Phenotypic dysregulation of microglial activation in young offspring rats with maternal sleep deprivation-induced cognitive impairment

Subsequent maternal sleep deprivation aggravates cognitive impairment by modulating hippocampal neuroinflammatory responses and synaptic function in maternal isoflurane-exposed offspring mice

INTRODUCTION

Pregnant women may need to undergo non-obstetric surgery under general anesthesia owing to medical needs, and pregnant women frequently experience sleep disturbances during late gestation. Preclinical studies demonstrated that maternal isoflurane exposure (MISO) or maternal sleep deprivation (MSD) contributed to cognitive impairments in offspring. Research studies in mice have revealed that SD can aggravate isoflurane-induced cognitive deficits. However, it remains unclear whether MSD aggravates MISO-induced cognitive deficits in offspring. The purpose of this research was to explore the combined effects of MSD and MISO on offspring cognitive function and the role of neuroinflammation and synaptic function in the process of MSD + MISO.

METHODS

Pregnant mice were exposed to 1.4% isoflurane by inhalation for 4 h on gestational day (GD) 14. Dams were then subjected to SD for 6 h (12:00-18:00 h) during GD15-21. At 3 months of age, the offspring mice were subjected to the Morris water maze test to assess cognitive function. Then the levels of inflammatory and anti-inflammatory markers and synaptic function-related proteins were assessed using molecular biology methods.

RESULTS

The results of this study demonstrated that MISO led to cognitive dysfunction, an effect that was aggravated by MSD. In addition, MSD exacerbated the maternal isoflurane inhalation, leading to an enhancement in the expression levels of interleukin (IL)-1β, IL-6, and tumor necrosis factor-alpha and a reduction in the hippocampal levels of IL-10, synaptophysin, post-synaptic density-95, growth-associated protein-43, and brain-derived neurotrophic factor.

CONCLUSION

Our findings revealed that MSD aggravated the cognitive deficits induced by MISO in male offspring mice, and these results were associated with neuroinflammation and alternations in synaptic function.

Melatonin improves maternal sleep deprivation-induced learning and memory impairment, inflammation, and synaptic dysfunction in murine male adult offspring

INTRODUCTION

Maternal sleep deprivation (MSD), which induces inflammation and synaptic dysfunction in the hippocampus, has been associated with learning and memory impairment in offspring. Melatonin (Mel) has been shown to have anti-inflammatory, antioxidant, and neuroprotective function. However, the beneficial effect of Mel on MSD-induced cognitive impairment and its mechanisms are unknown.

METHODS

In the present study, adult offspring suffered from MSD were injected with Mel (20 mg/kg) once a day during postnatal days 61-88. The cognitive function was evaluated by the Morris water maze test. Levels of proinflammatory cytokines were examined by enzyme-linked immunosorbent assay. The mRNA and protein levels of synaptic plasticity associated proteins were examined using reverse transcription-polymerase chain reaction and western blotting.

RESULTS

The results showed that MSD impaired learning and memory in the offspring mice. MSD increased the levels of interleukin (IL)-1creIL-6, and tumor necrosis factor-α and decreased the expression levels of brain-derived neurotrophic factor, tyrosine kinase receptor B, postsynaptic density protein-95, and synaptophysin in the hippocampus. Furthermore, Mel attenuated cognitive impairment and restored markers of inflammation and synaptic plasticity to control levels.

CONCLUSIONS

These findings indicated that Mel could ameliorate learning and memory impairment induced by MSD, and these beneficial effects were related to improvement in inflammation and synaptic dysfunction.

Sleep deprivation from mid-gestation leads to impaired of motor coordination in young offspring mice with microglia activation in the cerebellar vermis

OBJECTIVE

To investigate the effects of mid-pregnancy sleep deprivation (SD) in C57BL/6 J mice on the motor coordination of the offspring and to explore the potential mechanism of microglia activation in the cerebellar vermis of the offspring involved in the induction of impaired motor coordination development.

METHODS

C57BL/6 J pregnant mice were randomly divided into the SD and control groups. SD was implemented by the multi-platform method from first day of the middle pregnancy (gestation day 8, GD8). At postnatal day 21 (PND21), we measured the development of motor behavior and collected cerebellar vermis tissues to observe the activation of microglia by H&E staining, the expression of microglia-specific markers ionized calcium-binding adaptor molecule-1 (Iba-1) and cluster of differentiation 68 (CD68) by immunohistochemical, and interleukin-4 (IL-4), interleukin-6 (IL-6), interleukin-10 (IL-10), and tumor necrosis factor -α (TNF-α) by real-time quantitative PCR (RT-qPCR).

RESULTS

In the offspring of SD group, comparing to the control group, the total time of passage and the reverse crawl distance in the balance beam test, and the frequency of falls from the suspension cord was increased; with lower max rotational speed and shorter duration in the rotarod experiment. Further, we found that the microglia of cerebellar vermis tissues emerged an amoeba-like activation. The mean gray value of Iba-1 was lower, the density of positive cells of CD68 and the expression levels of IL-6 and TNF-α were increased.

CONCLUSIONS

The motor coordination of offspring is impaired, accompanying a SD from mid-pregnancy, and the cerebellar vermis showed microglia activation and pro-inflammatory response. It suggested the adverse effects of SD from mid-gestation on the development of motor coordination through the inflammatory response in the cerebellar vermis of the offspring.

Prenatal sleep health and risk of offspring ADHD symptomatology and associated phenotypes: a prospective analysis of timing and sex differences in the ECHO cohort

Background

Sleep difficulties are common in pregnancy, yet poor prenatal sleep may be related to negative long-term outcomes for the offspring, including risk for attention-deficit/hyperactivity disorder (ADHD). Existing studies are few and have not examined timing of exposure effects or offspring sex moderation. We thus aimed to test the hypotheses that poor sleep health in pregnancy is associated with increased risk for ADHD symptoms and offspring sleep problems at approximately 4 years of age.

Methods

Participants were 794 mother-child dyads enrolled in the NIH Environmental Influences on Child Health Outcomes Study (ECHO). Participants self-reported on sleep duration, quality, and disturbances during pregnancy and on children's ADHD symptoms and sleep problems on the Child Behaviour Checklist.

Findings

Pregnant participants were 32.30 ± 5.50 years and children were 46% female. 44 percent of pregnant participants identified as Hispanic or Latine; 49% identified as White. Second-trimester sleep duration was associated with offspring ADHD symptoms (b = -0.35 [95% CI = -0.57, -0.13], p = 0.026), such that shorter duration was associated with greater symptomatology. Poorer sleep quality in the second trimester was also associated with increased ADHD symptomatology (b = 0.66 [95% CI = 0.18, 1.14], p = 0.037). Greater sleep disturbances in the first trimester were associated with offspring ADHD (b = 1.03 [95% CI = 0.32, 1.03], p = 0.037) and in the second trimester with sleep problems (b = 1.53 [95% CI = 0.42, 2.92], p = 0.026). We did not document substantial offspring sex moderation.

Interpretation

Poor prenatal sleep health, particularly quality and duration in the second trimester, may be associated with offspring risk of neurodevelopmental disorders and sleep problems in early childhood. Further research is needed to understand mechanisms, yet our study suggests that prenatal maternal sleep may be a modifiable target for interventions aimed at optimizing early neurodevelopment.

Funding

NIH grants U2COD023375, U24OD023382, U24OD023319, UH3OD023320, UH3OD023305, UH3OD023349, UH3OD023313, UH3OD023272, UH3OD023328, UH3OD023290, K08MH117452 and NARSAD Young Investigator Award 28545.

