Appetite and energy balance signals from adipocytes

Effects of Ramadan intermittent fasting on hormones regulating appetite in healthy individuals: A systematic review and meta-analysis

BACKGROUND AND AIMS

This systematic review and meta-analysis aimed to examine the effect of Ramadan intermittent fasting on appetite-regulating hormones including leptin, ghrelin, insulin, gastrin, glucagon-like peptide-1, peptide YY, and cholecystokinin.

METHODS

We searched the MEDLINE, Embase, Cochrane Library, CINAHL, Google Scholar, and Web of Science databases to identify relevant research on appetite-regulating hormones during Ramadan intermittent fasting, published until the end of March 2024.

RESULTS

Data from 16 eligible studies comprising 664 participants (341, 51.4 % male) with a mean ± standard deviation age of 33.9 ± 10.8 years were included. The meta-analysis included 12 studies with complete leptin data, showing no significant effect of Ramadan intermittent fasting on leptin concentrations (standardised mean difference - SMD = -0.11 μg/mL, 95 % CI: -0.36 to 0.14). Analysis of three studies with complete ghrelin data demonstrated a significant increase in ghrelin concentrations following Ramadan intermittent fasting (SMD = 0.31 pg/mL, 95 % CI: 0.03 to 0.60). Six studies examining insulin concentrations pre- and post-fasting revealed no significant effect on insulin concentrations (SMD = -0.24 μU/mL, 95 % CI: -0.54 to 0.02). Similarly, analysis of three studies with complete gastrin data showed no significant effect of intermittent fasting on gastrin concentrations (SMD = 0.23 pg/mL, 95 % CI: -0.71 to 0.99).

CONCLUSION

Ramadan intermittent fasting significantly increases ghrelin concentrations while showing no significant effects on leptin, insulin, and gastrin. While ghrelin findings were consistent across studies, the high heterogeneity in leptin studies suggests further research to better understand the effects of Ramadan intermittent fasting on appetite-regulating hormones.

Metabolic, Inflammatory, and Molecular Impact of Cancer Cachexia on the Liver

Cancer-associated cachexia (CAC) is a severe wasting syndrome, marked by involuntary weight loss and muscle wasting. It is a leading cause of cancer-related morbidity and mortality, and is driven by systemic, chronic low-grade inflammation. Key cytokines, such as IL-6 and GDF15, activate catabolic pathways in many organs. This study examined the role of inflammation and metabolic disruption in the liver during CAC, focusing on its dual role as both a target and a source of inflammatory factors. The analysis covered protein and lipid metabolism disturbances, including the hepatic production of acute-phase proteins and insulin resistance. Hepatic inflammation contributes to systemic dysfunction in CAC. The increased production of C-Reactive Protein (CRP) impacts muscle wasting, while liver inflammation leads to insulin resistance and hepatic steatosis, aggravating the cachectic state. Therefore, understanding the molecular mechanisms of liver metabolism in CAC is essential for developing effective therapies. Potential interventions include anti-inflammatory treatments, anabolic strategies, and restoration of lipid metabolism. Further research is necessary to explore the liver's full contribution to CAC and its systemic effects, allowing to the development of liver-targeted therapeutic strategies.

Mechanisms of cancer cachexia and targeted therapeutic strategies

Tumor cachexia is a multifactorial syndrome characterized by systemic dysfunction, including anorexia and severe weight loss that is resistant to standard nutritional interventions. It is estimated that approximately 20 % of cancer patients succumb to cachexia in the later stages of their disease. Thus, understanding its pathogenesis is vital for improving therapeutic outcomes. Recent research has focused on the imbalance between energy intake and expenditure in cachexia. Clinically, cachexia presents with anorexia, adipose tissue atrophy, and skeletal muscle wasting, each driven by distinct mechanisms. Anorexia arises primarily from tumor-secreted factors and cancer-induced hormonal disruptions that impair hypothalamic regulation of appetite. Adipose tissue atrophy is largely attributed to enhanced lipolysis, driven by increased activity of enzymes such as adipose triglyceride lipase and hormone-sensitive lipase, coupled with decreased lipoprotein lipase activity. The browning of white adipose tissue, facilitated by uncoupling protein 1, further accelerates fat breakdown by increasing energy expenditure. Skeletal muscle atrophy, a hallmark of cachexia, results from dysregulated protein turnover via the ubiquitin-proteasome and autophagy-lysosomal pathways, as well as mitochondrial dysfunction. Additionally, chemotherapy can exacerbate cachexia. This review examines the molecular mechanisms underlying cancer cachexia and discusses current therapeutic strategies, aiming to inform future research and improve treatment approaches.

Personalizing Nutrition Strategies: Bridging Research and Public Health

In recent years, although life expectancy has increased significantly, non-communicable diseases (NCDs) continue to pose a significant threat to the health of the global population. Therefore, eating habits have been recognized as key modifiable factors that influence people's health and well-being. For this reason, it is interesting to study dietary patterns, since the human diet is a complex mixture of macronutrients, micronutrients, and bioactive compounds, and can modulate multiple physiological processes, including immune function, the metabolism, and inflammation. To ensure that the data we acquired were current and relevant, we searched primary and secondary sources, including scientific journals, bibliographic indexes, and databases in the last 15 years with the most relevant articles. After this search, we observed that all the recent research on NCDs suggests that diet is a critical factor in shaping an individual's health outcomes. Thus, cardiovascular, metabolic, mental, dental, and visual health depends largely on the intake, habits and patterns, and nutritional behaviors. A diet high in processed and refined foods, added sugars, and saturated fats can increase the risk of developing chronic diseases. On the other hand, a diet rich in whole, nutrient-dense foods, such as vegetables, fruits, nuts, legumes, and a high adherence to Mediterranean diet can improve health's people.

Chemotherapy-induced gastrointestinal toxicity: Pathogenesis and current management

Chemotherapy is the most common treatment for malignant tumors. However, chemotherapy-induced gastrointestinal toxicity (CIGT) has been a major concern for cancer patients, which reduces their quality of life and leads to treatment intolerance and even cessation. Nevertheless, prevention and treatment for CIGT are challenging, due to the prevalence and complexity of the condition. Chemotherapeutic drugs directly damage gastrointestinal mucosa to induce CIGT, including nausea, vomiting, anorexia, gastrointestinal mucositis, and diarrhea, etc. The pathogenesis of CIGT involves multiple factors, such as gut microbiota disorders, inflammatory responses and abnormal neurotransmitter levels, that synergistically contribute to its occurrence and development. In particular, the dysbiosis of gut microbiota is usually linked to abnormal immune responses that increases inflammatory cytokines' expression, which is a common characteristic of many types of CIGT. Chemotherapy-induced intestinal neurotoxicity is also a vital concern in CIGT. Currently, modern medicine is the dominant treatment of CIGT, however, traditional Chinese medicine (TCM) has attracted interest as a complementary and alternative therapy that can greatly alleviate CIGT. Accordingly, this review aimed to comprehensively summarize the pathogenesis and current management of CIGT using PubMed and Google Scholar databases, and proposed that future research for CIGT should focus on the gut microbiota, intestinal neurotoxicity, and promising TCM therapies, which may help to develop more effective interventions and optimize managements of CIGT.

Excess glucose or fat differentially affects metabolism and appetite-related gene expression during zebrafish embryogenesis

Zebrafish embryos use their yolk sac reserve as the sole nutrient source during embryogenesis. The two main forms of energy fuel can be found in the form of glucose or fat. Zebrafish embryos were exposed to glucose or injected with free fatty acid/Triacylglycerol (FFA/TAG) into the yolk sac at 24 hpf. At 72 hpf, glucose exposed or FFA/TAG injected had differential effects on gene expression in embryos, with fat activating lipolysis and β-oxidation and glucose activating the insulin pathway. Bulk RNA-seq revealed that more gene expression was affected by glucose exposure compared to FFA/TAGs injection. Appetite-controlling genes were also differently affected by glucose exposure or FFA/TAG injections. Because the embryo did not yet feed itself at the time of our analysis, gene expression changes occurred in absence of actual hunger and revealed how the embryo manages its nutrient intake before active feeding.

