Modulation of leptin resistance by food compounds

Key Players in the Complex Pathophysiology of Obesity: A Cross-Talk Between the Obesogenic Genes and Unraveling the Metabolic Pathway of Action of Capsaicin and Orange Peel

Obesity is a widespread prevailing health concern with multifactorial causes. Among the various defined molecular targets associated with obesity, peroxisome proliferator activated receptor gamma, leptin, ghrelin, and adiponectin play crucial roles in fundamental processes including energy balance, adipose tissue biology, and metabolic health, making them particularly significant in the study of obesity.Capsaicin and orange peel exhibit promising anti-obesity properties through their thermogenic, metabolic, and anti-inflammatory effects. Potential pathways for therapeutic approaches in the management of obesity are provided by these targets. The lipid-lowering and anti-obesity benefits of specific plant species have been highlighted in Asian medicine. Due to the potential anti-obesity qualities, capsaicin, which is derived from chilli peppers, and orange peel extract has been focused in this review. Capsaicin causes apoptosis in preadipocytes and adipocytes and suppresses adipogenesis. Citrus fruits are a significant source of bioactive substances, primarily flavonoids. Due to their ability to reduce adipocyte development and cellular lipid content, citrus polyphenols are helpful in the control of obesity. This extensive analysis offers insights into new treatment approaches for the prevention and management of obesity and metabolic syndrome by examining the interactions of molecular variables in obesity as well as the possible anti-obesity advantages of capsaicin and orange peel extract.

Epigenetic alterations in patients with anorexia nervosa-a systematic review

Anorexia nervosa (AN) is a complex metabolic and psychological disorder that is influenced by both heritable genetic components and environmental factors. Exposure to various environmental influences can lead to epigenetically induced changes in gene expression. Epigenetic research in AN is still in its infancy, and studies to date are limited in determining clear, valid links to disease onset and progression are limited. Therefore, the aim of this systematic review was to compile and critically evaluate the available results of epigenetic studies specifically in AN and to provide recommendations for future studies. In accordance with the PRISMA guidelines, a systematic literature search was performed in three different databases (PubMed, Embase, and Web of Science) through May 2023. Twenty-three original papers or conference abstracts on epigenetic studies in AN were collected. Epigenome-wide association studies (EWASs), which analyze DNA methylation across the genome in patients with AN and identify potential disease-relevant changes in promoter/regulatory regions of genes, are the most promising for future research. To date, five EWASs on AN have been published, suggesting a potential reversibility of malnutrition-induced epigenetic changes once patients recover. Hence, determining differential DNA methylation levels could serve as a biomarker for disease status or early diagnosis and might be involved in disease progression or chronification. For future research, EWASs with a larger sample size, longitudinal study design and uniform methods should be performed to contribute to the understanding of the pathophysiology of AN, the development of individual interventions and a better prognosis for affected patients.

Genetic background of juniper (Juniperus spp.) consumption predicted by fecal near-infrared spectroscopy in divergently selected goats raised in harsh rangeland environments

BACKGROUND

Junipers (Juniperus spp.) are woody native, invasive plants that have caused encroachment problems in the U.S. western rangelands, decreasing forage productivity and biodiversity. A potential solution to this issue is using goats in targeted grazing programs. However, junipers, which grow in dry and harsh environmental conditions, use chemical defense mechanisms to deter herbivores. Therefore, genetically selecting goats for increased juniper consumption is of great interest for regenerative rangeland management. In this context, the primary objectives of this study were to: 1) estimate variance components and genetic parameters for predicted juniper consumption in divergently selected Angora (ANG) and composite Boer x Spanish (BS) goat populations grazing on Western U.S. rangelands; and 2) to identify genomic regions, candidate genes, and biological pathways associated with juniper consumption in these goat populations.

RESULTS

The average juniper consumption was 22.4% (± 18.7%) and 7.01% (± 12.1%) in the BS and ANG populations, respectively. The heritability estimates (realized heritability within parenthesis) for juniper consumption were 0.43 ± 0.02 (0.34 ± 0.06) and 0.19 ± 0.03 (0.13 ± 0.03) in BS and ANG, respectively, indicating that juniper consumption can be increased through genetic selection. The repeatability values of predicted juniper consumption were 0.45 for BS and 0.28 for ANG. A total of 571 significant SNP located within or close to 231 genes in BS, and 116 SNP related to 183 genes in ANG were identified based on the genome-wide association analyses. These genes are primarily associated with biological pathways and gene ontology terms related to olfactory receptors, intestinal absorption, and immunity response.

CONCLUSIONS

These findings suggest that juniper consumption is a heritable trait of polygenic inheritance influenced by multiple genes of small effects. The genetic parameters calculated indicate that juniper consumption can be genetically improved in both goat populations.

Salvia officinalis Improves Glycemia and Suppresses Pro-inflammatory Features in Obese Rats with Metabolic Syndrome

OBJECTIVES

Obesity is regarded as the main cause of metabolic diseases and a core factor for all-cause mortality in the general population, notably from cardiovascular disease. The majority of people with type 2 diabetes have obesity and insulin resistance. Some evidence indicates that an individual with obesity is approximately 10 times more likely to develop type 2 diabetes than someone with moderate body weight. One of the most significant therapeutic herbs, Salvia officinalis (Lamiaceae) (SAGE), possesses potent medicinal importance. The aim of this article was to evaluate the anti-diabetic and antiobesity activity of SAGEAE against HFD-induced obesity in rats.

METHODS

Thirty adult albino rats were randomly divided into five equal groups: control, High-fat Diet (HFD) administrated rats, HFD + Salvia officinalis Aqueous Extract (SAGEAE) (150 mg/kg.bw.), HFD + SAGEAE (300 mg/kg.bw.) and HFD + metformin (500 mg/kg.bw.). Body weight, plasma biochemical parameters, oxidative stress, inflammatory indicators, hepatic Phosphoenolpyruvate Carboxykinase 1 (PCK1), Glucokinase (GK), brain Leptin Receptor (LepRb), Glucose Transporter-4 (GLUT4), Sirtuin 1 (SIRT1) and mRNA33-5P gene signalling mRNA levels were all assessed after 8 weeks. A histological examination of the liver was also performed to check for lipid accumulation.