Microglia and Astroglia-The Potential Role in Neuroinflammation Induced by Pre- and Neonatal Exposure to Lead (Pb)

Neuroinflammation is one of the postulated mechanisms for Pb neurotoxicity. However, the exact molecular mechanisms responsible for its pro-inflammatory effect are not fully elucidated. In this study, we examined the role of glial cells in neuroinflammation induced by Pb exposure. We investigated how microglia, a type of glial cell, responded to the changes caused by perinatal exposure to Pb by measuring the expression of Iba1 at the mRNA and protein levels. To assess the state of microglia, we analyzed the mRNA levels of specific markers associated with the cytotoxic M1 phenotype (Il1b, Il6, and Tnfa) and the cytoprotective M2 phenotype (Arg1, Chi3l1, Mrc1, Fcgr1a, Sphk1, and Tgfb1). Additionally, we measured the concentration of pro-inflammatory cytokines (IL-1β, IL-6, and TNF-α). To assess the reactivity and functionality status of astrocytes, we analyzed the GFAP (mRNA expression and protein concentration) as well as glutamine synthase (GS) protein level and activity. Using an electron microscope, we assessed ultrastructural abnormalities in the examined brain structures (forebrain cortex, cerebellum, and hippocampus). In addition, we measured the mRNA levels of Cxcl1 and Cxcl2, and their receptor, Cxcr2. Our data showed that perinatal exposure to Pb at low doses affected both microglia and astrocyte cells' status (their mobilization, activation, function, and changes in gene expression profile) in a brain-structure-specific manner. The results suggest that both microglia and astrocytes represent a potential target for Pb neurotoxicity, thus being key mediators of neuroinflammation and further neuropathology evoked by Pb poisoning during perinatal brain development.

An enriched environment improves maternal sleep deprivation-induced cognitive deficits and synaptic plasticity via hippocampal histone acetylation

INTRODUCTION

Growing evidence clearly demonstrates that maternal rodents exposure to sleep deprivation (SD) during late pregnancy impairs learning and memory in their offspring. Epigenetic mechanisms, particularly histone acetylation, are known to be involved in synaptic plasticity, learning, and memory. We hypothesize that the cognitive decline induced by SD during late pregnancy is associated with histone acetylation dysfunction, and this effect could be reversed by an enriched environment (EE).

METHODS

In the present study, pregnant CD-1 mice were exposed to SD during the third trimester of pregnancy. After weaning, all offspring were randomly assigned to two subgroups in either a standard environment or an EE. When offspring were 3 months old, the Morris water maze was used to evaluate hippocampal-dependent learning and memory ability. Molecular biological techniques, including western blot and real-time fluorescence quantitative polymerase chain reaction, were used to examine the histone acetylation pathway and synaptic plasticity markers in the hippocampus of offspring.

RESULTS

The results showed that the following were all reversed by EE treatment: maternal SD (MSD)-induced cognitive deficits including spatial learning and memory; histone acetylation dysfunction including increased histone deacetylase 2 (HDAC2) and decreased histone acetyltransferase (CBP), and the acetylation levels of H3K9 and H4K12; synaptic plasticity dysfunction including decreased brain-derived neurotrophic factor; and postsynaptic density protein-95.

CONCLUSIONS

Our findings suggested that MSD could damage learning ability and memory in offspring via the histone acetylation pathway. This effect could be reversed by EE treatment.

Microglia activation mediates circadian rhythm disruption-induced cognitive impairment in mice

Alzheimer's disease (AD) is the leading cause of dementia and there are no effective treatments for this disease currently. Circadian rhythm disruption (CRD) is a hallmark of modern society that appears to be on the rise. It is well reported that AD is associated with disrupted circadian functioning and CRD can impair cognitive function. However, the cellular mechanisms underlying CRD-associated cognitive decline remain elusive. In this study, we investigated whether microglia are involved in CRD-induced cognitive decline. We established experimental 'jet lag' (phase delay of the light/dark cycles)-induced CRD mouse model and observed significant impairment of spatial learning and memory function in these mice. In the brain, CRD resulted in neuroinflammation, which was characterized by microglia activation and increased pro-inflammatory cytokine production, impairments in neurogenesis and reduction of synaptic proteins in the hippocampus. Interestingly, elimination of microglia with the colony stimulating factor-1 receptor inhibitor PLX3397 prevented CRD-induced neuroinflammation, cognitive decline, impairment of neurogenesis and loss of synaptic proteins. These findings collectively suggest that microglia activation plays a key role in CRD-induced cognitive deficit most likely through neuroinflammation-mediated impairments in adult neurogenesis and synapses.

The stress of losing sleep: Sex-specific neurobiological outcomes

Sleep is a vital and evolutionarily conserved process, critical to daily functioning and homeostatic balance. Losing sleep is inherently stressful and leads to numerous detrimental physiological outcomes. Despite sleep disturbances affecting everyone, women and female rodents are often excluded or underrepresented in clinical and pre-clinical studies. Advancing our understanding of the role of biological sex in the responses to sleep loss stands to greatly improve our ability to understand and treat health consequences of insufficient sleep. As such, this review discusses sex differences in response to sleep deprivation, with a focus on the sympathetic nervous system stress response and activation of the hypothalamic-pituitary-adrenal (HPA) axis. We review sex differences in several stress-related consequences of sleep loss, including inflammation, learning and memory deficits, and mood related changes. Focusing on women's health, we discuss the effects of sleep deprivation during the peripartum period. In closing, we present neurobiological mechanisms, including the contribution of sex hormones, orexins, circadian timing systems, and astrocytic neuromodulation, that may underlie potential sex differences in sleep deprivation responses.

Ferroptosis participated in hippocampal neuroinflammation damage of in offspring rats after maternal sleep deprivation

Sleep deprivation during pregnancy has important effects on the pregnant woman herself and her offspring, and some studies have found that neuroinflammation in her offspring is important, but the mechanisms are poorly understood. To investigate the involvement of ferroptosis in cognitive impairment due to hippocampal neuroinflammation in offspring rats after maternal sleep deprivation. SD rats exposed to late gestational sleep deprivation were deprived of sleep for 72 h. Their offspring were given the ferroptosis inhibitor liproxstatin-1 (5 mg/kg) intraperitoneally 3 days after birth. The results showed that MSD resulted in impaired learning memory capacity and significant downregulation of PSD95 and NeuN. Microglia were significantly activated, inflammatory factor expression was increased, the ferroptosis regulatory protein GPX4 was downregulated, ACSL4 was significantly upregulated, and lipid metabolite 4-HNE expression was increased. In contrast, the MSD-induced impairment of inflammation and learning memory capacity in the offspring was ameliorated after treatment with ferroptosis inhibitors. These results suggest that MSD-induced neural damage characterized ferroptosis in the hippocampal region of the offspring rats, leading to a decrease in learning and memory function, which may be related to the decreased levels of Nrf2 and HO-1.

Long-term environmental enrichment overcomes depression, learning, and memory impairment in elderly CD-1 mice with maternal sleep deprivation exposure

Early-life stress disrupts central nervous system development and increases the risk of neuropsychiatric disorder in offspring based on rodent studies. Maternal sleep deprivation (MSD) in rodents has also been associated with depression and cognitive decline in adult offspring. However, it is not known whether these issues persist into old age. Environmental enrichment is a non-pharmacological intervention with proven benefits in improving depression and cognitive impairment; however, it is unclear whether these benefits hold for aging mice following MSD exposure. The aim of this study was to explore the effects of MSD on depression and cognition in elderly offspring CD-1 mice and to determine whether long-term environmental enrichment could alleviate these effects by improving neuroinflammation and synaptic plasticity. The offspring mice subjected to MSD were randomly assigned to either a standard environment or an enriched environment. At 18 months of age, the forced swimming and tail suspension tests were used to evaluated depression-like behaviors, and the Morris water maze test was used to evaluate cognitive function. The expression levels of hippocampal proinflammatory cytokines and synaptic plasticity-associated proteins were also measured. MSD increased depression-like behaviors and impaired cognition function in aging CD-1 offspring mice. These effects were accompanied by upregulated interleukin (IL)-1β, IL-6, and tumor necrosis factor-α expression, and downregulated brain-derived neurotrophic factor, tyrosine kinase receptor B, postsynaptic density-95, and synaptophysin expression in the hippocampus. All of these changes were reversed by long-term exposure to an enriched environment. These findings suggest that MSD exerts long-term effects on the behaviors of offspring in mice, leading to depression and cognitive impairment in older age. Importantly, long-term environmental enrichment could counteract the behavior difficulties induced by MSD through improving hippocampal proinflammatory cytokines and synaptic plasticity-associated proteins.

