Spatial learning and memory deficits induced by prenatal glucocorticoid exposure depend on hippocampal CRHR1 and CXCL5 signaling in rats

Lycium barbarum polysaccharide ameliorates corticosterone-induced cognition decline with modulation of CRHR1

BACKGROUND

Lycium barbarum polysaccharide (LBP) has anti-inflammatory, anti-oxidation and anti-aging properties, but the mechanism of LBP on stress-induced cognitive dysfunction caused by elevated GC level is still unclear.

OBJECTIVES

Therefore, the present study aimed to investigate the mechanism of LBP on corticosterone-injected（CORT-injected） cognitive impairment.

METHODS

The rat model was induced by corticosterone in vivo. Water maze test and HE staining were used to observe the effect of LBP on cognitive function and brain morphology in CORT-injected rats. RT-qPCR, Western blot, and immunofluorescence were used to detect the expression of proteins. SH-SY5Y cells were treated with CORT and D-gal in vitro, respectively. The effect of LBP on cell proliferation was observed, and western blotting was detected in the protein expressions.

RESULTS

In this study, LBP treatment ameliorated CORT-induced learning and cognitive function and protected hypothalamic and hippocampal neurons from injury in vivo. In addition, LBP reduced plasma corticosterone concentrations in CORT-injected rats. The results also indicated that LBP enhanced the expression of synapsis-related proteins PSD95 and SYN by up-regulating the expression of CRHR1 and RGS2 in the hippocampus and hypothalamus of the model group. Meanwhile, we confirmed that LBP enhanced CORT - and D-Gal-induced proliferation of SH-SY5Y cells in vitro, and further verified the expression changes of CRHR1, RGS2, and synapse-related proteins.

CONCLUSIONS

This study demonstrates that LBP ameliorated CORT-induced cognition decline by regulating CRHR1. Therefore, LBP may represent a potential drug for the prevention of cognition dysfunction in patients caused by increased GCs.

Uncovering the intricacies of O-GlcNAc modification in cognitive impairment: New insights from regulation to therapeutic targeting

O-linked β-N-acetylglucosamine (O-GlcNAc) represents a post-translational modification that occurs on serine or threonine residues on various proteins. This conserved modification interacts with vital cellular pathways. Although O-GlcNAc is widely distributed throughout the body, it is particularly enriched in the brain, where most proteins are O-GlcNAcylated. Recent studies have established a causal link between O-GlcNAc regulation in the brain and alterations in neurophysiological function. Alterations in O-GlcNAc levels in the brain are associated with the pathogenesis of several neurogenic diseases that can lead to cognitive impairment. Remarkably, manipulation of O-GlcNAc levels demonstrated a protective effect on cognitive function. Although the precise molecular mechanism of O-GlcNAc modification in the nervous system remains elusive, its regulation is fundamental to multiple neural and cognitive functions, fluctuating levels during normal and pathological cognitive processes. In this review, we highlight the significant functional importance of O-GlcNAc modification in pathological cognitive impairments and the potential application of O-GlcNAc as a promising target for the intervention or amelioration of cognitive impairments.

Effects of Prenatal Dexamethasone Treatment and Post-Weaning Moderate Fructose Intake on Synaptic Plasticity and Behavior in Adult Male Wistar Rat Offspring

Early-life glucocorticoid overexposure induces diverse neurodevelopmental outcomes regarding stress reactivity and cognition. Increased fructose consumption has also been associated with alterations in cognitive capacity and behavior. The present study investigated the effects of prenatal dexamethasone exposure on synaptic plasticity, locomotion, anxiety, and recognition memory in adult male Wistar rat offspring, and whether these effects are potentiated by postnatal fructose consumption. Pregnant female rats were treated with dexamethasone during late gestation and male offspring were supplemented with a moderate dose of fructose. Recognition memory, locomotion, and anxiety-like behavior were assessed using a novel object recognition test, open-field test, and elevated plus maze, respectively. Hippocampal synaptic plasticity was estimated by the levels of growth-associated protein 43 (GAP-43), synaptophysin, postsynaptic density protein 95, calcium/calmodulin-dependent kinase IIα, and their activating phosphorylations. Additionally, protein levels of the glucocorticoid receptor (GR) and its transcriptionally active phosphorylated form were evaluated. Prenatal dexamethasone treatment induced an anxiolytic-like effect, stimulation of exploratory behavior, and novelty preference associated with an increase in GR and GAP-43 protein levels in the hippocampus. Fructose overconsumption after weaning did not modify the effects of prenatal glucocorticoid exposure. Applied prenatal dexamethasone treatment may induce changes in reactions to novel situations in male Wistar rats.

