Leptin levels in human and rodent: measurement of plasma leptin and ob RNA in obese and weight-reduced subjects

Metabolic Diseases and Down Syndrome: How Are They Linked Together?

Down syndrome is a genetic disorder caused by the presence of a third copy of chromosome 21, associated with intellectual disabilities. Down syndrome is associated with anomalies of both the nervous and endocrine systems. Over the past decades, dramatic advances in Down syndrome research and treatment have helped to extend the life expectancy of these patients. Improved life expectancy is obviously a positive outcome, but it is accompanied with the need to address previously overlooked complications and comorbidities of Down syndrome, including obesity and diabetes, in order to improve the quality of life of Down syndrome patients. In this focused review, we describe the associations between Down syndrome and comorbidities, obesity and diabetes, and we discuss the understanding of proposed mechanisms for the association of Down syndrome with metabolic disorders. Drawing molecular mechanisms through which Type 1 diabetes and Type 2 diabetes could be linked to Down syndrome could allow identification of novel drug targets and provide therapeutic solutions to limit the development of metabolic and cognitive disorders.

Sucralose and Cardiometabolic Health: Current Understanding from Receptors to Clinical Investigations

The excess consumption of added sugar is consistently found to be associated with weight gain, and a higher risk of type 2 diabetes mellitus, coronary heart disease, and stroke. In an effort to reduce the risk of cardiometabolic disease, sugar is frequently replaced by low- and null-calorie sweeteners (LCSs). Alarmingly, though, emerging evidence indicates that the consumption of LCSs is associated with an increase in cardiovascular mortality risk that is amplified in those who are overweight or obese. Sucralose, a null-caloric high-intensity sweetener, is the most commonly used LCS worldwide, which is regularly consumed by healthy individuals and patients with metabolic disease. To explore a potential causal role for sucralose in increased cardiovascular risk, this present review summarizes the preclinical and clinical data from current research detailing the effects of sucralose on systems controlling food intake, glucose homeostasis, and gut microbiota.

The Role of Periprostatic Adipose Tissue on Prostate Function in Vascular-Related Disorders

The lower urinary tract symptoms (LUTS) secondary to benign prostatic hyperplasia (BPH) are highly prevalent worldwide. Clinical and experimental data suggest that the incidence of LUTS-BPH is higher in patients with vascular-related disorders such as in pelvic ischemia, obesity and diabetes as well as in the ageing population. Obesity is an important risk factor that predisposes to glucose intolerance, insulin resistance, dyslipidemia, type 2 diabetes mellitus and cardiovascular disorders. Prospective studies showed that obese men are more likely to develop LUTS-BPH than non-obese men. Yet, men with greater waist circumferences were also at a greater risk of increased prostate volume and prostate-specific antigen than men with lower waist circumference. BPH is characterized by an enlarged prostate and increased smooth muscle tone, thus causing urinary symptoms. Data from experimental studies showed a significant increase in prostate and epididymal adipose tissue weight of obese mice when compared with lean mice. Adipose tissues that are in direct contact with specific organs have gained attention due to their potential paracrine role. The prostate gland is surrounded by periprostatic adipose tissue (PPAT), which is believed to play a paracrine role by releasing growth factors, pro-inflammatory, pro-oxidant, contractile and anti-contractile substances that interfere in prostate reactivity and growth. Therefore, this review is divided into two main parts, one focusing on the role of adipokines in the context of obesity that can lead to LUTS/BPH and the second part focusing on the mediators released from PPAT and the possible pathways that may interfere in the prostate microenvironment.

Zinc Supplementation Might Not Affect Serum Leptin and Adiponectin Levels in Adults: A Systematic Review and Meta-Analysis of Randomized Controlled Clinical Trials

Background:

Zinc as one of the important trace elements in human health has been suggested to be a supplement for modifying the level of adipokines, whereas findings from studies have been inconsistent. This study aimed to systematically review the evidence provided by randomized controlled trials (RCTs) regarding the effect of zinc supplementation on serum adipokines levels.

Methods:

PubMed, Google Scholar, Web of Science, and Scopus were systematically searched up to June 2019. The mean differences and their corresponding standard deviations (SDs) of changes in serum adipokines levels were used as effect size.

Results:

Eight eligible RCTs (leptin n=6, adiponectin n=3) were included in the current study. There were no significant changes in serum leptin levels [weighted mean difference (WMD) =0.60 ng/ml, 95% confidence interval (CI): −1.78, 2.99; I-squared (I²) = 64.3%] and adiponectin levels (WMD = 1.09 ng/ml, 95% CI: −0.76, 3.18, I² = 78.8%) following zinc supplementation compared to placebo group. These findings did not change after considering several subgroups including gender, study duration, health status, body weight and the type of zinc used for supplementation.

Conclusion:

No evidence was found to support the efficacy of dietary zinc supplements on serum levels of adipokines. Further, high-quality, long-term controlled clinical trials are warranted to confirm these findings.

Obesity, Type 2 Diabetes, and Cancer Risk

Obesity and type 2 diabetes have both been associated with increased cancer risk and are becoming increasingly prevalent. Metabolic abnormalities such as insulin resistance and dyslipidemia are associated with both obesity and type 2 diabetes and have been implicated in the obesity-cancer relationship. Multiple mechanisms have been proposed to link obesity and diabetes with cancer progression, including an increase in insulin/IGF-1 signaling, lipid and glucose uptake and metabolism, alterations in the profile of cytokines, chemokines, and adipokines, as well as changes in the adipose tissue directly adjacent to the cancer sites. This review aims to summarize and provide an update on the epidemiological and mechanistic evidence linking obesity and type 2 diabetes with cancer, focusing on the roles of insulin, lipids, and adipose tissue.

Promoter Methylation of LEP and LEPR before and after Bariatric Surgery: A Cross-Sectional Study

INTRODUCTION

DNA methylation constitutes one important epigenetic mechanism that regulates gene expression in human cells. With regard to obesity, bariatric surgery-induced weight loss has been associated with promoter methylation changes in several genes. Hyperleptinemia is a characteristic feature of obesity. The underlying regulating mechanisms have not yet been completely elucidated.

METHODS

We investigated the methylation of the promoters of the leptin gene (LEP) and the leptin receptor gene (LEPR) as well as leptin expression in pre- and postbariatric surgery patients using a comparative cross-sectional design.

RESULTS

Our results revealed significantly higher LEP promoter methylation patterns in prebariatric surgery patients compared to postoperatively. DNA methylation of the LEPR promoter was significantly higher in the postoperative group. Moreover, we found significantly higher leptin serum levels in patients before the bariatric surgery than afterwards.

DISCUSSION

These findings strengthen the suggestion that there is an association between LEP expression and LEP methylation in obesity. We suggest that the epigenetic profile of LEP might be influenced by leptin serum levels in the form of a regulating feedback mechanism.

