Control of motivation for sucrose in the paraventricular hypothalamic nucleus by dynorphin peptides and the kappa opioid receptor

The dynorphin peptides are the endogenous ligands for the kappa opioid receptor (KOR) and regulate food intake. Administration of dynorphin-A1-13 (DYN) in the paraventricular hypothalamic nucleus (PVN) increases palatable food intake, and this effect is blocked by co-administration of the orexin-A neuropeptide, which is co-released with DYN in PVN from neurons located in the lateral hypothalamus. While PVN administration of DYN increases palatable food intake, whether it increases food-seeking behaviors has yet to be examined. We tested the effects of DYN and norBNI (a KOR antagonist) on the seeking and consumption of sucrose using a progressive ratio (PR) and demand curve (DC) tasks. In PVN, DYN did not alter the sucrose breaking point in the PR task nor the elasticity or intensity of demand for sucrose in the DC task. Still, DYN reduced the delay in obtaining sucrose and increased licks during sucrose intake in the PR task, irrespective of the co-administration of orexin-A. In PVN, norBNI increased the delay in obtaining sucrose and reduced licks during sucrose intake in the PR task while reducing elasticity but not intensity of demand in the DC task. However, subcutaneous norBNI reduced the breaking point for sucrose and increased the delay in obtaining sucrose in the PR task while reducing the elasticity of demand. Together, these data show different effects of systemic and PVN blockade of KOR on food-seeking, consummatory behaviors, and incentive motivation for sucrose and suggest that KOR activity in PVN is necessary but not sufficient to drive seeking behaviors for palatable food.

Sex-Dependent Metabolic Effects in Diet-Induced Obese Rats following Intermittent Fasting Compared with Continuous Food Restriction

Recently, intermittent fasting has gained relevance as a strategy to lose weight and improve health as an alternative to continuous caloric restriction. However, the metabolic impact and the sex-related differences are not fully understood. The study aimed to compare the response to a continuous or intermittent caloric restriction in male and female rats following a previous induction of obesity through a cafeteria diet by assessing changes in body weight, energy intake, metabolic parameters, and gene expression in liver hepatic and adipose tissue. The continuous restriction reduced the energy available by 30% and the intermittent restriction consisted of a 75% energy reduction on two non-consecutive days per week. The interventions reduced body weight and body fat in both sexes, but the loss of WAT in females was more marked in both models of caloric restriction, continuous and intermittent. Both caloric restrictions improved insulin sensitivity, but more markedly in females, which showed a more pronounced decrease in HOMA-IR score and an upregulation of hepatic IRS2 and Sirt1 gene expression that was not observed in males. These findings suggest the fact that females are more sensitive than males to reduced caloric content in the diet.

Lingual Taste Nerve Transection Alters Food Selection, Relative Macronutrient Intake, and Meal Patterns in Rats Consuming a Cafeteria Diet without Changing Total Energy Intake

The control of ingestive behavior is complex and involves input from many different sources, including the gustatory system. Signals transmitted via the taste nerves trigger responses that promote or discourage ingestion. The lingual taste nerves innervate 70% of taste buds, yet their role in the control of food selection and intake remarkably remains relatively underinvestigated. Here we used our custom five-item Food Choice Monitor to compare postsurgical behavioral responses to chow and a five-choice cafeteria diet (CAF) between male rats that had sham surgery (SHAM) or histologically verified transection of the chorda tympani and glossopharyngeal nerves (2NX). Compared with SHAM rats, 2NX rats ate significantly more of the high-fat CAF foods. The altered food choices led to dramatically increased fat intake and substantially reduced carbohydrate intake by 2NX vs SHAM rats. Furthermore, whether offered chow or CAF, 2NX rats ate fewer, larger meals each day. Eating rates implied that, compared with SHAM, 2NX rats were equally motivated to consume CAF but less motivated to eat chow. Even with these differences, energy intake and weight gain trajectories remained similar between SHAM and 2NX rats. Although some rats experienced CAF before surgery, contrary to our expectations, the effects of prior CAF experience on postsurgical eating were minimal. In conclusion, although total energy intake was unaffected, our results clearly indicate that information from one or both lingual taste nerves has a critical role in food selection, regulation of macronutrient intake, and meal termination but not long-term energy balance.

Weight and Glucose Control in Rats Submitted to Sleeve Gastrectomy with Cafeteria Diet-Induced Obesity

Introduction: Sleeve gastrectomy (SG) has been widely disseminated as a surgical treatment for obesity and associated comorbidities, and currently it is one of the most performed surgeries in the world. Experimental research is becoming increasingly relevant to characterize the pathophysiological mechanisms induced by it. Objective: The aim of this study was to standardize an experimental model of SG in rats with obesity induced using a cafeteria diet (CAF) and evaluate variations in weight and glycemic control after vertical SG, maintaining the CAF. Materials and Methods: Twenty Rattus norvegicus albinus rats, Wistar strain, with an average weight of 250 g were used. The animals were randomized into two groups and underwent 4 weeks of obesity induction before the procedure. In 10 animals of the SG group, vertical SG was performed, and in 10 animals of the control/sham (C) group, simulated surgery was performed, consisting of laparotomy and bidigital compression of the stomach. The animals were followed for a total of 8 weeks, with the weight assessed weekly and fasting blood glucose assessed before the start of the CAF, at the time of surgery, and after 4 weeks of the postoperative period, when they were sacrificed. Results: Before obesity induction, the average weight was 257.8 g in the SG group 266.1 g in the C group. After obesity induction, the average weight was 384 g in the vertical sleeve gastrectomy group and 374.8 g in the C group. In the fourth postoperative week, the average weight was 391.6 g in the VSG group and 436.6 g in the C group. The average blood glucose levels were 88.7, 101.8, and 91.3 mg/dL in the VSG group and 86.6, 103.1, and 109.4 mg/dL in the C group, respectively, before the start of the diet, in the fourth preoperative week, and in the fourth postoperative week. Conclusions: Vertical SG in rats is feasible and promotes glycemic control in the postoperative period. CAF allows induction of obesity and changes in blood glucose.

Relative Recovery of Non-Alcoholic Fatty Liver Disease (NAFLD) in Diet-Induced Obese Rats

Consumption of a high-carbohydrate diet has a critical role in the induction of weight gain and obesity-related pathologies. This study tested the hypothesis that a carbohydrate-rich diet induces weight gain, ectopic fat deposition, associated metabolic risks and development of non-alcoholic fatty liver disease (NAFLD), which are partially reversible following carbohydrate reduction. Sprague Dawley (SD) rats were fed a carbohydrate-enriched cafeteria diet (CAF) or normal chow (NC) ad libitum for 16-18 weeks. In the reversible group (REV), the CAF was replaced with NC for a further 3 weeks (18-21 weeks). Animals fed the CAF diet showed significantly increased body weight compared to those fed NC, accompanied by abnormal changes in their systemic insulin and triglycerides, elevation of hepatic triglyceride and hepatic steatosis. In the REV group, when the CAF diet was stopped, a modest, non-significant weight loss was associated with improvement in systemic insulin and appearance of the liver, with lower gross fatty deposits and hepatic triglyceride. In conclusion, a carbohydrate-enriched diet led to many features of metabolic syndrome, including hyperinsulinemia, while a dietary reduction in this macronutrient, even for a short period, was able to restore normoinsulinemia, and reversed some of the obesity-related hepatic abnormalities, without significant weight loss.

The Nature of Available Choices Affects the Intake and Meal Patterns of Rats Offered a Palatable Cafeteria-Style Diet

Humans choose which foods they will eat from multiple options. The use of cafeteria-style diets with rodent models has increased our understanding of how a multichoice food environment affects eating and health. However, the wide variances in energy density, texture, and the content of micronutrients, fiber, and protein can be interpretatively problematic when human foodstuffs are used to create rodent cafeteria diets. We minimized these differences with a custom rodent cafeteria diet (ROD) that varied similarly to a previously used human-foods cafeteria diet (HUM) in fat and sugar content. Here, we used our custom Five-Item Food Choice Monitor to compare the intake and meal patterns of rats offered ROD and HUM in a crossover design. Compared with chow, rats consumed more calories, sugar, and fat and less protein and carbohydrate while on either of the choice diets (p < 0.05). While energy intake was similar between HUM and ROD, there were differences in the responses. Rats consumed more of the low-fat, low-sugar choice on the ROD compared with the nutritionally similar choice on the HUM leading to differences in fat and carbohydrate intake between the diets (p < 0.05). The stability of macronutrient intake while on either choice diet suggests macronutrient intake is determined by the available foods and is strongly regulated. Therefore, interpretative consideration must be given to the nature of food choices in the context of available options when interpreting cafeteria-diet intake.