Neuroendocrine and neuroimmune mechanisms underlying comorbidity of pain and obesity

Pain and obesity, as well as their associated impairments, are major health concerns. Understanding the relationship between the two is the focus of a growing body of research. However, early researches attribute increased mechanical stress from excessive weight as the main factor of obesity-related pain, which not only over-simplify the association, but also fail to explain some controversial outcomes arising from clinical investigations. This review focuses on neuroendocrine and neuroimmune modulators importantly involved in both pain and obesity, analyzing nociceptive and anti-nociceptive mechanisms based on neuroendocrine pathways including galanin, ghrelin, leptin and their interactions with other neuropeptides and hormone systems which have been reported to play roles in pain and obesity. Mechanisms of immune activities and metabolic alterations are also discussed, due to their intense interactions with neuroendocrine system and crucial roles in the development and maintenance of inflammatory and neuropathic pain. These findings have implications for health given rising rates of obesity and pain-related diagnoses, by providing novel weight-control and analgesic therapies targeted on specific pathways.

The Fidget Factor and the obesity paradox. How small movements have big impact

The hypothesis is that the Fidget Factor is the innate neurological pulse that propels humans and other species to move to support their health. Fidgets, previously thought to be spontaneous, are neurologically regulated and highly ordered (non-random). Modern societies being chair-based overwhelm Fidget Factor pulses and consequently inflict chair-based living for transportation, labor, and leisure. Despite impulses firing through the nervous system, people sit because environmental design overwhelms the biology. Urbanization and chair-based societies were designed after the industrial revolution to promote productivity; however, the consequence has been opposite. Crushing the natural urge to move—the Fidget Factor—is a public health calamity. Excess sitting is associated with a myriad of detrimental health consequences and impairs productivity. Fidgeting may reduce all-cause mortality associated with excessive sitting. The Fidget Factor offers hope; data demonstrate that workplaces and schools can be designed to promote activity and free people's Fidget Factors. Evidence shows that people are happier, healthier, wealthier, and more successful if their Fidget Factors are freed.

The Role of Crosstalk between Adipose Cells and Myocytes in the Pathogenesis of Sarcopenic Obesity in the Elderly

As a result of aging, body composition changes, with a decline in muscle mass and an increase in adipose tissue (AT), which reallocates from subcutaneous to visceral depots and stores ectopically in the liver, heart and muscles. Furthermore, with aging, muscle and AT, both of which have recognized endocrine activity, become dysfunctional and contribute, in the case of positive energy balance, to the development of sarcopenic obesity (SO). SO is defined as the co-existence of excess adiposity and low muscle mass and function, and its prevalence increases with age. SO is strongly associated with greater morbidity and mortality. The pathogenesis of SO is complex and multifactorial. This review focuses mainly on the role of crosstalk between age-related dysfunctional adipose and muscle cells as one of the mechanisms leading to SO. A better understanding of this mechanisms may be useful for development of prevention strategies and treatments aimed at reducing the occurrence of SO.

Insight on the Role of Leptin: A Bridge from Obesity to Breast Cancer

Leptin is a peptide hormone, mainly known for its role as a mediator of adipose tissue endocrine functions, such as appetite control and energy homeostasis. In addition, leptin signaling is involved in several physiological processes as modulation of innate and adaptive immune responses and regulation of sex hormone levels. When adipose tissue expands, an imbalance of adipokines secretion may occur and increasing leptin levels contribute to promoting a chronic inflammatory state, which is largely acknowledged as a hallmark of cancer. Indeed, upon binding its receptor (LEPR), leptin activates several oncogenic pathways, such as JAK/STAT, MAPK, and PI3K/AKT, and seems to affect cancer immune response by inducing a proinflammatory immune polarization and eventually enhancing T-cell exhaustion. In particular, obesity-associated hyperleptinemia has been related to breast cancer risk development, although the underlying mechanism is yet to be completely clarified and needs to be deemed in light of multiple variables, such as menopausal state and immune response. The aim of this review is to provide an overview of the potential role of leptin as a bridge between obesity and breast cancer and to establish the physio-pathological basis of the linkage between these major health concerns in order to identify appropriate and novel therapeutic strategies to adopt in daily clinical practice.

Influence of Training and Single Exercise on Leptin Level and Metabolism in Obese Overweight and Normal-Weight Women of Different Age

Leptin is one of the important hormones secreted by adipose tissue. It participates in the regulation of energy processes in the body through central and peripheral mechanisms. The aim of this study was to analyse the anthropological and physical performance changes during 9 month training in women of different age and body mass. The additional aim was the analysis of leptin levels in the fasting stage and after a control exercise. Obese (O), overweight (OW), and normal-weight (N) women participated in the study. Additional subgroups of premenopausal (PRE) (<50 years) and postmenopausal (POST) (50+) women were created for leptin level analysis. The main criterion of the division into subgroups was the age of menopause in the population. The control submaximal test and maximal oxygen uptake (VO_2max) according to Astrand-Rhyming procedures was performed at baseline and after 3, 6, and 9 months. Before each control test, body weight (BM), body mass index (BMI), percentage of adipose tissue (% FAT), and mass (FAT (kg)) were measured. Moreover, before and after each test, leptin level was measured. After 9 months, there was a significant decrease in BM in the O (p < 0.05) and OW (p < 0.05) groups with no significant changes in the N group. There was a decrease in BMI in both the O (p < 0.05) and the OW (p < 0.05) groups, with no changes in the N group. The % FAT reduction was noted only in the O group (p < 0.05). VO_2max increased in each of the measured groups (p < 0.05). The fasting leptin level at 0, 3, 6, and 9 months were the highest in the O group. The fasting leptin level before training was highest in the O group compared to the OW group (p < 0.01) and the N group (p < 0.01). It was also higher in the OW group compared to the N group at baseline (0) (p < 0.01) and after 3 and 6 months (p < 0.01). After 9 months, the leptin concentration decreased by 20.2% in the O group, 40.7% in the OW group, and 33% in the N group. Moreover, the fasting leptin level was higher in the POST subgroup compared to the PRE group in the whole group of women (p < 0.05). After a single exercise, the level of leptin in the whole study group decreased (p < 0.05). This was clearly seen, especially in the POST group. The 9 month training had a reducing effect on the blood leptin concentration in groups O, OW, and N. This may have been a result of weight loss and the percentage of fat in the body, as well as systematically disturbed energy homeostasis.

Regulation of Adipose Tissue Biology by Long-Chain Fatty Acids: Metabolic Effects and Molecular Mechanisms

Long-chain fatty acids (LCFA) modulate metabolic, oxidative, and inflammatory responses, and the physiological effects of LCFA are determined by chain length and the degree of saturation. Adipose tissues comprise multiple cell types, and play a significant role in energy storage and expenditure. Fatty acid uptake and oxidation are the pathways through which fatty acids participate in the regulation of energy homeostasis, and their dysregulation can lead to the development of obesity and chronic obesity-related disorders, including type 2 diabetes, cardiovascular diseases, and certain types of cancer. Numerous studies have reported that many aspects of adipose tissue biology are influenced by the number and position of double bonds in LCFA, and these effects are mediated by various signaling pathways, including those regulating adipocyte differentiation (adipogenesis), thermogenesis, and inflammation in adipose tissue. This review aims to describe the underlying molecular mechanisms by which different types of LCFA influence adipose tissue metabolism, and to further clarify their relevance to metabolic dysregulation associated with obesity. A better understanding of the effects of LCFA on adipose tissue metabolism may lead to improved nutraceutical strategies to address obesity and obesity-associated diseases.