RESULTS

The administration of HFD resulted in increased body weight, glucose, insulin, leptin, Total Cholesterol (TC), Triglycerides (TG), Thiobarbaturic Acid Reactive Substances (TBARS), Monocyte Chemoattractant Protein-1 (MCP1), Interleukine-6 (IL-6) and tumor necrosis factor-α (TNF- α) as well as hepatic PCK1, brain LepRb and adipose tissue mRNA33-5P gene expression. However, our findings revealed a significant reduction in adiponectin, High-density Lipoproteincholesterol (HDL-C), reduced glutathione (GSH) and Superoxide Dismutase (SOD) levels as well as the expression of hepatic GK and adipose tissue SIRT1 and GLUT4 genes. Also, administration of SAGEAE significantly normalized body weight, glucose, insulin, leptin, adiponectin, TC, TG, HDL-C, TBARs, SOD, IL-6, MCP-1 and TNF-α in plasma and liver tissue of HFD-treated rats. On the other hand, PCK1, GK, LepRb, SIRT1, GLUT4 and mRNA33-5P gene expression was enhanced in obese rats when administrated with SAGEAE. Histological and US studies support the biochemical, PCR and electrophoretic results.

CONCLUSION

The findings imply that SAGEAE could be used as a new pharmaceutical formula in the treatment of obesity.

Molecular hydrogen modulates brain glutamate/GABA-glutamine cycle in overweight humans

INTRODUCTION

We evaluated whether 12-week intake of molecular hydrogen (H2) in 5 overweight adults (3 women; age: 50.2 ±11.9 years, body mass index: 29.4 ±2.1 kg/m2) affects brain levels of the glutamate-glutamine-GABA cycle, critical amino acid neurotransmitters in the mechanism of neuronal activation during appetite regulation.

METHODS

A 1.5-T single-voxel proton magnetic resonance spectroscopy was used to assess the tissue concentrations of relevant metabolites.

RESULTS

The mean glutamate and glutamate-plus-glutamine levels at the posterior cingulate gyrus decreased significantly during the study; this was accompanied by a significant drop in GABA levels at left prefrontal white matter, and glutathione levels at anterior cingulate gyrus. No changes in the brain metabolites were found in the comparable group of overweight individuals (n = 4, 2 women; age: 41.0 ±13.9, BMI 26.8 ±1.3 kg/m2) followed-up in the past without this treatment.

CONCLUSIONS

We showed a possible hydrogen-driven upregulation of neurotransmitters involved in appetite stimulation leading to hunger suppression and weight loss. Further studies analyzing appetite-controlling metabolic pathways affected by H2 would require monitoring of additional biomarkers of satiation and satiety during different feeding regimens.

Treatment with bergamot (Citrus bergamia) leaves extract attenuates leptin resistance in obese rats

Low-grade chronic inflammation in obesity is associated with leptin resistance. In order to alleviate this pathological condition, bioactive compounds capable of attenuating oxidative stress and inflammation have been researched, and bergamot (Citrus bergamia) presents these properties. The aim was to evaluate the effect of bergamot leaves extract on leptin resistance in obese rats. Animals were divided into 2 groups: control diet (C, n = 10) and high sugar-fat diet (HSF, n = 20) for 20 weeks. After detecting hyperleptinemia, animals were divided to begin the treatment with bergamot leaves extract (BLE) for 10 weeks: C + placebo (n = 7), HSF + placebo (n = 7), and HSF + BLE (n = 7) by gavage (50 mg/kg). Evaluations included nutritional, hormonal and metabolic parameters; adipose tissue dysfunction; inflammatory, oxidative markers and hypothalamic leptin pathway. HSF group presented obesity, metabolic syndrome, adipose tissue dysfunction, hyperleptinemia and leptin resistance compared to control group. However, the treated group showed a decrease in caloric consumption and attenuation of insulin resistance. Moreover, dyslipidemia, adipose tissue function, and leptin levels showed an improvement. At the level of the hypothalamus, the treated group showed a reduction of oxidative stress, inflammation and modulation of leptin signaling. In conclusion, BLE properties were able to improve leptin resistance through recovery of the hypothalamic pathway.

Sumac (Rhus coriaria L.) powder supplementation has beneficial effects on appetite in overweight/obese women with depression: A randomized controlled trial

BACKGROUND AND PURPOSE

Appetite disturbance is a common problem in obesity and depression. The beneficial effects of polyphenols in promoting satiety have been shown. This study aimed to investigate the effects of sumac supplementation along with calorie restricted diet (CRD) on appetite in overweight and obese women with depression.

MATERIALS AND METHODS

In this trial, 60 overweight and obese women with depression were randomly assigned to receive a CRD plus 3 g/day of either sumac or placebo for 12 weeks. The appetite score, serum levels of leptin, neuropeptide Y (NPY), insulin, fasting blood sugar (FBS), homeostasis model assessment of insulin resistance (HOMA-IR), and quantitative insulin sensitivity check index (QUICKI) were assessed at baseline and at the end of the study.

RESULTS

Sumac supplementation significantly reduced the appetite score (p = 0.02), serum levels of leptin (p = 0.03), NPY (p = 0.01), insulin (p = 0.03), FBS (p = 0.03), and HOMA-IR (p = 0.02) compared to the placebo group. QUICKI increased significantly in the sumac group compared to the placebo group (p = 0.009).

CONCLUSION

Sumac along with a CRD may have some beneficial effects on appetite through possible modulatory effects on leptin resistance, insulin sensitivity, and NPY levels in overweight and obese women with depression.

Effects of a Calorie-Restricted Cafeteria Diet and Oleuropein Supplementation on Adiposity and mRNA Expression of Energy Balance Related Genes in Obese Male Rats

Supplementation with natural bioactive compounds has been proposed to be a complementary tool to the calorie-restricted diets and physical exercise programs used to tackle human overweight, obesity and Metabolic syndrome. Herein, we evaluated the effects of 14 weeks of calorie-restricted cafeteria diet either alone or combined with oral administration of the polyphenol oleuropein in obese adult male rats, compared with a control group fed standard chow and a group fed cafeteria diet. Animals were sacrificed at the age of 26 weeks and several tissues of interest were removed. The results showed that both dietary interventions reduced the adiposity index (p < 0.05 and p < 0.01, respectively), and specifically the abdominal fat depots (mesenteric: p < 0.01 and p < 0.01, respectively; and epididymal: both diets p < 0.001) and restored the decreased soleus skeletal muscle mass. Both interventions decreased leptin mRNA expression in mesenteric white adipose tissue (p < 0.05) and normalized hypothalamic Agrp mRNA expression compared to cafeteria-fed obese rats (p < 0.05). However, only the calorie-restricted cafeteria diet supplemented with oleuropein induced additional lower retroperitoneal adipose accretion (p < 0.05) and increased hypothalamic leptin receptor mRNA levels (p < 0.05). Experiments with female animals, at different doses and longer intervention periods, are needed to better determine the potential benefits of this dietary treatment.

