Diverse roles of leptin in the gastrointestinal tract: modulation of motility, absorption, growth, and inflammation

Obesity and leptin in breast cancer angiogenesis

At the time of breast cancer diagnosis, most patients meet the diagnostic criteria to be classified as obese or overweight. This can significantly impact patient outcome: breast cancer patients with obesity (body mass index > 30) have a poorer prognosis compared to patients with a lean BMI. Obesity is associated with hyperleptinemia, and leptin is a well-established driver of metastasis in breast cancer. However, the effect of hyperleptinemia on angiogenesis in breast cancer is less well-known. Angiogenesis is an important process in breast cancer because it is essential for tumor growth beyond 1mm3 in size as well as cancer cell circulation and metastasis. This review investigates the role of leptin in regulating angiogenesis, specifically within the context of breast cancer and the associated tumor microenvironment in obese patients.

Are adipokines related to COVID-19 and its severity? A systematic review and meta-analysis

Introduction

The relationship between several adipokines and COVID-19 severity has lately been evaluated, results being inconclusive. Therefore, we aimed to assess the association between adipokines in COVID-19 and its severity.

Methods

A search was performed in PubMed, Scopus, and Embase using predefined keywords. The Newcastle of Ottawa Scale (NOS) was used for the quality assessment of included studies. The main summary outcome was the mean difference (MD) in adipokine levels.

Results

A total of 8 studies involving 473 individuals were included. A significant MD in serum adiponectin levels was demonstrated in mild vs. severe COVID-19 patients (-5.734 [95% CI -11.215 - -0.252]), with no significant MD in mild vs. moderate (-7.117 [95% CI -19.546 - 5.313]), or moderate vs. severe COVID-19 (-1.846 [95% CI -4.516 - 0.824]). Moreover, no significant MD was found in adiponectin and leptin levels when comparing COVID-19 patients vs. controls (-12.675 [95% CI -36.159 - 10.808]) and (8.034 [95% CI -10.403 - 26.471]), respectively.

Conclusion

Adiponectin levels were significantly increased in patients with severe compared to mild COVID-19. However, no significant MD was found in adiponectin levels in mild vs. moderate and moderate vs. severe COVID-19 patients, nor in adiponectin and leptin levels in COVID-19 patients vs. controls.

Adiponectin affects ileal contractility of mouse preparations

Adiponectin (ADPN) has been reported to induce inhibitory effects on gastric motor activity, which, being a source of peripheral satiety signals, would contribute to the central anorexigenic effects of the hormone in rodents. However, peripheral satiety signals can also originate from the small intestine. Since there are no data on the effects of ADPN in this gut region, the present study aimed to investigate whether ADPN affects murine ileal contractility. Immunofluorescence experiments and Western blot were also performed to reveal the expression of ADPN receptors. Mechanical responses of ileal preparations were recorded in vitro via force-displacement transducers. Preparations showed a tetrodotoxin- and atropine-insensitive spontaneous contractile activity. Electrical field stimulation (EFS) induced tetrodotoxin- and atropine-sensitive contractile responses. ADPN induced a decay of the basal tension and decreased the amplitude of either the spontaneous contractility or the EFS-induced excitatory responses. All ADPN effects were abolished by the nitric oxide (NO) synthesis inhibitor NG-nitro l-arginine. The expression of the ADPN receptor, AdipoR1, but not AdipoR2, was also revealed in enteric glial cells. The present results offer the first evidence that ADPN acts on ileal preparations. The hormone exerts inhibitory effects, likely involving AdipoR1 on enteric glial cells and NO. From a physiological point of view, it could be hypothesized that the depressant action of ADPN on ileal contractility represents an additional peripheral satiety signal which, as also described for the ileal brake, could contribute to the central anorexigenic effects of the hormone.NEW & NOTEWORTHY This study provides the first evidence that adiponectin (ADPN) is able to act on ileal preparations. Functional results demonstrate that the hormone, other than causing a slight decay of the basal tension, depresses the amplitude of both spontaneous contractility and neurally induced excitatory responses of the mouse ileum through the involvement of nitric oxide. The expression of the ADPN receptor AdipoR1 and its localization on glial cells was revealed by Western blot and immunofluorescence analysis.

Enhancing Oral Delivery of Biologics: A Non-Competitive and Cross-Reactive Anti-Leptin Receptor Nanofitin Demonstrates a Gut-Crossing Capacity in an Ex Vivo Porcine Intestinal Model

Biotherapeutics exhibit high efficacy in targeted therapy, but their oral delivery is impeded by the harsh conditions of the gastrointestinal (GI) tract and limited intestinal absorption. This article presents a strategy to overcome the challenges of poor intestinal permeability by using a protein shuttle that specifically binds to an intestinal target, the leptin receptor (LepR), and exploiting its capacity to perform a receptor-mediated transport. Our proof-of-concept study focuses on the characterization and transport of robust affinity proteins, known as Nanofitins, across an ex vivo porcine intestinal model. We describe the potential to deliver biologically active molecules across the mucosa by fusing them with the Nanofitin 1-F08 targeting the LepR. This particular Nanofitin was selected for its absence of competition with leptin, its cross-reactivity with LepR from human, mouse, and pig hosts, and its shuttle capability associated with its ability to induce a receptor-mediated transport. This study paves the way for future in vivo demonstration of a safe and efficient oral-to-systemic delivery of targeted therapies.

Expression of Genes Encoding Selected Orexigenic and Anorexigenic Peptides and Their Receptors in the Organs of the Gastrointestinal Tract of Calves and Adult Domestic Cattle (Bos taurus taurus)

The regulation of food intake occurs at multiple levels, and two of the components of this process are orexigenic and anorexigenic peptides, which stimulate or inhibit appetite, respectively. The study of the function of these compounds in domestic cattle is essential for production efficiency, animal welfare, and health, as well as for economic benefits, environmental protection, and the contribution to a better understanding of physiological aspects that can be applied to other species. In this study, the real-time PCR method was utilized to determine the expression levels of GHRL, GHSR, SMIM20, GPR173, LEP, LEPR, and NUCB2 (which encode ghrelin, its receptor, phoenixin-14, its receptor, leptin, its receptor, and nesfatin-1, respectively) in the gastrointestinal tract (GIT) of Polish Holstein-Friesian breed cattle. In all analyzed GIT segments, mRNA for all the genes was present in both age groups, confirming their significance in these tissues. Gene expression levels varied distinctly across different GIT segments and between young and mature subjects. The differences between calves and adults were particularly pronounced in areas such as the forestomachs, ileum, and jejunum, indicating potential changes in peptides regulating food intake based on the developmental phase. In mature individuals, the forestomachs predominantly displayed an increase in GHRL expression, while the intestines had elevated levels of GHSR, GPR173, LEP, and NUCB2. In contrast, the forestomachs in calves showed upregulated expressions of LEP, LEPR, and NUCB2, highlighting the potential importance of peptides from these genes in bovine forestomach development.

Gastrointestinal Biomarkers and Their Association with Feeding in the First Five Days of Pediatric Critical Illness

OBJECTIVES

Predicting the patients' tolerance to enteral nutrition (EN) would help clinicians optimize individual nutritional intake. This study investigated the course of several gastrointestinal (GI) biomarkers and their association with EN advancement (ENA) longitudinally during pediatric intensive care unit (PICU) admission.

METHODS

This is a secondary analysis of the Early versus Late Parenteral Nutrition in the Pediatric Intensive Care Unit randomized controlled trial. EN was started early and increased gradually. The cholecystokinin (CCK), leptin, glucagon, intestinal fatty acid-binding protein 2 (I-FABP2), and citrulline plasma concentrations were measured upon PICU admission, day 3 and day 5. ENA was defined as kcal EN provided as % of predicted resting energy expenditure. The course of the biomarkers and ENA was examined in patients with samples on all time points using Friedman and Wilcoxon signed-rank tests. The association of ENA with the biomarkers was examined using a 2-part mixed-effects model with data of the complete population, adjusted for possible confounders.

