Cardiac dysfunction in sucrose-fed rats is associated with alterations of phospholamban phosphorylation and TNF-α levels.

INTRODUCTION: High sucrose intake is linked to cardiovascular disease, a major global cause of mortality worldwide. Calcium mishandling and inflammation play crucial roles in cardiac disease pathophysiology. OBJECTIVE: Evaluate if sucrose-induced obesity is related to deterioration of myocardial function due to alterations in the calcium-handling proteins in association with proinflammatory cytokines. METHODS: Wistar rats were divided into control and sucrose groups. Over eight weeks, Sucrose group received 30% sucrose water. Cardiac function was determined in vivo using echocardiography and in vitro using papillary muscle assay. Western blotting was used to detect calcium handling protein; ELISA assay was used to assess TNF-α and IL-6 levels. RESULTS: Sucrose led to cardiac dysfunction. RYR2, SERCA2, NCX, pPBL Ser16 and L-type calcium channels were unchanged. However, pPBL-Thr17, and TNF-α levels were elevated in the S group. CONCLUSION: Sucrose induced cardiac dysfunction and decreased myocardial contractility in association with altered pPBL-Thr17 and elevated cardiac pro-inflammatory TNF-α.

Neurolysin Knockout Mice in a Diet-Induced Obesity Model.

Neurolysin oligopeptidase (E.C.3.4.24.16; Nln), a member of the zinc metallopeptidase M3 family, was first identified in rat brain synaptic membranes hydrolyzing neurotensin at the Pro-Tyr peptide bond. The previous development of C57BL6/N mice with suppression of Nln gene expression (Nln-/-), demonstrated the biological relevance of this oligopeptidase for insulin signaling and glucose uptake. Here, several metabolic parameters were investigated in Nln-/- and wild-type C57BL6/N animals (WT; n = 5-8), male and female, fed either a standard (SD) or a hypercaloric diet (HD), for seven weeks. Higher food intake and body mass gain was observed for Nln-/- animals fed HD, compared to both male and female WT control animals fed HD. Leptin gene expression was higher in Nln-/- male and female animals fed HD, compared to WT controls. Both WT and Nln-/- females fed HD showed similar gene expression increase of dipeptidyl peptidase 4 (DPP4), a peptidase related to glucagon-like peptide-1 (GLP-1) metabolism. The present data suggest that Nln participates in the physiological mechanisms related to diet-induced obesity. Further studies will be necessary to better understand the molecular mechanism responsible for the higher body mass gain observed in Nln-/- animals fed HD.

Characterization of autochthonous lactobacilli from goat dairy products with probiotic potential for metabolic diseases.

The present study aimed to design functional fermented goat milk with probiotic potential for metabolic diseases. Thereby, autochthonous lactobacilli from goat dairy products that target improving the inflammatory, lipid, and glycemic profile were characterized. We designed fermented goat milk using Lactobacillus delbrueckii subsp. indicus CRL1447 as starter strain, supplemented with different probiotic consortia formed by Limosilactobacillus fermentum CRL1446, Lactiplantibacillus paraplantarum CRL1449, and CRL1472 strains. These lactobacilli were selected for their positive effects on inhibition of α-glucosidase, bile salts hydrolase activity, cholesterol assimilation, and decreased triglyceride percentage in Caenorhabditis elegans. Furthermore, the lactobacilli oral administration to obese mice caused a significant decrease in body weight gain and ameliorated hyperglycemia and hyperlipemia. These results reveal the potential of this goat dairy product as a functional food to prevent obesity and related pathologies. Goat milk-derived products stand out for their marketing potential. Hence, fermented goat milk incorporating novel probiotics represents a group of food products with broad prospects by their promising nutritive and therapeutic properties for metabolic diseases. The goat dairy product designed in this study could be used in the prevention of dyslipidemia and hyperglycemia in obese people.

Blueberry Consumption and Changes in Obesity and Diabetes Mellitus Outcomes: A Systematic Review.

