Cognitive impairment following high fat diet consumption is associated with brain inflammation

NIH Toolbox Cognition Battery in Young and Older Adults: Reliability and Relationship to Adiposity and Physical Activity

BACKGROUND AND PURPOSE

Executive function in normal aging may be modulated by body habitus and adiposity, both factors modified by physical therapist prescriptions. This study measured between-day reliability of executive function metrics in young and older individuals and examined associations between cognition, adiposity, and physical activity.

METHODS

Forty-three young and 24 older participants underwent executive function assessment via the National Institutes of Health Toolbox Cognition Battery (Dimensional Change Card Sort, Flanker Inhibitory Control and Attention [Flanker], and List Sorting Working Memory [List Sorting]) at 7-day intervals. Between-day reliability was assessed via intraclass correlation (ICC). Responsiveness was assessed via between-day effect size and Cohen's d. Forward stepwise linear regression examined associations between cognition and age, body mass index, percent body fat, and a self-report measure of physical activity (International Physical Activity Questionnaire Short Form).

RESULTS AND DISCUSSION

Executive function scores were higher for young participants than for older participants (all P < .002), consistent with typical age-related cognitive decline. Reliability of cognitive metrics was higher for older participants (ICC = 0.483-0.917) than for young participants (ICC = 0.386-0.730). Between-day effect sizes were approximately 50% smaller for older participants. Percent body fat significantly correlated with the Flanker Unadjusted Scale (P = .004, R2 = 0.0772). Neither vigorous nor total physical activity correlated with any cognitive metric.

CONCLUSIONS

Older participants demonstrated greater between-day reliability for executive function measures, while young participants showed greater capacity to improve performance upon repeat exposure to a cognitive test (especially Flanker). Percent body fat correlated significantly with Flanker scores, while body mass index (an indirect measure of body fat) did not. Self-reported physical activity did not correlate with executive function. Cognitive response to physical therapist-prescribed exercise is a fertile ground for future research.

Correlation between ketones and mental fatigue in high fat-induced obese and non-obese rats

Obesity, often caused by a diet high in calories and low physical activity, may induce physical fatigue, as experienced via decreased locomotor activity and mental fatigue such as impaired cognition. This study aims to evaluate glucose and ketone levels secondary to high-fat diet (HFD) exposure and signs of physical and mental fatigue. Fifty-four 7-week-old male Sprague Dawley rats (Rattus norvegicus) were assigned to either an HFD (n = 28) or a standard diet (SD; n = 26) for a 6-week period during which body weight, blood glucose, and ketones were measured twice per week. An open field (OF) paradigm was used to measure locomotor activity, while novel object recognition (NOR) test was used as an indicator of cognition. Animals in the HFD group weighed more than SD rats (8.4 g; p < 0.05) starting at Day 11, blood glucose levels were higher in the HFD group versus SD rats (3.9 mg/dl; p < 0.05) beginning in Week 5, and ketones were lower for the HFD versus the SD group throughout the study (0.34 mmol/L on average; p < 0.05). Although there was no significant difference in locomotor activity between the HFD and SD groups (p = 0.12), regardless of diet, higher ketone levels were associated with increased NOR time and ratio between the familiar and novel objects (p < 0.01). Thus, this study provides evidence that an increased level of ketones is associated with greater cognitive performance and a lesser probability of experiencing mental fatigue.

The Impact of Obesity on Microglial Function: Immune, Metabolic and Endocrine Perspectives

Increased life expectancy in combination with modern life style and high prevalence of obesity are important risk factors for development of neurodegenerative diseases. Neuroinflammation is a feature of neurodegenerative diseases, and microglia, the innate immune cells of the brain, are central players in it. The present review discusses the effects of obesity, chronic peripheral inflammation and obesity-associated metabolic and endocrine perturbations, including insulin resistance, dyslipidemia and increased glucocorticoid levels, on microglial function.

Nutrigenomics of Dietary Lipids

Dietary lipids have a major role in nutrition, not only for their fuel value, but also as essential and bioactive nutrients. This narrative review aims to describe the current evidence on nutrigenomic effects of dietary lipids. Firstly, the different chemical and biological properties of fatty acids contained both in plant- and animal-based food are illustrated. A description of lipid bioavailability, bioaccessibility, and lipotoxicity is provided, together with an overview of the modulatory role of lipids as pro- or anti-inflammatory agents. Current findings concerning the metabolic impact of lipids on gene expression, epigenome, and gut microbiome in animal and human studies are summarized. Finally, the effect of the individual’s genetic make-up on lipid metabolism is described. The main goal is to provide an overview about the interaction between dietary lipids and the genome, by identifying and discussing recent scientific evidence, recognizing strengths and weaknesses, to address future investigations and fill the gaps in the current knowledge on metabolic impact of dietary fats on health.

Saponins from Panax japonicus alleviate HFD-induced impaired behaviors through inhibiting NLRP3 inflammasome to upregulate AMPA receptors

Obesity is characterized by a condition of low-grade chronic inflammation that facilitates development of numerous comorbidities and dysregulation of brain homeostasis. It is reported that obesity can lead to behavioral alterations such as cognitive decline and depression-like behaviors both in humans and rodents. Saponins from panax japonicus (SPJ) have been reported to exhibit anti-inflammatory action in mouse model of diet-induced obesity. We evaluated the neuroprotection of SPJ on high fat diet (HFD) induced impaired behaviors such as memory deficit and depressive-like behaviors, and explored the underlying mechanisms. 6-week male Balb/c mice were divided into normal control group (NC, 17% total calories from fat), HFD group (60% total calories from fat), and HFD treated with SPJ groups (orally gavaged with dosages of 15 mg/kg and 45 mg/kg), respectively. After treatment for 16 weeks, behavioral tests were performed to evaluate the cognition and depression-like behaviors of the mice. The underling mechanisms of SPJ on HFD-induced impaired behaviors were investigated through histopathological observation, Western blot analysis and immunofluorescence. Our results showed that HFD-fed mice caused behavioral disorders, neuronal degeneration as well as elevated neuroinflammation, which was partly involved in NLRP3 inflammasome that finally resulted in decreased protein levels of AMPA receptors and down-regulated phosphorylated levels of CaMKII and CREB in cortex and hippocampus. All the above changes in cortex and hippocampus induced by HFD were mitigated by SPJ treatment. SPJ treatment alleviated HFD-induced recognitive impairment and depression-like behaviors of mice, which could be partly due to the capacity of SPJ to mitigate neuroinflammation through inhibition of NLRP3 inflammasome and upregulation of AMPA receptors signaling pathway.

Blood lipid markers are associated with hippocampal viscoelastic properties and memory in humans

Age-related memory loss shares similar risk factors as cardiometabolic diseases including elevated serum triglycerides (TGs) and low-density lipoprotein cholesterol (LDL-C) and reduced high-density lipoprotein cholesterol (HDL-C). The mechanisms linking these aberrant blood lipids to memory loss are not completely understood but may be partially mediated by reduced integrity of the hippocampus (HC), the primary brain structure for encoding and recalling memories. In this study, we tested the hypothesis that blood lipid markers are independently associated with memory performance and HC viscoelasticity-a noninvasive measure of brain tissue microstructural integrity assessed by high-resolution magnetic resonance elastography (MRE). Twenty-six individuals across the adult lifespan were recruited (14 M/12 F; mean age: 42 ± 15 y; age range: 22-78 y) and serum lipid profiles were related to episodic memory and HC viscoelasticity. All subjects were generally healthy without clinically abnormal blood lipids or memory loss. Episodic memory was negatively associated with the TG/HDL-C ratio. HC viscoelasticity was negatively associated with serum TGs and the TG/HDL-C ratio, independent of age and in the absence of associations with HC volume. These data, although cross-sectional, suggest that subtle differences in blood lipid profiles in healthy adults may contribute to a reduction in memory function and HC tissue integrity.

