Pre- and Post-natal High Fat Feeding Differentially Affects the Structure and Integrity of the Neurovascular Unit of 16-Month Old Male and Female Mice

Cannabidiol improves maternal obesity-induced behavioral, neuroinflammatory and neurochemical dysfunctions in the juvenile offspring

Maternal obesity is associated with an increased risk of psychiatric disorders such as anxiety, depression, schizophrenia and autism spectrum disorder in the offspring. While numerous studies focus on preventive measures targeting the mothers, only a limited number provide practical approaches for addressing the damages once they are already established. We have recently demonstrated the interplay between maternal obesity and treatment with cannabidiol (CBD) on hypothalamic inflammation and metabolic disturbances, however, little is known about this relationship on behavioral manifestations and neurochemical imbalances in other brain regions. Therefore, here we tested whether CBD treatment could mitigate anxiety-like and social behavioral alterations, as well as neurochemical disruptions in both male and female offspring of obese dams. Female Wistar rats were fed a cafeteria diet for 12 weeks prior to mating, and during gestation and lactation. Offspring received CBD (50 mg/kg) from weaning for 3 weeks. Behavioral tests assessed anxiety-like manifestations and social behavior, while neuroinflammatory and neurochemical markers were evaluated in the prefrontal cortex (PFC) and hippocampus. CBD treatment attenuated maternal obesity-induced anxiety-like and social behavioral alterations, followed by rescuing effects on imbalanced neurotransmitter and endocannabinoid concentrations and altered expression of glial markers, CB1, oxytocin and dopamine receptors, with important differences between sexes. Overall, the findings of this study provide insight into the signaling pathways for the therapeutic benefits of CBD on neuroinflammation and neurochemical imbalances caused by perinatal maternal obesity in the PFC and the hippocampus, which translates into the behavioral manifestations, highlighting the sexual dimorphism encompassing both the transgenerational effect of obesity and the endocannabinoid system.

Linking peripheral atherosclerosis to blood-brain barrier disruption: elucidating its role as a manifestation of cerebral small vessel disease in vascular cognitive impairment

Aging plays a pivotal role in the pathogenesis of cerebral small vessel disease (CSVD), contributing to the onset and progression of vascular cognitive impairment and dementia (VCID). In older adults, CSVD often leads to significant pathological outcomes, including blood-brain barrier (BBB) disruption, which in turn triggers neuroinflammation and white matter damage. This damage is frequently observed as white matter hyperintensities (WMHs) in neuroimaging studies. There is mounting evidence that older adults with atherosclerotic vascular diseases, such as peripheral artery disease, ischemic heart disease, and carotid artery stenosis, face a heightened risk of developing CSVD and VCID. This review explores the complex relationship between peripheral atherosclerosis, the pathogenesis of CSVD, and BBB disruption. It explores the continuum of vascular aging, emphasizing the shared pathomechanisms that underlie atherosclerosis in large arteries and BBB disruption in the cerebral microcirculation, exacerbating both CSVD and VCID. By reviewing current evidence, this paper discusses the impact of endothelial dysfunction, cellular senescence, inflammation, and oxidative stress on vascular and neurovascular health. This review aims to enhance understanding of these complex interactions and advocate for integrated approaches to manage vascular health, thereby mitigating the risk and progression of CSVD and VCID.

Immune Alterations in the Intrauterine Environment Shape Offspring Brain Development in a Sex-Specific Manner

Exposure to immune dysregulation in utero or in early life has been shown to increase risk for neuropsychiatric illness. The sources of inflammation can be varied, including acute exposures due to maternal infection or acute stress, or persistent exposures due to chronic stress, obesity, malnutrition, or autoimmune diseases. These exposures may cause subtle alteration in brain development, structure, and function that can become progressively magnified across the life span, potentially increasing the likelihood of developing a neuropsychiatric conditions. There is some evidence that males are more susceptible to early-life inflammatory challenges than females. In this review, we discuss the various sources of in utero or early-life immune alteration and the known effects on fetal development with a sex-specific lens. To do so, we leveraged neuroimaging, behavioral, cellular, and neurochemical findings. Gaining clarity about how the intrauterine environment affects offspring development is critically important for informing preventive and early intervention measures that may buffer against the effects of these early-life risk factors.

