Early and sustained exposure to high-sucrose diet triggers hippocampal ER stress in young rats

Limosilactobacillus reuteri DSM 17938 relieves inflammation, endoplasmic reticulum stress, and autophagy in hippocampus of western diet-fed rats by modulation of systemic inflammation

The consumption of western diets, high in fats and sugars, is a crucial contributor to brain molecular alterations, cognitive dysfunction and neurodegenerative diseases. Therefore, a mandatory challenge is the individuation of strategies capable of preventing diet-induced impairment of brain physiology. A promising strategy might consist in the administration of probiotics that are known to influence brain function via the gut-brain axis. In this study, we explored whether Limosilactobacillus reuteri DSM 17938 (L. reuteri)-based approach can counteract diet-induced neuroinflammation, endoplasmic reticulum stress (ERS), and autophagy in hippocampus, an area involved in learning and memory, in rat fed a high fat and fructose diet. The western diet induced a microbiota reshaping, but L. reuteri neither modulated this change, nor the plasma levels of short-chain fatty acids. Interestingly, pro-inflammatory signaling pathway activation (increased NFkB phosphorylation, raised amounts of toll-like receptor-4, tumor necrosis factor-alpha, interleukin-6, GFAP, and Haptoglobin), as well as activation of ERS (increased PERK and eif2α phosphorylation, higher C/EBP-homologous protein amounts) and autophagy (increased beclin, P62-sequestosome-1, and LC3 II) was revealed in hippocampus of western diet fed rats. All these hippocampal alterations were prevented by L. reuteri administration, showing for the first time a neuroprotective role of this specific probiotic strain, mainly attributable to its ability to regulate western diet-induced metabolic endotoxemia and systemic inflammation, as decreased levels of lipopolysaccharide, plasma cytokines, and adipokines were also found. Therapeutic strategies based on the use of L. reuteri DSM17938 could be beneficial in reversing metabolic syndrome-mediated brain dysfunction and cognitive decline.

Diabetes and Cognitive Decline: An Innovative Approach to Analyzing the Biophysical and Vibrational Properties of the Hippocampus

Diabetes Mellitus (DM) is a disease characterized by high blood glucose levels, known as hyperglycemia. Diabetes represents a risk factor for the development of neurodegenerative diseases, such as Alzheimer's Disease (AD), one of the most prevalent neurodegenerative diseases worldwide, which leads to progressive mental, behavioral, and functional decline, affecting many brain structures, especially the hippocampus. Here, we aim to characterize the ultrastructural, nanomechanical, and vibrational changes in hyperglycemic hippocampal tissue using atomic force microscopy (AFM) and Raman spectroscopy. DM was induced in rats by streptozotocin injection (type 1) or dietary intervention (type 2). Cryosections of the hippocampus were prepared and analyzed on an MM8 AFM (Bruker) in Peak Force Quantitative Nanomechanics mode, performing 25 μm2 scans in 9 regions of 3 samples from each group. Ultrastructural and nanomechanical data such as surface roughness, area, volume, Young's modulus, and adhesion were evaluated. The hippocampal samples were also analyzed on a T64000 Spectrometer (Horiba), using a laser λ = 632.8 nm, and for each sample, four spectra were obtained in different regions. AFM analyses show changes on the ultrastructural scale since diabetic animals had hippocampal tissue with greater roughness and volume. Meanwhile, diabetic tissues had decreased adhesion and Young's modulus compared to control tissues. These were corroboratedby Raman data that shows changes in the molecular composition of diabetic tissues. The individual spectra show that the most significant changes are in the amide, cholesterol, and lipid bands. Overall, the data presented here show that hyperglycemia induces biophysical alterations in the hippocampal tissue of diabetic rats, providing novel biophysical and vibrational cues on the relationship between hyperglycemia and dementia.

Recovery Sleep Immediately after Prolonged Sleep Deprivation Stimulates the Transcription of Integrated Stress Response-Related Genes in the Liver of Male Rats

Sleep loss induces performance impairment and fatigue. The reactivation of human herpesvirus-6, which is related to the phosphorylation of eukaryotic translation initiation factor 2α (eIF2α), is one candidate for use as an objective biomarker of fatigue. Phosphorylated eIF2α is a key regulator in integrated stress response (ISR), an intracellular stress response system. However, the relation between sleep/sleep loss and ISR is unclear. The purpose of the current study was to evaluate the effect of prolonged sleep deprivation and recovery sleep on ISR-related gene expression in rat liver. Eight-week-old male Sprague-Dawley rats were subjected to a 96-hour sleep deprivation using a flowerpot technique. The rats were sacrificed, and the liver was collected immediately or 6 or 72 h after the end of the sleep deprivation. RT-qPCR was used to analyze the expression levels of ISR-related gene transcripts in the rat liver. The transcript levels of the Atf3, Ddit3, Hmox-1, and Ppp15a1r genes were markedly increased early in the recovery sleep period after the termination of sleep deprivation. These results indicate that both activation and inactivation of ISRs in the rat liver occur simultaneously in the early phase of recovery sleep.

