Identification of a Brainstem Circuit Controlling Feeding.

Hunger, driven by negative energy balance, elicits the search for and consumption of food. While this response is in part mediated by neurons in the hypothalamus, the role of specific cell types in other brain regions is less well defined. Here, we show that neurons in the dorsal raphe nucleus, expressing vesicular transporters for GABA or glutamate (hereafter, DRNVgat and DRNVGLUT3 neurons), are reciprocally activated by changes in energy balance and that modulating their activity has opposite effects on feeding-DRNVgat neurons increase, whereas DRNVGLUT3 neurons suppress, food intake. Furthermore, modulation of these neurons in obese (ob/ob) mice suppresses food intake and body weight and normalizes locomotor activity. Finally, using molecular profiling, we identify druggable targets in these neurons and show that local infusion of agonists for specific receptors on these neurons has potent effects on feeding. These data establish the DRN as an important node controlling energy balance. PAPERCLIP.

Leptin pathway is a crucial target for anthocyanins to protect against metabolic syndrome.

The high prevalence of metabolic syndrome is threatening the health of populations all over the world. Contemporary work demonstrates that high leptin concentration is directly related to the development of metabolic syndrome such as obesity, fatty liver diseases, type 2 diabetes mellitus and cardiovascular diseases. Anthocyanins are a widespread group of dietary polyphenols, which can ameliorate chronic diseases related to metabolic syndrome. In addition, anthocyanins can regulate the leptin pathway in chronic metabolic diseases, however the potential mechanism between anthocyanin and leptin is complex and elusive. In this review paper, we have evaluated the bioactivity of anthocyanins on the mediation of leptin level and the upstream and downstream pathways in chronic metabolic diseases. Anthocyanins could regulate the hypertrophy of adipose tissue, and the expression of leptin level via mediating TNF-α, C/EBP, PPAR, CREB and SREBP-1. Anthocyanins promoted the leptin sensitivity by increasing the level of leptin receptor, phosphorylation of JAK2/STAT3, PI3K/AKT, and additionally ameliorated metabolic disorder related outcome, including oxidative stress, inflammation, lipid accumulation, insulin resistance and the balance of gut microbiota. However, direct evidence of anthocyanins treatment on leptin signal transduction is still limited which calls for future molecular binding and gene regulation test.

Antibodies Reactive to Leptin in Adults with Type 2 Diabetes and Its Relationship with Clinical, Metabolic and Cardiovascular Risk Parameters.

BACKGROUND AND AIMS: Patients with obesity and type 2 diabetes (T2D) have shown alterations in the affinity of IgG anti-leptin antibodies which are possibly related to metabolic alterations. In the present exploratory study, we analyzed serum samples from adults with T2D classified by body mass index (BMI) and evaluated the relationship of IgG anti-leptin antibodies with body composition, metabolic and cardiovascular risk parameters. METHODS: Serum IgG anti-leptin antibodies (total, free and immune complexes fractions) were measured by in-house ELISA. Body composition, metabolic biomarkers (glucose, glycated hemoglobin, lipid profile, insulin, leptin) and cardiometabolic risk indexes (AIP, HOMA-IR, HOMA-ß) were evaluated in one hundred T2D patients. RESULTS: Patients with T2D and obesity presented a decrease in the percentage of IgG anti-leptin immune complexes compared to patients with T2D and overweight (p < 0.0053). Negative correlations of IgG anti-leptin immune complexes with triglycerides (TG) (r=-0.412, p = 0.023) and VLDL-C (r=-0.611, p = 0.017) were found in normal weight T2D patients. Free IgG anti-leptin antibodies correlated positively with TC (r = 0.390, p = 0.032) and LDL-C (r = 0.458, p = 0.011) in overweight individuals with T2D. Finally, total IgG anti-leptin antibodies correlated positively with leptin hormone levels (r = 0.409, p = 0.024) and negatively with HOMA-IR (r =-0.459, p = 0.012) in T2D patients with obesity. CONCLUSIONS: The decrease of IgG anti-leptin immune complexes observed in patients with T2D and obesity suggests a reduction in antibody affinity to the hormone that may impact its transport and signaling, lipid, lipoprotein and insulin metabolism.