Dissecting the networks underlying diverse brain disorders after prenatal glucocorticoid overexposure

New human life begins in the uterus in a period of both extreme plasticity and sensitivity to environmental disturbances. The fetal stage is also a vital period for central nervous system development, with experiences at this point profoundly and permanently shaping brain structure and function. As such, some brain disorders may originate in utero. Glucocorticoids, a class of essential stress hormones, play indispensable roles in fetal development, but overexposure may have lasting impacts on the brain. In this review, we summarize data from recent clinical and non-clinical studies regarding alterations in fetal brains due to prenatal glucocorticoid overexposure that are associated with nervous system disorders. We discuss relevant changes to brain structure and cellular functions and explore the underlying molecular mechanisms. In addition, we summarize factors that may cause differential outcomes between varying brain regions, and outline clinically feasible intervention strategies that are expected to minimize negative consequences arising from fetal glucocorticoid overexposure. Finally, we highlight the need for experimental evidence aided by new technologies to clearly determine the effects of excessive prenatal glucocorticoid exposure. This review consolidates diverse findings to help researchers better understand the relationship between the prenatal glucocorticoid overexposure and the effects it has on various fetal brain regions, promoting further development of critical intervention strategies.

Manganese disrupts the maturation and degradation of axonal autophagosome leading to hippocampal synaptic toxicity in mice via the activation of LRRK2 on phosphorylation of Rab10

Manganese (Mn) overexposure induces hippocampal synaptotoxicity by the accumulation of dysfunctional synaptic vesicles (SVs). Leucine-rich repeat kinase 2 (LRRK2) kinase activity is involved in regulating axonal transport (autophagosomal maturation) and lysosomal function. Nevertheless, it remains unclear whether Mn-induced synaptotoxicity is associated with the LRRK2-mediated disruption of autophagosomal maturation in axonal transport and the impairment of lysosomes in hippocampal neurons. Here, we established models of manganism in C57BL/6 mice and hippocampal neuronal HT22 cells to verify the role of LRRK2-mediated Rab10 phosphorylation in the Mn-induced dysfunction of autophagy- lysosomal fusion. Our results proved that Mn-induced the disorder of axonal transport and that lysosome impairments were associated with the increased recruitment of phospho-Rab10 at the axon and lysosomes. Next, we established Lrrk2-KD and LRRK2 kinase- specific inhibitor (GNE-0877, GNE) pre-treated HT22 cells to inhibit Lrrk2 gene expression and kinase activity, respectively. In Mn-treated Lrrk2-KD or GNE-pretreated normal neurons, our results indicated that lysosomal pH and integrity and autophagic flow were restored, indicating by decreased levels of phospho-Rab10 on lysosomes and JNK-interacting proteins (JIP4). In addition, GNE pretreatment could provide protection against Mn-induced synaptotoxicity in vivo, which was evidenced by the partial recovery in synaptic plasticity and synaptic damage. Thus, the Mn-induced abnormal activation of LRRK2 affected lysosomes and the recruitment of phospho-Rab10 by JIP4, which disrupted autophagosomal maturation in proximal axons and resulted in the hippocampal synaptic toxicity of mice.

GR/Ahi1 regulates WDR68-DYRK1A binding and mediates cognitive impairment in prenatally stressed offspring

Accumulating research shows that prenatal exposure to maternal stress increases the risk of behavioral and mental health problems for offspring later in life. However, how prenatal stress affects offspring behavior remains unknown. Here, we found that prenatal stress (PNS) leads to reduced Ahi1, decreased synaptic plasticity and cognitive impairment in offspring. Mechanistically, Ahi1 and GR stabilize each other, inhibit GR nuclear translocation, promote Ahi1 and WDR68 binding, and inhibit DYRK1A and WDR68 binding. When Ahi1 deletion or prenatal stress leads to hyperactivity of the HPA axis, it promotes the release of GC, leading to GR nuclear translocation and Ahi1 degradation, which further inhibits the binding of Ahi1 and WDR68, and promotes the binding of DYRK1A and WDR68, leading to elevated DYRK1A, reduced synaptic plasticity, and cognitive impairment. Interestingly, we identified RU486, an antagonist of GR, which increased Ahi1/GR levels and improved cognitive impairment and synaptic plasticity in PNS offspring. Our study contributes to understanding the signaling mechanisms of prenatal stress-mediated cognitive impairment in offspring.

