A high fructose diet does not affect amphetamine self-administration or spatial water maze learning and memory in female rats

Mechanisms Underlying Memory Impairment Induced by Fructose

Fructose consumption has increased over the years, especially in adolescents living in urban areas. Growing evidence indicates that daily fructose consumption leads to some pathological conditions, including memory impairment. This review summarizes relevant data describing cognitive deficits after fructose intake and analyzes the underlying neurobiological mechanisms. Preclinical experiments show sex-related deficits in spatial memory; that is, while males exhibit significant imbalances in spatial processing, females seem unaffected by dietary supplementation with fructose. Recognition memory has also been evaluated; however, only female rodents show a significant decline in the novel object recognition test performance. According to mechanistic evidence, fructose intake induces neuroinflammation, mitochondrial dysfunction, and oxidative stress in the short term. Subsequently, these mechanisms can trigger other long-term effects, such as inhibition of neurogenesis, downregulation of trophic factors and receptors, weakening of synaptic plasticity, and long-term potentiation decay. Integrating all these neurobiological mechanisms will help us understand the cellular and molecular processes that trigger the memory impairment induced by fructose.

A High-Sugar Diet Consumption, Metabolism and Health Impacts with a Focus on the Development of Substance Use Disorder: A Narrative Review

Carbohydrates are important macronutrients in human and rodent diet patterns that play a key role in crucial metabolic pathways and provide the necessary energy for proper body functioning. Sugar homeostasis and intake require complex hormonal and nervous control to proper body energy balance. Added sugar in processed food results in metabolic, cardiovascular, and nervous disorders. Epidemiological reports have shown enhanced consumption of sweet products in children and adults, especially in reproductive age and in pregnant women, which can lead to the susceptibility of offspring’s health to diseases in early life or in adulthood and proneness to mental disorders. In this review, we discuss the impacts of high-sugar diet (HSD) or sugar intake during the perinatal and/or postnatal periods on neural and behavioural disturbances as well as on the development of substance use disorder (SUD). Since several emotional behavioural disturbances are recognized as predictors of SUD, we also present how HSD enhances impulsive behaviour, stress, anxiety and depression. Apart from the influence of HSD on these mood disturbances, added sugar can render food addiction. Both food and addictive substances change the sensitivity of the brain rewarding neurotransmission signalling. The results of the collected studies could be important in assessing sugar intake, especially via maternal dietary patterns, from the clinical perspective of SUD prevention or pre-existing emotional disorders. Methodology: This narrative review focuses on the roles of a high-sugar diet (HSD) and added sugar in foods and on the impacts of glucose and fructose on the development of substance use disorder (SUD) and on the behavioural predictors of drugs abuse. The literature was reviewed by two authors independently according to the topic of the review. We searched the PubMed and Scopus databases and Multidisciplinary Digital Publishing Institute open access scientific journals using the following keyword search strategy depending on the theme of the chapter: “high-sugar diet” OR “high-carbohydrate diet” OR “sugar” OR “glucose” OR “fructose” OR “added sugar” AND keywords. We excluded inaccessible or pay-walled articles, abstracts, conference papers, editorials, letters, commentary, and short notes. Reviews, experimental studies, and epidemiological data, published since 1990s, were searched and collected depending on the chapter structure. After the search, all duplicates are thrown out and full texts were read, and findings were rescreened. After the selection process, appropriate papers were included to present in this review.

Jugular Vein Catheter Design and Cocaine Self-Administration Using Mice: A Comprehensive Method

Intravenous self-administration (IVSA) is a behavioral method of voluntary drug intake in animal models which is used to study the reinforcing effects of drugs of abuse. It is considered to have greater face validity in the study of substance use and abuse than other assays, and thus, allows for valuable insight into the neurobiological basis of addiction, and the development of substance abuse disorders. The technique typically involves surgically inserting a catheter into the jugular vein, which enables the infusion of drug solution after the performance of a desired operant behavior. Two nose- poke ports or levers are offered as manipulanda and are randomly assigned as active (reinforced) or inactive (non-reinforced) to allow for the examination of discrimination in the assessment of learning. Here, we describe our methodological approach to this assay in a mouse model, including construction and surgical implantation of a jugular vein catheter, set up of operant chambers, and considerations during each phase of the operant task.