Low-grade inflammation and oxidative stress are key mechanisms involved in obesity and related disorders. Polyphenols from blueberry (BB) and bilberries (BiB) might protect against oxidative damage and inflammation. To summarize the effects of BiB or BB consumption in parameters related to obesity and its comorbidities, a search of the literature was performed in PubMed, Embase, and Cochrane Library repositories to identify all studies that evaluated associations of whole BB or BiB with obesity and associated disorders. Thirty-one studies were eligible for inclusion in this review: eight clinical trials and 23 animal studies. In humans, BB consumption only consistently decreased oxidative stress and improved endothelial function. In rodents, BB or BiB consumption caused positive effects on glucose tolerance, nuclear factor-kappa B (Nf-κb) activity, oxidative stress, and triglyceride (TG) content in the liver and hepatic steatosis. The high content of anthocyanins present in BB and BiB seems to attenuate oxidative stress. The decrease in oxidative stress may have a positive impact on glucose tolerance and endothelial function. Moreover, in rodents, these berries seem to protect against hepatic steatosis, through the decreased accumulation of hepatic TGs. BB and BiB might also attenuate inflammation by decreasing Nf-κb activity and immune cell recruitment into the adipose tissue.

Hepatic mitochondria in diet-induced obese mice (stereology and molecular analysis) / Mitocondrias hepáticas en ratones obesos inducidos por la dieta (estereología y análisis molecular)

SUMMARY: The world population is going through an obesity epidemic that has severe consequences for the health system. This study focused on studying hepatic mitochondria in obese animals induced by a high-fat (HF) diet and used the model-based stereology in electron micrographs for the quantitative study. Besides, the gene expressions of molecular markers of mitochondrial biogenesis carnitine palmitoyltransferase 1a (Cpt 1α), mitochondrial transcription factor a (Tfam), uncoupling protein 3 (Ucp 3), and nuclear respiratory factor 1 (Nrf 1) were analyzed. The HF diet caused a weight gain of +1820 % comparing the control group (C) with the HF group (from 0.32±0.31 g to 5.5±0.39 g, P<0.001). The HF group showed fat droplets in the hepatocyte cytoplasm (steatosis) and less dense and large mitochondria in transmission electron microscopy. The mitochondria size (cross-section) did not show a significant difference between the groups C and HF. However, the mitochondria numerical density per area was 30 % less, the mitochondrial surface density (outer membrane) was 20 % less, and the mitochondrial volume density was 22 % less in the HF group than the C group. The gene expressions of molecular markers of mitochondrial biogenesis Cpt 1α, Tfam, Ucp 3, and Nrf 1 decreased in the HF group compared to the C group. The quantitative results match perfectly with the molecular ones of mitochondrial biogenesis markers. In the future, it will be crucial to verify if and how these data recover with the reduction of obesity, which would be of significant interest given the current obesity epidemic that affects the world population.

RESUMEN: La población mundial atraviesa una epidemia de obesidad que tiene graves consecuencias para el sistema de salud. Este estudio se centró en el análisis de las mitocondrias hepáticas en animales obesos inducidos por una dieta alta en grasas (HF) y utilizó la estereología basada en modelos en micrografías electrónicas para el estudio cuantitativo. Además, se analizaron las expresiones génicas de los marcadores moleculares de la biogénesis mitocondrial carnitina palmitoiltransferasa 1a (Cpt 1α), factor de transcripción mitocondrial a (Tfam), proteína desacoplante 3 (Ucp 3) y factor respiratorio nuclear 1 (Nrf 1). La dieta HF provocó un aumento de peso de +1820 % comparando el grupo de control (C) con el grupo HF (de 0,32 ± 0,31 g a 5,5 ± 0,39 g, P <0,001). El grupo HF mostró gotas de grasa en el citoplasma de los hepatocitos (esteatosis) y mitocondrias menos densas y grandes en la microscopía electrónica de transmisión. El tamaño de las mitocondrias (sección transversal) no mostró una diferencia significativa entre los grupos C y HF. Sin embargo, la densidad numérica de mitocondrias por área fue 30% menor, la densidad de superficie mitocondrial (membrana externa) fue 20 % menor y la densidad de volumen mitocondrial fue 22 % menor en el grupo HF que en el grupo C. Las expresiones génicas de los marcadores moleculares de la biogénesis mitocondrial Cpt 1α, Tfam, Ucp 3 y Nrf 1 disminuyeron en el grupo HF en comparación con el grupo C. Los resultados cuantitativos coinciden perfectamente con los moleculares de los marcadores de biogénesis mitocondrial. En el futuro, será crucial verificar si estos datos se recuperan y cómo se recuperan con la reducción de la obesidad, lo que sería de gran interés dada la actual epidemia de obesidad que afecta a la población mundial.