RESULTS

For 172 patients, median age 8.6 years (first quartile; third quartile: 4.2; 13.4), samples were available, of which 55 had samples on all time points. The median ENA was 0 (0; 0) on admission, 14.5 (0.0; 43.8) on day 3, and 28.0 (7.6; 94.8) on day 5. During PICU stay, CCK and I-FABP2 concentrations decreased significantly, whereas glucagon concentrations increased significantly, and leptin and citrulline remained stable. None of the biomarkers was longitudinally associated with ENA.

CONCLUSIONS

Based on the current evidence, CCK, leptin, glucagon, I-FABP2, and citrulline appear to have no added value in predicting ENA in the first 5 days of pediatric critical illness.

Peroral Endoscopic Myotomy for Achalasia after Bariatric Surgery: A Case Report and Review of the Literature

INTRODUCTION

Achalasia following bariatric surgery is a rare phenomenon with diverse potential physiopathological origins.

AIMS

This article aims to explore the hypothetical physiopathological connection between bariatric surgery and the subsequent onset of achalasia.

MATERIAL AND METHODS

A review was conducted to identify studies reporting cases of peroral endoscopic myotomy (POEM) after bariatric procedures and detailing the outcomes in terms of the technical and clinical success. Additionally, a case of a successful POEM performed on a patient two years after undergoing laparoscopic sleeve gastrectomy (LSG) is presented.

RESULTS

The selection criteria yielded eight studies encompassing 40 patients treated with POEM for achalasia after bariatric surgery: 34 after Roux-en-Y gastric bypass (RYGB) and 6 after LSG. The studies reported an overall technical success rate of 97.5%, with clinical success achieved in 85% of cases. Adverse events were minimal, with only one case of esophageal leak treated endoscopically. However, a postprocedural symptomatic evaluation was notably lacking in most of the included studies.

CONCLUSIONS

Achalasia poses a considerable challenge within the bariatric surgery population. POEM has emerged as a technically viable and safe intervention for this patient demographic, providing an effective treatment option where surgical alternatives for achalasia are limited. Our findings highlight the promising outcomes of POEM in these patients, but the existing data remain limited. Hence, prospective studies are needed to elucidate the optimal pre-surgical assessment and timing of endoscopic procedures for optimizing outcomes.

Effects of fresh vs dried mango consumption on satiety and postprandial glucose in healthy adults

Mango is a widely favored fruit that offers high nutritional value. Mango has been studied to examine its influence on postprandial glucose, but few studies have used fresh mango compared to dried mango to measure blood glucose and satiety after consumption. Therefore, the objective of the present study was to investigate the effects of fresh versus dried mango consumption on satiety and postprandial glucose. A crossover design was implemented where 34 healthy adults (29 females and 5 males; 25.0 ± 6.0 years; BMI 23.8 ± 4.3 kg/m²) consumed either 100 kcal of fresh mango, dried mango, or white bread on three separate occasions. Following consumption, satiety was assessed every 15 min for 90 min and blood glucose was assessed every 30 min for 90 min. Consumption of fresh mango results showed a significant increase in satiety (tendency of greater fullness (P = 0.073) and less desire to eat (P < 0.05)) in participants. Fresh mango exhibited a more efficient decrease in postprandial glucose levels (P < 0.05) compared to dried mango or white bread, and fresh mango promoted a greater stability in blood glucose. Dried mango consumption also significantly lowered postprandial glucose compared to white bread (P < 0.05). These results suggest that fresh mango consumption may be beneficial in improving satiety responses and postprandial glucose control when compared to its dried alternative or white bread. The results of the study may help guide individuals who are overweight or obese and/or have type 2 diabetes by altering their food choices that ultimately could improve their health. ClinicalTrials.gov Identifier: NCT03956602.

Leptin system is not affected by different diets in the abomasum of the sheep reared in semi-natural pastures of the Central Apennines

The growing summer drought stress is affecting the nutritional value of pastures, no longer sufficient to support the nutritional status of sheep in extensive rearing. Adipokines affect organ and tissue functionality can be useful to evaluate animal welfare and prompt an improvement in the management of the grazing animals. Leptin (Lep) is an adipokine mainly produced by adipose tissue that regulates food intake by an anorexigenic action. Lep has also been detected in the human and rat gastrointestinal tract, where it regulates the rate of gastric emptying. In this study, Lep system was evaluated in the abomasum of 15 adult sheep reared on Apennine pastures and subjected to different diets. Until the maximum pasture flowering (MxF group), the sheep fed on fresh forage; from that moment until the maximum pasture dryness (MxD group), the experimental group (Exp group) received a feed supplementation in addition to MxD group feeding. The Lep system was investigated in the abomasum samples by immunohistochemistry (IHC) and RT-qPCR. Double-label localisation of Lep and leptin receptor (LepR) with neuroendocrine hormones was conducted to distinguish the gland cell types. The analysis performed revealed the presence of Lep and LepR in the chief and neuroendocrine cells of the fundic glands of the abomasum. RT-qPCR evidenced the transcript for Lep and LepR also identifying the long isoform (LepRb). No significant differences were observed among the three groups of sheep subjected to different diets. The abundant immunostaining observed in the fundic glands suggests that the Lep intervenes in the regulation of abomasum in sheep with a similar pattern to monogastric species while long term food supplementation seems do not influence the local function of the Lep system. A better understanding of the gastrointestinal system can contribute to improving sheep management and optimising the sustainability of livestock production.

Rapid Emergence of Appetite and Hunger Resulting in Weight Gain and Improvement of Eating Disorder Symptomatology during and after Short-Term Off-Label Metreleptin Treatment of a Patient with Anorexia Nervosa

Off-label treatment of a 15-year-old female patient with anorexia nervosa (AN) with human recombinant leptin (metreleptin) for nine days was associated with self-reported increments of appetite and hunger resulting in rapid weight gain and substantial improvement of eating disorder cognitions and of depression. The results further substantiate the effects of metreleptin on both AN and depression. We contrast these results with the widespread view that leptin is an anorexigenic hormone. Randomized controlled trials are warranted to confirm the described effects.

Neuronal Nitric Oxide Synthase as a Shared Target for the Effects of Adiponectin and Resistin on the Mechanical Responses of the Mouse Gastric Fundus

It has been reported that adiponectin (ADPN) and resistin are co-secreted by white mouse adipocytes and exert similar inhibitory effects in the mouse gastric fundus, in which resistin was observed to increase neuronal nitric oxide synthase (nNOS) expression. On these grounds, the present work aimed to investigate whether the effects of the two adipokines on the neurally-induced relaxant responses potentiate each other and whether there is a possible correlation with changes in nNOS expression in preparations from the mouse gastric fundus. In carbachol (CCh)-precontracted strips, electrical field stimulation elicited nitrergic relaxant responses, whose amplitude was increased by ADPN or resistin, but no additional enhancements were observed in their concomitant presence. Western blot and immunofluorescence analyses revealed that ADPN, like resistin, was able to up-regulate nNOS expression and to increase the percentage of nNOS-positive neurons in the myenteric plexus: co-treatment with the two adipokines did not induce additional changes. The results indicate that the two adipokines modulate nitrergic neurotransmission, and both do so by up-regulating nNOS expression. Therefore, nNOS appears to be a shared target for the two adipokines' effects, which, rather than mutually reinforcing each other, may represent a dual physiological control mechanism to guarantee gastric fundus relaxation.

Colonic bowel prep and body mass index: does one size fit all? A multi-centre review

PURPOSE

To investigate whether body mass index (BMI) is a risk factor for inadequate bowel preparation in elective colonoscopy. The null hypothesis being BMI does not affect bowel preparation adequacy.

METHODS

A retrospective cohort study of all participants with complete medical records who had an elective colonoscopy was conducted across three tertiary teaching hospitals in Perth, Western Australia, from January 2016 to July 2019. Participants were separated into BMI subgroups of healthy weight, overweight and obese (≥ 30 kg/m²). Data were extracted from medical records, colonoscopy and histopathology reports and were analysed using SPSS v.27.

RESULTS

Of the 1082 cases analysed, 52.7% (n = 570) were male. The median age was 61 (range 18-85 years). The median BMI was 27.8 (range 20-52). The median procedure time is 28 (range 2-69 min). Routine follow-up was the clinical indication for 65% of colonoscopy procedures undertaken during the study period. Multivariate logistic regression, controlled for statistically insignificant confounders of age, type of bowel preparation agent, grade of the endoscopist, the indication for procedure and year of procedure, showed that being obese was significantly and independently associated with inadequate bowel preparation (OR 2.0, 95% CI (1.4-2.9) p < 0.001). Another significant factor was male (OR 1.6, 95% CI (1.2-2.1) p = 0.002).