Recent advances and future avenues in understanding the role of adipose tissue cross talk in mediating skeletal muscle mass and function with ageing

Sarcopenia, broadly defined as the age-related decline in skeletal muscle mass, quality, and function, is associated with chronic low-grade inflammation and an increased likelihood of adverse health outcomes. The regulation of skeletal muscle mass with ageing is complex and necessitates a delicate balance between muscle protein synthesis and degradation. The secretion and transfer of cytokines, long non-coding RNAs (lncRNAs) and microRNAs (miRNAs), both discretely and within extracellular vesicles, have emerged as important communication channels between tissues. Some of these factors have been implicated in regulating skeletal muscle mass, function, and pathologies and may be perturbed by excessive adiposity. Indeed, adipose tissue participates in a broad spectrum of inter-organ communication and obesity promotes the accumulation of macrophages, cellular senescence, and the production and secretion of pro-inflammatory factors. Pertinently, age-related sarcopenia has been reported to be more prevalent in obesity; however, such effects are confounded by comorbidities and physical activity level. In this review, we provide evidence that adiposity may exacerbate age-related sarcopenia and outline some emerging concepts of adipose-skeletal muscle communication including the secretion and processing of novel myokines and adipokines and the role of extracellular vesicles in mediating inter-tissue cross talk via lncRNAs and miRNAs in the context of sarcopenia, ageing, and obesity. Further research using advances in proteomics, transcriptomics, and techniques to investigate extracellular vesicles, with an emphasis on translational, longitudinal human studies, is required to better understand the physiological significance of these factors, the impact of obesity upon them, and their potential as therapeutic targets in combating muscle wasting.

Hypothesis paper: electroacupuncture targeting the gut-brain axis to modulate neurocognitive determinants of eating behavior-toward a proof of concept in the obese minipig model

Acupuncture has thousands of years of history and perspective for the treatment of many health problems and disorders. Beneficial effects of acupuncture on obesity have been demonstrated at various levels in animals and clinical trials, with almost no adverse effect, even when combined with local electrical stimulation, i.e., electroacupuncture (EA), a way to potentiate the effects of acupuncture. However, there is still scattered evidence about the impact of EA on brain functions related to the control of eating behavior, and notably on the gut-brain axis mechanisms involved in these putative central modulations. During the past 10 years, we have described a convincing diet-induced obese minipig model, and successfully implemented brain imaging and neurocognitive approaches to challenge mechanistic hypotheses and innovative therapeutic strategies. In the present article, we propose to confront the current literature on the acupuncture and EA effects on the gut-brain axis and obesity with the latest developments in nutrition and neuroscience research using the minipig model. Our aims are to (a) elaborate functional hypotheses on the gut-brain mechanisms underlying EA effects on obesity, and especially on the role of the vagus nerve, and (b) present the rational for testing these hypotheses in the minipig model.

Tissue-Specific Effects of Leptin on Glucose and Lipid Metabolism

The discovery of leptin was intrinsically associated with its ability to regulate body weight. However, the effects of leptin are more far-reaching and include profound glucose-lowering and anti-lipogenic effects, independent of leptin's regulation of body weight. Regulation of glucose metabolism by leptin is mediated both centrally and via peripheral tissues and is influenced by the activation status of insulin signaling pathways. Ectopic fat accumulation is diminished by both central and peripheral leptin, an effect that is beneficial in obesity-associated disorders. The magnitude of leptin action depends upon the tissue, sex, and context being examined. Peripheral tissues that are of particular relevance include the endocrine pancreas, liver, skeletal muscle, adipose tissues, immune cells, and the cardiovascular system. As a result of its potent metabolic activity, leptin is used to control hyperglycemia in patients with lipodystrophy and is being explored as an adjunct to insulin in patients with type 1 diabetes. To fully understand the role of leptin in physiology and to maximize its therapeutic potential, the mechanisms of leptin action in these tissues needs to be further explored.

Adverse effects of metabolic disorders in childhood on adult reproductive function and fertility in the male

Over the last 50 years, there has been a steady decline in fertility rates in humans, which has occurred in parallel with an increasing incidence of obesity and metabolic disorders. The potential impact of these disorders and plausible mechanisms by which they negatively influence male reproduction are only partly understood and published data are often controversial. Obesity is one of the most important health challenges worldwide and is becoming more prevalent in children and adolescents. Obesity, the metabolic syndrome and related co-morbidities can lead to impaired male reproductive function, including adverse effects on spermatogenesis and steroidogenesis as illustrated by reduced sperm number and quality, decreased testosterone levels and elevated inflammatory markers. The incidence of diabetes mellitus type I is also dramatically increasing and may negatively impact spermatogenesis and testicular function, resulting in decreased serum testosterone and epididymal weight. In this review, we summarize and discuss the effects of metabolic diseases that typically develop during childhood and adolescence on later reproductive function and fertility. While impact on reproductive health is likely observed in both sexes, we have chosen to focus on the male in the current review. Specifically, we illustrate adverse effects of obesity, type 1 diabetes, the metabolic syndrome and insulin resistance on sperm function and testosterone metabolism. Identification of pathophysiological mechanisms during childhood may open up new avenues for early prevention and treatment resulting in better reproductive outcomes and improved fertility rates during adulthood.

Physical activity and cancer risk. Actual knowledge and possible biological mechanisms

Background

Scientific evidence has shown that an increase in regular physical activity is associated with a decrease in the development of many types of cancer. Potential mechanisms that link physical activity to reduced cancer risk include a decrease in systemic inflammation, hyperinsulinemia, insulin-like growth factor (IGF-I), sex hormones, pro-inflammatory leptin and other obesity-related cytokines, and a significant increase in anti-inflammatory adiponectin levels. In addition, physical activity improves immune function and the composition and diversity of the gastrointestinal microbiota. Moderate physical activity is important for cancer protection, but the most significant changes in the inflammatory profile are conferred by physical activity performed at higher intensities. Thus, there is a need for further investigation into the type, intensity, and duration of physical activity for the prevention of some types of cancer and the development of effective recommendations.

Conclusions

There is a strong evidence that physical activity of moderate to vigorous intensity protects against colon and breast cancer, and probably against cancer at all other sites.

The Leptin System and Diet: A Mini Review of the Current Evidence

Leptin promotes satiety and modulates energy balance and weight. Diet-induced obesity leads to leptin resistance, exacerbating overeating. We reviewed the literature on the relationship between diet and leptin, which suggests that addressing leptin resistance through dietary interventions can contribute counteracting obesity. Albeit some limitations (e.g., limited rigor, small samples sizes), studies in animals and humans show that diets high in fat, carbohydrates, fructose, and sucrose, and low in protein are drivers of leptin resistance. Despite methodological heterogeneity pertaining to this body of literature, experimental studies show that energy-restricted diets can reduce leptinemia both in the short and long term and potentially reverse leptin resistance in humans. We also discuss limitations of this evidence, future lines of research, and implications for clinical and public health translations. Main limitations include the lack of a single universally-accepted definition of leptin resistance, and of adequate ways to accurately measure it in humans. The use of leptin sensitizers (drugs) and genetically individualized diets are alternatives against leptin resistance that should be further researched in humans. The tested very-low-energy intervention diets are challenging to translate into wide clinical or population recommendations. In conclusion, the link between nutritional components and leptin resistance, as well as research indicating that this condition is reversible, emphasizes the potential of diet to recover sensitivity to this hormone. A harmonized definition of leptin resistance, reliable methods to measure it, and large-scale, translational, clinical, and precision nutrition research involving rigorous methods are needed to benefit populations through these approaches.

Adipokine signatures of subcutaneous and visceral abdominal fat in normal-weight and obese women with different metabolic profiles

INTRODUCTION

Metabolic syndrome arises from abnormal adipose function accompanied by insulin resistance. As early factors reflecting/impacting lipid storage dysfunction of adipose tissues, we sought to determine adipokine levels in subcutaneous and visceral adipose tissues (SAT and VAT).

