A high-fat diet impairs cardiac high-energy phosphate metabolism and cognitive function in healthy human subjects

Strawberries modestly improve cognition and cardiovascular health in older adults

BACKGROUND AND AIMS

Strawberry consumption may aid in improving cognitive function and cardiovascular health given their nutrient composition and antioxidant capacities. We hypothesized that 2 cups of fresh strawberries per day provided as a freeze-dried strawberry powder (26 g/d) may improve cognitive performance and cardiovascular health relative to a control.

METHODS AND RESULTS

Using a randomized, crossover, double-blind, placebo-controlled clinical trial, 35 healthy older adults (17 women, 18 men, age 72 ± 6 years, BMI 26.4 ± 3.9 kg/m2) consumed 26 g of freeze-dried strawberry powder (strawberry) and a control powder (control) daily for 8 weeks each with a 4-week washout period. Strawberry supplementation was expected to improve cardiometabolic health parameters, and cognitive performance measured with the National Institutes of Health Toolbox. Processing speed (p < 0.001) improved during the strawberry phase and episodic memory (p = 0.002) improved during the control phase. For cardiovascular measures, strawberry consumption reduced systolic blood pressure (p = 0.044) and a significant main effect of time for reduced waist circumference (p = 0.043) was detected. Serum triglycerides increased in the control group (p = 0.012) but not after consuming strawberries. Total antioxidant capacity significantly decreased during the control phase (p = 0.032) and significantly increased with strawberry consumption (p = 0.047).

CONCLUSION

This study demonstrated that 26 g of freeze dried strawberries improve cognitive processing speed, lower systolic blood pressure, and increase antioxidant capacity, potentially promoting cognitive function and improving cardiovascular risk factors in cognitively healthy individuals.

CLINICAL TRIAL REGISTRY

NCT04786665.

High-fat diet and neuroinflammation: The role of mitochondria

In recent years, increasing evidence has supported that high-fat diet (HFD) can induce the chronic, low-grade neuroinflammation in the brain, which is closely associated with the impairment of cognitive function. As the key organelles responsible for energy metabolism in the cell, mitochondria are believed to involved in the pathogenesis of a variety of neurological disorders. This review summarizes the current progress in the field of the relationship between HFD exposure and neurodegenerative diseases, and outline the major routines of HFD induced neuroinflammation and its pathological significance in the pathogenesis of neurodegenerative diseases. Furthermore, the article highlights the pivotal role of mitochondrial dysfunction in driving the neuroinflammation in the setting of HFD. Danger-associated molecular patterns (DAMPs) from damaged mitochondria can activate innate immune signaling pathways, while mitochondrial dysfunction itself can lead to metabolic remodeling of inflammatory cells, thus inducing neuroinflammation. More importantly, mitochondrial damage, neuroinflammation, and insulin resistance caused by HFD form a mutually reinforcing vicious cycle, ultimately leading to the death of neurons and promoting the progression of neurodegenerative diseases. Thus, in-depth elucidation of the role and underlying mechanisms of mitochondrial dysfunction in HFD-induced metabolic disorders may not only expand our understanding of the mechanistic linkages between HFD and etiology of neurodegenerative diseases, but also help develop the specific strategies for the prevention and treatment of neurodegenerative diseases.

Effect of low-carbohydrate diets on quality of life, mental health, and speed of memory in adults: a systematic review and meta-analysis of randomised controlled trials

Low-carbohydrate diets (LCD) have inconclusive impacts on psychological outcomes, quality of life (QoL), and cognition. This study summarised current evidence by searching PubMed/Medline, Scopus, and Web of Sciences until October 2024. Thirty randomised controlled trials (RCTs) were included with a total sample size of 1781 (923 in the LCD group and 853 in the control group). No significant effect of LCD on mood disturbance, depression, anxiety, QoL, or memory speed was found. Subgroup analysis, however, showed significant QoL improvement in subjects consuming ≥15% of energy from carbohydrate, and trials with follow-up over 120 days. Of note, LCD significantly increased QoL in patients with neurological disorders. However, an unfavourable decrease in memory speed was observed in adults older than 55 years, and those consuming ≥15% of energy from carbohydrate. Findings demonstrated contradictory effects of LCD on QoL, mood, mental health, and memory speed.

STUDY REGISTRATION

CRD42023452217.

Glycemic control in women with GDM: insights from a randomized controlled pilot trial on plant-based Nordic healthy diet versus moderately carbohydrate restricted diet

BACKGROUND

Gestational Diabetes Mellitus (GDM) prevalence is rising worldwide, but optimal dietary strategies remain unclear. The eMOM pilot RCT compared a plant-protein rich Healthy Nordic Diet (HND) and a moderately carbohydrate restricted diet (MCRD) and their potential effects on time in glucose target range (≤ 7.8 mmol/L, %TIR), and on newborn body composition.

METHODS

Forty-two participants were randomized to either HND (n = 20) or MCRD (n = 22) face-to-face nutritional counseling from gestational weeks (GW) 24 + 0-28 + 6 (baseline) until delivery. The HND intervention had no restriction in carbohydrate intake and emphasized plant-based protein sources and Nordic food, while the MCRD had a moderate carbohydrate restriction (~ 40% in proportion to total daily energy consumption, E%). Continuous glucose monitoring was worn for 14 days to assess glucose levels and %TIR. Blood samples for glucose and lipid metabolism and 3-day food diaries were collected at baseline and at GW 34 + 0-35 + 6. Neonatal body composition was measured by air displacement plethysmography. Difference between groups were analysed with t-test and Wilcoxon test.

RESULTS

Thirty-two women completed the study. Both groups maintained the %TIR during majority of the time (98.9 and 99.3% for MCRD and HND respectively, p = 0.921) in GW 34 + 0 - 35 + 6. The mean glucose was lower in the MCRD group compared to the HND group (5.0 SD 1.03 vs. 5.2 SD 0.96 mmol/l, p < 0.001). No differences were observed in glucose variability, lipid metabolism, gestational weight gain, or in the body composition of the newborns. HND had lower diet macronutrient adherence than the MCRD, resulting in similar macronutrient composition in both groups. The mean macronutrient intakes were fat: 40.6 vs. 39.5 E%, carbohydrate: 40.5 vs. 42.4 E%, protein: 18.9 vs. 18.1 E% for the MCRD and HND groups, respectively. The HND decreased intake of meat and increased fish consumption significantly compared to the MCRD.

CONCLUSIONS

Both a moderately restricted carbohydrate diet and a diet focused on plant-based protein effectively maintained a large time within the treatment target range in women with GDM. Further research could explore the impact of protein quantity and sources in maternal diets on glycemic control and newborn outcomes.

TRIAL REGISTRATION

The eMOM pilot trial is registered in Clinicaltrials.gov (21/09/2018, NCT03681054).

Obesity-associated memory impairment and neuroinflammation precede widespread peripheral perturbations in aged rats

BACKGROUND

Obesity and metabolic syndrome are major public health concerns linked to cognitive decline with aging. Prior work from our lab has demonstrated that short-term high fat diet (HFD) rapidly impairs memory function via a neuroinflammatory mechanism. However, the degree to which these rapid inflammatory changes are unique to the brain is unknown. Moreover, deviations in gut microbiome composition have been associated with obesity and cognitive impairment, but how diet and aging interact to impact the gut microbiome, or how rapidly these changes occur, is less clear. Thus, our study investigated the impact of HFD after two distinct consumption durations: 3 months (to model diet-induced obesity) or 3 days (to detect the rapid changes occurring with HFD) on memory function, anxiety-like behavior, central and peripheral inflammation, and gut microbiome profile in young and aged rats.

RESULTS

Our data indicated that both short-term and long-term HFD consumption impaired memory function and increased anxiety-like behavior in aged, but not young adult, rats. These behavioral changes were accompanied by pro- and anti-inflammatory cytokine dysregulation in the hippocampus and amygdala of aged HFD-fed rats at both time points. However, changes to fasting glucose, insulin, and inflammation in peripheral tissues such as the distal colon and visceral adipose tissue were increased in young and aged rats only after long-term, but not short-term, HFD consumption. Furthermore, while subtle HFD-induced changes to the gut microbiome did occur rapidly, robust age-specific effects were only present following long-term HFD consumption.

CONCLUSIONS

Overall, these data suggest that HFD-evoked neuroinflammation, memory impairment, and anxiety-like behavior in aging develop quicker than, and separately from the peripheral hallmarks of diet-induced obesity.