CONCLUSION

This study shows that obese patients are more likely to have inadequate bowel preparation at colonoscopy. Given the increased complication rates and health care costs associated with repeating colonoscopies and the increased risk of colorectal cancer in obese patients, it may be worth tailoring a more extensive bowel preparation regimen to ensure adequate visualisation of the colonic mucosa on the first attempt.

Reduced gut microbiota diversity in patients with congenital generalized lipodystrophy

BACKGROUND

Previous studies suggest intestinal dysbiosis is associated with metabolic diseases. However, the causal relationship between them is not fully elucidated. Gut microbiota evaluation of patients with congenital generalized lipodystrophy (CGL), a disease characterized by the absence of subcutaneous adipose tissue, insulin resistance, and diabetes since the first years of life, could provide insights into these relationships.

METHODS

A cross-sectional study was conducted with patients with CGL (n = 17) and healthy individuals (n = 17). The gut microbiome study was performed by sequencing the 16S rRNA gene through High-Throughput Sequencing (BiomeHub Biotechnologies, Brazil).

RESULTS

The median age was 20.0 years old, and 64.7% were female. There was no difference between groups in pubertal stage, BMI, ethnicity, origin (rural or urban), delivery, breastfeeding, caloric intake, macronutrient, or fiber consumption. Lipodystrophic patients presented a lower alpha diversity (Richness index: 54.0 versus 67.5; p = 0.008). No differences were observed in the diversity parameters when analyzing the presence of diabetes, its complications, or the CGL subtype.

CONCLUSION

In this study, we demonstrate for the first time a reduced gut microbiota diversity in individuals with CGL. Dysbiosis was present despite dietary treatment and was also observed in young patients. Our findings allow us to speculate that the loss of intestinal microbiota diversity may be due to metabolic abnormalities present since the first years of life in CGL. Longitudinal studies are needed to confirm these findings, clarifying the possible causal link between dysbiosis and insulin resistance in humans.

Augmented leptin-induced trefoil factor 3 expression and epidermal growth factor receptor transactivation differentially influences neoplasia progression in the stomach and colorectum of dietary fat-induced obese mice

Obesity is a risk factor for gastrointestinal malignancies and tumors. However, which factors either protect or predispose the gastrointestinal organs to high-fat diet (HFD)-induced neoplasia remains unclear. Here, we demonstrate that HFD impacts the stomach to a greater extent as compared to the colorectum, resulting in leptin receptor (LepR) signaling-mediated neoplasia in the tissues. HFD activated leptin signaling, which in turn, accelerates the pathogenesis in the gastric mucosa more than that in the colorectum along with ectopic TFF3 expression. Moreover, in the stomach, higher levels of phosphorylated epidermal growth factor receptor (EGFR) in addition to the activation of STAT3 and Akt were observed as compared to the colorectum. The mice with LepR deletion in the gastrointestinal epithelium exhibited a suppressed induction of leptin, TFF3, and phosphorylated EGFR in the stomach, whereas the levels in the colorectum were insignificant. In co-transfected COS-7 cells with LepR and EGFR plasmid DNA, leptin transactivated EGFR to accelerate TFF3 induction along with activation of STAT3, ERK1/2, Akt, and PI3K p85/p55. Furthermore, TFF3 could bind to EGFR but did not transactivate LepR. Leptin-induced TFF3 induction was markedly suppressed by inhibitors of PI3K (LY294002) and EGFR (Erlotinib). Together, these results suggest a novel role of LepR-mediated signaling in transactivating EGFR that leads to TFF3 expression via the PI3K-Akt pathway. Therefore, this study sheds light on the identification of potentially new therapeutic targets for the treatment of pre-cancerous symptoms in stomach and colorectum.

The role of hypoleptinemia in the psychological and behavioral adaptation to starvation: implications for anorexia nervosa

This narrative review aims to pinpoint mental and behavioral effects of starvation, which may be triggered by hypoleptinemia and as such may be amenable to treatment with leptin receptor agonists. The reduced leptin secretion results from the continuous loss of fat mass, thus initiating a graded triggering of diverse starvation related adaptive functions. In light of leptin receptors located in several peripheral tissues and many brain regions adaptations may extend beyond those of the hypothalamus-pituitary-end organ-axes. We focus on gastrointestinal tract and reward system as relevant examples of peripheral and central effects of leptin. Despite its association with extreme obesity, congenital leptin deficiency with its many parallels to a state of starvation allows the elucidation of mental symptoms amenable to treatment with exogenous leptin in both ob/ob mice and humans with this autosomal recessive disorder. For starvation induced behavioral changes with an intact leptin signaling we particularly focus on rodent models for which proof of concept has been provided for the causative role of hypoleptinemia. For humans, we highlight the major cognitive, emotional and behavioral findings of the Minnesota Starvation Experiment to contrast them with results obtained upon a lesser degree of caloric restriction. Evidence for hypoleptinemia induced mental changes also stems from findings obtained in lipodystrophies. In light of the recently reported beneficial cognitive, emotional and behavioral effects of metreleptin-administration in anorexia nervosa we discuss potential implications for the treatment of this eating disorder. We postulate that leptin has profound psychopharmacological effects in the state of starvation.

Changes in the Leptin to Adiponectin Ratio Are Proportional to Weight Loss After Meal Replacement in Adults With Severe Obesity

Hypocaloric diets are known to induce changes in adipokine secretion, but the influence of a low energy liquid diet (LELD) on the leptin: adiponectin ratio (LAR), a measure of insulin resistance and cardiovascular risk, has not previously been investigated in patients with severe obesity. We conducted a prospective, single-center cohort study of adults with severe obesity (defined as body mass index (BMI) ≥40 kgm−2, or ≥35 kgm−2 with co-morbidities) who completed a 24-week milk-based LELD. We measured leptin, adiponectin and LAR at the start and on completion of the programme. Of 120 patients who started, 52 (43.3 %) completed the programme. Their mean age was 50.3 ± 11.2 (range 18–74) years, 29 (55.8 %) were female and 20 (38.5 %) had type 2 diabetes mellitus (T2DM). Weight decreased from 148.2 ± 39.6 to 125.4 ± 34.8 kg and BMI decreased from 52.4 ± 11.1 to 44.3 ± 9.8 kgm−2, respectively (all p &lt; 0.001). In patients with T2DM, HbA1c decreased from 60.0 ± 17.4 to 47.5 ± 15.5 mmol/mol (p &lt; 0.001). Leptin decreased (from 87.2 [48.6, 132.7] to 39.1 [21.0, 76.4] ng/ml) and adiponectin increased (from 5.6 [4.5, 7.5] to 7.1 [5.5, 8.5] μg/ml), with a reduction in LAR from 15 [8.4, 22.4] to 5.7 [3.0, 9.1] ng/μg (all p &lt; 0.001), indicating decreased insulin resistance. The percentage weight lost was associated with the percentage reduction in LAR (ß = 2.9 [1.7, 4.1], p &lt; 0.001) and this association was stronger in patients with T2DM. Patients with severe obesity who completed a milk-based LELD had a substantial reduction in LAR, consistent with decreased insulin resistance and cardiovascular risk, proportional to weight loss.

Abdominal obesity increases the risk of reflux esophagitis: a systematic review and meta-analysis

BACKGROUND AND OBJECTIVES

The association between abdominal obesity and reflux esophagitis (RE) has been extensively evaluated, but the current findings are mixed and more convincing epidemiological evidence urgently needs to be established. To thoroughly explore this relationship, we summarized the latest studies, performed an updated meta-analysis, and examined the dose-response relationship.

METHODS

We performed a systematic search of PubMed, Web of Science, and Embase up to 28 March 2021, using prespecified terms to identify studies investigating the association between abdominal obesity and RE. Odds ratios (ORs) with 95% confidence intervals (CIs), mean differences (MDs) or standardized mean differences (SMDs) with 95% CIs were taken as effect-size estimates.