Effects and mechanisms of salidroside on the behavior of SPS-induced PTSD rats

Post-traumatic stress disorder (PTSD) is a complex mental disorder, closely associated with stress and traumatic events. Salidroside (Sal) has been reported to possess neuroprotective effects. However, the behavioral effects and mechanisms of Sal on PTSD remain unknown. In this study, we utilized a rat model of PTSD induced by single prolonged stress (SPS) and administered Sal intraperitoneally (25, 50, 75 mg/kg/d) for 14 days. We then examined the behavioral effects and underlying mechanisms of Sal on SPS-induced PTSD rats. Our findings demonstrated that Sal alleviated anxiety-like behavior and spatial learning and memory impairment in SPS-induced PTSD rats. Furthermore, Sal treatment preserved the histomorphology of the hippocampal region. It was observed that Sal protected against hippocampal neuronal apoptosis in PTSD rats by reducing the number of TUNEL-positive cells and modulating apoptosis-related proteins (Bcl-2 and Bax). Additionally, Sal inhibited the activation of the NF-κB/iNOS/COX-2 signaling pathway in the hippocampus of PTSD rats, thereby suppressing the release of inflammatory factors (TNF-α and IL-1β) and the activation of microglia. Notably, Sal increased the expression of synapse-associated proteins PSD95 and Synapsin I in the hippocampus, while also enhancing dendritic density in the region. In conclusion, our results demonstrated that Sal could attenuate SPS-induced PTSD-like behaviors by inhibiting hippocampal neuronal apoptosis, enhancing hippocampal synaptic plasticity, and reducing neuroinflammatory responses. These findings may provide a foundation for the potential clinical application of Sal in the treatment of PTSD.

Impact of Prenatal Acetaminophen Exposure for Hippocampal Development Disorder on Mice

Non-steroidal anti-inflammatory drugs (NSAIDs) are widely used as analgesic agents. They have been detected in various environmental matrices. The degradation of environmental contaminants and the long-term adverse effects have become a major public concern. Prenatal exposure to acetaminophen can cause damage to the developing hippocampus. However, the molecular mechanisms behind hippocampal damage following prenatal acetaminophen exposure (PAcE) remain unclear. The present study shows an increased risk of adverse neurodevelopmental outcomes in offspring following exposure to acetaminophen during pregnancy on mice. The results revealed that different doses, timings, and duration of exposure to acetaminophen during pregnancy were associated with dose-dependent changes in the hippocampus of the offspring. Furthermore, exposure to high doses, multiple-treatment courses, and late pregnancy induced pathological changes, such as wrinkling and vacuolation, inhibited hippocampal proliferation and increased apoptosis. In addition, PAcE significantly decreased the expression of genes related to synaptic development in fetal hippocampal neurons and hippocampal astrocyte and microglia were also damaged to varying degrees. The significant reduction either in SOX2, an essential gene in regulating neural progenitor cell proliferation, and reduction of genes related to the SOX2/Notch pathway may suggest that the role of SOX2/Notch pathway in impaired hippocampal development in the offspring due to PAcE. In general, PAcE at high doses, multiple-treatment courses, and mid- and late gestation were associated with neurodevelopmental toxicity to the offspring.

Amniotic fluid cortisol predicts neonatal and infant development in non-stressed rhesus monkeys: Implications for prenatal stress