Maternal cafeteria diet influences kisspeptin (Kiss1), kisspeptin receptor(Gpr54), and sirtuin (Sirt1) genes, hormonal and metabolic profiles, and reproductive functions in rat offspring in a sex-specific manner†

Kisspeptin (KP, encoded by Kiss1, binding to the Gpr54 receptor) is a neuropeptide conveying information on the metabolic status to the hypothalamic-pituitary-gonadal axis. KP acts together with dynorphin A (encoded by Pdyn) and neurokinin B (encoded by Tac2) to regulate reproduction. KP is crucial for the onset of puberty and is under the control of sirtuin (encoded by Sirt1). We hypothesize that the maternal cafeteria (CAF) diet has adverse effects on the offspring's hormonal, metabolic, and reproductive functions due to sex-specific alterations in the expression of Kiss1, Gpr54, Pdyn, Tac2, and Sirt1 in the hypothalamus, and Kiss1, Gpr54, and Sirt1 in the liver. Rats were fed a CAF diet before pregnancy, during pregnancy, and during lactation. The vaginal opening was monitored. Offspring were sacrificed in three age points: PND 30, PND 35, and PND 60 (females) and PND 40, PND 45, and PND 60 (males). Their metabolic and hormonal status was assessed. mRNA for Kiss1, Gpr54, Pdyn, Tac2, and Sirt1 were measured by real-time PCR in the hypothalamus and/or livers. We found that CAF offspring had lower weight and altered body composition; increased cholesterol and triglyceride levels, sex-specific changes in glucose and insulin levels; sex-dependent changes in Sirt1/Kiss1 mRNA ratio in the hypothalamus; sex-specific alterations in Kiss1 and Sirt1 mRNA in the liver with more diversity in males; and a delayed puberty onset in females. We concluded that the mother's CAF diet leads to sex-specific alterations in metabolic and reproductive outcomes via Kiss1/Gpr54 and Sirt1 systems in offspring.

Quinoa (Chenopodium quinoa Willd.) supplemented cafeteria diet ameliorates glucose intolerance in rats

Quinoa (Chenopodium quinoa Willd.) is a pseudocereal with rich nutritional composition, gluten free, and organoleptic. The primary aim of this study was to elucidate the possible protective roles of quinoa in glucose homeostasis in a model of cafeteria diet-induced obesity. Male Wistar rats (3 weeks of age) were randomly allocated to be fed by; control chow (CON; n = 6), quinoa (QUI; n = 6), cafeteria (CAF; n = 6), or quinoa and cafeteria (CAFQ; n = 6) for 15 weeks. CAFQ resulted in decreased saturated fat, sugar, and sodium intake in comparison with CAF. Compared to CON, CAF increased body weight gain, plasma insulin, plasma glucose, decreased liver IRS-1, AMPK mRNA expressions, and pancreatic β-cell insulin immunoreactivity, and developed hepatocyte degeneration and microvesicular steatosis. Compared to CAF, QUI lowered body weight, plasma glucose, and plasma insulin, increased liver IRS-1 and AMPK mRNA expressions, and pancreatic β-cell insulin immunoreactivity. Compared to CAF, CAFQ lowered plasma glucose, increased liver IRS-1 mRNA expressions, increased pancreatic β-cell insulin immunoreactivity, and lowered hepatocyte degeneration and microvesicular steatosis. Dietary treatments did not influence IRS-2, AKT2, and INSR mRNA expressions. HOMA-IR, HOMA-β, and QUICKI were also similar between groups. Restoration of insulin in CAFQ islets was as well as that of CON and QUI groups. In conclusion, as a functional food, quinoa may be useful in the prevention of obesity and associated metabolic outcomes such as glucose intolerance, disrupted pancreatic β-cell function, hepatic insulin resistance, and lipid accumulation.

The Hepatic Antioxidant System Damage Induced with the Cafeteria (CAF) Diet Is Largely Counteracted Using SCD Probiotics during Development of Male Wistar Rats

The cafeteria (CAF) diet, reflective of predominant Western dietary behaviors, is implicated in hastening weight gain, subsequently resulting in health complications such as obesity, diabetes, and cancer. To this end, it is vital to notice the deleterious consequences of the CAF regimen prior to the onset of complications, which is fundamental for early intervention in the context of numerous diseases. Probiotic-derived postbiotic metabolites have gained attention for their antioxidative properties, offering a potential countermeasure against oxidative stress. This research sought to discern the protective efficacy of SCD Probiotics against liver glutathione system damage arising from the CAF diet during developmental phases. Male Wistar rats, from weaning on day 21 to day 56, were categorized into four groups: a control on a conventional diet; a group on a standard diet enriched with SCD Probiotics; a mixed-diet group comprising both CAF and standard feed; and a combination diet group supplemented with SCD Probiotics. Through the application of real-time PCR, enzyme activity assessments, and quantitative metabolite analyses, our findings highlight the CAF diet's adverse influence on the liver's antioxidant defenses via shifts in gene expression. Yet, the inclusion of SCD Probiotics mostly ameliorated these harmful effects. Remarkably, the positive regulatory influence of SCD Probiotics on the liver's antioxidant system was consistently observed, independent of the CAF diet's presence.

Chromatographic Analyses of Spirulina (Arthrospira platensis) and Mechanism of Its Protective Effects against Experimental Obesity and Hepatic Steatosis in Rats

Background and Objectives: Obesity is currently a major health problem due to fatty acid accumulation and excess intake of energy, which leads to an increase in oxidative stress, particularly in the liver. The main goal of this study is to evaluate the protective effects of spirulina (SP) against cafeteria diet (CD)-induced obesity, oxidative stress, and lipotoxicity in rats. Materials and Methods: The rats were divided into four groups and received daily treatments for eight weeks as follows: control group fed a standard diet (SD 360 g/d); cafeteria diet group (CD 360 g/d); spirulina group (SP 500 mg/kg); and CD + SP group (500 mg/kg, b.w., p.o.) according to body weight (b.w.) per oral (p.o.). Results: Our results show that treatment with a CD increased the weights of the body, liver, and abdominal fat. Additionally, severe hepatic alteration, disturbances in the metabolic parameters of serum, and lipotoxicity associated with oxidative stress in response to the CD-induced obesity were observed. However, SP treatment significantly reduced the liver alteration of CD feed and lipid profile disorder associated with obesity. Conclusions: Our findings suggest that spirulina has a marked potential therapeutic effect against obesity and mitigates disturbances in liver function parameters, histological alterations, and oxidative stress status.

Rhythm and ROS: Hepatic Chronotherapeutic Features of Grape Seed Proanthocyanidin Extract Treatment in Cafeteria Diet-Fed Rats

Polyphenols play a key role in the modulation of circadian rhythms, while the cafeteria diet (CAF) is able to perturb the hepatic biological rhythm and induce important ROS production. Consequently, we aimed to elucidate whether grape seed proanthocyanidin extract (GSPE) administration recovers the CAF-induced hepatic antioxidant (AOX) misalignment and characterize the chronotherapeutic properties of GSPE. For this purpose, Fischer 344 rats were fed a standard diet (STD) or a CAF and concomitantly treated with GSPE at two time-points (ZT0 vs. ZT12). Animals were euthanized every 6 h and the diurnal rhythms of hepatic ROS-related biomarkers, hepatic metabolites, and AOX gene expression were examined. Interestingly, GSPE treatment was able to recover the diurnal rhythm lost due to the CAF. Moreover, GSPE treatment also increased the acrophase of Sod1, as well as bringing the peak closer to that of the STD group. GSPE also corrected some hepatic metabolites altered by the CAF. Importantly, the differences observed at ZT0 vs. ZT12 due to the time of GSPE administration highlight a chronotherapeutic profile on the proanthocyanin effect. Finally, GSPE could also reduce diet-induced hepatic oxidative stress not only by its ROS-scavenging properties but also by retraining the circadian rhythm of AOX enzymes.

The cardioprotective effects of secoisolariciresinol diglucoside (flaxseed lignan) against cafeteria diet-induced cardiac fibrosis and vascular injury in rats: an insight into apelin/AMPK/FOXO3a signaling pathways

Introduction: Fast food is a major risk factor for atherosclerosis, a leading cause of morbidity and mortality in the Western world. Apelin, the endogenous adipokine, can protect against cardiovascular disease via activating its receptor, APJ. Concurrently, secoisolariciresinol diglucoside (SDG), a flaxseed lignan extract (FLE), showed a therapeutic impact on atherosclerosis. The current study aimed to examine the effect of SDG on cafeteria diet (CAFD)-induced vascular injury and cardiac fibrosis via tracking the involvement of the apelin/APJ pathway. Methods: Thirty male rats were allocated into control, FLE-, CAFD-, CAFD/FLE-, and CAFD/FLE/F13A-treated rats, where F13A is an APJ blocker. All treatments lasted for 12 weeks. Results and discussion: The CAFD-induced cardiovascular injury was evidenced by histological distortions, dyslipidemia, elevated atherogenic indices, cardiac troponin I, collagen percentage, glycogen content, and apoptotic markers. CAFD increased both the gene and protein expression levels of cardiac APJ, apelin, and FOXO3a, in addition to increasing endothelin-1, VCAM1, and plasminogen activator inhibitor-1 serum levels and upregulating cardiac MMP-9 gene expression. Moreover, CAFD reduced serum paraoxonase 1 and nitric oxide levels, cardiac AMPK, and nuclear Nrf2 expression. FLE attenuated CAFD-induced cardiovascular injury. Such effect was reduced in rats receiving the APJ blocker, implicating the involvement of apelin/APJ in FLE protective mechanisms. Conclusion: FLE supplementation abrogated CAFD-induced cardiac injury and endothelial dysfunction in an apelin/APJ-dependent manner.