RESULTS

Forty-two observational studies, including 11 cohort studies, were meta-analyzed. Overall, a statistically significant association was observed between abdominal obesity and RE, by both the pooled OR (adjusted OR = 1.51, 95% CI: 1.37-1.66, p < .001) and the pooled SMD (SMD = 0.36, 95% CI: 0.30-0.42, p < .001). Moreover, this significant relationship persisted with subgroup stratification. In subgroup analyses, we found that study design, abdominal obesity measurement, adjustment for covariates and sex were possible sources of between-study heterogeneity. For the dose-response analyses, the risk of RE increased with the degree of abdominal obesity, and the increasing trend accelerated when waist circumference (WC) reached 87.0 cm.

CONCLUSION

This meta-analysis indicated a significant association between abdominal obesity and RE, and the risk of RE increased with abdominal obesity especially when the WC was over 87.0 cm.

Peripheral versus central insulin and leptin resistance: Role in metabolic disorders, cognition, and neuropsychiatric diseases

Insulin and leptin are classically regarded as peptide hormones that play key roles in metabolism. In actuality, they serve several functions in both the periphery and central nervous system (CNS). Likewise, insulin and leptin resistance can occur both peripherally and centrally. Metabolic disorders such as diabetes and obesity share several key features including insulin and leptin resistance. While the peripheral effects of these disorders are well-known (i.e. cardiovascular disease, hypertension, stroke, dyslipidemia, etc.), the CNS complications of leptin and insulin resistance have come into sharper focus. Both preclinical and clinical findings have indicated that insulin and leptin resistance are associated with cognitive deficits and neuropsychiatric diseases such as depression. Importantly, these studies also suggest that these deficits in neuroplasticity can be reversed by restoration of insulin and leptin sensitivity. In view of these observations, this review will describe, in detail, the peripheral and central functions of insulin and leptin and explain the role of insulin and leptin resistance in various metabolic disorders, cognition, and neuropsychiatric diseases.

CD36 maintains the gastric mucosa and associates with gastric disease

The gastric epithelium is often exposed to injurious elements and failure of appropriate healing predisposes to ulcers, hemorrhage, and ultimately cancer. We examined the gastric function of CD36, a protein linked to disease and homeostasis. We used the tamoxifen model of gastric injury in mice null for Cd36 (Cd36-/-), with Cd36 deletion in parietal cells (PC-Cd36-/-) or in endothelial cells (EC-Cd36-/-). CD36 expresses on corpus ECs, on PC basolateral membranes, and in gastrin and ghrelin cells. Stomachs of Cd36-/- mice have altered gland organization and secretion, more fibronectin, and inflammation. Tissue respiration and mitochondrial efficiency are reduced. Phospholipids increased and triglycerides decreased. Mucosal repair after injury is impaired in Cd36-/- and EC-Cd36-/-, not in PC-Cd36-/- mice, and is due to defect of progenitor differentiation to PCs, not of progenitor proliferation or mature PC dysfunction. Relevance to humans is explored in the Vanderbilt BioVu using PrediXcan that links genetically-determined gene expression to clinical phenotypes, which associates low CD36 mRNA with gastritis, gastric ulcer, and gastro-intestinal hemorrhage. A CD36 variant predicted to disrupt an enhancer site associates (p < 10-17) to death from gastro-intestinal hemorrhage in the UK Biobank. The findings support role of CD36 in gastric tissue repair, and its deletion associated with chronic diseases that can predispose to malignancy.

Triacylglycerol rich in docosahexaenoic acid regulated appetite via the mediation of leptin and intestinal epithelial functions in high-fat, high-sugar diet-fed mice

High-fat, high-sugar diet (HFHS) induced leptin resistance and intestinal epithelial dysfunction is implicated in hyperphagia and metabolic disorders. Numerous studies have demonstrated the efficacy of dietary interventions for reducing appetite. This study aims to investigate whether triacylglycerol rich in DHA (DHA-TG) could regulate appetite in mice fed with a HFHS diet and the mechanism by which it achieves that. DHA-TG could reduce food intake and regulate neuropeptides (POMC, AgRP, and NPY) expression in HFHS diet-fed mice. Hypothalamic transcriptome analysis reveals that these effects might be attributed to the role of DHA-TG in modulating hormone secretion and digestive system process. According to ELISA and RT-qPCR analysis, DHA-TG ameliorated leptin secretion and attenuated central leptin resistance induced by HFHS diet feeding. Besides, DHA-TG prevented the damage of intestinal epithelial barrier in nutritive obese mice by improving leptin sensitivity. Based on jejunal transcriptome analysis, DHA-TG also protected intestinal endocrine function, especially the secretion of another anorectic hormone, cholecystokinin (CCK), in HFHS diet-fed mice. Furthermore, DHA-TG was ineffective in repressing appetite, and improving gut leakage in leptin-deficient mice (ob/ob mice). In conclusion, DHA-TG has a potential to regulate appetite with the action of leptin, and intestinal epithelial functions in HFHS diet-fed mice.

Leptin receptor-deficient (knockout) zebrafish: Effects on nutrient acquisition

In mammals, knockout of LEPR results in a hyperphagic, morbid obese, and diabetic phenotype, which supports that leptin plays an important role in the control of appetite and energy metabolism, and that its receptor, LEPR, mediates these effects. To date, little is known about the role(s) of lepr in teleost physiology. We investigated a zebrafish (Danio rerio) homozygous lepr knockout (lepr^-/-) line generated by CRISPR/Cas9 in comparison to its wt counterpart with respect to nutrient acquisition, energy allocation, and metabolism. The metabolic characterization included oxygen consumption rate and morphometric parameters (yolk sac area, standard length, wet weight, and condition factor) as proxies for use and allocation of energy in developing (embryos, larvae, and juveniles) zebrafish and showed no particular differences between the two lines, in agreement with previous studies. One exception was found in oxygen consumption at 72 hpf, when zebrafish switch from embryonic to early larval stages and food-seeking behavior could be observed. In this case, the metabolic rate was significantly lower in lepr^-/- than in wt. Both phenotypes showed similar responses, with respect to metabolic rate, to acute alterations (22 and 34 °C) in water temperature (measured in terms of Q₁₀ and activation energy) compared to the standard (28 °C) rearing conditions. To assess lepr involvement in signaling the processing and handling of incoming nutrients when an exogenous meal is digested and absorbed, we conducted an in vivo analysis in lepr^-/- and wt early (8 days post-fertilization) zebrafish larvae. The larvae were administered a bolus of protein hydrolysate (0%, 1%, 5%, and 15% lactalbumin) directly into the digestive tract lumen, and changes in the mRNA expression profile before and after (1 and 3 h) administration were quantified. The analysis showed transcriptional differences in the expressions of genes involved in the control of appetite and energy metabolism (cart, npy, agrp, and mc4r), sensing (casr, t1r1, t1r3, t1r2-1, t1r2-2, pept1a, and pept1b), and digestion (cck, pyy, try, ct, and amy), with more pronounced effects observed in the orexigenic than in the anorexigenic pathways, suggesting a role of lepr in their regulations. Differences in the mRNA levels of these genes in lepr^-/-vs. wt larvae were also observed. Altogether, our analyses suggest an influence of lepr on physiological processes involved in nutrient acquisition, mainly control of food intake and digestion, during early development, whereas metabolism, energy allocation, and growth seem to be only slightly influenced.