A high-fat diet, but not haloperidol or olanzapine administration, increases activated microglial expression in the rat brain

This study examined the effects of chronic treatment of the antipsychotic drugs, haloperidol and olanzapine, on microglial activation in the brain. In addition, we explored the interaction of these antipsychotic drugs with normal and high-fat diet. In order to measure activated microglial expression, we used [³H] PK11195 in vitro autoradiography. Male Sprague Dawley rats were given a diet of either regular chow diet or a high-fat diet, and assigned either water, haloperidol drinking solution (1.5 mg/kg), or olanzapine drinking solution (10 mg/kg) for four weeks. Following treatment, rats were euthanized and brains extracted for [³H] PK11195 autoradiography. Rats on 4 weeks of a high-fat diet showed increased [³H] PK11195 binding compared to rats on a normal diet in the temporal association cortex (19 %), ectorhinal cortex (17 %), entorhinal cortex (18 %), and perirhinal cortex (18 %), irrespective of drug treatment. These are regions associated with memory, sensory, and visual processing. Rats treated with either haloperidol or olanzapine showed no differences in [³H] PK11195 binding compared to the control group. However, there were differences between the 2 different antipsychotic medications themselves. Haloperidol increased [³H] PK11195 binding in the amygdala (23 %), ectorhinal cortex (24 %), and perihinal cortex (29 %), compared to olanzapine. These results corroborate a known role of a high-fat diet and central inflammatory changes but suggest no role of these antipsychotic drugs in promoting neuroinflammation across 4 weeks compared to normal control rats.

Effect of Allopregnanolone on Spatial Memory and Synaptic Proteins in Animal Model of Metabolic Syndrome

Metabolic Syndrome (MetS) is considered a common disorder, especially with a sedentary lifestyle and unhealthy food consumption. Cognitive impairment is one of the MetS consequences that worsens the quality of life of the patients. The study aimed to assess the therapeutic effect of the neurosteroid Allopregnalonone on spatial memory and, therefore, the expression of two synaptic plasticity markers in the hippocampus. Thirty-two male rats were divided into four groups: control groups, MetS, and MetS + Allopregnalone. Spatial memory has been evaluated by the Y-maze task and blood pressure measured by the rat tail method. Biochemical evaluation of serum glucose, insulin, lipid profile, and hippocampal expression of Synaptophysin and Associated Protein 43 (GAP-43) were performed for assessing Allopregnanolone on serum and hippocampal markers. Allopregnanolone therapy improved working spatial memory, hypertension, and biochemical markers measured in the serum and hippocampus.

Time-restricted feeding rescues high-fat-diet-induced hippocampal impairment

Feeding rodents a high-fat diet (HFD) disrupts normal behavioral rhythms, particularly meal timing. Within the brain, mistimed feeding shifts molecular rhythms in the hippocampus and impairs memory. We hypothesize that altered meal timing induced by an HFD leads to cognitive impairment and that restricting HFD access to the "active period" (i.e., night) rescues the normal hippocampal function. In male mice, ad-lib access to an HFD for 20 weeks increased body weight and fat mass, increased daytime meal consumption, reduced hippocampal long-term potentiation (LTP), and eliminated day/night differences in spatial working memory. Importantly, two weeks of time-restricted feeding (TRF) at the end of the chronic HFD protocol rescued spatial working memory and restored LTP magnitude, even though there was no change in body composition and total daily caloric intake. These findings suggest that short-term TRF is an effective mechanism for rescuing HFD-induced impaired cognition and hippocampal function.

Effects of the hydroalcoholic extract of Rosa damascena on hippocampal long-term potentiation in rats fed high-fat diet

High-fat diets (HFDs) and obesity can cause serious health problems, such as neurodegenerative diseases and cognitive impairments. Consumption of HFD is associated with reduction in hippocampal synaptic plasticity. Rosa damascena (R. damascena) is traditionally used as a dietary supplement for many disorders. This study was carried out to determine the beneficial effect of hydroalcoholic extract of R. damascena on in vivo hippocampal synaptic plasticity (long-term potentiation, LTP) in the perforant pathway (PP)-dentate gyrus (DG) pathway in rats fed with an HFD. Male Wistar rats were randomly assigned to four groups: Control, R. damascena extract (1 g/kg bw daily for 30 days), HFD (for 90 days) and HFD + extract. The population spike (PS) amplitude and slope of excitatory post-synaptic potentials (EPSP) were measured in DG area in response to stimulation applied to the PP. Serum oxidative stress biomarkers [total thiol group (TTG) and superoxide dismutase (SOD)] were measured. The results showed the HFD impaired LTP induction in the PP-DG synapses. This conclusion is supported by decreased EPSP slope and PS amplitude of LTP. R. damascena supplementation in HFD animals enhanced EPSP slope and PS amplitude of LTP in the granular cell of DG. Consumption of HFD decreased TTG and SOD. R. damascena extract consumption in the HFD animals enhanced TTG and SOD. These data indicate that R. damascena dietary supplementation can ameliorate HFD-induced alteration of synaptic plasticity, probably through its significant antioxidant effects and activate signalling pathways, which are critical in controlling synaptic plasticity.

Behavior Testing in Rodents: Highlighting Potential Confounds Affecting Variability and Reproducibility

Rodent models of brain disorders including neurodevelopmental, neuropsychiatric, and neurodegenerative diseases are essential for increasing our understanding of underlying pathology and for preclinical testing of potential treatments. Some of the most important outcome measures in such studies are behavioral. Unfortunately, reports from different labs are often conflicting, and preclinical studies in rodent models are not often corroborated in human trials. There are many well-established tests for assessing various behavioral readouts, but subtle aspects can influence measurements. Features such as housing conditions, conditions of testing, and the sex and strain of the animals can all have effects on tests of behavior. In the conduct of behavior testing, it is important to keep these features in mind to ensure the reliability and reproducibility of results. In this review, we highlight factors that we and others have encountered that can influence behavioral measures. Our goal is to increase awareness of factors that can affect behavior in rodents and to emphasize the need for detailed reporting of methods.

Systemic inflammation mediates the negative relationship between visceral adiposity and cognitive control

Elevated visceral adipose tissue (VAT) has been associated with cardiometabolic risk factors including chronic systemic low-grade inflammation. Whereas the cognitive implications of inflammation have been extensively studied in preclinical models, the influence of inflammatory cytokines on cognitive function in humans is unclear. This study aimed to investigate the relations among VAT, inflammatory cytokines, and cognitive control. We hypothesized that inflammatory markers would mediate the negative influence of VAT on selective attention. Participants between 25 and 46 years (N = 115, 43 females) underwent a DXA scan to estimate VAT. A modified Eriksen Flanker task was used to assess attentional inhibitory control while event-related potentials were recorded. ELISA was used to quantify plasma C-reactive protein (CRP) and Interleukin-6 (IL-6) concentrations. Mediation modeling while controlling for diet quality and education level revealed that CRP concentrations significantly mediated the relationship between VAT and incongruent trial accuracy (indirect effect 95% CI {-0.24, -0.01}). Further, IL-6 concentrations had a significant mediation effect on the relationship between VAT and incongruent P3 peak latency (indirect effect 95% CI {0.05, 1.39}). These results suggest that mechanisms by which visceral adiposity exerts a negative influence on cognitive function includes systemic inflammation.

Western Diet Induces Impairment of Liver-Brain Axis Accelerating Neuroinflammation and Amyloid Pathology in Alzheimer's Disease

Alzheimer's disease (AD) is an aging-dependent, irreversible neurodegenerative disorder and the most common cause of dementia. The prevailing AD hypothesis points to the central role of altered cleavage of amyloid precursor protein (APP) and formation of toxic amyloid-β (Aβ) deposits in the brain. The lack of efficient AD treatments stems from incomplete knowledge on AD causes and environmental risk factors. The role of lifestyle factors, including diet, in neurological diseases is now beginning to attract considerable attention. One of them is western diet (WD), which can lead to many serious diseases that develop with age. The aim of the study was to investigate whether WD-derived systemic disturbances may accelerate the brain neuroinflammation and amyloidogenesis at the early stages of AD development. To verify this hypothesis, transgenic mice expressing human APP with AD-causing mutations (APPswe) were fed with WD from the 3rd month of age. These mice were compared to APPswe mice, in which short-term high-grade inflammation was induced by injection of lipopolysaccharide (LPS) and to untreated APPswe mice. All experimental subgroups of animals were subsequently analyzed at 4-, 8-, and 12-months of age. APPswe mice at 4- and 8-months-old represent earlier pre-plaque stages of AD, while 12-month-old animals represent later stages of AD, with visible amyloid pathology. Already short time of WD feeding induced in 4-month-old animals such brain neuroinflammation events as enhanced astrogliosis, to a level comparable to that induced by the administration of pro-inflammatory LPS, and microglia activation in 8-month-old mice. Also, WD feeding accelerated increased Aβ production, observed already in 8-month-old animals. These brain changes corresponded to diet-induced metabolic disorders, including increased cholesterol level in 4-months of age, and advanced hypercholesterolemia and fatty liver disease in 8-month-old mice. These results indicate that the westernized pattern of nourishment is an important modifiable risk factor of AD development, and that a healthy, balanced, diet may be one of the most efficient AD prevention methods.