Corrigendum: Impact of short and long exposure to cafeteria diet on food intake and white adipose tissue lipolysis mediated by glucagon-like peptide 1 receptor

[This corrects the article DOI: 10.3389/fendo.2023.1164047.].

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.

Impact of short and long exposure to cafeteria diet on food intake and white adipose tissue lipolysis mediated by glucagon-like peptide 1 receptor

Introduction

The modern food environment facilitates excessive calorie intake, a major driver of obesity. Glucagon-like peptide 1 (GLP1) is a neuroendocrine peptide that has been the basis for developing new pharmacotherapies against obesity. The GLP1 receptor (GLP1R) is expressed in central and peripheral tissues, and activation of GLP1R reduces food intake, increases the expression of thermogenic proteins in brown adipose tissue (BAT), and enhances lipolysis in white adipose tissue (WAT). Obesity decreases the efficiency of GLP1R agonists in reducing food intake and body weight. Still, whether palatable food intake before or during the early development of obesity reduces the effects of GLP1R agonists on food intake and adipose tissue metabolism remains undetermined. Further, whether GLP1R expressed in WAT contributes to these effects is unclear.

Methods

Food intake, expression of thermogenic BAT proteins, and WAT lipolysis were measured after central or peripheral administration of Exendin-4 (EX4), a GLP1R agonist, to mice under intermittent-short exposure to CAF diet (3 h/d for 8 days) or a longer-continuous exposure to CAF diet (24 h/d for 15 days). Ex-vivo lipolysis was measured after EX4 exposure to WAT samples from mice fed CAF or control diet for 12 weeks. .

Results

During intermittent-short exposure to CAF diet (3 h/d for 8 days), third ventricle injection (ICV) and intra-peritoneal administration of EX4 reduced palatable food intake. Yet, during a longer-continuous exposure to CAF diet (24 h/d for 15 days), only ICV EX4 administration reduced food intake and body weight. However, this exposure to CAF diet blocked the increase in uncoupling protein 1 (UCP1) caused by ICV EX4 administration in mice fed control diet. Finally, GLP1R expression in WAT was minimal, and EX4 failed to increase lipolysis ex-vivo in WAT tissue samples from mice fed CAF or control diet for 12 weeks. .

Discussion

Exposure to a CAF diet during the early stages of obesity reduces the effects of peripheral and central GLP1R agonists, and WAT does not express a functional GLP1 receptor. These data support that exposure to the obesogenic food environment, without the development or manifestation of obesity, can alter the response to GLP1R agonists. .

Photoperiod Conditions Modulate Serum Oxylipins Levels in Healthy and Obese Rats: Impact of Proanthocyanidins and Gut Microbiota

Seasonal rhythms are emerging as a key factor influencing gut microbiota and bioactive compounds functionality as well as several physiological processes such as inflammation. In this regard, their impact on the modulation of oxylipins (OXLs), which are important lipid mediators of inflammatory processes, has not been investigated yet. Hence, we aimed to investigate the effects of photoperiods on OXLs metabolites in healthy and obesogenic conditions. Moreover, we evaluated if the impact of proanthocyanidins and gut microbiota on OXLs metabolism is influenced by photoperiod in obesity. To this purpose, Fischer 344 rats were housed under different photoperiod conditions (L6: 6 h light, L12: 12 h light or L18:18 h light) and fed either a standard chow diet (STD) or a cafeteria diet (CAF) for 9 weeks. During the last 4 weeks, obese rats were daily administered with an antibiotic cocktail (ABX), an oral dose of a grape seed proanthocyanidin extract (GSPE), or with their combination. CAF feeding and ABX treatment affected OXLs in a photoperiod dependent-manner. GSPE significantly altered prostaglandin E2 (PGE2) levels, only under L6 and mitigated ABX-mediated effects only under L18. In conclusion, photoperiods affect OXLs levels influenced by gut microbiota. This is the first time that the effects of photoperiod on OXLs metabolites have been demonstrated.

The Benefits of Switching to a Healthy Diet on Metabolic, Cognitive, and Gut Microbiome Parameters Are Preserved in Adult Rat Offspring of Mothers Fed a High-Fat, High-Sugar Diet

SCOPE

Maternal obesity increases the risk of health complications in children, highlighting the need for effective interventions. A rat model of maternal obesity to examine whether a diet switch intervention could reverse the adverse effects of an unhealthy postweaning diet is used.

METHODS AND RESULTS

Male and female offspring born to dams fed standard chow or a high-fat, high-sugar "cafeteria" (Caf) diet are weaned onto chow or Caf diets until 22 weeks of age, when Caf-fed groups are switched to chow for 5 weeks. Adiposity, gut microbiota composition, and place recognition memory are assessed before and after the switch. Body weight and adiposity fall in switched groups but remain significantly higher than chow-fed controls. Nonetheless, the diet switch improves a deficit in place recognition memory observed in Caf-fed groups, increases gut microbiota species richness, and alters β diversity. Modeling indicate that adiposity most strongly predicts gut microbiota composition before and after the switch.

CONCLUSION

Maternal obesity does not alter the effects of switching diet on metabolic, microbial, or cognitive measures. Thus, a healthy diet intervention lead to major shifts in body weight, adiposity, place recognition memory, and gut microbiota composition, with beneficial effects preserved in offspring born to obese dams.

Duodenojejunal Omega Switch Surgery Reduces Oxidative Stress Induced by Cafeteria Diet in Sprague-Dawley Rats

Over-nutrition with cafeteria diet leads to glycemic control failure and subsequent obesity. Bariatric surgery remains the ultimate treatment option, and when complemented with specific dietary protocol, it may mitigate the effects of oxidative stress induced by a cafeteria diet. The study measured antioxidant marker activity: superoxidase dismutase (SOD) and ceruloplasmin (CER), total antioxidant capacity (TAC), and lipid peroxidation marker concentrations: lipofuscin (LS) and malondialdehyde (MDA), in the plasma of 56 Sprague-Dawley rats fed with a cafeteria (HFS) or a control (CD) diet and subjected to duodenojejunal omega switch (DJOS) or control (SHAM) surgery. The diet change after the surgery (CD/HFS or HFS/CD) strongly influenced SOD activity in DJOS- and SHAM-operated rats, but SOD activity was always higher in SHAM-operated rats. Every dietary protocol used in the study increased CER activity, except for the CD/CD combination. Cafeteria diet consumed before or after either of surgeries led to decrease in TAC levels. DJOS and no change in diet reduced MDA levels. DJOS reduced LS levels, but its beneficial effect was deteriorated by selected dietary protocols. The cafeteria diet negatively affected the positive impact of DJOS surgery, but SOD, CER, MDA, and LS were significantly lower in rats that underwent DJOS, suggesting that eight weeks of dietary treatment before and after the surgery did not totally dilapidate the effects of the bariatric treatment.

Brain site-specific regulation of hedonic intake by orexin and DYN peptides: role of the PVN and obesity

The orexin peptides promote hedonic intake and other reward behaviors through different brain sites. The opioid dynorphin peptides are co-released with orexin peptides but block their effects on reward in the ventral tegmental area (VTA). We previously showed that in the paraventricular hypothalamic nucleus (PVN), dynorphin and not orexin peptides enhance hedonic intake, suggesting they have brain-site-specific effects. Obesity alters the expression of orexin and dynorphin receptors, but whether their expression across different brain sites is important to hedonic intake is unclear. We hypothesized that hedonic intake is regulated by orexin and dynorphin peptides in PVN and that hedonic intake in obesity correlates with expression of their receptors. Here we show that in mice, injection of DYN-A_1-13 (an opioid dynorphin peptide) in the PVN enhanced hedonic intake, whereas in the VTA, injection of OXA (orexin-A, an orexin peptide) enhanced hedonic intake. In PVN, OXA blunted the increase in hedonic intake caused by DYN-A_1-13. In PVN, injection of norBNI (opioid receptor antagonist) reduced hedonic intake but a subsequent OXA injection failed to increase hedonic intake, suggesting that OXA activity in PVN is not influenced by endogenous opioid activity. In the PVN, DYN-A_1-13 increased the intake of the less-preferred food in a two-food choice task. In obese mice fed a cafeteria diet, orexin 1 receptor mRNA across brain sites involved in hedonic intake correlated with fat preference but not caloric intake. Together, these data support that orexin and dynorphin peptides regulate hedonic intake in an opposing manner with brain-site-specific effects.