Leptin-resistant Zucker rats with trinitrobenzene sulfonic acid colitis present a reduced inflammatory response but enhanced epithelial damage

The role of leptin in the development of intestinal inflammation remains controversial, since proinflammatory and anti-inflammatory effects have been described. This study describes the effect of the absence of leptin signaling in intestinal inflammation. Experimental colitis was induced by intrarectal administration of trinitrobenzene sulfonic acid (TNBS) to lean and obese Zucker rats (n = 10). Effects on inflammation and mucosal barrier were studied. Bacterial translocation and LPS concentration were evaluated together with colonic permeability to 4-kDa FITC-dextran. Obese Zucker rats showed a lower intestinal myeloperoxidase and alkaline phosphatase activity, reduced alkaline phosphatase sensitivity to levamisole, and diminished colonic expression of Nos2, Tnf, and Il6, indicating attenuated intestinal inflammation, associated with attenuated STAT3, AKT, and ERK signaling in the colonic tissue. S100a8 and Cxcl1 mRNA levels were maintained, suggesting that in the absence of leptin signaling neutrophil activation rather than infiltration is hampered. Despite the lower inflammatory response, leptin resistance enhanced intestinal permeability, reflecting an increased epithelial damage. This was shown by augmented LPS presence in the portal vein of colitic obese Zucker rats, associated with induction of tissue nonspecific alkaline phosphatase, LPS-binding protein, and CD14 hepatic expression (involved in LPS handling). This was linked to decreased ZO-1 immunoreactivity in tight junctions and lower occludin expression. Our results indicate that obese Zucker rats present an attenuated inflammatory response to TNBS, but increased intestinal epithelial damage allowing the passage of bacterial antigens.NEW & NOTEWORTHY Obese Zucker rats, which are resistant to leptin, exhibit a diminished inflammatory response in the trinitrobenzenesulfonic acid (TNBS) model of colitis, suggesting leptin role is proinflammatory. At the same time, obese Zucker rats present a debilitated intestinal barrier function, with increased translocation of LPS. Zucker rats present a dual response in the TNBS model of rat colitis.

Human Milk Hormone Intake in the First Month of Life and Physical Growth Outcomes in Preterm Infants

CONTEXT

Human milk contains hormones that regulate metabolism. Extrauterine growth restriction remains common among preterm infants, but the effect of ingesting milk hormones on preterm infant growth is poorly understood.

OBJECTIVE

To quantify associations of longitudinal exposure to leptin, adiponectin, and insulin in milk with physical growth of preterm infants.

DESIGN/METHODS

In 50 preterm neonates (median gestational age 29.4 weeks), we sampled maternal milk on day-of-life 7, 14, 21, and 28 and measured hormone levels in whole milk by ELISA. Milk leptin levels were available for a subset of 18 infants. We calculated milk hormone doses by multiplying the hormone level by the milk volume ingested on each day and estimated the area under the curve (AUC) to reflect longitudinal exposure. We analyzed associations of milk hormone exposure with growth outcomes in generalized estimated equations.

MAIN OUTCOME MEASURES

Weight gain velocity and z-scores in weight, length, head circumference, and body mass index at 36 weeks' postmenstrual age (PMA).

RESULTS

Higher leptin intake was associated with greater weight gain (2.17g/kg/day [95% CI, 1.31, 3.02]) and weight z-score at 36 weeks' PMA (0.30 [0.08, 0.53] higher z-score per tertile). Higher adiponectin intake was associated with greater length z-score (0.41 [0.13, 0.69]), however, this association was nullified after adjustment of protein and calorie intake. Higher adiponectin was associated with smaller head circumference z-score (-0.36 [-0.64, -0.07]). Insulin was not associated with growth outcomes.

CONCLUSIONS

Milk leptin and adiponectin exposures may affect growth of preterm infants. The long-term effects of milk hormones warrant further investigation.

Protective effects of curcumin against rat intestinal inflammation‑related motility disorders

Intestinal inflammation frequently occurs alongside dysmotility, which is characterized by altered myosin light chain phosphorylation levels. Curcumin, an active component from the ginger family, is reported to confer anti‑inflammatory effects. However, the effects of curcumin on both diarrhea and constipation associated inflammation remains to be elucidated. The present study was designed to investigate the effects of curcumin on diarrhea and constipation and to determine the related mechanisms. Sprague‑Dawley rats were used to establish diarrhea and constipation models via intracolonic acetic acid (4%) instillation or cold water gavage for 2 weeks, respectively. Blood samples were collected to measure the serum levels of the cytokines TNF‑α and IL‑1β using ELISA kits. Western blotting was performed to measure NF‑κB, RhoA, Rho‑related kinase 2, phosphorylated MLC₂₀, phosphorylated myosin phosphorylated target subunit 1, 130k Da‑MLC kinase (MLCK), c‑kit tyrosine kinase protein expression, and reverse transcription‑quantitative PCR was conducted to measure MLCK expression levels. The results indicated that curcumin reversed the elevations in the pro‑inflammatory cytokines IL‑1β and TNF‑α by inhibiting the NF‑κB pathway in rats with diarrhea and constipation. The results also indicated that myosin light chain (MLC) phosphorylation in intestinal smooth muscle was positively and negatively associated with the motility of inflammation‑related diarrhea and constipation in rats, respectively. Curcumin significantly reversed the increased MLC phosphorylation in the jejunum of the rats with diarrhea, significantly enhanced the reductions in inflammatory mediators, including TNF‑α and IL‑1β, of rats with constipation and significantly ameliorated the related hyper‑motility and hypo‑motility in rats with both diarrhea and constipation. In conclusion, the potential roles of the MLC kinase, c‑kit tyrosine and Rho A/Rho‑associated kinase 2 pathways, which are involved in curcumin‑induced amelioration of inflammation‑related diarrhea and constipation, were explored in the present study. Results from the present study suggested that curcumin has potential therapeutic value for treating intestinal inflammation and inflammation‑related motility disorders.

Understanding the appetite modulation pathways: The role of the FFA1 and FFA4 receptors

Pharmaconutrition is an area of current interest, especially concerning the advances in the pharmacology of nutrient-sensing receptors, as have been accomplished in the last 20 years. The family of free fatty acid (FFA) receptors is composed of four members, sequentially named as FFA1 to FFA4, which are activated by the short to long-chain fatty acids. The affinity of the FFA1 and FFA4 receptors for the omega-3 polyunsaturated fatty acids prompted pre-clinical and clinical investigations regarding their involvement in metabolic diseases. The main studies have been focused on the receptors' expression analyses, the featuring of knockout mice, and the assessment of selective synthetic ligands. These clearly have indicated a relevant role for FFA1 and FFA4 in the peripheral and central circuits for the regulation of energetic metabolism. This review article aimed to discuss the relevance of the FFA1 and FFA4 receptors in appetite-related complications, mainly related to obesity, cancer cachexia, and anorexia in the elderly, emphasizing whether their pharmacological modulation might be useful for the management of these disorders.

Alterations in Small Intestine and Liver Morphology, Immunolocalization of Leptin, Ghrelin and Nesfatin-1 as Well as Immunoexpression of Tight Junction Proteins in Intestinal Mucosa after Gastrectomy in Rat Model

The stomach is responsible for the processing of nutrients as well as for the secretion of various hormones which are involved in many activities throughout the gastrointestinal tract. Experimental adult male Wistar rats (n = 6) underwent a modified gastrectomy, while control rats (n = 6) were sham-operated. After six weeks, changes in small intestine (including histomorphometrical parameters of the enteric nervous plexuses) and liver morphology, immunolocalization of leptin, ghrelin and nesfatin-1 as well as proteins forming adherens and tight junctions (E-cadherin, zonula occludens-1, occludin, marvelD3) in intestinal mucosa were evaluated. A number of effects on small intestine morphology, enteric nervous system ganglia, hormones and proteins expression were found, showing intestinal enteroplasticity and neuroplasticity associated with changes in gastrointestinal tract condition. The functional changes in intestinal mucosa and the enteric nervous system could be responsible for the altered intestinal barrier and hormonal responses following gastrectomy. The results suggest that more complicated regulatory mechanisms than that of compensatory mucosal hypertrophy alone are involved.

Unraveling the Role of Leptin in Liver Function and Its Relationship with Liver Diseases

Since its discovery twenty-five years ago, the fat-derived hormone leptin has provided a revolutionary framework for studying the physiological role of adipose tissue as an endocrine organ. Leptin exerts pleiotropic effects on many metabolic pathways and is tightly connected with the liver, the major player in systemic metabolism. As a consequence, understanding the metabolic and hormonal interplay between the liver and adipose tissue could provide us with new therapeutic targets for some chronic liver diseases, an increasing problem worldwide. In this review, we assess relevant literature regarding the main metabolic effects of leptin on the liver, by direct regulation or through the central nervous system (CNS). We draw special attention to the contribution of leptin to the non-alcoholic fatty liver disease (NAFLD) pathogenesis and its progression to more advanced stages of the disease as non-alcoholic steatohepatitis (NASH). Likewise, we describe the contribution of leptin to the liver regeneration process after partial hepatectomy, the mainstay of treatment for certain hepatic malignant tumors.