Neonatal intake of oleanolic acid attenuates the subsequent development of high fructose diet-induced non-alcoholic fatty liver disease in rats

Dietary manipulations during the early postnatal period are associated with the development of metabolic disorders including non-alcoholic fatty liver disease (NAFLD) or long-term protection against metabolic dysfunction. We investigated the potential hepatoprotective effects of neonatal administration of oleanolic acid (OA), a phytochemical, on the subsequent development in adulthood, of dietary fructose-induced NAFLD. Male and female suckling rats (n=112) were gavaged with; distilled water (DW), OA (60 mg/kg), high fructose solution (HF; 20% w/v) and OA+HF (OAHF) for 7 days. The rats were weaned onto normal rat chow on day 21 up to day 55. From day 56, half of the rats in each treatment group were continued on plain water or HF as drinking fluid for 8 weeks. Hepatic lipid accumulation and hepatic histomorphometry were then determined. Fructose consumption in adulthood following neonatal fructose intake (HF+F) caused a 47-49% increase in hepatic lipid content of both male and female rats (P<0.05). However, fructose administered in adulthood only, caused a significant increase (P<0.05) in liver lipid content in females only. NAFLD activity scores for inflammation and steatosis were higher in the fructose-fed rats compared with other groups (P<0.05). Steatosis, low-grade inflammation and fibrosis were observed in rats that received HF+F. NAFLD area fraction for fibrosis was three times higher in rats that received fructose neonatally and in adulthood compared with the rats in the negative control group (P<0.05). Treatment with OA during a critical window of developmental plasticity in rats prevented the development of fructose-induced NAFLD.

Acute Effects of Glucose and Fructose Administration on the Neural Correlates of Cognitive Functioning in Healthy Subjects: A Pilot Study

The present randomized double-blinded cross-over study aims to extensively study the neural correlates underpinning cognitive functions in healthy subjects after acute glucose and fructose administration, using an integrative multimodal neuroimaging approach. Five minutes after glucose, fructose, or placebo administration through a nasogastric tube, 12 participants underwent 3 complementary neuroimaging techniques: 2 task-based functional magnetic resonance imaging (fMRI) sequences to assess working memory (N-back) and response inhibition (Go/No-Go) and one resting state fMRI sequence to address the cognition-related fronto-parietal network (FPN) and salience network (SN). During working memory processing, glucose intake decreased activation in the anterior cingulate cortex (ACC) relative to placebo, while fructose decreased activation in the ACC and sensory cortex relative to placebo and glucose. During response inhibition, glucose and fructose decreased activation in the ACC, insula and visual cortex relative to placebo. Resting state fMRI indicated increased global connectivity strength of the FPN and the SN during glucose and fructose intake. The results demonstrate that glucose and fructose lead to partially different partially overlapping changes in regional brain activities that underpin cognitive performance in different tasks.

Effects of high-fructose diets on central appetite signaling and cognitive function

The consumption of fructose has increased tremendously over the last five decades, which is to a large extent due to the development of high-fructose corn syrup (HFCS), a commercial sugar additive that contains high amounts of free fructose. HFCS is often added to processed food and beverages partly because it is a powerful sweetener but even more so because the production is cheap. Although fructose in combination with fiber, vitamins, and minerals, as present in fruits, is a healthy source of energy, isolated fructose, in processed food products has been associated with several health disorders such as insulin resistance and hypertension. Apart from its metabolic consequences, a growing body of literature suggests that free fructose can also affect neuronal systems. High-fructose intake may on the one hand affect central appetite regulation by altering specific components of the endocannabinoid system. On the other hand, it appears to impact on cognitive function by affecting phosphorylation levels of insulin receptor, synapsin 1, and synaptophysin. The present report reviews the recent evidence showing a negative effect of free fructose consumption on central appetite control, as well as cognitive function.