Fasting and refeeding cycles alter subcutaneous white depot growth dynamics and the morphology of brown adipose tissue in female rats.

Intermittent food restriction (IFR) is used mainly for weight loss; however, its effects on adipose tissue are not known when alternating with an obesogenic diet. To demonstrate its effects on morphological dynamics of fat deposits, female Wistar rats were distributed into groups: standard control (ST-C), with commercial diet; DIO control (DIO-C), with a diet that induces obesity (DIO) during the first and last 15 d, replaced by a standard diet for thirty intermediate days; standard restricted (ST-R), with standard diet during the first and last 15 d, with six cycles of IFR at 50 % of ST-C; and DIO restricted (DIO-R), in DIO during the first and last 15 d, with six cycles of IFR at 50 % of DIO-C. At 105 d of life, white adipose tissue (WAT) and brown adipose tissue (BAT) deposits were collected, weighed and histology performed. The DIO-R group showed higher total food intake (DIO-R 10 768·0 (SEM 357·52) kJ/g v. DIO-C 8868·6 (SEM 249·25) kJ/g, P < 0·0001), energy efficiency during RAI (DIO-R 2·26 (SEM 0·05) g/kJ v. DIO-C 0·70 (SEM 0·03) g/kJ, P < 0·0001) and WAT (DIO-R 5·65 (SEM 0·30) g/100 g v. DIO-C 4·56 (SEM 0·30) g/100 g) than their respective control. Furthermore, IFR groups presented hypertrophy of WAT and BAT, as well as fibrosis in BAT. Thus, IFR can establish prospective resistance to weight loss by favouring changes in adipose tissue morphology, increased energy intake and efficiency. Finally, the DIO diet before and after IFR aggravates the damages caused by the restriction.

Oxidative stress and neuroinflammation in a rat model of co-morbid obesity and psychogenic stress.

BACKGROUND: There is growing recognition for a reciprocal, bidirectional link between anxiety disorders and obesity. Although the mechanisms linking obesity and anxiety remain speculative, this bidirectionality suggests shared pathophysiological processes. Neuroinflammation and oxidative damage are implicated in both pathological anxiety and obesity. This study investigates the relative contribution of comorbid diet-induced obesity and stress-induced anxiety to neuroinflammation and oxidative stress. METHODS: Thirty-six (36) male Lewis rats were divided into four groups based on diet type and stress exposure: 1) control diet unexposed (CDU) and 2) exposed (CDE), 3) Western-like high-saturated fat diet unexposed (WDU) and 4) exposed (WDE). Neurobehavioral tests were performed to assess anxiety-like behaviors. The catalytic concentrations of glutathione peroxidase and reductase were measured from plasma samples, and neuroinflammatory/oxidative stress biomarkers were measured from brain samples using Western blot. Correlations between behavioral phenotypes and biomarkers were assessed with Pearson's correlation procedures. RESULTS: We found that WDE rats exhibited markedly increased levels of glial fibrillary acidic protein (185 %), catalase protein (215 %), and glutathione reductase (GSHR) enzymatic activity (418 %) relative to CDU rats. Interestingly, the brain protein levels of glutathione peroxidase (GPx) and catalase were positively associated with body weight and behavioral indices of anxiety. CONCLUSIONS: Together, our results support a role for neuroinflammation and oxidative stress in heightened emotional reactivity to obesogenic environments and psychogenic stress. Uncovering adaptive responses to obesogenic environments characterized by high access to high-saturated fat/high-sugar diets and toxic stress has the potential to strongly impact how we treat psychiatric disorders in at-risk populations.

A novel nitroalkene vitamin E analogue inhibits the NLRP3 inflammasome and protects against inflammation and glucose intolerance triggered by obesity.