Serum Leptin levels in newly diagnosed Epileptic Patients.

Objectives: To compare leptin levels in newly-diagnosed treatment-naive epileptic patients and healthy controls. METHODS: This case-control study was conducted from January 10 to September 15, 2022, at the Dow University of Health Sciences, Karachi, and comprised newly-diagnosed epileptic patients age 12-35years who had no comorbidity. The subjects were enrolled from the Neurology out-patient department of Civil Hospital, Karachi. Healthy individuals matched for age, gender and body mass index were also enrolled as controls. Blood samples were collected between 8am and 10am for the evaluation of serum leptin levels using enzyme-linked immunosorbent assay. Data was analysed using SPSS 26. RESULTS: Of the 100 subjects, 64(64%) were males and 36(36%) were females. There were 50(50%) cases with mean age 19.34±5.65 years, and 50(50%) controls with mean age 19.76±5.67 (p=0.614). 100% of 50 individuals in control group did not have any family history of epilepsy,while 18% of cases (9) reported a positive family history. Mean leptin level in cases was 31.03±19.37 compared to 5.25±4.03 in the controls (p<0.05). CONCLUSIONS: Serum leptin levels were elevated in newly-diagnosed epileptic patients compared to healthy controls.

Changes of the Concentration of Short-Chain Fatty Acids in the Intestines of Mice with Different Types of Obesity.

We studied the production of short-chain fatty acids (SCFA) by the intestinal microbiota in mice with obesity caused by a diet and a genetic defect in the leptin receptor gene. In mice, intestinal contents were examined and SCFA were quantitatively assayed by gas chromatography. SCFA concentration in the intestinal contents of mice with alimentary obesity model was significantly lower in the first phase of the experiment (day 14), and the change in their production in dynamics was fundamentally different from this process in the control group (standard diet). The dynamics of the concentration of these metabolites in the model of genetic obesity was similar to that in the control, but the production of SCFA was significantly reduced in mice with leptin resistance in the middle phase (day 60) of the experiment. These findings indicate that the production of SCFA is more influenced by the diet than by leptin resistance.

Actin related protein 2/3 complex subunit 1 up-regulation in the hypothalamus prevents high-fat diet induced obesity.

Obesity is a major health crisis in the modern society. Studies have shown that the consumption of a high-fat diet (HFD) induces hypothalamic inflammation and leptin resistance, which consequently favours body mass gain. Actin related protein 2/3 complex subunit 1 (ARPC1B), an actin-binding protein, is highly expressed in immune cells. Recent studies have shown that ARPC1B has a certain anti-inflammatory effect. While ARPC1B expression is decreased in the hypothalamus of mice fed a HFD, the role of ARPC1B in HFD-induced obesity remains unclear. Thus, we investigated whether ARPC1B up-regulation in the hypothalamic arcuate nucleus (ARC) could inhibit the development of obesity. Herein, ARPC1B overexpression lentiviral particles were stereotaxically injected into the ARC of male C57BL/6J mice (7 weeks old) fed with HFD. Overexpression of ARPC1B in the hypothalamic ARC attenuated HFD-induced ARC inflammation, reduced body-weight gain and feed efficiency. Furthermore, up-regulation of ARC ARPC1B improved the glucose tolerance and reduced subcutaneous/epididymal fat mass accumulation, which decreased the serum total cholesterol, serum triglyceride and leptin levels. In addition, upon ARPC1B overexpression in the hypothalamic ARC, intraperitoneal injection of leptin increased the phosphorylation level of signal transducer and activator of transcription 3 (STAT3), an important transcription factor for leptin's action, in the ARC of obese mice. Accordingly, we suggest that up-regulation of ARPC1B in the hypothalamic ARC may improve the HFD-induced hypothalamic inflammation and leptin resistance. Our findings demonstrate that ARPC1B is a promising target for the treatment of diet-induced obesity.