Advances in myocardial energy metabolism: metabolic remodelling in heart failure and beyond

The very high energy demand of the heart is primarily met by adenosine triphosphate (ATP) production from mitochondrial oxidative phosphorylation, with glycolysis providing a smaller amount of ATP production. This ATP production is markedly altered in heart failure, primarily due to a decrease in mitochondrial oxidative metabolism. Although an increase in glycolytic ATP production partly compensates for the decrease in mitochondrial ATP production, the failing heart faces an energy deficit that contributes to the severity of contractile dysfunction. The relative contribution of the different fuels for mitochondrial ATP production dramatically changes in the failing heart, which depends to a large extent on the type of heart failure. A common metabolic defect in all forms of heart failure [including heart failure with reduced ejection fraction (HFrEF), heart failure with preserved EF (HFpEF), and diabetic cardiomyopathies] is a decrease in mitochondrial oxidation of pyruvate originating from glucose (i.e. glucose oxidation). This decrease in glucose oxidation occurs regardless of whether glycolysis is increased, resulting in an uncoupling of glycolysis from glucose oxidation that can decrease cardiac efficiency. The mitochondrial oxidation of fatty acids by the heart increases or decreases, depending on the type of heart failure. For instance, in HFpEF and diabetic cardiomyopathies myocardial fatty acid oxidation increases, while in HFrEF myocardial fatty acid oxidation either decreases or remains unchanged. The oxidation of ketones (which provides the failing heart with an important energy source) also differs depending on the type of heart failure, being increased in HFrEF, and decreased in HFpEF and diabetic cardiomyopathies. The alterations in mitochondrial oxidative metabolism and glycolysis in the failing heart are due to transcriptional changes in key enzymes involved in the metabolic pathways, as well as alterations in redox state, metabolic signalling and post-translational epigenetic changes in energy metabolic enzymes. Of importance, targeting the mitochondrial energy metabolic pathways has emerged as a novel therapeutic approach to improving cardiac function and cardiac efficiency in the failing heart.

Dietary patterns related to attention and physiological function in high-altitude migrants

High altitude exposure negatively affects human attentional function. However, no studies have explored the regulation of attentional and physiological functions from a dietary perspective. A total of 116 Han Chinese students from Tibet University who were born and raised in a plain area and had been living in Tibet for > 2 years were recruited. All participants were male migrants. A food frequency questionnaire, complete blood count, and attention network test were performed on the participants. Pearson's correlation was applied to assess the reliability and validity of the food frequency questionnaire. Principal component analysis was utilized to extract dietary patterns. A linear mixed model was employed to account for individual differences. The results showed that the five main dietary patterns were coarse grain, alcohol, meat, protein, and snacking dietary patterns. Furthermore, individuals who adhered to the coarse grain dietary pattern and had high mean corpuscular hemoglobin showed better attentional performance. Individuals with high alcohol consumption and systemic immune-inflammation index levels exhibited worse attentional performance. These findings imply that high-altitude migrants should include more coarse grains in their daily diet and avoid excessive alcohol consumption to improve attention.

High-fat diet consumption negatively influences closed-head traumatic brain injury in a pediatric rodent model

Traumatic brain injury (TBI) is one of the most common causes of emergency room visits in children, and it is a leading cause of death in juveniles in the United States. Similarly, a high proportion of this population consumes diets that are high in saturated fats, and millions of children are overweight or obese. The goal of the present study was to assess the relationship between diet and TBI on cognitive and cerebrovascular outcomes in juvenile rats. In the current study, groups of juvenile male Long Evans rats were subjected to either mild TBI via the Closed-Head Injury Model of Engineered Rotational Acceleration (CHIMERA) or underwent sham procedures. The animals were provided with either a combination of high-fat diet and a mixture of high-fructose corn syrup (HFD/HFCS) or a standard chow diet (CH) for 9 days prior to injury. Prior to injury, the animals were trained on the Morris water maze for three consecutive days, and they underwent a post-injury trial on the day of the injury. Immediately after TBI, the animals' righting reflexes were tested. Four days post-injury, the animals were euthanized, and brain samples and blood plasma were collected for qRT-PCR, immunohistochemistry, and triglyceride assays. Additional subsets of animals were used to investigate cerebrovascular perfusion using Laser Speckle and perform immunohistochemistry for endothelial cell marker RECA. Following TBI, the righting reflex was significantly increased in TBI rats, irrespective of diet. The TBI worsened the rats' performance in the post-injury trial of the water maze at 3 h, p(injury) < 0.05, but not at 4 days post-injury. Reduced cerebrovascular blood flow using Laser Speckle was demonstrated in the cerebellum, p(injury) < 0.05, but not foci of the cerebral cortices or superior sagittal sinus. Immunoreactive staining for RECA in the cortex and corpus callosum was significantly reduced in HFD/HFCS TBI rats, p < 0.05. qRT-PCR showed significant increases in APOE, CREB1, FCGR2B, IL1B, and IL6, particularly in the hippocampus. The results from this study offer robust evidence that HFD/HFCS negatively influences TBI outcomes with respect to cognition and cerebrovascular perfusion of relevant brain regions in the juvenile rat.

Human cardiac metabolism

The heart is the most metabolically active organ in the human body, and cardiac metabolism has been studied for decades. However, the bulk of studies have focused on animal models. The objective of this review is to summarize specifically what is known about cardiac metabolism in humans. Techniques available to study human cardiac metabolism are first discussed, followed by a review of human cardiac metabolism in health and in heart failure. Mechanistic insights, where available, are reviewed, and the evidence for the contribution of metabolic insufficiency to heart failure, as well as past and current attempts at metabolism-based therapies, is also discussed.

Gut microbiota and cognitive performance: A bidirectional two-sample Mendelian randomization

PURPOSE

Previous studies have suggested a potential association between gut microbiota and neurological and psychiatric disorders. However, the causal relationship between gut microbiota and cognitive performance remains uncertain.

METHODS

A two-sample Mendelian randomization (MR) study used SNPs linked to gut microbiota (n = 18,340) and cognitive performance (n = 257,841) from recent GWAS data. Inverse-variance weighted (IVW), MR Egger, weighted median, simple mode, and weighted mode were employed. Heterogeneity was assessed via Cochran's Q test for IVW. Results were shown with funnel plots. Outliers were detected through leave-one-out method. MR-PRESSO and MR-Egger intercept tests were conducted to address horizontal pleiotropy influence.

LIMITATIONS

Limited to European populations, generic level, and potential confounding factors.

RESULTS

IVW analysis revealed detrimental effects on cognitive perfmance associated with the presence of genus Blautia (P = 0.013, 0.966[0.940-0.993]), Catenibacterium (P = 0.035, 0.977[0.956-0.998]), Oxalobacter (P = 0.043, 0.979[0.960-0.999]). Roseburia (P < 0.001, 0.935[0.906-0.965]), in particular, remained strongly negatively associated with cognitive performance after Bonferroni correction. Conversely, families including Bacteroidaceae (P = 0.043, 1.040[1.001-1.081]), Rikenellaceae (P = 0.047, 1.026[1.000-1.053]), along with genera including Paraprevotella (P = 0.044, 1.020[1.001-1.039]), Ruminococcus torques group (P = 0.016, 1.062[1.011-1.115]), Bacteroides (P = 0.043, 1.040[1.001-1.081]), Dialister (P = 0.027, 1.039[1.004-1.074]), Paraprevotella (P = 0.044, 1.020[1.001-1.039]) and Ruminococcaceae UCG003 (P = 0.007, 1.040[1.011-1.070]) had a protective effect on cognitive performance.

CONCLUSIONS

Our results suggest that interventions targeting specific gut microbiota may offer a promising avenue for improving cognitive function in diseased populations. The practical application of these findings has the potential to enhance cognitive performance, thereby improving overall quality of life.

A mediation analysis of the role of total free fatty acids on pertinence of gut microbiota composition and cognitive function in late life depression

BACKGROUND

Extensive evidence demonstrates correlations among gut microbiota, lipid metabolism and cognitive function. However, there is still a lack of researches in the field of late-life depression (LLD). This research targeted at investigating the relationship among gut microbiota, lipid metabolism indexes, such as total free fatty acids (FFAs), and cognitive functions in LLD.