Grape Seed Proanthocyanidins Mitigate the Disturbances Caused by an Abrupt Photoperiod Change in Healthy and Obese Rats

Variations in the light/dark cycle and obesogenic diets trigger physiological and behavioral disorders. Proanthocyanidins, in addition to their healthy properties, have recently demonstrated a modulating effect on biological rhythms. Therefore, the aim of this study was to evaluate the administration of a grape seed proanthocyanidin-rich extract (GSPE) to mitigate the disruption caused by a sudden photoperiod change in healthy and cafeteria (CAF)-diet obese rats. For this, 48 photoperiod-sensitive Fischer 344 rats were fed standard or CAF diets for 6 weeks under a standard (12 h light/day, L12) conditions. Then, rats were switched to a long (18 h light/day, L18) or short (6 h light/day, L6) photoperiod and administered vehicle or GSPE (25 mg/kg) for 1 week. Body weight (BW) and food intake (FI) were recorded weekly. Animal activity and serum hormone concentrations were studied before and after the photoperiod change. Hormone levels were measured both at 3 h (ZT3) and 15 h (ZT15) after the onset of light. Results showed the impact of the CAF diet and photoperiod on the BW, FI, activity, and hormonal status of the animals. GSPE administration resulted in an attenuation of the changes produced by the photoperiod disruption. Specifically, GSPE in L6 CAF-fed rats reduced serum corticosterone concentration, restoring its circadian rhythm, increased the T3-to-T4 ratio, and increased light phase activity, while under L18, it decreased BW and testosterone concentration and increased the animal activity. These results suggest that GSPE may contribute to the adaptation to the new photoperiods. However, further studies are needed to elucidate the metabolic pathways and processes involved in these events.

Etanercept Prevents Endothelial Dysfunction in Cafeteria Diet-Fed Rats

Obesity is associated with endothelial dysfunction and this relationship is probably mediated in part by inflammation. Objective: The current study evaluated the effects of etanercept, a tumor necrosis factor-alpha (TNF-α) inhibitor, on endothelial and vascular reactivity, endothelial nitric oxide synthase (eNOS) immunoreactivity, and serum and aortic concentrations of TNF-α in a diet-induced rat model. Design and results: Male weanling Wistar rats were exposed to a standard diet and cafeteria diet (CD) for 12 weeks and etanercept was administered during CD treatment. Isolated aortas of the rats were used for isometric tension recording. Carbachol-induced relaxant responses were impaired in CD-fed rats, while etanercept treatment improved these endothelium-dependent relaxations. No significant change was observed in papaverine- and sodium nitroprusside (SNP)-induced relaxant responses. eNOS expression decreased in CD-fed rats, but no change was observed between etanercept-treated CD-fed rats and control rats. CD significantly increased both the serum and the aortic levels of TNF-α, while etanercept treatment suppressed these elevated levels. CD resulted in a significant increase in the body weight of the rats. Etanercept-treated (ETA) CD-fed rats gained less weight than both CD-fed and control rats.

Gut Seasons: Photoperiod Effects on Fecal Microbiota in Healthy and Cafeteria-Induced Obese Fisher 344 Rats

Gut microbiota and biological rhythms are emerging as key factors in the modulation of several physiological and metabolic processes. However, little is known about their interaction and how this may affect host physiology and metabolism. Several studies have shown oscillations of gut microbiota that follows a circadian rhythmicity, but, in contrast, variations due to seasonal rhythms have not been sufficiently investigated yet. Thus, the goal of this study was to investigate the impact of different photoperiods, which mimic seasonal changes, on fecal microbiota composition and how this interaction affects diet-induced obesity development. To this aim, Fisher 344 male rats were housed under three photoperiods (L6, L12 and L18) and fed with standard chow diet or cafeteria diet (CAF) for 9 weeks. The 16S ribosomal sequencing of collected fecal samples was performed. The photoperiod exposure significantly altered the fecal microbiota composition under L18, especially in CAF-fed rats. Moreover, these alterations were associated with changes in body weight gain and different fat parameters. These findings suggest a clear impact of seasonal rhythms on gut microbiota, which ultimately translates into different susceptibilities to diet-induced obesity development. This is the first time to our knowledge that the photoperiod impact on gut microbiota composition has been described in an obesity context although further studies are needed in order to elucidate the mechanisms involved.

Male Rat Offspring Are More Impacted by Maternal Obesity Induced by Cafeteria Diet than Females-Additive Effect of Postweaning Diet

Maternal obesity increases the risk of health complications in offspring, but whether these effects are exacerbated by offspring exposure to unhealthy diets warrants further investigation. Female Sprague-Dawley rats were fed either standard chow (n = 15) or ‘cafeteria’ (Caf, n = 21) diets across pre-pregnancy, gestation, and lactation. Male and female offspring were weaned onto chow or Caf diet (2–3/sex/litter), forming four groups; behavioural and metabolic parameters were assessed. At weaning, offspring from Caf dams were smaller and lighter, but had more retroperitoneal (RP) fat, with a larger effect in males. Maternal Caf diet significantly increased relative expression of ACACA and Fasn in male and female weanling liver, but not CPT-1, SREBP and PGC1; PPARα was increased in males from Caf dams. Maternal obesity enhanced the impact of postweaning Caf exposure on adult body weight, RP fat, liver mass, and plasma leptin in males but not females. Offspring from Caf dams appeared to exhibit reduced anxiety-like behaviour on the elevated plus maze. Hepatic CPT-1 expression was reduced only in adult males from Caf fed dams. Post weaning Caf diet consumption did not alter liver gene expression in the adult offspring. Maternal obesity exacerbated the obesogenic phenotype produced by postweaning Caf diet in male, but not female offspring. Thus, the impact of maternal obesity on adiposity and liver gene expression appeared more marked in males. Our data underline the sex-specific detrimental effects of maternal obesity on offspring.

Meal Patterns and Food Choices of Female Rats Fed a Cafeteria-Style Diet Are Altered by Gastric Bypass Surgery

After Roux-en-Y gastric bypass surgery (RYGB), rats tend to reduce consumption of high-sugar and/or high-fat foods over time. Here, we sought to investigate the behavioral mechanisms underlying these intake outcomes. Adult female rats were provided a cafeteria diet comprised of five palatable foodstuffs varying in sugar and fat content and intake was monitored continuously. Rats were then assigned to either RYGB, or one of two control (CTL) groups: sham surgery or a nonsurgical control group receiving the same prophylactic iron treatments as RYGB rats. Post-sur-gically, all rats consumed a large first meal of the cafeteria diet. After the first meal, RYGB rats reduced intake primarily by decreasing the meal sizes relative to CTL rats, ate meals more slowly, and displayed altered nycthemeral timing of intake yielding more daytime meals and fewer nighttime meals. Collectively, these meal patterns indicate that despite being motivated to consume a cafeteria diet after RYGB, rats rapidly learn to modify eating behaviors to consume foods more slowly across the entire day. RYGB rats also altered food preferences, but more slowly than the changes in meal patterns, and ate proportionally more energy from complex carbohydrates and protein and proportionally less fat. Overall, the pattern of results suggests that after RYGB rats quickly learn to adjust their size, eating rate, and distribution of meals without altering meal number and to shift their macronutrient intake away from fat; these changes appear to be more related to postingestive events than to a fundamental decline in the palatability of food choices.

Cafeteria Diet Impacts the Body Weight and Energy Expenditure of Brown Norway Rats in an Apparent Age Dependent Manner, but Has no Effect on Muscle Anabolic Sensitivity to Nutrition

While obesity blunts the ability of muscle to mount a protein synthetic response to an amino acid infusion in older adults, it is unclear if this insensitivity to nutrition persists long term and in response to complete foods is unknown. To address this, young (2 months old) and old (17–20 months old) Brown Norway rats were randomized to receive either chow or a 12 wk diet of calorie-dense human foods. At wk 10 drinking water was supplemented with 2% heavy water, followed 2 weeks later by a flooding dose of [²H₅]-phenylalanine and an oral leucine bolus, allowing the short and long-term effects of age and diet on muscle protein synthesis rates to be determined. The experimental diet increased energy intake in both young (7.4 ± 0.9%) and old (18.2 ± 1.8%) animals (P < 0.01), but only led to significant increases in body weight in the former (young: 10.2 ± 3.0% (P < 0.05) and old: 3.1 ± 5.1% (NS) vs. age-matched controls). Notably, energy expenditure in response to the cafeteria diet was increased in old animals only (chow: 5.1 ± 0.4; cafe: 8.2 ± 1.6 kcal.kg b.w⁻¹.h⁻¹; P < 0.05). Gastrocnemius protein fractional synthetic rates in response to either an acute leucine bolus or two weeks of feeding were equivalent across groups irrespective of age or diet. Rodents in old age appear capable of preventing weight gain in response to a calorie-dense diet by increasing energy expenditure while maintaining the anabolic sensitivity of muscle to nutrition; the mechanisms of which could have important implications for the aging obese human.