A high sucrose diet modifies brain oxylipins in a sex-dependent manner

BACKGROUND

Oxylipins have been implicated in many biological processes and diseases. Dysregulation of cerebral lipid homeostasis and altered lipid metabolites have been associated with the onset and progression of dementia. Although most dietary interventions have focused on modulation of dietary fats, the impact of a high sucrose diet on the brain oxylipin profile is unknown.

METHODS

Male and female C57BL/6J mice were fed a high sucrose diet (HSD, 34%) in comparison to a control low sucrose diet (LSD, 12%) for 12 weeks beginning at 20 weeks of age. The profile of 53 free oxylipins was then measured in brain by ultra-high performance liquid chromatography tandem mass spectrometry. Serum glucose and insulin were measured enzymatically. We first assessed whether there were any effects of the diet on the brain oxylipin profile, then assessed for sex differences.

RESULTS

There were no differences in fasting serum glucose between the sexes for mice fed a HSD or in fasting serum insulin levels for mice on either diet. The HSD altered the brain oxylipin profile in both sexes in distinctly different patterns: there was a reduction in three oxylipins (by 47-61%) and an increase in one oxylipin (16%) all downstream of lipoxygenase enzymes in males and a reduction in eight oxylipins (by 14-94%) mostly downstream of cyclooxygenase activity in females. 9-oxo-ODE and 6-trans-LTB4 were most influential in the separation of the oxylipin profiles by diet in male mice, whereas 5-HEPE and 12-HEPE were most influential in the separation by diet in female mice. Oxylipins 9‑hydroxy-eicosatetraenoic acid (HETE), 11-HETE, and 15-HETE were higher in the brains of females, regardless of diet.

CONCLUSION

A HSD substantially changes brain oxylipins in a distinctly sexually dimorphic manner. Results are discussed in terms of potential mechanisms and links to metabolic disease. Sex and diet effects on brain oxylipin composition may provide future targets for the management of neuroinflammatory diseases, such as dementia.

High Glycemia and Soluble Epoxide Hydrolase in Females: Differential Multiomics in Murine Brain Microvasculature

The effect of a high glycemic diet (HGD) on brain microvasculature is a crucial, yet understudied research topic, especially in females. This study aimed to determine the transcriptomic changes in female brain hippocampal microvasculature induced by a HGD and characterize the response to a soluble epoxide hydrolase inhibitor (sEHI) as a mechanism for increased epoxyeicosatrienoic acids (EETs) levels shown to be protective in prior models of brain injury. We fed mice a HGD or a low glycemic diet (LGD), with/without the sEHI (t-AUCB), for 12 weeks. Using microarray, we assessed differentially expressed protein-coding and noncoding genes, functional pathways, and transcription factors from laser-captured hippocampal microvessels. We demonstrated for the first time in females that the HGD had an opposite gene expression profile compared to the LGD and differentially expressed 506 genes, primarily downregulated, with functions related to cell signaling, cell adhesion, cellular metabolism, and neurodegenerative diseases. The sEHI modified the transcriptome of female mice consuming the LGD more than the HGD by modulating genes involved in metabolic pathways that synthesize neuroprotective EETs and associated with a higher EETs/dihydroxyeicosatrienoic acids (DHETs) ratio. Our findings have implications for sEHIs as promising therapeutic targets for the microvascular dysfunction that accompanies vascular dementia.

Melatonin attenuates spatial learning and memory dysfunction in developing rats by suppressing isoflurane-induced endoplasmic reticulum stress via the SIRT1/Mfn2/PERK signaling pathway

Use of the inhalation anesthetic isoflurane may increase the risk of cognitive deficiency and neurotoxicity after birth. A growing body of evidence suggests that melatonin is an effective treatment for various types of oxidative stress damage and neurodegenerative disease. In this study, we aimed to examine the effects of melatonin on isoflurane-induced endoplasmic reticulum (ER) stress, spatial learning and memory impairment during development. The rats were grouped according to whether the rats were exposed to isoflurane or a control gas and whether they were administered melatonin or phosphate buffered saline (PBS). We administered isoflurane to 7-day-old Sprague-Dawley rat pups with intraperitoneal injections of melatonin (20 mg/kg) 15 min before and 3 h after the initiation of anesthesia. Twelve hours after isoflurane anesthesia, rats were randomly selected from each group and sacrificed. The hippocampal tissue and serum were collected to determine the levels of SIRT1, Mfn2, PERK, and other proteins or cytokines related to ER stress, apoptosis, and neuroinflammation. Subsequently, all remaining rats were assessed for spatial learning and memory deficiency 31 days after birth using the Morris water maze test. We found that melatonin attenuated isoflurane-induced ER stress and neuroapoptosis in the hippocampus and decreased the level of neuroinflammatory markers in the serum of newborn rats, resulting in improved spatial learning and memory. In addition, the neuroprotective effect of melatonin was weakened after the SIRT1/Mfn2/PERK signaling pathway was suppressed by lentivirus transfection. Therefore, our findings demonstrate that melatonin ameliorates spatial learning and memory impairment after isoflurane exposure, and these beneficial effects are associated with a reduction in ER stress, neuroapoptosis, and neuroinflammation via the SIRT1/Mfn2/PERK signaling pathway.