METHODS

Twenty-nine LLD patients from the Cognitive Outcome Cohort Study of Depression in Elderly were included. Cognitive functions were estimated through the Chinese version of Montreal Cognitive Assessment (MoCA). Blood samples were collected to evaluate serum lipid metabolism parameters. Fecal samples were evaluated for gut microbiota determination via 16S rRNA sequencing. Spearman correlation, linear regression and mediation analysis were utilized to explore relationship among gut microbiota, lipid metabolism and cognitive function in LLD patients.

RESULTS

Spearman correlation analysis revealed significant correlations among Akkermansia abundance, total Free Fatty Acids (FFAs) and MoCA scores (P < 0.05). Multiple regression indicated Akkermansia and total FFAs significantly predicted MoCA scores (P < 0.05). Mediation analysis demonstrated that the correlation between decreased Akkermansia relative abundance and cognitive decline in LLD patients was partially mediated by total FFAs (Bootstrap 95%CI: 0.023-0.557), accounting for 43.0% of the relative effect.

CONCLUSION

These findings suggested a significant relationship between cognitive functions in LLD and Akkermansia, as well as total FFAs. Total FFAs partially mediated the relationship between Akkermansia and cognitive functions. These results contributed to understanding the gut microbial-host lipid metabolism axis in the cognitive function of LLD.

Prolonged Early Exposure to a High-Fat Diet Augments the Adverse Effects on Neurobehavior and Hippocampal Neuroplasticity: Involvement of Microglial Insulin Signaling

High-fat diet (HFD) consumption may contribute to the high prevalence of cognitive-emotional issues in modern society. Mice fed a HFD for a prolonged period develop more severe neurobehavioral disturbances when first exposed to a HFD in the juvenile period than in adulthood, suggesting an initial age-related difference in the detrimental effects of long-term HFD feeding. However, the mechanism underlying this difference remains unclear. Here, male C57BL/6J mice initially aged 4 (IA4W) or 8 (IA8W) weeks were fed a control diet (CD) or HFD for 6 months and then subjected to metabolic, neurobehavioral, and histomorphological examinations. Although the detrimental effects of long-term HFD feeding on metabolism and neurobehavior were observed in mice of both ages, IA4W-HFD mice showed significant cognitive inflexibility accompanied by significantly greater levels of anxiety-like behavior than age-matched controls. Hippocampal neuroplasticity and microglial phenotype were altered by HFD feeding, whereas significant morphological alterations were more frequently observed in IA4W-HFD mice than in IA8W-HFD mice. Additionally, significantly increased hippocampal microglial engulfment of postsynaptic proteins and elevated phospho-insulin-receptor levels were observed in IA4W-HFD, but not in IA8W-HFD, mice. These findings suggest that aberrant microglia-related histomorphological changes in the hippocampus underlie the exacerbated detrimental neurobehavioral effects of prolonged early HFD exposure and indicate that enhanced insulin signaling might drive microglial dysfunction after prolonged early HFD exposure.

Short-term high-fat diet consumption impairs synaptic plasticity in the aged hippocampus via IL-1 signaling

More Americans are consuming diets higher in saturated fats and refined sugars than ever before. These trends could have serious consequences for the older population because high-fat diet (HFD) consumption, known to induce neuroinflammation, has been shown to accelerate and aggravate memory declines. We have previously demonstrated that short-term HFD consumption, which does not evoke obesity-related comorbidities, produced profound impairments to hippocampal-dependent memory in aged rats. These impairments were precipitated by increases in proinflammatory cytokines, primarily interleukin-1 beta (IL-1β). Here, we explored the extent to which short-term HFD consumption disrupts hippocampal synaptic plasticity, as measured by long-term potentiation (LTP), in young adult and aged rats. We demonstrated that (1) HFD disrupted late-phase LTP in the hippocampus of aged, but not young adult rats, (2) HFD did not disrupt early-phase LTP, and (3) blockade of the IL-1 receptor rescued L-LTP in aged HFD-fed rats. These findings suggest that hippocampal memory impairments in aged rats following HFD consumption occur through the deterioration of synaptic plasticity and that IL-1β is a critical driver of that deterioration.

Obesogenic Diet Cycling Produces Graded Effects on Cognition and Microbiota Composition in Rats

SCOPE

The effects of diet cycling on cognition and fecal microbiota are not well understood.

METHOD AND RESULTS

Adult male Sprague-Dawley rats were cycled between a high-fat, high-sugar "cafeteria" diet (Caf) and regular chow. The impairment in place recognition memory produced by 16 days of Caf diet was reduced by switching to chow for 11 but not 4 days. Next, rats received 16 days of Caf diet in 2, 4, 8, or 16-day cycles, each separated by 4-day chow cycles. Place recognition memory declined from baseline in all groups and was impaired in the 16- versus 2-day group. Finally, rats received 24 days of Caf diet continuously or in 3-day cycles separated by 2- or 4-day chow cycles. Any Caf diet access impaired cognition and increased adiposity relative to controls, without altering hippocampal gene expression. Place recognition and adiposity were the strongest predictors of global microbiota composition. Overall, diets with higher Caf > chow ratios produced greater spatial memory impairments and larger shifts in gut microbiota species richness and beta diversity.

CONCLUSION

Results suggest that diet-induced cognitive deficits worsen in proportion to unhealthy diet exposure, and that shifting to a healthy chow for at least a week is required for recovery under the conditions tested here.

Effect of High Fat Diet on Disease Development of Polycystic Ovary Syndrome and Lifestyle Intervention Strategies

Polycystic ovary syndrome (PCOS) is a prevalent endocrine and metabolic disorder that affects premenopausal women. The etiology of PCOS is multifaceted, involving various genetic and epigenetic factors, hypothalamic-pituitary-ovarian dysfunction, androgen excess, insulin resistance, and adipose-related mechanisms. High-fat diets (HFDs) has been linked to the development of metabolic disorders and weight gain, exacerbating obesity and impairing the function of the hypothalamic-pituitary-ovarian axis. This results in increased insulin resistance, hyperinsulinemia, and the release of inflammatory adipokines, leading to heightened fat synthesis and reduced fat breakdown, thereby worsening the metabolic and reproductive consequences of PCOS. Effective management of PCOS requires lifestyle interventions such as dietary modifications, weight loss, physical activity, and psychological well-being, as well as medical or surgical interventions in some cases. This article systematically examines the pathological basis of PCOS and the influence of HFDs on its development, with the aim of raising awareness of the connection between diet and reproductive health, providing a robust approach to lifestyle interventions, and serving as a reference for the development of targeted drug treatments.

Something to Snack on: Can Dietary Modulators Boost Mind and Body?

The last decades have shown that maintaining a healthy and balanced diet can support brain integrity and functionality, while an inadequate diet can compromise it. However, still little is known about the effects and utility of so-called healthy snacks or drinks and their immediate short-term effects on cognition and physical performance. Here, we prepared dietary modulators comprising the essential macronutrients at different ratios and a controlled balanced dietary modulator. We assessed, in healthy adult mice, the short-term effects of these modulators when consumed shortly prior to tests with different cognitive and physical demands. A high-fat dietary modulator sustained increased motivation compared to a carbohydrate-rich dietary modulator (p = 0.041) which had a diminishing effect on motivation (p = 0.018). In contrast, a high-carbohydrate modulator had an initial beneficial effect on cognitive flexibility (p = 0.031). No apparent effects of any of the dietary modulators were observed on physical exercise. There is increasing public demand for acute cognitive and motor function enhancers that can improve mental and intellectual performance in daily life, such as in the workplace, studies, or sports activities. Our findings suggest such enhancers should be tailored to the cognitive demand of the task undertaken, as different dietary modulators will have distinct effects when consumed shortly prior to the task.

Metabolic and Transcriptomic Changes in the Mouse Brain in Response to Short-Term High-Fat Metabolic Stress

The chronic consumption of diets rich in saturated fats leads to obesity and associated metabolic disorders including diabetes and atherosclerosis. Intake of a high-fat diet (HFD) is also recognized to dysregulate neural functions such as cognition, mood, and behavior. However, the effects of short-term high-fat diets on the brain are elusive. Here, we investigated molecular changes in the mouse brain following an acute HFD for 10 days by employing RNA sequencing and metabolomics profiling. Aberrant expressions of 92 genes were detected in the brain tissues of acute HFD-exposed mice. The differentially expressed genes were enriched for various pathways and processes such as superoxide metabolism. In our global metabolomic profiling, a total of 59 metabolites were significantly altered by the acute HFD. Metabolic pathways upregulated from HFD-exposed brain tissues relative to control samples included oxidative stress, oxidized polyunsaturated fatty acids, amino acid metabolism (e.g., branched-chain amino acid catabolism, and lysine metabolism), and the gut microbiome. Acute HFD also elevated levels of N-acetylated amino acids, urea cycle metabolites, and uracil metabolites, further suggesting complex changes in nitrogen metabolism. The observed molecular events in the present study provide a valuable resource that can help us better understand how acute HFD stress impacts brain homeostasis.

