Long-Term Environmental Enrichment Relieves Dysfunctional Cognition and Synaptic Protein Levels Induced by Prenatal Inflammation in Older CD-1 Mice

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.

An enriched environment ameliorates maternal sleep deprivation-induced cognitive impairment in aged mice by improving mitochondrial function via the Sirt1/PGC-1α pathway

BACKGROUND

Early life stress can cause cognitive impairment in aged offspring. Environmental enrichment (EE) is considered to be an effective non-pharmacological treatment for improving cognitive decline. The aim of this research was to evaluate the effect of EE, on cognitive impairment in aged offspring induced by maternal sleep deprivation (MSD) and the underlying mechanisms involved to investigate its potential value in clinical practice.

METHODS

CD-1 damns were subjected or not to sleep deprivation during late gestation. Twenty-one days after birth, the offspring were assigned to standard or EE cages. At 18 months-old, the learning and memory function of the offspring mice was evaluated using Morris water maze. The hippocampal and prefrontal cortical levels of protein, gene, proinflammation cytokines, and oxidative stress indicators was examined by Western blot, real-time polymerase chain reaction, enzyme linked immunosorbent assay, and biochemical assays.

RESULTS

Offspring in MSD group exhibited declined learning and memory abilities compared with control animals. Moreover, the hippocampal and prefrontal cortical levels of Sirtuin1 (Sirt1), peroxisome proliferator-activated receptor-gamma coactivator-1 alpha (PGC-1α), postsynaptic density protein-95, and synaptophysin were lower and those of proinflammation cytokines higher in the MSD group; meanwhile, the superoxide dismutase content was higher and the malondialdehyde and reactive oxygen species contents were lower. However, these deleterious changes were ameliorated by exposure to EE.

CONCLUSIONS

EE attenuates MSD-induced cognitive impairment, oxidative stress, and neuroinflammation and reverses the reduction in synaptic protein levels in aged offspring mice via the Sirt1/PGC-1α pathway.

Land/Water Aerobic Activities: Two Sides of the Same Coin. A Comparative Analysis on the Effects in Cognition of Alzheimer's Disease

 Evidence in the literature indicates that aerobic physical activity may have a protective role in aging pathologies. However, it has not been clarified whether different types of aerobic exercise produce different effects. In particular, these potential differences have not been explored in patients with Alzheimer's disease (AD). The present narrative review has the specific aim of evaluating whether land (walking/running) and water (swimming) aerobic activities exert different effects on cognitive functions and neural correlates in AD patients. In particular, the investigation is carried out by comparing the evidence provided from studies on AD animal models and on patients. On the whole, we ascertained that both human and animal studies documented beneficial effects of land and water aerobic exercise on cognition in AD. Also, the modulation of numerous biological processes is documented in association with structural modifications. Remarkably, we found that aerobic activity appears to improve cognition per se, independently from the specific kind of exercise performed. Aerobic exercise promotes brain functioning through the secretion of molecular factors from skeletal muscles and liver. These molecular factors stimulate neuroplasticity, reduce neuroinflammation, and inhibit neurodegenerative processes leading to amyloid-β accumulation. Additionally, aerobic exercise improves mitochondrial activity, reducing oxidative stress and enhancing ATP production. Aerobic activities protect against AD, but implementing exercise protocols for patients is challenging. We suggest that health policies and specialized institutions should direct increasing attention on aerobic activity as lifestyle modifiable factor for successful aging and age-related conditions.