Hippocampal Endoplasmic Reticulum Stress Hastens Motor and Cognitive Decline in Adult Male Rats Sustainedly Exposed to High-Sucrose Diet

Metabolic dysfunctions, such as hyperglycemia and insulin resistance, have been associated to cognitive impairment and dementia regardless of advanced age, although the underlying mechanisms are still elusive. Thus, this study investigates the deleterious effects of metabolic syndrome (MetS) induced by long-term exposure to a high-sucrose diet on motor and cognitive functions of male adult rats and its relationship with hippocampal endoplasmic reticulum (ER) stress. Weaned Wistar male rats were fed a high-sucrose diet until adulthood (HSD; 6 months old) and compared to both age-matched (CTR; 6 months old) and middle-aged chow-fed rats (OLD; 20 months old). MetS development, serum redox profile, behavioral, motor, and cognitive functions, and hippocampal gene/protein expressions for ER stress pro-adaptive and pro-apoptotic pathways, as well as senescence markers were assessed. Prolonged exposure to HSD induced MetS hallmarked by body weight gain associated to central obesity, hypertriglyceridemia, insulin resistance, and oxidative stress. Furthermore, HSD rats showed motor and cognitive decline similar to that in OLD animals. Noteworthy, HSD rats presented marked hippocampal ER stress characterized by failure of pro-adaptive signaling and increased expression of Chop, p21, and Parp-1 cleavage, markers of cell death and aging. This panorama resembles that found in OLD rats. In toto, our data showed that early and sustained exposure to a high-sucrose diet induced MetS, which subsequently led to hippocampus homeostasis disruption and premature impairment of motor and cognitive functions in adult rats.

Early Adversity and Accelerated Brain Aging: A Mini-Review

Early adversity is an important risk factor that influences brain aging. Diverse animal models of early adversity, including gestational stress and postnatal paradigms disrupting dam-pup interactions evoke not only persistent neuroendocrine dysfunction and anxio-depressive behaviors, but also perturb the trajectory of healthy brain aging. The process of brain aging is thought to involve hallmark features such as mitochondrial dysfunction and oxidative stress, evoking impairments in neuronal bioenergetics. Furthermore, brain aging is associated with disrupted proteostasis, progressively defective epigenetic and DNA repair mechanisms, the build-up of neuroinflammatory states, thus cumulatively driving cellular senescence, neuronal and cognitive decline. Early adversity is hypothesized to evoke an “allostatic load” via an influence on several of the key physiological processes that define the trajectory of healthy brain aging. In this review we discuss the evidence that animal models of early adversity impinge on fundamental mechanisms of brain aging, setting up a substratum that can accelerate and compromise the time-line and nature of brain aging, and increase risk for aging-associated neuropathologies.

Inhibition of Soluble Epoxide Hydrolase Is Protective against the Multiomic Effects of a High Glycemic Diet on Brain Microvascular Inflammation and Cognitive Dysfunction

Diet is a modifiable risk factor for cardiovascular disease (CVD) and dementia, yet relatively little is known about the effect of a high glycemic diet (HGD) on the brain’s microvasculature. The objective of our study was to determine the molecular effects of an HGD on hippocampal microvessels and cognitive function and determine if a soluble epoxide hydrolase (sEH) inhibitor (sEHI), known to be vasculoprotective and anti-inflammatory, modulates these effects. Wild type male mice were fed a low glycemic diet (LGD, 12% sucrose/weight) or an HGD (34% sucrose/weight) with/without the sEHI, trans-4-[4-(3-adamantan-1-yl-ureido)-cyclohexyloxy]-benzoic acid (t-AUCB), for 12 weeks. Brain hippocampal microvascular gene expression was assessed by microarray and data analyzed using a multi-omic approach for differential expression of protein and non-protein-coding genes, gene networks, functional pathways, and transcription factors. Global hippocampal microvascular gene expression was fundamentally different for mice fed the HGD vs. the LGD. The HGD response was characterized by differential expression of 608 genes involved in cell signaling, neurodegeneration, metabolism, and cell adhesion/inflammation/oxidation effects reversible by t-AUCB and hence sEH inhibitor correlated with protection against Alzheimer’s dementia. Ours is the first study to demonstrate that high dietary glycemia contributes to brain hippocampal microvascular inflammation through sEH.