Chronic metabolic diseases, like obesity, type II diabetes and atherosclerosis often involve a low-grade and sterile systemic inflammatory state, in which activation of the pro-inflammatory transcription factor NF-kB and the NLRP3 inflammasome play a major role. It is well established that genetic inhibition of the NLRP3 inflammasome ameliorates acute and chronic inflammation. Indeed, accumulating experimental evidences in murine models and also in humans suggest that inhibition of the NLRP3 inflammasome might be a suitable approach to tackle the deleterious effects of chronic metabolic diseases. In this work, we explored our previously synthesized nitroalkene-Trolox™ derivative named NATx0, as a non-conventional anti-inflammatory strategy to treat chronic inflammatory diseases, such as obesity-induced glucose intolerance. We found that NATx0 inhibited NF-kB nuclear translocation and pro-inflammatory gene expression in macrophages in vitro. In addition, treatment with NATx0 prevented NLRP3 inflammasome activation after LPS/ATP stimulation in macrophages in vitro. When tested acutely in vivo, NATx0 inhibited neutrophil recruitment in zebrafish larvae, and also diminished IL-1ß production after LPS challenge in mice. Finally, when NATx0 was administered chronically to diet-induced obese mice, it decreased muscle tissue inflammation and glucose intolerance, leading to improved glucose homeostasis. In conclusion, we propose that this novel nitroalkene-Trolox derivative is a suitable tool to tackle acute and chronic inflammation in vitro and in vivo mainly due to inhibition of NF-kB/NLRP3 activation.

Caloric restriction recovers impaired ß-cell-ß-cell gap junction coupling, calcium oscillation coordination, and insulin secretion in prediabetic mice.

Caloric restriction can decrease the incidence of metabolic diseases, such as obesity and Type 2 diabetes mellitus. The mechanisms underlying the benefits of caloric restriction involved in insulin secretion and glucose homeostasis are not fully understood. Intercellular communication within the islets of Langerhans, mediated by Connexin36 (Cx36) gap junctions, regulates insulin secretion dynamics and glucose homeostasis. The goal of this study was to determine whether caloric restriction can protect against decreases in Cx36 gap junction coupling and altered islet function induced in models of obesity and prediabetes. C57BL6 mice were fed with a high-fat diet (HFD), showing indications of prediabetes after 2 mo, including weight gain, insulin resistance, and elevated fasting glucose and insulin levels. Subsequently, mice were submitted to 1 mo of 40% caloric restriction (2 g/day of HFD). Mice under 40% caloric restriction showed reversal in weight gain and recovered insulin sensitivity, fasting glucose, and insulin levels. In islets of mice fed the HFD, caloric restriction protected against obesity-induced decreases in gap junction coupling and preserved glucose-stimulated calcium signaling, including Ca2+ oscillation coordination and oscillation amplitude. Caloric restriction also promoted a slight increase in glucose metabolism, as measured by increased NAD(P)H autofluorescence, as well as recovering glucose-stimulated insulin secretion. We conclude that declines in Cx36 gap junction coupling that occur in obesity can be completely recovered by caloric restriction and obesity reversal, improving Ca2+ dynamics and insulin secretion regulation. This suggests a critical role for caloric restriction in the context of obesity to prevent islet dysfunction.

Effects of selenium supplementation on diet-induced obesity in mice with a disruption of the selenocysteine lyase gene.

BACKGROUND: The amino acid selenocysteine (Sec) is an integral part of selenoproteins, a class of proteins mostly involved in strong redox reactions. The enzyme Sec lyase (SCLY) decomposes Sec into selenide allowing for the recycling of the selenium (Se) atom via the selenoprotein synthesis machinery. We previously demonstrated that disruption of the Scly gene (Scly KO) in mice leads to the development of obesity and metabolic syndrome, with effects on glucose homeostasis, worsened by Se deficiency or a high-fat diet, and exacerbated in male mice. Our objective was to determine whether Se supplementation could ameliorate obesity and restore glucose homeostasis in the Scly KO mice. METHODS: Three-weeks old male and female Scly KO mice were fed in separate experiments a diet containing 45 % kcal fat and either sodium selenite or a mixture of sodium selenite and selenomethionine (selenite/SeMet) at moderate (0.25 ppm) or high (0.5-1 ppm) levels for 9 weeks, and assessed for metabolic parameters, oxidative stress and expression of selenoproteins. RESULTS: Se supplementation was unable to prevent obesity and elevated epididymal white adipose tissue weights in male Scly KO mice. Serum glutathione peroxidase activity in Scly KO mice was unchanged regardless of sex or dietary Se intake; however, supplementation with a mixture of selenite/SeMet improved oxidative stress biomarkers in the male Scly KO mice. CONCLUSION: These results unveil sex- and selenocompound-specific regulation of energy metabolism after the loss of Scly, pointing to a role of this enzyme in the control of whole-body energy metabolism regardless of Se levels.