Nicotine, THC, and Dolutegravir Modulate E-Cigarette-Induced Changes in Addiction- and Inflammation-Associated Genes in Rat Brains and Astrocytes

E-cigarette use has been marketed as a safer alternative to traditional cigarettes, as a means of smoking cessation, and are used at a higher rate than the general population in people with HIV (PWH). Early growth receptor 2 (EGR2) and Activity-Regulated Cytoskeleton-Associated Protein (ARC) have a role in addiction, synaptic plasticity, inflammation, and neurodegeneration. This study showed that 10 days of exposure to e-cigarette vapor altered gene expression in the brains of 6-month-old, male, Sprague Dawley rats. Specifically, the e-cigarette solvent vapor propylene glycol (PG) downregulated EGR2 and ARC mRNA expression in frontal cortex, an effect which was reversed by nicotine (NIC) and THC, suggesting that PG could have a protective role against NIC and cannabis dependence. However, in vitro, PG upregulated EGR2 and ARC mRNA expression at 18 h in cultured C6 rat astrocytes suggesting that PG may have neuroinflammatory effects. PG-induced upregulation of EGR2 and ARC mRNA was reversed by NIC but not THC. The HIV antiretroviral DTG reversed the effect NIC had on decreasing PG-induced upregulation of EGR2, which is concerning because EGR2 has been implicated in HIV latency reversal, T-cell apoptosis, and neuroinflammation, a process that underlies the development of HIV-associated neurocognitive disorders.

Subsequent maternal sleep deprivation aggravates neurobehavioral abnormalities, inflammation, and synaptic function in adult male mice exposed to prenatal inflammation

OBJECTIVE

Studies have suggested that prenatal exposure to inflammation increases the risk of neuropsychiatric disorders, including anxiety, depression, and cognitive dysfunction. Because of anatomical and hormonal alterations, pregnant women frequently experience sleep dysfunction, which can enhance the inflammatory response. The aim of this study was to explore the effects of maternal sleep deprivation on prenatal inflammation exposure-induced behavioral phenotypes in offspring and identify the associated mechanisms.

METHODS

Pregnant mice received an intraperitoneal injection of lipopolysaccharide (LPS) on gestational day 15 and were subsequently subjected to sleep deprivation during gestational days 15-21. Anxiety-like behavior was evaluated by the open field test and the elevated plus maze test. Depression-like behavior was assessed by the tail suspension test and the forced swimming test. Cognitive function was determined using the Morris water maze test. The levels of markers of inflammation and synaptic function were examined employing general molecular biological techniques.

RESULTS

The results showed that prenatal exposure to LPS resulted in anxiety- and depression-like symptoms and learning and memory deficits, and these effects were exacerbated by maternal sleep deprivation. Furthermore, maternal sleep deprivation aggravated the prenatal LPS exposure-induced increase in the expression of interleukin (IL)-1β, IL-6, and tumor necrosis factor-α and decrease in the levels of postsynaptic density-95 and synaptophysin in the hippocampus.

DISCUSSION

Collectively, these results suggested that maternal sleep deprivation exacerbates anxiety, depression, and cognitive impairment induced by prenatal LPS exposure, effects that were associated with an inflammatory response and synaptic dysfunction.

Environmental Enrichment Protects against Neurotoxic Effects of Lipopolysaccharide: A Comprehensive Overview

Neuroinflammation is a pathophysiological condition associated with damage to the nervous system. Maternal immune activation and early immune activation have adverse effects on the development of the nervous system and cognitive functions. Neuroinflammation during adulthood leads to neurodegenerative diseases. Lipopolysaccharide (LPS) is used in preclinical research to mimic neurotoxic effects leading to systemic inflammation. Environmental enrichment (EE) has been reported to cause a wide range of beneficial changes in the brain. Based on the above, the purpose of the present review is to describe the effects of exposure to EE paradigms in counteracting LPS-induced neuroinflammation throughout the lifespan. Up to October 2022, a methodical search of studies in the literature, using the PubMed and Scopus databases, was performed, focusing on exposure to LPS, as an inflammatory mediator, and to EE paradigms in preclinical murine models. On the basis of the inclusion criteria, 22 articles were considered and analyzed in the present review. EE exerts sex- and age-dependent neuroprotective and therapeutic effects in animals exposed to the neurotoxic action of LPS. EE’s beneficial effects are present throughout the various ages of life. A healthy lifestyle and stimulating environments are essential to counteract the damages induced by neurotoxic exposure to LPS.