Evaluation of the Effects of Different Dietary Patterns on Breast Cancer: Monitoring Circulating Tumor Cells

The occurrence and development of breast cancer are closely related to dietary factors, especially dietary patterns. This study was to investigate the effects of dietary patterns on the process of tumor metastasis by in vivo circulating tumor cell (CTC) capture strategy and monitoring changes of CTC numbers in breast tumor mice model. Meanwhile, the effects of different dietary patterns on the development of lung metastases of breast cancer and the volume and weight of carcinoma in situ were investigated. In this study, the increase in the number of CTCs was significantly promoted by dietary patterns such as high-salt diet, high-sugar diet, and high-fat diet, while it was delayed by ketogenic diet, low-fat diet, low-protein diet, diet restriction, and Mediterranean diet. These results indicated that the in vivo capture and detection of CTCs provides a convenient method for real-time cancer metastasis monitoring, and through in-depth study of the effects of different dietary patterns on tumor growth and metastasis, it can expand a new horizon in future cancer treatments.

Evaluation of sucrose-enriched diet consumption in the development of risk factors associated to type 2 diabetes, atherosclerosis and non-alcoholic fatty liver disease in a murine model

Overconsumption of sucrose, the main contributor of the total added sugar intake in the world, has been associated with negative metabolic effects related to non-communicable diseases. However, this relationship continues to be a controversial topic and further studies are needed. The aim of this study was to evaluate the sucrose-enriched diet consumption in the development of risk factors associated with type 2 diabetes, atherosclerosis and non-alcoholic fatty liver disease in a murine model. Sucrose-enriched diet-fed rats showed a decrease in food, lipids and protein intake as well as in serum total cholesterol levels, an increase in carbohydrates intake, glucose, insulin, triglycerides, VLDL-c and HDL-c levels and a greater degree of insulin resistance, steatosis and non-alcoholic steatohepatitis. Our results show that sucrose-enriched diet consumption during 25 weeks contribute to the development of risk factors associated with type 2 diabetes, atherosclerosis and non-alcoholic fatty liver disease in male Wistar rats.

Motor learning impairment in rats under a high sucrose diet

Motor learning skills are reliable indicators of behavioral acquisition and cognitive disorders. The ease with which learning skills are measured disparities the complexity of the interpretation concerning neural plasticity. Conversely, a wealth of information regarding metabolic derangements has long been reported with direct connection to high sucrose diets. However, the impact of excessive sucrose consumption on undergoing cognitive processes has been only scarcely addressed up to now. Therefore, the goal of this work was to describe the associative relationship between high sucrose consumption and changes in motor learning skills acquisition. Motor learning impairments conditioned by central alterations are hypothesized. Rotarod, elevated plus-maze and open field trials, along with metabolic and pro-inflammatory biomarkers tests in Wistar rats under a high sucrose treatment, were performed. Motor learning impairment in high sucrose diet-treated rats was found while spontaneous locomotor activity remained unchanged. Even though, no anxiety-like behavior under high sucrose diet-treatment was observed. Consistently, the worst outcome in the glucose tolerance test was developed, the worst motor learning performance was observed. Furthermore, insulin resistance correlated positively with a pro-inflammatory state and a decreased latency to fall in the rotarod test. Indeed, C-reactive protein and tumor necrosis factor-α serum levels, along with the homeostasis model assessment of insulin resistance (HOMA-IR), significantly increased in motor learning impairment. Together, these results support behavioral, metabolic and pro-inflammatory changes associated with deleterious changes in central nervous system likely involving crucial motor learning structures. Underlying pro-inflammatory-triggered processes may explain cognitive disorders in advanced states of metabolic derangements.

Early Exposure to High-Sucrose Diet Leads to Deteriorated Ovarian Health

BACKGROUND

The metabolic syndrome (MetS) is correlated with disorders of the reproductive system, such as the polycystic ovary syndrome (PCOS). While consumption of a diet rich in carbohydrates is linked to the development of MetS, it is still unclear if this diet leads to ovarian dysfunction and PCOS.

OBJECTIVES

We investigated the influence of a high-sucrose diet (HSD) on the ovarian milieu of Wistar rats and studied the correlation between high consumption of sugary drinks and the prevalence of PCOS in women.