Hippocampal neural cell loss in high-fat diet-induced obese rats-exploring the protein networks, ultrastructure, biochemical and bioinformatical markers

OBJECTIVE

Obesity, which has become one of the main health problems, results from irregular and unhealthy nutrition. In particular, an increase in the intake of high-fat foods leads to obesity and associated disorders. It is noteworthy to specify that obese individuals have memory problems. This study aims to examine the effects of high-fat diet on hippocampus, with stereological, histopathological methods and STRING bioinformatic tool.

METHODS

Female Adult Sprague Dawley rats (n = 20) were equally divided into control (CONT) and high-fat diet (HFD) groups. The control group was given standard rat pellet feed, while the high-fat diet group was fed with a 40 % fat content for 2 months. Following the feeding program, rats were sacrificed. The collected blood samples were analyzed biochemically to determine the level of oxidative stress while performing a stereological and histopathological examination of the brain tissues. Functional protein-protein networks for BDNF, C-Fos, CAT, LPO, SOD and MPO by gene ontology (GO) enrichment analysis were evaluated.

FINDINGS

The number of neurons decreased in the HFD group compared to the CONT group. Damage to the histological structure of the hippocampus region; such as degenerate neurons, damaged mitochondria and extended cisterns of the endoplasmic reticulum was observed. Although C-Fos level and oxidative stress parameters increased in HFD group, BDNF level decreased. While BDNF and C-Fos were observed in pathways related to neuron death, oxidative stress and memory, BDNF was pronounced in the mitochondria, and C-Fos in the endoplasmic reticulum.

DISCUSSION

This study shows that changes in both BDNF and C-Fos levels in obesity due to high-fat diet increase oxidative stress and cause neuron damage in the hippocampus.

Mapping of Microglial Brain Region, Sex and Age Heterogeneity in Obesity

The prevalence of obesity has increased rapidly in recent years and has put a huge burden on healthcare worldwide. Obesity is associated with an increased risk for many comorbidities, such as cardiovascular diseases, type 2 diabetes and hypertension. The hypothalamus is a key brain region involved in the regulation of food intake and energy expenditure. Research on experimental animals has shown neuronal loss, as well as microglial activation in the hypothalamus, due to dietary-induced obesity. Microglia, the resident immune cells in the brain, are responsible for maintaining the brain homeostasis and, thus, providing an optimal environment for neuronal function. Interestingly, in obesity, microglial cells not only get activated in the hypothalamus but in other brain regions as well. Obesity is also highly associated with changes in hippocampal function, which could ultimately result in cognitive decline and dementia. Moreover, changes have also been reported in the striatum and cortex. Microglial heterogeneity is still poorly understood, not only in the context of brain region but, also, age and sex. This review will provide an overview of the currently available data on the phenotypic differences of microglial innate immunity in obesity, dependent on brain region, sex and age.

Gut microbiota: An intermediary between metabolic syndrome and cognitive deficits in schizophrenia

Gut microbiome interacts with the central nervous system tract through the gut-brain axis. Such communication involves neuronal, endocrine, and immunological mechanisms, which allows for the microbiota to affect and respond to various behaviors and psychiatric conditions. In addition, the use of atypical antipsychotic drugs (AAPDs) may interact with and even change the abundance of microbiome to potentially cause adverse effects or aggravate the disorders inherent in the disease. The regulate effects of gut microbiome has been described in several psychiatric disorders including anxiety and depression, but only a few reports have discussed the role of microbiota in AAPDs-induced Metabolic syndrome (MetS) and cognitive disorders. The following review systematically summarizes current knowledge about the gut microbiota in behavior and psychiatric illness, with the emphasis of an important role of the microbiome in the metabolism of schizophrenia and the potential for AAPDs to change the gut microbiota to promote adverse events. Prebiotics and probiotics are microbiota-management tools with documented efficacy for metabolic disturbances and cognitive deficits. Novel therapies for targeting microbiota for alleviating AAPDs-induced adverse effects are also under fast development.

HMGB1/RAGE/TLR4 axis and glutamate as novel targets for PCSK9 inhibitor in high fat cholesterol diet induced cognitive impairment and amyloidosis

AIMS

Alzheimer's disease (AD) is a leading health problem in which increased amyloid β (Aβ) accumulation may occur due to abnormal Aβ precursor protein processing by β-secretase 1 (BACE1) enzyme. Lately, neuro-inflammation was recognized as a significant contributor to its pathogenesis. Although the causes of AD are not yet well understood, much evidence has suggested that dyslipidemia has harmful effects on cognitive function and is inextricably involved in AD pathogenesis. Cholesterol is a vital molecule involved in neuronal development. Alteration in neuronal cholesterol levels affects Aβ metabolism and results in neurodegeneration. Proprotein-convertase-subtilisin/kexin type-9 (PCSK9) was found to decrease neuronal cholesterol uptake by degradation of LDL-receptor related protein 1 (LRP-1) responsible for neuronal cholesterol uptake. Accordingly, this study was designed to evaluate the effect of PCSK9-inhibition by alirocumab (Aliro) in high-fat-cholesterol-diet (HFCD)-induced-AD-like condition.

MAIN METHODS

Wistar Rats were divided into six groups; control; HFCD; HFCD and Memantine; HFCD and Aliro (4, 8 and 16 mg/kg/week) to test for ability of Aliro to modulate cognitive impairment, amyloidosis, brain cholesterol homeostasis and neuro-inflammation in HFCD-induced-AD-like condition.

KEY FINDINGS

Our results demonstrated an association between PCSK9 inhibition by Aliro and amelioration of cognitive deficit, cholesterol hemostasis and reduction of neuro-inflammation. Aliro was able to alleviate hippocampal LRP-1expression levels and reduce brain cholesterol, hippocampal BACE1, Aβ₄₂, high-mobility-group-box-1 protein, receptor for advanced-glycation-end-products and toll like receptor-4 with subsequent decrease of different inflammatory mediators as nuclear-factor-kappa-B (NF-κB), tumor-necrosis-factor-alpha (TNF-α), interleukin-1beta (IL-1β) and IL-6.

SIGNIFICANCE

PCSK9-inhibition may represent a new therapeutic target in AD especially for HFCD-induced-AD-like condition.

Agomelatine effects on fat-enriched diet induced neuroinflammation and depression-like behavior in rats

Growing evidence suggests that a high fat diet (HFD) induces oxidative stress on the central nervous system (CNS), which predisposes to mood disorders and neuroinflammation. In this study we postulated that in addition to improving mood, antidepressant therapy would reverse inflammatory changes in the brain of rats exposed to a HFD. To test our hypothesis, we measured the effect of the antidepressant agomelatine (AGO) on anxiety- and depressive-like behaviors, as well as on CNS markers of inflammation in rats rendered obese. Agomelatine is an agonist of the melatonin receptors MT1 and MT2 and an antagonist of the serotonin receptors 5HT2B and 5HT2C. A subset of rats was also treated with lipopolysaccharides (LPS) to determine how additional neuroinflammation alters behavior and affects the response to the antidepressant. Specifically, rats were subjected to a 14-week HFD, during which time behavior was evaluated twice, first at the 10th week prior to LPS and/or agomelatine, and then at the 14th week after a bi-weekly exposure to LPS (250 μg/kg) and daily treatment with agomelatine (40 mg/kg). Immediately after the second behavioral testing we measured the proinflammatory cytokines tumor necrosis factor alpha (TNF-α), interleukin 6 (IL-6) and interleukin 1 beta (IL-1β), markers of oxidative stress thiobarbituric acid reactive substances (TABRS), catalase (CAT) and glutathione peroxidase (GPx), the growth factor BDNF, as well as the apoptosis marker caspase-3. Our results show that a HFD induced an anxiety-like behavior in the open field test (OFT) at the 10th week, followed by a depressive-like behavior in the forced swim test (FST) at the 14th week. In the prefrontal and hippocampal cortices of rats exposed to a HFD we noted an overproduction of TNF-α, IL-6, IL-1β, and TABRS, together with an increase in caspase-3 activity. We also observed a decrease in BDNF, as well as reduced CAT and GPx activity in the same brain areas. Treatment with agomelatine reversed the signs of anxiety and depression, and decreased the cytokines (TNF-α, IL-6 and IL-1β), TABRS, as well as caspase-3 activity. Agomelatine also restored BDNF levels and the activity of antioxidant enzymes CAT and GPx. Our findings suggest that the anxiolytic/antidepressant effect of agomelatine in obese rats could result from a reversal of the inflammatory and oxidative stress brought about by their diet.