MATERIAL AND METHODS

Gene and protein expression levels of leptin, adiponectin, and resistin were analysed in SAT and VAT of normal-weight and overweight/obese women, subclassified according to insulin resistance index, triglyceride, total, low-density lipoprotein (LDL) and high-density lipoprotein (HDL) cholesterol levels into metabolically healthy and "at risk" groups.

RESULTS

Compared with normal-weight women, obese women had higher serum leptin levels (p < 0.05), as well as increased leptin gene and protein expression in VAT. Conversely, expression levels of leptin were lower in SAT of obese women, and minor in the SAT of "at risk" groups of women, compared with weight-matched healthy groups. In addition, lower adiponectin levels were detected in SAT of metabolically healthy obese women (p < 0.01), and lower in SAT and VAT (p < 0.05) of "at risk" obese women compared to healthy, obese women. Significant differences in resistin levels were only observed in obese women; resistin gene expression was higher in VAT and SAT of obese, compared to normal-weight women. However, higher gene expression was not consistent with protein expression of resistin.

CONCLUSIONS

Low adiponectin in both examined adipose tissues and inappropriate leptin expression levels in SAT appear to be important characteristics of obesity-related metabolic syndrome. Intriguingly, this adipokine dysregulation is primary seen in SAT, suggesting that endocrine dysfunction in this abdominal depot may be an early risk sign of metabolic syndrome.

Leptin Receptor Expressing Neurons in the Substantia Nigra Regulate Locomotion, and in The Ventral Tegmental Area Motivation and Feeding

Leptin is an anorexigenic hormone, important in the regulation of body weight. Leptin plays a role in food reward, feeding, locomotion and anxiety. Leptin receptors (LepR) are expressed in many brain areas, including the midbrain. In most studies that target the midbrain, either all LepR neurons of the midbrain or those of the ventral tegmental area (VTA) were targeted, but the role of substantia nigra (SN) LepR neurons has not been investigated. These studies have reported contradicting results regarding motivational behavior for food reward, feeding and locomotion. Since not all midbrain LepR mediated behaviors can be explained by LepR neurons in the VTA alone, we hypothesized that SN LepR neurons may provide further insight. We first characterized SN LepR and VTA LepR expression, which revealed LepR expression mainly on DA neurons. To further understand the role of midbrain LepR neurons in body weight regulation, we chemogenetically activated VTA LepR or SN LepR neurons in LepR-cre mice and tested for motivational behavior, feeding and locomotion. Activation of VTA LepR neurons in food restricted mice decreased motivation for food reward (p=0.032) and food intake (p=0.020), but not locomotion. In contrast, activation of SN LepR neurons in food restricted mice decreased locomotion (p=0.025), but not motivation for food reward or food intake. Our results provide evidence that VTA LepR and SN LepR neurons serve different functions, i.e. activation of VTA LepR neurons modulated motivation for food reward and feeding, while SN LepR neurons modulated locomotor activity.

The infundibular peptidergic neurons and glia cells in overeating, obesity, and diabetes

Dysfunctional regulation of energy homeostasis results in increased bodyweight and obesity, eventually leading to type 2 diabetes mellitus. The infundibular nucleus (IFN) of the hypothalamus is the main regulator of energy homeostasis. The peptidergic neurons and glia cells of the IFN receive metabolic cues concerning energy state of the body from the circulation. The IFN can monitor hormones like insulin and leptin and nutrients like glucose and fatty acids. All these metabolic cues are integrated into an output signal regulating energy homeostasis through the release of neuropeptides. These neuropeptides are released in several inter- and extrahypothalamic brain regions involved in regulation of energy homeostasis. This review will give an overview of the peripheral signals involved in the regulation of energy homeostasis, the peptidergic neurons and glial cells of the IFN, and will highlight the main intra-hypothalamic projection sites of the IFN.

State of hormonal balance in adolescent girls with menstrual function disorders associated with obesity

Investigation of the mechanisms promoting the development of menstrual function disorders associated with obesity in adolescent girls is one of the most important issues of modern medicine. This study included 110 patients. 79 patients aged 12-18 with menstrual disorders associated with obesity were divided into two groups: group 1: 46 patients with apparent signs of hyperandrogenism, group 2: 33 patients without clinical manifestations of hyperandrogenism. The control group included 31 girls of the same age with a regular menstrual cycle. The complex of hormone examination of adolescent girls included determination of serum content: gonadotropic hormones (luteinizing hormone (LH) and follicle-stimulating hormone (FSH), prolactin (PRL), estradiol (E2), testosterone (T), progesterone (PR), dehydroepiandrosterone sulfate; insulin (In) - radioisotope method on a gamma counter "Narcotest" (reagents "IMMUNOTECH", Czech Republic). We identified hyperleptinemia and leptin resistance in patients with menstrual function impairment associated with obesity. In group I, the adiponectin level exceeded the values of the control group (p<0.05). The results revealed a decrease in A/L in group I - 5.4 times compared with patients in group II (p<0.05) and 4.3 times - compared with the control group (p<0.05). The results revealed a decrease in A/L among girls in the group I with MFI associated with obesity - 4.3 times - compared with girls in the control group (p<0,05).

ADAR1 deficiency protects against high-fat diet-induced obesity and insulin resistance in mice

Obesity is an important independent risk factor for type 2 diabetes, cardiovascular diseases, and many other chronic diseases. The objective of this study was to determine the role of adenosine deaminase acting on RNA 1 (ADAR1) in the development of obesity and insulin resistance. Wild-type (WT) and heterozygous ADAR1-deficient (Adar1+/-) mice were fed normal chow or a high-fat diet (HFD) for 12 wk. Adar1+/- mice fed with HFD exhibited a lean phenotype with reduced fat mass compared with WT controls, although no difference was found under chow diet conditions. Blood biochemical analysis and insulin tolerance test showed that Adar1+/- improved HFD-induced dyslipidemia and insulin resistance. Metabolic studies showed that food intake was decreased in Adar1+/- mice compared with the WT mice under HFD conditions. Paired feeding studies further demonstrated that Adar1+/- protected mice from HFD-induced obesity through decreased food intake. Furthermore, Adar1+/- restored the increased ghrelin expression in the stomach and the decreased serum peptide YY levels under HFD conditions. These data indicate that ADAR1 may contribute to diet-induced obesity, at least partially, through modulating the ghrelin and peptide YY expression and secretion.NEW & NOTEWORTHY This study identifies adenosine deaminase acting on RNA 1 as a novel factor promoting high-fat diet-induced obesity, at least partially, through modulating appetite-related genes ghrelin and PYY.