The Role of Gut Microbiota in High-Fat-Diet-Induced Diabetes: Lessons from Animal Models and Humans

The number of diabetes mellitus patients is increasing rapidly worldwide. Diet and nutrition are strongly believed to play a significant role in the development of diabetes mellitus. However, the specific dietary factors and detailed mechanisms of its development have not been clearly elucidated. Increasing evidence indicates the intestinal microbiota is becoming abundantly apparent in the progression and prevention of insulin resistance in diabetes. Differences in gut microbiota composition, particularly butyrate-producing bacteria, have been observed in preclinical animal models as well as human patients compared to healthy controls. Gut microbiota dysbiosis may disrupt intestinal barrier functions and alter host metabolic pathways, directly or indirectly relating to insulin resistance. In this article, we focus on dietary fat, diabetes, and gut microbiome characterization. The promising probiotic and prebiotic approaches to diabetes, by favorably modifying the composition of the gut microbial community, warrant further investigation through well-designed human clinical studies.

Cardiac metabolism in HFpEF: from fuel to signalling

Heart failure (HF) is marked by distinctive changes in myocardial uptake and utilization of energy substrates. Among the different types of HF, HF with preserved ejection fraction (HFpEF) is a highly prevalent, complex, and heterogeneous condition for which metabolic derangements seem to dictate disease progression. Changes in intermediate metabolism in cardiometabolic HFpEF-among the most prevalent forms of HFpEF-have a large impact both on energy provision and on a number of signalling pathways in the heart. This dual, metabolic vs. signalling, role is played in particular by long-chain fatty acids (LCFAs) and short-chain carbon sources [namely, short-chain fatty acids (SCFAs) and ketone bodies (KBs)]. LCFAs are key fuels for the heart, but their excess can be harmful, as in the case of toxic accumulation of lipid by-products (i.e. lipotoxicity). SCFAs and KBs have been proposed as a potential major, alternative source of energy in HFpEF. At the same time, both LCFAs and short-chain carbon sources are substrate for protein post-translational modifications and other forms of direct and indirect signalling of pivotal importance in HFpEF pathogenesis. An in-depth molecular understanding of the biological functions of energy substrates and their signalling role will be instrumental in the development of novel therapeutic approaches to HFpEF. Here, we summarize the current evidence on changes in energy metabolism in HFpEF, discuss the signalling role of intermediate metabolites through, at least in part, their fate as substrates for post-translational modifications, and highlight clinical and translational challenges around metabolic therapy in HFpEF.

Implication of saturated fats in the aetiology of childhood attention deficit/hyperactivity disorder - A narrative review

Attention Deficit/Hyperactivity Disorder (ADHD) is the most common mental health disorder in the paediatric population. ADHD is highly comorbid with obesity, and has also been associated with poor dietary patterns such as increased consumption of refined carbohydrates and saturated fats. Although ADHD in children was associated with high consumption of saturated fats, so far there has been no evidence-based attempt to integrate dietary strategies controlling for intake of saturated fats into the etiological framework of the disorder. Evidence from human studies and animal models has shown that diets high in saturated fats are detrimental for the development of dopaminergic neurocircuitries, synthesis of neurofactors (e.g. brain derived neurotrophic factor) and may promote brain inflammatory processes. Notably, animal models provide evidence that early life consumption of a high saturated fats diet may impair the development of central dopamine pathways. In the present paper, we review the impact of high saturated fats diets on neurobiological processes in human studies and animal models, and how these associations may be relevant to the neuropathophysiology of ADHD in children. The validation of this relationship and its underlying mechanisms through future investigative studies could have implications for the prevention or exacerbation of ADHD symptoms, improve the understanding of the pathogenesis of the disorder, and help design future dietary studies in patients with ADHD.

Sodium-glucose cotransporter 2 inhibitor ameliorates high fat diet-induced hypothalamic-pituitary-ovarian axis disorders

High-fat diet (HFD) consumption is known to be associated with ovulatory disorders among women of reproductive age. Previous studies in animal models suggest that HFD-induced microglia activation contributes to hypothalamic inflammation. This causes the dysfunction of the hypothalamic-pituitary-ovarian (HPO) axis, leading to subfertility. Sodium-glucose cotransporter 2 (SGLT2) inhibitors are a novel class of lipid-soluble antidiabetic drugs that target primarily the early proximal tubules in kidney. Recent evidence revealed an additional expression site of SGLT2 in the central nervous system (CNS), indicating a promising role of SGLT2 inhibitors in the CNS. In type 2 diabetes patients and rodent models, SGLT2 inhibitors exhibit neuroprotective properties through reduction of oxidative stress, alleviation of cerebral atherosclerosis and suppression of microglia-induced neuroinflammation. Furthermore, clinical observations in patients with polycystic ovary syndrome (PCOS) demonstrated that SGLT2 inhibitors ameliorated patient anthropometric parameters, body composition and insulin resistance. Therefore, it is of importance to explore the central mechanism of SGLT2 inhibitors in the recovery of reproductive function in patients with PCOS and obesity. Here, we review the hypothalamic inflammatory mechanisms of HFD-induced microglial activation, with a focus on the clinical utility and possible mechanism of SGLT2 inhibitors in promoting reproductive fitness.

(-)-Epicatechin exerts positive effects on anxiety in high fat diet-induced obese mice through multi-genomic modifications in the hippocampus

Obesity is associated with increased occurrence of cognitive and mood disorders. While consumption of high-fat diets (HFD) and associated obesity could have a detrimental impact on the brain, dietary bioactives may mitigate these harmful effects. We previously observed that (-)-epicatechin (EC) can mitigate HFD-induced anxiety-associated behaviors in mice. The aim of our study is to investigate the molecular mechanisms of EC actions in the hippocampus which underlies its anti-anxiety effects in HFD-fed mice using a multi-genomic approach. Healthy eight-week old male C57BL/6J mice were fed for 24 weeks either: (A) a control diet containing 10% total calories from fat; (B) a HFD containing 45% total calories from fat; or (C) the HFD supplemented with 20 mg EC per kg body weight. Hippocampi were isolated for genomic analysis using Affymetrix arrays, followed by in-depth bioinformatic analyses. Genomic analysis demonstrated that EC induced significant changes in mouse hippocampal global gene expression. We observed changes in the expression of 1001 protein-coding genes, 241 miRNAs, and 167 long non-coding RNAs. Opposite gene expression profiles were observed when the gene expression profile obtained upon EC supplementation was compared to the profile obtained after consumption of the HFD. Functionality analysis revealed that the differentially expressed genes regulate processes involved in neurofunction, inflammation, endothelial function, cell-cell adhesion, and cell signaling. In summary, the capacity of EC to mitigate anxiety-related behaviors in HFD-induced obese mice can be in part explained by its capacity to exert complex genomic modifications in the hippocampus, counteracting changes driven by consumption of the HFD and/or associated obesity.

Olive- and Coconut-Oil-Enriched Diets Decreased Secondary Bile Acids and Regulated Metabolic and Transcriptomic Markers of Brain Injury in the Frontal Cortexes of NAFLD Pigs

The objective of this study was to investigate the effect of dietary fatty acid (FA) saturation and carbon chain length on brain bile acid (BA) metabolism and neuronal number in a pig model of pediatric NAFLD. Thirty 20-day-old Iberian pigs, pair-housed in pens, were randomly assigned to receive one of three hypercaloric diets for 10 weeks: (1) lard-enriched (LAR; n = 5 pens), (2) olive-oil-enriched (OLI, n = 5), and (3) coconut-oil-enriched (COC; n = 5). Pig behavior and activity were analyzed throughout the study. All animals were euthanized on week 10 and frontal cortex (FC) samples were collected for immunohistochemistry, metabolomic, and transcriptomic analyses. Data were analyzed by multivariate and univariate statistics. No differences were observed in relative brain weight, neuronal number, or cognitive functioning between diets. Pig activity and FC levels of neuroprotective secondary BAs and betaine decreased in the COC and OLI groups compared with LAR, and paralleled the severity of NAFLD. In addition, OLI-fed pigs showed downregulation of genes involved in neurotransmission, synaptic transmission, and nervous tissue development. Similarly, COC-fed pigs showed upregulation of neurogenesis and myelin repair genes, which caused the accumulation of medium-chain acylcarnitines in brain tissue. In conclusion, our results indicate that secondary BA levels in the FCs of NAFLD pigs are affected by dietary FA composition and are associated with metabolic and transcriptomic markers of brain injury. Dietary interventions that aim to replace saturated FAs by medium-chain or monounsaturated FAs in high-fat hypercaloric diets may have a negative effect on brain health in NAFLD patients.

