Cafeteria diet-induced obesity plus chronic stress alter serum leptin levels

Minireview: Glucocorticoid-Leptin Crosstalk: Role of Glucocorticoid-Leptin Counterregulation in Metabolic Homeostasis and Normal Development

Glucocorticoids and leptin are two important hormones that regulate metabolic homeostasis by controlling appetite and energy expenditure in adult mammals. Also, glucocorticoids and leptin strongly counterregulate each other, such that chronic stress-induced glucocorticoids upregulate the production of leptin and leptin suppresses glucocorticoid production directly via action on endocrine organs and indirectly via action on food intake. Altered glucocorticoid or leptin levels during development can impair organ development and increase the risk of chronic diseases in adults, but there are limited studies depicting the significance of glucocorticoid-leptin interaction during development and its impact on developmental programming. In mammals, leptin-induced suppression of glucocorticoid production is critical during development, where leptin prevents stress-induced glucocorticoid production by inducing a period of short-hyporesponsiveness when the adrenal glands fail to respond to certain mild to moderate stressors. Conversely, reduced or absent leptin signaling increases glucocorticoid levels beyond what is appropriate for normal organogenesis. The counterregulatory interactions between leptin and glucocorticoids suggest the potential significant involvement of leptin in disorders that occur from stress during development.

The impact of subchronic hypercaloric and restriction diets on sexual behavior, serum testosterone, and prostate histology in rats

The role of diet in health is crucial, with calorie intake playing a significant role. Hypercaloric diets (HD) often lead to adipose tissue accumulation and increased risk of chronic diseases, including reproductive impairments. By contrast, restriction diets (RD) help with weight loss, improve cardiovascular function, and ameliorate reproduction. Herein we sought to investigate the impact of subchronic HD and RD on body weight, sexual behavior, serum testosterone and prostate histology in rats. Hence, 10-week old male rats gained sexual experience during five trials with ovariectomized, hormone-primed females. Then at postnatal week PW15 the males were organized in three groups, depending on the feeding they received until PW18: HD, RD and standard diet (SD). During PW19-22 they were tested for sexual behavior, and at PW23 were euthanized for prostate histology (hematoxylin & eosin stain) and hormone analysis. Results indicated that HD males increased their body weight (16-23%) compared to SD and RD. Furthermore, HD males showed 65% less testosterone than RD males. The prostate of HD males revealed histological alterations, including a notable increase in epithelium height and other abnormal features, while no changes were observed in the performance of sexual behavior between HD and RD, although HD appeared to facilitate ejaculation when compared to SD. The histological features of RD males were comparable to SD males. Accordingly, we argue that subchronic modifications in calorie intake can alter body weight (in HD), serum testosterone levels (HD and RD in opposite directions), and prostate histology (in HD), while having no immediate effect on male sexual behavior.

Transcranial Direct Current Stimulation (tDCS) Promotes state-dependent Effects on Neuroinflammatory and Behavioral Parameters in rats Chronically Exposed to Stress and a Hyper-Palatable Diet

Chronic stress is a common condition affecting health, often associated with unhealthy eating habits. Transcranial direct current stimulation (tDCS) has been proposed to address these issues. Thus, this research investigated the effects of tDCS on biometric, behavioral, and neurochemical parameters in chronically stressed rats fed a hyper-palatable cafeteria diet (CAFD). The study lasted 8 weeks, with CAFD exposure and/or chronic restraint stress model (CRS - 1 h/day, 5 days/week, for 7 weeks) started concurrently. tDCS or sham sessions were applied between days 42 and 49 (0.5 mA, 20 min/day). CAFD increased body weight, caloric consumption, adiposity, and liver weight. It also altered central parameters, reducing anxiety and cortical levels of IL-10 and BDNF. In turn, the CRS resulted in increased adrenals in rats with standard diet (SD), and anxiety-like and anhedonic behaviors in rats with CAFD. tDCS provided neurochemical shifts in CAFD-fed stressed rats increasing central levels of TNF-α and IL-10, while in stressed rats SD-fed induced a decrease in the adrenals weight, relative visceral adiposity, and serum NPY levels. These data demonstrated the anxiolytic effect of CAFD and anxiogenic effect of stress in CAFD-fed animals. In addition, tDCS promoted state-dependent effects on neuroinflammatory and behavioral parameters in rats chronically exposed to stress and a hyper-palatable diet. These findings provide primary evidence for additional mechanistic and preclinical studies of the tDCS technique for stress-related eating disorders, envisioning clinical applicability.

The role of apelinergic system in metabolism and reproductive system in normal and pathological conditions: an overview

Lifestyle changes have made metabolic disorders as one of the major threats to life. Growing evidence demonstrates that obesity and diabetes disrupt the reproductive system by affecting the gonads and the hypothalamus-pituitary-gonadal (HPG) axis. Apelin, an adipocytokine, and its receptor (APJ) are broadly expressed in the hypothalamus nuclei, such as paraventricular and supraoptic, where gonadotropin-releasing hormone (GnRH) is released, and all three lobes of the pituitary, indicating that apelin is involved in the control of reproductive function. Moreover, apelin affects food intake, insulin sensitivity, fluid homeostasis, and glucose and lipid metabolisms. This review outlined the physiological effects of the apelinergic system, the relationship between apelin and metabolic disorders such as diabetes and obesity, as well as the effect of apelin on the reproductive system in both gender. The apelin-APJ system can be considered a potential therapeutic target in the management of obesity-associated metabolic dysfunction and reproductive disorders.

Changes in the Histological Structure of Adrenal Glands and Corticosterone Level after Whey Protein or Bee Pollen Supplementation in Running and Non-Running Rats

Due to the many health-promoting properties of bee pollen and whey protein, both products are widely used as dietary supplements. According to these reports on their health-promoting properties, the aim of our study is to assess whether these products can influence the structure and function of the adrenal glands in rats. Thirty male Wistar rats were divided into six equal groups. Among them, there were three groups which included non-running rats and three groups which included running rats. Both of these running (n = 3) and non-running (n = 3) groups included non-supplemented (control groups), bee-pollen-supplemented groups, and whey-protein-supplemented groups. After 8 weeks, the rats were decapitated, their adrenal glands were collected, and paraffin slides were prepared. Then, staining according to the standard H&E and Masson's trichrome protocols was performed. Fecal and urine samples were collected prior to the end of the study to measure corticosterone levels. In the group of non-running rats, the consumption of bee pollen was noted to be significantly higher when compared to the group of running rats (p < 0.05). The thickness of the particular adrenal cortex layers was similar among all of the groups (p > 0.05). The statistically significant changes in the microscopic structure of the adrenal glands, especially regarding cell nuclei diameter and structure, as well as the architecture of sinusoids, were observed between the groups. Moreover, urine corticosterone concentrations were found to vary between all of the analyzed groups (p < 0.05). These results indicate that both bee pollen and whey protein have limited stress-reducing potential.