METHODS

Wistar rats were given a standard laboratory diet (CTR, 10% sucrose, n = 8) or HSD (HSD, 25% sucrose, n = 8) from postnatal day 21 to 120. Animals were evaluated weekly to calculate food intake, feed efficiency and weight gain. Both onset of puberty and estrous cycle were monitored. Metabolic serum biochemistry, organ morphometry and ovarian histology were performed upon euthanasia. In parallel, a fixed-effects multiple linear regression analysis was performed using data from Brazilian states (459 state-year observations) to test the correlation between the consumption of sugar-sweetened beverages (surrogate for HSD intake) and the prevalence of PCOS (surrogate for ovarian dysfunction).

RESULTS

HSD animals showed increased adipose tissue accumulation, hyperglycaemia and insulin resistance when compared to CTR. Interestingly HSD rats also entered puberty earlier than CTR. Moreover, ovaries from HSD animals had an increased number of atretic antral follicles and cystic follicles, which were correlated with the hypertrophy of periovarian adipocytes. Finally, there was a positive correlation between the intake of sugary drinks and prevalence of PCOS in women of reproductive age.

CONCLUSIONS

HSD ingestion leads to ovarian dysfunction in rats and could be correlated with PCOS in women, suggesting these alterations could lead to public health issues. Therefore, we reinforce the deleterious impact of HSD to the ovarian system and suggest that the reduction of added sugars intake could be beneficial to ovarian health.

High-sugar diet intake, physical activity, and gut microbiota crosstalk: Implications for obesity in rats

This study aims to evaluate the effect of long-term high-sugar diet (HSD) intake and regular physical activity on gut microbiota as well as its health impact. Weaned male Wistar rats were fed with standard chow diet (SSD) or HSD ad libitum and subjected or not to regular swimming training with a workload (2% of body weight) for 15 weeks. Feces samples were used on microbiome analysis using 16S rRNA amplicon sequencing. HSD increased body mass, adipose cushions, and the serum levels of triglycerides and VLDL, also changed the bacteria taxons associated with metabolic disorders (increase taxons belonging to Proteobacteria phylum and decrease Pediococcus genus); the swim training reverted these changes. SSD intake increased the abundance of bacteria associated with metabolization of dietary fiber. Training in association with SSD consumption beneficially modulated the microbiota, increasing the Bacteroidetes, Bacteroidaceae, Porphyromonadaceae, Parabacteroides, and Lactobacillaceae, and decreasing the Firmicute/Bacteroidetes ratio; training was not able to maintain this profile in animals SHD-fed. Physical training modulates the gut microbiota reversing the obesogenic response caused by SHD. However, training itself is not efficient for up-regulating the probiotic bacteria in comparison to its association with a balanced diet.

The impact of chronic stress on energy metabolism

The brain is exceptionally demanding in terms of energy metabolism. Approximately 20% of the calories consumed are devoted to our cerebral faculties, with the lion's share provided in the form of glucose. The brain's stringent energy dependency requires a high degree of harmonization between the elements responsible for supplying- and metabolizing energetic substrates. However, chronic stress may jeopardize this homeostatic energy balance by disruption of critical metabolic processes. In agreement, stress-related mental disorders have been linked with perturbations in energy metabolism. Prominent stress-induced metabolic alterations include the actions of hormones, glucose uptake and mitochondrial adjustments. Importantly, fundamental stress-responsive metabolic adjustments in humans and animal models bear a striking resemblance. Here, an overview is provided of key findings, demonstrating the pervasive impact of chronic stress on energy metabolism. Furthermore, I argue that medications, aimed primarily at restoring metabolic homeostasis, may constitute a novel approach to treat mental disorders.

Post-weaning exposure to high-sucrose diet induces early non-alcoholic fatty liver disease onset and progression in male mice: role of dysfunctional white adipose tissue

Non-alcoholic fatty liver disease (NAFLD) is the hepatic manifestation of metabolic syndrome, ranging from simple steatosis to non-alcoholic steatohepatitis (NASH) particularly among chronic consumers of added sugar-rich diets. However, the impact of early consumption of such diets on NAFLD onset and progression is unclear. Thus, this study sought to characterise metabolic factors involved in NAFLD progression in young mice fed with a high-sucrose diet (HSD). Male Swiss mice were fed HSD or regular chow (CTR) from weaning for up to 60 or 90 days. Obesity development, glucose homeostasis and serum biochemical parameters were determined at each time-point. At day 90, mice were euthanised and white adipose tissue (WAT) collected for lipolytic function assessment and liver for histology, gene expression and cytokines quantification. At day 60, HSD mice presented increased body mass, hypertriglyceridemia, peripheral insulin resistance (IR) and simple steatosis. Upon 90 days on diet, WAT from HSD mice displayed impaired insulin sensitivity, which coincided with increased fasting levels of glucose and free fatty acids (FFA), as well as NAFLD progression to NASH. Transcriptional levels of lipogenic genes, particularly stearoyl-CoA desaturase-1, were consistently increased, leading to hepatic leukocyte infiltration and pro-inflammatory cytokines spillover. Therefore, our dataset supports IR triggering in the WAT as a major factor for dysfunctional release of FFA towards portal circulation and consequent upregulation of lipogenic genes and hepatic inflammatory onset, which decisively concurred for NAFLD-to-NASH progression in young HSD-fed mice. Notwithstanding, this study forewarns against the early introduction of dietary sugars in infant diet, particularly following breastfeeding cessation.