Sex Differences in Metabolic Recuperation After Weight Loss in High Fat Diet-Induced Obese Mice

Dietary intervention is a common tactic employed to curtail the current obesity epidemic. Changes in nutritional status alter metabolic hormones such as insulin or leptin, as well as the insulin-like growth factor (IGF) system, but little is known about restoration of these parameters after weight loss in obese subjects and if this differs between the sexes, especially regarding the IGF system. Here male and female mice received a high fat diet (HFD) or chow for 8 weeks, then half of the HFD mice were changed to chow (HFDCH) for 4 weeks. Both sexes gained weight (p < 0.001) and increased their energy intake (p < 0.001) and basal glycemia (p < 0.5) on the HFD, with these parameters normalizing after switching to chow but at different rates in males and females. In both sexes HFD decreased hypothalamic NPY and AgRP (p < 0.001) and increased POMC (p < 0.001) mRNA levels, with all normalizing in HFDCH mice, whereas the HFD-induced decrease in ObR did not normalize (p < 0.05). All HFD mice had abnormal glucose tolerance tests (p < 0.001), with males clearly more affected, that normalized when returned to chow. HFD increased insulin levels and HOMA index (p < 0.01) in both sexes, but only HFDCH males normalized this parameter. Returning to chow normalized the HFD-induced increase in circulating leptin (p < 0.001), total IGF1 (p < 0.001), IGF2 (p < 0.001, only in females) and IGFBP3 (p < 0.001), whereas free IGF1 levels remained elevated (p < 0.01). In males IGFBP2 decreased with HFD and normalized with chow (p < 0.001), with no changes in females. Although returning to a healthy diet improved of most metabolic parameters analyzed, fIGF1 levels remained elevated and hypothalamic ObR decreased in both sexes. Moreover, there was sex differences in both the response to HFD and the switch to chow including circulating levels of IGF2 and IGFBP2, factors previously reported to be involved in glucose metabolism. Indeed, glucose metabolism was also differentially modified in males and females, suggesting that these observations could be related.

Sandwich ELISA-Based Electrochemical Biosensor for Leptin in Control and Diet-Induced Obesity Mouse Model

Leptin is a peptide hormone produced primarily in adipose tissues. Leptin is considered a biomarker associated with obesity and obesity-mediated diseases. Biosensor detection of leptin in the blood may play a critical role as an indicator of dynamic pathological changes. In this paper, we introduce an electrochemical biosensor that adopts o-Phenylenediamine (oPD) on screen-printed gold electrodes (SPGEs) for detecting the leptin from a mouse model of diet-induced obesity (DIO). A linear calibration curve for the leptin concentration was obtained in the ranges from 0.1 to 20 ng/mL with a lower detection limit of 0.033 ng/mL. The leptin concentration was quantified with HRP (horseradish peroxidase)-catalyzed oxidation of oPD by two voltammetry methods: cyclic voltammetry (CV) and square-wave voltammetry (SWV). The proposed sandwich enzyme-linked immunosorbent assay (ELISA)-based electrochemical biosensor for the leptin in mouse blood serum showed high stability, sensitivity, selectivity, and effectivity compared to the commercial Leptin ELISA measurement. Thus, we believe that this leptin biosensor can be a sensitive analytical tool to detect low-levels of biomarkers in clinics and point-of-care testing (POCT).

New Actors Driving the Epithelial-Mesenchymal Transition in Cancer: The Role of Leptin

Leptin is a hormone secreted mainly by adipocytes; physiologically, it participates in the control of appetite and energy expenditure. However, it has also been linked to tumor progression in different epithelial cancers. In this review, we describe the effect of leptin on epithelial-mesenchymal transition (EMT) markers in different study models, including in vitro, in vivo, and patient studies and in various types of cancer, including breast, prostate, lung, and ovarian cancer. The different studies report that leptin promotes the expression of mesenchymal markers and a decrease in epithelial markers, in addition to promoting EMT-related processes such as cell migration and invasion and poor prognosis in patients with cancer. Finally, we report that leptin has the greatest biological relevance in EMT and tumor progression in breast, lung, prostate, esophageal, and ovarian cancer. This relationship could be due to the key role played by the enriched tumor microenvironment in adipose tissue. Together, these findings demonstrate that leptin is a key biomolecule that drives EMT and metastasis in cancer.

Acylated Ghrelin as a Multi-Targeted Therapy for Alzheimer's and Parkinson's Disease

Much thought has been given to the impact of Amyloid Beta, Tau and Alpha-Synuclein in the development of Alzheimer's disease (AD) and Parkinson's disease (PD), yet the clinical failures of the recent decades indicate that there are further pathological mechanisms at work. Indeed, besides amyloids, AD and PD are characterized by the culminative interplay of oxidative stress, mitochondrial dysfunction and hyperfission, defective autophagy and mitophagy, systemic inflammation, BBB and vascular damage, demyelination, cerebral insulin resistance, the loss of dopamine production in PD, impaired neurogenesis and, of course, widespread axonal, synaptic and neuronal degeneration that leads to cognitive and motor impediments. Interestingly, the acylated form of the hormone ghrelin has shown the potential to ameliorate the latter pathologic changes, although some studies indicate a few complications that need to be considered in the long-term administration of the hormone. As such, this review will illustrate the wide-ranging neuroprotective properties of acylated ghrelin and critically evaluate the hormone's therapeutic benefits for the treatment of AD and PD.

Meta-analysis of cognitive and behavioral tests in leptin- and leptin receptor-deficient mice

Leptin is a hormone produced by adipocytes that regulates food intake and metabolism. Leptin-related gene-deficient mice, such as db/db and ob/ob mice, are widely used to study diabetes and its related diseases. However, broad effects of leptin appear to cause variability in behavioral test results. We performed a meta-analysis of major behavioral tests in db/db and ob/ob mice. These mice exhibited significant impairments in the Morris water maze, forced swim, novel object recognition, Y-maze, tail suspension, and light-dark box tests, whereas the elevated plus maze and open field tests did not reveal significant changes. We also performed correlation and regression analyses between the animals' performances and the experimental protocols and conditions. The memory-related tests were characterized by the correlations of their results with animal age, while the performances in the elevated plus-maze and forced swim tests were affected by the width of the devices used. In conclusion, db/db and ob/ob mice mainly exhibit memory deficits and depression-like behavior, although experimenters should be aware of animal age and device size in conducting experiments.

[Role of leptin and nuclear receptor PPARγ in PCOS pathogenesis]

Polycystic ovary syndrome (PCOS) is the most common cause of female endocrine infertility. Insulin resistanсе is supposed to be one of the essential factors of this disease pathways. At the same time, the mechanisms of PCOS development in insulin-resistant patients have not been completely established. Leptin and Peroxisome Proliferator-Activated Receptor γ(PPARγ) are involved in carbohydrate metabolism and reproduction function regulation. It indicates that leptin and PPARγ possibly play a role in the pathways of PCOS. This article is a review of publications on this issue. The purpose of this review was to systematize the available information on the molecular mechanisms that determine the role of leptin and PPARγ in the development of PCOS. The literature search was carried out from 04/05/2020 to 05/17/2020 using the scientific literature databases: NCBI PubMed (foreign sources) and Cyberleninka (domestic sources). We analyzed publications for the period 1990-2020.The review presents the current understanding of the possible role of leptin and PPARγ in the regulation of endocrine, immune systems, and reproductive function, as well as in the development of PCOS. Currently, no studies cover the mechanisms of interaction between leptin and PPARγ in the pathways of this syndrome. The available studies indicating the individual contribution and association of leptin and PPARγ with PCOS are conflicting and have many limitations. Therefore, more studies of direct and indirect interaction of leptin and PPARγ, as well as their role in PCOS pathways, are needed.