Prenatal stress adversely affects offspring development, with fetal cortisol (CORT) exposure being a primary hypothesized mechanism for stress-induced developmental deficits. Fetal CORT exposure can be assessed via measurements in amniotic fluid. However, in humans, amniocentesis is typically only performed for clinical reasons such as karyotyping; thus, amniotic fluid CORT cannot be obtained from a random sample. To test the hypothesis that fetal CORT exposure predicts neonatal and infant development in healthy primates, we measured amniotic fluid CORT in N = 18 healthy rhesus macaque (Macaca mulatta) dams (50:50 female:male infants) between 80 and 124 days gestation (mean ± SEM = 98.3 ± 2.9 days out of 165 days gestational length; i.e., second trimester). Maternal hair cortisol concentrations (HCCs) were assessed throughout pregnancy and lactation. Offspring were assessed for physical growth, neurological development, cognitive development, and HCCs across postnatal days 30-180. Controlling for gestational age at amniocentesis, higher amniotic fluid CORT significantly predicted slower infant growth rate (g/day) in the first 30 days (β = -0.19; R2 = 0.71, p = .008), poorer sensorimotor scores on the day 30 neonatal assessment (β = -0.28; R2 = 0.76, p = .015), and longer time to complete training (β = 0.48; R2 = 0.54, p = .026), but better performance (β = 0.91; R2 = 0.60, p = .011) on a discrimination cognitive task at 120-180 days. Amniotic fluid CORT was not associated with maternal or infant HCCs. Although these results are correlative, they raise the intriguing possibility that fetal CORT exposure in non-stress-exposed primates, as measured by amniotic fluid CORT, programs multiple aspects of neonatal and infant development. On the other hand, amniotic fluid CORT may not relate to chronic CORT levels in either mothers or infants when assessed by hair sampling.

A Nanodisc-Paved Biobridge Facilitates Stem Cell Membrane Fusogenicity for Intracerebral Shuttling and Bystander Effects

Mesenchymal stem cell (MSC) therapies experience steadfast clinical advances but are still hindered by inefficient site-specific migration. An adaptable MSC membrane fusogenicity technology is conceptualized for lipid raft-mediated targeting ligand embedding by using toolkits of discoidal high-density lipoprotein (HDL)-containing biomimicking 4F peptides. According to the pathological clues of brain diseases, the vascular cell adhesion molecule 1 specialized VBP peptide is fused with 4F to assemble 4F-VBP (HDL), which acts as a biobridge and transfers VBP onto the living cell membrane via lipid rafts for surface engineering of MSCs in suspension. When compared with the membrane-modifying strategies of PEGylated phospholipids, 4F-VBP (HDL) provides a 3.86 higher linkage efficiency to obtain MSCs4F-VBP(HDL) , which can recognize and adhere to the inflammatory endothelium for efficient blood-brain barrier crossing and brain accumulation. In APPswe/PSEN1dE9 mice with Alzheimer's disease (AD), the transcriptomic analysis reveals that systemic administration of MSCs4F-VBP(HDL) can activate pathways associated with neuronal activity and diminish neuroinflammation for rewiring AD brains. This customizable HDL-mediated membrane fusogenicity platform primes MSC inflammatory brain delivery, which can be expanded to other disease treatments by simply fusing 4F with relevant ligands for living cell engineering.

Sex-specificities in offspring neurodevelopment and behaviour upon maternal glycation: Putative underlying neurometabolic and synaptic changes

AIM

Lactation is an important programming window for metabolic disease and neuronal alterations later in life. We aimed to study the effect of maternal glycation during lactation on offspring neurodevelopment and behaviour, assessing possible sex differences and underpinning molecular players.

METHODS

Female Wistar rats were treated with the Glyoxalase-1 inhibitor S-p-Bromobenzylguthione cyclopentyl diester (BBGC 5 mg/kg). A control and vehicle group treated with dimethyl sulfoxide were considered. Male and female offspring were tested at infancy for neurodevelopment hallmarks. After weaning, triglycerides and total antioxidant capacity were measured in breast milk. At adolescence, offspring were tested for locomotor ability, anxious-like behaviour, and recognition memory. Metabolic parameters were assessed, and the hippocampus and prefrontal cortex were collected for molecular analysis.

KEY FINDINGS

Maternal glycation reduced triglycerides and total antioxidant capacity levels in breast milk. At infancy, both male and female offspring presented an anticipation on the achievement of neurodevelopmental milestones. At adolescence, male offspring exposed to maternal glycation presented hyperlocomotion, whereas offspring of both sexes presented a risk-taking phenotype, accompanied by GABA_A receptor upregulation in the hippocampus. Females also demonstrated GABA_A and PSD-95 changes in prefrontal cortex. Furthermore, lower levels of GLO1 and consequently higher accumulation of AGES were also observed in both male and female offspring hippocampus.

