activity among adult Ae. aegypti female mosquitoes. Moreover, Rel1 and Rel2 knockdown significantly decreased antifungal activity and antimicrobial peptides expression levels in target mosquitoes. These results indicate an overall decrease in fitness of the mosquitoes after fungal challenge following Rel1 and Rel2 silencing. These findings provide an improved understanding of behavioral and physiological responses in mosquitoes with altered immunity against entomopathogenic fungal infections which can guide us towards the development of novel biocontrol strategies against mosquitoes.

The zebrafish mutant dreammist implicates sodium homeostasis in sleep regulation

Sleep is a nearly universal feature of animal behaviour, yet many of the molecular, genetic, and neuronal substrates that orchestrate sleep/wake transitions lie undiscovered. Employing a viral insertion sleep screen in larval zebrafish, we identified a novel gene, dreammist (dmist), whose loss results in behavioural hyperactivity and reduced sleep at night. The neuronally expressed dmist gene is conserved across vertebrates and encodes a small single-pass transmembrane protein that is structurally similar to the Na+,K+-ATPase regulator, FXYD1/Phospholemman. Disruption of either fxyd1 or atp1a3a, a Na+,K+-ATPase alpha-3 subunit associated with several heritable movement disorders in humans, led to decreased night-time sleep. Since atpa1a3a and dmist mutants have elevated intracellular Na+ levels and non-additive effects on sleep amount at night, we propose that Dmist-dependent enhancement of Na+ pump function modulates neuronal excitability to maintain normal sleep behaviour.

Modulation and neural correlates of postmating sleep plasticity in Drosophila females

Sleep is essential, but animals may forgo sleep to engage in other critical behaviors, such as feeding and reproduction. Previous studies have shown that female flies exhibit decreased sleep after mating, but our understanding of the process is limited. Here, we report that postmating nighttime sleep loss is modulated by diet and sleep deprivation, demonstrating a complex interaction among sleep, reproduction, and diet. We also find that female-specific pC1 neurons and sleep-promoting dorsal fan-shaped body (dFB) neurons are required for postmating sleep plasticity. Activating pC1 neurons leads to sleep suppression on standard fly culture media but has little sleep effect on sucrose-only food. Published connectome data suggest indirect, inhibitory connections among pC1 subtypes. Using calcium imaging, we show that activating the pC1e subtype inhibits dFB neurons. We propose that pC1 and dFB neurons integrate the mating status, food context, and sleep drive to modulate postmating sleep plasticity.

Allnighter pseudokinase-mediated feedback links proteostasis and sleep in Drosophila

In nervous systems, retrograde signals are key for organizing circuit activity and maintaining neuronal homeostasis. We identify the conserved Allnighter (Aln) pseudokinase as a cell non-autonomous regulator of proteostasis responses necessary for normal sleep and structural plasticity of Drosophila photoreceptors. In aln mutants exposed to extended ambient light, proteostasis is dysregulated and photoreceptors develop striking, but reversible, dysmorphology. The aln gene is widely expressed in different neurons, but not photoreceptors. However, secreted Aln protein is retrogradely endocytosed by photoreceptors. Inhibition of photoreceptor synaptic release reduces Aln levels in lamina neurons, consistent with secreted Aln acting in a feedback loop. In addition, aln mutants exhibit reduced night time sleep, providing a molecular link between dysregulated proteostasis and sleep, two characteristics of ageing and neurodegenerative diseases.

Antimicrobial peptides do not directly contribute to aging in Drosophila, but improve lifespan by preventing dysbiosis

Antimicrobial peptides (AMPs) are innate immune effectors first studied for their role in host defence. Recent studies have implicated these peptides in the clearance of aberrant cells and in neurodegenerative syndromes. In Drosophila, many AMPs are produced downstream of Toll and Imd NF-κB pathways upon infection. Upon aging, AMPs are upregulated, drawing attention to these molecules as possible causes of age-associated inflammatory diseases. However, functional studies overexpressing or silencing these genes have been inconclusive. Using an isogenic set of AMP gene deletions, we investigated the net impact of AMPs on aging. Overall, we found no major effect of individual AMPs on lifespan, with the possible exception of Defensin. However, ΔAMP14 flies lacking seven AMP gene families displayed reduced lifespan. Increased bacterial load in the food of aged ΔAMP14 flies suggested that their lifespan reduction was due to microbiome dysbiosis, consistent with a previous study. Moreover, germ-free conditions extended the lifespan of ΔAMP14 flies. Overall, our results did not point to an overt role of individual AMPs in lifespan. Instead, we found that AMPs collectively impact lifespan by preventing dysbiosis during aging.