Combined exposure of lead and high-fat diet enhanced cognitive decline via interacting with CREB-BDNF signaling in male rats

The health risks to populations induced by lead (Pb) and high-fat diets (HFD) have become a global public health problem. Pb and HFD often co-exist and are co-occurring risk factors for cognitive impairment. This study investigates effect of combined Pb and HFD on cognitive function, and explores the underlying mechanisms in terms of regulatory components of synaptic plasticity and insulin signaling pathway. We showed that the co-exposure of Pb and HFD further increased blood Pb levels, caused body weight loss and dyslipidemia. The results from Morris water maze (MWM) test and Nissl staining disclosed that Pb and HFD each contributed to cognitive deficits and neuronal damage and combined exposure enhanced this toxic injury. Pb and HFD decreased the levels of synapsin-1, GAP-43 and PSD-95 protein related to synaptic properties and SIRT1, NMDARs, phosphorylated CREB and BDNF related to synaptic plasticity regulatory, and these decreases was greater when combined exposure. Additionally, we revealed that Pb and HFD promoted IRS-1 phosphorylation and subsequently reduced downstream PI3K-Akt kinases phosphorylation in hippocampus and cortex of rats, and this process was aggravated when co-exposure. Collectively, our data suggested that combined exposure of Pb and HFD enhanced cognitive deficits, pointing to additive effects in rats than the individual stress effects related to multiple signaling pathways with CREB-BDNF signaling as the hub. This study emphasizes the need to evaluate the effects of mixed exposures on brain function in realistic environment and to better inform prevention of neurological disorders via modulating central pathway, such as CREB/BDNF signaling.

Liuwei Dihuang Decoction Alleviates Cognitive Dysfunction in Mice With D-Galactose-Induced Aging by Regulating Lipid Metabolism and Oxidative Stress via the Microbiota-Gut-Brain Axis

Background

Aging is an important cause of cognitive dysfunction. Liuwei Dihuang decoction (LW), a commonly applied Chinese medicine formula, is widely used for the treatment of aging-related diseases in China. Previously, LW was confirmed to be effective in prolonging life span and reducing oxidative stress in aged mice. Unfortunately, the underlying mechanism of LW remains unclear. The aim of this study was to interpret the mechanism by which LW alleviates cognitive dysfunction related to aging from the perspective of the microbiota-gut-brain axis.

Method

All C57BL/6 mice (n = 60) were randomly divided into five groups: the control, model, vitamin E (positive control group), low-dose LW and high-dose LW groups (n = 12 in each group). Except for those in the control group, D-galactose was subcutaneously injected into mice in the other groups to induce the aging model. The antiaging effect of LW was evaluated by the water maze test, electron microscopy, 16S rRNA sequencing, combined LC–MS and GC–MS metabolomics, and ELISA.

Results

Liuwei Dihuang decoction ameliorated cognitive dysfunction and hippocampal synaptic ultrastructure damage in aging mice. Moreover, LW decreased Proteobacteria abundance and increased gut microbiota diversity in aging mice. Metabolomic analysis showed that LW treatment was associated with the significantly differential abundance of 14 metabolites, which were mainly enriched in apelin signaling, sphingolipid metabolism, glycerophospholipid and other metabolic pathways. Additionally, LW affected lipid metabolism and oxidative stress in aging mice. Finally, we also found that LW-regulated microbial species such as Proteobacteria and Fibrobacterota had potential relationships with lipid metabolism, oxidative stress and hippocampal metabolites.

Conclusion

In brief, LW improved cognitive function in aging mice by regulating lipid metabolism and oxidative stress through restoration of the homeostasis of the microbiota-gut-brain axis.

Hedgehog Signal Defect Leading to Familial Exudative Vitreoretinopathy-Like Disease and Gastrointestinal Malformation

Objectives:

The aim of the study was to present a new genetic association presenting with gastrointestinal tract malformations (GTMs) and familial exudative vitreoretinopathy (FEVR)-like disease and review the genetics of Hedgehog signaling.

Materials and Methods:

Three neonates were diagnosed with FEVR-like retinal vascular disease upon routine ophthalmological examination during hospitalization in the neonatal surgical intensive care unit for GTMs. Genetic analysis of the neonates was performed.

Results:

Gestational age of the neonates was 39, 38, and 39 weeks and birth weights were 3,500, 3,600, and 3,300 grams, respectively. All six eyes of the three infants were treated by laser photocoagulation. Recurrence was not seen in any of the eyes. Genetical analysis of all the neonates diagnosed with FEVR-like disease revealed defects in the Hedgehog pathway.

Conclusion:

FEVR is a genetically well-defined retinal vascular disease. The current study is the first to show an association between FEVR-like retinal vascular disease and GTMs. This study demonstrates the importance of the Hedgehog pathway in retinal vascular and gut development.

Cognitive, Sleep, and Autonomic Responses to Induction of a Ketogenic Diet in Military Personnel: A Pilot Study

BACKGROUND: This pilot study examined the effect of a 2-wk ketogenic diet (KD) compared with a carbohydrate (CHO) diet in military personnel on cognitive performance, mood, sleep, and heart rate variability (HRV).METHODS: A randomized-controlled, cross-over trial was conducted with eight male military personnel (age, 36 ± 7 yr; body mass, 83.7 ± 9.2 kg; BMI, 26.0 ± 2.3 kg · m−2). Subjects ingested their habitual diet for 7 d (baseline), then an iso-energetic KD (∼25 g CHO/d) or CHO diet (∼285 g CHO/d) for 14 d (adaptation), separated by a 12-d washout. HRV, fasting capillary blood D-βHB, and glucose concentration, mood, and sleep were measured daily. Cognitive performance was measured on the 7th day of baseline and the 7th and 14th days of adaptation. Data were analyzed using a series of linear mixed models.RESULTS: Mean weekly D-βHB was higher (95% CI, +0.34 to +2.38 mmol · L−1) and glucose was lower (−0.45 to −0.21 mmol · L−1) in the KD compared with the CHO diet. Cognitive performance (Psychomotor Vigilance Task, 2-choice reaction time, and running memory continuous performance test) and mean weekly fatigue, vigor, and sleep (sleep duration, sleep efficiency, and sleep onset latency) were similar between diets. A diet × week interaction for HRV approached significance, with exploratory analyses suggesting HRV was lower compared with baseline during week-2 adapt (−27 to +4 ms) in the KD.DISCUSSION: A 2-wk induction to a KD in male military personnel does not appear to affect cognitive performance, mood, or sleep, but may lower HRV, indicating increased physiological stress.Shaw DM, Henderson L, van den Berg M. Cognitive, sleep, and autonomic responses to induction of a ketogenic diet in military personnel: a pilot study. Aerosp Med Hum Perform. 2022; 93(6):507–516.