SIGNIFICANCE

Early exposure to maternal glycation induces changes in milk composition leading to neurodevelopment changes at infancy, and sex-specific behavioural and neurometabolic changes at adolescence, further evidencing that lactation period is a critical metabolic programming window and in sculpting behaviour.

Impact of prenatal amoxicillin exposure on hippocampal development deficiency

BACKGROUND

Amoxicillin has been widely used to treat infectious diseases during pregnancy. Current studies suggest that amoxicillin exposure during pregnancy could lead to developmental disorders in the offspring and increase the incidence of long-term complications such as asthma and kidney damage in adulthood. However, the adverse effects of prenatal amoxicillin exposure (PAmE) including administration stage, doses and courses on fetal hippocampal neurodevelopment and its function in the offspring have not been elucidated. In this study, we intend to investigate the effects of PAmE on fetal hippocampal development and its possible mechanisms.

METHOD

Pregnant Kunming mice were given intragastric administration with amoxicillin at different administration stage, doses and courses, and GD (gestational day) 18 offspring hippocampus was collected for morphological and development-related functional assays, and the molecular mechanisms were explored.

RESULTS

PAmE induced hippocampal hypoplasia in the offspring with suppressed hippocampal neuronal cell proliferation and impaired neuronal synaptic plasticity comparatively; hippocampal astrocyte and microglia were damaged to varying degrees. The developmental toxicity of PAmE in fetal mices varies by time, dose, and course of treatment. The most severe damage was observed in the late gestation, high dose, and multi-course dosing groups. The significant reduction either in SOX2, an essential gene in regulating neural progenitor cell proliferation, and reduction of genes related to the Wnt/β-catenin pathway may suggest that the key role of SOX2/Wnt/β-catenin pathway in impaired hippocampal development in the offspring due to PAmE.

CONCLUSION

In this study, PAmE was found to be developmentally toxic to the hippocampus thus to induce developmental damage to various hippocampal cells; Even with current clinically safe doses, potential hippocampal damage to offspring may still present; This study provides a theoretical and experimental basis for guiding the rational usage of drugs during pregnancy and giving effectively assessment of the risk on fetal hippocampal developmental toxicity.

Paternal Nicotine/Ethanol/Caffeine Mixed Exposure Induces Offspring Rat Dysplasia and Its Potential "GC-IGF1" Programming Mechanism

Clinical and animal studies suggest that paternal exposure to adverse environments (bad living habits and chronic stress, etc.) has profound impacts on offspring development; however, the mechanism of paternal disease has not been clarified. In this study, a meta-analysis was first performed to suggest that paternal exposure to nicotine, ethanol, or caffeine is a high-risk factor for adverse pregnancy outcomes. Next, we created a rat model of paternal nicotine/ethanol/caffeine mixed exposure (PME), whereby male Wistar rats were exposed to nicotine (0.1 mg/kg/d), ethanol (0.5 g/kg/d), and caffeine (7.5 mg/kg/d) for 8 weeks continuously, then mated with normal female rats to obtain a fetus (n = 12 for control group, n = 10 for PME group). Then, we analyzed the changes in paternal hypothalamic-pituitary-adrenal (HPA) axis activity, testicular function, pregnancy outcomes, fetal serum metabolic indicators, and multiple organ functions to explore the mechanism from the perspective of chronic stress. Our results demonstrated that PME led to enhanced paternal HPA axis activity, decreased sperm quality, and adverse pregnancy outcomes (stillbirth and absorption, decreased fetal weight and body length, and intrauterine growth retardation), abnormal fetal serum metabolic indicators (corticosterone, glucolipid metabolism, and sex hormones), and fetal multi-organ dysfunction (including hippocampus, adrenal, liver, ossification, and gonads). Furthermore, correlation analysis showed that the increased paternal corticosterone level was closely related to decreased sperm quality, adverse pregnancy outcomes, and abnormal offspring multi-organ function development. Among them, the decreased activity of the glucocorticoid-insulin-like growth factor 1 (GC-IGF1) axis may be the main mechanism of offspring development and multi-organ dysfunction caused by PME. This study explored the impact of common paternal lifestyle in daily life on offspring development, and proposed the GC-IGF1 programming mechanisms of paternal chronic stress-induced offspring dysplasia, which provides a novel insight for exploring the important role of paternal chronic stress in offspring development and guiding a healthy lifestyle for men.