Endoplasmic reticulum stress inhibition ameliorated WFS1 expression alterations and reduced pancreatic islets' insulin secretion induced by high-fat diet in rats

Endoplasmic reticulum (ER) stress is involved in the development of glucose homeostasis impairment. When ER stress occurs, the unfolded protein response (UPR) is activated to cope with it. One of the UPR components is WFS1 (Wolfram syndrome 1), which plays important roles in ER homeostasis and pancreatic islets glucose-stimulated insulin secretion (GSIS). Accordingly and considering that feeding high-fat food has a major contribution in metabolic disorders, this study aimed to investigate the possible involvement of pancreatic ER stress in glucose metabolism impairment induced by feeding high-fat diet (HFD) in male rats. After weaning, the rats were divided into six groups, and fed on normal diet and HFD for 20 weeks, then 4-phenyl butyric acid (4-PBA, an ER stress inhibitor) was administered. Subsequently, in all groups, after performing glucose tolerance test, the animals were dissected and their pancreases were removed to extract ER, islets isolation and assessment of GSIS. Moreover, the pancreatic ER stress [binding of immunoglobulin protein (BIP) and enhancer-binding protein homologous protein (CHOP)] and oxidative stress [malondialdehyde (MDA), glutathione (GSH) and catalase] biomarkers as well as WFS1 expression level were evaluated. HFD decreased pancreatic WFS1 protein and GSH levels, and enhanced pancreatic catalase activity, MDA content, BIP and CHOP protein and mRNA levels as well as Wfs1 mRNA amount. Accordingly, it increased BIP, CHOP and WFS1 protein levels in the extracted ER of pancreas. In addition, the HFD caused glucose intolerance, and decreased the islets' GSIS and insulin content. However, 4-PBA administration restored the alterations. It seems that, HFD consumption through inducing pancreatic ER stress, altered WFS1 expression levels, reduced the islets' GSIS and insulin content and finally impaired glucose homeostasis.

Kinin B1 receptor deficiency protects mice fed by cafeteria diet from abnormal glucose homeostasis

The kallikrein–kinin system has been implicated in body weight and glucose homeostasis. Their major effectors act by binding to the kinin B2 and B1 receptors. It was assessed the role of the kinin B1 receptor in weight and glucose homeostasis in B1 receptor knockout mice (B1RKO) subjected to a cafeteria diet (CAF). Wild-type (WT) and B1RKO male mice (C57BL/6 background; 8 weeks old) were fed a standard diet (SD) or CAF for 14 weeks, ad libitum, and four groups were formed: WT-SD; B1RKO-SD; WT-CAF; B1RKO-CAF. Body weight and food intake were assessed weekly. It was performed glucose tolerance (GTT) and insulin tolerance tests (ITT), and HOMA-IR, HOMA-β and HOMA-β* 1/HOMA-IR were calculated. Islets from WT and B1RKO were isolated in order to measure the insulin secretion. Western blot was used to assess the hepatic AKT phosphorylation and qPCR to assess gene expression. CAF induced a higher body mass gain in B1RKO compared to WT mice. CAF diet increased epididymal fat depot mass, hepatic fat infiltration and hepatic AKT phosphorylation in both genotypes. However, B1RKO mice presented lower glycemic response during GTT when fed with CAF, and a lower glucose decrease in the ITT. This higher resistance was overcomed with higher insulin secretion when stimulated by high glucose, resulting in higher glucose uptake in the GTT when submitted to CAF, despite lower insulin sensitivity. Islets from B1RKO delivered 4 times more insulin in 3-month-old mice than islets from WT. The higher insulin disposition index and high insulin delivery of B1RKO can explain the decreased glucose excursion during GTT. In conclusion, CAF increased the β-cell function in B1RKO mice, compensated by the diet-induced insulin resistance and resulting in a healthier glycemic response despite the higher weight gain.

Global Proteome Profiling of the Temporal Cortex of Female Rats Exposed to Chronic Stress and the Western Diet

The increasing consumption of highly processed foods with high amounts of saturated fatty acids and simple carbohydrates is a major contributor to the burden of overweight and obesity. Additionally, an unhealthy diet in combination with chronic stress exposure is known to be associated with the increased prevalence of central nervous system diseases. In the present study, the global brain proteome approach was applied to explore protein alterations after exposure to the Western diet and/or stress. Female adult rats were fed with the Western diet with human snacks and/or subjected to chronic stress induced by social instability for 12 weeks. The consumption of the Western diet resulted in an obese phenotype and induced changes in the serum metabolic parameters. Consuming the Western diet resulted in changes in only 5.4% of the proteins, whereas 48% of all detected proteins were affected by chronic stress, of which 86.3% were down-regulated due to this exposure to chronic stress. However, feeding with a particular diet modified stress-induced changes in the brain proteome. The down-regulation of proteins involved in axonogenesis and mediating the synaptic clustering of AMPA glutamate receptors (Nptx1), as well as proteins related to metabolic processes (Atp5i, Mrps36, Ndufb4), were identified, while increased expression was detected for proteins involved in the development and differentiation of the CNS (Basp1, Cend1), response to stress, learning and memory (Prrt2), and modulation of synaptic transmission (Ncam1, Prrt2). In summary, global proteome analysis provides information about the impact of the combination of the Western diet and stress exposure on cerebrocortical protein alterations and yields insight into the underlying mechanisms and pathways involved in functional and morphological brain alterations as well as behavioral disturbances described in the literature.

The Anti-Obesity Potential of Cyperus rotundus Extract Containing Piceatannol, Scirpusin A and Scirpusin B from Rhizomes: Preclinical and Clinical Evaluations

PURPOSE

Obesity is a complex medical problem that increases the risk of other diseases like diabetes, cardiovascular diseases, and fatty liver disease. The present study evaluated the efficacy and safety of Cyperus rotundus rhizome extract (CRE), standardized to contain Piceatannol, Scirpusin A, and Scirpusin B (5% total Stilbenoids) in overweight individuals. The mechanism of activity was evaluated in a diet-induced mice model of obesity and adipocytes in vitro.

MATERIALS AND METHODS

The efficacy, safety, and tolerability of CRE were evaluated in 30 obese individuals with a BMI of 30 to 40 kg/m² for 90 days in a randomized, double-blind, parallel-group, placebo-controlled study. In vitro studies were carried out in differentiated 3T3 L1 adipocytes, and the therapeutic efficacy was evaluated in high-fat diet-induced obese mice.