Beta-Hydroxybutyrate Suppresses Hepatic Production of the Ghrelin Receptor Antagonist LEAP2

INTRODUCTION

Liver-expressed antimicrobial peptide-2 (LEAP2) is an endogenous ghrelin receptor antagonist, which is upregulated in the fed state and downregulated during fasting. We hypothesized that the ketone body beta-hydroxybutyrate (BHB) is involved in the downregulation of LEAP2 during conditions with high circulating levels of BHB.

METHODS

Hepatic and intestinal Leap2 expression were determined in 3 groups of mice with increasing circulating levels of BHB: prolonged fasting, prolonged ketogenic diet, and oral BHB treatment. LEAP2 levels were measured in lean and obese individuals, in human individuals following endurance exercise, and in mice after BHB treatment. Lastly, we investigated Leap2 expression in isolated murine hepatocytes challenged with BHB.

RESULTS

We confirmed increased circulating LEAP2 levels in individuals with obesity compared to lean individuals. The recovery period after endurance exercise was associated with increased plasma levels of BHB levels and decreased LEAP2 levels in humans. Leap2 expression was selectively decreased in the liver after fasting and after exposure to a ketogenic diet for 3 weeks. Importantly, we found that oral administration of BHB increased circulating levels of BHB in mice and decreased Leap2 expression levels and circulating LEAP2 plasma levels, as did Leap2 expression after direct exposure to BHB in isolated murine hepatocytes.

CONCLUSION

From our data, we suggest that LEAP2 is downregulated during different states of energy deprivation in both humans and rodents. Furthermore, we here provide evidence that the ketone body, BHB, which is highly upregulated during fasting metabolism, directly downregulates LEAP2 levels. This may be relevant in ghrelin receptor-induced hunger signaling during energy deprivation.

Emerging Roles of Non-Coding RNAs in the Feed Efficiency of Livestock Species

A global population of already more than seven billion people has led to an increased demand for food and water, and especially the demand for meat. Moreover, the cost of feed used in animal production has also increased dramatically, which requires animal breeders to find alternatives to reduce feed consumption. Understanding the biology underlying feed efficiency (FE) allows for a better selection of feed-efficient animals. Non-coding RNAs (ncRNAs), especially micro RNAs (miRNAs) and long non-coding RNAs (lncRNAs), play important roles in the regulation of bio-logical processes and disease development. The functions of ncRNAs in the biology of FE have emerged as they participate in the regulation of many genes and pathways related to the major FE indicators, such as residual feed intake and feed conversion ratio. This review provides the state of the art studies related to the ncRNAs associated with FE in livestock species. The contribution of ncRNAs to FE in the liver, muscle, and adipose tissues were summarized. The research gap of the function of ncRNAs in key processes for improved FE, such as the nutrition, heat stress, and gut–brain axis, was examined. Finally, the potential uses of ncRNAs for the improvement of FE were discussed.

Cytokines in the blood of patients with type 2 diabetes mellitus depending on the level of overweight/obesity (literature review and own data)

The paper analyzes the current literature data and the results of our own researches concerning the state of the cytokine network: pro- and anti-inflammatory cytokines (interleukin (IL)1α, IL-1β, IL-4, IL-6, IL-10, IL-17 and tumor necrosis factor (TNF) α), α- and β-chemokines, including IL-8 and IL-16, as well as adipokines (leptin and adiponectin) in the peripheral blood of patients with type 2 diabetes (T2D) with normal and increased body weight/obesity. It has been shown that patients with T2D are characterized by an increased content of proinflammatory cytokines (IL-1, IL-6, IL-17, TNFα), α- and β-chemokines in the peripheral blood, including IL-8 and IL-16, as well as leptin with a decrease in adiponectin content. In lean patients (with body mass index (BMI)<25.5 kg/m2) compared to lean normoglycemic individuals from the control group (BMI<25.5kg/m2), there is a small but significant increase in IL-1β, IL-6, IL-17, TNFα and leptin, which, as BMI increases, significantly increases in severe obesity (BMI>30.0kg/m2), especially in obese women (BMI>35.0kg/m2). Similarly, an increase in proinflammatory cytokines is observed in normoglycemic people, but not as significant as in T2D. Less clear data were obtained when during determination of the anti-inflammatory cytokines IL-4 and IL-10, which is explained by a significant polymorphism of their genes, and both protective and compensatory effects on pro-inflammatory cytokine rise. In T2D patients, especially those with obesity, there is an increase in the leptin level and a decrease in the adiponectin content. The severity of the course and the percentage of mortality are closely associated with the BMI of patients. The effectiveness of the fight against an increase in the incidence of T2D should be primarily aimed at preventing obesity, and in case of already developed T2D— at reducing concomitant obesity. The analysis of the data presented also suggests that a sharp increase in the content of pro-inflammatory cytokines (so called cytokine storm) observed in patients with T2D and obesity infected with COVID-19, is a consequence of the summation and potentiation of already existing inflammatory process.

Gut microbiota and its metabolites: Bridge of dietary nutrients and obesity-related diseases

While the incidence of obesity keeps increasing in both adults and children worldwide, obesity and its complications remain major threatens to human health. Over the past decades, accumulating evidence has demonstrated the importance of microorganisms and their metabolites in the pathogenesis of obesity and related diseases. There also is a significant body of evidence validating the efficacy of microbial based therapies for managing various diseases. In this review, we collected the key information pertinent to obesity-related bacteria, fermentation substrates and major metabolites generated by studies involving humans and/or mice. We then briefly described the possible molecular mechanisms by which microorganisms cause or inhibit obesity with a focus on microbial metabolites. Lastly, we summarized the advantages and disadvantages of the utilization of probiotics, plant extracts, and exercise in controlling obesity. We speculated that new targets and combined approaches (e.g. diet combined with exercise) could lead to more precise prevention and/or alleviation of obesity in future clinical research implications.

Zinc and the Innovative Zinc-α2-Glycoprotein Adipokine Play an Important Role in Lipid Metabolism: A Critical Review

Numerous studies indicate that zinc and the new zinc-related adipokine, zinc-α2-glycoprotein (ZAG), are involved in lipid metabolism. Excess body fat lowers blood concentrations of Zn and ZAG, leading not only to the development of obesity but also to other components of the metabolic syndrome. Zinc homeostasis disorders in the body negatively affect the lipid profile and cytokine secretion. Zinc appears to be a very important ZAG homeostasis regulator. The physiological effects of ZAG are related to lipid metabolism, but studies show that ZAG also affects glucose metabolism and is linked to insulin resistance. ZAG has a zinc binding site in its structure, which may indicate that ZAG mediates the effect of zinc on lipid metabolism. The review aimed to verify the available studies on the effects of zinc and ZAG on lipid metabolism. A literature review within the scope of this research area was conducted using articles available in PubMed (including MEDLINE), Web of Science and Cochrane Library databases. An analysis of available studies has shown that zinc improves hepatic lipid metabolism and has an impact on the lipid profile. Numerous studies have found that zinc supplementation in overweight individuals significantly reduced blood levels of total cholesterol, LDL (Low-density lipoprotein)cholesterol and triglycerides, potentially reducing cardiovascular morbidity and mortality. Some results also indicate that it increases HDL-C (High-density lipoprotein) cholesterol levels. ZAG has been shown to play a significant role in reducing obesity and improving insulin sensitivity, both in experimental animal model studies and in human studies. Furthermore, ZAG at physiologically relevant concentrations increases the release of adiponectin from human adipocytes. In addition, ZAG has been shown to inhibit in vitro leptin production. Further studies are needed to provide more data on the role of zinc and zinc-α2-glycoprotein.

Effects of Ramadan intermittent fasting on leptin and adiponectin: a systematic review and meta-analysis

OBJECTIVES

Ramadan intermittent fasting may affect whole-body metabolism by affecting appetite-related hormones. This systematic review and meta-analysis aimed to clarify the possible effects of Ramadan intermittent fasting on the main hormones regulating appetite and satiety, including leptin and adiponectin.