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.

Altered cognition and anxiety in adolescent offspring whose mothers underwent different-pattern maternal sleep deprivation, and cognition link to hippocampal expressions of Bdnf and Syt-1

Background

Inadequate sleep during pregnancy negatively affects the neural development of offspring. Previous studies have focused on the continuous sleep deprivation (CSD) paradigm, but the sleep pattern during late pregnancy is usually fragmented.

Objective

To compare the effects of CSD and fragmented sleep deprivation (FSD) in late pregnancy on emotion, cognition, and expression of synaptic plasticity-related proteins in offspring mice.

Methods

Pregnant CD-1 mice were either subjected to 3/6 h of CSD/FSD during gestation days 15-21, while those in the control group were left untreated. After delivery, the offspring were divided into five groups, i.e., control (CON), short or long CSD (CSD3h, CSD6h), and short or long FSD (FSD3h, FSD6h). When the offspring were 2 months old, the anxiety-like behavior level was tested using the open field (OF) and elevated plus maze (EPM) test, and spatial learning and memory were evaluated using the Morris water maze (MWM) test. The expression of hippocampal of brain-derived neurotrophic factor (Bdnf) and synaptotagmin-1 (Syt-1) was determined using RT-PCR and western blotting.

Results

The CSD6h, FSD3h, and FSD6h had longer latency, fewer center times in the OF test, less open arms time and fewer numbers of entries in the open arms of the EPM, longer learning distance swam and lower memory percentage of distance swam in the target quadrant in the MWM test, and decreased BDNF and increased Syt-1 mRNA and protein levels in the hippocampus. Compared to the CSD6h, the FSD3h and FSD6h had longer distance swam, a lower percentage of distance swam in the target quadrant, decreased BDNF, and increased Syt-1 mRNA and protein levels in the hippocampus.

Conclusion

The results suggested that maternal sleep deprivation during late pregnancy impairs emotion and cognition in offspring, and FSD worsened the cognitive performance to a higher extent than CSD. The observed cognitive impairment could be associated with the expression of altered hippocampal of Bdnf and Syt-1 genes.

Environmental Enrichment Reverses Maternal Sleep Deprivation-Induced Anxiety-Like Behavior and Cognitive Impairment in CD-1 Mice

Preclinical studies have clearly indicated that offspring of mothers who suffered sleep deprivation during pregnancy exhibit anxiety, depression-like behaviors, and cognitive deficits. The cognitive impairment induced by maternal sleep deprivation (MSD) is currently poorly treated. Growing evidence indicates that an enriched environment (EE) improves cognition function in models of Alzheimer’s disease, schizophrenia, and lipopolysaccharide. However, the effects of EE on hippocampal-dependent learning and memory, as well as synaptic plasticity markers changes induced by MSD, are unclear. In the present study, pregnant CD-1 mice were randomly divided into a control group, MSD group, and MSD+EE group. Two different living environments, including standard environment and EE, were prepared. When male and female offspring were 2 months, the open field test and elevated plus maze were used to assess anxiety-like behavior, and the Morris water maze was used to evaluate hippocampal learning and memory. Western blotting and real-time fluorescence quantitative polymerase chain reaction were used to detect the expression of brain-derived neurotrophic factor and Synaptotagmin-1 in the hippocampus of offspring. The results revealed that MSD-induced offspring showed anxiety-like behaviors and cognitive impairment, while EE alleviated anxiety-like behavior and cognitive impairment in offspring of the MSD+EE group. The cognitive impairment induced by MSD was associated with a decreased brain-derived neurotrophic factor and an increased Synaptotagmin-1, while EE increased and decreased brain-derived neurotrophic factor and Synaptotagmin-1 in the hippocampus of mice from the MSD+EE group, respectively. Taken together, we can conclude that EE has beneficial effects on MSD-induced synaptic plasticity markers changes and can alleviate anxiety-like behaviors and cognitive impairment.