The Protective Role of Grape Seed in Obesity and Lipid Profile: An Updated Narrative Overview of Preclinical and Clinical Studies

Obesity and dyslipidemia are common disorders universally. According to the acquired outcomes of recent studies, dietary supplementations which have great content of phenolic compounds exert protective effects against obesity and dyslipidemia. Grape [Vitis vinifera] seeds are considered attractive sources of phenolic compounds with anti-oxidative stress and anti-inflammatory effects. There are also various experimental studies describing hepatoprotective, neuroprotective, anti-aging, cardioprotective, and anti-carcinogenic effects of polyphenols isolated from grape seed, highlighting the therapeutic and biological aspects of proanthocyanidins. The present review article first discusses pharmacological, botanical, toxicological, and phytochemical characteristics of Vitis vinifera seeds and afterward designates the protective properties which are attributed to the intake of grape seeds in obesity and hyperlipidemia. Overall valuable and updated findings of this study display that polyphenol of grape seeds has meaningful impacts on the regulation of lipid profile levels and management of obesity.

Obesity as a Risk Factor for Dementia and Alzheimer's Disease: The Role of Leptin

Obesity is a growing worldwide health problem, affecting many people due to excessive saturated fat consumption, lack of exercise, or a sedentary lifestyle. Leptin is an adipokine secreted by adipose tissue that increases in obesity and has central actions not only at the hypothalamic level but also in other regions and nuclei of the central nervous system (CNS) such as the cerebral cortex and hippocampus. These regions express the long form of leptin receptor LepRb, which is the unique leptin receptor capable of transmitting complete leptin signaling, and are the first regions to be affected by chronic neurocognitive deficits, such as mild cognitive impairment (MCI) and Alzheimer's Disease (AD). In this review, we discuss different leptin resistance mechanisms that could be implicated in increasing the risk of developing AD, as leptin resistance is frequently associated with obesity, which is a chronic low-grade inflammatory state, and obesity is considered a risk factor for AD. Key players of leptin resistance are SOCS3, PTP1B, and TCPTP whose signalling is related to inflammation and could be worsened in AD. However, some data are controversial, and it is necessary to further investigate the underlying mechanisms of the AD-causing pathological processes and how altered leptin signalling affects such processes.

AgRP/NPY and POMC neurons in the arcuate nucleus and their potential role in treatment of obesity

Obesity is a major health crisis affecting over a third of the global population. This multifactorial disease is regulated via interoceptive neural circuits in the brain, whose alteration results in excessive body weight. Certain central neuronal populations in the brain are recognised as crucial nodes in energy homeostasis; in particular, the hypothalamic arcuate nucleus (ARC) region contains two peptide microcircuits that control energy balance with antagonistic functions: agouti-related peptide/neuropeptide-Y (AgRP/NPY) signals hunger and stimulates food intake; and pro-opiomelanocortin (POMC) signals satiety and reduces food intake. These neuronal peptides levels react to energy status and integrate signals from peripheral ghrelin, leptin, and insulin to regulate feeding and energy expenditure. To manage obesity comprehensively, it is crucial to understand cellular and molecular mechanisms of information processing in ARC neurons, since these regulate energy homeostasis. Importantly, a specific strategy focusing on ARC circuits needs to be devised to assist in treating obese patients and maintaining weight loss with minimal or no side effects. The aim of this review is to elucidate the recent developments in the study of AgRP-, NPY- and POMC-producing neurons, specific to their role in controlling metabolism. The impact of ghrelin, leptin, and insulin signalling via action of these neurons is also surveyed, since they also impact energy balance through this route. Lastly, we present key proteins, targeted genes, compounds, drugs, and therapies that actively work via these neurons and could potentially be used as therapeutic targets for treating obesity conditions.

Recent Advances in Research on Polyphenols: Effects on Microbiota, Metabolism, and Health

Polyphenols have attracted huge interest among researchers of various disciplines because of their numerous biological activities, such as antioxidative, antiinflammatory, antiapoptotic, cancer chemopreventive, anticarcinogenic, and antimicrobial properties, and their promising applications in many fields, mainly in the medical, cosmetics, dietary supplement and food industries. In this review, the latest scientific findings in the research on polyphenols interaction with the microbiome and mitochondria, their metabolism and health beneficial effects, their involvement in cognitive diseases and obesity development, as well as some innovations in their analysis, extraction methods, development of cosmetic formulations and functional food are summarized based on the papers presented at the 13th World Congress on Polyphenol Applications. Future implications of polyphenols in disease prevention and their strategic use as prophylactic measures are specifically addressed. Polyphenols may play a key role in our tomorrow´s food and nutrition to prevent many diseases.

Trajectory of leptin and leptin receptor in vertebrates: Structure, function and their regulation

The present review provides a comparative insight into structure, function and control of leptin system in fishes, herptiles, birds and mammals. In general, leptin acts as an anorexigenic hormone since its administration results in decrease of food intake in vertebrates. Nonetheless, functional paradox arises in fishes from contradictory observations on level of leptin during fasting and re-feeding. In addition, leptin is shown to modulate metabolic functions in fishes, reptiles, birds and mammals. Leptin also regulates reproductive and immune functions though more studies are warranted in non-mammalian vertebrates. The expression of leptin and its receptor is influenced by numerous factors including sex steroids, stress and stress-induced catecholamines and glucocorticoids though their effect in non-mammalian vertebrates is hard to be generalized due to limited studies.

Leptin decreases apoptosis and promotes the activation of primordial follicles through the phosphatidylinositol-3-kinase/protein kinase B pathway in cultured ovine ovarian tissue

This study evaluated the effects of leptin on primordial follicle survival and activation after in vitro culture of ovine ovarian tissue and if leptin acts through the phosphatidylinositol-3-kinase/protein kinase B (PI3K/Akt) pathway. Ovarian fragments were fixed for histology (fresh control) or cultured for 7 days in control medium (α-MEM+) alone or supplemented with leptin (1, 5, 10, 25 or 50 ng/ml). Follicle morphology, activation and apoptosis were analyzed. Next, the fragments were cultured in the medium that showed the best results in the absence or the presence of the PI3K inhibitor (LY294002), and immunohistostaining of p-Akt protein was assessed. After culture, the percentage of normal follicles decreased (P < 0.05) in all treatments compared with the fresh control. Moreover, control medium and 1 ng/ml leptin had similar (P > 0.05) percentages of normal follicles, which were significantly higher than those in other treatments. However, culture with 1 ng/ml leptin maintained apoptosis similarly (P > 0.05) to that of the fresh control and lower (P < 0.05) than that in α-MEM+. Leptin did not influence follicle activation (P > 0.05) compared with the control medium (α-MEM+). Culture in 1 ng/ml leptin with LY294002 decreased the normal follicles and increased apoptosis, inhibited follicle activation (P < 0.05), and reduced p-Akt immunostaining, compared with the medium containing 1 ng/ml leptin without PI3K inhibitor. In conclusion, leptin at 1 ng/ml reduces apoptosis and promotes the activation of primordial follicles compared with the fresh control after in vitro culture of ovine ovarian tissue possibly through the PI3K/Akt pathway.