A review of the relationship between eating behavior, obesity and functional brain network organization

Obesity is a major public health issue affecting nearly 40% of American adults and is associated with increased mortality and elevated risk for a number of physical and psychological illnesses. Obesity is associated with impairments in executive functions such as decision making and inhibitory control, as well as in reward valuation, which is thought to contribute to difficulty sustaining healthy lifestyle behaviors, including adhering to a healthy diet. Growing evidence indicates that these impairments are accompanied by disruptions in functional brain networks, particularly those that support self-regulation, reward valuation, self-directed thinking and homeostatic control. Weight-related differences in task-evoked and resting-state connectivity have most frequently been noted in the executive control network (ECN), salience network (SN) and default mode network (DMN), with obesity generally being associated with weakened connectivity in the ECN and enhanced connectivity in the SN and DMN. Similar disruptions have been observed in the much smaller literature examining the relationship between diet and disordered eating behaviors on functional network organization. The purpose of this narrative review was to summarize what is currently known about how obesity and eating behavior relate to functional brain networks, describe common patterns and provide recommendations for future research based on the identified gaps in knowledge.

Transcriptional regulation of adipogenic marker genes for the improvement of intramuscular fat in Qinchuan beef cattle

The intramuscular fat content plays a crucial role in meat quality traits. Increasing the degree of adipogenesis in beef cattle leads to an increase in the content of intramuscular fat. Adipogenesis a complex biochemical process which is under firm genetic control. Over the last three decades, the Qinchuan beef cattle have been extensively studied for the improvement of meat production and quality traits. In this study, we reviewed the literature regarding adipogenesis and intramuscular fat deposition. Then, we summarized the research conducted on the transcriptional regulation of key adipogenic marker genes, and also reviewed the roles of adipogenic marker genes in adipogenesis of Qinchuan beef cattle. This review will elaborate our understanding regarding transcriptional regulation which is a vital physiological process regulated by a cascade of transcription factors (TFs), key target marker genes, and regulatory proteins. This synergistic action of TFs and target genes ensures the accurate and diverse transmission of the genetic information for the accomplishment of central physiological processes. This information will provide an insight into the transcriptional regulation of the adipogenic marker genes and its role in bovine adipogenesis for the breed improvement programs especially for the trait of intramuscular fat deposition.

Systemic inflammation is negatively associated with early post discharge growth following acute illness among severely malnourished children - a pilot study

Background: Rapid growth should occur among children with severe malnutrition (SM) when medically and nutritionally treated. Systemic inflammation (SI) is associated with death among children with SM and is negatively associated with linear growth. However, the relationship between SI and weight gain during therapeutic feeding following acute illness is unknown. We hypothesised that growth in the first 60 days post-hospital discharge is associated with SI among children with SM. Methods: We conducted secondary analysis of data from HIV-uninfected children with SM (n=98) who survived and were not readmitted to hospital during one year of follow up. We examined the relationship between changes in absolute deficits in weight and mid-upper-arm circumference (MUAC) from enrolment at stabilisation to 60 days later and untargeted plasma proteome, targeted cytokines/chemokines, leptin, and soluble CD14 (sCD14) using multivariate regularized linear regression. Results: The mean change in absolute deficit in weight and MUAC was -0.50kg (standard deviation; SD±0.69) and -1.20cm (SD±0.89), respectively, from enrolment to 60 days later. During the same period, mean weight and MUAC gain was 3.3g/kg/day (SD±2.4) and 0.22mm/day (SD±0.2), respectively. Enrolment inflammatory cytokines interleukin 17 alpha (IL17α), interleukin 2 (IL2), and serum amyloid P (SAP) were negatively associated with weight and MUAC gain. Lipopolysaccharide binding protein (LBP) and complement component 2 were negatively associated with weight gain only. Leptin was positively associated with weight gain. sCD14, beta-2 microglobulin (β2M), and macrophage inflammatory protein 1 beta (MIP1β) were negatively associated with MUAC gain only. Conclusions: Early post-hospital discharge weight and MUAC gain were rapid and comparable to children with uncomplicated SM treated with similar diet in the community. Higher concentrations of SI markers were associated with less weight and MUAC gain, suggesting inflammation negatively impacts recovery from wasting. This finding warrants further research on the role of inflammation on growth among children with SM.

Hypothermic Effect of Acute Citral Treatment during LPS-induced Systemic Inflammation in Obese Mice: Reduction of Serum TNF-α and Leptin Levels

Citral is a mixture of monoterpenes present in the essential oil of several plants, such as Cymbopogon citratus and Zingiber officinale, possessing anti-inflammatory, anti-ulcerogenic, and antipyretic actions. We investigated the action of citral on body temperature (Tb) and inflammatory signaling in eutrophic and obese mice during Systemic Inflammation (SI) induced by Lipopolysaccharide (LPS). Thus, we assessed the effect of citral (25, 100, and 300 mg/kg) and ibuprofen in LPS-induced SI in Swiss male mice fed a standard diet (SD) or high-fat diet (HFD) for 12 weeks. Following SI induction, we measured Tb and collected the serum, hypothalamus, and gastric mucosa for biochemical measurements. Acute treatment with citral decreased the Tb of both SD and HFD-fed animals. Citral (300 mg/kg) treatment caused a significantly lower Tb variation in HFD-fed animals than in those fed the SD. Citral reduced peripheral levels of tumor necrosis factor (TNF)-α in SD and HFD mice and decreased serum leptin concentration in HFD mice 90 min after the LPS challenge. Furthermore, citral also reduced interleukin (IL)-6 levels in the hypothalamus of obese mice. In summary, citral effectively reduced Tb during SI by reducing inflammatory mediators with a distinct action profile in HFD mice when compared with SD.

[Something new in the genetics of monogenic obesity and its insights into pathophysiology]

Obesity is a complex, multifactorial disorder. About 5% of obese patients actually present with a monogenic form of obesity where only one mutation is sufficient to cause the disease. So far, the genes that have been found to be mutated in these monogenic forms play a key role in the leptin/melanocortin pathway which is mainly active in the hypothalamus and which regulates food intake and energy expenditure. Our laboratory has recently reported a novel monogenic form of obesity due to MRAP2 deficiency where, contrary to previously described monogenic forms of obesity, the carriers presented with hyperglycemia and hypertension in addition to obesity, suggesting that MRAP2 might play a pleiotropic role in metabolic tissues, in addition to its role in brain control of food intake and energy expenditure.

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

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

Sex Differences in the Risk of Barrett's Esophagus Associated With the Metabolic Effects of Obesity

GOAL

The goal of this study was to determine if there is an association between the insulin-insulin-like growth factor axis, the metabolic syndrome (MetS), type 2 diabetes mellitus and risk of Barrett's esophagus (BE), and if these associations are modified by sex.

BACKGROUND

BE is more common in males. Gastroesophageal reflux disease, the major risk factor for BE occurs at similar frequencies in both sexes, suggesting that sex-related factors such as the metabolic effects of abdominal obesity may be important in the causation of BE.

MATERIALS AND METHODS

A structured interview, anthropometric measures, and fasting blood were collected within a population-based case-control study. We recruited 227 BE cases (70% male) and 241 population controls, frequency matched by age and sex. We estimated odds ratios (ORs) and 95% confidence intervals (CIs) for association with BE using multivariable logistic regression models.

RESULTS

Hyperinsulinemia (highest vs. lowest tertile, OR=1.9; 95% CI: 1.2-3.1), Homeostatic Model Assessment of Insulin Resistance (OR=1.9; 95% CI: 1.2-3.1) and the MetS (OR=1.8; 95% CI: 1.2-2.6) were independently associated with an increased risk of BE. With each additional MetS criterion, there was a 20% increased risk of BE (OR=1.2; 95% CI: 1.0-1.4). When stratified by sex, these associations were found in males but not females. We found no association with serum measures of insulin-like growth factors or interleukin-6 and risk of BE.