Modulation of cardiac renin-angiotensin system, redox status and inflammatory profile by different volumes of aerobic exercise training in obese rats.

Overactivation of the classical arm of the renin-angiotensin (Ang) system (RAS) occurs during inflammation, oxidative stress and obesity-induced cardiomyopathy. The activation of the protective arm of RAS may act to counterbalance the deleterious effects of the classical RAS. Although aerobic exercise training (AET) shifts the balance of the RAS towards the protective arm, little is known about the molecular adaptations to different volumes of AET. The aim of this study was to evaluate the impact of AET volume on the modulation of RAS, as well as on cardiac biomarkers of oxidative stress and inflammation, in a diet-induced obesity model. Male Wistar rats were fed either control (CON) or high fat (HF) diet for 32 weeks. At week 20, HF group was subdivided into sedentary, low (LEV, 150 min/week) or high (HEV, 300 min/week) exercise volume. After 12 weeks of exercise, body mass gain, systolic blood pressure and heart rate were evaluated, as well as RAS, oxidative stress and inflammation in the heart. Body mass gain, systolic blood pressure and heart rate were higher in HF group when compared with SC group. Both trained groups restored systolic blood pressure and heart rate, but only HEV reduced body mass gain. Regarding the cardiac RAS, the HF group exhibited favoring of the classical arm and both trained groups shifted the balance towards the counterregulatory protective arm. The HF group had higher B1R expression and lower B2R expression than the control group, and B2R expression was reverted in both trained groups. The HF group also presented oxidative stress. The LEV and HEV groups improved the cardiac redox status by reducing Nox 2 and nitrotyrosine expression, but only the LEV group was able to increase the antioxidant defense by increasing Nrf2 signaling. While the HF group presented higher TNF-α, IL-6 and NFκB expression, and lower IL-10 expression, than the SC group, both training protocols improved the inflammatory profile. Although both trained groups improved the deleterious changes related to obesity cardiomyopathy, it is clear that the molecular mechanisms differ between them. Our results suggest that different exercise volumes might reach different molecular targets, and this could be a relevant factor when using exercise to manage obesity.

Polyphenol-rich green tea extract induces thermogenesis in mice by a mechanism dependent on adiponectin signaling.

Adiponectin is downregulated in obesity negatively impacting the thermogenesis and impairing white fat browning. Despite the notable effects of green tea (GT) extract in the enhancement of thermogenesis, if its effects are being mediated by adiponectin has been scarcely explored. For this purpose, we investigated the role of adiponectin in the thermogenic actions of GT extract by using an adiponectin-knockout mice model. Male wild-type (WT) and knockout (AdipoKO) C57Bl/6 mice (3 months) were divided into 6 groups: mice fed a standard diet+gavage with water (SD WT, and SD AdipoKO), high-fat diet (HFD)+gavage with water (HFD WT, and HFD AdipoKO), and HFD + gavage with 500 mg/kg of body weight (BW) of GT extract (HFD + GT WT, and HFD + GT AdipoKO). After 20 weeks of experimentation, mice were euthanized and adipose tissue was properly removed. Our findings indicate that treatment with GT extract reversed complications of obesity in WT mice by decreasing final BW gain, adiposity index, adipocyte size and insulin resistance (IR). However, the action of the GT extract was not effective in reversing those markers in the AdipoKO mice, although GT acts independently in the reversal of IR. GT-treatment induced enhancement in energy expenditure (EE), BAT thermogenesis, and promoted browning phenotype in the subcutaneous WAT (scWAT) of WT mice. On the other hand, the thermogenic program was markedly impaired in BAT and scWAT of AdipoKO mice. Our outcomes unveiled adiponectin as a key direct signal for GT extract inducing adaptive thermogenesis and browning in scWAT.

The Relevance of Thimet Oligopeptidase in the Regulation of Energy Metabolism and Diet-Induced Obesity.