Eating behaviour in contrasting adiposity phenotypes: Monogenic obesity and congenital generalized lipodystrophy

Most known types of nonsyndromic monogenic obesity are caused by rare mutations in genes of the leptin-melanocortin pathway controlling appetite and adiposity. In contrast, congenital generalized lipodystrophy represents the most extreme form of leanness in humans caused by recessive mutations in four genes involved in phospholipid/triglyceride synthesis and lipid droplet/caveolae structure. In this disease, the inability to store triglyceride in adipocytes results in hypoleptinemia and ectopic hepatic and muscle fat accumulation leading to fatty liver, hypertriglyceridemia and severe insulin resistance. As a result of hypoleptinemia, patients with lipodystrophy show alterations in eating behaviour characterized by constant increased energy intake. As it occurs in obesity caused by genetic leptin deficiency, exogenous leptin rapidly reduces hunger scores in patients with congenital generalized lipodystrophy, with additional beneficial effects on glucose homeostasis and metabolic profile normalization. The melanocortin-4 receptor agonist setmelanotide has been used in the treatment of monogenic obesities. There is only one report on the effect of setmelanotide in a patient with partial lipodystrophy resulting in mild reductions in hunger scores, with no improvements in metabolic status. The assessment of contrasting phenotypes of obesity/leanness represents an adequate strategy to understand the pathophysiology and altered eating behaviour associated with adipose tissue excessive accumulation/paucity.

Herring Milt and Herring Milt Protein Hydrolysate Are Equally Effective in Improving Insulin Sensitivity and Pancreatic Beta-Cell Function in Diet-Induced Obese- and Insulin-Resistant Mice

Although genetic predisposition influences the onset and progression of insulin resistance and diabetes, dietary nutrients are critical. In general, protein is beneficial relative to carbohydrate and fat but dependent on protein source. Our recent study demonstrated that 70% replacement of dietary casein protein with the equivalent quantity of protein derived from herring milt protein hydrolysate (HMPH; herring milt with proteins being enzymatically hydrolyzed) significantly improved insulin resistance and glucose homeostasis in high-fat diet-induced obese mice. As production of protein hydrolysate increases the cost of the product, it is important to determine whether a simply dried and ground herring milt product possesses similar benefits. Therefore, the current study was conducted to investigate the effect of herring milt dry powder (HMDP) on glucose control and the associated metabolic phenotypes and further to compare its efficacy with HMPH. Male C57BL/6J mice on a high-fat diet for 7 weeks were randomized based on body weight and blood glucose into three groups. One group continued on the high-fat diet and was used as the insulin-resistant/diabetic control and the other two groups were given the high-fat diet modified to have 70% of casein protein being replaced with the same amount of protein from HMDP or HMPH. A group of mice on a low-fat diet all the time was used as the normal control. The results demonstrated that mice on the high-fat diet increased weight gain and showed higher blood concentrations of glucose, insulin, and leptin, as well as impaired glucose tolerance and pancreatic β-cell function relative to those on the normal control diet. In comparison with the high-fat diet, the replacement of 70% dietary casein protein with the same amount of HMDP or HMPH protein decreased weight gain and significantly improved the aforementioned biomarkers, insulin sensitivity or resistance, and β-cell function. The HMDP and HMPH showed similar effects on every parameter except blood lipids where HMDP decreased total cholesterol and non-HDL-cholesterol levels while the effect of HMPH was not significant. The results demonstrate that substituting 70% of dietary casein protein with the equivalent amount of HMDP or HMPH protein protects against obesity and diabetes, and HMDP is also beneficial to cholesterol homeostasis.

Nutritional modulation of leptin expression and leptin action in obesity and obesity-associated complications

In obesity, an elevated accumulation and dysregulation of adipose tissue, due to an imbalance between energy intake and energy expenditure, usually coexists with the loss of responsiveness to leptin in central nervous system, and subsequently with hyperleptinemia. Leptin, a peptide hormone mainly produced by white adipose tissue, regulates energy homeostasis by stimulating energy expenditure and inhibiting food intake. Human obesity is characterized by increased plasma leptin levels, which have been related with different obesity-associated complications, such as chronic inflammatory state (risk factor for diabetes, cardiovascular and autoimmune diseases), as well as infertility and different types of cancer. Besides, leptin is also produced by placenta, and high leptin levels during pregnancy may be related with some pathological conditions such as gestational diabetes. This review focuses on the current insights and emerging concepts on potentially valuable nutrients and food components that may modulate leptin metabolism. Notably, several dietary food components, such as phenols, peptides, and vitamins, are able to decrease inflammation and improve leptin sensitivity by up- or down-regulation of leptin signaling molecules. On the other hand, some food components, such as saturated fatty acids may worsen chronic inflammation increasing the risk for pathological complications. Future research into nutritional mechanisms that restore leptin metabolism and signals of energy homeostasis may inspire new treatment options for obesity-related disorders.

Resistance Training Associated with Dietetic Advice Reduces Inflammatory Biomarkers in the Elderly

Aging is a biological process during which chronic low-grade inflammation is present due to changes in the immune system of the elderly. The main objective of this study is to evaluate the effects of resistance training associated with dietary advice on chronic inflammation in the elderly. We conducted a prospective intervention study in which we evaluated anthropometric parameters and inflammatory biomarkers (CRP, IL-8, CCL-2, and leptin) in 40 elderly people before and after long-term progressive resistance training (19 weeks) associated with dietary advice. The participants trained twice a week on nonconsecutive days, and the training lasted one hour with an intensity of 60-85% of 1-MR. Dietary advice was explained in person and individually focusing on foods rich in compounds with anti-inflammatory and antioxidant properties. Participants were instructed at the beginning of the training program, and dietary advice was reinforced verbally weekly. There was an improvement in body composition evidenced by a reduction in waist circumference and body fat percentage and by the increase in arm circumference, calf circumference, and corrected arm muscle area. In addition, there was a reduction in the inflammatory biomarkers CCL-2 (p = 0.01) and leptin (p < 0.01). Resistance training associated with dietary guidance can contribute to a healthy aging due to observed improvements in body composition and in the inflammatory profile of the elderly.

Dietary berries, insulin resistance and type 2 diabetes: an overview of human feeding trials

Dietary berries are a rich source of several nutrients and phytochemicals and in recent years, accumulating evidence suggests they can reduce risks of several chronic diseases, including type 2 diabetes (T2D). The objective of this review is to summarize and discuss the role of dietary berries (taken as fresh, frozen, or other processed forms) on insulin resistance and biomarkers of T2D in human feeding studies. Reported feeding trials involve different berries taken in different forms, and consequently differences in nutritional or polyphenol composition must be considered in their interpretation. Commonly consumed berries, especially cranberries, blueberries, raspberries and strawberries, ameliorate postprandial hyperglycemia and hyperinsulinemia in overweight or obese adults with insulin resistance, and in adults with the metabolic syndrome (MetS). In non-acute long-term studies, these berries either alone, or in combination with other functional foods or dietary interventions, can improve glycemic and lipid profiles, blood pressure and surrogate markers of atherosclerosis. Studies specifically in people with T2D are few, and more knowledge is needed. Nevertheless, existing evidence, although sparse, suggests that berries have an emerging role in dietary strategies for the prevention of diabetes and its complications in adults. Despite the beneficial effects of berries on diabetes prevention and management, they must be consumed as part of a healthy and balanced diet.