CONCLUSION

Hyperinsulinemia, insulin resistance, and the MetS are associated with the risk of BE in males but not females, suggesting these factors may contribute to the higher prevalence of BE in males.

Preoperative Level of Leptin Can Be a Predictor of Glycemic Control for Patients with Diabetes Undergoing Bariatric Surgery

INTRODUCTION

Bariatric surgery is a first-line treatment for patients with obesity and diabetes. It is uncertain whether leptin has an influence on glycemia in the postoperative period.

METHODS

A cohort study of thirty-eight individuals with obesity and diabetes who underwent laparoscopic Roux-en-Y gastric bypass was undertaken. The levels of leptin, glucose, and glycosylated hemoglobin were verified in the preoperative period and in the first and third postoperative months.

RESULTS

The majority of patients were women (81.6%), and the mean age was 47.3 years (SD 8.8). The mean BMI was reduced by 17.75% (from 47.3 to 38.9 kg/m²) and the mean glycemia by 26.76%. Preoperative leptin had a moderate positive correlation with glucose level at the third month (Pearson r = 0.46, P = 0.02), but not with HbA1c. Patients with leptin above 27.34 ng/mL had a higher glucose level at the end of observation (101.9 versus 88.9, t test, P = 0.042).

CONCLUSION

The search for factors that influence diabetes control after bariatric surgery is of major importance in clinical practice. Our study reported a level of leptin that can predict the prognosis of glycemic control after the intervention. This finding still needs to be validated and confirmed in other populations.

Intranasal Targeting of Hypothalamic PTP1B and TCPTP Reinstates Leptin and Insulin Sensitivity and Promotes Weight Loss in Obesity

The importance of hypothalamic leptin and insulin resistance in the development and maintenance of obesity remains unclear. The tyrosine phosphatases protein tyrosine phosphatase 1B (PTP1B) and T cell protein tyrosine phosphatase (TCPTP) attenuate leptin and insulin signaling and are elevated in the hypothalami of obese mice. We report that elevated PTP1B and TCPTP antagonize hypothalamic leptin and insulin signaling and contribute to the maintenance of obesity. Deletion of PTP1B and TCPTP in the hypothalami of obese mice enhances CNS leptin and insulin sensitivity, represses feeding, and increases browning, to decrease adiposity and improve glucose metabolism. The daily intranasal administration of a PTP1B inhibitor, plus the glucocorticoid antagonist RU486 that decreases TCPTP expression, represses feeding, increases browning, promotes weight loss, and improves glucose metabolism in obese mice. Our findings causally link heightened hypothalamic PTP1B and TCPTP with leptin and insulin resistance and the maintenance of obesity and define a viable pharmacological approach by which to promote weight loss in obesity.

Leptin and Its Derivatives: A Potential Target for Autoimmune Diseases

Leptin is an adipocyte-derived hormone product of the obese (ob) gene. Leptin plays an important regulatory role as an immunomodulatory factor in the maintenance and homeostasis of immune functions. Indeed, the role of leptin as an immunomodulator in inflammatory and immune responses has attracted increasing attention in recent years. Leptin mostly affects responses through the immunomodulation of monocytes, dendritic cells, neutrophils, NK cells, and dendritic cells in addition to modulating T and B cell development and functions. Leptin is also an important inflammatory regulator, wherein higher expression influences the secretion rates of IL-6, C-reactive proteins, and TNF-α. Moreover, leptin is highly involved in processes related to human metabolism, inflammatory reactions, cellular development, and diseases, including hematopoiesis. Owing to its diverse immunerelated functions, leptin has been explored as a potential target for therapeutic development in the treatment of autoimmune diseases.

Leptin, Obesity, and Hypertension: A Review of Pathogenetic Mechanisms

The adipokine leptin is expressed at higher concentrations in obese subjects, who also incidentally have a higher prevalence of hypertension. The pathogenesis of this obesity-related hypertension is controversial and is believed to be related to many factors including increased sympathetic activity, abnormalities of the renin-angiotensin system, sodium retention, and an endotheliopathy acting independently or in concert with increased circulating leptin. This review discusses the potential mechanisms through which changes in leptin signal transduction pathways in tissues with the leptin receptor, especially the hypothalamus, mediate the pathogenetic relationships between obesity and hypertension. The hypothesis is explored that leptin effects on blood pressure (BP) are meditated by the downstream effects of hypothalamic leptin signaling and ultimately result in activation of specific melanocortin receptors located on sympathetic neurons in the spinal cord. The physiological consequences of this sympathetic activation of the heart and kidney are activation of the renin-angiotensin system, sodium retention and circulatory expansion and finally, elevated BP. This sequence of events has been elegantly demonstrated with leptin infusion and gene knockout studies in animal models but has not been convincingly reproducibly confirmed in humans. Further studies in human subjects on the specific roles of hypothalamic leptin in essential hypertension are indicated as elucidation of the signaling pathways should provide better understanding of the role of weight loss in BP control and afford an additional mechanism for pharmacologic control of BP in adults and children at risk of cardiovascular disease.

Aquaporin 7 involved in GINSENOSIDE-RB1-mediated anti-obesity via peroxisome proliferator-activated receptor gamma pathway

Background

Obesity, characterized by the excessive accumulation of triglycerides in adipocytes and their decreased excretion from adipocytes, is closely related to various health problems. Ginsenoside Rb1 (Rb1), the most active component of the traditional Chinese medicine ginseng, has been reported to have positive effects on lipid metabolism. The aim of the present study was to determine the protective effects of Rb1 on glycolipid metabolism under obesity conditions and its mechanisms and to reveal the signaling pathways involved.

Methods

In our study, male C57BL/6 mice with obesity induced by a high-fat diet (HFD) and mature 3 T3-L1 adipocytes were used to investigate the role of Rb1 in lipid accumulation and explore its possible molecular mechanism in vivo and in vitro, respectively.

Results

Rb1 reduced the body weight, fat mass, adipocytes size and serum free fatty acid (FFA) concentration of obese mice. In differentiated 3 T3-L1 adipocytes, Rb1 reduced the accumulation of lipid droplets and stimulated output of triglycerides. Additionally, the expression of peroxisome proliferator-activated receptor gamma (PPARγ), phosphorylated PPARγ (Ser112) and aquaporin 7 (AQP7) was upregulated in adipocytes and adipose tissues upon Rb1 treatment. However, intervention of GW9662, PPARγ antagonist, attenuated Rb1-mediated effects on glycolipid metabolism and AQP7 levels.

Conclusions

These data indicated that Rb1 reduced body weight and improved glycolipid metabolism by upregulating PPARγ and AQP7 protein levels. Our study indicated a potential role for Rb1 in the prevention and treatment of obesity.

There and Back Again: Leptin Actions in White Adipose Tissue

Leptin is a hormone discovered almost 30 years ago with important implications in metabolism. It is primarily produced by white adipose tissue (WAT) in proportion to the amount of fat. The discovery of leptin was a turning point for two principle reasons: on one hand, it generated promising expectations for the treatment of the obesity, and on the other, it changed the classical concept that white adipose tissue was simply an inert storage organ. Thus, adipocytes in WAT produce the majority of leptin and, although its primary role is the regulation of fat stores by controlling lipolysis and lipogenesis, this hormone also has implications in other physiological processes within WAT, such as apoptosis, browning and inflammation. Although a massive number of questions related to leptin actions have been answered, the necessity for further clarification facilitates constantly renewing interest in this hormone and its pathways. In this review, leptin actions in white adipose tissue will be summarized in the context of obesity.