Thimet oligopeptidase (EC 3.4.24.15; EP24.15; THOP1) is a potential therapeutic target, as it plays key biological functions in processing biologically functional peptides. The structural conformation of THOP1 provides a unique restriction regarding substrate size, in that it only hydrolyzes peptides (optimally, those ranging from eight to 12 amino acids) and not proteins. The proteasome activity of hydrolyzing proteins releases a large number of intracellular peptides, providing THOP1 substrates within cells. The present study aimed to investigate the possible function of THOP1 in the development of diet-induced obesity (DIO) and insulin resistance by utilizing a murine model of hyperlipidic DIO with both C57BL6 wild-type (WT) and THOP1 null (THOP1-/-) mice. After 24 weeks of being fed a hyperlipidic diet (HD), THOP1-/- and WT mice ingested similar chow and calories; however, the THOP1-/- mice gained 75% less body weight and showed neither insulin resistance nor non-alcoholic fatty liver steatosis when compared to WT mice. THOP1-/- mice had increased adrenergic-stimulated adipose tissue lipolysis as well as a balanced level of expression of genes and microRNAs associated with energy metabolism, adipogenesis, or inflammation. Altogether, these differences converge to a healthy phenotype of THOP1-/- fed a HD. The molecular mechanism that links THOP1 to energy metabolism is suggested herein to involve intracellular peptides, of which the relative levels were identified to change in the adipose tissue of WT and THOP1-/- mice. Intracellular peptides were observed by molecular modeling to interact with both pre-miR-143 and pre-miR-222, suggesting a possible novel regulatory mechanism for gene expression. Therefore, we successfully demonstrated the previously unanticipated relevance of THOP1 in energy metabolism regulation. It was suggested that intracellular peptides were responsible for mediating the phenotypic differences that are described herein by a yet unknown mechanism of action.

Colonic neuronal loss and delayed motility induced by high-fat diet occur independently of changes in the major groups of microbiota in Swiss mice.

BACKGROUND: Obesity has been linked to gastrointestinal disorders, and the loss of myenteric neurons in the intestine caused by high-fat diets (HFD) has been attributed to changes in microbiota and lipotoxicity. We investigated whether the prebiotic inulin modulates bacterial populations and alleviates neuronal loss in mice fed HFD. METHODS: Swiss mice were fed purified rodent diet or HFD (59% kcal fat), or both diets supplemented with inulin for 17 weeks. Intestinal motility was assessed and a metagenome analysis of the colonic microbiota was performed. The gene expression of inflammatory markers was evaluated, and immunofluorescence was performed for different types of myenteric neurons and glial cells in the distal colon. KEY RESULTS: The HFD caused obesity and delayed colonic motility. The loss of myenteric neurons and glial cells in obese mice affected all of the studied neuronal populations, including neurons positive for myosin-V, neuronal nitric oxide synthase, vasoactive intestinal peptide, and calretinin. Although obese mice supplemented with inulin exhibited improvements in colonic motility, neuronal, and glial cell loss persisted. The HFD did not altered the expression levels of inflammatory cytokines in the intestine or the prevalence of the major groups in microbiota, but inulin increased the proportion of the genus Akkermansia in the obese mice. CONCLUSIONS AND INFERENCES: In Swiss mice, the HFD-induced neuronal loss but did not change the major groups in microbiota. This suggests that, despite the increase in the beneficial bacteria, other factors that are directly linked to excess dietary lipid intake affect the enteric nervous system.

Food Selection of Cafeteria Diet Affects Memory Dysfunction Related to Obesity.

Cafeteria diet (CAF) mimics human Western diet and has been used in animal models to study obesity. The purpose of this study is to demonstrate that our CAF model induces metabolic disorder related to obesity and affects recognition memory in Wistar rats. We also compared the intake of two different soft drinks, as part of the CAF, on recognition memory. Our results demonstrate that CAF-fed rats increased weight gain and visceral adiposity, and exhibited hyperglycemia, hypertriglyceridemia, high leptin and low insulin plasma levels. Moreover, CAF animals showed higher lipid peroxidation in the liver and developed non-alcoholic fatty liver disease. Surprisingly, the group fed with cola-based soft drinks presented an improvement in recognition memory, whereas animals fed with orange-based soft drinks showed worse performance in this task. Our data indicates that CAF induces obesity and affects recognition memory, but the composition of the diet interfere when the neurological function is evaluated.