The effects of Vitis vinifera L. phenolic compounds on a blood-brain barrier culture model: Expression of leptin receptors and protection against cytokine-induced damage

ETHNOPHARMACOLOGICAL RELEVANCE

The medicinal properties of grapes (Vitis vinifera L.) are well known since ancient times. Ethnobotanical grape preparations, like the Ayurvedic Darakchasava are used as cardiotonic and for the treatment of cardiovascular diseases. Dried grape products are also applied in Iranian traditional medicine for memory problems, which are linked to the pathology of brain microvessels, a special part of the cardiovascular system. The anti-inflammatory and protective effects of these traditional preparations on the cardiovascular system are related to their bioactive phenolic compounds.

AIM OF THE STUDY

The blood-brain barrier (BBB), formed by brain capillaries, is not only involved in inflammatory and other diseases of the central nervous system, but also in many systemic diseases with an inflammatory component. Dietary obesity is a systemic chronic inflammatory condition in which the peripheral and central vascular system is affected. Among the cerebrovascular changes in obesity defective leptin transport across the BBB related to central leptin resistance is observed. Our aim was to study the protective effects of grape phenolic compounds epicatechin (EC), gallic acid (GA) and resveratrol (RSV) and grape-seed proanthocyanidin-rich extract (GSPE) on a cytokine-induced vascular endothelial inflammation model. Using a culture model of the BBB we investigated cytokine-induced endothelial damage and changes in the expression of leptin receptors and leptin transfer.

MATERIALS AND METHODS

For the BBB model, primary cultures of rat brain endothelial cells, glial cells and pericytes were used in co-culture. Cells were treated by tumor necrosis factor-α (TNF-α) and interleukin-1 β (IL-1β) (10 ng/ml each) to induce damage. Cell toxicity was evaluated by the measurement of impedance. The expression of leptin receptors was assessed by RT-qPCR and western blot. The production of reactive oxygen species (ROS) and nitric oxide (NO) were detected by fluorescent probes.

RESULTS

GSPE (10 μg/ml), EC (10 μM), GA (1 μM) or RSV (10 μM) did not change the viability of brain endothelial cells. The gene expression of the short leptin receptor isoform, Ob-Ra, was up-regulated by GSPE, EC and RSV, while the mRNA levels of Lrp2 and clusterin, clu/ApoJ were not affected. The tested compounds did not change the expression of the long leptin receptor isoform, Ob-Rb. RSV protected against the cytokine-induced increase in albumin permeability of the BBB model. GSPE and EC exerted an antioxidant effect and GSPE increased NO both alone and in the presence of cytokines. The cytokine-induced nuclear translocation of transcription factor NF-κB was blocked by GSPE, GA and RSV. Cytokines increased the mRNA expression of Lrp2 which was inhibited by EC. RSV increased Ob-Ra and Clu in the presence of cytokines. Cytokines elevated leptin transfer across the BBB model, which was not modified by GSPE or RSV.

CONCLUSION

Our results obtained on cell culture models confirm that natural grape compounds protect vascular endothelial cells against inflammatory damage in accordance with the ethnopharmacological use of grape preparations in cardiovascular diseases. Furthermore, grape compounds and GSPE, by exerting a beneficial effect on the BBB, may also be considered in the treatment of obesity after validation in clinical trials.

Melatonin Alleviates Glucose and Lipid Metabolism Disorders in Guinea Pigs Caused by Different Artificial Light Rhythms

Modern lifestyle-associated factors, such as high-calorie intake, high-fat diet (HFD), and excessive artificial light, are risk factors for glucose and lipid metabolism disturbances. Melatonin may be beneficial for managing obesity and diabetes; however, the underlying molecular mechanisms are not well elucidated. We aimed to assess whether melatonin has beneficial effects on constant artificial light-induced fat deposition, lipid metabolism, and insulin resistance. Guinea pigs were randomly divided into five experimental groups: control (C), HFD (H), 12 h light (12HL), 24 h light (24HL), and melatonin (M). The majority of indexes, including insulin resistance and obesity, were measured after 10 weeks. AMP-activated protein kinase α (AMPKα)/peroxisome proliferator-activated receptor-α (PPARα) pathway expression was analyzed by quantitative reverse transcription PCR and western blotting. Although insulin resistance and obesity indexes were higher in the 24HL group than in the 12HL group, they were significantly lower in the M group than in the 24HL group. Melatonin treatment markedly upregulated AMPKα, phosphorylated AMPKα (p-AMPKα), PPARα, and carnitine palmitoyl-CoA transferase 1 A (CPT1A) gene and protein expression. Melatonin may alleviate insulin resistance and obesity caused by persistent artificial light exposure in guinea pigs, likely via activation of the AMPKα/PPARα signaling pathway.

Resveratrol Treatment Enhances the Cellular Response to Leptin by Increasing OBRb Content in Palmitate-Induced Steatotic HepG2 Cells

The interaction of leptin with its hepatic longest receptor (OBRb) promotes the phosphorylation of signal transducer and activator of transcription-3 (STAT3), protecting the liver from lipid accumulation. However, leptin signalling is disrupted in hepatic steatosis, causing leptin resistance. One promising strategy to combat this problem is the use of bioactive compounds such as polyphenols. Since resveratrol (RSV) is a modulator of lipid homeostasis in the liver, we investigated whether treatment with different doses of RSV restores appropriate leptin action and fat accumulation in palmitate-induced steatotic human hepatoma (HepG2) cells. Both RSV metabolism and the expression of molecules implicated in leptin signalling were analysed. RSV at a 10 μM concentration was entirely metabolized to resveratrol-3-sulfate after 24 and counteracted leptin resistance by increasing the protein levels of OBRb. In addition, RSV downregulated the expression of lipogenic genes including fatty acid synthase (Fas) and stearoyl-CoA desaturase-1 (Scd1) without any significant change in Sirtuin-1 (SIRT1) enzymatic activity. These results demonstrate that RSV restored leptin sensitivity in a cellular model of hepatic steatosis in a SIRT1-independent manner.