Stratified layer analysis reveals intrinsic leptin stimulates cryptal mesenchymal cells for controlling mucosal inflammation

Mesenchymal cells in the crypt play indispensable roles in the maintenance of intestinal epithelial homeostasis through their contribution to the preservation of stem cells. However, the acquisition properties of the production of stem cell niche factors by the mesenchymal cells have not been well elucidated, due to technical limitations regarding the isolation and subsequent molecular and cellular analyses of cryptal mesenchymal cells. To evaluate the function of mesenchymal cells located at the large intestinal crypt, we established a novel method through which cells are harvested according to the histologic layers of mouse colon, and we compared cellular properties between microenvironmental niches, the luminal mucosa and crypts. The gene expression pattern in the cryptal mesenchymal cells showed that receptors of the hormone/cytokine leptin were highly expressed, and we found a decrease in Wnt2b expression under conditions of leptin receptor deficiency, which also induced a delay in cryptal epithelial proliferation. Our novel stratified layer isolation strategies thus revealed new microenvironmental characteristics of colonic mesenchymal cells, including the intrinsic involvement of leptin in the control of mucosal homeostasis.

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

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

Short-term metreleptin treatment of patients with anorexia nervosa: rapid on-set of beneficial cognitive, emotional, and behavioral effects

To examine the hypothesis that normalization of low circulating leptin levels in patients with anorexia nervosa ameliorates hyperactivity, three seriously ill females with hyperactivity were treated off-label with metreleptin (recombinant human leptin) for up to 14 days. Drive for activity, repetitive thoughts of food, inner restlessness, and weight phobia decreased in two patients. Surprisingly, depression improved rapidly in all patients. No serious adverse events occurred. Due to obvious limitations of uncontrolled case series, placebo-controlled clinical trials are mandatory to confirm the observed rapid onset of beneficial effects. Our findings suggest an important role of hypoleptinemia in the mental and behavioral phenotype of anorexia nervosa.

Leptin levels in SARS-CoV-2 infection related respiratory failure: A cross-sectional study and a pathophysiological framework on the role of fat tissue

Obesity is a risk factor for SARS-CoV-2 infected patients to develop respiratory failure. Leptin produced in visceral fat might play a role in the deterioration to mechanical ventilation. A cross sectional study was performed. The mean BMI was 31 kg/m² (range 24.8–48.4) for the 31 SARS-CoV-2 ventilated patients and 26 kg/m² (range 22.4–33.5) for 8 critically ill non-infected control patients. SARS-CoV-2 infected patients with a similar BMI as control patients appear to have significantly higher levels of serum leptin. The mean leptin level was 21.2 (6.0–85.2) vs 5.6 (2.4–8.2) ug/L for SARS-CoV-2 and controls respectively (p = 0.0007). With these findings we describe a clinical and biological framework that may explain these clinical observations. The ACE2 utilization by the virus leads to local pulmonary inflammation due to ACE2-ATII disbalance. This might be enhanced by an increase in leptin production induced by SARS-CoV-2 infection of visceral fat. Leptin receptors in the lungs are now more activated to enhance local pulmonary inflammation. This adds to the pre-existent chronic inflammation in obese patients. Visceral fat, lung tissue and leptin production play an interconnecting role. This insight can lead the way to further research and treatment.

Obesity and esophageal cancer: GERD, Barrett´s esophagus, and molecular carcinogenic pathways

INTRODUCTION

Increases in the rates of esophageal adenocarcinoma (EAC) have paralleled rises in the prevalence of overweight and obesity. Despite not being fully understood, obesity-related EAC seems to have different carcinogenic pathways.

AREAS COVERED

This comprehensive review will thoroughly evaluate the current literature, describing the underlying mechanisms that help understanding the strong association between obesity and esophageal cancer.

EXPERT COMMENTARY

The risk of esophageal cancer among obese individuals could be partially explained by several factors: high prevalence of GERD; linear association between central adiposity and Barrett´s esophagus development; low levels of adiponectin and high levels of leptin that alter cell proliferation processes; insulin-resistant state that creates a tumorigenesis environment; and changes in the esophageal microbiota due to unhealthy dietary habits that promote carcinogenesis. In addition, a large proportion of obese patients are undergoing sleeve gastrectomy which can worsen GERD or cause de novo reflux, esophagitis, and Barrett´s metaplasia.

Can adiponectin have an additional effect on the regulation of food intake by inducing gastric motor changes?

The regulation of food intake is a complex mechanism, and the hypothalamus is the main central structure implicated. In particular, the arcuate nucleus appears to be the most critical area in the integration of multiple peripheral signals. Among these signals, those originating from the white adipose tissue and the gastrointestinal tract are known to be involved in the regulation of food intake. The present paper focuses on adiponectin, an adipokine secreted by white adipose tissue, which is reported to have a role in the control of feeding by acting centrally. The recent observation that adiponectin is also able to influence gastric motility raises the question of whether this action represents an additional peripheral mechanism that concurs with the central effects of the hormone on food intake. This possibility, which represents an emerging aspect correlating the central and peripheral effects of adiponectin in the hunger-satiety cycle, is discussed in the present paper.

Features of the course of gallstone disease in patients with non-alcoholic fatty liver disease

Aim.To update information about comorbidity of non-alcoholic fatty liver disease (NAFLD) and gallstones disease (GD), evaluation of clinical and laboratory data, including insulin, leptin and adiponectin in individuals with NAFLD in combination with GD. Materials and methods.According to the design, we conducted an open comparative study of 169 patients with NAFLD. The following comparison groups were formed: group 1 (n=95) patients with NAFLD without GD, group 2 (n=35) patients with NAFLD and GD and group 3 (n=39) patients with NAFLD, GD and previous cholecystectomy. Results.A high prevalence of coronary heart disease was found in the group of patients with GD and cholecystectomy (2=6.198,p0.05); positive, statistically significant correlation relationships of cholelithiasis, cholecystectomy with ischemic heart disease (rs=0.172,p0.05 andrs=0.241,p0.05, respectively). There was a statistically significant decrease in total bilirubin and total protein in patients of group 3 (H=7.376,p0.03 and H=6.345,p0.04). The level of leptin is statistically significantly higher and positively interrelated with cholecystectomy (H=5.812,p0.05,rs=0.313,p0.05). Conclusion.Patients with NAFLD, GD and previous cholecystectomy have a high prevalence of coronary heart disease; the phenomenon of insulin and leptin resistance, high level of adiponectin were revealed in patients with NAFLD and gallstones; hyperleptinemia was observed among patients with NAFLD, GD after cholecystectomy.

Functional, Diagnostic and Therapeutic Aspects of Gastrointestinal Hormones

Gastrointestinal (GI) hormones are essential to many physiologic functions in our body. They have many GI and extra-GI functions. Some of the functions of these hormones, which have GI and extra-GI sources, are still unknown. Specific GI hormones can affect the brain to control food intake, while others can proliferate normal and neoplastic tissue when their receptors are expressed in certain neoplasms. GI hormones also have many diagnostic and therapeutic roles. Physiologic and pathophysiologic aspects as well as the diagnostic and therapeutic values of GI hormones are elaborated in this review.

Avian Expression Patterns and Genomic Mapping Implicate Leptin in Digestion and TNF in Immunity, Suggesting That Their Interacting Adipokine Role Has Been Acquired Only in Mammals

In mammals, leptin and tumor-necrosis factor (TNF) are prominent interacting adipokines mediating appetite control and insulin sensitivity. While TNF pleiotropically functions in immune defense and cell survival, leptin is largely confined to signaling energy stores in adipocytes. Knowledge about the function of avian leptin and TNF is limited and they are absent or lowly expressed in adipose, respectively. Employing radiation-hybrid mapping and FISH-TSA, we mapped TNF and its syntenic genes to chicken chromosome 16 within the major histocompatibility complex (MHC) region. This mapping position suggests that avian TNF has a role in regulating immune response. To test its possible interaction with leptin within the immune system and beyond, we compared the transcription patterns of TNF, leptin and their cognate receptors obtained by meta-analysis of GenBank RNA-seq data. While expression of leptin and its receptor (LEPR) were detected in the brain and digestive tract, TNF and its receptor mRNAs were primarily found in viral-infected and LPS-treated leukocytes. We confirmed leptin expression in the duodenum by immunohistochemistry staining. Altogether, we suggest that whereas leptin and TNF interact as adipokines in mammals, in birds, they have distinct roles. Thus, the interaction between leptin and TNF may be unique to mammals.