Oxidative stress and neuroinflammation in a rat model of co-morbid obesity and psychogenic stress

BACKGROUND

There is growing recognition for a reciprocal, bidirectional link between anxiety disorders and obesity. Although the mechanisms linking obesity and anxiety remain speculative, this bidirectionality suggests shared pathophysiological processes. Neuroinflammation and oxidative damage are implicated in both pathological anxiety and obesity. This study investigates the relative contribution of comorbid diet-induced obesity and stress-induced anxiety to neuroinflammation and oxidative stress.

METHODS

Thirty-six (36) male Lewis rats were divided into four groups based on diet type and stress exposure: 1) control diet unexposed (CDU) and 2) exposed (CDE), 3) Western-like high-saturated fat diet unexposed (WDU) and 4) exposed (WDE). Neurobehavioral tests were performed to assess anxiety-like behaviors. The catalytic concentrations of glutathione peroxidase and reductase were measured from plasma samples, and neuroinflammatory/oxidative stress biomarkers were measured from brain samples using Western blot. Correlations between behavioral phenotypes and biomarkers were assessed with Pearson's correlation procedures.

RESULTS

We found that WDE rats exhibited markedly increased levels of glial fibrillary acidic protein (185 %), catalase protein (215 %), and glutathione reductase (GSHR) enzymatic activity (418 %) relative to CDU rats. Interestingly, the brain protein levels of glutathione peroxidase (GPx) and catalase were positively associated with body weight and behavioral indices of anxiety.

CONCLUSIONS

Together, our results support a role for neuroinflammation and oxidative stress in heightened emotional reactivity to obesogenic environments and psychogenic stress. Uncovering adaptive responses to obesogenic environments characterized by high access to high-saturated fat/high-sugar diets and toxic stress has the potential to strongly impact how we treat psychiatric disorders in at-risk populations.

Pain in the Developing Brain: Early Life Factors Alter Nociception and Neurobiological Function in Adolescent Rats

Although adverse early experiences prime individuals to be at increased risk for chronic pain, little research has examined the trauma–pain relationship in early life or the underlying mechanisms that drive pathology over time. Given that early experiences can potentiate the nociceptive response, this study aimed to examine the effects of a high-fat, high-sugar (HFHS) diet and early life stress (maternal separation [MS]) on pain outcomes in male and female adolescent rats. Half of the rats also underwent a plantar-incision surgery to investigate how the pain system responded to a mildly painful stimuli in adolescence. Compared with controls, animals that were on the HFHS diet, experienced MS, or had exposure to both, exhibited increased anxiety-like behavior and altered thermal and mechanical nociception at baseline and following the surgery. Advanced magnetic resonance imaging demonstrated that the HFHS diet and MS altered the maturation of the brain, leading to changes in brain volume and diffusivity within the anterior cingulate, amygdala, corpus callosum, nucleus accumbens, and thalamus, while also modifying the integrity of the corticospinal tracts. The effects of MS and HFHS diet were often cumulative, producing exacerbated pain sensitivity and increased neurobiological change. As early experiences are modifiable, understanding their role in pain may provide targets for early intervention/prevention.

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.

Working memory and hippocampal expression of BDNF, ARC, and P-STAT3 in rats: effects of diet and exercise

OBJECTIVES

Mounting evidence suggests diet and exercise influence learning and memory (LM). We compared a high-fat, high-sucrose Western diet (WD) to a plant-based, amylose/amylopectin blend, lower-fat diet known as the Daniel Fast (DF) in rats with and without regular aerobic exercise on a task of spatial working memory (WM).

METHODS

Rats were randomly assigned to the WD or DF at 6 weeks of age. Exercised rats (WD-E, DF-E) ran on a treadmill 3 times/week for 30 min while the sedentary rats did not (WD-S, DF-S). Rats adhered to these assignments for 12 weeks, inclusive of ab libitum food intake, after which mild food restriction was implemented to encourage responding during WM testing. For nine months, WM performance was assessed once daily, six days per week, after which hippocampal sections were collected for subsequent analysis of brain-derived neurotrophic factor (BDNF), activity-regulated cytoskeletal protein (ARC), and signal transducer and activator of transcription 3 (P-STAT3, Tyr705).

RESULTS

DF-E rats exhibited the best DSA performance. Surprisingly, the WD-S group outperformed the WD-E group, but had significantly lower BDNF and ARC relative to the DF-S group, with a similar trend from the WD-E group. P-STAT3 expression was also significantly elevated in the WD-S group compared to both the DF-S and WD-E groups.

DISCUSSION

These results support previous research demonstrating negative effects of the WD on spatial LM, demonstrate the plant-based DF regimen combined with chronic aerobic exercise produces measurable WM and neuroprotective benefits, and suggest the need to carefully design exercise prescriptions to avoid over-stressing individuals making concurrent dietary changes.

Saroglitazar, a novel dual PPAR-α/γ agonist, reverses high fat-low protein diet-induced metabolic and cognitive aberrations in C57BL/6J male mice

AIMS

Insulin resistance (IR) has become one of the major causative factors for the pathogenesis of various metabolic and neurometabolic diseases. The sedentary lifestyle in association with the consumption of protein-deficient and high-calorie diet results in IR development. This study was aimed to evaluate the neuroprotective effects of Saroglitazar (SGZ), a dual peroxisome-proliferator activated receptor (PPAR-α/γ) in a high fat-low protein diet (HFLPD) fed mouse model of MetS and associated cognitive deficits.

METHODS

Adult male C57BL/6J mice were fed with HFLPD plus 15% oral fructose solution for 16 weeks. Starting at the 13th week, SGZ (5 & 10 mg/kg; p.o.) was administered along with HFLPD for four weeks, i.e., the 12th to 16th week of the study groups. Various physiological, serum metabolic, neurobehavioral, neuroinflammatory, and oxidative stress parameters were assessed. The brain histopathology and mRNA expression of diverse genes in specific brain regions were also estimated.

RESULTS

The treatment with SGZ at both doses have significantly reversed various HFLPD-induced metabolic and cognitive alterations by improving the glucose and lipid profile in the periphery in addition to the enhanced cerebral glucose homeostasis, BBB integrity, reduced oxidative stress, and neuroinflammation. Furthermore, the SGZ improved locomotion and memory retention while reducing the HFLPD-induced anxiety-like behaviors in the mice.

CONCLUSIONS

SGZ treatment showed significant metabo-neuroprotective effects in mice fed with HFLPD, possibly through peripherally mediated activation of PPAR-α/γ and insulin downstream signaling in the cortex and hippocampus.

Ginger and turmeric lipid-solubles attenuate heated oil-induced oxidative stress in the brain via the upregulation of NRF2 and improve cognitive function in rats

In this study, we elucidated the modulatory potentials of lipid-solubles from ginger and turmeric that may migrate to oils during heating on the brain antioxidant defense and cognitive response in rats. Male Wistar rats were fed with control diet [including native canola oil (N-CNO), and native sunflower oil (N-SFO)], or experimental diets [including heated canola oil (H-CNO), heated sunflower oil (H-SFO), heated canola oil with ginger (H-CNO + GI), heated canola oil with turmeric (H-CNO + TU), heated sunflower oil with ginger (H-SFO + GI), heated sunflower oil with turmeric (H-SFO + TU)] for 90 days. Memory parameters [Morris water maze, elevated plus maze, novel object recognition test, T-maze (spontaneous alteration)], locomotor skills (open field test and rotarod test), antioxidant defense enzymes, reactive oxygen species, NOS2, ICAM-1, and NRF-2 level in the brain were assessed. Compared to their respective controls, heated oil-fed rats, but not those fed oils heated with ginger or turmeric, showed significant (p < 0.05) reduction in the memory, motor coordination skills, antioxidant defense enzymes, and NRF-2 activation in the brain. Compared to their respective controls, the brain NOS-2 and ICAM-1 were significantly (p < 0.05) increased in heated oil-fed rats, but not those fed oils heated with ginger or turmeric. Chronic intake of repeatedly heated oil causes brain dysfunction by inducing oxidative stress through NRF-2 downregulation. Lipid-solubles from ginger and turmeric that may migrate to oil during heating prevent the oxidative stress and cognitive dysfunction triggered by heated oils in rats.