Gut Microbiome Composition and Metabolic Status Are Differently Affected by Early Exposure to Unhealthy Diets in a Rat Model

Childhood is a critical stage of development during which diet can have profound influence on the microbiota–host interactions, leading to potentially lifelong impacts. This study aimed to investigate whether the consumption of cafeteria diet (CAFD) and sugary drinks during early rat life alters the structure of the gut microbial community and the metabolic activity. Four-week-old male Wistar rats (n = 27) were fed a standard chow diet with ad libitum access to water (CD) or to sucrose solution (HSD), and a third group was fed with CAFD and a sucrose solution for 14 weeks. HSD and CAFD consumption induced alterations in Firmicutes to Bacteroidetes ratio, Proteobacteria, and Verrucomicrobia. HSD increased the abundance of Barnesiella, whereas CAFD induced a depletion of Saccharibacteria. CAFD increased total white adipose tissue (WAT) weight (p < 0.0005) compared to CD. When CAFD was compared to HSD, a significant difference was found only for retroperitoneal WAT (p < 0.0005). Unhealthy diet-fed groups presented higher glucose (p < 0.0005), total cholesterol and creatinine serum levels (p < 0.005) compared to the CD rats. Early-life consumption of HSD, and of CAFD even more so, can have long-lasting negative effects on metabolic function. The gut microbiota communities were distinctively perturbed by diet composition.

Chronic Effect of a Cafeteria Diet and Intensity of Resistance Training on the Circulating Lysophospholipidome in Young Rats

The daily practice of physical exercise and a balanced diet are recommended to prevent metabolic syndrome (MetS). As MetS is a multifactorial disorder associated with the development of serious diseases, the advancement of comprehensive biomarkers could aid in an accurate diagnosis. In this regard, it is known that gut microbiota is altered in MetS, and especially, lipid metabolites species are highly modified, thus emerging as potential biomarkers. In preliminary studies, we observed that alterations in serum lysoglycerophospholipids (Lyso-PLs) were shared between animals with diet-induced MetS and those performing resistance exercises assiduously. Therefore, our objective was the targeted determination of the lysophospholipidome in young rats fed a standard (ST) or a cafeteria diet (CAF) and submitted to different training intensities to evaluate its potential as a biomarker of a detrimental lifestyle. Targeted metabolomics focused on lysophosphatidylcholines (Lyso-PCs) and lysophosphatidylethanolamines (Lyso-PEs) and multivariate statistics were used to achieve an integral understanding. Chronic intake of CAF altered the serological levels of both lipid subclasses. Twenty-two Lyso-PLs were significantly altered by CAF, from which we selected Lyso-PCs (14:0), (17:1) and (20:2) and Lyso-PEs (18:2) and (18:3) as they were enough to achieve an optimal prediction. The main effect of physical training was decreased Lyso-PEs levels with disparities among training intensities for each diet. We concluded that an examination of the lysophospholipidome reveals the general state of the metabolome in young female rats, especially due to intake of an MetS-inducing diet, thus highlighting the importance of this family of compounds in lipid disorders.

Glucagon Shows Higher Sensitivity than Insulin to Grapeseed Proanthocyanidin Extract (GSPE) Treatment in Cafeteria-Fed Rats

The endocrine pancreas plays a key role in metabolism. Procyanidins (GSPE) targets β-cells and glucagon-like peptide-1 (GLP-1)-producing cells; however, there is no information on the effects of GSPE on glucagon. We performed GSPE preventive treatments administered to Wistar rats before or at the same time as they were fed a cafeteria diet during 12 or 17 weeks. We then measured the pancreatic function and GLP-1 production. We found that glucagonemia remains modified by GSPE pre-treatment several weeks after the treatment has finished. The animals showed a higher GLP-1 response to glucose stimulation, together with a trend towards a higher GLP-1 receptor expression in the pancreas. When the GSPE treatment was administered every second week, the endocrine pancreas behaved differently. We show here that glucagon is a more sensitive parameter than insulin to GSPE treatments, with a secretion that is highly linked to GLP-1 ileal functionality and dependent on the type of treatment.

Proteomic and Structural Manifestations of Cardiomyopathy in Rat Models of Obesity and Weight Loss

Obesity cardiomyopathy increases the risk of heart failure and death. Obesity is curable, leading to the restoration of the heart phenotype, but it is not clear if there are any after-effects of obesity present after weight loss. We characterize the proteomic landscape of obesity cardiomyopathy with an evaluation of whether the cardiac phenotype is still shaped after weight loss. Cardiomyopathy was validated by cardiac hypertrophy, fibrosis, oversized myocytes, and mTOR upregulation in a rat model of cafeteria diet-induced developmental obesity. By global proteomic techniques (LC-MS/MS) a plethora of molecular changes was observed in the heart and circulation of obese animals, suggesting abnormal utilization of metabolic substrates. This was confirmed by increased levels of cardiac ACSL-1, a key enzyme for fatty acid degradation and decreased GLUT-1, a glucose transporter in obese rats. Calorie restriction and weight loss led to the normalization of the heart's size, but fibrosis was still excessive. The proteomic compositions of cardiac tissue and plasma were different after weight loss as compared to control. In addition to morphological consequences, obesity cardiomyopathy involves many proteomic changes. Weight loss provides for a partial repair of the heart's architecture, but the trace of fibrotic deposition and proteomic alterations may occur.

A restricted cafeteria diet ameliorates biometric and metabolic profile in a rat diet-induced obesity model

The administration of anti-obesity bioactive compounds and/or functional foods in rodents fed energy restriction diets based on chow food can be difficult to interpret. We propose an energy restricted cafeteria (CAF) diet as a dietetic intervention to be combined with other therapies. Postweaning male rats were fed standard chow, CAF diet or 30% energy restricted CAF diet (CAF-R) for 8 weeks. The CAF-R diet lowered energy intake and the increase of body weight and body mass index due to the CAF diet, lead to an intermediate feed efficiency, and dampened the CAF diet-induced alterations on body composition, serum levels of triacylglycerides and NEFAs, and insulin resistance. These effects were associated with diminished Ucp1, Nrf1 and Tfam1 gene expression in brown adipose tissue. In conclusion, the CAF-R diet ameliorated obesity and related metabolic disorders induced by a regular CAF diet, turning it in a useful tool to study anti-obesity compounds.

Antiobesity Activity of Elateriospermum tapos Shell Extract in Obesity-Induced Sprague Dawley Rats

Obesity is one of the risk factors associated with cardiovascular diseases, hypertension, abnormal liver function, diabetes, and cancers. Orlistat is currently available to treat obesity, but it is associated with adverse side effects. Natural resources are widely used for obesity treatment. Hence, this study aimed to investigate the anti-obesity activity of Elateriospermum tapos (E. tapos) shell extract in obesity induced Sprague Dawley rats. The rats' obesity was induced by a high-fat (HF) diet made up of 50% standard rat pellet, 20% milk powder, 6% corn starch, and 24% ghee and a cafeteria (CAF) diet such as chicken rolls, salty biscuits, cakes, and cheese snacks. A hot aqueous method for the extraction of E. tapos shells was applied by using 500 mL of distilled water for about 24 h. Various dosages of E. tapos shell extract (10 mg/kg, 100 mg/kg, and 200 mg/kg) were used. At the end of the study, body weight, caloric intake, organ weight, lipid profile, lipoprotein lipase (LPL) activity, and histopathology analysis were carried out. E. tapos shell extract treated groups showed a reduction in body weight, positive lipid-lowering effect, decrements in triglyceride accumulation and LPL activity, and positive improvement in histopathology analysis. A dose of 200 mg/kg showed the most effective result compared to 10 mg/kg and 100 mg/kg doses.

Does a high-fat diet-induced obesity model brown adipose tissue thermogenesis? A systematic review

INTRODUCTION

In this systematic review, we analysed studies that assessed the brown adipose tissue (BAT) activity in the high-fat/cafeteria diet model of obesity in rats.

MATERIAL AND METHODS

Scopus, PubMed, Embase, and ScienceDirect databases were searched from January 2017 to November 2017. Using specific combinations of medical subject heading (MeSH) descriptors, seven papers remained after the inclusion and exclusion criteria.

RESULTS

Most papers showed an increase in BAT thermogenesis in rodents fed high-fat/cafeteria diet. Some studies did not mention the diet composition or housing temperature, and the most of them investigated the thermogenesis superficially, being limited to the analysis of the UCP 1 expression.

CONCLUSIONS

Despite the consolidated use of high-fat/cafeteria diets as a model to induce obesity, the identification of the energy expenditure arm has been slow, especially the direct quantitative assessment of the contribution of BAT to the increase in metabolic rate in rats fed a cafeteria/high-fat diet.

Mucuna pruriens Administration Minimizes Neuroinflammation and Shows Anxiolytic, Antidepressant and Slimming Effects in Obese Rats

This study evaluated the effect of Mucuna pruriens (MP) administration on neuroinflammation and behavioral and murinometric parameters in obese rats. Proximate composition, oligosaccharide and phenolic compound profile of MP were determined. Wistar adult male rats were randomized into healthy (HG) and obese group (OG). The HG consumed a control chow diet while OG consumed a cafeteria diet for eight weeks. Then, they were subdivided into: Healthy (HG); Healthy with MP administration (HGMP); Obese (OG); Obese with MP administration (OGMP), with the consumption of the respective diets remaining for another eight weeks, in addition to gavage with MP extract to supplemented groups (750 mg/kg weight). MP presented a composition rich in proteins and phenolic compounds, especially catechin, in addition to 1-kestose and levodopa. Supplementation reduced food intake, body weight, and thoracic and abdominal circumferences in obese rats. MP showed anxiolytic and antidepressant effects and reduced morphological damage and expression of interleukin 6 in the hippocampus of obese rats. MP treatment showed satietogenic, slimming, anxiolytic and antidepressant effects, besides to minimizing hippocampal neuroinflammation in obese rats. Our results demonstrated the potential anti-obesity of MP which are probably related to the high content of bioactive compounds present in this plant extract.