Adiponectin Decreases Gastric Smooth Muscle Cell Excitability in Mice

Some adipokines known to regulate food intake at a central level can also affect gastrointestinal motor responses. These are recognized to be peripheral signals able to influence feeding behavior as well. In this view, it has been recently observed that adiponectin (ADPN), which seems to have a role in sending satiety signals at the central nervous system level, actually affects the mechanical responses in gastric strips from mice. However, at present, there are no data in the literature about the electrophysiological effects of ADPN on gastric smooth muscle. To this aim, we achieved experiments on smooth muscle cells (SMCs) of gastric fundus to find out a possible action on SMC excitability and on membrane phenomena leading to the mechanical response. Experiments were made inserting a microelectrode in a single cell of a muscle strip of the gastric fundus excised from adult female mice. We found that ADPN was able to hyperpolarize the resting membrane potential, to enhance the delayed rectifier K⁺ currents and to reduce the voltage-dependent Ca²⁺ currents. Our overall results suggest an inhibitory action of ADPN on gastric SMC excitation-contraction coupling. In conclusion, the depressant action of ADPN on the gastric SMC excitability, here reported for the first time, together with its well-known involvement in metabolism, might lead us to consider a possible contribution of ADPN also as a peripheral signal in the hunger-satiety cycle and thus in feeding behavior.

Adipocytes-released Peptides Involved in the Control of Gastrointestinal Motility

The present review focuses on adipocytes-released peptides known to be involved in the control of gastrointestinal motility, acting both centrally and peripherally. Thus, four peptides have been taken into account: leptin, adiponectin, nesfatin-1, and apelin. The discussion of the related physiological or pathophysiological roles, based on the most recent findings, is intended to underlie the close interactions among adipose tissue, central nervous system, and gastrointestinal tract. The better understanding of this complex network, as gastrointestinal motor responses represent peripheral signals involved in the regulation of food intake through the gut-brain axis, may also furnish a cue for the development of either novel therapeutic approaches in the treatment of obesity and eating disorders or potential diagnostic tools.

Changes in pre- and postoperative serum leptin concentrations in dogs with gallbladder mucocele and cholelithiasis

Background

Leptin has been shown to have various physiological and pathological roles in the canine gallbladder. In this study, we performed pre- and postoperative short-term follow-up analyses to confirm changes in serum leptin levels before and after cholecystectomy due to gallbladder mucocele (GBM) or cholelithiasis in dogs.

Results

Twenty-six cholecystectomized dogs (GBM: n = 14; cholelithiasis: n = 12) for prophylactic or clinical symptom relief were enrolled in the present study. Dogs were subgrouped according to clinical symptoms and prognosis after surgery as follows: 1) asymptomatic group (n = 13), 2) recovery group (n = 8), and 3) death group (n = 5). Liver enzymes, total bilirubin, lipid profiles, and leptin concentrations were determined from sera on the pre-operative day and at 1, 3, and 7 days postoperation. Serum leptin concentrations were gradually but significantly decreased in the asymptomatic group (p = 0.008, 0.004, and 0.004 on days 1, 3, and 7, respectively, compared with that before surgery) and the recovery group (p = 0.048 and 0.048 on days 3 and 7, respectively, compared with that before surgery). However, in the death group, leptin concentrations did not differ significantly over time (p = 0.564). Additionally, serum leptin levels in the recovery group (p = 0.006) and death group (p = 0.021) were significantly higher than those in the asymptomatic group. Liver enzymes and total bilirubin (T-Bil) were significantly decreased only in the recovery group, particularly on day 7. In the asymptomatic group, liver enzymes and T-Bil were not changed significantly over time, and in the death group, only T-Bil was significantly decreased on day 7. Total cholesterol and triglyceride levels were not significantly decreased over time in all groups.

Conclusions

These results indicate that leptin is a potential biomarker reflecting the severity and prognosis of GBM and cholelithiasis both before and after cholecystectomy in dogs.

Duodenal adipose tissue is associated with obesity in baboons (Papio sp): a novel site of ectopic fat deposition in non-human primates

AIMS

Ectopic fat is a recognized contributor to insulin resistance and metabolic dysfunction, while the role of fat deposition inside intestinal wall tissue remains understudied. We undertook this study to directly quantify and localize intramural fat deposition in duodenal tissue and determine its association with adiposity.

METHODS

Duodenal tissues were collected from aged (21.2 ± 1.3 years, 19.5 ± 3.1 kg, n = 39) female baboons (Papio sp.). Fasted blood was collected for metabolic profiling and abdominal circumference (AC) measurements were taken. Primary tissue samples were collected at the major duodenal papilla at necropsy: one full cross section was processed for hematoxylin and eosin staining and evaluated; a second full cross section was processed for direct chemical lipid analysis on which percentage duodenal fat content was calculated.

RESULTS

Duodenal fat content obtained by direct tissue quantification showed considerable variability (11.95 ± 6.93%) and was correlated with AC (r = 0.60, p < 0.001), weight (r = 0.38, p = 0.02), leptin (r = 0.63, p < 0.001), adiponectin (r = - 0.32, p < 0.05), and triglyceride (r = 0.41, p = 0.01). The relationship between duodenal fat content and leptin remained after adjusting for body weight and abdominal circumference. Intramural adipocytes were found in duodenal sections from all animals and were localized to the submucosa. Consistent with the variation in tissue fat content, the submucosal adipocytes were non-uniformly distributed in clusters of varying size. Duodenal adipocytes were larger in obese vs. lean animals (106.9 vs. 66.7 µm², p = 0.02).

CONCLUSIONS

Fat accumulation inside the duodenal wall is strongly associated with adiposity and adiposity related circulating biomarkers in baboons. Duodenal tissue fat represents a novel and potentially metabolically active site of ectopic fat deposition.

GASTROINTESTINAL MOTILITY DISORDERS IN OBESITY

The gastrointestinal (GI) motility, which is important for the digestion and absorption, may be altered in obesity. The aim of this review is to present the GI motility changes occurring in obesity, as well as their underlying mechanisms. We have conducted a systematic review of the published literature concerning GI motility and obesity and have described recent published data on the changes throughout the entire GI tract. Most recent discoveries include evidence supporting the increase of gastroesophageal reflux disease in obesity and inhibition of gastric motility. Intestinal transit of the distal small bowel generally slows down, ensuring enough time for digestion and absorption. Constipation is more frequent in obese patients than in those with a normal weight. The gut-brain axis plays an important role in the pathophysiology of GI motility disorders in obesity. This bidirectional communication is achieved by way of neurons, hormones, metabolites derived from intestinal microbiota and cytokines. The molecular mechanisms of GI motility changes in obesity are complex. Current data offer a starting point for further research needed to clarify the association of obesity with GI motility disorders.

Adiponectin affects the mechanical responses in strips from the mouse gastric fundus

AIM

To investigate whether the adipocytes derived hormone adiponectin (ADPN) affects the mechanical responses in strips from the mouse gastric fundus.

METHODS

For functional experiments, gastric strips from the fundal region were cut in the direction of the longitudinal muscle layer and placed in organ baths containing Krebs-Henseleit solution. Mechanical responses were recorded via force-displacement transducers, which were coupled to a polygraph for continuous recording of isometric tension. Electrical field stimulation (EFS) was applied via two platinum wire rings through which the preparation was threaded. The effects of ADPN were investigated on the neurally-induced contractile and relaxant responses elicited by EFS. The expression of ADPN receptors, Adipo-R1 and Adipo-R2, was also evaluated by touchdown-PCR analysis.