METHODS

All English language papers in the PubMed, Scopus, and Embase databases were searched using the keywords "Ramadan fasting", "adiponectin", and "leptin", up to 2020. Data extraction was conducted based on the main data of the studies; the primary outcomes of the analysis were mean changes of adiponectin and leptin levels during the holy month of Ramadan in fasted subjects.

MAIN RESULTS

Data of 16 eligible studies, conducted between 2003 and 2020, were included in the systematic review. Of these, 10 studies with complete data on leptin and adiponectin were included in the meta-analysis. A significant decrease in leptin levels was observed after Ramadan fasting (WMD = -2.28 ng/ml, 95% CI = -3.72, -0.84). Ramadan fasting had no significant effect on adiponectin levels (WMD = 2.19 ng/ml, 95% CI = -0.29, 4.67). Sub-group analysis demonstrated a greater decrease in leptin levels among normal-weight subjects compared to those of overweight/obese subjects (WMD = -4.67 ng/ml, 95% CI = -6.03, -3.31 vs. WMD = -3.43 ng/ml, 95% CI = -5.69, -1.17).

CONCLUSION

Ramadan fasting may decrease leptin levels, especially in normal-weight subjects. There was high heterogeneity, which may be explained by the differences between the wide ranges of study conditions.

Leptin and Obesity: Role and Clinical Implication

The peptide hormone leptin regulates food intake, body mass, and reproductive function and plays a role in fetal growth, proinflammatory immune responses, angiogenesis and lipolysis. Leptin is a product of the obese (ob) gene and, following synthesis and secretion from fat cells in white adipose tissue, binds to and activates its cognate receptor, the leptin receptor (LEP-R). LEP-R distribution facilitates leptin's pleiotropic effects, playing a crucial role in regulating body mass via a negative feedback mechanism between adipose tissue and the hypothalamus. Leptin resistance is characterized by reduced satiety, over-consumption of nutrients, and increased total body mass. Often this leads to obesity, which reduces the effectiveness of using exogenous leptin as a therapeutic agent. Thus, combining leptin therapies with leptin sensitizers may help overcome such resistance and, consequently, obesity. This review examines recent data obtained from human and animal studies related to leptin, its role in obesity, and its usefulness in obesity treatment.

Preterm human milk: associations between perinatal factors and hormone concentrations throughout lactation

BACKGROUND

Infants born moderate to late preterm constitute the majority of preterm births, yet guidelines for their nutritional care are unclear. Maternal milk is the most appropriate nutrition for these infants; however, its composition can be influenced by environmental factors. The present study therefore investigated perinatal predictors of human milk composition in a preterm cohort.

METHODS

Milk was collected during the DIAMOND trial (DIfferent Approaches to Moderate and late preterm Nutrition: Determinants of feed tolerance, body composition and development) from 169 mothers of 191 infants at three time-points (5 and 10 days post partum and 4 months' corrected age). Leptin, adiponectin and insulin-like growth factor-1 (IGF-1) were analysed by enzyme-linked immunosorbent assay. Generalised mixed models were used to evaluate associations between milk composition and maternal/infant/perinatal factors.

RESULTS

Most findings were independent of collection time-point. Gestational diabetes was associated with lower adiponectin. Higher adiponectin and lower leptin were associated with higher socioeconomic status, higher maternal education and ability to fully breastfeed at discharge from hospital. Higher leptin was associated with high perceived stress during hospital admission. Milk IGF-1 displayed sex-specific patterns in association with maternal social deprivation.

CONCLUSION

Maternal, infant and environmental factors during the perinatal period were associated with milk compositional profiles throughout lactation. Further clinical trials should investigate the impact of such changes in terms of long-term infant outcomes.

IMPACT

Human milk is the best nutrition for the infant. However, its composition may be susceptible to alterations determined by pathological conditions mother and infant may face throughout pregnancy and in the perinatal period. This study found that perinatal factors are associated with human milk composition from early to late lactation. If human milk composition throughout lactation is "programmed" during pregnancy or early lactation, infants who were exposed in utero to environmental insults may still be exposed to them during lactation. The impact of human milk compositional alteration on infant growth following perinatal pathological events requires further investigation.

Genetics of mouse behavioral and peripheral neural responses to sucrose

Mice of the C57BL/6ByJ (B6) strain have higher consumption of sucrose, and stronger peripheral neural responses to it, than do mice of the 129P3/J (129) strain. To identify quantitative trait loci (QTLs) responsible for this strain difference and to evaluate the contribution of peripheral taste responsiveness to individual differences in sucrose intake, we produced an intercross (F₂) of 627 mice, measured their sucrose consumption in two-bottle choice tests, recorded the electrophysiological activity of the chorda tympani nerve elicited by sucrose in a subset of F₂ mice, and genotyped the mice with DNA markers distributed in every mouse chromosome. We confirmed a sucrose consumption QTL (Scon2, or Sac) on mouse chromosome (Chr) 4, harboring the Tas1r3 gene, which encodes the sweet taste receptor subunit TAS1R3 and affects both behavioral and neural responses to sucrose. For sucrose consumption, we also detected five new main-effect QTLs, Scon6 (Chr2), Scon7 (Chr5), Scon8 (Chr8), Scon3 (Chr9), and Scon9 (Chr15), and an epistatically interacting QTL pair Scon4 (Chr1) and Scon3 (Chr9). No additional QTLs for the taste nerve responses to sucrose were detected besides Scon2 (Tas1r3) on Chr4. Identification of the causal genes and variants for these sucrose consumption QTLs may point to novel mechanisms beyond peripheral taste sensitivity that could be harnessed to control obesity and diabetes.

Undernutrition induces major alterations in the lipid droplets of white and brown adipose tissues in wistar rats

Several studies have shown a relationship between the distribution of fat mass around the organism, metabolic disorders, and an increased risk of morbidity and mortality. It has been demonstrated that in obese animals there is a big rise in the white fat deposits due to hyperplasia and hypertrophy of the adipocytes. Studies related to weight and health have been more popular regarding obesity rather than extreme caquexia or calorico-proteic deficiencies, but these states are interesting from the point of view of the preferential atrophy of certain organs that may help us in the understanding of undernourishment. Moreover, the discovery of beige adipose tissue has instigated thoughts around the roles played by the different cells in the adipose tissue as well as its adaptability in pathological states. In our study we carried out morphometric, morphological, and quantitative measurements of the adipose tissue in an animal model based on a 40-50% diet restriction in comparison to control animals. We have found a decrease in the size of white adipocytes together with a variation in the lipid droplet size of brown adipocytes in undernourished animals, what may be considered as possible transformations between the types of adipose tissues, and that could be caused by an adaptive phenomenon to the undernourished state.

Harmful effects of high amounts of glucose on the immune system: An updated review

Release and storage of energy can be regulated by the metabolic parameter dependent on the central nervous system. Macrophages are one of the most professional antigen-presenting cells that are formed by the accumulation of dead or damaged cells or in response to the infection, which has the main function of phagocytosis, secretion of cytokines, and presenting antigen to T cells. A proper immune response is needed for the production of effector cytokines along with comprehensive and rapid cell proliferation and growth. Activation of the immune system and immune cells is needed to increase glucose metabolism. When the immune system responds to pathogens, chemokines inform immune cells such as macrophages and T cells to travel to the infected area. Although glucose is vital for the proper function of immune cells and their proliferation, a high amount of glucose may lead to impaired function of the immune system and pathological conditions. However, a suitable amount of glucose is indispensable for the immune system, but its elevated amount leads to excessive proinflammatory cytokines production. In this study, we focused on the master regulatory role of glucose on the immune system.