Leptin resensitisation: a reversion of leptin-resistant states.

Leptin resistance refers to states in which leptin fails to promote its anticipated effects, frequently coexisting with hyperleptinaemia. Leptin resistance is closely associated with obesity and also observed in physiological situations such as pregnancy and in seasonal animals. Leptin resensitisation refers to the reversion of leptin-resistant states and is associated with improvement in endocrine and metabolic disturbances commonly observed in obesity and a sustained decrease of plasma leptin levels, possibly below a critical threshold level. In obesity, leptin resensitisation can be achieved with treatments that reduce body adiposity and leptinaemia, or with some pharmacological compounds, while physiological leptin resistance reverts spontaneously. The restoration of leptin sensitivity could be a useful strategy to treat obesity, maintain weight loss and/or reduce the recidivism rate for weight regain after dieting. This review provides an update and discussion about reversion of leptin-resistant states and modulation of the molecular mechanisms involved in each situation.

Guarana supplementation attenuated obesity, insulin resistance, and adipokines dysregulation induced by a standardized human Western diet via brown adipose tissue activation.

Obesity is a metabolic disorder associated with adverse health consequences that has increased worldwide at an epidemic rate. This has encouraged many people to utilize nonprescription herbal supplements for weight loss without knowledge of their safety or efficacy. However, mounting evidence has shown that some herbal supplements used for weight loss are associated with adverse effects. Guarana seed powder is a popular nonprescription dietary herb supplement marketed for weight loss, but no study has demonstrated its efficacy or safety when administered alone. Wistar rats were fed four different diets (low-fat diet and Western diet with or without guarana supplementation) for 18 weeks. Metabolic parameters, gut microbiota changes, and toxicity were then characterized. Guarana seed powder supplementation prevented weight gain, insulin resistance, and adipokine dysregulation induced by Western diet compared with the control diet. Guarana induced brown adipose tissue expansion, mitochondrial biogenesis, uncoupling protein-1 overexpression, AMPK activation, and minor changes in gut microbiota. Molecular docking suggested a direct activation of AMPK by four guarana compounds tested here. We propose that brown adipose tissue activation is one of the action mechanisms involved in guarana supplementation-induced weight loss and that direct AMPK activation may underlie this mechanism. In summary, guarana is an attractive potential therapeutic agent to treat obesity.

Microencapsulated feruloyl esterase-producing lactobacilli ameliorate lipid profile and glycaemia in high fat diet-induced obese mice.

The effect of oral administration of spray-dried microcapsules of feruloyl esterase (FE) producing Lactobacillus fermentum CRL1446 (Lf) and Lactobacillus johnsonii CRL1231 (Lj) on high fat diet-induced obese mice was investigated to evaluate whether these strains could be used as a biotherapeutic for obesity. Swiss albino mice were divided into a normal diet fed group receiving empty microcapsules (control), a high fat diet plus empty microcapsules (HFD group), HFD plus microcapsules with Lf (HFD-Lf group) and HDF plus microcapsules with Lj (HFD-Lj group). Microcapsules containing Lf or Lj at a dose of ~107 cells/day/mouse were given orally for 7 weeks. Body weight gain, adiposity index, plasma leptin, lipid profiles, glycaemia, insulinemia, oral glucose tolerance, intestinal FE, glutathione peroxidase and glutathione reductase (GR) activities were determined. Administration of lactobacilli (HFD-Lf and HFD-Lj groups) improved metabolic parameters (triglyceride, total cholesterol, low-density lipoprotein cholesterol levels) and cardiovascular risk indicators (37-46% decrease of atherogenic index), and reduced body weight gain (29-38%), adiposity index (42-62%), plasma leptin levels, liver weight and fat deposition in liver. Intestinal FE activities significantly increased in HFD-Lf (62%) and HFD-Lj group (48%), thus improving hepatic GR activity (42% increment) compared to HFD group. Moreover, L. johnsonii increased HDL-cholesterol and L. fermentum reduced blood glucose to levels similar to the control. These FE-producing lactobacilli have the potential to improve biomarkers involved in obesity by increasing intestinal FE activity.

Decrement in resting and insulin-stimulated soleus muscle mitochondrial respiration is an early event in diet-induced obesity in mice.