The Effect of Dietary Fat and Sucrose on Cognitive Functioning in Mice Lacking Insulin Signaling in Neuropeptide Y Neurons

Obesogenic diets can produce hippocampal insulin resistance and impairments to hippocampal-dependent cognition. This study investigated the effect of disrupted insulin signaling in Neuropeptide Y (NPY) neurons on diet-induced deficits in hippocampal-dependent memory. Wild-type mice and mice that had a targeted knockout of insulin receptors on NPY cells (IR^lox/lox;NPY^Cre/+) were given ad libitum access to a high-fat diet (high fat; HF), 10% sucrose solution (high sugar; HS), both high-fat diet and sucrose solution (high fat, high sugar; HFHS), or a normal fat control chow for 12 weeks. Mice were tested in the Morris Water Maze (MWM), a hippocampal-dependent spatial memory task. Glucose homeostasis was assessed via a glucose tolerance test. Independent of genotype, consumption of HF, but not HS, diet increased energy intake, body weight, and plasma leptin, and impaired glucose tolerance. Disrupted insulin signaling in NPY cells and dietary interventions did not significantly affect the ability of mice to learn the location of the platform in the MWM. However, for IR^lox/lox control mice, consumption of HF, but not HS, diet resulted in reduced time spent in the target quadrant during the probe trial, suggesting a hippocampal-dependent memory deficit. IR^lox/lox;NPY^Cre/+ mice had poor performance in the probe trial regardless of diet, suggesting a floor effect. This study did not find adverse effects of chronic sucrose intake on metabolic outcomes or hippocampal-dependent memory. These data also suggest that the effects of HF diet on hippocampal-dependent memory may be dependent on insulin signaling in hippocampal NPY cells.

Dysmetabolism and Neurodegeneration: Trick or Treat?

Accumulating evidence suggests the existence of a strong link between metabolic syndrome and neurodegeneration. Indeed, epidemiologic studies have described solid associations between metabolic syndrome and neurodegeneration, whereas animal models contributed for the clarification of the mechanistic underlying the complex relationships between these conditions, having the development of an insulin resistance state a pivotal role in this relationship. Herein, we review in a concise manner the association between metabolic syndrome and neurodegeneration. We start by providing concepts regarding the role of insulin and insulin signaling pathways as well as the pathophysiological mechanisms that are in the genesis of metabolic diseases. Then, we focus on the role of insulin in the brain, with special attention to its function in the regulation of brain glucose metabolism, feeding, and cognition. Moreover, we extensively report on the association between neurodegeneration and metabolic diseases, with a particular emphasis on the evidence observed in animal models of dysmetabolism induced by hypercaloric diets. We also debate on strategies to prevent and/or delay neurodegeneration through the normalization of whole-body glucose homeostasis, particularly via the modulation of the carotid bodies, organs known to be key in connecting the periphery with the brain.

How to preserve healthy aging through nutritional strategies: The new approach of the Food Social Network (Food NET) project

BACKGROUND: Aging is a process that does not refer only to the accumulation of damage in a human being over time but rather to individual changes determined by genetic, lifestyle, social and environmental factors. Aging is one of the greatest known risk factors for most human diseases. An older person in good health has a good level of independence, weighs less on the national health system and plays a productive and active role in his/her community; thus, the concept of “healthy aging”, reflecting older adult-environment fit should be promoted. The interactions between lifestyle, including nutrition, and health play a fundamental role in the aging process; eating habits and eating behaviours are recognized as important modifiable factors potentially leading to a healthy “phenotype”. OBJECTIVE AND METHODS: A multidisciplinary consortium with three Italian universities (the University of Milano-Bicocca, University of Pavia and University of Calabria) and Italian Small-Medium Enterprises proposed the Food Social Network (Food NET) project. Food NET overall outcome is to achieve target-specific guidelines and exact technologies for accessible functional foods, aimed at improving the quality of life and nutritional status of citizens (aged>65) of the Metropolitan City of Milan (Italy). CONCLUSIONS: This project is part of the “Smart Living” and food-related strategies aimed at responding to the needs of this target population, developing new food products, appropriate to meet the specific requirements and ensuring and promoting sustainable diets for healthy aging by effective food policy approaches.

Short-Chain Carbon Sources

Heart failure (HF) remains the leading cause of morbidity and mortality in the developed world, highlighting the urgent need for novel, effective therapeutics. Recent studies support the proposition that improved myocardial energetics as a result of ketone body (KB) oxidation may account for the intriguing beneficial effects of sodium-glucose cotransporter-2 inhibitors in patients with HF. Similar small molecules, short-chain fatty acids (SCFAs) are now realized to be preferentially oxidized over KBs in failing hearts, contradicting the notion of KBs as a rescue "superfuel." In addition to KBs and SCFAs being alternative fuels, both exert a wide array of nonmetabolic functions, including molecular signaling and epigenetics and as effectors of inflammation and immunity, blood pressure regulation, and oxidative stress. In this review, the authors present a perspective supported by new evidence that the metabolic and unique nonmetabolic activities of KBs and SCFAs hold promise for treatment of patients with HF with reduced ejection fraction and those with HF with preserved ejection fraction.

Effect of MIND diet intervention on cognitive performance and brain structure in healthy obese women: a randomized controlled trial

Previous studies suggested adherence to recently developed Mediterranean-DASH Intervention for Neurodegenerative Delay (MIND) associated with cognitive performance. This study aimed to examine the effect of MIND dietary pattern on cognitive performance features and changes in brain structure in healthy obese women. As a total of 50 obese women were assessed for eligibility, we randomly allocated 40 participants with mean BMI 32 ± 4.31 kg/m2 and mean age 48 ± 5.38 years to either calorie-restricted modified MIND diet or a calorie-restricted standard control diet. Change in cognitive performance was the primary outcome measured with a comprehensive neuropsychological test battery. We also performed voxel-based morphometry as a secondary outcome to quantify the differences in brain structure. All of the measurements were administered at baseline and 3 months follow-up. Thirty-seven participants (MIND group = 22 and control group = 15) completed the study. The results found in the MIND diet group working memory + 1.37 (95% CI 0.79, 1.95), verbal recognition memory + 4.85 (95% CI 3.30, 6.40), and attention + 3.75 (95% CI 2.43, 5.07) improved more compared with the control group (ps < 0.05). Results of brain MRI consist of an increase in surface area of the inferior frontal gyrus in the MIND diet group. Furthermore, the results showed a decrease in the cerebellum-white matter and cerebellum-cortex in two groups of study. Still, the effect in the MIND group was greater than the control group. The study findings declare for the first time that the MIND diet intervention can reverse the destructive effects of obesity on cognition and brain structure, which could be strengthened by a modest calorie restriction.

Clinical trial registration ClinicalTrials.gov ID: NCT04383704 (First registration date: 05/05/2020).

High sucrose diet does not impact spatial cognition in rats using advanced touchscreen technology

INTRODUCTION

Western diets, including those consisting of saturated fats, simple sugars and processed foods, is rising at an unprecedented rate. These lead to obesity and metabolic diseases, and possibly cognitive deficits. Exploring this, recent studies demonstrate marked impairment in spatial learning in rodents exposed to high-sugar diets. We utilised advanced touchscreen technology to assess several spatial and non-spatial components of cognition in rats chronically exposed to a high sucrose diet.

METHODS

Male Wistar rats received 70 ml of 10% sucrose solution each day, or control tap water, persisting for the experiment duration (total n = 32). After 5 weeks of diet, rats performed Pairwise Discrimination, Location Discrimination, or Progressive Ratio tasks on automated touchscreens, and performance compared between groups.

RESULTS

Sucrose rats consumed all the sugar solution provided to them, and had significantly increased caloric intake, compared to controls (p < 0.0001). However, in all tests, we found no significant difference in cognitive performance between Sucrose and Control treated rats. This included the number of trials for acquisition, and reversal, in Pairwise Discrimination, and number of trials required to complete Location Discrimination (p > 0.05 for all outcomes). No differences were observed in perseverative behaviour, motivation levels, or processing speed.

CONCLUSION

Our study found no evidence to suggest that chronic consumption of sucrose impairs cognition, including both spatial and non-spatial learning tasks. These findings suggest that not all aspects of spatial cognition are negatively impacted by high sugar diet in rodents, and that particular use of touchscreen technology may probe different aspects of cognition than traditional tasks.

A meal enriched in saturated fat acutely impairs cognitive performance in obese men

BACKGROUND

Diets chronically high in saturated fat (SFA) associate with obesity and insulin resistance (IR), which in turn associate with cognitive decline and dementia. However, understanding how acute SFA consumption influences cognition is less clear despite short-term SFA-enriched diets inducing whole-body IR. We examined how consuming meals enriched with SFA or monounsaturated fat (MUFA) acutely influence cognitive function in lean and obese men. We hypothesized that greater diet-induced IR following a SFA-enriched meal would associate with decreased cognitive performance.

METHODS

Twelve lean and 12 obese males ingested meals containing no fat (CTL), enriched with SFA, or enriched with MUFA in a single-blind, randomized fashion. Cognitive testing and blood sampling were performed pre- and 2 h post-meal. Oral glucose tolerance (OGTT) and body composition were also assessed.