Leptin reduces in vitro cementoblast mineralization and survival as well as induces PGE2 release by ERK1/2 commitment

Objectives

Juvenile obesity is a complex clinical condition that is present more and more frequently in the daily orthodontic practice. Over-weighted patients have an impaired bone metabolism, due in part to their increased levels of circulating adipokines. Particularly, leptin has been reported to play a key role in bone physiology. Leptin is ubiquitously present in the body, including blood, saliva, and crevicular fluid. If, and to what extent, it could influence the reaction of cementoblasts during orthodontic-induced forces is yet unknown.

Material and methods

OCCM-30 cementoblasts were cultivated under compressive forces using different concentrations of leptin. The expression of ObR, Runx-2, Osteocalcin, Rank-L, Sost, Caspase 3, 8, and 9 were analyzed by RT-PCR. Western blots were employed for protein analysis. The ERK1/2 antagonist FR180204 (Calbiochem) was used and cPLA2 activation, PGE2, and cytochrome C release were further evaluated.

Results

In vitro, when compressive forces are applied, leptin promotes ERK1/2 phosphorylation, as well as upregulates PGE2 and caspase 3 and caspase 9 on OCCM cells. Blockade of ERK1/2 impairs leptin-induced PGE2 secretion and reduced caspase 3 and caspase 9 expression.

Conclusions

Leptin influences the physiological effect of compressive forces on cementoblasts, exerting in vitro a pro-inflammatory and pro-apoptotic effect.

Clinical relevance

Our findings indicate that leptin exacerbates the physiological effect of compressive forces on cementoblasts promoting the release of PGE2 and increases the rate of cell apoptosis, and thus, increased levels of leptin may influence the inflammatory response during orthodontically induced tooth movement.

Role of Leptin in Inflammation and Vice Versa

Inflammation is an essential immune response for the maintenance of tissue homeostasis. In a general sense, acute and chronic inflammation are different types of adaptive response that are called into action when other homeostatic mechanisms are insufficient. Although considerable progress has been made in understanding the cellular and molecular events that are involved in the acute inflammatory response to infection and tissue injury, the causes and mechanisms of systemic chronic inflammation are much less known. The pathogenic capacity of this type of inflammation is puzzling and represents a common link of the multifactorial diseases, such as cardiovascular diseases and type 2 diabetes. In recent years, interest has been raised by the discovery of novel mediators of inflammation, such as microRNAs and adipokines, with different effects on target tissues. In the present review, we discuss the data emerged from research of leptin in obesity as an inflammatory mediator sustaining multifactorial diseases and how this knowledge could be instrumental in the design of leptin-based manipulation strategies to help restoration of abnormal immune responses. On the other direction, chronic inflammation, either from autoimmune or infectious diseases, or impaired microbiota (dysbiosis) may impair the leptin response inducing resistance to the weight control, and therefore it may be a cause of obesity. Thus, we are reviewing the published data regarding the role of leptin in inflammation, and the other way around, the role of inflammation on the development of leptin resistance and obesity.

The Thousand Faces of Leptin in the Lung

Leptin is a pleotropic hormone known to regulate a wide range of systemic functions, from satiety to inflammation. Increasing evidence has shown that leptin and its receptor (ObR) are not only expressed in adipose tissue but also in several organs, including the lungs. Leptin levels were first believed to be elevated only in the lungs of obese patients, and leptin was suspected to be responsible for obesity-related lung complications. Aside from obesity, leptin displays many faces in the respiratory system, independently of body weight, as this cytokine-like hormone plays important physiological roles, from the embryogenic state to maturation of the lungs and the control of ventilation. The leptin-signaling pathway is also involved in immune modulation and cell proliferation, and its dysregulation can lead to the onset of lung diseases. This review article addresses the thousand faces of leptin and its signaling in the lungs under physiological conditions and in disease.

Endocrine Mechanisms Connecting Exercise to Brown Adipose Tissue Metabolism: a Human Perspective

PURPOSE OF REVIEW

To summarize the state-of-the-art regarding the exercise-regulated endocrine signals that might modulate brown adipose tissue (BAT) activity and/or white adipose tissue (WAT) browning, or through which BAT communicates with other tissues, in humans.

RECENT FINDINGS

Exercise induces WAT browning in rodents by means of a variety of physiological mechanism. However, whether exercise induces WAT browning in humans is still unknown. Nonetheless, a number of protein hormones and metabolites, whose signaling can influence thermogenic adipocyte's metabolism, are secreted during and/or after exercise in humans from a variety of tissues and organs, such as the skeletal muscle, the adipose tissue, the liver, the adrenal glands, or the cardiac muscle. Overall, it seems plausible to hypothesize that, in humans, exercise secretes an endocrine cocktail that is likely to induce WAT browning, as it does in rodents. However, even if exercise elicits a pro-browning endocrine response, this might result in a negligible effect if blood flow is restricted in thermogenic adipocyte-rich areas during exercise, which is still to be determined. Future studies are needed to fully characterize the exercise-induced secretion (i.e., to determine the effect of the different exercise frequency, intensity, type, time, and volume) of endocrine signaling molecules that might modulate BAT activity and/or WAT browning or through which BAT communicates with other tissues, during exercise. The exercise effect on BAT metabolism and/or WAT browning could be one of the still unknown mechanisms by which exercise exerts beneficial health effects, and it might be pharmacologically mimicked.

Carotid Body and Metabolic Syndrome: Mechanisms and Potential Therapeutic Targets

The carotid body (CB) is responsible for the peripheral chemoreflex by sensing blood gases and pH. The CB also appears to act as a peripheral sensor of metabolites and hormones, regulating the metabolism. CB malfunction induces aberrant chemosensory responses that culminate in the tonic overactivation of the sympathetic nervous system. The sympatho-excitation evoked by CB may contribute to the pathogenesis of metabolic syndrome, inducing systemic hypertension, insulin resistance and sleep-disordered breathing. Several molecular pathways are involved in the modulation of CB activity, and their pharmacological manipulation may lead to overall benefits for cardiometabolic diseases. In this review, we will discuss the role of the CB in the regulation of metabolism and in the pathogenesis of the metabolic dysfunction induced by CB overactivity. We will also explore the potential pharmacological targets in the CB for the treatment of metabolic syndrome.

Leptin induces a contracting effect on guinea pig tracheal smooth muscle via the Ob-R receptor mechanism: novel evidence

The purpose of this study was to explore the potential contracting effect of leptin on isolated guinea pig tracheal smooth muscle (TSM), the possible mechanism, and the impact of epithelium denudation or allergen sensitization, respectively. An in vitro experiment investigated the effect of leptin at a concentration of 250-1000 nmol/L on isolated guinea pig TSM with an intact or denuded epithelium. Ovalbumin and IgE were used to test the impact of active and passive sensitization. The isolated TSM strips were incubated in Krebs solution and aerated with carbogen (95% O₂ and 5% CO₂) via an automated tissue organ bath system (n = 4 for each group). Isometric contractions were recorded digitally using iox2 data acquisition software. The possible mechanism of leptin-induced TSM contraction was examined by preincubation with leptin receptor (Ob-R) antagonist. Leptin had significant concentration-dependent contraction effects on guinea pig TSM (p < 0.05). Epithelium denuding and active or passive sensitization significantly increased the potency of the leptin. Preincubation with a leptin receptor (Ob-R) antagonist significantly reduced the contraction effects, suggesting an Ob-R-mediated mechanism. Leptin had a contracting effect on airway smooth muscles potentiated by either epithelium denuding or sensitization, and the Ob-R mechanism was a possible effect mediator.