Early Life Stress, Neuroinflammation, and Psychiatric Illness of Adulthood

Stress exposure during early stages of life elevates the risk of developing psychopathologies and psychiatric illness in later life. The brain and immune system are not completely developed by birth and therefore continue develop after birth; this post birth development is influenced by several psychosocial factors; hence, early life stress (ELS) exposure can alter brain structural development and function. A growing number of experimental animal and observational human studies have investigated the link between ELS exposure and increased risk of psychopathology through alternations in the immune system, by evaluating inflammation biomarkers. Recent studies, including brain imaging, have also shed light on the mechanisms by which both the innate and adaptive immune systems interact with neural circuits and neurotransmitters, which affect psychopathology. Herein, we discuss the link between the experience of stress in early life and lifelong alterations in the immune system, which subsequently lead to the development of various psychiatric illnesses.

Longitudinal and prospective assessment of prenatal maternal sleep quality and associations with newborn hippocampal and amygdala volume

BACKGROUND

The rapid maturation of the fetal brain renders the fetus susceptible to prenatal environmental signals. Prenatal maternal sleep quality is known to have important health implications for newborns including risk for preterm birth, however, the effect on the fetal brain is poorly understood.

METHOD

Participants included 94 pregnant participants and their newborns (53% female). Pregnant participants (M_age = 30; SD_age= 5.29) reported on sleep quality three times throughout pregnancy. Newborn hippocampal and amygdala volumes were assessed using structural magnetic resonance imaging. Multilevel modeling was used to test the associations between trajectories of prenatal maternal sleep quality and newborn hippocampal and amygdala volume.

RESULTS

The overall trajectory of prenatal maternal sleep quality was associated with hippocampal volume (left: b = 0.00003, p = 0.013; right: b = 0.00003, p = .008). Follow up analyses assessing timing of exposure indicate that poor sleep quality early in pregnancy was associated with larger hippocampal volume bilaterally (e.g., late gestation left: b = 0.002, p = 0.24; right: b = 0.004, p = .11). Prenatal sleep quality was not associated with amygdala volume.

CONCLUSION

These findings highlight the implications of poor prenatal maternal sleep quality and its role in contributing to newborn hippocampal development.

Brain-immune interaction mechanisms: Implications for cognitive dysfunction in psychiatric disorders

Objectives

Cognitive dysfunction has been identified as a major symptom of a series of psychiatric disorders. Multidisciplinary studies have shown that cognitive dysfunction is monitored by a two‐way interaction between the neural and immune systems. However, the specific mechanisms of cognitive dysfunction in immune response and brain immune remain unclear.

Materials and methods

In this review, we summarized the relevant research to uncover our comprehension of the brain–immune interaction mechanisms underlying cognitive decline.

Results

The pathophysiological mechanisms of brain‐immune interactions in psychiatric‐based cognitive dysfunction involve several specific immune molecules and their associated signaling pathways, impairments in neural and synaptic plasticity, and the potential neuro‐immunological mechanism of stress.

Conclusions

Therefore, this review may provide a better theoretical basis for integrative therapeutic considerations for psychiatric disorders associated with cognitive dysfunction.

Maternal sleep deprivation induces gut microbial dysbiosis and neuroinflammation in offspring rats

Maternal sleep deprivation (MSD) is a global public health problem that affects the physical and mental development of pregnant women and their newborns. The latest research suggests that sleep deprivation (SD) disrupts the gut microbiota, leading to neuroinflammation and psychological disturbances. However, it is unclear whether MSD affects the establishment of gut microbiota and neuroinflammation in the newborns. In the present study, MSD was performed on pregnant Sprague-Dawley rats in the third trimester of pregnancy (gestational days 15-21), after which intestinal contents and brain tissues were collected from offspring at different postnatal days (P1, P7, P14, and P56). Based on microbial profiling, microbial diversity and richness increased in pregnant rats subjected to MSD, as reflected by the significant increase in the phylum Firmicutes. In addition, microbial dysbiosis marked by abundant Firmicutes bacteria was observed in the MSD offspring. Furthermore, quantitative real-time polymerase chain reaction (qRT-PCR) and enzyme-linked immunosorbent assay (ELISA) showed that the expression levels of proinflammatory cytokines interleukin 1β (IL-1β) and tumor necrosis factor α (TNF-α) were significantly higher in the MSD offspring at adulthood (P56) than in the control group. Through Spearman correlation analysis, IL-1β and TNF-α were also shown to be positively correlated with Ruminococcus_1 and Ruminococcaceae_UCG-005 at P56, which may determine the microbiota-host interactions in MSD-related neuroinflammation. Collectively, these results indicate that MSD changes maternal gut microbiota and affects the establishment of neonatal gut microbiota, leading to neuroinflammation in MSD offspring. Therefore, understanding the role of gut microbiota during physiological development may provide potential interventions for cognitive dysfunction in MSD-impacted offspring.

Rivastigmine Reverses the Decrease in Synapsin and Memory Caused by Homocysteine: Is There Relation to Inflammation?

Elevated levels of homocysteine (Hcy) in the blood, called hyperhomocysteinemia (HHcy), is a prevalent risk factor for it has been shown that Hcy induces oxidative stress and increases microglial activation and neuroinflammation, as well as causes cognitive impairment, which have been linked to the neurodegenerative process. This study aimed to evaluate the effect of mild hyperhomocysteinemia with or without ibuprofen and rivastigmine treatments on the behavior and neurochemical parameters in male rats. The chronic mild HHcy model was chemically induced in Wistar rats by subcutaneous administration of Hcy (4055 mg/kg body weight) twice daily for 30 days. Ibuprofen (40 mg/kg) and rivastigmine (0.5 mg/kg) were administered intraperitoneally once daily. Motor damage (open field, balance beam, rotarod, and vertical pole test), cognitive deficits (Y-maze), neurochemical parameters (oxidative status/antioxidant enzymatic defenses, presynaptic protein synapsin 1, inflammatory profile parameters, calcium binding adapter molecule 1 (Iba1), iNOS gene expression), and cholinergic anti-inflammatory pathway were investigated. Results showed that mild HHcy caused cognitive deficits in working memory, and impaired motor coordination reduced the amount of synapsin 1 protein, altered the neuroinflammatory picture, and caused changes in the activity of catalase and acetylcholinesterase enzymes. Both rivastigmine and ibuprofen treatments were able to mitigate this damage caused by mild HHcy. Together, these neurochemical changes may be associated with the mechanisms by which Hcy has been linked to a risk factor for AD. Treatments with rivastigmine and ibuprofen can effectively reduce the damage caused by increased Hcy levels.

Effect of rapid eye movement sleep deprivation during pregnancy on glucocorticoid receptor regulation of HPA axis function in female offspring

Poor maternal sleep quality during the different phases of pregnancy acts as a prenatal stress and is critical for fetal development. Despite the potential adverse effects of maternal stress on the behavior and physiology of the offspring, the mechanisms remain poorly understood. The present study investigates the effects of maternal sleep deprivation (SD) at different stages of pregnancy on the hypothalamic-pituitary-adrenal (HPA) axis in female offspring. The pregnant rats were subjected to sleep deprivation of 12 h per day at different stages; early (ESD), mid (MSD), and late (LSD) stages, on pregnancy days 1-7, 8-14, and 14-20, respectively. At postnatal day 60, levels of corticosterone (CORT), hypothalamic corticotropin-releasing factor receptor 1 (CRF-R1), and hippocampal glucocorticoid receptors (GR) were evaluated in the offspring. Although the hypothalamic CRF-R1 level was increased in the offspring of SD dams, immunohistochemical staining showed reduced immunoreactivity of GR in ESD and LSD offspring hippocampal area. Altogether, the data suggests that a critical period for adverse effects of SD on the HPA axis in female offspring of Wistar rats may be during early and late pregnancy.