Long-term impact of maternal obesity on the gliovascular unit and ephrin signaling in the hippocampus of adult offspring

BACKGROUND

Children born to obese mothers are at increased risk of developing mood disorders and cognitive impairment. Experimental studies have reported structural changes in the brain such as the gliovascular unit as well as activation of neuroinflammatory cells as a part of neuroinflammation processing in aged offspring of obese mothers. However, the molecular mechanisms linking maternal obesity to poor neurodevelopmental outcomes are not well established. The ephrin system plays a major role in a variety of cellular processes including cell-cell interaction, synaptic plasticity, and long-term potentiation. Therefore, in this study we determined the impact of maternal obesity in pregnancy on cortical, hippocampal development, vasculature and ephrin-A3/EphA4-signaling, in the adult offspring in mice.

METHODS

Maternal obesity was induced in mice by a high fat/high sugar Western type of diet (HF/HS). We collected brain tissue (prefrontal cortex and hippocampus) from 6-month-old offspring of obese and lean (control) dams. Hippocampal volume, cortical thickness, myelination of white matter, density of astrocytes and microglia in relation to their activity were analyzed using 3-D stereological quantification. mRNA expression of ephrin-A3, EphA4 and synaptic markers were measured by qPCR in the brain tissue. Moreover, expression of gap junction protein connexin-43, lipocalin-2, and vascular CD31/Aquaporin 4 were determined in the hippocampus by immunohistochemistry.

RESULTS

Volume of hippocampus and cortical thickness were significantly smaller, and myelination impaired, while mRNA levels of hippocampal EphA4 and post-synaptic density (PSD) 95 were significantly lower in the hippocampus in the offspring of obese dams as compared to offspring of controls. Further analysis of the hippocampal gliovascular unit indicated higher coverage of capillaries by astrocytic end-feet, expression of connexin-43 and lipocalin-2 in endothelial cells in the offspring of obese dams. In addition, offspring of obese dams demonstrated activation of microglia together with higher density of cells, while astrocyte cell density was lower.

CONCLUSION

Maternal obesity affects brain size, impairs myelination, disrupts the hippocampal gliovascular unit and decreases the mRNA expression of EphA4 and PSD-95 in the hippocampus of adult offspring. These results indicate that the vasculature-glia cross-talk may be an important mediator of altered synaptic plasticity, which could be a link between maternal obesity and neurodevelopmental/neuropsychiatric disorders in the offspring.

Metabolic control of puberty: 60 years in the footsteps of Kennedy and Mitra's seminal work

An individual's nutritional status has a powerful effect on sexual maturation. Puberty onset is delayed in response to chronic energy insufficiency and is advanced under energy abundance. The consequences of altered pubertal timing for human health are profound. Late puberty increases the chances of cardiometabolic, musculoskeletal and neurocognitive disorders, whereas early puberty is associated with increased risks of adult obesity, type 2 diabetes mellitus, cardiovascular diseases and various cancers, such as breast, endometrial and prostate cancer. Kennedy and Mitra's trailblazing studies, published in 1963 and using experimental models, were the first to demonstrate that nutrition is a key factor in puberty onset. Building on this work, the field has advanced substantially in the past decade, which is largely due to the impressive development of molecular tools for experimentation and population genetics. In this Review, we discuss the latest advances in basic and translational sciences underlying the nutritional and metabolic control of pubertal development, with a focus on perspectives and future directions.

Appetitive Motivation and Associated Neurobiology Change Differentially across the Life Course of Mouse Offspring Exposed to Peri- and Postnatal High Fat Feeding

Alterations in neural pathways that regulate appetitive motivation may contribute to increased obesity risk in offspring born to mothers fed a high fat (HF) diet. However, current findings on the impact of maternal obesity on motivation in offspring are inconclusive, and there is no information about the long-lasting effects in aged animals. This study examined the longitudinal effect of perinatal and chronic postnatal HF intake on appetitive motivation in young and aged offspring. Female C57Bl/6 were fed either a control (C) or HF diet before mating through to lactation. At weaning, offspring were maintained on the C or HF diet, generating the following four diet groups: C/C, C/HF, HF/C, and HF/HF based on the pre/post weaning diet. At 6 months, motivation was higher in HF/C females, but lower in male and female C/HF and HF/HF mice. By 12 months, this difference was lost, as C-fed animals became less motivated, while motivation increased in HF-fed mice. The mRNA levels of dopamine receptor 1 and 2 increased with age, while cannabinoid receptor 1 and μ-opioid receptor expression remained stable or decreased in mesolimbic and mesocortical dopaminergic pathways. Results from this study suggest that perinatal and chronic postnatal HF feeding produced opposite effects on appetitive motivation in young adult offspring mice, which was also reflected in the shift in motivation over time. These results have significant implications for patterns of hedonic eating across the life course and the relative risk of obesity at different time points.