Antrodia cinnamomea Confers Obesity Resistance and Restores Intestinal Barrier Integrity in Leptin-deficient Obese Mice

Obesity is associated with metabolic disorders. Thus, obesity prevention and treatment are essential for health. Antrodia cinnamomea (AC) is a multifunctional medicinal fungus used for the treatment of various diseases and for preventing diet-induced obesity. Leptin deficiency causes over-eating and spontaneous obesity. The concomitant metabolic symptoms are more severe than diet-induced obesity. Here, we used leptin-deficient (ob/ob) mice as an animal model for over-feeding to study the effect of AC on obesity. We fed C57BL/6 mice (WT, ob+/+) and ob/ob mice with AC for four weeks before performing qRT-PCR and immunoblot analysis to elaborate AC-modulated mechanisms. Further, we used Caco-2 cells as a human intestinal epithelial barrier model to examine the effect of AC on intestinal permeability. Our results suggested that AC reduces lipid deposits of the liver and epididymal white adipose tissue (EWAT) by promoting lipid metabolism and inhibiting lipogenesis-associated genes and proteins in ob/ob mice. Moreover, AC effectively repaired intestinal-barrier injury caused by leptin deficiency and enhanced intestinal barrier integrity in Caco-2 cells. Interestingly, AC significantly reduced body weight and EWAT with no compromise on food intake in ob/ob mice. Thus, AC effectively reduced obesity caused by leptin-deficiency and can potentially be used as a nutraceutical for treating obesity.

Leptin enhances N-methyl-N'-nitro-N-nitrosoguanidine (MNNG)-induced tumour growth in gastric mucosa of male Sprague-Dawley rats

Individuals who are obese are at a greater risk of developing gastric cancer. They are however also hyperleptinaemic. Chronic leptin treatment has been shown to upregulate numerous cancer-causing genes in the stomach of male Sprague-Dawley rats. It is however unclear if leptin enhances the effect of gastric carcinogens in vivo. This study was therefore done to investigate the effect of leptin on gastric carcinogenesis in rats treated with N-methyl-N'-nitro-N-nitrosoguanidine (MNNG). Twenty-four, 6-week old male Sprague-Dawley rats were divided equally into three groups: G1 served as age-matched controls; G2 was treated with MNNG in drinking water ad libitum (200 mg L^-1); G3 was given leptin and MNNG. Rats were euthanized after 40 weeks of treatment and their stomachs were removed for histopathology, microarray, and RT-qPCR analysis. Fisher's exact test and one-way ANOVA were used to analyse the data. Fifty percent of the MNNG-treated rats developed gastric hyperplasia (p < 0.05), but there was no significant change in any carcinogenic genes. Concurrent MNNG and leptin treatment however induced hyperplasia, dysplasia, hypertrophy, and adenocarcinoma in 75% (6/8) of the rats; with upregulation of microRNAs, olfactory receptors, Hey2 (transcription factor), Tmed2 (vesicular trafficking), and Lcn11 (cell proliferation) genes. It appears that leptin enhances MNNG- induced tumour growth in stomachs of Sprague-Dawley rats and its role in gastric cancer requires further scrutiny.

High potency multistrain probiotic improves liver histology in non-alcoholic fatty liver disease (NAFLD): a randomised, double-blind, proof of concept study

Objective

Pharmacological treatment of non-alcoholic fatty liver disease (NAFLD) is still evolving. Probiotics could be a promising treatment option, but their effectiveness needs to be established. The present study aimed to evaluate the efficacy of a high potency multistrain probiotic in adult patients with NAFLD.

Methods

Thirty-nine liver biopsy-proven patients with NAFLD were randomised in a double-blind fashion to either lifestyle modifications plus an oral multistrain probiotic (675 billion bacteria daily, n=19) or identical placebo (n=20) for 1 year. Lifestyle modifications included regular exercise for all and control of overweight/obesity (with additional dietary restrictions), hypertension and hyperlipidaemia in those with these risk factors. Primary objective of the study was the histological improvement in NAFLD activity score (NAS) and its components and secondary objectives were improvement in alanine transaminase (ALT) and cytokine profile.

Results

Thirty (76.9%) out of 39 patients with NAFLD completed the study with 1 year of follow-up. A repeat liver biopsy at 1 year could be done in 10 patients (52.6%) in probiotic group and five patients (25%) in placebo group. In comparison to baseline, hepatocyte ballooning (p=0.036), lobular inflammation (p=0.003) and NAS score (p=0.007) improved significantly at 1 year in the probiotic group. When compared with placebo, the NAS score improved significantly in the probiotic group (p=0.004), along with improvements in hepatocyte ballooning (p=0.05) and hepatic fibrosis (p=0.018). A significant improvement in levels of ALT (p=0.046), leptin (p=0.006), tumour necrosis factor-α (p=0.016) and endotoxins (p=0.017) was observed in probiotic group in comparison to placebo at 1 year. No significant adverse events were reported in the study.

Conclusion

Patients with NAFLD managed with lifestyle modifications and multistrain probiotic showed significant improvement in liver histology, ALT and cytokines.

Trial registration number

The clinical trial is registered with CLINICAL TRIAL REGISTRYINDIA (CTRI); http://ctri.nic.in, No. CTRI/2008/091/000074

Estrogen-independent role of ERα in ovarian cancer progression induced by leptin/Ob-Rb axis

Leptin induces ovarian cancer cell invasion via overexpression of MMP7, MMP9, and upA. In addition, the key role of ERα in leptin-increased cell growth was indicated. However, the influence of ER on leptin-mediated cell invasion remains still unknown. The present study was designed to evaluate the E2-independent effect of ERα/β on leptin-mediated cell invasion and cell proliferation in ovarian cancer. We utilized SKOV3 cancer (expressing OB-Rb and ERα/β, insensitive to estrogen) and OVCAR3 (expressing OB-Rb) cell lines to show the involvement of ER in leptin-mediated effects in an E2-independent manner. MTT, BrdU, and BD matrigel invasion assays were applied to analyze cell growth, proliferation, and invasion. The siRNA approach was used to confirm the role of ERα/β in leptin effects. Moreover, western blotting and Real-time PCR were employed to detect the OB-Rb, ER, MMP9/7, and upA proteins and mRNAs. Leptin, in the absence of E2, increased ERα expression in SKOV3 cells, which was attenuated using knockdown of OB-Rb gene by siRNA. The effect of leptin on the cell growth was promoted in the presence of PPT, but not in the presence of DNP and E2, which was lost when OB-Rb siRNA was transfected. Furthermore, ERα gene silencing and/or pre-incubation with ER antagonist (ICI 182,780, 10 nM) significantly reduced cell invasion and MMP9 expression stimulated by leptin. In conclusion, our findings demonstrated that ERα, but not ERβ, is involved in leptin-induced ovarian cancer in an E2-independent manner, providing new evidence for cancer progression in obesity-associated ovarian cancer.

Role of eating disorders-related polymorphisms in obesity pathophysiology

Human biological system provides innumerable neuroendocrine inputs for food intake control, with effects on appetite's modulation and the satiety signs. Its regulation is very complex, engaging several molecular interactions with many tissues, hormones, and neural circuits. Thus, signaling molecules that control food intake are critical for normal energy homeostasis and a deregulation of these pathways can lead to eating disorders and obesity. In line of this, genetic factors have a significantly influence of the regulation of neural circuits controlling the appetite and satiety pathways, as well as the regulation of brain reward systems. Single Nucleotide Polymorphisms (SNPs) in genes related to hypothalamic appetite and satiety mechanisms, further in multiple neurotransmitter systems may contribute to the development of major Eating Disorders (EDs) related to obesity, among them Binge Eating Disorder (BED) and Bulimia Nervosa (BN), which are discussed in this review.