Hydrogen Sulfide Attenuates the Cognitive Dysfunction in Parkinson's Disease Rats via Promoting Hippocampal Microglia M2 Polarization by Enhancement of Hippocampal Warburg Effect

Identification of innovative therapeutic targets for the treatment of cognitive impairment in Parkinson's disease (PD) is urgently needed. Hydrogen sulfide (H₂S) plays an important role in cognitive function. Therefore, this work is aimed at investigating whether H₂S attenuates the cognitive impairment in PD and the underlying mechanisms. In the rotenone- (ROT-) established PD rat model, NaHS (a donor of H₂S) attenuated the cognitive impairment and promoted microglia polarization from M1 towards M2 in the hippocampus of PD rats. NaHS also dramatically upregulated the Warburg effect in the hippocampus of PD rats. 2-Deoxyglucose (2-DG, an inhibitor of the Warburg effect) abolished NaHS-upregulated Warburg effect in the hippocampus of PD rats. Moreover, the inhibited hippocampal Warburg effect by 2-DG abrogated H₂S-excited the enhancement of hippocampal microglia M2 polarization and the improvement of cognitive function in ROT-exposed rats. Our data demonstrated that H₂S inhibits the cognitive dysfunction in PD via promoting microglia M2 polarization by enhancement of hippocampal Warburg effect.

Effect of multi-epitope derived from HIV-1 on REM sleep deprivation-induced spatial memory impairment with respect to the level of immune factors in mice

Objectives

Sleep deprivation (SD) has a negative impact on cognitive functions including learning and memory. Many studies have shown that rapid-eye-movement (REM) SD also disrupts memory performance. In this study, we aimed to investigate the effect of multi-epitope Gag-Pol-Env-Tat derived from Human immunodeficiency virus 1 (HIV-1) on REM SD-induced spatial memory impairment with respect to the levels of interleukin-4 (IL-4), interleukin-17 (IL-17), interferon-gamma (IFN-γ), immunoglobulin G1 (IgG1), immunoglobulin G2a (IgG2a), and lymphocyte proliferation in NMRI mice. We used multi-epitope Gag-Pol-Env-Tat derived from HIV-1 because Gag-Pol-Env-Tat immunogen sequence is one of the most sensitive immunogen sequences of HIV-1 that can significantly augment cellular and humoral immune systems, leading to the improvement of cognitive functions.

Materials and Methods

Morris water maze apparatus was used to assess spatial memory, and multi-platform apparatus was used to induce RSD for 24 hr. Multi-epitope derived from HIV-1 was subcutaneously injected at the dose of 20 µgr/ml, once and fourteen days before RSD.

Results

RSD impaired spatial memory and injection of multi-epitope derived from HIV-1 reversed this effect. RSD decreased IL-4, IgG1, and IgG2a levels, while multi-epitope derived from HIV-1 reversed these effects. Multi-epitope derived from HIV-1 also increased lymphocyte proliferation and decreased IL-17 levels in both control and RSD mice.

Conclusion

Multi-epitope derived from HIV-1 may improve memory performance via induction of anti-inflammatory immune response.

Developmental Stressors Induce Innate Immune Memory in Microglia and Contribute to Disease Risk

Many types of stressors have an impact on brain development, function, and disease susceptibility including immune stressors, psychosocial stressors, and exposure to drugs of abuse. We propose that these diverse developmental stressors may utilize a common mechanism that underlies impaired cognitive function and neurodevelopmental disorders such as schizophrenia, autism, and mood disorders that can develop in later life as a result of developmental stressors. While these stressors are directed at critical developmental windows, their impacts are long-lasting. Immune activation is a shared pathophysiology across several different developmental stressors and may thus be a targetable treatment to mitigate the later behavioral deficits. In this review, we explore different types of prenatal and perinatal stressors and their contribution to disease risk and underlying molecular mechanisms. We highlight the impact of developmental stressors on microglia biology because of their early infiltration into the brain, their critical role in brain development and function, and their long-lived status in the brain throughout life. Furthermore, we introduce innate immune memory as a potential underlying mechanism for developmental stressors' impact on disease. Finally, we highlight the molecular and epigenetic reprogramming that is known to underlie innate immune memory and explain how similar molecular mechanisms may be at work for cells to retain a long-term perturbation after exposure to developmental stressors.

Tea polyphenols protect learning and memory in sleep-deprived mice by promoting AMPA receptor internalization

Chronic sleep loss caused lots of health problems, also including cognition impairment. Tea is one of the most popular drinks when people stay up late. Nevertheless, the effects of tea on sleep deprivation-induced cognition impairment are still unclear. In the present study, we found 24-h sleep deprivation (S-DEP) increased membrane α-amino-3-hydroxy-5-methyl-4-isoxa-zolep-propionate (AMPA) receptor level through a tumor necrosis factor α (TNFα)-dependent pathway in hippocampi. Blocking elevated TNFα level can protect S-DEP mice from impaired learning ability according to behavioral test. Tea polyphenols, major active compounds in green tea, suppressed TNFα production through downregulating TNFα converting enzyme (TACE) level. Meanwhile, tea polyphenols treatment could ameliorate recognition impairment and anxiety-like behaviors in S-DEP mice. The aforementioned results demonstrate cognition protective effects of tea polyphenols in S-DEP mice model, which provide a theoretical basis for the treatments of S-DEP-induced cognition impairment by targeting the TACE/TNFα/AMPA pathway.

Highlighting Immune System and Stress in Major Depressive Disorder, Parkinson's, and Alzheimer's Diseases, with a Connection with Serotonin

There is recognition that both stress and immune responses are important factors in a variety of neurological disorders. Moreover, there is an important role of several neurotransmitters that connect these factors to several neurological diseases, with a special focus in this paper on serotonin. Accordingly, it is known that imbalances in stressors can promote a variety of neuropsychiatric or neurodegenerative pathologies. Here, we discuss some facts that link major depressive disorder, Alzheimer’s, and Parkinson’s to the stress and immune responses, as well as the connection between these responses and serotonergic signaling. These are important topics of investigation which may lead to new or better treatments, improving the life quality of patients that suffer from these conditions.

An emerging role for microglia in stress‐effects on memory

Stressful experiences evoke, among others, a rapid increase in brain (nor)epinephrine (NE) levels and a slower increase in glucocorticoid hormones (GCs) in the brain. Microglia are key regulators of neuronal function and contain receptors for NE and GCs. These brain cells may therefore potentially be involved in modulating stress effects on neuronal function and learning and memory. In this review, we discuss that stress induces (1) an increase in microglial numbers as well as (2) a shift toward a pro‐inflammatory profile. These microglia have (3) impaired crosstalk with neurons and (4) disrupted glutamate signaling. Moreover, microglial immune responses after stress (5) alter the kynurenine pathway through metabolites that impair glutamatergic transmission. All these effects could be involved in the impairments in memory and in synaptic plasticity caused by (prolonged) stress, implicating microglia as a potential novel target in stress‐related memory impairments.

Naringenin Ameliorates Chronic Sleep Deprivation-Induced Pain via Sirtuin1 Inhibition

Growing experimental evidences have suggested the reciprocal correlation between sleep deprivation and pain. Inflammation and oxidative stress are among the key pathways underlying this correlation. Therefore, the present study was aimed to assess the effect of antioxidant and anti-inflammatory compound naringenin (NGN) against chronic sleep deprivation (CSD)-induced mechanical and thermal hyperalgesia in female Swiss albino mice. In this study, mice were chronically sleep-deprived for 8 h a day for five days a week with the weekend as a free sleep period and continued for nine weeks using a modified multiple platform method. The pain behavioral tests were conducted at the end of the fourth week to assess the development of hyperalgesia followed by the administration of NGN and a combination of NGN with Sirtinol (SIR, a sirtuin1 inhibitor) till the end of the study. After nine weeks, pain behavioral tests, along with oxidative stress and inflammatory parameters in cortex and striatum, were assessed. Results indicated that CSD-induced hyperalgesia in mice accompanied by increased oxidative stress and inflammatory markers in cortex and striatum of the brain. NGN combatted the hyperalgesic response and also decreased levels of oxidative stress and inflammatory markers. Furthermore, the pharmacological effect of NGN was mitigated with SIR. Thus, the findings of the present study reveal that NGN is acting via sirtuin1 to exert its antinociceptive activity against CSD-induced hyperalgesia.