Cafeteria Diet and High-Fructose Rodent Models of NAFLD Differ in the Metabolism of Important PUFA and Palmitoleic Acid without Additional Influence of Sex

The objective of this study was to evaluate the influence of high-fat (HF) and cafeteria diet (CAF) diets and sex on the metabolism of important fatty acids in the liver and perirenal fat tissue. Dietary treatments induced changes in the fatty acid profile in comparison to the untreated group, but the characteristic differences between treated groups were also observable. The HF diet induced an increase in the content of C16:1n-7 and C18:1n-7 in the liver phospholipids (PL) and triglycerides (TG) and perirenal fat tissue compared to the control and CAF diet. The CAF diet induced a more drastic decrease in both n-3 and n-6 polyunsaturated fatty acids (PUFA), including depletion of eicosapentaenoic acid (EPA). The CAF diet also increased the content of n-6 docosapentaenoic acid (DPAn-6) in the liver and decreased it in the perirenal fat. Sex also had a significant influence on the fatty acid profile, but the variables with the highest differences between the CAF and HF treatments were identical in the male and female rats. In this study, we have established that two dietary models of non-alcoholic fatty liver disease (NAFLD) led to characteristic changes in the hepatic and perirenal fat fatty acid profile, in contrast to the control diet and in comparison with each other. These differences could play an important role in the interpretation of the experimental results of nutritional studies.

Time-Restricted Feeding Improves Body Weight Gain, Lipid Profiles, and Atherogenic Indices in Cafeteria-Diet-Fed Rats: Role of Browning of Inguinal White Adipose Tissue

Time-restricted feeding (TRF) showed a potent effect in preventing obesity and improving metabolicoutcomes in several animal models of obesity. However, there is, as of yet, scarce evidence concerning its effectiveness against obesogenic challenges that more accurately mimic human Western diets, such as the cafeteria diet. Moreover, the mechanism for its efficacy is poorly understood. White adipose browning has been linked to body weight loss. Herein, we tested whether TRF has the potential to induce browning of inguinal white adipose tissue (iWAT) and to attenuate obesity and associated dyslipidemia in a cafeteria-diet-induced obesity model. Male Wistar rats were fed normal laboratory chow (NC) or cafeteria diet (CAF) for 16 weeks and were subdivided into two groups that were subjected to either ad libitum (ad lib, A) or TRF (R) for 8 h per day. Rats under the TRF regimen had a lower body weight gain and adiposity than the diet-matchedad lib rats, despite equivalent levels of food intake and locomotor activity. In addition, TRF improved the deranged lipid profile (total cholesterol (TC), triglycerides (TG), high-density lipoprotein (HDL-c), low-density lipoprotein (LDL-c)) and atherogenic indices (atherogenic index of plasma (AIP), atherogenic coefficient (AC), coronary risk index (CRI) in CAF-fed rats. Remarkably, TRF resulted in decreased size of adipocytes and induced emergence of multilocular brown-like adipocytes in iWAT of NC- and CAF-fed rats. Protein expression of browning markers, such as uncoupling protein-1 (UCP1) and peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC1α), were also up-regulated in the iWAToftime-restricted NC- or CAF-fed rats. These findings suggest that a TRF regimen is an effective strategy to improve CAF diet-induced obesity, probably via a mechanismthe involving WAT browning process.

Brief daily access to cafeteria-style diet impairs hepatic metabolism even in the absence of excessive body weight gain in rats

Numerous nutritional approaches aimed at reducing body weight have been developed as a strategy to reduce obesity. Most of these interventions rely on reducing caloric intake or limiting calories access to a few hours per day. In this work, we analyzed the effects of the extended (24 hours/day) or restricted (1 hour/day) access to a cafeteria-style (CAF) diet, on rat body weight and hepatic lipid metabolism, with respect to control rats (CTR) fed with a standard chow diet. The body weight gain of restricted-fed rats was not different from CTR, despite the slightly higher total caloric intake, but resulted significantly lower than extended-fed rats, which showed a CAF diet-induced obesity and a dramatically higher total caloric intake. However, both CAF-fed groups of rats showed, compared to CTR, unhealthy serum and hepatic parameters such as higher serum glucose level, lower HDL values, and increased hepatic triacylglycerol and cholesterol amount. The hepatic expression and activity of key enzymes of fatty acid synthesis, acetyl-CoA carboxylase (ACC), and fatty acid synthase (FAS), was similarly reduced in both CAF-fed groups of rats with respect to CTR. Anyway, while in extended-fed rats this reduction was associated to a long-term mechanism involving sterol regulatory element-binding protein-1 (SREBP-1), in restricted-fed animals a short-term mechanism based on PKA and AMPK activation occurred in the liver. Furthermore, hepatic fatty acid oxidation (FAO) and oxidative stress resulted significantly increased in extended, but not in restricted-fed rats, as compared to CTR. Overall, these results demonstrate that although limiting the total caloric intake might successfully fight obesity development, the nutritional content of the diet is the major determinant for the health status.

Resveratrol attenuates metabolic, sperm, and testicular changes in adult Wistar rats fed a diet rich in lipids and simple carbohydrates

High-fat diets affect male reproduction and sexual function. Therefore, we evaluated the effects of prolonged resveratrol administration on the metabolic, sperm, and testicular parameters of rats fed a cafeteria diet. Male Wistar rats were divided at weaning into control (C, n = 20) and cafeteria (CAF, n = 16) groups. At 3 months, half of them were given daily supplementations of resveratrol (C-R, n = 10; CAF-R, n = 8) at a dosage of 30 mg kg^-1 body mass for 2 months. Animals were killed at 5 months of age, and blood, spermatozoa, and testes were collected for further analysis. Data were analyzed by one-way ANOVA, and P < 0.05 was considered statistically significant. The CAF diet promoted hyperglycemia (P < 0.0001), and treatment with resveratrol reversed this condition (P < 0.0001). The CAF diet reduced sperm viability and motility, while resveratrol improved these parameters (P < 0.05). Regarding testicular morphology, the height of the seminiferous epithelium was reduced in the CAF group compared with that of the C group (P = 0.0007). Spermatogenic cell proliferation was also reduced in the CAF group compared with that of the C group. However, the CAF-R showed an increase in cell proliferation rate compared with that of the untreated CAF group (P = 0.0024). Although it did not modify body mass, the consumption of a CAF diet promoted hyperglycemia, adverse testicular morphology remodeling, and abnormal sperm, which were attenuated by treatment with resveratrol, thus suggesting a protective effect of this antioxidant on spermatogenesis.

Metabolomics Elucidates Dose-Dependent Molecular Beneficial Effects of Hesperidin Supplementation in Rats Fed an Obesogenic Diet

Metabolic syndrome (MetS) is a global epidemic concern. Polyphenols are proposed as good candidates for its prevention, although their mechanisms are not fully understood. The gut microbiota seems to play a key role in polyphenol beneficial effects. Here, we assessed the effects of the citrus polyphenol hesperidin combining an untargeted metabolomics approach, which has an inherent potential to elucidate the host-microbiome interplay, with extensive anthropometric and biochemical characterizations and integrating metabolomics results with our previous 16S rRNA bacterial sequencing data. The rats were fed either a standard or an obesogenic cafeteria diet (CAF) for 17 weeks. After nine weeks, rats were supplemented with vehicle; low- (H1), or high- (H2) hesperidin doses. CAF animals developed MetS features. Hesperidin supplementation in CAF rats decreased the total cholesterol, LDL-C, and free fatty acids. The highest hesperidin dose also ameliorated blood pressure, insulin sensitivity, and decreased markers of arterial stiffness and inflammation. Metabolomics revealed an improvement of the lipidomic profile, decreases in circulating amino acids, and lower excretions of inflammation- and oxidative stress-related metabolites. Bacteroidaceae increases in the CAF-H2 group paralleled higher excretions of microbial-derived metabolites. Overall, our results provide detailed insights into the molecular effects of hesperidin on MetS and suggest that it is a promising prebiotic for the treatment of MetS and related conditions.

The Role of Mitochondria in Sex-Dependent Differences in Hepatic Steatosis and Oxidative Stress in Response to Cafeteria Diet-Induced Obesity in Mice

Female mice fed a cafeteria diet (FCaf) develop higher liver steatosis and oxidative stress than males (MCaf) as a consequence of unresolved ER stress. Here, we investigated whether mitochondria play a role in this sex difference. The isolated mitochondria from FCaf showed more signs of oxidative stress than those of MCaf, correlated with a reduced content of GSH, increased amount of reactive oxygen species (ROS), and lower activities of enzymes involved in ROS neutralisation. Mitochondria from FCaf and MCaf livers exhibited lower rates of succinate-driven state III respiration and reduced ATPase activity in intact coupled mitochondria compared to their controls fed a standard diet (FC and MC), with no differences between the sexes. Fatty acid oxidation in mitochondria and peroxisomes was higher in MCaf and FCaf compared to their respective controls. In the intact perfused liver, there was no difference between sex or diet regarding the fatty acid oxidation rate. These results indicated that cafeteria diet did not affect mitochondrial energy metabolism, even in FCaf livers, which have higher steatosis and cellular oxidative stress. Nevertheless, the increase in mitochondrial ROS generation associated with a decrease in the antioxidant defence capacity, probably contributes to inducing or reinforcing the ER stress in FCaf livers.