Thymoquinone Protects Neurons in the Cerebellum of Rats through Mitigating Oxidative Stress and Inflammation Following High-Fat Diet Supplementation

High-fat diet (HFD) is a major problem causing neuronal damage. Thymoquinone (TQ) could regulate oxidative stress and the inflammatory process. Hence, the present study elucidated the significant role of TQ on oxidative stress, inflammation, as well as morphological changes in the cerebellum of rats with HFD. Rats were divided into three groups as (1) control, (2) saturated HFD for eight weeks and (3) HFD supplementation (four weeks) followed by TQ 300 mg/kg/day treated (four weeks). After treatment, blood samples were collected to measure oxidative stress markers glutathione (GSH), malondialdehyde (MDA), superoxide dismutase (SOD), and inflammatory cytokines. Furthermore, neuronal morphological changes were also observed in the cerebellum of the rats. HFD rats show higher body weight (286.5 ± 7.4 g) as compared with the control group (224.67 ± 1.78 g). TQ treatment significantly (p < 0.05) lowered the body weight (225.83 ± 13.15 g). TQ produced a significant (p < 0.05) reduction in cholesterol, triglycerides, high-density lipoprotein (HDL), and low-density lipoprotein (LDL). The antioxidative enzymes significantly reduced in HFD rats (GSH, 1.46 ± 0.36 mol/L and SOD, 99.13 ± 5.41 µmol/mL) as compared with the control group (GSH, 6.25 ± 0.36 mol/L and SOD, 159.67 ± 10.67 µmol/mL). MDA was increased significantly in HFD rats (2.05 ± 0.25 nmol/L) compared to the control group (0.695 ± 0.11 nmol/L). Surprisingly, treatment with TQ could improve the level of GSH, MDA, and SOD. TQ treatment significantly (p < 0.05) reduced the inflammatory markers as compared with HFD alone. TQ treatment minimizes neuronal damage as well as reduces inflammation and improves antioxidant enzymes. TQ can be considered as a promising agent in preventing the neuronal morphological changes in the cerebellum of obese populations.

Challenges in researching the immune pathways between early life adversity and psychopathology

Exposure to childhood adversity is a critical risk factor for the development of psychopathology. A growing field of research examines how exposure to childhood adversity is translated into biological risk for psychopathology through alterations in immune system functioning, most notably heightened levels of inflammation biomarkers. Though our knowledge about how childhood adversity can instantiate biological risk for psychopathology is growing, there remain many challenges and gaps in the field to understand how inflammation from childhood adversity contributes to psychopathology. This paper reviews research on the inflammatory outcomes arising from childhood adversity and presents four major challenges that future research must address: (a) the measurement of childhood adversity, (b) the measurement of inflammation, (c) the identification of mediators between childhood adversity and inflammation, and (d) the identification of moderators of inflammatory outcomes following childhood adversity. We discuss synergies and inconsistencies in the literature to summarize the current understanding of the association between childhood adversity, a proinflammatory phenotype, and the biological risk for psychopathology. We discuss the clinical implications of the inflammatory links between childhood adversity and psychopathology, including possibilities for intervention. Finally, this review conclude by delineates future directions for research, including issues of how best to detect, prevent, and understand these “hidden wounds” of childhood adversity.

Interaction Mechanisms Between Major Depressive Disorder and Non-alcoholic Fatty Liver Disease

Major depressive disorder (MDD), which is highly associated with non-alcoholic fatty liver disease (NAFLD), has complex pathogenic mechanisms. However, a limited number of studies have evaluated the mutual pathomechanisms involved in MDD and NAFLD development. Chronic stress-mediated elevations in glucocorticoid (GC) levels play an important role in the development of MDD-related NAFLD. Elevated GC levels can induce the release of inflammatory factors and changes in gut permeability. Elevated levels of inflammatory factors activate the hypothalamic-pituitary-adrenal (HPA) axis, which further increases the release of GC. At the same time, changes in gut permeability promote the release of inflammatory factors, which results in a vicious circle among the three, causing disease outbreaks. Even though the specific role of the thyroid hormone (TH) in this pathogenesis has not been fully established, it is highly correlated with MDD and NAFLD. Therefore, changing lifestyles and reducing psychological stress levels are necessary measures for preventing MDD-related NAFLD. Among them, GC inhibitors and receptor antagonists may be key in the alleviation of early and mid-term disease progression. However, combination medications may be important in late-stage diseases, but they are associated with various side effects. Traditional Chinese medicines have been shown to be potential therapeutic alternatives for such complex diseases.

Hippocampal Glycerol-3-Phosphate Acyltransferases 4 and BDNF in the Progress of Obesity-Induced Depression

BACKGROUND

Obesity has been reported to lead to increased incidence of depression. Glycerol-3-phosphate acyltransferases 4 (GPAT4) is involved in triacylglycerol synthesis and plays an important role in the occurrence of obesity. GPAT4 is the only one of GPAT family expressed in the brain. The aim of this study is to investigate if central GPAT4 is associated with obesity-related depression and its underlying mechanism.

RESULTS

A high-fat diet resulted in increased body weight and blood lipid. HFD induced depression like behavior in the force swimming test, tail suspension test and sucrose preference test. HFD significantly up-regulated the expression of GPAT4 in hippocampus, IL-1β, IL-6, TNF-α and NF-κB, accompanied with down-regulation of BDNF expression in hippocampus and ventromedical hypothalamus, which was attributed to AMP-activated protein kinase (AMPK) and cAMP-response element binding protein (CREB).

CONCLUSION

Our findings suggest that hippocampal GPAT4 may participate in HFD induced depression through AMPK/CREB/BDNF pathway, which provides insights into a clinical target for obesity-associated depression intervention.

Zerumbone augments cognitive enhancement potentials of EPA+DHA: insight from a hyperlipidaemic rat model

Hyperlipidaemia and cognitive dysfunction (CD) are the two public health concerns. Though hyperlipidaemia has been comprehensively studied in respect to CVD, its role on CD needs to be explored. Hence, we evaluated hyperlipidaemia as a risk factor for CD and the efficacy of EPA (20 : 5n-3) + DHA (22 : 6n-3) and zerumbone (Z) in modulating CD under hyperlipidaemic conditions. Male Wistar rats (Rattus norvegicus) were fed control, high-fat (HF), high-fat + fish oil (HF + F), high-fat + zerumbone (HF+Z) and high-fat + fish oil + zerumbone (HF+F+Z) containing diets. After a 30 d feeding trial, memory parameters (Morris water maze, elevated plus maze (transfer latency) and T-maze (spontaneous alteration)) and locomotor skills (open field test and rotarod test) were assessed. Hyperlipidaemia significantly (P < 0·05) reduced memory and motor coordination skills compared with control. However, the administration of EPA + DHA and zerumbone significantly (P < 0·05) restored the hyperlipidaemia-induced loss of memory and motor coordination skills. Collectively, our data imply that hyperlipidaemia causes CD by decreasing memory and motor coordination skills, and administration of EPA + DHA and zerumbone prevents hyperlipidaemia-induced CD. The augmented effect of EPA + DHA, together with zerumbone, discloses a promising strategy for lowering the severity of CD in hyperlipidaemic conditions.

Sweet but Bitter: Focus on Fructose Impact on Brain Function in Rodent Models

Fructose consumption has drastically increased during the last decades due to the extensive commercial use of high-fructose corn syrup as a sweetener for beverages, snacks and baked goods. Fructose overconsumption is known to induce obesity, dyslipidemia, insulin resistance and inflammation, and its metabolism is considered partially responsible for its role in several metabolic diseases. Indeed, the primary metabolites and by-products of gut and hepatic fructolysis may impair the functions of extrahepatic tissues and organs. However, fructose itself causes an adenosine triphosphate (ATP) depletion that triggers inflammation and oxidative stress. Many studies have dealt with the effects of this sugar on various organs, while the impact of fructose on brain function is, to date, less explored, despite the relevance of this issue. Notably, fructose transporters and fructose metabolizing enzymes are present in brain cells. In addition, it has emerged that fructose consumption, even in the short term, can adversely influence brain health by promoting neuroinflammation, brain mitochondrial dysfunction and oxidative stress, as well as insulin resistance. Fructose influence on synaptic plasticity and cognition, with a major impact on critical regions for learning and memory, was also reported. In this review, we discuss emerging data about fructose effects on brain health in rodent models, with special reference to the regulation of food intake, inflammation, mitochondrial function and oxidative stress, insulin signaling and cognitive function.