Celastrol Induces Necroptosis and Ameliorates Inflammation via Targeting Biglycan in Human Gastric Carcinoma

Celastrol, a triterpene isolated from the root of traditional Chinese medicine Thunder of God Vine, possesses anti-cancer and anti-inflammatory activity to treat rheumatoid disease or as health product. Necroptosis is considered as a new approach to overcome chemotherapeutics resistance. However, whether celastrol exerts necroptosis leading to gastric cancer cell death is still unclear. Here, for the first time we showed that celastrol induced necroptosis in HGC27 and AGS gastric cancer cell lines. More importantly, celastrol down-regulated biglycan (BGN) protein, which is critical for gastric cancer migration and invasion. Furthermore, celastrol activated receptor-interacting protein 1 and 3 (RIP1 and RIP3) and subsequently promoted the translation of mixed-lineage kinase domain-like (MLKL) from cytoplasm to plasma membrane, leading to necroptosis of gastric cancer cell, which was blocked by over-expression BGN. In addition, celastrol suppressed the release of pro-inflammatory cytokines TNF-α and IL-8 in HGC27 and AGS cells, which was reversed by over-expression BGN. Taken together, we identified celastrol as a necroptosis inducer, activated RIP1/RIP3/MLKL pathway and suppressed the level of pro-inflammatory cytokines by down-regulating BGN in HGC-27 and AGS cells, which supported the feasibility of celastrol in gastric cancer therapy.

Hypothalamic Neuropeptides Expression and Hypothalamic Inflammation in Adult Rats that Were Exposed to Tobacco Smoke during Breastfeeding: Sex-Related Differences

The hypothalamus controls food intake and energy expenditure. In rats, maternal exposure to nicotine during breastfeeding alters the hypothalamic circuitry of the adult offspring, resulting in leptin resistance, neuropeptides changes and gliosis. Tobacco smoke exposure during lactation causes greater adiposity, hyperphagia and hyperleptinemia in the adult progeny. To understand the central mechanisms underlying the obese phenotype of adult rats that were directly and indirectly exposed to cigarette smoke during lactation, we investigated leptin signaling, orexigenic and anorexigenic neuropeptides expression, as well as astrocyte and microglia markers in hypothalamus. From postnatal day (PND) 3 to 21, Wistar lactating rat dams and their pups were divided into two groups: SE, smoke-exposed in a cigarette-smoking machine (four times/day); Crtl, exposed to filtered air. Offspring of both sexes were euthanized at PND180. The leptin pathway was not altered in SE animals from both sexes. SE males showed increased NPY (arcuate nucleus, ARC), CRH (paraventricular nucleus, PVN), as well as higher GFAP fiber density (ARC and PVN) and IL6 protein content. TRH (PVN) immunohistochemistry was reduced. SE females had lower CART-positive cells (ARC) and lower α-MSH immunostaining intensity (PVN and lateral hypothalamus), with no change of GFAP or IL-6. The protein contents of CX3CR1 (marker of activated microglia) and α7nAChR (anti-inflammatory marker) were not altered in both SE males and females. Neonatal cigarette smoke is deleterious to the hypothalamic circuitry, inducing changes in energy homeostasis favoring hyperphagia and decreased energy expenditure at adulthood in both sexes; however sex-dependent mechanisms were observed.

Molecular Insight into the Interaction between Epigenetics and Leptin in Metabolic Disorders

Nowadays, it is well-known that the deregulation of epigenetic machinery is a common biological event leading to the development and progression of metabolic disorders. Moreover, the expression level and actions of leptin, a vast adipocytokine regulating energy metabolism, appear to be strongly associated with epigenetics. Therefore, the aim of this review was to summarize the current knowledge of the epigenetic regulation of leptin as well as the leptin-induced epigenetic modifications in metabolic disorders and associated phenomena. The collected data indicated that the deregulation of leptin expression and secretion that occurs during the course of metabolic diseases is underlain by a variation in the level of promoter methylation, the occurrence of histone modifications, along with miRNA interference. Furthermore, leptin was proven to epigenetically regulate several miRNAs and affect the activity of the histone deacetylases. These epigenetic modifications were observed in obesity, gestational diabetes, metabolic syndrome and concerned various molecular processes like glucose metabolism, insulin sensitivity, liver fibrosis, obesity-related carcinogenesis, adipogenesis or fetal/early postnatal programming. Moreover, the circulating miRNA profiles were associated with the plasma leptin level in metabolic syndrome, and miRNAs were found to be involved in hypothalamic leptin sensitivity. In summary, the evidence suggests that leptin is both a target and a mediator of epigenetic changes that develop in numerous tissues during metabolic disorders.

Anti-Obesity Effect of Carotenoids: Direct Impact on Adipose Tissue and Adipose Tissue-Driven Indirect Effects

This review summarizes current knowledge on the biological relevance of carotenoids and some of their metabolites in obesity management. The relationship between carotenoids and obesity is considered in clinical studies and in preclinical studies. Adipose tissue is a key organ in obesity etiology and the main storage site for carotenoids. We thus first describe carotenoid metabolism in adipocyte and adipose tissue and the effects of carotenoids on biological processes in adipose tissue that may be linked to obesity management in in vitro and preclinical studies. It is also now well established that the brain is strongly involved in obesity processes. A section is accordingly devoted to the potential effect of carotenoids on obesity via their direct and/or adipose tissue-driven indirect biological effects on the brain.

A 6-week supplementation with grape pomace to subjects at cardiometabolic risk ameliorates insulin sensitivity, without affecting other metabolic syndrome markers

Grape polyphenols have shown a promising role in the modulation of metabolic syndrome (MetS), mostly in animal models. However, clinical studies are scarce and they usually only consider a fraction of polyphenols, ignoring the non-extractable polyphenols (high molecular weight compounds or associated with macromolecules such as dietary fibre). This study aimed at evaluating the effect of grape pomace, rich in both extractable and non-extractable polyphenols, on markers of MetS. Fifty subjects (22 women) aged 20-65 with at least two MetS factors were randomly assigned to the product (daily dose of 8 g of dried grape pomace) or to the control group in a 6 week crossover design with a 4 week wash-out. Samples were collected at the beginning and at the end of both periods; half of the participants were subjected to an oral glucose tolerance test at the beginning and the end of the supplementation period. Grape pomace supplementation significantly improved fasting insulinaemia (p < 0.01), without affecting other cardiometabolic risk parameters. A tendency towards an improvement in postprandial insulinaemia was observed, particularly in those subjects with higher fasting insulin levels. Therefore, supplementation with grape pomace may be a strategy for improving insulin sensitivity in subjects at high cardiometabolic risk.

Mango phenolics increase the serum apolipoprotein A1/B ratio in rats fed high cholesterol and sodium cholate diets

BACKGROUND

Serum lipoproteins are in dynamic equilibrium, partially controlled by the apolipoprotein A1 to apolipoprotein B ratio (APOA1/APOB). Freeze-dried mango pulp (FDM) is a rich source of phenolic compounds (MP) and dietary fiber (MF), although their effects on lipoprotein metabolism have not yet been studied.