Leptin Signaling Could Mediate Hippocampal Decumulation of Beta-Amyloid and Tau Induced by High-Intensity Interval Training in Rats with Type 2 Diabetes.

Leptin (LEP) can cross the blood-brain barrier and facilitate cross-talk between the adipose tissue and central nerve system (CNS). This study aimed to investigate the effect of 8-week high-intensity interval training (HIIT) on the LEP signaling in the hippocampus of rats with type 2 diabetes. 20 rats were randomly divided into four groups: (i) control (Con), (ii) type 2 diabetes (T2D), (iii) exercise (EX), and (iv) type 2 diabetes + exercise (T2D + EX). The rats in the T2D and T2D + EX were fed a high-fat diet for two months, then a single dose of STZ (35 mg/kg) was injected to induce diabetes. The EX and T2D + EX groups performed 4-10 intervals of treadmill running at 80-100% of Vmax. Serum and hippocampal levels of LEP as well as hippocampal levels of LEP receptors (LEP-R), Janus kinase 2 (JAK-2), signal transducer and activator of transcription 3 (STAT-3), activated protein kinase (AMP-K), proxy zoster receptor α (PGC-1α), beta-secretase 1 (BACE1), Beta-Amyloid (Aß), Phosphoinositide 3-kinases (PI3K), protein kinase B (AKT), mammalian target of rapamycin (mTOR), Glycogen Synthase Kinase 3 Beta (GSK3ß), and hyperphosphorylated tau proteins (TAU) were measured. One-way ONOVA and Tukey post-hoc tests were used to analyze the data. Serum and hippocampal levels of LEP as well as hippocampal levels of LEP-R, JAK-2, STAT-3, AMP-K, PGC1α, PI3K, AKT, and mTOR were increased while hippocampal levels of BACE1, GSK3B, TAU, and Aß were decreased in T2D + EX compared with T2D group. Serum LEP and hippocampal levels of LEP, LEP-R, JAK-2, STAT-3, AMP-K, PGC1α, PI3K, AKT, and mTOR were decreased. Conversely hippocampal levels of BACE1, GSK3B, TAU, and Aß were increased in T2D group compared with CON group. HIIT could improve LEP signaling in the hippocampus of rats with type 2 diabetes and decrease the accumulation of Tau and Aß, which may reduce the risk of memory impairments.

High Intensity Interval Training can Ameliorate Hypothalamic Appetite Regulation in Male Rats with Type 2 Diabetes: The Role of Leptin.

Disruption of leptin (LEP) signaling in the hypothalamus caused by type 2 diabetes (T2D) can impair appetite regulation. The aim of this study was to investigate whether the improvement in appetite regulation induced by high-intensity interval training (HIIT) in rats with T2D can be mediated by LEP signaling. In this study, 20 male Wister rats were randomly assigned to one of four groups: CO (non-type 2 diabetes control), T2D (type 2 diabetes), EX (non-type 2 diabetes exercise), and T2D + EX (type 2 diabetes + exercise).To induce T2D, a combination of a high-fat diet for 2 months and a single dose of streptozotocin (35 mg/kg) was administered. Rats in the EX and T2D + EX groups performed 4-10 intervals of treadmill running at 80-100% of their maximum velocity (Vmax). Homeostatic Model Assessment for Insulin Resistance (HOMA-IR), serum levels of insulin (INS) and LEP (LEPS) as well as hypothalamic expression of LEP receptors (LEP-R), Janus kinase 2 (JAK-2), signal transducer and activator of transcription 3 (STAT-3), neuropeptide Y (NPY), agouti-related protein (AGRP), pro-opiomelanocortin cocaine (POMC), amphetamine-related transcript (CART), suppressor of cytokine signaling (SOCS3), forkhead box protein O1 (FOXO1) were assessed. ANOVA and Tukey post hoc tests were used to compare the results between the groups. The levels of LEPS and INS, as well as the levels of LEP-R, JAK-2, STAT-3, POMC, and CART in the hypothalamus were found to be higher in the T2D + EX group compared to the T2D group. On the other hand, the levels of HOMA-IR, NPY, AGRP, SOCS3, and FOXO1 were lower in the T2D + EX group compared to the T2D group (P < 0.0001). The findings of this study suggest that HIIT may improve appetite regulation in rats with T2D, and LEP signaling may play a crucial role in this improvement. Graphical abstract (leptin signaling in the hypothalamus), Leptin (LEP), Leptin receptor (LEP-R), Janus kinase 2 (JAK2), Signal transducer and activator of transcription 3 (STAT3), expressing Neuropeptide Y (NPY), Agouti-related protein (AGRP), anorexigenic neurons (expressing pro-opiomelanocortin cocaine (POMC), Amphetamine-related transcript (CART), suppressor of cytokine signaling (SOCS3), forkhead box protein O1 (FOXO1).