Detection of impaired cognitive function in rat with hepatosteatosis model and improving effect of GLP-1 analogs (exenatide) on cognitive function in hepatosteatosis

The aims of the study were to evaluate (1) detection of cognitive function changing in rat with hepatosteatosis model and (2) evaluate the effect of GLP-1 analog (exenatide) on cognitive function in hepatosteatosis. In the study group, 30% fructose was given in nutrition water to perform hepatosteatosis for 8 weeks to 18 male rats. Six male rats were chosen as control group and had normal nutrition. Fructose nutrition group were stratified into 3 groups. In first group (n = 6), intracerebroventricular (ICV) infusion of exenatide (n = 6) was given. ICV infusion of NaCl (n = 6) was given to second group. And also, the third group had no treatment. And also, rats were evaluated for passive avoidance learning (PAL) and liver histopathology. Mean levels of latency time were statistically significantly decreased in rats with hepatosteatosis than those of normal rats (P < 0.00001). However, mean level of latency time in rats with hepatosteatosis treated with ICV exenatide was statistically significantly increased than that of rats treated with ICV NaCl (P < 0.001). Memory performance falls off in rats with hepatosteatosis feeding on fructose (decreased latency time). However, GLP-1 ameliorates cognitive functions (increased latency time) in rats with hepatosteatosis and releated metabolic syndrome.

Cognitive performance of Göttingen minipigs is affected by diet in a spatial hole-board discrimination test

Consumption of a high energy diet, containing high amounts of saturated fat and refined sugar has been associated with impairment of cognitive function in rodents and humans. We sought to contrast the effect of a high fat/cholesterol, low carbohydrate diet and a low fat, high carbohydrate/sucrose diet, relative to a standard low fat, high carbohydrate minipig diet on spatial cognition with regards to working memory and reference memory in 24 male Göttingen minipigs performing in a spatial hole-board discrimination test. We found that both working memory and reference memory were impaired by both diets relative to a standard minipig diet high in carbohydrate, low in fat and sugar. The different diets did not impact levels of brain-derived neurotrophic factor in brain tissue and neither did they affect circulatory inflammation measured by concentrations of C-reactive protein and haptoglobin in serum. However, higher levels of triglycerides were observed for minipigs fed the diets with high fat/cholesterol, low carbohydrate and low fat, high carbohydrate/sucrose compared to minipigs fed a standard minipig diet. This might explain the observed impairments in spatial cognition. These findings suggest that high dietary intake of both fat and sugar may impair spatial cognition which could be relevant for mental functioning in humans.

Ghrelin, neuropeptide Y, and other feeding-regulatory peptides active in the hippocampus: role in learning and memory

The hippocampus is a brain region of primary importance for neurogenesis, which occurs during early developmental states as well as during adulthood. Increases in neuronal proliferation and in neuronal death with age have been associated with drastic changes in memory and learning. Numerous neurotransmitters are involved in these processes, and some neuropeptides that mediate neurogenesis also modulate feeding behavior. Concomitantly, feeding peptides, which act primarily in the hypothalamus, are also present in the hippocampus. This review aims to ascertain the role of several important feeding peptides in cognitive functions, either through their local synthesis in the hippocampus or through their actions via specific receptors in the hippocampus. A link between neurogenesis and the orexigenic or anorexigenic properties of feeding peptides is discussed.

Way back for fructose and liver metabolism: Bench side to molecular insights

The World Health Organization recommends that the daily intake of added sugars should make up no more than 10% of total energy. The consumption of sugar-sweetened beverages is the main source of added sugars. Fructose, together with glucose, as a component of high fructose corn syrups or as a component of the sucrose molecule, is one of the main sweeteners present in this kind of beverages. Data from prospective and intervention studies clearly point to high fructose consumption, mainly in the form of sweetened beverages, as a risk factor for several metabolic diseases in humans. The incidence of hypertension, nonalcoholic fatty liver disease (NAFLD), dyslipidemia (mainly hypertriglyceridemia), insulin resistance, type 2 diabetes mellitus, obesity, and the cluster of many of these pathologies in the form of metabolic syndrome is higher in human population segments that show high intake of fructose. Adolescent and young adults from low-income families are especially at risk. We recently reviewed evidence from experimental animals and human data that confirms the deleterious effect of fructose on lipid and glucose metabolism. In this present review we update the information generated in the past 2 years about high consumption of fructose-enriched beverages and the occurrence of metabolic disturbances, especially NAFLD, type 2 diabetes mellitus, and metabolic syndrome. We have explored recent data from observational and experimental human studies, as well as experimental data from animal and cell models. Finally, using information generated in our laboratory and others, we provide a view of the molecular mechanisms that may be specifically involved in the development of liver lipid and glucose metabolic alterations after fructose consumption in liquid form.