Antipsychotics-induced metabolic alterations: Recounting the mechanistic insights, therapeutic targets and pharmacological alternatives

Atypical antipsychotics (AAPs) are the drug of choice in the management of mental illnesses by virtue of their advantage over typical antipsychotics i.e. least tendency of producing extrapyramidal motor symptoms (EPS) or pseudoparkinsonism. Despite the clinical efficacy, AAPs produces troublesome adverse effects, particularly hyperphagia, hyperglycemia, dyslipidemia weight gain, diabetes mellitus, insulin resistance and QT prolongation which further develops metabolic and cardiac complications with subsequent reduction in life expectancy, poor patient compliance, and sudden death. AAPs-induced weight gain and metabolic alterations are increasing at an alarming rate and became an utmost matter of concern for psychopharmacotherapy. Diverse underlying mechanisms have been explored such as the interaction of AAPs with neurotransmitter receptors, alteration in food reward anticipation behavior, altered expressions of hypothalamic orexigenic and anorexigenic neuropeptides, histamine H₁ receptor-mediated hypothalamic AMP-activated protein kinase (AMPK) activation, increased blood leptin, ghrelin, pro-inflammatory cytokines. Antipsychotics induced imbalance in energy homeostasis, reduction in energy expenditure which is linked to altered expression of uncoupling proteins (UCP-1) in brown adipose tissue and reduced hypothalamic orexin expressions are emerging insights. In addition, alteration in gut-microbiota and subsequent inflammation, dyslipidemia, obesity, and diabetes after AAPs treatment are also associated with weight gain and metabolic alterations. Oral hypoglycemics and lipid-lowering drugs are mainly prescribed in the clinical management of weight gain associated with AAPs while many other pharmacological and nonpharmacological interventions also have been explored in different clinical and preclinical studies. In this review, we critically discuss the current scenario, mechanistic insights, biomarkers, and therapeutic alternatives for metabolic alterations associated with antipsychotics.

Transcriptome analysis of adipose tissue from pigs divergent in feed efficiency reveals alteration in gene networks related to adipose growth, lipid metabolism, extracellular matrix, and immune response

Adipose tissue is hypothesized to play a vital role in regulation of feed efficiency (FE; efficiency in converting energy and nutrients into tissue), of which improvement will simultaneously reduce environmental impact and feed cost per pig. The objective of the present study was to sequence the subcutaneous adipose tissue transcriptome in FE-divergent pigs (n = 16) and identify relevant biological processes underpinning observed differences in FE. We previously demonstrated that high-FE pigs were associated with lower fatness when compared to their counterparts. Here, ontology analysis of a total of 209 annotated genes that were differentially expressed at a p < 0.01 revealed establishment of a dense extracellular matrix and inhibition of capillary formation as one underlying mechanism to achieve suppressed adipogenesis. Moreover, mechanisms ensuring an efficient utilization of lipids in high-FE pigs might be orchestrated by upstream regulators including CEBPA and EGF. Consequently, high-FE adipose tissue could exhibit more efficient cholesterol disposal, whilst inhibition of inflammatory and immune response in high-FE pigs may be an indicator of an optimally functioning adipose tissue. Taken together, adipose tissue growth, extracellular matrix formation, lipid metabolism and inflammatory and immune response are key biological events underpinning the differences in FE. Further investigations focusing on elucidating these processes would assist the animal production industry in optimizing strategies related to nutrient utilization and product quality.

Leptin induces the expression of tumorigenic genes in the gastric mucosa of male Sprague-Dawley rats

Leptin promotes the growth of gastric cancer cells in vitro. It is, however, unknown if leptin induces gastric cancer in vivo. This study therefore investigated the effect of leptin on the histology and expression of tumorigenic genes in the stomach of rats following 40 weeks of leptin treatment. Male Sprague-Dawley rats, aged 6 weeks, were randomized into control and experimental groups ( n = 8 per group). The experimental group was given intraperitoneal injections of leptin (60 µg/kg/day) once daily for 40 weeks, whereas the control group received intraperitoneal injection of an equal volume of normal saline daily. Rats were housed in polypropylene cages for the duration of the study. Body weight was measured weekly. Upon completion of treatment, rats were euthanized and their stomachs were collected for histopathological examination, microarray, and RT-qPCR. Data were analyzed using one-way ANOVA and Fisher’s exact test. On histology, one rat (12.5%) in the leptin-treated group had a large red-colored tumor nodule at the pyloric antrum of the stomach. Microscopically, stomachs of two leptin-treated rats (25%) showed hyperplasia or dysplasia. Microarray analysis revealed significant upregulation of a number of genes in the stomachs of leptin-treated rats that have been shown to be associated with tumorigenesis in other tissues, including Furin (protein maturation), Eef1a1 and Eif4g2 (translation factors), Tmed2 (vesicular trafficking), Rab7a (plasma membrane trafficking), Rfwd2 (protein degradation), Fth1 and Ftl1 (oxygen transport), Tspan8, Tspan1, Fxyd3, and Rack1 (cell migration), Pde4d (signal transduction), Nupr1 and Ybx1 (transcription factors), Ptma and Tmem134 (oncogenes), Srsf2 (mRNA maturation), and Reep5 (cell proliferation). None of the known oncogenes were, however, significantly up-regulated. In conclusion, although the overall effect of leptin on gastric carcinogenesis seems inconclusive, the findings of dysplasia and the up-regulation of some of the cancer-related genes nevertheless warrant further scrutiny on the role of leptin in gastric cancer.

Impact statement

Gastric cancer is the third most common cause of death due to cancer in the world. Obese individuals are at risk of developing gastric cancer, and the reason for this is unknown. Serum leptin levels are high in obese individuals and leptin is known to induce proliferation of gastric cancer cells in vitro. However, to date, no reports exist on the tumorigenic effects of leptin on the stomach in vivo. This study therefore determines if chronic leptin administration induces gastric carcinogenesis in non-obese rats, which might serve as a useful animal model for future studies. Although the findings are somewhat inconclusive, to our knowledge, however, this is the first study to show the up-regulation of numerous potential driver genes that highlight the potential role of leptin in the higher prevalence of gastric cancer among obese individuals. The findings certainly necessitate further scrutiny of leptin gastric cancer.

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.

Endocannabinoid-dependent disinhibition of orexinergic neurons: Electrophysiological evidence in leptin-knockout obese mice

OBJECTIVES

In the ob/ob mouse model of obesity, chronic absence of leptin causes a significant increase of orexin (OX) production by hypothalamic neurons and excessive food intake. The altered OX level is linked to a dramatic increase of the inhibitory innervation of OX producing neurons (OX neurons) and the over expression of the endocannabinoid 2-arachidonoylglycerol (2-AG) by OX neurons of ob/ob mice. Little is known about the function of the excitatory synapses of OX neurons in ob/ob mice, and their modulation by 2-AG. In the present study, we fill this gap and provide the first evidence of the overall level of activation of OX neurons in the ob/ob mice.

METHODS

We performed in vitro whole-cell patch-clamp recordings on OX neurons located in the perifornical area of the lateral hypothalamus in acute brain slices of wt and ob/ob mice. We identified OX neurons on the basis of their electrophysiological membrane properties, with 96% of concordance with immunohistochemisty.

RESULTS

We found that OX neurons of ob/ob mice are innervated by less efficient and fewer excitatory synapses than wt mice. Consequently, ob/ob OX neurons show more negative resting membrane potential and lower action potential firing frequency than wt. The bath application of the cannabinoid type-1 receptor agonist WIN55,212-2, depresses both the excitatory and the inhibitory synapses in ob/ob animals, but only the excitatory synapses in wt animals. Finally, the physiologic release of 2-AG induces a prevalent depression of inhibition (disinhibition) of OX neurons in ob/ob animals but not in wt.

CONCLUSIONS

In ob/ob mice, chronic absence of leptin induces a 2-AG mediated functional disinhibition of OX neurons. This helps explain the increase of OX production and, consequently, the excessive food intake of ob/ob mice.