A Potential Link Between Visceral Obesity and Risk of Alzheimer's Disease.

Alzheimer's disease (AD) is the most common type of dementia characterized by the deposition of amyloid beta (Aß) plaques and tau-neurofibrillary tangles in the brain. Visceral obesity (VO) is usually associated with low-grade inflammation due to higher expression of pro-inflammatory cytokines by adipose tissue. The objective of the present review was to evaluate the potential link between VO and the development of AD. Tissue hypoxia in obesity promotes tissue injury, production of adipocytokines, and release of pro-inflammatory cytokines leading to an oxidative-inflammatory loop with induction of insulin resistance. Importantly, brain insulin signaling is involved in the pathogenesis of AD and lower cognitive function. Obesity and enlargement of visceral adipose tissue are associated with the deposition of Aß. All of this is consonant with VO increasing the risk of AD through the dysregulation of adipocytokines which affect the development of AD. The activated nuclear factor kappa B (NF-κB) pathway in VO might be a potential link in the development of AD. Likewise, the higher concentration of advanced glycation end-products in VO could be implicated in the pathogenesis of AD. Taken together, different inflammatory signaling pathways are activated in VO that all have a negative impact on the cognitive function and progression of AD except hypoxia-inducible factor 1 which has beneficial and neuroprotective effects in mitigating the progression of AD. In addition, VO-mediated hypoadiponectinemia and leptin resistance may promote the progression of Aß formation and tau phosphorylation with the development of AD. In conclusion, VO-induced AD is mainly mediated through the induction of oxidative stress, inflammatory changes, leptin resistance, and hypoadiponectinemia that collectively trigger Aß formation and neuroinflammation. Thus, early recognition of VO by visceral adiposity index with appropriate management could be a preventive measure against the development of AD in patients with VO.

Effects of saturated versus unsaturated fatty acids on metabolism, gliosis, and hypothalamic leptin sensitivity in male mice.

BACKGROUND: Development of obesity and its comorbidities is not only the result of excess energy intake, but also of dietary composition. Understanding how hypothalamic metabolic circuits interpret nutritional signals is fundamental to advance towards effective dietary interventions. OBJECTIVE: We aimed to determine the metabolic response to diets enriched in specific fatty acids. METHODS: Male mice received a diet enriched in unsaturated fatty acids (UOLF) or saturated fatty acids (SOLF) for 8 weeks. RESULTS: UOLF and SOLF mice gained more weight and adiposity, but with no difference between these two groups. Circulating leptin levels increased on both fatty acid-enriched diet, but were higher in UOLF mice, as were leptin mRNA levels in visceral adipose tissue. In contrast, serum non-esterified fatty acid levels only rose in SOLF mice. Hypothalamic mRNA levels of NPY decreased and of POMC increased in both UOLF and SOLF mice, but only SOLF mice showed signs of hypothalamic astrogliosis and affectation of central fatty acid metabolism. Exogenous leptin activated STAT3 in the hypothalamus of all groups, but the activation of AKT and mTOR and the decrease in AMPK activation in observed in controls and UOLF mice was not found in SOLF mice. CONCLUSIONS: Diets rich in fatty acids increase body weight and adiposity even if energy intake is not increased, while increased intake of saturated and unsaturated fatty acids differentially modify metabolic parameters that could underlie more long-term comorbidities. Thus, more understanding of how specific nutrients affect metabolism, weight gain, and obesity associated complications is necessary.