RESULTS

At baseline, fasting glucose, insulin, HOMA-IR, triglyceride, IL-6, and 2-hr glucose during an OGTT were higher in obese men (p < 0.001), while executive function (Stroop Test and Trail Making Test B-A) and working memory (Digit Span Test) were lower in obese men (p < 0.05). In response to the CTL and MUFA-enriched, no differences in cognitive measures were observed in lean or obese subjects. Following a SFA-enriched meal, obese subjects scored worse during cognitive testing (Stroop Test, Trail Making Test B-A, and Digit Span Test) compared to pre-meal scores (p < 0.05). These impairments in cognitive testing scores following the SFA-enriched meal associated with increased HOMA-IR (p < 0.01) and decreased plasma IL-6 (p < 0.05). No changes in cognitive function were observed in lean subjects following a SFA-enriched meal.

CONCLUSIONS

These data demonstrate that cognitive performance of obese men acutely worsens following a high-SFA meal. Reductions in cognitive performance associated with increased IR, suggesting that diet-induced IR may acutely decrease cognitive function.

Memory and eating: A bidirectional relationship implicated in obesity

This paper reviews evidence demonstrating a bidirectional relationship between memory and eating in humans and rodents. In humans, amnesia is associated with impaired processing of hunger and satiety cues, disrupted memory of recent meals, and overconsumption. In healthy participants, meal-related memory limits subsequent ingestive behavior and obesity is associated with impaired memory and disturbances in the hippocampus. Evidence from rodents suggests that dorsal hippocampal neural activity contributes to the ability of meal-related memory to control future intake, that endocrine and neuropeptide systems act in the ventral hippocampus to provide cues regarding energy status and regulate learned aspects of eating, and that consumption of hypercaloric diets and obesity disrupt these processes. Collectively, this evidence indicates that diet-induced obesity may be caused and/or maintained, at least in part, by a vicious cycle wherein excess intake disrupts hippocampal functioning, which further increases intake. This perspective may advance our understanding of how the brain controls eating, the neural mechanisms that contribute to eating-related disorders, and identify how to treat diet-induced obesity.

A narrative review on the effects of a ketogenic diet on patients with Alzheimer's disease

Alzheimer's disease (AD) has been very difficult to prevent and cure using the medicine available today. However, there has been some hope with using a ketogenic diet (KD) to reduce the cognitive and quality of life decline experienced by patients with AD. In this review, the authors discuss the research done on the effect of a KD on AD to provide some potential avenues for future research and to determine a KD that can be best adopted by patients. The authors also go over the effects of KD's and low-carbohydrate diets (LCDs) on the cognitive function of healthy patients and on patients without AD to determine the similar and dissimilar effects of the diets. The authors found that the KD was able to improve the cognitive abilities and quality of life of patients ranging from mild to severe AD. Several types of memory were improved as a result of the diets. Further research needs to be conducted to determine the cause behind these improvements. However, the several studies that were done were mostly in agreement that once ketosis was reached, cognitive improvements were observed in patients ranging from mild to severe AD or mild to moderate cognitive impairment. Through the use of a KD, potential mechanisms can be found to reduce the cognitive decline of patients with AD, and potentially even prevent the damaging effects of cognitive decline from AD altogether.

Microglia Regulate Neuronal Circuits in Homeostatic and High-Fat Diet-Induced Inflammatory Conditions

Microglia are brain resident macrophages, which actively survey the surrounding microenvironment and promote tissue homeostasis under physiological conditions. During this process, microglia participate in synaptic remodeling, neurogenesis, elimination of unwanted neurons and cellular debris. The complex interplay between microglia and neurons drives the formation of functional neuronal connections and maintains an optimal neural network. However, activation of microglia induced by chronic inflammation increases synaptic phagocytosis and leads to neuronal impairment or death. Microglial dysfunction is implicated in almost all brain diseases and leads to long-lasting functional deficiency, such as hippocampus-related cognitive decline and hypothalamus-associated energy imbalance (i.e., obesity). High-fat diet (HFD) consumption triggers mediobasal hypothalamic microglial activation and inflammation. Moreover, HFD-induced inflammation results in cognitive deficits by triggering hippocampal microglial activation. Here, we have summarized the current knowledge of microglial characteristics and biological functions and also reviewed the molecular mechanism of microglia in shaping neural circuitries mainly related to cognition and energy balance in homeostatic and diet-induced inflammatory conditions.

Short-term high-fat diet favors the appearances of apoptosis and gliosis by activation of ERK1/2/p38MAPK pathways in brain

High-fat diet (HFD) has been associated with neuroinflammation and apoptosis in distinct brain regions. To explore the effect of short-term (7, 14 and 21 days) high-fat overfeeding on apoptosis, inflammatory signaling proteins, APP changes and glial cell activities in cerebral cortex and cerebellum. Mice were fed with HFD for different lengths (up to 21 days) and after each time body weights of mice was tested, then the apoptotic proteins, IL-1β, APP, BACE1and MAPKs, Akt and NF-κB signaling activity were evaluated by western blots. Results demonstrate that short period of high-fat overnutrition significantly promotes apoptosis, APP expression at day 21 of cerebral cortex and at day 7 of cerebellum compared to chow diet. In addition, increased GFAP+astrocytes, Iba-1+microglia and IL-1β 30 were observed in cerebral cortex after 21 days HFD, but no changes for 7 days overfeeding of cerebellum. Serendipitously, ERK1/2 pathway was activated both in cerebral cortex and cerebellum for different time course of HFD. Furthermore, increased phospho-p38 MAPK level was observed in cerebellum only. In consistent with in vivo results, SH-SY5Y cells treatment with cholesterol (50 μM, 100 μM) for 48 h culture in vitro demonstrated that pro-apoptotic proteins were enhanced as well. In brief, short-term HFD consumption increases sensitivity to apoptosis, APP and IL-1β production as well as gliosis in cerebral cortex and cerebellum, which may be related to enhancement of ERK1/2 and p38 MAPK activation.

Crème de la Créature: Dietary Influences on Behavior in Animal Models

In humans, alterations in cognitive, motivated, and affective behaviors have been described with consumption of processed diets high in refined sugars and saturated fats and with high body mass index, but the causes, mechanisms, and consequences of these changes remain poorly understood. Animal models have provided an opportunity to answer these questions and illuminate the ways in which diet composition, especially high-levels of added sugar and saturated fats, contribute to brain physiology, plasticity, and behavior. Here we review findings from invertebrate (flies) and vertebrate models (rodents, zebrafish) that implicate these diets with changes in multiple behaviors, including eating, learning and memory, and motivation, and discuss limitations, open questions, and future opportunities.

Circadian Clock Regulates Inflammation and the Development of Neurodegeneration

The circadian clock regulates numerous key physiological processes and maintains cellular, tissue, and systemic homeostasis. Disruption of circadian clock machinery influences key activities involved in immune response and brain function. Moreover, Immune activation has been closely linked to neurodegeneration. Here, we review the molecular clock machinery and the diurnal variation of immune activity. We summarize the circadian control of immunity in both central and peripheral immune cells, as well as the circadian regulation of brain cells that are implicated in neurodegeneration. We explore the important role of systemic inflammation on neurodegeneration. The circadian clock modulates cellular metabolism, which could be a mechanism underlying circadian control. We also discuss the circadian interventions implicated in inflammation and neurodegeneration. Targeting circadian clocks could be a potential strategy for the prevention and treatment of inflammation and neurodegenerative diseases.

Unravelling the impacts of western-style diets on brain, gut microbiota and cognition

The steady rise in the prevalence of obesity has been fostered by modern environments that reduce energy expenditure and encourage consumption of 'western'-style diets high in fat and sugar. Obesity has been consistently associated with impairments in executive function and episodic memory, while emerging evidence indicates that high-fat, high-sugar diets can impair aspects of cognition within days, even when provided intermittently. Here we review the detrimental effects of diet and obesity on cognition and the role of inflammatory and circulating factors, compromised blood-brain barrier integrity and gut microbiome changes. We next evaluate evidence for changing risk profiles across life stages (adolescence and ageing) and other populations at risk (e.g. through maternal obesity). Finally, interventions to ameliorate diet-induced cognitive deficits are discussed, including dietary shifts, exercise, and the emerging field of microbiome-targeted therapies. With evidence that poor diet and obesity impair cognition via multiple mechanisms across the human lifespan, the challenge for future research is to identify effective interventions, in addition to diet and exercise, to prevent and ameliorate adverse effects.