Microglia Fighting for Neurological and Mental Health: On the Central Nervous System Frontline of COVID-19 Pandemic

Coronavirus disease 2019 (COVID-19) is marked by cardio-respiratory alterations, with increasing reports also indicating neurological and psychiatric symptoms in infected individuals. During COVID-19 pathology, the central nervous system (CNS) is possibly affected by direct severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) invasion, exaggerated systemic inflammatory responses, or hypoxia. Psychosocial stress imposed by the pandemic further affects the CNS of COVID-19 patients, but also the non-infected population, potentially contributing to the emergence or exacerbation of various neurological or mental health disorders. Microglia are central players of the CNS homeostasis maintenance and inflammatory response that exert their crucial functions in coordination with other CNS cells. During homeostatic challenges to the brain parenchyma, microglia modify their density, morphology, and molecular signature, resulting in the adjustment of their functions. In this review, we discuss how microglia may be involved in the neuroprotective and neurotoxic responses against CNS insults deriving from COVID-19. We examine how these responses may explain, at least partially, the neurological and psychiatric manifestations reported in COVID-19 patients and the general population. Furthermore, we consider how microglia might contribute to increased CNS vulnerability in certain groups, such as aged individuals and people with pre-existing conditions.

Chronic Treatment With Hydrogen Sulfide Donor GYY4137 Mitigates Microglial and Astrocyte Activation in the Spinal Cord of Streptozotocin-Induced Diabetic Rats

Long-term diabetic patients suffer immensely from diabetic neuropathy. This study was designed to investigate the effects of hydrogen sulfide (H2S) on peripheral neuropathy, activation of microglia, astrocytes, and the cascade secretion of proinflammatory cytokines in the streptozotocin (STZ)-induced peripheral diabetic neuropathy rat model. STZ-induced diabetic rats were treated with the water-soluble, slow-releasing H2S donor GYY4137 (50 mg/kg; i.p.) daily for 4 weeks. Antiallodynic/antihyperalgesic activities were evaluated using different tests and histopathological changes and the expression of proinflammatory cytokines in the spinal cord were examined. GYY4137 treatment produced neuroprotective effects in the spinal cord of diabetic animals and modulated their sensory deficits. The treatment decreased allodynia (p < 0.05) and mechanical hyperalgesia (p < 0.01) and restored thermal hyperalgesia (p < 0.001) compared with diabetic rats. The treatment decreased the microglial response and increased astrocyte counts in spinal cord gray and white matter compared with untreated diabetic rats. Proinflammatory cytokines were reduced in the treated group compared with diabetic rats. These results suggest that H2S has a potentially ameliorative effect on the neuropathic pain through the control of astrocyte activation and microglia-mediated inflammation, which may be considered as a possible treatment of peripheral nerve hypersensitivity in diabetic patients.

Modulating microglia activation prevents maternal immune activation induced schizophrenia-relevant behavior phenotypes via arginase 1 in the dentate gyrus

Prenatal infection during pregnancy increases the risk for developing neuropsychiatric disorders such as schizophrenia. This is linked to an inflammatory microglial phenotype in the offspring induced by maternal immune activation (MIA). Microglia are crucial for brain development and maintenance of neuronal niches, however, whether and how their activation is involved in the regulation of neurodevelopment remains unclear. Here, we used a MIA rodent model in which polyinosinic: polycytidylic acid (poly (I:C)) was injected into pregnant mice. We found fewer parvalbumin positive (PV+) cells and impaired GABAergic transmission in the dentate gyrus (DG), accompanied by schizophrenia-like behavior in the adult offspring. Minocycline, a potent inhibitor of microglia activation, successfully prevented the above-mentioned deficits in the offspring. Furthermore, by using microglia-specific arginase 1 (Arg1) ablation as well as overexpression in DG, we identified a critical role of Arg1 in microglia activation to protect against poly (I:C) imparted neuropathology and altered behavior in offspring. Taken together, our results highlight that Arg1-mediated alternative activation of microglia are potential therapeutic targets for psychiatric disorders induced by MIA.

Effects of sleep modulation during pregnancy in the mother and offspring: Evidences from preclinical research

Disturbed sleep during gestation may lead to adverse outcomes for both mother and child. Animal research plays an important role in providing insights into this research field by enabling ethical and methodological requirements that are not possible in humans. Here, we present an overview and discuss the main research findings related to the effects of prenatal sleep deprivation in animal models. Using systematic review approaches, we retrieved 42 articles dealing with some type of sleep alteration. The most frequent research topics in this context were maternal sleep deprivation, maternal behaviour, offspring behaviour, development of sleep-wake cycles in the offspring, hippocampal neurodevelopment, pregnancy viability, renal physiology, hypertension and metabolism. This overview indicates that the number of basic studies in this field is growing, and provides biological plausibility to suggest that sleep disturbances might be detrimental to both mother and offspring by promoting increased risk at the behavioural, hormonal, electrophysiological, metabolic and epigenetic levels. More studies on the effects of maternal sleep deprivation are needed, in light of their major translational perspective.

Pioglitazone alleviates maternal sleep deprivation-induced cognitive deficits in male rat offspring by enhancing microglia-mediated neurogenesis

Maternal sleep disturbance in pregnancy causes cognitive impairments and emotional disorders in offspring. Microglia-mediated inflammatory processes contribute to prenatal stress-induced neurodevelopmental deficits. Peroxisome proliferator-activated receptor gamma (PPARγ) activation underlies the switching of microglial activation phenotypes, which has emerged as a pharmacological target for regulating neuroinflammatory responses in the treatment of neuropsychiatric disorders. Here we investigated the effects of PPARγ-dependent microglial activation on neurogenesis and cognitive behavioral outcomes in male rat offspring exposed to maternal sleep deprivation (MSD) for 72 h from days 18-21 of pregnancy. In the Morris water maze test, male MSD rat offspring needed more time than control offspring to escape to the hidden platform and spent less time in the target quadrant when the hidden platform was removed. In MSD rat offspring, microglial density as determined by immunofluorescence was higher, microglia showed fewer and shorter processes, and neurogenesis in the hippocampus was significantly reduced. Levels of mRNA encoding pro-inflammatory markers IL-6, TNFα, and IL-1β were higher in male MSD offspring, whereas levels of anti-inflammatory markers Arg1, IL-4, and IL-10 were lower, as was PPARγ expression in the hippocampus. PPARγ activation by pioglitazone (30 mg/kg/day, i.p., 7 d) mitigated these negative effects of MSD, rescuing hippocampal neurogenesis and improving cognitive function. The PPARγ inhibitor GW9662 (1 mg/kg/day, i.p., 7 d) eliminated the effects of pioglitazone. Conditioned medium from pioglitazone-treated microglia promoted proliferation and differentiation of neural progenitor cells. These results suggest that MSD-induced deficits in spatial learning and memory can be ameliorated through PPARγ-dependent modulation of microglial phenotypes.

Prenatal Exposure to Valproic Acid Affects Microglia and Synaptic Ultrastructure in a Brain-Region-Specific Manner in Young-Adult Male Rats: Relevance to Autism Spectrum Disorders

Autism spectrum disorders (ASD) are a heterogeneous group of neurodevelopmental conditions categorized as synaptopathies. Environmental risk factors contribute to ASD aetiology. In particular, prenatal exposure to the anti-epileptic drug valproic acid (VPA) may increase the risk of autism. In the present study, we investigated the effect of prenatal exposure to VPA on the synaptic morphology and expression of key synaptic proteins in the hippocampus and cerebral cortex of young-adult male offspring. To characterize the VPA-induced autism model, behavioural outcomes, microglia-related neuroinflammation, and oxidative stress were analysed. Our data showed that prenatal exposure to VPA impaired communication in neonatal rats, reduced their exploratory activity, and led to anxiety-like and repetitive behaviours in the young-adult animals. VPA-induced pathological alterations in the ultrastructures of synapses accompanied by deregulation of key pre- and postsynaptic structural and functional proteins. Moreover, VPA exposure altered the redox status and expression of proinflammatory genes in a brain region-specific manner. The disruption of synaptic structure and plasticity may be the primary insult responsible for autism-related behaviour in the offspring. The vulnerability of specific synaptic proteins to the epigenetic effects of VPA may highlight the potential mechanisms by which prenatal VPA exposure generates behavioural changes.