Experimental Pulmonary Tuberculosis in the Absence of Detectable Brain Infection Induces Neuroinflammation and Behavioural Abnormalities in Male BALB/c Mice

Tuberculosis (TB) is a chronic infectious disease in which prolonged, non-resolutive inflammation of the lung may lead to metabolic and neuroendocrine dysfunction. Previous studies have reported that individuals coursing pulmonary TB experience cognitive or behavioural changes; however, the pathogenic substrate of such manifestations have remained unknown. Here, using a mouse model of progressive pulmonary TB, we report that, even in the absence of brain infection, TB is associated with marked increased synthesis of both inflammatory and anti-inflammatory cytokines in discrete brain areas such as the hypothalamus, the hippocampal formation and cerebellum accompanied by substantial changes in the synthesis of neurotransmitters. Moreover, histopathological findings of neurodegeneration and neuronal death were found as infection progressed with activation of p38, JNK and reduction in the BDNF levels. Finally, we perform behavioural analysis in infected mice throughout the infection, and our data show that the cytokine and neurochemical changes were associated with a marked onset of cognitive impairment as well as depressive- and anxiety-like behaviour. Altogether, our results suggest that besides pulmonary damage, TB is accompanied by an extensive neuroinflammatory and neurodegenerative state which explains some of the behavioural abnormalities found in TB patients.

The cafeteria diet: A standardized protocol and its effects on behavior

Obesity is a major health risk, with junk food consumption playing a central role in weight gain, because of its high palatability and high-energy nutrients. The Cafeteria (CAF) diet model for animal experiments consists of the same tasty but unhealthy food products that people eat (e.g. hot dogs and muffins), and considers variety, novelty and secondary food features, such as smell and texture. This model, therefore, mimics human eating patterns better than other models. In this paper, we systematically review studies that have used a CAF diet in behavioral experiments and propose a standardized CAF diet protocol. The proposed diet is ad libitum and voluntary; combines different textures, nutrients and tastes, including salty and sweet products; and it is rotated and varied. Our summary of the behavioral effects of CAF diet show that it alters meal patterns, reduces the hedonic value of other rewards, and tends to reduce stress and spatial memory. So far, no clear effects of CAF diet were found on locomotor activity, impulsivity, coping and social behavior.

Dietary patterns in relation to gestational depression and sleep disturbance in Chinese pregnant women

AIM

To investigate the association of dietary patterns with gestational depression and sleep disturbance.

METHODS

Women in early pregnancy were recruited from the Chinese Pregnant Women Cohort Study (CPWCS) through July 25th, 2017 to November 26th, 2018, and eventually 7615 participants were included in this study. The qualitative food frequency questionnaire (Q-FFQ), Edinburgh Postnatal Depression Scale (EPDS), and the Pittsburgh Sleep Quality Index (PSQI) were used to assess dietary, depression and sleep quality during pregnancy, respectively. Dietary patterns were derived by factor analysis. Logistic regression was used to estimate the odds ratio (OR) and 95% confidence interval (95% CI) of each outcome according to quartiles of each dietary pattern.

RESULTS

Five dietary patterns were identified. Participants with the highest quartile in plant-based pattern had a significantly lower likelihood of mental problems (OR: 95% CI for depression: 0.66, 0.55-0.79; sleep disturbance: 0.80, 0.68-0.93); Similar results were observed in vitamin-rich pattern (OR: 95% CI for depression: 0.46, 0.38-0.55; sleep disturbance: 0.76, 0.65-0.89); However, contrary results were found in high-fat pattern (OR: 95% CI for depression: 2.15, 1.25-1.85; sleep disturbance: 1.43, 1.22-1.67); In animal protein-rich pattern, participants with the highest quartile had a decreased likelihood of depression (OR: 0.80, 95% CI: 0.67-0.96). As for bean products pattern, participants with the highest quartile had an increased risk of depression (OR: 1.28, 95% CI:1.06-1.53). Interactions of dietary patterns and lifestyles on mental disorders were observed.

CONCLUSION

Dietary patterns were associated with gestational depression and sleep disturbance. Relevant departments and maternal and child health personnel should conduct health education for pregnant women and guide them to eat properly.

High-Fat and High-Sucrose Diets Impair Time-of-Day Differences in Spatial Working Memory of Male Mice

OBJECTIVE

This study aimed to investigate both the long-term and short-term impacts of high-fat diets (HFD) or high-sucrose diets (HSD) on the normal diurnal pattern of cognitive function, protein expression, and the molecular clock in mice.

METHODS

This study used both 6-month and 4-week feeding strategies by providing male C57BL/6J mice access to either a standard chow, HFD, or HSD. Spatial working memory and synaptic plasticity were assessed both day and night, and hippocampal tissue was measured for changes in NMDA and AMPA receptor subunits (GluN2B, GluA1), as well as molecular clock gene expression.

RESULTS

HFD and HSD both disrupted normal day/night fluctuations in spatial working memory and synaptic plasticity. Mice fed HFD altered their food intake to consume more calories during the day. Both diets disrupted normal hippocampal clock gene expression, and HFD reduced GluN2B levels in hippocampal tissue.

CONCLUSIONS

Taken together, these results suggest that both HFD and HSD induce a loss of day/night performance in spatial working memory and synaptic plasticity as well as trigger a cascade of changes that include disruption to the hippocampal molecular clock.

Western Diet: Implications for Brain Function and Behavior

The Western diet (WD) pattern characterized by high daily intake of saturated fats and refined carbohydrates often leads to obesity and overweight, and it has been linked to cognitive impairment and emotional disorders in both animal models and humans. This dietary pattern alters the composition of gut microbiota, influencing brain function by different mechanisms involving the gut-brain axis. In addition, long-term exposure to highly palatable foods typical of WD could induce addictive-like eating behaviors and hypothalamic-pituitary-adrenal (HPA) axis dysregulation associated with chronic stress, anxiety, and depression. In turn, chronic stress modulates eating behavior, and it could have detrimental effects on different brain regions such as the hippocampus, hypothalamus, amygdala, and several cortical regions. Moreover, obesity and overweight induce neuroinflammation, causing neuronal dysfunction. In this review, we summarize the current scientific evidence about the mechanisms and factors relating WD consumption with altered brain function and behavior. Possible therapeutic interventions and limitations are also discussed, aiming to tackle and prevent this current pandemic.

Immunometabolic Changes in Glia - A Potential Role in the Pathophysiology of Obesity and Diabetes

Chronic low-grade inflammation is a feature of the pathophysiology of obesity and diabetes in the CNS as well as peripheral tissues. Glial cells are critical mediators of the response to inflammation in the brain. Key features of glia include their metabolic flexibility, sensitivity to changes in the CNS microenvironment, and ability to rapidly adapt their function accordingly. They are specialised cells which cooperate to promote and preserve neuronal health, playing important roles in regulating the activity of neuronal networks across the brain during different life stages. Increasing evidence points to a role of glia, most notably astrocytes and microglia, in the systemic regulation of energy and glucose homeostasis in the course of normal physiological control and during disease. Inflammation is an energetically expensive process that requires adaptive changes in cellular metabolism and, in turn, metabolic intermediates can also have immunomodulatory actions. Such "immunometabolic" changes in peripheral immune cells have been implicated in contributing to disease pathology in obesity and diabetes. This review will discuss the evidence for a role of immunometabolic changes in glial cells in the systemic regulation of energy and glucose homeostasis, and how this changes in the context of obesity and diabetes.

Copper Ionophores as Novel Antiobesity Therapeutics

The therapeutic utility of the copper ionophore disulfiram was investigated in a diet-induced obesity mouse model (C57BL/6J background), both through administration in feed (0.05 to 1% (w/w)) and via oral gavage (150 mg/kg) for up to eight weeks. Mice were monitored for body weight, fat deposition (perigonadal fat pads), metabolic changes (e.g., glucose dyshomeostasis) and pathologies (e.g., hepatic steatosis, hyperglycaemia and hypertriglyceridemia) associated with a high-fat diet. Metal-related pharmacological effects across major organs and serums were investigated using inductively coupled plasma mass spectrometry (ICP-MS). Disulfiram treatments (all modes) augmented hepatic copper in mice, markedly moderated body weight and abolished the deleterious systemic changes associated with a high-fat diet. Likewise, another chemically distinct copper ionophore H2(gtsm), administered daily (oral gavage), also augmented hepatic copper and moderated mouse body weight. Postmortem histological examinations of the liver and other major organs, together with serum aminotransferases, supported the reported therapeutic safety of disulfiram. Disulfiram specifically altered systemic copper in mice and altered hepatic copper metabolism, perturbing the incorporation of copper into ceruloplasmin (holo-ceruloplasmin biosynthesis) and subsequently reducing serum copper concentrations. Serum ceruloplasmin represents a biomarker for disulfiram activity. Our results establish copper ionophores as a potential class of antiobesity agents.