RESULTS

The pilot clinical study showed a reduction in body weight with a significant decrease in waist circumference and BMI. The serum lipid profile showed a significant improvement in CRE-treated individuals. The extract was well tolerated, and no adverse effects were reported at the end of the study. CRE showed a dose-dependent adipogenesis reduction in vitro with an IC₅₀ value of 9.39 μg/mL, while oral administration of CRE reduced weight gain in diet-induced obese mice. The efficacy in mice was associated with reduced levels of leptin, corticosteroids, and serum lipid levels, with no adverse effects.

CONCLUSION

CRE has anti-adipogenic properties, is safe for human consumption, and effectively manages weight and hypercholesterolemia in overweight individuals.

Effects of Gundelia tournefortii L. on biochemical parameters, antioxidant activities and DNA damage in a rat model of experimental obesity

The present study was designed to investigate the effects of Gundelia tournefortii L. plant extract on different tissues in terms of DNA damage, biochemical and antioxidant parameter values in rats with high-calorie diets. With this aim, Wistar albino male rats were divided into 4 groups containing 6 rats each and the study was completed over 12 weeks duration. At the end of the implementation process over the 12 weeks, rats were sacrificed and blood and tissue samples were obtained. Analyses were performed on blood and tissue samples. According to results for DNA damage (8-OHdG), in brain tissue the OG2 group was significantly reduced compared to the NC group. For MDA results in liver tissue, OG1 and OG2 groups were determined to increase by a significant degree compared to the control group, while the OG2 group was also increased significantly compared to the obese group. In terms of the other parameters, comparison between the groups linked to consumption of a high calorie diet (HCD) and administration of Gundelia tournefortii L. in terms of antioxidant activities and serum samples obtained statistically significant results. Gundelia tournefortii L. plant extracts had effects that may be counted as positive on antioxidant parameter activity and were especially identified to improve DNA damage and MDA levels in brain tissues. Additionally, consumption of Gundelia tournefortii L. plant extract in the diet may have antiobesity effects; thus, it should be evaluated for use as an effective weight-loss method and as a new therapeutic agent targeting obesity.

Decreased Glucocorticoid Signaling Potentiates Lipid-Induced Inflammation and Contributes to Insulin Resistance in the Skeletal Muscle of Fructose-Fed Male Rats Exposed to Stress

The modern lifestyle brings both excessive fructose consumption and daily exposure to stress which could lead to metabolic disturbances and type 2 diabetes. Muscles are important points of glucose and lipid metabolism, with a crucial role in the maintenance of systemic energy homeostasis. We investigated whether 9-week fructose-enriched diet, with and without exposure to 4-week unpredictable stress, disturbs insulin signaling in the skeletal muscle of male rats and evaluated potential contributory roles of muscle lipid metabolism, glucocorticoid signaling and inflammation. The combination of fructose-enriched diet and stress increased peroxisome proliferator-activated receptors-α and -δ and stimulated lipid uptake, lipolysis and β-oxidation in the muscle of fructose-fed stressed rats. Combination of treatment also decreased systemic insulin sensitivity judged by lower R-QUICKI, and lowered muscle protein content and stimulatory phosphorylations of insulin receptor supstrate-1 and Akt, as well as the level of 11β-hydroxysteroid dehydrogenase type 1 and glucocorticoid receptor. At the same time, increased levels of protein tyrosine phosphatase-1B, nuclear factor-κB, tumor necrosis factor-α, were observed in the muscle of fructose-fed stressed rats. Based on these results, we propose that decreased glucocorticoid signaling in the skeletal muscle can make a setting for lipid-induced inflammation and the development of insulin resistance in fructose-fed stressed rats.

Nicotinamide riboside reduces cardiometabolic risk factors and modulates cardiac oxidative stress in obese Wistar rats under caloric restriction

AIMS

NAD-based therapeutic strategies are encouraged against obesity and heart disease. Our study, therefore, aimed to investigate the effects of nicotinamide riboside (NR), isolated or combined with caloric restriction (CR), both approaches well-known for stimulating NAD levels, on adiposity parameters, cardiometabolic factors and cardiac oxidative stress in rats submitted to cafeteria diet (CAF).

MAIN METHODS

After 42 days of CAF-induced obesity (hypercaloric and ultra-processed foods common to humans), we examined the effects of oral administration of NR (400 mg/kg for 28 days), combined or not with CR (-62% kcal, for 28 days), on anthropometric, metabolic, tissue, and cardiac oxidative stress parameters in obese male Wistar rats.

KEY FINDINGS

In obese rats, treatment with NR alone mitigated final body weight gain, reduced adiposity (visceral and subcutaneous), improved insulin resistance, and decreased TG/HDL ratio and heart size. In cardiac OS, treatment with NR increased the antioxidant capacity via glutathione peroxidase and catalase enzymes (in rats under CR) as well as reduced the pro-oxidant complex NADPH oxidase (in obese and lean rats). Hyperglycemia, hypertriglyceridemia and elevated levels of TBARS in the heart were state-dependent adverse effects, induced by treatment with NR.

SIGNIFICANCE

This is the first study to report effects of nicotinamide riboside on cardiac oxidative stress in an obesity model. Nicotinamide riboside, a natural dietary compound, presented antiobesity effects and cardiometabolic benefits, in addition to positively modulating oxidative stress in the heart, in a state-dependent manner.

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

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

Aqueous extract of pomegranate enriched in ellagitannins prevents anxiety-like behavior and metabolic changes induced by cafeteria diet in an animal model of menopause

Women around menopause are vulnerable to present psychiatric and metabolic disorders; thus, therapies that contribute to treat both pathologies are required. Previous reports showed that an aqueous extract of pomegranate (Punica granatum), enriched in ellagitannins, exerts an antidepressant-like effect in ovariectomized rats. We analyze whether this aqueous extract of P. granatum (AE-PG) prevents the anxiety-like behavior induced by a cafeteria diet (CAF) in middle-aged ovariectomized rats at the same time that it prevents an increase in body weight, glucose, lipids, and the changes on mRNA expression of the peroxisome proliferator-activated receptor-gamma (PPAR-γ) in the liver. Also, the effects of AE-PG on the protein levels of PPAR-γphospho-PPAR-γ, extracellular signal-regulated protein kinase (ERK1/2) and phospho-ERK1/2 were measured in the hippocampus and amygdala. CAF induced anxiety-like behavior, augmented lipids and glucose blood levels, body weight, visceral fat, insulin resistance, and decreased mRNA expression of PPAR-γ in the liver. In rats fed with the CAF, AE-PG prevented the anxiety-like behavior, reduced body weight, lowered lipid levels, reduced insulin resistance, and increased PPAR-γ mRNA expression in the liver. In the hippocampus, ERK1/2 but not PPAR-γ protein levels were decreased by CAF, while AE-PG prevented these effects. In the amygdala, CAF increased the phosphorylation of PPARγ, and AE-PG prevented it. In contrast, AE-PG rescued the decreased ERK1/2 protein level in the hippocampus caused by CAF. In conclusion, AE-PG treatment prevented anxiogenic and metabolic effects induced by CAF, and its effects appear to be mediated by ERK1/2 and PPARγ depending on the brain area studied.