Association between obesity and asthma - epidemiology, pathophysiology and clinical profile

Obesity is a risk factor for asthma, and obese asthmatics have lower disease control and increased symptom severity. Several putative links have been proposed, including genetics, mechanical restriction of the chest and the intake of corticosteroids. The most consistent evidence, however, comes from studies of cytokines produced by the adipose tissue called adipokines. Adipokine imbalance is associated with both proinflammatory status and asthma. Although reverse causation has been proposed, it is now acknowledged that obesity precedes asthma symptoms. Nevertheless, prenatal origins of both conditions complicate the search for causality. There is a confirmed role of neuro-immune cross-talk mediating obesity-induced asthma, with leptin playing a key role in these processes. Obesity-induced asthma is now considered a distinct asthma phenotype. In fact, it is one of the most important determinants of asthma phenotypes. Two main subphenotypes have been distinguished. The first phenotype, which affects adult women, is characterised by later onset and is more likely to be non-atopic. The childhood obesity-induced asthma phenotype is characterised by primary and predominantly atopic asthma. In obesity-induced asthma, the immune responses are shifted towards T helper (Th) 1 polarisation rather than the typical atopic Th2 immunological profile. Moreover, obese asthmatics might respond differently to environmental triggers. The high cost of treatment of obesity-related asthma, and the burden it causes for the patients and their families call for urgent intervention. Phenotype-specific approaches seem to be crucial for the success of prevention and treatment.

Cancer as a Proinflammatory Environment: Metastasis and Cachexia

The development of the syndrome of cancer cachexia and that of metastasis are related with a poor prognostic for cancer patients. They are considered multifactorial processes associated with a proinflammatory environment, to which tumour microenvironment and other tissues from the tumour bearing individuals contribute. The aim of the present review is to address the role of ghrelin, myostatin, leptin, HIF, IL-6, TNF-α, and ANGPTL-4 in the regulation of energy balance, tumour development, and tumoural cell invasion. Hypoxia induced factor plays a prominent role in tumour macro- and microenvironment, by modulating the release of proinflammatory cytokines.

Sick of sitting

Sitting too much kills. Epidemiological, physiological and molecular data suggest that sedentary lifestyle can explain, in part, how modernity is associated with obesity, more than 30 chronic diseases and conditions and high healthcare costs. Excessive sitting--sitting disease--is not innate to the human condition. People were designed to be bipedal and, before the industrial revolution, people moved substantially more throughout the day than they do presently. It is encouraging that solutions exist to reverse sitting disease. Work environments, schools, communities and cities can be re-imagined and re-invented as walking spaces, and people thereby offered more active, happier, healthier and more productive lives.

Rationale and design of REWARD (revving-up exercise for sustained weight loss by altering neurological reward and drive): a randomized trial in obese endometrial cancer survivors

BACKGROUND

Obesity is a leading risk factor for endometrial cancer (EC), particularly Type I forms, which are increasing in the U.S. Although death rates from most cancers have been decreasing, overall mortality in EC is increasing in the U.S. EC survivors' poor fitness combined with their surgical treatments may make weight loss particularly challenging. High intensity exercise increases neurotrophins and neurological reward via altered striatal dopamine in animals, and, in humans, chronic high intensity exercise enhances meal-induced satiety and may reduce hedonic eating. "Assisted" exercise, a mode of exercise whereby a patient's voluntary exercise rate is augmented mechanically, may modulate brain dopamine levels in Parkinson's Disease patients but has not been previously evaluated as a treatment for obesity.

METHODS

We describe the rationale and design of the REWARD trial, which has the overarching goal of randomizing 120 obese EC survivors to "assisted" or voluntary rate cycling to evaluate the efficacy of "assisted" exercise in enhancing and sustaining weight loss. Patients in both arms will receive 3 days/week of supervised exercise and 1 day/week of a group dietary behavioral intervention for 16 weeks and, then, will be followed for 6 months.

OUTCOMES

The primary outcome is weight loss. Secondary outcomes include measures for body composition, fitness, eating behavior, exercise motivation and, quality of life as well as cognition and food reward and motivation as assessed by functional magnetic resonance imaging (fMRI) tasks.

CONCLUSIONS

If successful, the REWARD program could be extended to help sustain weight loss in obese cancer and non-cancer patients.

Carotid chemoreceptor afferent projections to leptin receptor containing neurons in nucleus of the solitary tract

Neurons expressing the leptin receptor (Ob-R) exist within the caudal nucleus of the solitary tract (NTS). Additionally, afferent neurons expressing the Ob-R have been identified within the nodose ganglion and NTS. Furthermore, systemic injections or focal injections of leptin directly into NTS potentiate the response of NTS neurons to carotid chemoreceptor activation. However, the distribution of carotid body afferents in relation to Ob-R containing neurons within NTS is not known. In this study, chemoreceptor afferent fibers were labeled following microinjection of the anterograde tract tracer biotinylated dextran amine (BDA) into the carotid body or petrosal/nodose ganglion of Wistar rats. After a survival period of 10-14 days, the NTS was processed for BDA and Ob-R immunoreactivity. Afferent axons originating in the carotid body were found to project to the lateral (Slt), gelantinosa (Sg), and medial (Sm) subnuclei of the NTS complex. A similar, but more robust distribution of BDA labeled fibers was observed in the NTS complex after injections into the petrosal/nodose ganglion. Carotid body BDA labeled fibers were observed in close apposition to Ob-R immunoreactive neurons in the region of Slt, Sg and Sm. In addition, a small number of carotid body afferents were found to contain both BDA and express Ob-R-like immunoreactivity within the regions of Slt, Sg and Sm. Taken together, these data suggest that leptin may modulate carotid chemoreceptor function not only through direct effects on NTS neurons, but also through a direct effect on carotid body primary afferent fibers that innervate NTS neurons.

Overnutrition stimulates intestinal epithelium proliferation through β-catenin signaling in obese mice

Obesity is a major risk factor for type 2 diabetes and cardiovascular diseases. And overnutrition is a leading cause of obesity. After most nutrients are ingested, they are absorbed in the small intestine. Signals from β-catenin are essential to maintain development of the small intestine and homeostasis. In this study, we used a hyperphagia db/db obese mouse model and a high-fat diet (HFD)-induced obesity mouse model to investigate the effects of overnutrition on intestinal function and β-catenin signaling. The β-catenin protein was upregulated along with inactivation of glycogen synthase kinase (GSK)-3β in the intestines of both db/db and HFD mice. Proliferation of intestinal epithelial stem cells, villi length, nutrient absorption, and body weight also increased in both models. These changes were reversed by caloric restriction in db/db mice and by β-catenin inhibitor JW55 (a small molecule that increases β-catenin degradation) in HFD mice. Parallel, in vitro experiments showed that β-catenin accumulation and cell proliferation stimulated by glucose were blocked by the β-catenin inhibitor FH535. And the GSK-3 inhibitor CHIR98014 in an intestinal epithelial cell line increased β-catenin accumulation and cyclin D1 expression. These results suggested that, besides contribution to intestinal development and homeostasis, GSK-3β/β-catenin signaling plays a central role in intestinal morphological and functional changes in response to overnutrition. Manipulating the GSK-3β/β-catenin signaling pathway in intestinal epithelium might become a therapeutic intervention for obesity induced by overnutrition.

Plasma leptin inhibits the response of nucleus of the solitary tract neurons to aortic baroreceptor stimulation

Leptin receptors have been identified within the nucleus of the solitary tract (NTS) and leptin injections into the caudal NTS inhibit the baroreceptor reflex. However, whether plasma leptin alters the discharge of NTS neurons mediating aortic baroreceptor reflex activity is not known. A series of electrophysiological single unit recording experiments was done in the urethane-chloralose anesthetized, paralyzed and artificially ventilated Wistar and Zucker obese rat with either their neuroaxis intact or with mid-collicular transections. Single units in NTS antidromically activated by electrical stimulation of depressor sites in the caudal ventrolateral medulla (CVLM) were found to display a cardiac cycle-related rhythmicity. These units were tested for their responses to stimulation of the aortic depressor nerve (ADN) and intra-carotid injections of leptin (50-200ng/0.1ml). Of 63 single units tested in NTS, 33 were antidromically activated by stimulation of CVLM depressor sites and 18 of these single units responded with a decrease in discharge rate after intracarotid injections of leptin. Thirteen of these leptin responsive neurons (∼72%) were excited by ADN stimulation. Furthermore, the excitatory response of these single units to ADN stimulation was attenuated by about 50% after the intracarotid leptin injection. Intracarotid injections of leptin (200ng/0.1ml) in the Zucker obese rat did not alter the discharge rate of NTS-CVLM projecting neurons. These data suggest that leptin exerts a modulatory effect on brainstem neuronal circuits that control cardiovascular responses elicited during the reflex activation of arterial baroreceptors.