RESULTS

Thirty male Wistar rats were fed with four different isocaloric diets (3.4 kcal g^-1 ) for 12 weeks: control diet, high cholesterol (8 g kg^-1 ) + sodium cholate (2 g kg^-1 ) diet either alone or supplemented with MF (60 g kg^-1 ), MP (1 g kg^-1 ) or FDM (50 g kg^-1 ). MP and FDM reduced food intake, whereas MF and MP tended to increase serum APOA1/APOB ratio, independently of their hepatic gene expression. This suggests that lipoprotein metabolism was favorably altered by mango bioactives, MP also mitigated the non-alcoholic steatohepatitis that resulted from the intake of this diet.

CONCLUSION

We propose that phenolics are the most bioactive components of mango pulp, acting as anti-atherogenic and hepatoprotective agents, with a mechanism of action tentatively based on changes to the main protein components of lipoproteins. © 2018 Society of Chemical Industry.

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

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

Phenethyl isothiocyanate activates leptin signaling and decreases food intake

Obesity, a principal risk factor for the development of diabetes mellitus, heart disease, and hypertension, is a growing and serious health problem all over the world. Leptin is a weight-reducing hormone produced by adipose tissue, which decreases food intake via hypothalamic leptin receptors (Ob-Rb) and the Janus kinase 2/signal transducer and activator of transcription 3 (JAK2/STAT3) signaling pathway. Protein tyrosine phosphatase 1B (PTP1B) negatively regulates leptin signaling by dephosphorylating JAK2, and the increased activity of PTP1B is implicated in the pathogenesis of obesity. Hence, inhibition of PTP1B may help prevent and reduce obesity. In this study, we revealed that phenethyl isothiocyanate (PEITC), a naturally occurring isothiocyanate in certain cruciferous vegetables, potently inhibits recombinant PTP1B by binding to the reactive cysteinyl thiol. Moreover, we found that PEITC causes the ligand-independent phosphorylation of Ob-Rb, JAK2, and STAT3 by inhibiting cellular PTP1B in differentiated human SH-SY5Y neuronal cells. PEITC treatment also induced nuclear accumulation of phosphorylated STAT3, resulting in enhanced anorexigenic POMC expression and suppressed orexigenic NPY/AGRP expression. We demonstrated that oral administration of PEITC to mice significantly reduces food intake, and stimulates hypothalamic leptin signaling. Our results suggest that PEITC might help prevent and improve obesity.

Thymol feed supplementation in quail alters the percentages of nutritionally relevant egg yolk fatty acids: effects throughout incubation

BACKGROUND

Polyunsaturated fatty acids (PUFA) are crucial components of egg yolk and particularly prone to oxidative damage, generating losses of nutrients for embryonic development and influencing the quality of eggs for human consumption. The aim of this study was to evaluate whether dietary thymol (a natural antioxidant) is related to changes in quail egg yolk total (T), triglyceride (TG) and phospholipid (PL) fatty acid composition at different stages of embryo development. Thus female Japanese quail (100 days of age) were assigned to one of two dietary treatments (12 individuals each): CON (basal diet) or THY (0.0016 mol thymol day^-1 per bird). After 2 weeks of supplementation, eggs were incubated and samples were obtained at 0, 4 and 16 days of embryonic development.

RESULTS

In 0 day THY eggs, α-linolenic acid and n-3 PUFA in T and TG, docosahexaenoic acid and PUFA in T and arachidonic acid in TG were increased, while saturated fatty acids (SFA) in T were reduced. From 4 days on, PUFA, n-3 PUFA and SFA from T and TG in THY eggs were found to be similar to those of CON eggs. The changes in PL throughout incubation were similar in both dietary treatments.

CONCLUSION

Thymol would provide the embryo with PUFA for synthesis/deposition in membranes and/or assign to supply energy. Additionally, thymol supplementation would be advisable for the production of healthier table eggs. © 2017 Society of Chemical Industry.

The hyperleptinemia state can downregulate cardiorespiratory fitness and energy expenditure in obese women

INTRODUCTION

In general, in obese people a state of hyperleptinemia may impair both energy balance and the inflammatory process. However, it has not been fully investigated whether there is a relationship between hyperleptinemia and cardiorespiratory fitness (CRF) and resting energy expenditure (REE), in obese women.

METHODS

83 obese women were enrolled in this cross-sectional study. Anthropometric measures, body composition, REE, CRF and serum concentration of leptin were measured. Pearson's correlation coefficient was performed to examine the relationship between circulating leptin level and other clinical variables. Multiple regression analysis was applied to determine predictors of REE and CRF. Effects were considered significant at p≤0.05.

RESULTS

The most important finding in the present study is that the hyperleptinemia state was inversely correlated with CRF (r=-0.382, p=0.001) and REE (r=-0.447, p<0.001). Moreover, a positive correlation with fat mass was confirmed (r=0.419, p<0.001). In addition, hyperleptinemia was an independent negative predictor of REE (r²=-2.649, p=0.010) and CRF (r²=-2.335, p=0.023).

CONCLUSION

Together our results may suggest a vicious cycle between the state of hyperleptinemia and a decrease in energy expenditure and cardiorespiratory fitness in obese women, which can impair whole body energy homeostasis. This information is important to contribute to clinical practices.

Weight Loss and Appetite Control in Women

PURPOSE OF REVIEW

The aim of this review is to describe and discuss weight loss-induced variations in appetite in women and factors responsible for these changes.

RECENT FINDINGS

Studies have shown postweight loss increases in fasting and postprandial appetite in individuals engaged in weight loss trials, especially in women. Similarly, appetite-related peptides associated to the homeostatic control of feeding, such as leptin, ghrelin and peptide YY, were also found to be altered in way that promotes increased appetite after weight loss interventions. Sustained caloric deficits also drive increases in the frequency and strength of food cravings, food reward and seem to enhance oro-sensory sensations in women who lost weight. The menstrual cycle has also been to shown to influence caloric intake in women, more specifically food cravings. On the other hand, caloric restriction seems to increase cognitive restraint, decrease habitual disinhibition and susceptibility to hunger among women engaged in weight loss trials. Neural analysis corroborates these results, showing increased activation in brain areas involved in food reward and self-control processing. In conclusion, evidence supports that weight loss increases appetite sensations, and promotes changes in homeostatic and non-homeostatic control of feeding, which collectively seem to upregulate appetite in women.

Cilia and Obesity

The ciliopathies Bardet-Biedl syndrome and Alström syndrome cause obesity. How ciliary dysfunction leads to obesity has remained mysterious, partly because of a lack of understanding of the physiological roles of primary cilia in the organs and pathways involved in the regulation of metabolism and energy homeostasis. Historically, the study of rare monogenetic disorders that present with obesity has informed our molecular understanding of the mechanisms involved in nonsyndromic forms of obesity. Here, we present a framework, based on genetic studies in mice and humans, of the molecular and cellular pathways underlying long-term regulation of energy homeostasis. We focus on recent progress linking these pathways to the function of the primary cilia with a particular emphasis on the roles of neuronal primary cilia in the regulation of satiety.