Clusterin overexpression as a potential neuroprotective response to the pathological effects of high fat dieting on the brain reward system

High-fat diets (HFDs) can lead to pathological changes in the brain underlying several behavioral disturbances (e.g., reward deficiency). To further increase our knowledge of these associations, we studied the sucrose reward and the brain expression of clusterin, a protein that is overexpressed after several kind of brain damaging conditions. C57BL/6J male mice were differentially fed on an HFD or standard chow for 41 days and underwent 11 sucrose place conditioning sessions followed by 4 extinction sessions to monitor the effects of HFD on sucrose reward by means of free choice tests. We quantified clusterin expression by immunochemistry in the nucleus accumbens, dorsal striatum and cingulate cortex. HFD tended to provoke a transient potentiation in the acquisition of sucrose-conditioned place preference, but this effect was followed by a much more consistent reduction in sucrose preference, which spontaneously disappeared after 31 days of an HFD with no need for extinction learning. The HFD mice showed higher clusterin expression in the nucleus accumbens but not in the other brain areas studied. The results confirm that HFDs strongly influence the rewarding properties of palatable foods and suggest a direct connection with neurotoxic alterations in the brain reward system tagged by clusterin overexpression.

The impact of dietary macronutrient intake on cognitive function and the brain

Macronutrients - carbohydrates, fats, and proteins - supply the nutrients required for optimal functioning. Inadequate intake compromises both physical and brain health. We synthesized research on macronutrients from whole meals on cognitive function in healthy adults and identified underlying mechanisms. Intake of simple carbohydrates ('sugars') is consistently associated with decreased global cognition whereas consumption of complex carbohydrates correlates with successful brain aging and improved memory both in the short- and long-term. Saturated fatty acid intake correlates with decreased memory and learning scores whereas omega-3 intake correlates positively with memory scores. Protein intake boosts executive function and working memory when task-demands are high. Individual differences affecting the macronutrient-cognition relationship are age, physical activity, and glucose metabolism. Neural correlates reflect findings on cognitive functions: cortical thickness and cerebral amyloid burden correlate with sugar intake, inflammatory status and cerebral glucose metabolism correlate with fatty acid intake. Key mechanisms by which dietary macronutrients affect the brain and cognition include glucose and insulin metabolism, neurotransmitter actions, and cerebral oxidation and inflammation. In conclusion, macronutrient intake affects cognitive function both acutely and in the long-term, involving peripheral and central mechanisms. A healthy diet supports brain integrity and functionality, whereas inadequate nutrition compromises it. Studying diet can be key to nutritional recommendations, thereby improving the landscape of mental health and healthy brain aging.

Cardiac magnetic resonance imaging: insights into developmental programming and its consequences for aging

Cardiovascular diseases (CVD) are important consequences of adverse perinatal conditions such as fetal hypoxia and maternal malnutrition. Cardiac magnetic resonance imaging (CMR) can produce a wealth of physiological information related to the development of the heart. This review outlines the current state of CMR technologies and describes the physiological biomarkers that can be measured. These phenotypes include impaired ventricular and atrial function, maladaptive ventricular remodeling, and the proliferation of myocardial steatosis and fibrosis. The discussion outlines the applications of CMR to understanding the developmental pathways leading to impaired cardiac function. The use of CMR, both in animal models of developmental programming and in human studies, is described. Specific examples are given in a baboon model of intrauterine growth restriction (IUGR). CMR offers great potential as a tool for understanding the sequence of dysfunctional adaptations of developmental origin that can affect the human cardiovascular system.

3-Hydroxybutyrate as a Metabolite and a Signal Molecule Regulating Processes of Living Organisms

3-hydroxybutyrate (3-HB) as a very important metabolite occurs in animals, bacteria and plants. It is well known that in animals, 3-HB is formed as a product of the normal metabolism of fatty acid oxidation and can therefore be used as an energy source in the absence of sufficient blood glucose. In microorganisms, 3-HB mainly serves as a substrate for the synthesis of polyhydroxybutyrate, which is a reserve material. Recent studies show that in plants, 3-HB acts as a regulatory molecule that most likely influences the expression of genes involved in DNA methylation, thereby altering DNA methylation levels. Additionally, in animals, 3-HB is not only an intermediate metabolite, but also an important regulatory molecule that can influence gene expression, lipid metabolism, neuronal function, and overall metabolic rate. Some of these effects are the direct effects of 3-HB itself, while others are indirect effects, regulated by the metabolites into which 3-HB is converted. One of the most important regulatory functions of 3-HB is the inhibition of the activity of histone deacetylases and thus the epigenetic regulation of many genes. Due to the number of functions of this compound, it also shows promising therapeutic properties.

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.

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.

The Effect of Short-Term Feeding of a High-Coconut Oil or High-Fat Diet on Neuroinflammation and the Performance of an Object-Place Task in Rats

The consumption of high-fat and high-sugar diets, in the form of junk food, and binge eating are now common. Increasing evidence suggests that a high-fat diet (HFD) can induce neuroinflammation and alter behavior. I aimed to study the effects of diets of differing fat content on neuroinflammation and spatial memory using an object-place (OP) task. Thirty-two adult male rats were allocated to four groups and fed a regular diet (Regular diet), a control diet (Control diet), an HFD (60% of calories from lard), or a high-coconut oil diet (HCOD; 60% of calories from coconut oil) for 3 days. Their water intake, food consumption, body mass, and metabolic variables were measured. HFD-fed rats showed significantly poorer performance on the OP task, as assessed using the discrimination index (- 0.208 ± 0.094), than the Regular (0.462 ± 0.078; P < 0.0001) and Control (0.379 ± 0.081; P = 0.0003) groups. However, no significant difference was observed in spatial memory between the HCOD and Regular groups. The concentrations of neuroinflammatory markers (interleukin [IL]-1β, IL-6, tumor necrosis factor α, and nuclear factor κB) were also measured in the hippocampus and prefrontal cortex. HFD-fed rats showed significantly higher levels of neuroinflammatory markers than the Regular and Control diet-fed groups. HCOD feeding did not induce neuroinflammation in the hippocampus and prefrontal cortex compared with the Regular and Control groups.

Integrative Analyses of mRNA Expression Profile Reveal SOCS2 and CISH Play Important Roles in GHR Mutation-Induced Excessive Abdominal Fat Deposition in the Sex-Linked Dwarf Chicken

Sex-linked dwarf (SLD) chicken, which is caused by a recessive mutation of the growth hormone receptor (GHR), has been widely used in the Chinese broiler industry. However, it has been found that the SLD chicken has more abdominal fat deposition than normal chicken. Excessive fat deposition not only reduced the carcass quality of the broilers but also reduced the immunity of broilers to diseases. To find out the key genes and the precise regulatory pathways that were involved in the GHR mutation-induced excessive fat deposition, we used high-fat diet (HFD) and normal diet to feed the SLD chicken and normal chicken and analyzed the differentially expressed genes (DEGs) among the four groups. Results showed that the SLD chicken had more abdominal fat deposition and larger adipocytes size than normal chicken and HFD can promote abdominal fat deposition and induce adipocyte hypertrophy. RNA sequencing results of the livers and abdominal fats from the above chickens revealed that many DEGs between the SLD and normal chickens were enriched in fat metabolic pathways, such as peroxisome proliferator-activated receptor (PPAR) signaling, extracellular matrix (ECM)-receptor pathway, and fatty acid metabolism. Importantly, by constructing and analyzing the GHR-downstream regulatory network, we found that suppressor of cytokine signaling 2 (SOCS2) and cytokine-inducible SH2-containing protein (CISH) may involve in the GHR mutation-induced abdominal fat deposition in chicken. The ectopic expression of SOCS2 and CISH in liver-related cell line leghorn strain M chicken hepatoma (LMH) cell and immortalized chicken preadipocytes (ICP) revealed that these two genes can regulate fatty acid metabolism, adipocyte differentiation, and lipid droplet accumulation. Notably, overexpression of SOCS2 and CISH can rescue the hyperactive lipid metabolism and excessive lipid droplet accumulation of primary liver cell and preadipocytes that were isolated from the SLD chicken. This study found some genes and pathways involved in abdominal fat deposition of the SLD chicken and reveals that SOCS2 and CISH are two key genes involved in the GHR mutation-induced excessive fat deposition of the SLD chicken.