Evaluation of the effect of cafeteria diet on the kidney Na,K-ATPase activity, and oxidative stress

In this study, renal tissue, subdivided into the cortex and medulla of Wistar rats subjected to a cafeteria diet (CAF) for 24 days or to normal diet, was used to analyze whether the renal enzyme Na,K-ATPase activity was modified by CAF diet, as well as to analyze the α1 subunit of renal Na,K-ATPase expression levels. The lipid profile of the renal plasma membrane and oxidative stress were verified. In the Na,K-ATPase activity evaluation, no alteration was found, but a significant decrease of 30% in the cortex was detected in the α1 subunit expression of the enzyme. There was a 24% decrease in phospholipids in the cortex of rats submitted to CAF, a 17% increase in cholesterol levels in the cortex, and a 23% decrease in the medulla. Lipid peroxidation was significantly increased in the groups submitted to CAF, both in the cortical region, 29%, and in the medulla, 35%. Also, a reduction of 45% in the glutathione levels was observed in the cortex and medulla with CAF. CAF showed a nearly two-fold increase in glutathione peroxidase (GPX) activity in relation to the control group in the cortex and a 59% increase in the GPx activity in the medulla. In conclusion, although the diet was administered for a short period of time, important results were found, especially those related to the lipid profile and oxidative stress, which may directly affect renal function.

Oxidative Imbalance and Kidney Damage in Cafeteria Diet-Induced Rat Model of Metabolic Syndrome: Effect of Bergamot Polyphenolic Fraction

Obesity is a potent risk factor for kidney disease as it increases the possibility of developing diabetes and hypertension, and it has a direct impact on the development of chronic kidney disease and end-stage renal disease. In this study, we tested the effect of bergamot polyphenolic fraction in a cafeteria with diet-fed rats, an excellent experimental model for studying human metabolic syndrome, as it is able to induce severe obesity with insulin resistance and high plasma triglyceride levels more efficiently than a traditional lard-based high-fat diet used in rodent models. We analyzed the plasmatic oxidative balance by photometric tests, and the expression of cytoplasmic antioxidant enzymes (superoxide dismutase 1 and glutatione S-tranferasi P1) and apoptotic markers (Caspase 8 and 9) in kidney tissues by Western blot analysis. Our results clearly showed that the cafeteria diet induces a marked pro-oxidant effect: significant reduction of plasmatic antioxidant capacity; downregulation of cytoplasmic antioxidant enzymes expression; and activation of apoptotic pathways. All these hallmarks of redox disequilibrium were mitigated by treatment with polyphenolic fraction of bergamot, highlighting its antioxidant effect in the metabolic syndrome. Our data show that the link between obesity and renal damage could be represented by oxidative stress.

Intake of an Obesogenic Cafeteria Diet Affects Body Weight, Feeding Behavior, and Glucose and Lipid Metabolism in a Photoperiod-Dependent Manner in F344 Rats

We previously demonstrated that chronic exposure to different photoperiods induced marked variations in several glucose and lipid metabolism-related parameters in normoweight Fischer 344 (F344) rats. Here, we examined the effects of the combination of an obesogenic cafeteria diet (CAF) and the chronic exposure to three different day lengths (L12, 12 h light/day; L18, 18 h light/day; and L6, 6 h light/day) in this rat strain. Although no changes were observed during the first 4 weeks of adaptation to the different photoperiods in which animals were fed a standard diet, the addition of the CAF for the subsequent 7 weeks triggered profound physiologic and metabolic alterations in a photoperiod-dependent manner. Compared with L12 rats, both L6 and L18 animals displayed lower body weight gain and cumulative food intake in addition to decreased energy expenditure and locomotor activity. These changes were accompanied by differences in food preferences and by a sharp upregulation of the orexigenic genes Npy and Ghsr in the hypothalamus, which could be understood as a homeostatic mechanism for increasing food consumption to restore body weight control. L18 rats also exhibited higher glycemia than the L6 group, which could be partly attributed to the decreased pAkt2 levels in the soleus muscle and the downregulation of Irs1 mRNA levels in the gastrocnemius muscle. Furthermore, L6 animals displayed lower whole-body lipid utilization than the L18 group, which could be related to the lower lipid intake and to the decreased mRNA levels of the fatty acid transporter gene Fatp1 observed in the soleus muscle. The profound differences observed between L6 and L18 rats could be related with hepatic and muscular changes in the expression of circadian rhythm-related genes Cry1, Bmal1, Per2, and Nr1d1. Although further research is needed to elucidate the pathophysiologic relevance of these findings, our study could contribute to emphasize the impact of the consumption of highly palatable and energy dense foods regularly consumed by humans on the physiological and metabolic adaptations that occur in response to seasonal variations of day length, especially in diseases associated with changes in food intake and preference such as obesity and seasonal affective disorder.

Potential Involvement of Peripheral Leptin/STAT3 Signaling in the Effects of Resveratrol and Its Metabolites on Reducing Body Fat Accumulation

Bioactive compounds such as polyphenols have increased in importance in recent years, and among them, resveratrol (3,5,4′-trihydroxy-trans-stilbene) has generated great interest as an anti-obesity agent. Recent investigations have highlighted the importance of leptin signaling in lipid metabolism in peripheral organs. The aims of this study were (1) to investigate whether resveratrol can reduce fat accumulation in peripheral tissues by increasing their leptin sensitivity and (2) to identify which resveratrol-derived circulating metabolites are potentially involved in these metabolic effects. Serum leptin levels and the leptin signaling pathway were assessed in diet-induced obese rats. Moreover, serum metabolites of resveratrol were studied by ultra-high performance liquid chromatography–mass spectrometry (UHPLC-MSⁿ). The daily consumption of 200 mg/kg of resveratrol, but not doses of 50 and 100 mg/kg, reduced body weight and fat accumulation in obese rats and restored leptin sensitivity in the periphery. These effects were due to increases in sirtuin 1 activity in the liver, leptin receptors in muscle and protection against endoplasmic reticulum (ER)-stress in adipose tissue. In general, the resveratrol metabolites associated with these beneficial effects were derived from both phase II and microbiota metabolism, although only those derived from microbiota increased proportionally with the administered dose of resveratrol. In conclusion, resveratrol reversed leptin resistance caused by diet-induced obesity in peripheral organs using tissue-specific mechanisms.

Metabolic dysfunction in a rat model of early-life scarcity-adversity: Modulatory role of cafeteria diet

NEW FINDINGS

What is the central question of this study? Early-life adversity is associated with increased risk for obesity and metabolic dysfunction. However, it is unclear whether obesity and metabolic dysfunction result from coping strategies to deal with adversity-related emotional dysregulation, a direct programming of systems regulating metabolic function, or a combination of both. What is the main finding and its importance? Early-life adversity increases vulnerability to later-life obesity and metabolic dysfunction, indicating that genetics and adult lifestyle are not the only determinants of obesity and related metabolic dysfunction. Moreover, consumption of cafeteria diet exacerbated metabolic dysfunction associated with early-life adversity, suggesting that poor dietary choices might have a bigger impact in the context of early-life adversity.

ABSTRACT

Early-life adversity has become recognized as an important factor contributing to adult obesity and associated metabolic dysfunction. However, it is unclear whether obesity and metabolic dysfunction associated with early-life adversity result from coping strategies to deal with adversity-related emotional dysregulation, a direct programming of systems regulating metabolic function, or a combination. Interestingly, both early-life adversity and later-life dietary choices affect immune function, favouring pro-inflammatory mechanisms that are associated with obesity-related metabolic dysfunction. To investigate the unique and/or interactive effects of early-life adversity and later-life dietary choices for increased vulnerability to obesity and metabolic dysfunction, and specifically the role of the immune system in this vulnerability, we combined a naturalistic rat model of early-life scarcity-adversity with a rat model of obesity, the cafeteria diet. Our results indicate that early-life adversity alone induces insulin resistance, reduces pancreatic insulin secretion, plasma concentrations of triglycerides and cholesterol, and increases fasting glucose and tumour necrosis factor-α plasma concentrations. Importantly, animals exposed to adverse rearing were more vulnerable to metabolic dysregulation associated with the cafeteria diet, given that they consumed more energy, showed more severe hepatic steatosis and increased concentrations of the pro-inflammatory cytokine interleukin-1β than normally reared animals fed the cafeteria diet. Together, our results suggest that early-life adversity negatively programmes physiological systems that regulate metabolic function and increases vulnerability to obesity and metabolic dysfunction in adulthood. These results highlight the intrinsic relationship between the quality of the early postnatal environment and later-life dietary choices on adult health outcomes.