Celastrol: A Spectrum of Treatment Opportunities in Chronic Diseases

The identification of new bioactive compounds derived from medicinal plants with significant therapeutic properties has attracted considerable interest in recent years. Such is the case of the Tripterygium wilfordii (TW), an herb used in Chinese medicine. Clinical trials performed so far using its root extracts have shown impressive therapeutic properties but also revealed substantial gastrointestinal side effects. The most promising bioactive compound obtained from TW is celastrol. During the last decade, an increasing number of studies were published highlighting the medicinal usefulness of celastrol in diverse clinical areas. Here we systematically review the mechanism of action and the therapeutic properties of celastrol in inflammatory diseases, namely, rheumatoid arthritis, systemic lupus erythematosus, inflammatory bowel diseases, osteoarthritis and allergy, as well as in cancer, neurodegenerative disorders and other diseases, such as diabetes, obesity, atherosclerosis, and hearing loss. We will also focus in the toxicological profile and limitations of celastrol formulation, namely, solubility, bioavailability, and dosage issues that still limit its further clinical application and usefulness.

Translating the biology of adipokines in atherosclerosis and cardiovascular diseases: Gaps and open questions

AIM

Critically discuss the available data, to identify the current gaps and to provide key concepts that will help clinicians in translating the biology of adipokines in the context of atherosclerosis and cardio-metabolic diseases.

DATA SYNTHESIS

Adipose tissue is nowadays recognized as an active endocrine organ, a function related to the ability to secrete adipokines (such as leptin and adiponectin) and pro-inflammatory cytokines (tumor necrosis factor alpha and resistin). Studies in vitro and in animal models have observed that obesity status presents a chronic low-grade inflammation as the consequence of the immune cells infiltrating the adipose tissue as well as adipocytes. This inflammatory signature is often related to the presence of cardiovascular diseases, including atherosclerosis and thrombosis. These links are less clear in humans, where the role of adipokines as prognostic marker and/or player in cardiovascular diseases is not as clear as that observed in experimental models. Moreover, plasma adipokine levels might reflect a condition of adipokine-resistance in which adipokine redundancy occurs. The investigation of the cardio-metabolic phenotype of carriers of single nucleotide polymorphisms affecting the levels or function of a specific adipokine might help determine their relevance in humans. Thus, the aim of the present review is to critically discuss the available data, identify the current gaps and provide key concepts that will help clinicians translate the biology of adipokines in the context of atherosclerosis and cardio-metabolic diseases.

Proanthocyanidins potentiate hypothalamic leptin/STAT3 signalling and Pomc gene expression in rats with diet-induced obesity

Objective:

Dietary obesity is usually linked with hypothalamic leptin resistance, in which the primary impact is an interference in the homeostatic control of body weight and appetite. Notably, proanthocyanidins (PACs), which are the most abundant phenolic compounds present in human diet, modulate adiposity and food intake. The aim of this study was to assess whether PACs could re-establish appropriate leptin signalling in both the hypothalamus and peripheral tissues.

Design:

Male Wistar rats were fed either a standard chow diet (STD group, n=7) or a cafeteria diet (CD) for 13 weeks. The CD-fed rats were treated with either grape-seed PAC extract (GSPE) at 25 mg  per kg of body weight per day (CD+GSPE group, n=7) or with the vehicle (CD group, n=7) for the last 21 days of the study period. Specific markers for intracellular leptin signalling, inflammation and endoplasmic reticulum stress in the hypothalamus, liver, mesenteric white adipose tissue and skeletal muscle were analysed using immunoblotting and quantitative PCR.

Results:

GSPE treatment significantly reduced the food intake but did not reverse the hyperleptinemia and body wt gain assessed. However, the animals treated with GSPE exhibited greater hypothalamic activation of signal transducer and activator of transcription-3, which was associated with a rise in the Pomc mRNA levels compared with the CD group. In addition, this restoration of leptin responsiveness was accompanied by lower local inflammation and increased Sirt1 gene expression. The effects of the GSPE treatment in the peripheral tissues were not as evident as those in the hypothalamus, although the GSPE treatment significantly restored the mRNA levels of Socs3 and Ptp1b in the skeletal muscle.

Conclusions:

The use of GSPE reduces hyperphagia and improves the central and peripheral leptin resistance associated with diet-induced obesity. Our results suggest that GSPE could exert these effects partially by increasing Sirt1 expression and preventing hypothalamic inflammation.

Creosote Bush (Larrea tridentata) Improves Insulin Sensitivity and Reduces Plasma and Hepatic Lipids in Hamsters Fed a High Fat and Cholesterol Diet

Creosote bush, Larrea tridentata (Sesse y Moc. Ex DC, Zygophyllaceae) is a shrub found in the deserts of Northern Mexico and Southwestern United States. In traditional medicine, it is used to treat a variety of illnesses including type 2 diabetes. The present study aims to investigate the effects of creosote bush ethanolic extract on plasma and liver parameters associated with the metabolic syndrome in hamsters fed a high fat and cholesterol diet (HFD), comparing them with those induced by ezetimibe (EZ). Seven groups of six hamsters each were formed. Six groups were fed HFD for 2 weeks. The following 2 weeks, the HFD groups received: (1) only HFD, (2) HFD + 3 mg% EZ, (3) HFD + 0.2% creosote bush ethanolic extract, (4) only standard diet (Std Diet), (5) Std Diet + 3 mg% EZ, (6) Std Diet + 0.2% creosote bush ethanolic extract. The beneficial effects of creosote bush ethanolic extract in the HFD hamster model were a reduction of insulin resistance, associated with lower serum insulin and leptin, lower hepatic lipid peroxidation and higher liver antioxidant capacity. Plasma and liver lipids tended or were reduced to values closer to those of animals fed standard diet. A similar effect on lipids was induced by EZ, although with even lower hepatic cholesterol and total lipids concentrations. In general, the change from HFD to standard diet plus ethanolic extract induced the same but deeper changes, including a reduction in plasma glucose and an increase in the percentage of HDL cholesterol. Unlike creosote bush extract, EZ increased food consumption and neutral fecal steroids, with no significant effect on body weight, epididymal fat pads, liver peroxidation or antioxidant capacity. Also EZ did not modify serum insulin and leptin. However, insulin sensitivity improved to values similar to those induced by the extract. This suggests that the mechanism of action of creosote bush ethanolic extract is different to inhibition of cholesterol absorption or increase excretion. The ethanolic extract of L. tridentata could be useful in the treatment of the metabolic syndrome.