High tissue-sodium associates with systemic inflammation and insulin resistance in obese individuals.

BACKGROUND AND AIMS: High sodium intake is associated with obesity and insulin resistance, and high extracellular sodium content may induce systemic inflammation, leading to cardiovascular disease. In this study, we aim to investigate whether high tissue sodium accumulation relates with obesity-related insulin resistance and whether the pro-inflammatory effects of excess tissue sodium accumulation may contribute to such association. METHODS AND RESULTS: In a cross-sectional study of 30 obese and 53 non-obese subjects, we measured insulin sensitivity determined as glucose disposal rate (GDR) using hyperinsulinemic euglycemic clamp, and tissue sodium content using 23Na magnetic resonance imaging. Median age was 48 years, 68% were female and 41% were African American. Median (interquartile range) BMI was 33 (31.5, 36.3) and 25 (23.5, 27.2) kg/m2 in the obese and non-obese individuals, respectively. In obese individuals, insulin sensitivity negatively correlated with muscle (r = -0.45, p = 0.01) and skin sodium (r = -0.46, p = 0.01). In interaction analysis among obese individuals, tissue sodium had a greater effect on insulin sensitivity at higher levels of high-sensitivity C-reactive protein (p-interaction = 0.03 and 0.01 for muscle and skin Na+, respectively) and interleukin-6 (p-interaction = 0.024 and 0.003 for muscle and skin Na+, respectively). In interaction analysis of the entire cohort, the association between muscle sodium and insulin sensitivity was stronger with increasing levels of serum leptin (p-interaction = 0.01). CONCLUSIONS: Higher muscle and skin sodium are associated with insulin resistance in obese patients. Whether high tissue sodium accumulation has a mechanistic role in the development of obesity-related insulin resistance through systemic inflammation and leptin dysregulation remains to be examined in future studies. CLINICALTRIALS: gov registration: NCT02236520.

Association of a high-fat diet with I-FABP as a biomarker of intestinal barrier dysfunction driven by metabolic changes in Wistar rats.

BACKGROUND: The epithelial lining of the gut expresses intestinal fatty-acid binding proteins (I-FABPs), which increase in circulation and in plasma concentration during intestinal damage. From the perspective of obesity, the consumption of a diet rich in fat causes a disruption in the integrity of the gut barrier and an increase in its permeability. HYPOTHESIS: There is an association between the expression of I-FABP in the gut and various metabolic changes induced by a high-fat (HF) diet. METHODS: Wistar albino rats (n = 90) were divided into three groups (n = 30 per group), viz. One control and two HF diet groups (15 and 30%, respectively) were maintained for 6 weeks. Blood samples were thus collected to evaluate the lipid profile, blood glucose level and other biochemical tests. Tissue sampling was conducted to perform fat staining and immunohistochemistry. RESULTS: HF diet-fed rats developed adiposity, insulin resistance, leptin resistance, dyslipidemia, and increased expression of I-FABP in the small intestine compared to the control group. Increased I-FABP expression in the ileal region of the intestine is correlated significantly with higher fat contents in the diet, indicating that higher I-FABP expression occurs due to increased demand of enterocytes to transport lipids, leading to metabolic alterations. CONCLUSION: In summary, there is an association between the expression of I-FABP and HF diet-induced metabolic alterations, indicating that I-FABP can be used as a biomarker for intestinal barrier dysfunction.