Consumption of Cherry out of Season Changes White Adipose Tissue Gene Expression and Morphology to a Phenotype Prone to Fat Accumulation

The aim of this study was to determine whether the consumption of cherry out of its normal harvest photoperiod affects adipose tissue, increasing the risk of obesity. Fischer 344 rats were held over a long day (LD) or a short day (SD), fed a standard diet (STD), and treated with a cherry lyophilizate (CH) or vehicle (VH) (n = 6). Biometric measurements, serum parameters, gene expression in white (RWAT) and brown (BAT) adipose tissues, and RWAT histology were analysed. A second experiment with similar conditions was performed (n = 10) but with a cafeteria diet (CAF). In the STD experiment, Bmal1 and Cry1 were downregulated in the CHSD group compared to the VHSD group. Pparα expression was downregulated while Ucp1 levels were higher in the BAT of the CHSD group compared to the VHSD group. In the CAF-fed rats, glucose and insulin serum levels increased, and the expression levels of lipogenesis and lipolysis genes in RWAT were downregulated, while the adipocyte area increased and the number of adipocytes diminished in the CHSD group compared to the VHSD group. In conclusion, we show that the consumption of cherry out of season influences the metabolism of adipose tissue and promotes fat accumulation when accompanied by an obesogenic diet.

A Trypsin Inhibitor from Tamarind Reduces Food Intake and Improves Inflammatory Status in Rats with Metabolic Syndrome Regardless of Weight Loss

Trypsin inhibitors are studied in a variety of models for their anti-obesity and anti-inflammatory bioactive properties. Our group has previously demonstrated the satietogenic effect of tamarind seed trypsin inhibitors (TTI) in eutrophic mouse models and anti-inflammatory effects of other trypsin inhibitors. In this study, we evaluated TTI effect upon satiety, biochemical and inflammatory parameters in an experimental model of metabolic syndrome (MetS). Three groups of n = 5 male Wistar rats with obesity-based MetS received for 10 days one of the following: (1) Cafeteria diet; (2) Cafeteria diet + TTI (25 mg/kg); and (3) Standard diet. TTI reduced food intake in animals with MetS. Nevertheless, weight gain was not different between studied groups. Dyslipidemia parameters were not different with the use of TTI, only the group receiving standard diet showed lower very low density lipoprotein (VLDL) and triglycerides (TG) (Kruskal–Wallis, p < 0.05). Interleukin-6 (IL-6) production did not differ between groups. Interestingly, tumor necrosis factor-alpha (TNF-α) was lower in animals receiving TTI. Our results corroborate the satietogenic effect of TTI in a MetS model. Furthermore, we showed that TTI added to a cafeteria diet may decrease inflammation regardless of weight loss. This puts TTI as a candidate for studies to test its effectiveness as an adjuvant in MetS treatment.

Leptin signal transduction underlies the differential metabolic response of LEW and WKY rats to cafeteria diet

Although the effect of genetic background on obesity-related phenotypes is well established, the main objective of this study is to determine the phenotypic responses to cafeteria diet (CAF) of two genetically distinct inbred rat strains and give insight into the molecular mechanisms that might be underlying. Lewis (LEW) and Wistar-Kyoto (WKY) rats were fed with either a standard or a CAF diet. The effects of the diet and the strain in the body weight gain, food intake, respiratory quotient, biochemical parameters in plasma as well as in the expression of genes that regulate leptin signalling were determined. Whereas CAF diet promoted weight gain in LEW and WKY rats, as consequence of increased energy intake, metabolic management of this energy surplus was significantly affected by genetic background. LEW and WKY showed a different metabolic profile, LEW rats showed hyperglycaemia, hypertriglyceridemia and high FFA levels, ketogenesis, high adiposity index and inflammation, but WKY did not. Leptin signalling, and specifically the LepRb-mediated regulation of STAT3 activation and Socs3 gene expression in the hypothalamus were inversely modulated by the CAF diet in LEW (upregulated) and WKY rats (downregulated). In the present study, we show evidence of gene-environment interactions in obesity exerted by differential phenotypic responses to CAF diet between LEW and WKY rats. Specifically, we found the leptin-signalling pathway as a divergent point between the strain-specific adaptations to diet.

Effect of Angiotensin(1-7) on Heart Function in an Experimental Rat Model of Obesity

Aim: Obesity is a risk factor for the development of cardiovascular diseases. Recently it was shown that overexpression of the Mas-receptor antagonist angiotensin(1-7) could prevent from diet-induced obesity. However, it remained unclear whether diet-induced obesity and angiotensin(1-7) overexpression might also have effects on the cardiovascular system in these rats.

Methods:Twenty three male Sprague Dawley rats were fed with standard chow (SD+chow, n = 5) or a cafeteria diet (SD+CD, n = 6) for 5 months. To investigate the effect of angiotensin(1-7) transgenic rats, expressing an angiotensin(1-7)-producing fusion protein in testis were used. These transgenic rats also received a 5 month's feeding period with either chow (TGR+chow, n = 6) or cafeteria diet (TGR+CD, n = 6), respectively. Hemodynamic measurements (pressure-volume loops) were carried out to assess cardiac function and blood pressure. Subsequently, hearts were explanted and investigated according to the Langendorff technique. Furthermore, cardiac remodeling in these animals was investigated histologically.

Results:After 5 months cafeteria diet feeding rats showed a significantly increased body weight, which could be prevented in transgenic rats. However, there was no effect on cardiac performance after cafeteria diet in non-transgenic and transgenic rats. Moreover, overexpression of angiotensin(1-7) deteriorated cardiac contractility as indicated by impaired dp/dt. Furthermore, histological analysis revealed that cafeteria diet led to myocardial fibrosis in both, control and transgenic rats and this was not inhibited by an overproduction of angiotensin(1-7).

Conclusion:These results indicate that an overexpression of circulating angiotensin(1-7) prevents a cafeteria diet-induced increase in body weight, but does not affect cardiac performance in this experimental rat model of obesity. Furthermore, overexpression of angiotensin(1-7) alone resulted in an impairment of cardiac function.

Consuming a low-fat diet from weaning to adulthood reverses the programming of food preferences in male, but not in female, offspring of 'junk food'-fed rat dams

AIM

This study aimed to determine whether the negative effects of maternal 'junk food' feeding on food preferences and gene expression in the mesolimbic reward system could be reversed by weaning the offspring onto a low-fat diet.

METHODS

Offspring of control (n = 11) and junk food-fed (JF, n = 12) dams were weaned onto a standard rodent chow until 6 weeks (juvenile) or 3 months (adult). They were then given free access to both chow and junk food for 3 weeks and food preferences determined. mRNA expression of key components of the mesolimbic reward system was determined by qRT-PCR at 6 weeks, 3 and 6 months of age.

RESULTS

In the juvenile group, both male and female JF offspring consumed more energy and carbohydrate during the junk food exposure at 6 weeks of age and had a higher body fat mass at 3 months (P < 0.05). Female juvenile JF offspring had higher tyrosine hydroxylase, dopamine receptors and dopamine active transporter expression in the ventral tegmental area (P < 0.05). In the adult group, there was no difference between control and JF offspring in energy and macronutrient intakes during exposure to junk food; however, female JF offspring had a higher body fat mass at 6 months (P < 0.05).

CONCLUSION

These results suggest that the effects of perinatal junk food exposure on food preferences and fat mass can be reversed by consuming a low-fat diet from weaning to adulthood in males. Females, however, retain a higher propensity for diet-induced obesity even after consuming a low-fat diet for an extended period after weaning.

Cafeteria diet inhibits insulin clearance by reduced insulin-degrading enzyme expression and mRNA splicing

Insulin clearance plays a major role in glucose homeostasis and insulin sensitivity in physiological and/or pathological conditions, such as obesity-induced type 2 diabetes as well as diet-induced obesity. The aim of the present work was to evaluate cafeteria diet-induced obesity-induced changes in insulin clearance and to explain the mechanisms underlying these possible changes. Female Swiss mice were fed either a standard chow diet (CTL) or a cafeteria diet (CAF) for 8 weeks, after which we performed glucose tolerance tests, insulin tolerance tests, insulin dynamics, and insulin clearance tests. We then isolated pancreatic islets for ex vivo glucose-stimulated insulin secretion as well as liver, gastrocnemius, visceral adipose tissue, and hypothalamus for subsequent protein analysis by western blot and determination of mRNA levels by real-time RT-PCR. The cafeteria diet induced insulin resistance, glucose intolerance, and increased insulin secretion and total insulin content. More importantly, mice that were fed a cafeteria diet demonstrated reduced insulin clearance and decay rate as well as reduced insulin-degrading enzyme (IDE) protein and mRNA levels in liver and skeletal muscle compared with the control animals. Furthermore, the cafeteria diet reduced IDE expression and alternative splicing in the liver and skeletal muscle of mice. In conclusion, a cafeteria diet impairs glucose homeostasis by reducing insulin sensitivity, but it also reduces insulin clearance by reducing IDE expression and alternative splicing in mouse liver; however, whether this mechanism contributes to the glucose intolerance or helps to ameliorate it remains unclear.