Comparative Intracerebroventricular and Intrathecal Administration of a Nanomolar Macrocyclic Melanocortin Receptor Agonist MDE6-5-2c (c[Pro-His-DPhe-Arg-Trp-Dap-Ala-DPro]) Decreases Food Intake in Mice

There is a critical need to find safe therapeutics to treat an increasingly obese population and diseases associated with an imbalance in energy homeostasis. The melanocortin-3 receptor (MC3R) and melanocortin-4 receptor (MC4R) ligands have long been the focus to help scientists understand energy homeostasis and the regulation of feeding behavior. Herein, we use a nanomolar macrocyclic melanocortin receptor agonist ligand MDE6-5-2c (c[Pro-His-DPhe-Arg-Trp-Dap-Ala-DPro) to examine metabolic and energy hemostasis profiles upon intrathecal (IT) administration directly into the spinal cord as compared to intracerebroventricular (ICV) administration directly into the brain. Overall, central ICV administration of MDE6-5-2c resulted in decreased food intake, in a dose-dependent manner, and decreased respiratory exchange ratio (RER). Comparison of IT versus ICV routes of MDE6-5-2c administration resulted in MDE6-5-2c possessing a longer duration of action on both feeding behavior and RER via IT. The C-peptide, ghrelin, GIP, leptin, IL-6, and resistin plasma hormones and biomarkers were compared using IT versus ICV MDE6-5-2c routes of administration. Plasma resistin levels were decreased upon ICV treatment of MDE6-5-2c, as compared to ICV vehicle control treatment. Intrathecal treatment resulted in significantly decreased inflammatory cytokine interleukin-6 (IL-6) levels compared to ICV administration. Investigation of the nonselective MC3R and MC4R macrocyclic agonist MDE6-5-2c molecule revealed differences in food intake, RER, and plasma biomarker profiles based upon ICV or IT routes of administration and characterize this novel molecular chemotype as a molecular probe to study the melanocortin system in vivo.

Synergistic effects of low-level stress and a Western diet on metabolic homeostasis, mood, and myocardial ischemic tolerance

How low-level psychological stress and overnutrition interact in influencing cardiometabolic disease is unclear. Mechanistic overlaps suggest potential synergies; however, findings are contradictory. We test whether low-level stress and Western diet (WD) feeding synergistically influence homeostasis, mood, and myocardial ischemic tolerance. Male C57BL6/J mice were fed a control diet or WD (32%/57%/11% calories from fat/carbohydrates/protein) for 12 wk, with subgroups restrained for 30 min/day over the final 3 wk. Metabolism, behavior, tolerance of perfused hearts to ischemia-reperfusion (I/R), and cardiac “death proteins” were assessed. The WD resulted in insignificant trends toward increased body weight (+5%), glucose (+40%), insulin (+40%), triglycerides (+15%), and cholesterol (+20%) and reduced leptin (−20%) while significantly reducing insulin sensitivity [100% rise in homeostasis model assessment of insulin resistance (HOMA-IR), P < 0.05]. Restraint did not independently influence metabolism while increasing HOMA-IR a further 50% (and resulting in significant elevations in insulin and glucose to 60–90% above control) in WD mice ( P < 0.05), despite blunting weight gain in control and WD mice. Anxiogenesis with restraint or WD was nonadditive, whereas anhedonia (reduced sucrose consumption) only arose with their combination. Neuroinflammation markers (hippocampal TNF-α, Il-1b) were unchanged. Myocardial I/R tolerance was unaltered with stress or WD alone, whereas the combination worsened dysfunction and oncosis [lactate dehydrogenase (LDH) efflux]. Apoptosis (nucleosome accumulation) and death protein expression (BAK, BAX, BCL-2, RIP-1, TNF-α, cleaved caspase-3, and PARP) were unchanged. We conclude that mild, anxiogenic yet cardio-metabolically “benign” stress interacts synergistically with a WD to disrupt homeostasis, promote anhedonia (independently of neuroinflammation), and impair myocardial ischemic tolerance (independently of apoptosis and death protein levels).

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.

Biochemical and nutritional overview of diet-induced metabolic syndrome models in rats: what is the best choice?

Metabolic syndrome (MS) is a condition that includes obesity, insulin resistance, dyslipidemias among other, abnormalities that favors type 2 Diabetes Mellitus (T2DM) and cardiovascular diseases development. Three main diet-induced metabolic syndrome models in rats exist: High carbohydrate diet (HCHD), high fat diet (HFD), and high carbohydrate-high fat diet (HCHHFD). We analyzed data from at least 35 articles per diet, from different research groups, to determine their effect on the development of the MS, aimed to aid researchers in choosing the model that better suits their research question; and also the best parameter that defines obesity, as there is no consensus to determine this condition in rats. For the HCHD we found a mild effect on body weight gain and fasting blood glucose levels (FBG), but significant increases in triglycerides, fasting insulin, insulin resistance and visceral fat accumulation. HFD had the greater increase in the parameters previously mentioned, followed by HCHHFD, which had a modest effect on FBG levels. Therefore, to study early stages of MS a HCHD is recommended, while HFD and HCHHFD better reproduce more severe stages of MS. We recommend the assessment of visceral fat accumulation as a good estimate for obesity in the rat.

Cerebrocortical proteome profile of female rats subjected to the western diet and chronic social stress

The energy-dense western diet significantly increases the risk of obesity, type 2 diabetes, cardiovascular episodes, stroke, and cancer. Recently more attention has been paid to the contribution of an unhealthy lifestyle on the development of central nervous system disorders. Exposure to long-lasting stress is one of the key lifestyle modifications associated with the increased prevalence of obesity and metabolic diseases. The main goal of the present study was to verify the hypothesis that exposure to chronic stress modifies alterations in the brain proteome induced by the western diet. Female adult rats were fed with the prepared chow reproducing the human western diet and/or subjected to chronic stress induced by social instability for 6 weeks. A control group of lean rats were fed with a standard diet. Being fed with the western diet resulted in an obese phenotype and induced changes in the serum metabolic parameters. The combination of the western diet and chronic stress exposure induced more profound changes in the rat cerebrocortical proteome profile than each of these factors individually. The down-regulation of proteins involved in neurotransmitter secretion (Rph3a, Snap25, Syn1) as well as in learning and memory processes (Map1a, Snap25, Tnr) were identified, while increased expression was detected for 14-3-3 protein gamma (Ywhag) engaged in the modulation of the insulin-signaling cascade in the brain. An analysis of the rat brain proteome reveals important changes that indicate that a combination of the western diet and stress exposure may lead to impairments of neuronal function and signaling.