α-Dystrobrevin knockout mice have increased motivation for appetitive reward and altered brain cannabinoid receptor 1 expression

α-Dystrobrevin (α-DB) is a major component of the dystrophin-associated protein complex (DAPC). Knockout (KO) of α-DB in the brain is associated with astrocytic abnormalities and loss of neuronal GABA receptor clustering. Mutations in DAPC proteins are associated with altered dopamine signaling and cognitive and psychiatric disorders, including schizophrenia. This study tested the hypothesis that motivation and associated underlying biological pathways are altered in the absence of α-DB expression. Male wildtype and α-DB KO mice were tested for measures of motivation, executive function and extinction in the rodent touchscreen apparatus. Subsequently, brain tissues were evaluated for mRNA and/or protein levels of dysbindin-1, dopamine transporter and receptor 1 and 2, mu opioid receptor 1 (mOR1) and cannabinoid receptor 1 (CB1). α-DB KO mice had significantly increased motivation for the appetitive reward, while measures of executive function and extinction were unaffected. No differences were observed between wildtype and KO animals on mRNA levels of dysbindin-1 or any of the dopamine markers. mRNA levels of mOR1were significantly decreased in the caudate-putamen and nucleus accumbens of α-DB KO compared to WT animals, but protein levels were unaltered. However, CB1 protein levels were significantly increased in the prefrontal cortex and decreased in the nucleus accumbens of α-DB KO mice. Triple-labelling immunohistochemistry confirmed that changes in CB1 were not specific to astrocytes. These results highlight a novel role for α-DB in the regulation of appetitive motivation that may have implications for other behaviours that involve the dopaminergic and endocannabinoid systems.

Dietary fat: a potent microglial influencer

Poor nutrition, lack of exercise, and genetic predisposition all contribute to the growing epidemic of obesity. Overweight/obesity create an environment of chronic inflammation that leads to negative physiological and neurological outcomes, such as diabetes, cardiovascular disease, and anxiety/depression. While the whole body contributes to metabolic homeostasis, the neuroimmune system has recently emerged as a key regulator of metabolism. Microglia, the resident immune cells of the brain, respond both directly and indirectly to dietary fat, and the environment in which microglia develop contributes to their responsiveness later in life. Thus, high maternal weight during pregnancy may have consequences for microglial function in offspring. Here, we discuss the most recent findings on microglia signaling in overweight/obesity with a focus on perinatal programming.

Effects of maternal diet-induced obesity on metabolic disorders and age-associated miRNA expression in the liver of male mouse offspring

OBJECTIVE

This study investigated the effect of maternal obesity on aged-male offspring liver phenotype and hepatic expression of a programmed miRNA.

METHODS

A mouse model (C57BL/6 J) of maternal diet-induced obesity was used to investigate fasting-serum metabolites, hepatic lipid content, steatosis, and relative mRNA levels (RT-PCR) and protein expression (Western blotting) of key components involved in hepatic and mitochondrial metabolism in 12-month-old offspring. We also measured hepatic lipid peroxidation, mitochondrial content, fibrosis stage, and apoptosis in the offspring. To investigate potential mechanisms leading to the observed phenotype, we also measured the expression of miR-582 (a miRNA previously implicated in liver cirrhosis) in 8-week-old and 12-month-old offspring.

RESULTS

Body weight and composition was similar between 8-week-old offspring, however, 12-month-old offspring from obese mothers had increased body weight and fat mass (19.5 ± 0.8 g versus 10.4 ± 0.9 g, p < 0.001), as well as elevated serum levels of LDL and leptin and hepatic lipid content (21.4 ± 2.1 g versus 12.9 ± 1.8 g, p < 0.01). This was accompanied by steatosis, increased Bax/Bcl-2 ratio, and overexpression of p-SAPK/JNK, Tgfβ1, Map3k14, and Col1a1 in the liver. Decreased levels of Bcl-2, p-AMPKα, total AMPKα and mitochondrial complexes were also observed. Maternal obesity was associated with increased hepatic miR-582-3p (p < 0.001) and miR-582-5p (p < 0.05). Age was also associated with an increase in both miR-582-3p and miR-582-5p, however, this was more pronounced in the offspring of obese dams, such that differences were greater in 12-month-old animals (-3p: 7.34 ± 1.35 versus 1.39 ± 0.50, p < 0.0001 and -5p: 4.66 ± 1.16 versus 1.63 ± 0.65, p < 0.05).