Adipose-derived mesenchymal stem cells protect against CMS-induced depression-like behaviors in mice via regulating the Nrf2/HO-1 and TLR4/NF-κB signaling pathways

Increasing studies show that inflammatory processes may be involved in depressive disorders. Nuclear factor erythroid-2 related factor 2 (Nrf2) modulates tissue microglial M1 phenotypic changes to the M2 phenotype, which is implicated in protection against inflammatory diseases. We have reported that the adipose-derived mesenchymal stem cells (ADSCs) display anti-inflammatory activity. In this study we explored whether the mechanism of anti-inflammatory activity of ADSCs was related to Nrf2. ADSCs were isolated from mouse fat pads and intravenously administered to chronic mild stress (CMS)-exposed C57BL/6 mice at the dose of 1 × 10⁶ once a week for 3 weeks. We showed that ADSC administration significantly remedied CMS-induced depressive-like behaviors in sucrose preference test, tail suspension test, and forced swim test accompanied by suppressing microglial activation and the expression of inflammatory factors including MCP-1, TNF-α, IL-1β, and IL-6. Furthermore, ADSC administration promoted both the expression of BDNF and TrkB, and promoted Nrf2/HO-1 signaling but suppressed TLR4/NF-κB signaling in brain tissue. In order to elucidate the role of Nrf2/HO-1 signaling in ADSC-caused neuroprotection, Nrf2-modified ADSCs were cocultured with BV2 microglial cells, then exposed to lipopolysaccharide (LPS). Downregulation of Nrf2 in ADSCs decreased the protective effects of ADSCs against LPS-induced microglial activation and M1 polarization. Nrf2 overexpression in ADSCs markedly suppressed LPS-induced TLR4 and NF-κB expression in microglial cells. These results suggest a possible antidepressive mechanism correlated with microglial polarization for anti-inflammatory agents, which may provide a new microglia-targeted strategy for depression therapy.

Exposure to nonylphenol in early life increases pro-inflammatory cytokines in the prefrontal cortex: Involvement of gut-brain communication

A growing body of evidence indicates that exposure to nonylphenol (NP), a typical persistent organic pollutant (POP), in early life results in the impairment of the central nervous system (CNS), but the underlying mechanism still remains to be elucidated. High levels of pro-inflammatory cytokines in the brain have been implicated in the CNS damages. The animal model of exposure to NP in early life was established by maternal gavage during the pregnancy and lactation in the present study. We found that exposure to NP in early life increased the levels of pro-inflammatory cytokines in the rat prefrontal cortex. Interestingly, the levels of pro-inflammatory cytokines in the intestine as well as in the serum were also increased by NP exposure. Furthermore, the increased permeability of intestinal barrier and blood-brain barrier (BBB), two critical barriers in the gut to brain communication, was observed in the rats exposed to NP in early lives. The decreased expression of zonula occludens-1 (ZO-1) and claudin-1 (CLDN-1), tight junction proteins (TJs) that responsible for maintaining the permeability of intestinal barrier and BBB, was found, which may underlie these increases in permeability. Taken together, these results suggested that the disturbed gut-brain communication may contribute to the increased levels of pro-inflammatory cytokines in the prefrontal cortex caused by NP exposure in early life.

Imipramine and Venlafaxine Differentially Affect Primary Glial Cultures of Prenatally Stressed Rats

Here, we examine the effects of prenatal administration of two antidepressants—imipramine (IMI) and venlafaxine (VEN)—on morphology and activity of a primary glial culture. Microglia are targeted by antidepressants used for antenatal depression and are important regulators of central nervous system development. In this study, female Wistar rats were assigned to one of four groups: a control group that received water ad libitum (1), and groups that received additionally once daily either water (2), IMI (10 mg/kg) (3), or VEN (20 mg/kg) (4) by oral gavage from gestation day 7 to 22. Oral gavage administration induced prenatal stress. Cell cultures were obtained from the brains of 1-day-old pups. Prenatal stress caused a disturbance of sensorimotor function in pups. Prenatal stress also produced alterations in the glial cultures, specifically, an increased percentage of microglia in the mixed glial cultures and an increased percentage of dead cells. Moreover, increased levels of IL1-β, TNF-α, NO, and an increased expression of CX3CR1 mRNA were found in microglia. However, the ratio of Bax/Bcl2 mRNA was reduced. Prenatal stress increased the vulnerability of microglia to lipopolysaccharide (LPS). The mixed glial culture derived from pups exposed to IMI showed greater morphological changes and the highest percentage of microglia. Microglia were characterized by the largest increase in the production of pro-inflammatory cytokines and NO, and the greatest reduction in the expression of CX3CR1 mRNA. Exposure to IMI reduced the effects of LPS on IL-1β production and Bax/Bcl2 mRNA, and exacerbated the effects of LPS on CX3CR1 mRNA expression. Prenatal administration of VEN induced protective effects on microglia, as measured by all studied parameters. Taken together, our data suggest that, by disturbing microglia function, exposure to even mild forms of chronic prenatal stress may predispose individuals to psychiatric or neurodevelopmental disorders. These data also indicate that chronic mild stress sensitizes microglia to immune challenges, which may lead to enhanced neuronal damage in the embryonic brain. The observed detrimental effects of IMI on microglial activity under conditions of prenatal stress may help to explain the teratogenic effects of IMI reported in the literature.

Short-term sleep deprivation in mice induces B cell migration to the brain compartment

Increasing evidence highlight the involvement of immune cells in brain activity and its dysfunction. The brain's immune compartment is a dynamic ensemble of cells that can fluctuate even in naive animals. However, the dynamics and factors that can affect the composition of immune cells in the naive brain are largely unknown. Here, we examined whether acute sleep deprivation can affect the brain's immune compartment (parenchyma, meninges, and choroid plexus). Using high-dimensional mass cytometry analysis, we broadly characterized the effects of short-term sleep deprivation on the immune composition in the mouse brain. We found that after 6 h of sleep deprivation, there was a significant increase in the abundance of B cells in the brain compartment. This effect can be accounted for, at least in part, by the elevated expression of the migration-related receptor, CXCR5, on B cells and its ligand, cxcl13, in the meninges following sleep deprivation. Thus, our study reveals that short-term sleep deprivation affects the brain's immune compartment, offering a new insight into how sleep disorders can affect brain function and potentially contribute to neurodegeneration and neuroinflammation.

Microglial Function in the Effects of Early-Life Stress on Brain and Behavioral Development

The putative effects of early-life stress (ELS) on later behavior and neurobiology have been widely investigated. Recently, microglia have been implicated in mediating some of the effects of ELS on behavior. In this review, findings from preclinical and clinical literature with a specific focus on microglial alterations induced by the exposure to ELS (i.e., exposure to behavioral stressors or environmental agents and infection) are summarized. These studies were utilized to interpret changes in developmental trajectories based on the time at which the stress occurred, as well as the paradigm used. ELS and microglial alterations were found to be associated with a wide array of deficits including cognitive performance, memory, reward processing, and processing of social stimuli. Four general conclusions emerged: (1) ELS interferes with microglial developmental programs, including their proliferation and death and their phagocytic activity; (2) this can affect neuronal and non-neuronal developmental processes, which are dynamic during development and for which microglial activity is instrumental; (3) the effects are extremely dependent on the time point at which the investigation is carried out; and (4) both pre- and postnatal ELS can prime microglial reactivity, indicating a long-lasting alteration, which has been implicated in behavioral abnormalities later in life.

Effect of Acupuncture on Pregnancy-Related Insomnia and Melatonin: A Single-Blinded, Randomized, Placebo-Controlled Trial

OBJECTIVE

The aim of the current study is to evaluate the efficacy and safety of acupuncture on sleep quality and overnight melatonin secretion, measured as urinary 6-sulfatoxymelatonin, in pregnant women.