Obesity, the most common comorbidity in SARS-CoV-2: is leptin the link?

Overweight and obesity are major risk factors for diabetes, cardiovascular disease, and lung disease. These diseases are the most commonly reported health conditions that predispose individuals with SARS-CoV-2 infection to require hospitalization including intensive care unit admissions. The innate immune response is the host’s first line of defense against a human coronavirus infection. However, most coronaviruses are armed with one strategy or another to overcome host antiviral defense, and the pathogenicity of the virus is related to its capacity to suppress host immunity. The multifaceted nature of obesity including its effects on immunity can fundamentally alter the pathogenesis of acute respiratory distress syndrome and pneumonia, which are the major causes of death due to SARS-CoV-2 infection. Elevated circulating leptin concentrations are a hallmark of obesity, which is associated with a leptin-resistant state. Leptin is secreted by adipocytes in proportion to body fat and regulates appetite and metabolism through signaling in the hypothalamus. However, leptin also signals through the Jak/STAT and Akt pathways, among others, to modulate T cell number and function. Thus, leptin connects metabolism with the immune response. Therefore, it seems appropriate that its dysregulation would have serious consequences during an infection. We propose that leptin may be the link between obesity and its high prevalence as a comorbidity of the SARS-CoV-2 infection. In this article, we present a synthesis of the mechanisms underpinning susceptibility to respiratory viral infections and the contribution of the immunomodulatory effects of obesity to the outcome.

Role of Skeletal Muscle in Insulin Resistance and Glucose Uptake

The skeletal muscle is the largest organ in the body, by mass. It is also the regulator of glucose homeostasis, responsible for 80% of postprandial glucose uptake from the circulation. Skeletal muscle is essential for metabolism, both for its role in glucose uptake and its importance in exercise and metabolic disease. In this article, we give an overview of the importance of skeletal muscle in metabolism, describing its role in glucose uptake and the diseases that are associated with skeletal muscle metabolic dysregulation. We focus on the role of skeletal muscle in peripheral insulin resistance and the potential for skeletal muscle-targeted therapeutics to combat insulin resistance and diabetes, as well as other metabolic diseases like aging and obesity. In particular, we outline the possibilities and pitfalls of the quest for exercise mimetics, which are intended to target the molecular mechanisms underlying the beneficial effects of exercise on metabolic disease. We also provide a description of the molecular mechanisms that regulate skeletal muscle glucose uptake, including a focus on the SNARE proteins, which are essential regulators of glucose transport into the skeletal muscle. © 2020 American Physiological Society. Compr Physiol 10:785-809, 2020.

Differential effect of high-fat, high-sucrose and combined high-fat/high-sucrose diets consumption on fat accumulation, serum leptin and cardiac hypertrophy in rats

The consumption of high calorie-content diets is the first cause of obesity, probably the main health issue worldwide; however, the experimental evidences for evaluating the differential metabolic modifications of high-sucrose or high-fat diets are scare. We evaluated the metabolic outcomes of the obesity induced by the chronic consumption of high-sucrose (HS), high-fat (HF) or combined diets (HSHF), among the effect on the development of cardiac hypertrophy in Wistar rats. Rats from the HS, HF, and HSHS groups developed moderate obesity. Only the HS group showed increased triglycerides levels after four months. Increased leptin levels were observed in HS and HF groups without changes on cardiac hypertrophy; on the opposing, HSHF group presented hypertrophy without the changes in serum leptin. The three experimental groups showed a decreased expression of leptin receptors ObR-b. In our results, the kind of diet for the induction of obesity is relevant for the outcome of the pathological profile.

The association between leptin and adiponectin, and metabolic syndrome components and serum levels of lipid peroxidation in bipolar disorder patients treated with lithium and valproic acid

BACKGROUND

The aim of study is to assess a relation between the adiponectin and leptin levels, and metabolic syndrome components and lipid peroxidation treated with Li and VPA in bipolar disorder patients and compared with controls.

MATERIALS AND METHODS

56 patients and 31 healthy controls were enrolled. The ATP III criteria were used to determine metabolic syndrome components. Leptin, adiponectin, lipid peroxidation and lipid profiles were measured.

RESULTS

Malondialdehyde in Li patients was higher than VPA patients. BMI, waist circumference (WC), triglyceride, malondialdehyde and adiponectin levels were increased, whereas HDL-cholesterol (VPA treated patients) and leptin were decreased in patients compared with controls. Leptin and adiponectin were correlated with WC, triglyceride and malondialdehyde in both groups. Adiponectin was correlated with HDL-cholesterol in VPA patients.

CONCLUSION

Patients should be checked metabolic syndrome components, serum leptin and adiponectin level occasionally to prevent possible deficiency or pathologic increase of these parameters.

Differential Expression of Ormdl Genes in the Islets of Mice and Humans with Obesity

The orosomucoid-like (Ormdl) proteins play a critical role in sphingolipid homeostasis, inflammation, and ER stress, all of which are associated with obesity and βcell dysfunction. However, their roles in β cells and obesity remain unknown. Here, we show that islets from overweight/obese human donors displayed marginally reduced ORMDL1-2 expression, whereas ORMDL3 expression was significantly downregulated compared with islets from lean donors. In contrast, Ormdl3 was substantially upregulated in the islets of leptin-deficient obese (ob/ob) mice compared with lean mice. Treatment of ob/ob mice and their islets with leptin markedly reduced islet Ormld3 expression. Ormdl3 knockdown in a β cell line induced expression of pro-apoptotic markers, which was rescued by ceramide synthase inhibitor fumonisin B1. Our results reveal differential expression of Ormdl3 in the islets of a mouse model and humans with obesity, highlight the potential effect of leptin in this differential regulation, and suggest a role for Ormdl3 in β cell apoptosis.

•

Islets of overweight/obese human donors display markedly reduced ORMDL3 expression

•

Ormdl3 expression was significantly upregulated in the islets of ob/ob mice

•

Leptin treatment markedly reduced Ormld3 expression in the islets of ob/ob mice

•

Fumonisin B1 restores increased apoptotic marker levels induced by Ormdl3 silencing

Precision Nutrition and Childhood Obesity: A Scoping Review

Environmental exposures such as nutrition during life stages with high developmental plasticity-in particular, the in utero period, infancy, childhood, and puberty-may have long-lasting influences on risk of chronic diseases, including obesity-related conditions that manifest as early as childhood. Yet, specific mechanisms underlying these relationships remain unclear. Here, we consider the study of 'omics mechanisms, including nutrigenomics, epigenetics/epigenomics, and metabolomics, within a life course epidemiological framework to accomplish three objectives. First, we carried out a scoping review of population-based literature with a focus on studies that include 'omics analyses during three sensitive periods during early life: in utero, infancy, and childhood. We elected to conduct a scoping review because the application of multi-'omics and/or precision nutrition in childhood obesity prevention and treatment is relatively recent, and identifying knowledge gaps can expedite future research. Second, concomitant with the literature review, we discuss the relevance and plausibility of biological mechanisms that may underlie early origins of childhood obesity identified by studies to date. Finally, we identify current research limitations and future opportunities for application of multi-'omics in precision nutrition/health practice.