Limits to sustained energy intake. XVII. Lactation performance in MF1 mice is not programmed by fetal number during pregnancy

Several studies have suggested that lactation performance may be programmed by the number of fetuses during pregnancy, whereas other studies indicate that processes during lactation are more important. As gestation litter size and litter size in lactation are usually strongly correlated, separating the roles of pregnancy and lactation in lactation performance is difficult. To break this link, we experimentally manipulated litter size of MF1 mice to five or 16 pups per litter by cross-fostering. Litter size and mass at birth were recorded on day 1 of lactation prior to litter size manipulation. Maternal body mass and food intake, litter size and litter mass were measured daily throughout. After weaning, the potential differential utilisation of body tissues of the mothers was investigated. Relationships between maternal mass and food intake, including asymptotic daily food intake at peak lactation, offspring traits and other maternal parameters suggested that the number of fetuses the females had carried during pregnancy had no effect on lactation performance. Litter mass increases depended only on maternal food intake, which was highly variable between individuals, but was independent of fetal litter size. The sizes of key organs and tissues like the liver and alimentary tract were not related to maximal food intake at peak lactation or to fetal litter size, but the masses of the pelage, mammary glands and retroperitoneal fat pad were. These data suggest that while growth of the mammary glands and associated structures may be initiated in gestation, and vary in relation to the number of placentas, the ultimate sizes and activities of the tissues depends primarily on factors during lactation.

Leptin in nucleus of the solitary tract alters the cardiovascular responses to aortic baroreceptor activation

Recent data suggests that neurons expressing the long form of the leptin receptor form at least two distinct groups within the caudal nucleus of the solitary tract (NTS): a group within the lateral NTS (Slt) and one within the medial (Sm) and gelantinosa (Sg) NTS. Discrete injections of leptin into Sm and Sg, a region that receives chemoreceptor input, elicit increases in arterial pressure (AP) and renal sympathetic nerve activity (RSNA). However, the effect of microinjections of leptin into Slt, a region that receives baroreceptor input is unknown. Experiments were done in the urethane-chloralose anesthetized, paralyzed and artificially ventilated Wistar or Zucker obese rat to determine leptin's effect in Slt on heart rate (HR), AP and RSNA during electrical stimulation of the aortic depressor nerve (ADN). Depressor sites within Slt were first identified by the microinjection of l-glutamate (Glu; 0.25M; 10nl) followed by leptin microinjections. In the Wistar rat leptin microinjection (50ng; 20nl) into depressor sites within the lateral Slt elicited increases in HR and RSNA, but no changes in AP. Additionally, leptin injections into Slt prior to Glu injections at the same site or to stimulation of the ADN were found to attenuate the decreases in HR, AP and RSNA to both the Glu injection and ADN stimulation. In Zucker obese rats, leptin injections into NTS depressor sites did not elicit cardiovascular responses, nor altered the cardiovascular responses elicited by stimulation of ADN. Those data suggest that leptin acts at the level of NTS to alter the activity of neurons that mediate the cardiovascular responses to activation of the aortic baroreceptor reflex.

A C. elegans model to study human metabolic regulation

Lipid metabolic disorder is a critical risk factor for metabolic syndrome, triggering debilitating diseases like obesity and diabetes. Both obesity and diabetes are the epicenter of important medical issues, representing a major international public health threat. Accumulation of fat in adipose tissue, muscles and liver and/or the defects in their ability to metabolize fatty acids, results in insulin resistance. This triggers an early pathogenesis of type 2 diabetes (T2D). In mammals, lipid metabolism involves several organs, including the brain, adipose tissue, muscles, liver, and gut. These organs are part of complex homeostatic system and communicate through hormones, neurons and metabolites. Our study dissects the importance of mammalian Krüppel-like factors in over all energy homeostasis. Factors controlling energy metabolism are conserved between mammals and Caenorhabditis elegans providing a new and powerful strategy to delineate the molecular pathways that lead to metabolic disorder. The C. elegans intestine is our model system where genetics, molecular biology, and cell biology are used to identify and understand genes required in fat metabolism. Thus far, we have found an important role of C. elegans KLF in FA biosynthesis, mitochondrial proliferation, lipid secretion, and β-oxidation. The mechanism by which KLF controls these events in lipid metabolism is unknown. We have recently observed that C. elegans KLF-3 selectively acts on insulin components to regulate insulin pathway activity. There are many factors that control energy homeostasis and defects in this control system are implicated in the pathogenesis of human obesity and diabetes. In this review we are discussing a role of KLF in human metabolic regulation.

Systemic administration of leptin potentiates the response of neurons in the nucleus of the solitary tract to chemoreceptor activation in the rat

Leptin microinjections into the nucleus of the solitary tract (NTS) have been shown to elicit sympathoexcitatory responses, and potentiate the cardiovascular responses to activation of the chemoreflex. In this study, experiments were done in Sprague-Dawley rats initially to provide a detailed mapping within the NTS complex of cells containing immunoreactivity to the long form of the leptin receptor (Ob-Rb). In a second series, this NTS region containing Ob-Rb immunoreactive cells was explored for single units antidromically activated by stimulation of pressor sites in the rostral ventrolateral medulla (RVLM). These antidromically identified neurons were then tested for their response to intra-carotid injections of leptin (50-100 ng/0.1 ml), and to activation of peripheral chemoreceptors following an injection of potassium cyanide (KCN) (80 μg/0.1 ml) into the carotid artery. Cells containing Ob-Rb-like immunoreactivity were found predominantly in the caudal NTS: within the medial, commissural and gelatinous (sub-postremal area) subnuclei of the NTS complex. Of 73 single units tested in these NTS regions, 48 were antidromically activated by stimulation of RVLM pressor sites and 25 of these single units responded with an increase in discharge rate after intra-carotid injections of leptin. In addition, 17 of these leptin responsive neurons were excited by the intra-carotid injections of KCN (80 μg/0.1 ml). Furthermore, the excitatory response of these single units to KCN was potentiated (59-83%) immediately following the leptin injection. These data indicate that leptin responsive neurons in NTS mediate chemoreceptor afferent information to pressor sites in the RVLM, and suggest that leptin may act as a facilitator on neuronal circuits within the NTS that potentiates the sympathoexcitatory responses elicited during the reflex activation of arterial chemoreceptors.

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

Obesity is a disease that has become a serious public health issue worldwide, and chronic stressors, which are a problem for modern society, cause neuroendocrine changes with alterations in food intake. Obesity and chronic stress are associated with the development of cardiovascular diseases and metabolic disorders. In this study, a rat model was used to evaluate the effects of a hypercaloric diet plus chronic restraint stress on the serum leptin and lipids levels and on the weight of specific adipose tissue (mesenteric, MAT; subcutaneous, SAT and visceral, VAT). Wistar rats were divided into the following 4 groups: standard chow (C), hypercaloric diet (HD), stress plus standard chow (S), and stress plus hypercaloric diet (SHD). The animals in the stress groups were subjected to chronic stress (placed inside a 25 cm × 7 cm plastic tube for 1h per day, 5 days per week for 6 weeks). The following parameters were evaluated: the weight of the liver, adrenal glands and specific adipose tissue; the delta weight; the Lee index; and the serum levels of leptin, corticosterone, glucose, total cholesterol, and triglycerides. The hypercaloric diet induced obesity in rats, increasing the Lee index, weight, leptin, triglycerides, and cholesterol levels. The stress decreased weight gain even in animals fed a hypercaloric diet but did not prevent a significant increase in the Lee index. However, an interaction between the independent factors (hypercaloric diet and stress) was observed, which is demonstrated by the increased serum leptin levels in the animals exposed to both protocols.