PATIENTS AND METHODS

This randomized, parallel, single-blinded (participant), controlled trial was conducted on 72 pregnant women with insomnia. Study participants were randomly assigned to either the intervention, 10 sessions of acupuncture treatment over a 3-week period, or control group by block randomization (1:1). Patients in both groups were evaluated at baseline and post-treatment (third week) using the Pittsburgh Sleep Quality Index (PSQI) score (as the primary outcome) and urinary 6-sulfatoxymelatonin.

RESULTS

Fifty-five of 72 participants completed the study. There was no statistically significant difference regarding PSQI score and 6-sulfatoxymelatonin level between intervention and control groups at the baseline (P=0.169 and P=0.496). At the end of the study period, treatment with acupuncture significantly improved the PSQI score (P<0.001) with a large effect size of 3.7, as well as 6-sulfatoxymelatonin level (P=0.020) with a medium effect size of 0.6 as compared to the control group. No adverse effects were noted during acupuncture sessions and follow-up visits.

CONCLUSION

Acupuncture was shown to significantly improve the sleep quality in pregnant women, possibly through increasing melatonin secretion, and could be recommended as a low-cost and low-risk alternative treatment to pharmacological therapies.

Acute sleep deprivation during pregnancy in rats: Rapid elevation of placental and fetal inflammation and kynurenic acid

The kynurenine pathway (KP) is the dominant pathway for tryptophan degradation in the mammalian body and emerging evidence suggests that acute episodes of sleep deprivation (SD) disrupt tryptophan metabolism via the KP. Increases in the neuroactive KP metabolite kynurenic acid (KYNA) during pregnancy may lead to a higher risk for disrupted neurodevelopment in the offspring. As pregnancy is a critical period during which several factors, including sleep disruptions, could disrupt the fetal environment, we presently explored the relationship between maternal SD and KP metabolism and immune pathways in maternal, placenta, and fetal tissues. Pregnant Wistar rat dams were sleep deprived by gentle handling for 5 h from zeitgeber time (ZT) 0 to ZT 5. Experimental cohorts included: i) controls, ii) one session of SD on embryonic day (ED) 18 or iii) three sessions of SD occurring daily on ED 16, ED 17 and ED 18. Maternal (plasma, brain), placental and fetal (plasma, brain) tissues were collected immediately after the last session of SD or after 24 h of recovery from SD. Respective controls were euthanized at ZT 5 on ED 18 or ED 19. Maternal plasma corticosterone and fetal brain KYNA were significantly elevated only after one session of SD on ED 18. Importantly, maternal plasma corticosterone levels correlated significantly with fetal brain KYNA levels. In addition, placental levels of the proinflammatory cytokines interleukin-1β (IL-1β) and interleukin-6 (IL-6) were increased following maternal SD, suggesting a relationship between placental immune response to SD and fetal brain KYNA accumulation. Collectively, our results demonstrate that sleep loss during the last week of gestation can adversely impact maternal stress, placental immune function, and fetal brain KYNA levels. We introduce KYNA as a novel molecular target influenced by sleep loss during pregnancy.

•

Prenatal sleep deprivation influences kynurenine pathway metabolism in utero.

•

Fetal brain kynurenic acid (KYNA) is elevated after maternal sleep deprivation.

•

Maternal plasma corticosterone is increased after sleep deprivation.

•

Prenatal sleep deprivation induces placental and fetal brain cytokines.

•

These data support an interplay with stress, in utero inflammation, and KYNA.

Characterization and modulation of microglial phenotypes in an animal model of severe sepsis

We aim to characterize the kinetics of early and late microglial phenotypes after systemic inflammation in an animal model of severe sepsis and the effects of minocycline on these phenotypes. Rats were subjected to CLP, and some animals were treated with minocycline (10 ug/kg) by i.c.v. administration. Animals were killed 24 hours, 5, 10 and 30 days after sepsis induction, and serum and hippocampus were collected for subsequent analyses. Real‐time PCR was performed for M1 and M2 markers. TNF‐α, IL‐1β, IL‐6, IL‐10, CCL‐22 and nitrite/nitrate levels were measured. Immunofluorescence for IBA‐1, CD11b and arginase was also performed. We demonstrated that early after sepsis, there was a preponderant up‐regulation of M1 markers, and this was not switched to M2 phenotype markers later on. We found that up‐regulation of both M1 and M2 markers co‐existed up to 30 days after sepsis induction. In addition, minocycline induced a down‐regulation, predominantly, of M1 markers. Our results suggest early activation of M1 microglia that is followed by an overlap of both M1 and M2 phenotypes and that the beneficial effects of minocycline on sepsis‐associated brain dysfunction may be related to its effects predominantly on the M1 phenotype.

Impaired plasmalogen synthesis dysregulates liver X receptor-dependent transcription in cerebellum

Synthesis of ethanolamine plasmalogen (PlsEtn) is regulated by modulating the stability of fatty acyl-CoA reductase 1 (Far1) on peroxisomal membrane, a rate-limiting enzyme in plasmalogen synthesis. Dysregulation of plasmalogen homeostasis impairs cholesterol biosynthesis in cultured cells by altering the stability of squalene epoxidase (SQLE). However, regulation of PlsEtn synthesis and physiological consequences of plasmalogen homeostasis in tissues remain unknown. In the present study, we found that the protein but not the transcription level of Far1 in the cerebellum of the Pex14 mutant mouse expressing Pex14p lacking its C-terminal region (Pex14ΔC/ΔC) is higher than that from wild-type mouse, suggesting that Far1 is stabilized by the lowered level of PlsEtn. The protein level of SQLE was increased, whereas the transcriptional activity of the liver X receptors (LXRs), ligand-activated transcription factors of the nuclear receptor superfamily, is lowered in the cerebellum of Pex14ΔC/ΔC and the mice deficient in dihydroxyacetonephosphate acyltransferase, the initial enzyme for the synthesis of PlsEtn. These results suggest that the reduction of plasmalogens in the cerebellum more likely compromises the cholesterol homeostasis, thereby reducing the transcriptional activities of LXRs, master regulators of cholesterol homeostasis.

Minocycline inhibits microglial activation and alleviates depressive-like behaviors in male adolescent mice subjected to maternal separation

Exposure to early adversity increases vulnerability to psychiatric disorders in later life. Microglia-mediated inflammation has been linked to psychopathology, so such inflammation may be a target for treating depression. Using a model of depression involving adolescent male C57BL/6J mice subjected to maternal separation, we explored whether using minocycline to mitigate inflammation can alleviate depression-like behaviors. Between postnatal days 1 and 14, male mice were separated from their mothers for 3 h per day. Minocycline (20 mg/kg) was administered intraperitoneally once daily for 2 weeks starting one week after weaning. Then the male mice were subjected to a second stress for 2 weeks. Results from the sucrose preference test, forced swimming test, and open field test showed that maternal separation did not obviously alter behavior of the male mice, but it did increase the risk of depression-like behaviors following a second stress. This increased risk disappeared if minocycline was given preemptively before the second stress. Maternal separation and second stress up-regulated pro-inflammatory markers and down-regulated anti-inflammatory markers in the hippocampus, and they activated microglia and promoted pro-inflammatory transitions in microglia. All these effects were reversed by minocycline. These changes in inflammatory processes correlated with changes in neurogenesis and BDNF expression in the hippocampus. Our results in this mouse model suggest the potential of minocycline for treating psychiatric disorders induced by early adversity.

Icariin Attenuates M1 Activation of Microglia and Aβ Plaque Accumulation in the Hippocampus and Prefrontal Cortex by Up-Regulating PPARγ in Restraint/Isolation-Stressed APP/PS1 Mice

Background

Studies have shown that psychosocial stress is involved in Alzheimer's disease (AD) pathogenesis; it induces M1 microglia polarization and production of pro-inflammatory cytokines, leading to neurotoxic outcomes and decreased β-amyloid (Aβ) clearance. Icariin has been proven to be an effective anti-inflammatory agent and to activate peroxisome proliferator-activated receptors gamma (PPARγ) which induces the M2 phenotype in the microglia. However, whether restraint/isolation stress reduces the clearance ability of microglia by priming and polarizing microglia to the M1 phenotype, and the effects of icariin in attenuating the inflammatory response and relieving the pathological changes of AD are still unclear.