Cafeteria diet induces progressive changes in hypothalamic mechanisms involved in food intake control at different feeding periods in female rats

We studied the effects of cafeteria diet (CAF) intake from weaning on mRNA levels and DNA methylation state of feeding-related neuropeptides and hormone receptors in individual hypothalamic nuclei at different feeding periods. Four weeks of CAF (short-term) increased energy intake and adiposity, without affecting neuropeptides' expression. Eleven weeks of CAF (medium-term) increased energy intake, adiposity, leptinemia, and body weight, with an orexigenic response of the lateral hypothalamus, paraventricular and ventromedial nuclei, given by upregulation of Orexins, AgRP, and NPY opposed by an anorectic signal of the arcuate nucleus, which displayed a higher POMC expression. The changes in neuropeptidic mRNA levels were related to epigenetic modifications in their promoter regions. Metabolic and molecular changes were intensified after 20 weeks of diet (long-term). The alterations in these hypothalamic brain nuclei could add information about their differential role in food intake control, and how their action is disrupted during the development of obesity.

FoxO1 is a critical regulator of hepatocyte lipid deposition in chronic stress mice

Forkhead box O1 (FoxO1) is involved in lipid metabolisms. However, its role in chronic stress-related nonalcoholic fatty liver disease (NAFLD) is unclear. The scientific premise of our study was based on the finding that FoxO1 expression is increased in the liver of mice after chronic stress. It is important to understand the mechanisms involved in the activation of FoxO1 and how its function affects the liver lipid deposition. We employed a murine chronic stress model, in which mice were treated by plantar electrical stimulation and restraint for 6 weeks, and a cellular model, in which Hepa1–6 cells were treated with corticosterone. We also used a pharmacologic approach as1842856, a highly specific FoxO1 inhibitor. Lipid metabolism related genes levels were measured by qRT-PCR and the lipid levels by biochemical detection. We show that the level of FoxO1 is significantly elevated in the liver of chronic stress mice. Transcription factor FoxO1 regulates a lipid synthesis phenotype of hepatocyte that is involved in the development and progression of NAFLD. We have shown that inhibition of FoxO1 induced phenotypic conversion of hepatocytes and down-regulates lipid synthesis genes expression by hepatocytes, which contribute to lipid deposition in NAFLD. At the cellular level, the inhibitor of FoxO1 as1842856 can also attenuate the lipid deposition of Hepa1–6 cells induced by corticosterone. Targeting FoxO1 is a novel therapeutic target for chronic stress-related NAFLD.

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.

Transcranial direct current stimulation (tDCS) modulates biometric and inflammatory parameters and anxiety-like behavior in obese rats

Obesity is a multifactorial disease associated with metabolic dysfunction and the prevention and treatment of obesity are often unsatisfactory. Transcranial direct-current stimulation (tDCS) is a non-invasive brain stimulation technique that has proven promising in the treatment of eating disorders such as obesity. We investigate the effects of tDCS on locomotor and exploratory activities, anxiety-like and feeding behavior, and levels of brain-derived neurotrophic factor (BDNF), IL (interleukin)-10, IL-1β, and tumor necrosis factor-alpha (TNF-α) in the cerebral cortex of obese rats. A total of 40 adult male Wistar rats were used in our study. Animals were divided into groups of three or four animals per cage and allocated to four treatment groups: standard diet plus sham tDCS treatment (SDS), standard diet plus tDCS treatment (SDT), hypercaloric diet plus sham tDCS treatment (HDS), hypercaloric diet plus tDCS treatment (HDT). After 40 days on a hypercaloric diet and/or standard diet were to assessed the locomotor and exploratory activity and anxiety-like behavior to by the open field (OF) and elevated plus maze (EPM) tests respectively before and after exposure to tDCS treatment. The experimental groups were submitted to active or sham treatment tDCS during eight days. Palatable food consumption test (PFT) was performed 24 h after the last tDCS session under fasting and feeding conditions. Obese animals submitted to tDCS treatment showed a reduction in the Lee index, visceral adipose tissue weight, and food craving. In addition, bicephalic tDCS decreased the cerebral cortex levels of IL-1β and TNF-α in these animals. Exposure to a hypercaloric diet produced an anxiolytic effect, which was reversed by bicephalic tDCS treatment. These results suggest that, in accordance with studies in humans, bicephalic tDCS could modulate biometric and inflammatory parameters, as well as anxiety-like and feeding behavior, of rats subjected to the consumption of a hypercaloric diet.

The salivary levels of leptin and interleukin-6 as potential inflammatory markers in children obesity

Background

Obesity among children is an alarming issue due to an increased incidence over the last years with devastating physiological and psychological consequences. Current available medical diagnostic tools use invasive methods to evaluate and monitor the lipid profile, glycaemia or liver status for determining the overweight/ obesity complications. The standard methods proposed for the assay of IL6 and leptin from saliva cannot detect these two biomarkers in children saliva; the levels of IL6 and leptin in children’s saliva are lower than the limit of determination of the standard methods. Therefore, we proposed a method based on utilization of stochastic sensors, able to simultaneously perform a qualitative and quantitative determination of these two biomarkers within minutes, in the range able to cover healthy and obese children.

Methods

Children from the urban area monitored for annual standard analyses and health status assessment at National Institute of Endocrinology C.I. Parhon within University of Medicine and Pharmacy “Carol Davila”, Bucharest, Romania were included in the study. In the same day, for all participants of the study, blood analyses were performed and saliva samples were collected for the determination of the IL-6 and leptin levels.

Findings/ Results

The children diagnosed with overweight/ obesity presented not significantly different blood lipid profile and glycaemia comparing to the control group. Only few cases of the children presented high levels of cholesterol, low level of HDL-cholesterol, a slightly increased level of triglycerides and transaminases. No correlation with the body mass index could be established with the blood analyses results. In case of the overweight/obese children, the salivary level of the proinflammatory citokynes IL-6 (41ng/mL±21) and leptin (40.4ng/mL±28.8), were significantly increased comparing to normal weight children (IL-6 8.1±4.6, leptin 9.58±3.1). Moreover, the saliva level of the IL-6 was positively correlated with the body mass index. Salivary leptin level was highly variable in case of obese children, 6 patients presenting similar levels with the control group.

Conclusions

Increased levels of salivary IL-6 and leptin sustain a systemic inflammation status despite normal range of standard blood analyses. The results were positively correlated in case of IL-6 with the body mass index the general accepted method used for the assessment of the obesity or overweight degree The determination of these markers in saliva samples by a stochastic method proved the utility within the medical examination for a better evaluation of the health status in obesity. The method has some advantages like: easy collection of the biological sample, fast determination of low concentrations and could be promising in case of no associated oral cavity infections or inflammations which could interfere the results.