Safflower yellow and its main component hydroxysafflor yellow A alleviate hyperleptinemia in diet-induced obesity mice through a dual inhibition of the GIP-GIPR signaling axis.

Glucose-dependent insulinotropic polypeptide (GIP) is a gastrointestinal hormone secreted by K cells in the small intestine and is considered an obesity-promoting factor. In this study, we systematically investigated the anti-obesity effects of intragastric safflower yellow (SY)/hydroxysafflor yellow A (HSYA) and the underlying mechanism for the first time. Our results showed that intragastric SY/HSYA, rather than an intraperitoneal injection, notably decreased serum GIP levels and GIP staining in the small intestine in diet-induced obese (DIO) mice. Moreover, intragastric SY/HSYA was also first found to significantly suppress GIP receptor (GIPR) signaling in both the hypothalamus and subcutaneous White adipose tissue. Our study is the first to show that intragastric SY/HSYA obviously reduced food intake and body weight gain in leptin sensitivity experiments and decreased serum leptin levels in DIO mice. Further experiments demonstrated that SY treatment also significantly reduced leptin levels, whereas the inhibitory effect of SY on leptin levels was reversed by activating GIPR in 3 T3-L1 adipocytes. In addition, intragastric SY/HSYA had already significantly reduced serum GIP levels and GIPR expression before the serum leptin levels were notably changed in high-fat-diet-fed mice. These findings suggested that intragastric SY/HSYA may alleviate diet-induced obesity in mice by ameliorating hyperleptinemia via dual inhibition of the GIP-GIPR axis.

Influence of Leptin on the Secretion of Growth Hormone in Ewes under Different Photoperiodic Conditions.

Leptin is an adipokine with a pleiotropic impact on many physiological processes, including hypothalamic-pituitary-somatotropic (HPS) axis activity, which plays a key role in regulating mammalian metabolism. Leptin insensitivity/resistance is a pathological condition in humans, but in seasonal animals, it is a physiological adaptation. Therefore, these animals represent a promising model for studying this phenomenon. This study aimed to determine the influence of leptin on the activity of the HPS axis. Two in vivo experiments performed during short- and long-day photoperiods were conducted on 12 ewes per experiment, and the ewes were divided randomly into 2 groups. The arcuate nucleus, paraventricular nucleus, anterior pituitary (AP) tissues, and blood were collected. The concentration of growth hormone (GH) was measured in the blood, and the relative expression of GHRH, SST, GHRHR, SSTR1, SSTR2, SSTR3, SSTR5, LEPR, and GH was measured in the collected brain structures. The study showed that the photoperiod, and therefore leptin sensitivity, plays an important role in regulating HPS axis activity in the seasonal ewe. However, leptin influences the release of GH in a season-dependent manner, and its effect seems to be targeted at the posttranscriptional stages of GH secretion.

Leptin Increases: Physiological Roles in the Control of Sympathetic Nerve Activity, Energy Balance, and the Hypothalamic-Pituitary-Thyroid Axis.

It is well established that decreases in plasma leptin levels, as with fasting, signal starvation and elicit appropriate physiological responses, such as increasing the drive to eat and decreasing energy expenditure. These responses are mediated largely by suppression of the actions of leptin in the hypothalamus, most notably on arcuate nucleus (ArcN) orexigenic neuropeptide Y neurons and anorexic pro-opiomelanocortin neurons. However, the question addressed in this review is whether the effects of increased leptin levels are also significant on the long-term control of energy balance, despite conventional wisdom to the contrary. We focus on leptin's actions (in both lean and obese individuals) to decrease food intake, increase sympathetic nerve activity, and support the hypothalamic-pituitary-thyroid axis, with particular attention to sex differences. We also elaborate on obesity-induced inflammation and its role in the altered actions of leptin during obesity.

Overview and New Insights into the Metabolic Syndrome: Risk Factors and Emerging Variables in the Development of Type 2 Diabetes and Cerebrocardiovascular Disease.