High fat diet-induced obesity causes a reduction in brain tyrosine hydroxylase levels and non-motor features in rats through metabolic dysfunction, neuroinflammation and oxidative stress

Obesity is a health problem that has been associated with neuroinflammation, decreased cognitive functions and development of neurodegenerative diseases. Parkinson's disease (PD) is a chronic neurodegenerative condition characterized by motor and non-motor abnormalities, increased brain inflammation, α-synuclein protein aggregation and dopaminergic neuron loss that is associated with decreased levels of tyrosine hydroxylase (TH) in the brain. Diet-induced obesity is a global epidemic and its role as a risk factor for PD is not clear. Herein, we showed that 25 weeks on a high-fat diet (HFD) promotes significant alterations in the nigrostriatal axis of Wistar rats. Obesity induced by HFD exposure caused a reduction in TH levels and increased TH phosphorylation at serine 40 in the ventral tegmental area. These effects were associated with insulin resistance, increased tumor necrosis factor-α levels, oxidative stress, astrogliosis and microglia activation. No difference was detected in the levels of α-synuclein. Obesity also induced impairment of locomotor activity, total mobility and anxiety-related behaviors that were identified in the open-field and light/dark tasks. There were no changes in motor coordination or memory. Together, these data suggest that the reduction of TH levels in the nigrostriatal axis occurs through an α-synuclein-independent pathway and can be attributed to brain inflammation, oxidative/nitrosative stress and metabolic disorders induced by obesity.

Ameliorative effects of apple cider vinegar on neurological complications via regulation of oxidative stress markers

Dementia linked with cognitive impairments is the most prominent indication of Alzheimer's disease (AD). In the current investigation, we have examined the streptozotocin- (STZ) induced cellular toxicity in mouse neuroblastoma (N2A) cells, and Zn with the high-fat diet- (HFD) induced neurotoxicity in mouse brain. These cells and animals were pretreated with apple cider vinegar (ACV), Chrysin, and Rivastigmine to examine their protection against cellular toxicity and neurotoxicity. Experiments have affirmed that pretreatment of ACV, Chrysin, and Rivastigmine has displayed protective outcomes in MTT reduction, tau phosphorylation, amyloid aggregation, attenuated memory impairment as well as oxidative stress, and protected cholinergic hippocampal neurons from degeneration. ACV showed better antioxidant and neuroprotection potential as compared with Chrysin and Rivastigmine. So the existence of excitatory/inhibitory enzymatic activity and higher antioxidant potential indicate that ACV, as a food beverage in a regular diet, could be promising and effective against neurological complications such as AD. PRACTICAL APPLICATIONS: In the Urban lifestyle, HFD and stress are the critical factors of various chronic and prevalent diseases, including diabetes, obesity, cardiovascular, and neurodegenerative disorders like AD. We are already familiar with the multiple benefits of ACV, such as weight loss, antimicrobial activity, diabetes, skin disorders. So in the current research work, we have gauged the effectiveness of ACV against neurological complications in comparison with a synthetic flavonoid (Chrysin) and an anti-Alzheimer's drug (Rivastigmine). To enhance the pragmatic orientation of our results, we have used the ACV in our study, which is readily available in the market for domestic consumption. All the cellular, biochemical, behavioral, and histopathological data revealed that ACV had high antioxidant potential. Our findings suggest that the addition of ACV as a food additive in the daily diet may reduce the threat of multiple neurodegenerative diseases. Therefore, our study could be the precursor of a new pharmacological therapeutic approach via ACV toward cognitive impairments associated with Alzheimer's disease.

Marine n-3 polyunsaturated fatty acids: Efficacy on inflammatory-based disorders

Inflammation is a physiological response to injury, stimulating tissue repair and regeneration. However, the presence of peculiar individual conditions can negatively perturb the resolution phase eventually leading to a state of low-grade systemic chronic inflammation, characterized by tissue and organ damages and increased susceptibility to non-communicable disease. Marine n-3 polyunsaturated fatty acids (n-3 PUFAs), mainly eicosapentaenoic (EPA) and docosahexaenoic acid (DHA), are able to influence many aspects of this process. Experiments performed in various animal models of obesity, Alzheimer's disease and multiple sclerosis have demonstrated that n-3 PUFAs can modulate the basic mechanisms as well as the disease progression. This review describes the available data from experimental studies to the clinical trials.

Effect of Vigna angularis on High-Fat Diet-Induced Memory and Cognitive Impairments

High-fat diet (HFD)-induced obesity is related to cognitive and memory dysfunction. Much attention was focused on functional foods as a therapeutic strategy to treat cognitive decline by obesity. In the present study, we confirmed the protective effect of Vigna angularis (VA) on cognitive and memory impairment in an obese mouse model. For 16 weeks, mice were fed HFD and VA extract was administered during 4 weeks at 100 and 200 mg/kg. The cognitive abilities of HFD-induced mice were evaluated using behavioral tests. Compared with the control group, VA groups were improved spatial and recognition ability. In T-maze and novel object recognition tests, VA 100 and VA 200 groups showed increased ratios of exploration of a novel object/route compared to a familiar object/route. Moreover, VA 100 and VA 200 groups reached the platform faster than the control group in a Morris water maze test. Therefore, VA extract may protect against HFD-induced cognitive impairment and memory dysfunction. (PNU-IACUC; approval no. PNU-2019-2166).

Sex-specific effects of high-fat diet on cognitive impairment in a mouse model of VCID

Mid-life metabolic disease (ie, obesity, diabetes, and prediabetes) causes vascular dysfunction and is a risk factor for vascular contributions to cognitive impairment and dementia (VCID), particularly in women. Using middle-aged mice, we modeled metabolic disease (obesity/prediabetes) via chronic high-fat (HF) diet and modeled VCID via unilateral common carotid artery occlusion. VCID impaired spatial memory in both sexes, but episodic-like memory in females only. HF diet caused greater weight gain and glucose intolerance in middle-aged females than males. HF diet alone impaired episodic-like memory in both sexes, but spatial memory in females only. Finally, the combination of HF diet and VCID elicited cognitive impairments in all tests, in both sexes. Sex-specific correlations were found between metabolic outcomes and memory. Notably, both visceral fat and the pro-inflammatory cytokine tumor necrosis factor alpha correlated with spatial memory deficits in middle-aged females, but not males. Overall, our data show that HF diet causes greater metabolic impairment and a wider array of cognitive deficits in middle-aged females than males. The combination of HF diet with VCID elicits deficits across multiple cognitive domains in both sexes. Our data are in line with clinical data, which shows that mid-life metabolic disease increases VCID risk, particularly in females.

Brain and muscle adaptation to high-fat diets and exercise: Metabolic transporters, enzymes and substrates in the rat cortex and muscle

There is evidence suggesting that the effects of diet and physical activity on physical and mental well-being are the result of altered metabolic profiles. Though the central and peripheral systems work in tandem, the interactions between peripheral and central changes that lead to these altered states of well-being remains elusive. We measured changes in the metabolic profile of brain (cortex) and muscle (soleus and plantaris) tissue in rats following 5-weeks of treadmill exercise and/or a high-fat diet to evaluate peripheral and central interactions as well as identify any common adaptive mechanisms. To characterize changes in metabolic profiles, we measured relative changes in key metabolic enzymes (COX IV, hexokinase, LDHB, PFK), substrates (BHB, FFA, glucose, lactate, insulin, glycogen, BDNF) and transporters (MCT1, MCT2, MCT4, GLUT1, GLUT3). In the cortex, there was an increase in MCT1 and a decrease in glycogen following the high-fat diet, suggesting an increased reliance on monocarboxylates. Muscle changes were dependent muscle type. Within the plantaris, a high-fat diet increased the oxidative capacity of the muscle likely supported by increased glycolysis, whereas exercise increased the oxidative capacity of the muscle likely supported via increased glycogen synthesis. There was no effect of diet on soleus measurements, but exercise increased its oxidative capacity likely fueled by endogenous and exogenous monocarboxylates. For both the plantaris and soleus, combining exercise training and high-fat diet mediated results, resulting in a middling effect. Together, these results indicate the variable adaptions of two main metabolic pathways: glycolysis and oxidative phosphorylation. The results also suggest a dynamic relationship between the brain and body.