The Importance of Animal Models in Biomedical Research: Current Insights and Applications

Animal research is considered a key element in advance of biomedical science. Although its use is controversial and raises ethical challenges, the contribution of animal models in medicine is essential for understanding the physiopathology and novel treatment alternatives for several animal and human diseases. Current pandemics’ pathology, such as the 2019 Coronavirus disease, has been studied in primate, rodent, and porcine models to recognize infection routes and develop therapeutic protocols. Worldwide issues such as diabetes, obesity, neurological disorders, pain, rehabilitation medicine, and surgical techniques require studying the process in different animal species before testing them on humans. Due to their relevance, this article aims to discuss the importance of animal models in diverse lines of biomedical research by analyzing the contributions of the various species utilized in science over the past five years about key topics concerning human and animal health.

Unraveling the Role of Antimicrobial Peptides in Insects

Antimicrobial peptides (AMPs) are short, mainly positively charged, amphipathic molecules. AMPs are important effectors of the immune response in insects with a broad spectrum of antibacterial, antifungal, and antiparasitic activity. In addition to these well-known roles, AMPs exhibit many other, often unobvious, functions in the host. They support insects in the elimination of viral infections. AMPs participate in the regulation of brain-controlled processes, e.g., sleep and non-associative learning. By influencing neuronal health, communication, and activity, they can affect the functioning of the insect nervous system. Expansion of the AMP repertoire and loss of their specificity is connected with the aging process and lifespan of insects. Moreover, AMPs take part in maintaining gut homeostasis, regulating the number of endosymbionts as well as reducing the number of foreign microbiota. In turn, the presence of AMPs in insect venom prevents the spread of infection in social insects, where the prey may be a source of pathogens.

Propofol-induced sleep ameliorates cognition impairment in sleep-deprived rats

PURPOSE

Propofol has been shown to clear sleep debt in rats after sleep deprivation (SD). We examined whether or not propofol-assisted sleep can restore cognitive function in SD rats and explored the possible mechanisms.

METHODS

A sleep deprivation model was established by housing 9 to 12 week-old rats to a multiplatform water tank for 96 h. Model rats were then intraperitoneally injected with different concentrations of propofol or 10% fat emulsion (vehicle control). All treatment groups were examined for spatial learning and memory ability in the Morris water maze (MWM). After euthanasia, morphological changes in the hippocampus, hippocampal neurons, and mitochondria were examined by hematoxylin-eosin staining and transmission electron microscopy. Serum and hippocampal levels of IL-1β, TNF-α, and hippocampal concentrations of ATP and Cyt-c were measured by ELISA (enzyme-linked immunosorbent assay). Immunohistochemistry and Western blotting were performed to assess hippocampal expression of Bcl-2, Bax, and cleaved caspase-3.

RESULTS

Results showed that escape latencies in MWM training trials were significantly shorter and target crossings in the memory probe trial significantly greater in propofol-treated SD model rats compared to vehicle-treated SD rats. Propofol also reduced the number of apoptotic bodies in the hippocampal CA1 region. Sleep deprivation reduced IL-1β and ATP in hippocampus while increasing TNF-α and Cyt-c, and propofol treatment reversed all these changes. There was no significant difference in Bcl-2 expression between propofol- and vehicle-treated SD rats, but pro-apoptotic Bax and cleaved caspase-3 expression levels were significantly reduced by propofol in SD rats.

CONCLUSIONS

Propofol-assisted sleep restored cognitive function in SD rats possibly by attenuating mitochondria-mediated neuronal apoptosis in the hippocampus.

The duration of caffeine treatment plays an essential role in its effect on sleep and circadian rhythm

Sleep is regulated by the homeostatic system and the circadian clock. Caffeine intake promotes wakefulness in Drosophila. In humans, caffeine is consumed on a daily basis and hence it is important to understand the effect of prolonged caffeine intake on both circadian and homeostatic regulation of sleep. Furthermore, sleep changes with age and the impact of caffeine on age-dependent sleep fragmentation are yet to be understood. Hence in the present study, we examined the effect of short exposure to caffeine on homeostatic sleep and age-dependent sleep fragmentation in Drosophila. We further assessed the effect of prolonged exposure to caffeine on homeostatic sleep and circadian clock. The results of our study showed that short exposure to caffeine reduces sleep and food intake in mature flies. It also enhances sleep fragmentation with increasing age. However, we have not assessed the effect of caffeine on food intake in older flies. On the other hand, prolonged caffeine exposure did not exert any significant effect on the duration of sleep and food intake in mature flies. Nevertheless, prolonged caffeine ingestion decreased the morning and evening anticipatory activity in these flies indicating that it affects the circadian rhythm. These flies also exhibited phase delay in the clock gene timeless transcript oscillation and exhibited either behavioral arrhythmicity or a longer free-running period under constant darkness. In summary, the results of our studies showed that short exposure to caffeine increases the sleep fragmentation with age whereas prolonged caffeine exposure disrupts the circadian clock.