High-sugar diet leads to obesity and metabolic diseases in ad libitum -fed rats irrespective of caloric intake

Objective Provide a comprehensive view of the events surrounding the sugar consumption, under conditions of energy equivalence; through the analysis of behavioral aspects of intake, and of biochemical, metabolic and physiological parameters, as well as the effect of this nutrient on the plasticity of adipose tissue. Materials and methods Newly weaned male Wistar rats were classified in two groups and subjected to the following normocaloric diets: standard chow diet or to high-sugar diet (HSD) ad libitum for 18 weeks. Results The animals submitted to the HSD were associated with a lower caloric intake during the 18 weeks of experimentation. However, the HSD induced a significant increase in body weight, white adipose tissue weight, adiposity index, Lee index, and the levels of triglycerides and very low-density lipoprotein in the serum. In addition, it induced glucose intolerance, insulin resistance and compensatory increase of insulin secretion by pancreatic β-cells. Also increased heart rate and induced hyperplasia, and hypertrophy of retroperitoneal visceral adipose tissue. In the liver, the HSD was associated with increased hepatic lipid content (i.e., triglycerides and cholesterol) and hepatomegaly. Conclusion The post-weaning consumption of HSD induces an adaptive response in metabolism; however, such an event is not enough to reverse the homeostatic imbalance triggered by the chronic consumption of this macronutrient, leading to the development of metabolic syndrome, irrespective of caloric intake. These findings corroborate recent evidence indicating that sugar is a direct contributor to metabolic diseases independent of a positive energy balance. Arch Endocrinol Metab. 2020;64(1):71-81.

Effects of Vitamin C on the Prevention of Ischemia-Reperfusion Brain Injury: Experimental Study in Rats

Background

Reperfusion syndrome after carotid endarterectomy is a complication associated with cerebrovascular self-regulation in a chronically hypoperfused cerebral hemisphere, leading to severe neurological damage. Vitamin C is an important antioxidant in brain metabolism that has shown some neuroprotective actions.

Objective

To investigate the potential effects of vitamin C on cerebral reperfusion in comparison with placebo (saline) in rats.

Methods

Male Wistar rats were divided into 3 groups: (i) Sham (n = 4), animals exposed to carotid arteries dissection without clamping; (ii) Control (n = 4), animals exposed to carotid arteries dissection without clamping; (ii) Control (n = 4), animals exposed to carotid arteries dissection without clamping; (ii) Control (

Results

Rats treated with vitamin C presented with a similar behavior as compared to the Sham group in all the three tests (p > 0.05), but it was significantly different from controls (p > 0.05), but it was significantly different from controls (p > 0.05), but it was significantly different from controls (

Conclusion

In the present study, vitamin C was associated with behavioral and motor preservation as well as decreased cerebral MDA levels after induced cerebral ischemia in rats.

Oxidative stress and biochemical markers in prenatally androgenized sheep after neonatal treatment with GnRH agonist

Background

Disruption of the balance between the production of ROS and their removal through enzymatic and non-enzymatic (antioxidant) processes has been proposed as a new mechanism in the pathology of polycystic ovary syndrome (PCOS). Evidence from animal models of PCOS (prenatally androgenized sheep) has suggested that treatment with insulin sensitizers, but not antiandrogens, can reduce increases in ROS.

Materials and methods

In the present study, we investigated the effects of neonatal treatment with a gonadotropin-releasing hormone (GnRH) agonist (leuprolide acetate) on prenatally androgenized sheep with testosterone propionate to determine its impact on oxidative stress molecules (ferric reducing antioxidant power [FRAP], advanced oxidation protein product [AOPP], nitric oxide [NOx], albumin) at 8, 12, and 18 months of age.

Results

Androgenized ewes (but not leuprolide-treated ewes) showed reduced total cholesterol levels associated with a decrease in the ratio of visceral to subcutaneous adiposity (adjusted to abdominal area) as determined by computed tomography. In androgenized ewes at 12 months of age, an increase in subcutaneous fat and relative decrease in the visceral fat compartment did not affect the expression of REDOX markers. At 18 months of age, however, the levels of NOx metabolites decreased in androgenized animals, but remained close to normal in ewes subjected to neonatal treatment with leuprolide acetate. Other oxidative stress parameters (FRAP, AOPP, albumin) did not vary among groups.

Conclusion

Our results demonstrate that the GnRH agonist leuprolide (as a single dose after birth) had weak effects on markers of the oxidative stress balance.