Involvement of glucocorticoid prereceptor metabolism and signaling in rat visceral adipose tissue lipid metabolism after chronic stress combined with high-fructose diet

Both fructose overconsumption and increased glucocorticoids secondary to chronic stress may contribute to overall dyslipidemia. In this study we specifically assessed the effects and interactions of dietary fructose and chronic stress on lipid metabolism in the visceral adipose tissue (VAT) of male Wistar rats. We analyzed the effects of 9-week 20% high fructose diet and 4-week chronic unpredictable stress, separately and in combination, on VAT histology, glucocorticoid prereceptor metabolism, glucocorticoid receptor subcellular redistribution and expression of major metabolic genes. Blood triglycerides and fatty acid composition were also measured to assess hepatic Δ9 desaturase activity. The results showed that fructose diet increased blood triglycerides and Δ9 desaturase activity. On the other hand, stress led to corticosterone elevation, glucocorticoid receptor activation and decrease in adipocyte size, while phosphoenolpyruvate carboxykinase, adipose tissue triglyceride lipase, FAT/CD36 and sterol regulatory element binding protein-1c (SREBP-1c) were increased, pointing to VAT lipolysis and glyceroneogenesis. The combination of stress and fructose diet was associated with marked stimulation of fatty acid synthase and acetyl-CoA carboxylase mRNA level and with increased 11β-hydroxysteroid dehydrogenase type 1 and hexose-6-phosphate dehydrogenase protein levels, suggesting a coordinated increase in hexose monophosphate shunt and de novo lipogenesis. It however did not influence the level of peroxisome proliferator-activated receptor-gamma, SREBP-1c and carbohydrate responsive element-binding protein. In conclusion, our results showed that only combination of dietary fructose and stress increase glucocorticoid prereceptor metabolism and stimulates lipogenic enzyme expression suggesting that interaction between stress and fructose may be instrumental in promoting VAT expansion and dysfunction.

Modulation of hepatic inflammation and energy-sensing pathways in the rat liver by high-fructose diet and chronic stress

PURPOSE

High-fructose consumption and chronic stress are both associated with metabolic inflammation and insulin resistance. Recently, disturbed activity of energy sensor AMP-activated protein kinase (AMPK) was recognized as mediator between nutrient-induced stress and inflammation. Thus, we analyzed the effects of high-fructose diet, alone or in combination with chronic stress, on glucose homeostasis, inflammation and expression of energy sensing proteins in the rat liver.

METHODS

In male Wistar rats exposed to 9-week 20% fructose diet and/or 4-week chronic unpredictable stress we measured plasma and hepatic corticosterone level, indicators of glucose homeostasis and lipid metabolism, hepatic inflammation (pro- and anti-inflammatory cytokine levels, Toll-like receptor 4, NLRP3, activation of NFκB, JNK and ERK pathways) and levels of energy-sensing proteins AMPK, SIRT1 and peroxisome proliferator-activated receptor gamma coactivator-1 alpha (PGC-1α).

RESULTS

High-fructose diet led to glucose intolerance, activation of NFκB and JNK pathways and increased intrahepatic IL-1β, TNFα and inhibitory phosphorylation of insulin receptor substrate 1 on Ser³⁰⁷. It also decreased phospho-AMPK/AMPK ratio and increased SIRT1 expression. Stress alone increased plasma and hepatic corticosterone but did not influence glucose tolerance, nor hepatic inflammatory or energy-sensing proteins. After the combined treatment, hepatic corticosterone was increased, glucose tolerance remained preserved, while hepatic inflammation was partially prevented despite decreased AMPK activity.

CONCLUSION

High-fructose diet resulted in glucose intolerance, hepatic inflammation, decreased AMPK activity and reduced insulin sensitivity. Chronic stress alone did not exert such effects, but when applied together with high-fructose diet it could partially prevent fructose-induced inflammation, presumably due to increased hepatic glucocorticoids.

High-fat diet effects on metabolic responses to chronic stress

CONTEXT

High-fat diets and chronic stress are prevalent risk factors for various chronic diseases in modern societies.

OBJECTIVE

This study investigated the effect of high-fat diet on glucose-related metabolic responses to chronic foot-shock stress.

MATERIALS AND METHODS

Male rats were divided into high-fat diet (containing 54.21% saturated and 44.89% unsaturated fatty acids) and normal diet groups and then into stress and non-stress subgroups. The diets were applied for 5 weeks, and stress was induced during the last week of the diet course. Plasma levels of metabolic parameters, HOMA-IR index, intra-abdominal fat weight, and islets' insulin secretion were assessed.

RESULTS

High-fat diet increased abdominal fat weight and plasma leptin, and insulin levels in response to stress without affecting HOMA-IR index and islets' insulin secretion.

CONCLUSIONS

High proportion of unsaturated fat may not lead to deleterious metabolic responses; however combined with chronic stress has a synergistic and adverse effect on visceral adiposity and results in elevated plasma leptin.

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.

Glucose intolerance after chronic stress is related with downregulated PPAR-γ in adipose tissue

Background

Chronic stress is associated with increased risk of glucose intolerance and cardiovascular diseases, albeit through undefined mechanisms. With the aim of gaining insights into the latter, this study examined the metabolic profile of young adult male rats that were exposed to chronic unpredictable stress.

Methods

Young adult male rats were submitted to 4 weeks of chronic unpredictable stress and allowed to recover for 5 weeks. An extensive analysis including of morphologic, biochemical and molecular parameters was carried out both after chronic unpredictable stress and after recovery from stress.

Results

After 28 days of chronic unpredictable stress (CUS) the animals submitted to this protocol displayed less weight gain than control animals. After 5 weeks of recovery the weight gain rebounded to similar values of controls. In addition, following CUS, fasting insulin levels were increased and were accompanied by signs of impaired glucose tolerance and elevated serum corticosteroid levels. This biochemical profile persisted into the post-stress recovery period, despite the restoration of baseline corticosteroid levels. The mRNA expression levels of peroxisome proliferator-activated receptor (PPAR)-γ and lipocalin-2 in white adipose tissue were, respectively, down- and up-regulated.

Conclusions

Reduction of PPAR-γ expression and generation of a pro-inflammatory environment by increased lipocalin-2 expression in white adipose tissue may contribute to stress-induced glucose intolerance.

Euterpe edulis Extract but Not Oil Enhances Antioxidant Defenses and Protects against Nonalcoholic Fatty Liver Disease Induced by a High-Fat Diet in Rats

We investigated the effects of E. edulis bioproducts (lyophilized pulp [LEE], defatted lyophilized pulp [LDEE], and oil [EO]) on nonalcoholic fatty liver disease (NAFLD) induced by a high-fat diet (HFD) in rats. All products were chemically analyzed. In vivo, 42 rats were equally randomized into seven groups receiving standard diet, HFD alone or combined with EO, LEE, or LDEE. After NAFLD induction, LEE, LDEE, or EO was added to the animals' diet for 4 weeks. LEE was rich in polyunsaturated fatty acids. From LEE degreasing, LDEE presented higher levels of anthocyanins and antioxidant capacity in vitro. Dietary intake of LEE and especially LDEE, but not EO, attenuated diet-induced NAFLD, reducing inflammatory infiltrate, steatosis, and lipid peroxidation in liver tissue. Although both E. edulis bioproducts were not hepatotoxic, only LDEE presented sufficient benefits to treat NAFLD in rats, possibly by its low lipid content and high amount of phenols and anthocyanins.