Metabolic syndrome (MetS) is considered a metabolic disorder that has been steadily increasing globally and seems to parallel the increasing prevalence of obesity. It consists of a cluster of risk factors which traditionally includes obesity and hyperlipidemia, hyperinsulinemia, hypertension, and hyperglycemia. These four core risk factors are associated with insulin resistance (IR) and, importantly, the MetS is known to increase the risk for developing cerebrocardiovascular disease and type 2 diabetes mellitus. The MetS had its early origins in IR and syndrome X. It has undergone numerous name changes, with additional risk factors and variables being added over the years; however, it has remained as the MetS worldwide for the past three decades. This overview continues to add novel insights to the MetS and suggests that leptin resistance with hyperleptinemia, aberrant mitochondrial stress and reactive oxygen species (ROS), impaired folate-mediated one-carbon metabolism with hyperhomocysteinemia, vascular stiffening, microalbuminuria, and visceral adipose tissues extracellular vesicle exosomes be added to the list of associated variables. Notably, the role of a dysfunctional and activated endothelium and deficient nitric oxide bioavailability along with a dysfunctional and attenuated endothelial glycocalyx, vascular inflammation, systemic metainflammation, and the important role of ROS and reactive species interactome are discussed. With new insights and knowledge regarding the MetS comes the possibility of new findings through further research.

Leptin-reactive antibodies are distinctly correlated with body composition parameters and metabolic risk indexes in children and adolescents.

Studies have demonstrated the presence of low-affinity immunoglobulins (Igs) directed to leptin, a key hormone of the neuroendocrine axis that regulates appetite and metabolism, in adult healthy subjects, patients with obesity, and type 2 diabetes mellitus. In the present exploratory study, IgG leptin-reactive antibodies were analyzed for the first time in children and adolescents according to body mass index (BMI) and were correlated with biochemical profile (lipid profile, insulin, glucose, and leptin) and metabolic risk indexes [homeostasis model assessment for insulin resistance (HOMA-IR), homeostasis model assessment for ß-cell function (HOMA-ß), atherogenic index of plasma (AIP)]. One hundred and thirty-six participants were included (children n = 63, adolescents n = 73). An in-house enzyme-linked immunosorbent assay (ELISA) test was performed to measure IgG anti-leptin antibodies (free, total, and immune complexes). In adolescents, free and total IgG anti-leptin antibodies levels were higher in groups with overweight or obesity than in normal-weight group (P < 0.01), while in children, the total fractions were lower in groups with overweight and obesity than in normal weight (P < 0.02). Immune complexes percentage showed opposite correlations with BMI in children (r = 0.4004, P = 0.0473) and adolescents (r = -0.3983, P = 0.0133). IgG anti-leptin antibodies were also correlated with HOMA-IR in children (r = -0.4569, P = 0.0217) and adolescents (r = -0.3589, P = 0.0316), and with AIP (r = -0.3608, P = 0.0261) in adolescents. Our data suggest that the production and affinity of IgG anti-leptin antibodies can be affected by age, body composition, and metabolic conditions; additionally, in normal conditions, IgG anti-leptin antibodies may have a protective role in insulin resistance and cardiovascular events.

Leptin, the brain and energy homeostasis: From an apparently simple to a highly complex neuronal system.

Leptin, produced and secreted by white adipose tissue in tight relationship with adipose mass, informs the brain about the status of the energy stores serving as the main peripheral signal for energy balance regulation through interaction with a multitude of highly interconnected neuronal populations. Most obese patients display resistance to the anorectic effect of the hormone. The present review unravels the multiple levels of complexity that trigger hypothalamic response to leptin with the objective of highlighting those critical hubs that, mainly in the hypothalamic arcuate nucleus, may undergo obesity-induced alterations and create an obstacle to leptin action. Several mechanisms underlying leptin resistance have been proposed, possibly representing useful targets to empower leptin effects. Among these, a special focus is herein dedicated to detail how leptin gains access into the brain and how neuronal plasticity may interfere with leptin function.