NEW FINDINGS: What is the central question of this study? What are the temporal responses of mitochondrial respiration and mitochondrial responsivity to insulin in soleus muscle fibres from mice during the development of obesity and insulin resistance? What is the main finding and its importance? Short- and long-term feeding with a high-fat diet markedly reduced soleus mitochondrial respiration and mitochondrial responsivity to insulin before any change in glycogen synthesis. Muscle glycogen synthesis and whole-body insulin resistance were present after 14 and 28 days, respectively. Our findings highlight the plasticity of mitochondria during the development of obesity and insulin resistance. ABSTRACT: Recently, significant attention has been given to the role of muscle mitochondrial function in the development of insulin resistance associated with obesity. Our aim was to investigate temporal alterations in mitochondrial respiration, H2 O2 emission and mitochondrial responsivity to insulin in permeabilized skeletal muscle fibres during the development of obesity in mice. Male Swiss mice (5-6 weeks old) were fed with a high-fat diet (60% calories from fat) or standard diet for 7, 14 or 28 days to induce obesity and insulin resistance. Diet-induced obese (DIO) mice presented with reduced glucose tolerance and hyperinsulinaemia after 7 days of high-fat diet. After 14 days, the expected increase in muscle glycogen content after systemic injection of glucose and insulin was not observed in DIO mice. At 28 days, blood glucose decay after insulin injection was significantly impaired. Complex I (pyruvate + malate) and II (succinate)-linked respiration and oxidative phosphorylation (ADP) were decreased after 7 days of high-fat diet and remained low in DIO mice after 14 and 28 days of treatment. Moreover, mitochondria from DIO mice were incapable of increasing respiratory coupling and ADP responsivity after insulin stimulation in all observed periods. Markers of mitochondrial content were reduced only after 28 days of treatment. The mitochondrial H2 O2 emission profile varied during the time course of DIO, with a reduction of H2 O2 emission in the early stages of DIO and an increased emission after 28 days of treatment. Our data demonstrate that DIO promotes transitory alterations in mitochondrial physiology during the early and late stages of insulin resistance related to obesity.

Maternal overnutrition by hypercaloric diets programs hypothalamic mitochondrial fusion and metabolic dysfunction in rat male offspring.

BACKGROUND: Maternal overnutrition including pre-pregnancy, pregnancy and lactation promotes a lipotoxic insult leading to metabolic dysfunction in offspring. Diet-induced obesity models (DIO) show that changes in hypothalamic mitochondria fusion and fission dynamics modulate metabolic dysfunction. Using three selective diet formula including a High fat diet (HFD), Cafeteria (CAF) and High Sugar Diet (HSD), we hypothesized that maternal diets exposure program leads to selective changes in hypothalamic mitochondria fusion and fission dynamics in male offspring leading to metabolic dysfunction which is exacerbated by a second exposure after weaning. METHODS: We exposed female Wistar rats to nutritional programming including Chow, HFD, CAF, or HSD for 9 weeks (pre-mating, mating, pregnancy and lactation) or to the same diets to offspring after weaning. We determined body weight, food intake and metabolic parameters in the offspring from 21 to 60 days old. Hypothalamus was dissected at 60 days old to determine mitochondria-ER interaction markers by mRNA expression and western blot and morphology by transmission electron microscopy (TEM). Mitochondrial-ER function was analyzed by confocal microscopy using hypothalamic cell line mHypoA-CLU192. RESULTS: Maternal programming by HFD and CAF leads to failure in glucose, leptin and insulin sensitivity and fat accumulation. Additionally, HFD and CAF programming promote mitochondrial fusion by increasing the expression of MFN2 and decreasing DRP1, respectively. Further, TEM analysis confirms that CAF exposure after programing leads to an increase in mitochondria fusion and enhanced mitochondrial-ER interaction, which partially correlates with metabolic dysfunction and fat accumulation in the HFD and CAF groups. Finally, we identified that lipotoxic palmitic acid stimulus in hypothalamic cells increases Ca2+ overload into mitochondria matrix leading to mitochondrial dysfunction. CONCLUSIONS: We concluded that maternal programming by HFD induces hypothalamic mitochondria fusion, metabolic dysfunction and fat accumulation in male offspring, which is exacerbated by HFD or CAF exposure after weaning, potentially due to mitochondria calcium overflux.