The Influence of Palatable Diets in Reward System Activation: A Mini Review

The changes in eating patterns that have occurred in recent decades are an important cause of obesity. Food intake and energy expenditure are controlled by a complex neural system involving the hypothalamic centers and peripheral satiety system (gastrointestinal and pancreatic hormones). Highly palatable and caloric food disrupts appetite regulation; however, palatable foods induce pleasure and reward. The cafeteria diet is such a palatable diet and has been shown consistently to increase body weight and induce hyperplasia in animal obesity models. Moreover, palatable high-fat foods (such as those of the cafeteria diet) can induce addiction-like deficits in brain reward function and are considered to be an important source of motivation that might drive overeating and contribute to the development of obesity. The mechanism of neural adaptation triggered by palatable foods is similar to those that have been reported for nondrug addictions and long-term drug use. Thus, this review attempts to describe the potential mechanisms that might lead to highly palatable diets, such as the cafeteria diet, triggering addiction, or compulsion through the reward system.

High Sucrose Intake Ameliorates the Accumulation of Hepatic Triacylglycerol Promoted by Restraint Stress in Young Rats

Non-alcoholic fatty liver disease (NAFLD) is the most common chronic liver disorder. Stress promotes the onset of the NAFLD with a concomitant increment in the activity of the hepatic 11β-hydroxysteroid dehydrogenase type 1 (11β-HSD-1). However, the interaction between the stress and a carbohydrate-enriched diet for the development of NAFLD in young animals is unknown. In the present study, we evaluated the impact of chronic stress on the hepatic triacylglycerol level of young rats fed or not with a high sucrose-diet. For doing this, 21-day old male Wistar rats were allocated into 4 groups: control (C), chronic restraint stress (St), high-sucrose diet (S30), and chronic restraint stress plus a 30 % sucrose diet (St + S30). Chronic restraint stress consisted of 1-hour daily session, 5 days per week and for 4 weeks. Rats were fed with a standard chow and tap water (C group) or 30 % sucrose diluted in water (S30 group). The St + S30 groups consumed less solid food but had an elevated visceral fat accumulation in comparison with the St group. The St group showed a high level of serum corticosterone and a high activity of the hepatic 11β-HSD-1 concomitantly to the augmentation of hepatic steatosis signs, a high hepatic triacylglycerol content, and hepatic oxidative stress. Conversely, the high-sucrose intake in stressed rats (St + S30 group) reduced the hepatic 11β-HSD-1 activity, the level of serum corticosterone, and the hepatic triacylglycerol content. Present findings show that a high-sucrose diet ameliorates the triacylglycerol accumulation in liver promoted by the restraint stress in young male rats.

Chronic stress associated with hypercaloric diet changes the hippocampal BDNF levels in male Wistar rats

Chronic stress, whether associated with obesity or not, leads to different neuroendocrine and psychological changes. Obesity or being overweight has become one of the most serious worldwide public health problems. Additionally, it is related to a substantial increase in daily energy intake, which results in substituting nutritionally adequate meals for snacks. This metabolic disorder can lead to morbidity, mortality, and reduced quality of life. On the other hand, brain-derived neurotrophic factor (BDNF) is widely expressed in all brain regions, particularly in the hypothalamus, where it has important effects on neuroprotection, synaptic plasticity, mammalian food intake-behavior, and energy metabolism. BDNF is involved in many activities modulated by the hypothalamic-pituitary-adrenal (HPA) axis. Therefore, this study aims to evaluate the effect of obesity associated with chronic stress on the BDNF central levels of rats. Obesity was controlled by analyzing the animals' caloric intake and changes in body weight. As a stress parameter, we analyzed the relative adrenal gland weight. We found that exposure to chronic restraint stress during 12 weeks increases the adrenal gland weight, decreases the BDNF levels in the hippocampus and is associated with a decrease in the calorie and sucrose intake, characterizing anhedonia. These effects can be related stress, a phenomenon that induces depression-like behavior. On the other hand, the rats that received the hypercaloric diet had an increase in calorie intake and became obese, which was associated with a decrease in hypothalamus BDNF levels.

Long-Term Over-Expression of Neuropeptide Y in Hypothalamic Paraventricular Nucleus Contributes to Adipose Tissue Insulin Resistance Partly via the Y5 Receptor

Intracerebroventricular injection and overexpression of Neuropeptide Y (NPY) in the paraventricular nucleus (PVN) has been shown to induce obesity and glucose metabolism disorder in rodents; however, the underlying mechanisms are still unclear. The aim of this study was to investigate the mechanism contributing to glucose metabolic disturbance induced by NPY. Recombinant lentiviral NPY vectors were injected into the PVN of rats fed a high fat (HFD) or low-fat diet. 8 weeks later, in vivo intravenous glucose tolerance tests and euglycemic-hyperinsulinemic clamp revealed that insulin resistance of adipose tissue were induced by NPY overexpression with or without HFD. NPY increased food intake, but did not change blood glucose, glycated hemoglobin A1c (HbA1c) or lipid levels. However, NPY decreased the expression of pGSK3β, PI3K p85 and pAKTSer473 in adipose tissue of rats. In vitro, 3T3-L1 adipocytes were treated with NPY, NPY Y1 and Y5 receptor antagonists. Glucose consumption and 2-deoxy-D-[3H] glucose uptake were partly inhibited by NPY, while a decrease in PI3K-AKT pathway signaling and a decreased expression of pGSK3α and pGSK3β were observed. Nevertheless, a Y5 receptor antagonist (L-152,804) reversed the effects of NPY on glucose uptake and consumption. These data suggest that long-term over-expression of NPY in PVN contributes to the establishment of adipose tissue insulin resistance, at least partly via the Y5 Receptor.

Physical training at sub-threshold intensity reduces the prevalence of hepatic steatosis after high-fat diet in rats

The purpose of the present study was to evaluate the effects of swimming physical training with sub-threshold load on the prevalence of hepatic steatosis in Wistar rats fed high-fat diets (cafeteria or baru). After 2 months of cafeteria diet administration, the rats were separated into 6 groups: Sedentary or Trained Baru diet; Sedentary or Trained Cafeteria diet; Sedentary or Trained standard diet. The trained groups were subjected to swimming exercise at sub-threshold intensity (2% of body weight) during 8 weeks, 5x/week, 1h/day. The body weight and hepatohistological changes were analyzed. Sedentary groups fed high-fat diets presented higher body weight gain when compared to control trained group. The swimming training at the proposed intensity was able to prevent the hepatic steatosis in rats fed high-fat diets.