Unlimited sucrose consumption during adolescence generates a depressive-like phenotype in adulthood

Depression is highly prevalent worldwide, but its etiology is not fully understood. An overlooked possible contributor to the epidemic of depression is feeding styles, particularly at early age when the brain is intensely changing. We have previously reported that unlimited sucrose consumption during adolescence leads to enduring changes in brain reward function. Here, we tested the hypothesis that sucrose consumption during adolescence would lead to a 'depressive-like' phenotype. Adolescent male rats were given unlimited access to 5% sucrose in their home cages from postnatal day 30 to postnatal day 46 and their emotional behavior was subsequently examined at adulthood. Sucrose consumption during adolescence caused anhedonia, decreased motivation for saccharin, increased immobility in the forced swim test and exacerbated anxiety-like behavior. Additionally, sucrose consumption during adolescence decreased cell proliferation in the hippocampus in adulthood. Chronic treatment with imipramine (10 mg/kg) normalized behavior and restored cell proliferation in the hippocampus of adult rats with a history of sucrose consumption during adolescence. A similar sucrose consumption starting at adulthood only increases immobility in the forced swim test, suggesting that sucrose intake affects also adults' behavior but to a lesser degree. Overall, our findings reveal an unsuspected protracted effect of sucrose consumption on behavior and suggest that unlimited sucrose consumption during critical periods of brain development may play an important role in the etiology of reward-related disorders such as depression.

Long-term high-protein diet intake reverts weight gain and attenuates metabolic dysfunction on high-sucrose-fed adult rats

Background

Consumption of added sugars has been considered a worldwide public health concern by its association with metabolic syndrome and its comorbidities. Meanwhile, current studies have suggested high-protein diets to promote weight loss and improved metabolic outcomes. Thus, this study aimed to investigate the effects of long-term high-protein diet (HPD, 34.3% protein) intake on high-sucrose-fed rats.

Methods

Weaned male Wistar rats were randomized into two groups: rats fed a standard chow (CT/CT, 10% sucrose) or rats fed a high-sucrose diet (HSD, 25% sucrose) for a 20-week observational period. Subsequently, HS/HS animals were randomized into 3 new groups: rats maintained on HSD diet (HS/HS); rats submitted to HSD replacement by standard chow (HS/CT); and those with HSD replaced by HPD (HS/HP). All groups were followed up for 12 weeks during which we investigated the effects of HPD on body weight, energy intake, obesity development, glicemic/lipid profile, glucose tolerance, insulin resistance, tissue weight (adipose tissue, liver and skeletal muscles), lipolytic activity, liver lipoperoxidation and histology, as well as serum markers of hepatic function.

Results

Post-weaning exposure to HSD led to metabolic syndrome phenotype at adulthood, herein characterized by central obesity, glucose intolerance, dyslipidaemia and insulin resistance. Only HPD feeding was able to revert weight gain and adipose tissue accumulation, as well as restore adipose tissue lipolytic response to sympathetic stimulus. On the other hand, either HPD or withdrawal from HSD promoted very similar metabolic outcomes upon 12-week nutritional intervention. HS/HP and HS/CT rats showed reduced fasting serum levels of glucose, triacylglycerol and total cholesterol, which were correlated with the improvement of peripheral insulin sensitivity, as inferred from kITT and TyG Index values. Both nutritional interventions restored liver morphofunctional patterns, but only HPD restored lipid peroxidation.

Conclusions

Our data showed that 12-week intake of an isocaloric moderately high-protein diet consistently restored high-sucrose-induced central adiposity and obesity in addition to the attenuation of other important metabolic outcomes, such as improvement of glucolipid homeostasis associated to increased insulin sensitivity and reversal of hepatic steatosis. On the other hand, simple withdrawal from high-sucrose consumption also promoted the abovementioned metabolic outcomes with no impact on body weight.

Carbohydrates and cognitive function

PURPOSE OF REVIEW

Recent evidence documents the negative impact of obesity, diabetes mellitus, and other metabolic dysregulation on neurocognitive function. This review highlights a key dietary factor in these relationships: refined carbohydrates.

RECENT FINDINGS

Chronic consumption of refined carbohydrates has been linked to relative neurocognitive deficits across the lifespan. Hippocampal function is especially impacted, but prefrontal and mesolimbic reward pathways may also be altered. Early life exposure to refined carbohydrates, (i.e., prenatal, juvenile, and adolescence periods) may be particularly toxic to cognitive functioning. The impact of acute carbohydrate administration is mixed, with some findings showing benefits while others are neutral or negative. Potential mechanisms of the carbohydrate-cognition relationship include dysregulation in metabolic, inflammatory, and vascular factors, whereas moderators include age, genetic factors, physiological (e.g., glucoregulatory) function and the timing and type of carbohydrate exposure. Critically, the negative neurocognitive impacts of diets high in refined carbohydrates have been shown to be independent of total body weight.