Integration of genome-scale data identifies candidate sleep regulators

STUDY OBJECTIVES

Genetics impacts sleep, yet, the molecular mechanisms underlying sleep regulation remain elusive. In this study, we built machine learning models to predict sleep genes based on their similarity to genes that are known to regulate sleep.

METHODS

We trained a prediction model on thousands of published datasets, representing circadian, immune, sleep deprivation, and many other processes, using a manually curated list of 109 sleep genes.

RESULTS

Our predictions fit with prior knowledge of sleep regulation and identified key genes and pathways to pursue in follow-up studies. As an example, we focused on the NF-κB pathway and showed that chronic activation of NF-κB in a genetic mouse model impacted the sleep-wake patterns.

CONCLUSION

Our study highlights the power of machine learning in integrating prior knowledge and genome-wide data to study genetic regulation of complex behaviors such as sleep.

Many faces of sleep regulation: beyond the time of day and prior wake time

The two-process model of sleep regulation posits two main processes regulating sleep: the circadian process controlled by the circadian clock and the homeostatic process that depends on the history of sleep and wakefulness. The model has provided a dominant conceptual framework for sleep research since its publication ~ 40 years ago. The time of day and prior wake time are the primary factors affecting the circadian and homeostatic processes, respectively. However, it is critical to consider other factors influencing sleep. Since sleep is incompatible with other behaviors, it is affected by the need for essential behaviors such as eating, foraging, mating, caring for offspring, and avoiding predators. Sleep is also affected by sensory inputs, sickness, increased need for memory consolidation after learning, and other factors. Here, we review multiple factors influencing sleep and discuss recent insights into the mechanisms balancing competing needs.

Advancements, challenges and future perspectives on peptide-based drugs: Focus on antimicrobial peptides

Among other health related issues, the rising concerns on drug resistance led to look for alternative pharmaceutical drugs that are effective both against infectious and noninfectious diseases. Antimicrobial peptides (AMPs) emerged as potential therapeutic molecule with wide range of applications. With their limitations, AMPs have gained reputable attentions in research as well as in the pharmaceutical industry. This review highlighted the historical background, research trends, technological advancements, challenges, and future perspectives in the development and applications of peptide drugs. Some vital questions related with the need for pharmaceutical production, factors for the slow and steady journey, the importance of oral bioavailability, and the drug resistance possibilities of AMPs were raised and addressed accordingly. Therefore, the current study is believed to provide a profound understanding in the past and current scenarios and future directions on the therapeutic impacts of peptide drugs.

Ecdysone acts through cortex glia to regulate sleep in Drosophila

Steroid hormones are attractive candidates for transmitting long-range signals to affect behavior. These lipid-soluble molecules derived from dietary cholesterol easily penetrate the brain and act through nuclear hormone receptors (NHRs) that function as transcription factors. To determine the extent to which NHRs affect sleep:wake cycles, we knocked down each of the 18 highly conserved NHRs found in Drosophila adults and report that the ecdysone receptor (EcR) and its direct downstream NHR Eip75B (E75) act in glia to regulate the rhythm and amount of sleep. Given that ecdysone synthesis genes have little to no expression in the fly brain, ecdysone appears to act as a long-distance signal and our data suggest that it enters the brain more at night. Anti-EcR staining localizes to the cortex glia in the brain and functional screening of glial subtypes revealed that EcR functions in adult cortex glia to affect sleep. Cortex glia are implicated in lipid metabolism, which appears to be relevant for actions of ecdysone as ecdysone treatment mobilizes lipid droplets (LDs), and knockdown of glial EcR results in more LDs. In addition, sleep-promoting effects of exogenous ecdysone are diminished in lsd-2 mutant flies, which are lean and deficient in lipid accumulation. We propose that ecdysone is a systemic secreted factor that modulates sleep by stimulating lipid metabolism in cortex glia.