Gestational weight gain, appetite regulating hormones, and metformin treatment in polycystic ovary syndrome: A longitudinal, placebo-controlled study.

OBJECTIVE: To explore mechanisms that modulate gestational weight gain (GWG) in women with polycystic ovary syndrome (PCOS) and healthy controls. DESIGN: Sub-sample of randomised controlled trials (PCOS) combined with a prospective cohort (controls). SETTING: Eleven Norwegian, Swedish, and Icelandic hospitals. POPULATION: Pregnant women with PCOS treated with metformin (PCOS-M, n = 36) or placebo (PCOS-P, n = 37), and healthy pregnant women (HC, n = 15). METHODS: Serum levels of the appetite regulating hormones leptin, ghrelin, allopregnanolone, and soluble leptin receptor (sOB-R) were determined in the first and third trimesters. MAIN OUTCOME MEASURES: Excessive GWG (eGWG) relative to body mass index according to Institute of Medicine (IOM) guideline. Serum leptin/sOB-R ratio, or free-leptin-index (FLI), as biomarker of leptin sensitivity. Serum ghrelin and allopregnanolone levels. RESULTS: The overall prevalence of eGWG was 44% (38/86). Women with eGWG had higher first and third trimester FLI (P < 0.001), and lower third trimester allopregnanolone levels (P = 0.003) versus women with non-eGWG. The prevalence of eGWG was lower in PCOS-M versus PCOS-P (28% versus 62%, odds ratio = 0.4, 95% CI 0.2-0.8, P = 0.005). FLI decreased during pregnancy in PCOS-M (P = 0.01), but remained unaltered in PCOS-P and HC. Ghrelin and allopregnanolone levels were comparable in PCOS-M, PCOS-P and HC throughout pregnancy. CONCLUSION: Excessive GWG is associated with enhanced leptin resistance, and attenuated physiological increase in serum allopregnanolone levels during pregnancy. Metformin reduces the risk for eGWG and improves leptin sensitivity in pregnant women with PCOS. TWEETABLE ABSTRACT: Metformin counteracts excessive weight gain and leptin resistance in pregnant women with polycystic ovary syndrome.

The interaction between rs 3,807,992 genotypes with the dietary inflammatory index on Leptin, Leptin resistance, and Galectin 3 in obese and overweight women.

OBJECTIVE: Obesity is related to increasing leptin and some inflammatory factors that are associated with low-grade inflammation. Moreover, several studies have shown Caveolin-1 (CAV1) genetic variations may be associated with dietary intake. The current study aimed to evaluate the interaction of CAV1 rs3807992 with types of the energy-adjusted dietary inflammatory index (EDII) in leptin, leptin resistance, and Galectin 3, as inflammatory factors. METHODS: This cross-sectional study was carried out on 363 overweight and obese females. Dietary intake and DII were obtained from a 147-item food frequency questionnaire (FFQ). The CAV-1 genotype was measured using the PCR-RFLP method. Anthropometric values and serum levels of leptin and Galectin 3 were measured by standard methods. RESULTS: Increased adherence to EDII in the interaction with CAV1 genotypes led to an increase in leptin level 79.15 (mg/l) (ß = 79.15, CI = - 1.23,163.94, P = 0.04) in model 3, after controlling for further potential confounders. By contrast, adherence to EDII in the interaction with the genotype including risk alleles showed no significant interaction, even after adjustment in model 3 (ß = 0.55, CI = - 0.99, 2.09, P = 0.48). Although, a marginal positive significant interaction was found between EDII and CAV1 genotypes on Galectin 3, after adjustment in model 3 (ß = 31.35, CI = 0.13, 77.13, P = 0.05). CONCLUSIONS: The present study indicates that a high adherence of EDII and CAV1 genotypes containing risk alleles may be a prognostic factor and increase both leptin and Galectin3. However, it seems that the presence of interaction was not on leptin resistance. Further functional studies are necessary to elucidate the exact mechanism.