SUMMARY

Neurocognitive deficits induced by a diet high in refined carbohydrates may manifest before overt obesity or metabolic disease onset, suggesting that researchers and providers may need to target subclinical metabolic, inflammatory, and vascular dysregulation factors in efforts to preserve cognitive function across the lifespan.

Effects of high fat or high sucrose diet on behavioral-response to social defeat stress in mice

Stress increases risk for psychopathology, and diet may moderate the impact of stress on mental health. A “Western” diet has been linked to psychopathology in humans; animal studies also show that diet can influence negative valence behavior in the presence or absence of stress, but findings are inconsistent. Contradictions in existing studies may result from differences in macronutrient content of diets and presence of metabolic syndrome. The present study exposed mice to 10 days of high fat or high sucrose diet concurrent with social defeat stress exposure and examined negative valence behavior at acute (<five days) and long-term (>30 days) time points after stress/diet exposure. Predictably, stress increased negative valence behavior in the social interaction, open field, elevated zero maze, and tail suspension tests at the acute time point. While most stress-induced behaviors normalized after the 30-day recovery period, social avoidance was still highly significant for stress-exposed mice, supporting the hypothesis that avoidance of a trauma-related cue persists beyond non-specific anxiety-like behaviors. Supporting the hypothesis that an unhealthy diet contributes to psychopathology, non-stressed mice fed high fat or high sucrose diets spent less time exploring the center of the open field. This effect was no longer present after a 30-day recovery. Intriguingly, mice previously fed either high fat or high sucrose diets exhibited increased rearing behavior in the elevated zero maze 30 days post stress and diet exposure. This finding could be evidence that short-term diet administration can initiate a long-term increase in risk-assessment behavior.

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Social stress increased negative valence in short-term behavioral tests.

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Social avoidance persisted for stress exposed mice thirty days post stress exposure.

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Unhealthy diet decreased exploration in the center of the open field.

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Non-stress, control diet mice had the least anxiety-like behavior in open field.

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Unhealthy diets increased rearing behavior 30 days post stress exposure.

Oxidative stress and metabolic markers in pre- and postnatal polycystic ovary syndrome rat protocols

Background

Several studies have described an enhanced inflammatory status and oxidative stress balance disruption in women with polycystic ovary syndrome (PCOS). However, there is scarce information about redox markers in the blood of androgenized animal models. Here, we evaluated the serum/plasma oxidative stress marker and metabolic parameter characteristics of prenatal (PreN) and postnatal (PostN) androgenized rat models of PCOS.

Materials and methods

For PreN androgenization (n=8), 2.5 mg of testosterone propionate was subcutaneously administered to dams at embryonic days 16, 17, and 18, whereas PostN androgenization (n=7) was accomplished by subcutaneously injecting 1.25 mg of testosterone propionate to animals at PostN day 5. A unique control group (n=8) was constituted for comparison.

Results

Our results indicate that PostN group rats exhibited particular modifications in the oxidative stress marker, an increased plasma ferric-reducing ability of plasma, and an increased antioxidant capacity reflected by higher albumin serum levels. PostN animals also presented increased total cholesterol and triglyceride-glucose levels, suggesting severe metabolic disarrangement.

Conclusion

Study findings indicate that changes in oxidative stress could be promoted by testosterone propionate exposure after birth, which is likely associated with anovulation and/or lipid disarrangement.

Long-term consumption of sugar-sweetened beverage during the growth period promotes social aggression in adult mice with proinflammatory responses in the brain

Overconsumption of sugar-sweetened beverages (SSBs) is known to be a key contributor to the obesity epidemic; however, its effects on behavioral changes are yet to be fully studied. In the present study, we examined the long-term effects of SSB on social aggression in mice. Three-week-old weaned mice started to drink either a 30 w/v% sucrose solution (S30), plain water (CT), or an aspartame solution with sweetness equivalent to the sucrose solution (A30) and continued to drink until they were 11-week-old adults. Aggressive behaviors were assessed by the resident-intruder test. We found that SSB significantly promoted social aggression, accompanied by heightened serum corticosterone and reduced body weight. To understand the underlying mechanism, we performed transcriptome analyses of brain. The profiles of mice on S30 were dramatically different from those on CT or A30. Transcriptional networks related to immunological function were significantly dysregulated by SSB. FACS analysis of mice on S30 revealed increased numbers of inflammatory cells in peripheral blood. Interestingly, the artificial sweetener failed to mimic the effects of sugar on social aggression and inflammatory responses. These results demonstrate that SSB promotes aggressive behaviors and provide evidence that sugar reduction strategies may be useful in efforts to prevent social aggression.