Integrated circuits and molecular components for stress and feeding: implications for eating disorders

Eating disorders are complex brain disorders that afflict millions of individuals worldwide. The etiology of these diseases is not fully understood, but a growing body of literature suggests that stress and anxiety may play a critical role in their development. As our understanding of the genetic and environmental factors that contribute to disease in clinical populations like anorexia nervosa, bulimia nervosa and binge eating disorder continue to grow, neuroscientists are using animal models to understand the neurobiology of stress and feeding. We hypothesize that eating disorder clinical phenotypes may result from stress-induced maladaptive alterations in neural circuits that regulate feeding, and that these circuits can be neurochemically isolated using animal model of eating disorders.

Hypercaloric diet modulates effects of chronic stress: a behavioral and biometric study on rats

Obesity is a chronic disease that has been associated with chronic stress and hypercaloric diet (HD) consumption. Increased ingestion of food containing sugar and fat ingredients (comfort food) is proposed to "compensate" chronic stress effects. However, this eating habit may increase body fat depositions leading to obesity. This study evaluated behavioral/physiological parameters seeking to establish whether there is an association between the effects of HD intake and stress, and to test the hypothesis that the development of anxious behavior and obesity during chronic stress periods depends on the type of diet. Sixty-day-old male Wistar rats (n = 100) were divided into four groups: standard chow, hypercaloric diet, chronic stress/standard chow and chronic stress/hypercaloric diet. Chronic stress was induced by restraint stress exposure for 1 h/day, for 80 d. At the end of this period, rat behavior was evaluated using open-field and plus-maze tests. The results showed that HD alone increased weight gain and adipose deposition in subcutaneous and mesenteric areas. However, stress reduced weight gain and adipose tissue in these areas. HD also increased naso-anal length and concurrent stress prevented this. Behavioral data indicated that stress increased anxiety-like behaviors and comfort food reduced these anxiogenic effects; locomotor activity increased in rats fed with HD. Furthermore, HD decreased corticosterone levels and stress increased adrenal weight. The data indicate that when rats are given HD and experience chronic stress this association reduces the pro-obesogenic effects of HD, and decreases adrenocortical activity.

Obesity and chronic stress are able to desynchronize the temporal pattern of serum levels of leptin and triglycerides

Disruption of the circadian system can lead to metabolic dysfunction as a response to environmental alterations. This study assessed the effects of the association between obesity and chronic stress on the temporal pattern of serum levels of adipogenic markers and corticosterone in rats. We evaluated weekly weight, delta weight, Lee index, and weight fractions of adipose tissue (mesenteric, MAT; subcutaneous, SAT; and pericardial, PAT) to control for hypercaloric diet-induced obesity model efficacy. Wistar rats were divided into four groups: standard chow (C), hypercaloric diet (HD), stress plus standard chow (S), and stress plus hypercaloric diet (SHD), and analyzed at three time points: ZT0, ZT12, and ZT18. Stressed animals were subjected to chronic stress for 1h per day, 5 days per week, during 80 days. The chronic exposure to a hypercaloric diet was an effective model for the induction of obesity and metabolic syndrome, increasing delta weight, Lee index, weight fractions of adipose tissue, and triglycerides and leptin levels. We confirmed the presence of a temporal pattern in the release of triglycerides, corticosterone, leptin, and adiponectin in naïve animals. Chronic stress reduced delta weight, MAT weight, and levels of triglycerides, total cholesterol, and leptin. There were interactions between chronic stress and obesity and serum total cholesterol levels, between time points and obesity and adiponectin and corticosterone levels, and between time points and chronic stress and serum leptin levels. In conclusion, both parameters were able to desynchronize the temporal pattern of leptin and triglyceride release, which could contribute to the development of metabolic diseases such as obesity and metabolic syndrome.

6-Alkoxy-5-aryl-3-pyridinecarboxamides, a new series of bioavailable cannabinoid receptor type 1 (CB1) antagonists including peripherally selective compounds

We identified 6-alkoxy-5-aryl-3-pyridinecarboxamides as potent CB1 receptor antagonists with high selectivity over CB2 receptors. The series was optimized to reduce lipophilicity compared to rimonabant to achieve peripherally active molecules with minimal central effects. Several compounds that showed high plasma exposures in rats were evaluated in vivo to probe the contribution of central vs peripheral CB1 agonism to metabolic improvement. Both rimonabant and 14g, a potent brain penetrant CB1 receptor antagonist, significantly reduced the rate of body weight gain. However, 14h, a molecule with markedly reduced brain exposure, had no significant effect on body weight. PK studies confirmed similarly high exposure of both 14h and 14g in the periphery but 10-fold lower exposure in the brain for 14h. On the basis of these data, which are consistent with reported effects in tissue-specific CB1 receptor KO mice, we conclude that the metabolic benefits of CB1 receptor antagonists are primarily centrally mediated as originally believed.

Obesity may increase the occurrence of spontaneous periodontal disease in Wistar rats

OBJECTIVE

To evaluate the effect of body weight on the occurrence of spontaneous alveolar bone loss in Wistar rats.

METHODS

Twenty-eight rats were randomly divided in two groups. Control group received standardized rat chow diet and water. Test group received cafeteria (CAF) diet during 17 weeks. Diet was available for both groups ad libitum. Body weight and Lee Index were evaluated. At the end of the experimental period, rats were killed by decapitation and maxillae were defleshed with 9% sodium hypochlorite. Morphometric analysis was performed in digital standard photographs. Presence of spontaneous periodontitis was considered when mean alveolar bone loss was ≥0.51mm (75th percentile). Statistical analysis was performed with chi-square test, Mann-Whitney test and independent samples t-test (significance level P≤0.05).

RESULTS

After 17 weeks of exposure to standard CAF diet, a statistically significant mean difference in body weight (g±SD) (478±43 vs. 580±60) and Lee Index (3.07±0.05 vs. 3.24±0.07) was observed between control and obesity groups, respectively. Median (interquartile range) of alveolar bone loss in control group was 0.344 (0.313-0.367) and 0.491 (0.427-0.506) for buccal and palatal site, respectively. For obese group was 0.308 (0.289-0.354) and 0.549 (0.482-0.616) for buccal and palatal site, respectively. In animals submitted to CAF diet, 20 sites were classified as spontaneous periodontal disease, whereas in control animals, only 8 sites exhibited periodontal breakdown according cut-off point. A significant difference between groups was detected (P=0.009).

CONCLUSIONS

It may be concluded that obesity increases the occurrence of spontaneous periodontal disease in Wistar rats.