Chronic NaHS treatment improves spatial and passive avoidance learning and memory and anxiety-like behavior and decreases oxidative stress in rats fed with a high-fat diet

Cognitive function is impaired by increased consumption of a high-fat diet (HFD). Also, HFD consumption can alter hydrogen sulfide (H₂S) metabolism. H₂S is an important signaling molecule with antioxidant effects that regulates multiple functions in the brain. In the present study, we investigated the effect of sodium hydrosulfide (NaHS, an H₂S donor) on cognitive impairment and oxidative stress changes induced by HFD consumption. Following 11 weeks of HFD regimes in Wistar rats, elevated plus-maze (EPM), Morris water maze (MWM), and passive avoidance learning (PAL) tasks were used to evaluate the anxiety-like behavior and spatial and passive learning and memory, respectively. Daily intraperitoneal injection of NaHS was done during the dietary regimen. Serum and hippocampal oxidative stress biomarkers (malondialdehyde (MDA), total antioxidant capacity (TAC), and total oxidant status (TOS)) were measured. We demonstrated that treatment with NaHS ameliorated the impairment in the retrieval of reference memory and passive avoidance learning. Moreover, HFD increased anxiety-like behavior, which was reversed by the administration of NaHS. Additionally, the increase in MDA and TOS and the decrease in TAC induced by HFD in the serum and hippocampus were significantly reduced following administration of NaHS. These results indicate that NaHS could significantly ameliorate HFD-induced spatial and passive learning and memory impairment and anxiety-like behavior, at least in part, via its antioxidant activities. Therefore, the administration of NaHS can provide a therapeutic approach for HFD-induced memory impairment.

Gut Hormone GIP Induces Inflammation and Insulin Resistance in the Hypothalamus

The hypothalamus plays a critical role in controlling energy balance. High-fat diet (HFD) feeding increases the gene expression of proinflammatory mediators and decreases insulin actions in the hypothalamus. Here, we show that a gut-derived hormone, glucose-dependent insulinotropic polypeptide (GIP), whose levels are elevated during diet-induced obesity, promotes and mediates hypothalamic inflammation and insulin resistance during HFD-induced obesity. Unbiased ribonucleic acid sequencing of GIP-stimulated hypothalami revealed that hypothalamic pathways most affected by intracerebroventricular (ICV) GIP stimulation were related to inflammatory-related responses. Subsequent analysis demonstrated that GIP administered either peripherally or centrally, increased proinflammatory-related factors such as Il-6 and Socs3 in the hypothalamus, but not in the cortex of C57BL/6J male mice. Consistently, hypothalamic activation of IκB kinase-β inflammatory signaling was induced by ICV GIP. Further, hypothalamic levels of proinflammatory cytokines and Socs3 were significantly reduced by an antagonistic GIP receptor (GIPR) antibody and by GIPR deficiency. Additionally, centrally administered GIP reduced anorectic actions of insulin in the brain and diminished insulin-induced phosphorylation of Protein kinase B and Glycogen synthase kinase 3β in the hypothalamus. Collectively, these findings reveal a previously unrecognized role for brain GIP signaling in diet-induced inflammation and insulin resistance in the hypothalamus.

The Biomedical Uses of Inositols: A Nutraceutical Approach to Metabolic Dysfunction in Aging and Neurodegenerative Diseases

Inositols are sugar-like compounds that are widely distributed in nature and are a part of membrane molecules, participating as second messengers in several cell-signaling processes. Isolation and characterization of inositol phosphoglycans containing myo- or d-chiro-inositol have been milestones for understanding the physiological regulation of insulin signaling. Other functions of inositols have been derived from the existence of multiple stereoisomers, which may confer antioxidant properties. In the brain, fluctuation of inositols in extracellular and intracellular compartments regulates neuronal and glial activity. Myo-inositol imbalance is observed in psychiatric diseases and its use shows efficacy for treatment of depression, anxiety, and compulsive disorders. Epi- and scyllo-inositol isomers are capable of stabilizing non-toxic forms of β-amyloid proteins, which are characteristic of Alzheimer's disease and cognitive dementia in Down's syndrome, both associated with brain insulin resistance. However, uncertainties of the intrinsic mechanisms of inositols regarding their biology are still unsolved. This work presents a critical review of inositol actions on insulin signaling, oxidative stress, and endothelial dysfunction, and its potential for either preventing or delaying cognitive impairment in aging and neurodegenerative diseases. The biomedical uses of inositols may represent a paradigm in the industrial approach perspective, which has generated growing interest for two decades, accompanied by clinical trials for Alzheimer's disease.

Omega-3 fatty acids ameliorate cognitive dysfunction in schizophrenia patients with metabolic syndrome

Our previous study showed that metabolic abnormalities reduced the levels of brain-derived neurotrophic factor (BDNF) and deteriorated cognitive performance in patients with schizophrenia. Inflammation may play a key role in this process. Omega-3 fatty acids have been documented to ameliorate inflammation. Therefore, we hypothesized that omega-3 fatty acids may be of value in enhancing BDNF levels and improving cognitive function in patients with schizophrenia with metabolic syndrome (MetS). We recruited 80 patients with both schizophrenia and MetS who received long-term olanzapine monotherapy. The enzyme-linked immunosorbent assay was used to measure the plasma levels of C-reactive protein (CRP), interleukin-6 (IL-6) and tumor necrosis factor-alpha (TNF-α). The patients were randomly assigned to the OMG-3 group (n = 40) or the placebo group (n = 40). Of the 80 patients who consented to the study, 72 completed this 12-week RCT. The primary outcome was the changes from baseline to 12 weeks in clinical characteristics and the levels of BDNF, CRP, IL-6 and TNF-α. There was a significant correlation between omega-3 fatty acid treatment and enhanced delayed memory factor in the RBANS assessment (F_group×time = 6.82; df = 1, 66; P = 0.01) when the patients completed this study. Along with cognitive improvement, omega-3 fatty acids enhanced BDNF (F_group×time = 4.93; df = 1, 66; P = 0.03) and reduced CRP (F_group×time = 17.11; df = 1, 66; P < 0.01), IL-6 (F_group×time = 9.71; df = 1, 66; P < 0.004) and TNF-α (F_group×time = 6.71; df = 1, 66; P = 0.012) levels after 12 weeks of treatment. The changes in BDNF levels are negatively correlated with the changes in TNF-α levels (r = -0.37, P = 0.03) but not with the changes in CRP and IL-6 levels. Our findings provide suggestive evidence that omega-3 fatty acids have beneficial effects on cognitive function in patients with MetS, which is paralleled by enhanced BDNF levels.

Healthy brain, healthy life: a review of diet and exercise interventions to promote brain health and reduce Alzheimer's disease risk

With the world's population aging at a rapid rate, the prevalence of Alzheimer's disease (AD) has significantly increased. These statistics are alarming given recent evidence that a third of dementia cases may be preventable. The role of lifestyle factors, such as diet and exercise, can directly alter the risk of disease development. However, an understanding of the effectiveness of dietary patterns and exercise strategies to reduce AD risk or improve brain function is not fully understood. The aim of this review is to discuss the effects of diet and exercise on AD risk. Key components of the Western and Mediterranean diets are discussed in relation to AD progression, as well as how physical activity promotes brain health. Components of the Western diet (saturated fatty acids and simple carbohydrates) are detrimental to the brain, impair cognition, and increase AD pathologies. While components of the Mediterranean diet (polyunsaturated fatty acids, polyphenols, and antioxidants) are considered to be neuroprotective. Exercise can significantly reduce the risk of AD; however, specific exercise recommendations for older adults are limited and optimal intensity, duration, and type remains unknown. This review highlights important modifiable risk factors for AD and points out potential avenues for future research. Novelty Diet and exercise are modifiable factors that can improve brain health and reduce the risk of AD. Polyunsaturated fatty acids, polyphenols, and antioxidants are neuroprotective. Exercise reduces neuroinflammation, improves brain insulin sensitivity, and increases brain derived neurotrophic factor.