Methods

APP/PS1 mice (male, aged 3 months) were randomly divided into a control group, a restraint/isolation stress group, and a restraint/isolation stress + icariin group. The restraint/isolation stress group was subjected to a paradigm to build a depressive animal model. Sucrose preference, open field, elevated plus maze, and Y maze test were used to assess the stress paradigm. The Morris water maze test was performed to evaluate spatial reference learning and memory. Enzyme-linked immunosorbent assay and immunohistochemistry were used to identify the microglia phenotype and Aβ accumulation. Western blotting was used to detect the expression of PPARγ in the hippocampus and prefrontal cortex (PFC).

Results

Restraint/isolation stress induced significant depressive-like behaviors in APP/PS1 mice at 4 months of age and memory impairment at 10 months of age, while 6 months of icariin administration relieved the memory damage. Restraint/isolation stressed mice had elevated pro-inflammatory cytokines, decreased anti-inflammatory cytokines, increased Aβ plaque accumulation and more M1 phenotype microglia in the hippocampus and PFC at 10 months of age, while 6 months of icariin administration relieved these changes. Moreover, restraint/isolation stressed mice had down-regulated PPARγ expression in the hippocampus and PFC at 10 months of age, while 6 months of icariin administration reversed the alteration, especially in the hippocampus.

Conclusion

Restraint/isolation stress induced depressive-like behaviors and spatial memory damage, over-expression of M1 microglia markers and more severe Aβ accumulation by suppressing PPARγ in APP/PS1 mice. Icariin can be considered a new treatment option as it induces the switch of the microglia phenotype by activating PPARγ.

Prenatal Developmental Origins of Future Psychopathology: Mechanisms and Pathways

The developmental origins of health and disease hypothesis applied to neurodevelopmental outcomes asserts that the fetal origins of future development are relevant to mental health. There is a third pathway for the familial inheritance of risk for psychiatric illness beyond shared genes and the quality of parental care: the impact of pregnant women's distress-defined broadly to include perceived stress, life events, depression, and anxiety-on fetal and infant brain-behavior development. We discuss epidemiological and observational clinical data demonstrating that maternal distress is associated with children's increased risk for psychopathology: For example, high maternal anxiety is associated with a twofold increase in the risk of probable mental disorder in children. We review several biological systems hypothesized to be mechanisms by which maternal distress affects fetal and child brain and behavior development, as well as the clinical implications of studies of the developmental origins of health and disease that focus on maternal distress. Development and parenting begin before birth.

Maternal stress and early-onset colorectal cancer

Early-onset colorectal cancer (EOCRC) is defined as colorectal cancer (CRC) diagnosed before the age of 50. Alarmingly, there has been a significant increase in EOCRC diagnoses' worldwide over the past several decades. Emerging data suggest EOCRCs have distinguishing clinical, pathological, biological and molecular features; and thus, are a fundamentally different subtype of CRCs. Unfortunately, there is no simple explanation for the causes of EOCRC. Scientifically rigorous studies are needed to determine what may be driving the challenging epidemiology of EOCRC. We contend here that a reasonable hypothesis is that prenatal risk factors such as maternal stress and associated sleeping disorders influence offspring epigenetic make-up, and shape immune system and gut health contributing to an increased risk for EOCRC.

Early Maternal Deprivation Induces Microglial Activation, Alters Glial Fibrillary Acidic Protein Immunoreactivity and Indoleamine 2,3-Dioxygenase during the Development of Offspring Rats

Maternal deprivation (MD) induces behavioral changes and impacts brain circuits that could be associated with the pathophysiology of depression. This study investigated the markers of microglia and astrocyte activation as well as indoleamine 2,3-dioxygenase (IDO) expression in developmental programming after early life MD (on postnatal days (PNDs) 20, 30, 40, and 60). On PND 60, the rats that were subjected to MD displayed depressive-like behavior. On PND 10, it was found that there was a decrease in the level of glial fibrillary acidic protein (GFAP) immunopositive cells, a decrease in the level of IDO expression, and an increase in the level of Iba-1 (microglial marker) in the hippocampus of rats that were subjected to MD. On PND 20, levels of GFAP were also found to have decreased in the hippocampus, and there was an increase in the level of Iba-1 in the hippocampus. AIF-1 (microglial marker) expression was observed in the PFC following MD. On PND 30, the levels of Iba-1 remained elevated. On PND 40, the levels of GFAP were found to have increased in the hippocampus of rats that were subjected to MD. On PND 60, the levels of GFAP and AIF-1 remained elevated following MD. These results suggest that early life stress induces negative developmental programming in rats, as demonstrated by depressive-like behavior in adult life. Moreover, MD increases microglial activation in both early and late developmental phases. The levels of GFAP and IDO decreased in the early stages but were found to be higher in later developmental periods. These findings suggest that MD could differentially affect the expression of the IDO enzyme, astrocytes, and microglial activation depending on the neurodevelopmental period. The onset of an inflammatory state from resident brain cells could be associated with the activation of the kynurenine pathway and the development of depressive behavior in adulthood.

Sex differences in effects of gestational polychlorinated biphenyl exposure on hypothalamic neuroimmune and neuromodulator systems in neonatal rats

Polychlorinated biphenyls (PCBs) are ubiquitous in the environment and exposure to them is associated with immune, endocrine and neural dysfunction. Effects of PCBs on inflammation and immunity are best described in spleen and blood, with fewer studies on neural tissues. This is an important gap in knowledge, as molecules typically associated with neuroinflammation also serve neuromodulatory roles and interact with hormones in normal brain development. The current study used Sprague-Dawley rats to assess whether gestational PCB exposure altered hypothalamic gene expression and serum cytokine concentration in neonatal animals given an immune challenge. Dams were fed wafers containing a mixture of PCBs at an environmentally relevant dose and composition (20 μg/kg, 1:1:1 Aroclor 1242:1248:1254) or oil vehicle control throughout their pregnancy. One day old male and female offspring were treated with an inflammatory challenge (lipopolysaccharide, LPS, 50 μg/kg, sc) or saline vehicle control approximately 3.5 h prior to tissue collection. Across both basal and activated inflammatory states, PCB exposure caused greater expression of a subset of inflammatory genes in the hypothalamus and lower expression of genes involved in dopamine, serotonin, and opioid systems compared to oil controls. PCB exposure also altered reactions to inflammatory challenge: it reversed the normal decrease in Esr2 hypothalamic expression and induced an abnormal increase in IL-1b and IL-6 serum concentration in response to LPS. Many of these effects were sex specific. Given the potential long-term consequences of neuroimmune disruption, our findings demonstrate the need for further research.

Facilitated AMPAR endocytosis causally contributes to the maternal sleep deprivation-induced impairments of synaptic plasticity and cognition in the offspring rats

Maternal sleep deprivation (MSD) has been suggested to be associated with increased frequency of neurodevelopmental disorders in offspring in both humans and animal models. However, the underlying cellular and molecular mechanism is still unclear. We have recently reported that MSD at different stages of pregnancy impairs the emotional and cognitive functions, and suppresses hippocampal CA1 long-term potentiation (LTP) in the offspring rats. Here, we report that the MSD induced LTP impairment at the CA1 hippocampus of the offspring rats is associated with increased long-term depression (LTD) and reduced expression of postsynaptic GluA2-containing α-amino-3-hydroxy-5-methyl-isoxazole-4-propionic acid receptors (AMPARs). Importantly, we found that inhibition of AMPAR endocytosis by a synthetic peptide Tat-GluA2_3Y (3 μmol/kg, i.p.) not only increased level of AMPARs and reduced LTD, but also restored LTP. Moreover, treatment with Tat-GluA2_3Y peptide markedly alleviated the MSD-induced impairments of spatial learning and memory; and decreased depressive- and anxiety-like behaviors in the offspring. Together, our findings suggest that the MSD-induced postsynaptic AMPAR endocytosis causally contributes to the impairments of hippocampal synaptic plasticity, thereby disrupting the emotional and cognitive functions in the offspring.