CONCLUSION

Our findings demonstrate that maternal diet-induced obesity has detrimental effects on offspring body composition as well as hepatic phenotype that may be indicative of accelerated-ageing phenotype. These whole-body and cellular phenotypes were associated with age-dependent changes in expression of miRNA-582 that might contribute mechanistically to the development of metabolic disorders in the older progeny.

Maternal high-fat diet in mice induces cerebrovascular, microglial and long-term behavioural alterations in offspring

Various environmental exposures during pregnancy, like maternal diet, can compromise, at critical periods of development, the neurovascular maturation of the offspring. Foetal exposure to maternal high-fat diet (mHFD), common to Western societies, has been shown to disturb neurovascular development in neonates and long-term permeability of the neurovasculature. Nevertheless, the effects of mHFD on the offspring’s cerebrovascular health remains largely elusive. Here, we sought to address this knowledge gap by using a translational mouse model of mHFD exposure. Three-dimensional and ultrastructure analysis of the neurovascular unit (vasculature and parenchymal cells) in mHFD-exposed offspring revealed major alterations of the neurovascular organization and metabolism. These alterations were accompanied by changes in the expression of genes involved in metabolism and immunity, indicating that neurovascular changes may result from abnormal brain metabolism and immune regulation. In addition, mHFD-exposed offspring showed persisting behavioural alterations reminiscent of neurodevelopmental disorders, specifically an increase in stereotyped and repetitive behaviours into adulthood.

In order to advance our understanding of the effects of maternal high-fat diet (mHFD) on the cerebrovascular health of offspring, Bordeleau et al. use a translational mouse model of mHFD exposure. They demonstrate that mHFD induces cerebrovascular and microglial changes in the offspring as well as behavioural alterations that are reminiscent of neurodevelopmental disorders associated with repetitive behaviours at adulthood.

The impact of maternal obesity on childhood neurodevelopment

There is growing clinical and experimental evidence to suggest that maternal obesity increases children's susceptibility to neurodevelopmental and neuropsychiatric disorders. Given the worldwide obesity epidemic, it is crucial that we acquire a thorough understanding of the available evidence, identify gaps in knowledge, and develop an agenda for intervention. This review synthesizes human and animal studies investigating the association between maternal obesity and offspring brain health. It also highlights key mechanisms underlying these effects, including maternal and fetal inflammation, alterations to the microbiome, epigenetic modifications of neurotrophic genes, and impaired dopaminergic and serotonergic signaling. Lastly, this review highlights several proposed interventions and priorities for future investigation.

An Eclectic Cast of Cellular Actors Orchestrates Innate Immune Responses in the Mechanisms Driving Obesity and Metabolic Perturbation

The escalating problem of obesity and its multiple metabolic and cardiovascular complications threatens the health and longevity of humans throughout the world. The cause of obesity and one of its chief complications, insulin resistance, involves the participation of multiple distinct organs and cell types. From the brain to the periphery, cell-intrinsic and intercellular networks converge to stimulate and propagate increases in body mass and adiposity, as well as disturbances of insulin sensitivity. This review focuses on the roles of the cadre of innate immune cells, both those that are resident in metabolic organs and those that are recruited into these organs in response to cues elicited by stressors such as overnutrition and reduced physical activity. Beyond the typical cast of innate immune characters invoked in the mechanisms of metabolic perturbation in these settings, such as neutrophils and monocytes/macrophages, these actors are joined by bone marrow-derived cells, such as eosinophils and mast cells and the intriguing innate lymphoid cells, which are present in the circulation and in metabolic organ depots. Upon high-fat feeding or reduced physical activity, phenotypic modulation of the cast of plastic innate immune cells ensues, leading to the production of mediators that affect inflammation, lipid handling, and metabolic signaling. Furthermore, their consequent interactions with adaptive immune cells, including myriad T-cell and B-cell subsets, compound these complexities. Notably, many of these innate immune cell-elicited signals in overnutrition may be modulated by weight loss, such as that induced by bariatric surgery. Recently, exciting insights into the biology and pathobiology of these cell type-specific niches are being uncovered by state-of-the-art techniques such as single-cell RNA-sequencing. This review considers the evolution of this field of research on innate immunity in obesity and metabolic perturbation, as well as future directions.