RESULTS

In the functional experiments, EFS (4-16 Hz) elicited tetrodotoxin (TTX)-sensitive contractile responses. Addition of ADPN to the bath medium caused a reduction in amplitude of the neurally-induced contractile responses (P < 0.05). The effects of ADPN were no longer observed in the presence of the nitric oxide (NO) synthesis inhibitor L-N^G-nitro arginine (L-NNA) (P > 0.05). The direct smooth muscle response to methacholine was not influenced by ADPN (P > 0.05). In carbachol precontracted strips and in the presence of guanethidine, EFS induced relaxant responses. Addition of ADPN to the bath medium, other than causing a slight and progressive decay of the basal tension, increased the amplitude of the neurally-induced relaxant responses (P < 0.05). Touchdown-PCR analysis revealed the expression of both Adipo-R1 and Adipo-R2 in the gastric fundus.

CONCLUSION

The results indicate for the first time that ADPN is able to influence the mechanical responses in strips from the mouse gastric fundus.

Presence and distribution of leptin and its receptor in the gut of adult zebrafish in response to feeding and fasting

Leptin is an anorectic hormone secreted mainly by peripheral adipocytes but also by other central and peripheral tissues. It acts by means of a receptor called OB-R, influencing not only appetite and body mass but being also involved in many fields like endocrinology, metabolism and reproduction. Immunohistochemistry and qRT-PCR techniques were, respectively, used to demonstrate the presence of leptin and its receptor in the gut of adult zebrafish and to evaluate the leptin gene expression response to feeding and fasting. Immunoreactivity for the antibodies utilized was demonstrated in feeding but not in fasting fish, and the gene expression analysis corroborates the data obtained by immunohistochemistry. Therefore, all the obtained results support the hypothesis of the role of this hormone in food regulation in zebrafish.

Leptin Aggravates Reflux Esophagitis by Increasing Tissue Levels of Macrophage Migration Inhibitory Factor in Rats

Leptin, produced primarily by the adipose tissue, acts as a pro-inflammatory modulator, thereby contributing to the development of obesity-related disease. Although high levels of leptin in the obese are closely related to gastroesophageal reflux disease, the mechanism by which leptin influences esophageal inflammation remains unknown. Macrophage migration inhibitory factor (MIF) is produced by immune cells, such as T lymphocytes and macrophages, and MIF is known to induce the production of tumor necrosis factor α (TNF-α), interleukin 1β (IL-1β) and interleukin 6 (IL-6). We therefore investigated the mechanism whereby leptin aggravates reflux esophagitis, by focusing on esophageal tissue levels of MIF and CD3+ T lymphocytes, both of which are crucial for the reflux-induced epithelial damage. Esophageal inflammation was surgically induced in male Wistar rats by ligating the forestomach and narrowing the duodenum to facilitate gastroesophageal reflux, followed by administration of leptin or vehicle with an osmotic pump system for 1 week. We demonstrated that the administration of leptin exacerbated the reflux esophagitis with the apparent infiltration of CD3+ T lymphocytes and caused the significant increase in the esophageal tissue levels of MIF. Moreover, the leptin caused increases in the esophageal tissue levels of TNF-α, IL-1β and IL-6, downstream targets of MIF. Importantly, the increases in these pro-inflammatory cytokines were accompanied by increased protein levels of phospho-STAT3 and phospho-AKT, pivotal molecules of leptin signaling pathways. In conclusion, through enhancing the MIF-induced inflammatory signaling, leptin could contribute to the development of gastroesophageal reflux disease.

Gastric bacterial Flora in patients Harbouring Helicobacter pylori with or without chronic dyspepsia: analysis with matrix-assisted laser desorption ionization time-of-flight mass spectroscopy

Background

The gastric microbiota has recently been implicated in the causation of organic/structural gastroduodenal diseases (gastric and duodenal ulcers, gastric cancer) in patients with Helicobacter pylori (H. pylori) infection. We aimed to ascertain, in patients harbouring H. pylori, the role of the gastric microbiota in the causation of symptoms (chronic dyspepsia) in the absence of organic disease.

Methods

Seventy-four gastric biopsy samples obtained at endoscopy from patients with (n = 21) or without (n = 53) chronic dyspepsia, and that tested positive by the bedside rapid urease test for H. pylori infection, were cultured for detection of H. pylori and non-H. pylori organisms. The cultured organisms were identified by matrix-assisted laser desorption ionization time-of-flight mass spectroscopy (MALDI-TOF MS).

Results

A total of 106 non-H. pylori isolates were obtained from 74 patients’ samples. This included 33 isolates (median 2, range 1–2 per patient) from dyspeptic and 73 (median 2, range 1–2 per patient) from non-dyspeptic patients. These were identified from the Bruker Biotyper 2 database as Staphylococcus spp., Streptococcus spp., Lactobacillus spp., Micrococcus spp., Enterococcus spp., Pseudomonas spp., Escherichia spp., Klebsiella spp. and Bacillus spp., Staphylococcus and Lactobacillus were identified significantly more commonly in dyspeptics and Streptococcus, Pseudomonas, Escherichia coli and Klebsiella pneumoniae in non-dyspeptics. All identified organisms belonged to the phyla Firmicutes and Proteobacteria.

Conclusions

There is a qualitative difference in the gastric microbial spectrum between patients harbouring H. pylori with and without chronic dyspepsia. Whether these organisms have an independent role in the development or prevention of dyspepsia or act in concurrence with H. pylori needs study.

The relationship of human milk leptin and macronutrients with gastric emptying in term breastfed infants

BackgroundInfants breastfed on demand exhibit a variety of feeding patterns and self-regulate their nutrient intake, but factors influencing their gastric emptying (GE) are poorly understood. Despite research into appetite regulation properties of leptin, there is limited information about relationships between human milk leptin and infant GE.MethodsGastric volumes were calculated from ultrasound scans of infants' stomachs (n=20) taken before and after breastfeeding, and then every 12.5 min (median; range: 3-45 min) until the next feed. Skim milk leptin and macronutrient concentrations were measured and doses were calculated.ResultsThe leptin concentration was (mean±SD) 0.51±0.16 ng/ml; the leptin dose was 45.5±20.5 ng per feed. No relationships between both concentration and dose of leptin and time between the feeds (P=0.57; P=1, respectively) or residual stomach volumes before the subsequent feed (P=0.20; P=0.050) were found. Post-feed stomach volumes (GE rate) were not associated with leptin concentration (P=0.77) or dose (P=0.85).ConclusionGE in term breastfed infants was not associated with either skim milk leptin concentration or dose. Further investigation with inclusion of whole-milk leptin and other hormones that affect gastrointestinal activity is warranted.

Leptin-like immunoreactivity in the central nervous system, digestive organs, and gonads of the giant freshwater prawn, Macrobrachium rosenbergii

Leptin, a highly conserved adipocyte-derived hormone, plays important roles in a variety of physiological processes, including the control of fat storage and metabolic status which are linked to food intake, energy homeostasis, and reproduction in all vertebrates. In the present study, we hypothesize that leptin is also present in various organs of the fresh water prawns, Macrobrachium rosenbergii. The existence and distribution of a leptin-like peptide in prawn tissues were verified by using Western blotting (WB) and immunohistochemical detection (ID) using primary antibody against human leptin. With WB, a leptin-like peptide, having a molecular weight of 15kDa, was detected in the brain, thoracic ganglia, abdominal ganglia, parts of the gastro-intestinal tract, hepatopancreas, adipocytes and gonads. By ID, leptin immunoreactivity (leptin-ir) was detected in the brain, thoracic ganglia and intersegmental commissural nerve fibers of abdominal ganglia. In the gastrointestinal tract, there was intense leptin-ir in the apical part of the epithelial cells of the cardiac and pyloric parts of the stomach. In the midgut and hindgut, the leptin-ir was detected in epithelial cells and basal cells located near the basal lamina of the epithelium. In addition, there was leptin-ir in the Restzellen cells in the hepatopancreas which produce digestive enzymes. In the ovary, the strong intensity of a leptin-ir was detected in the cytoplasm of middle to late stage oocytes, whereas no positive staining was detected in follicular cells. An intense leptin-ir was detected in spermatocytes and sustentacular cells in the seminiferous tubules in the testes of small and orange claw males. Taken together, the detection of the leptin-ir in several organs implicates the existence of a leptin-like peptide in various organs of the freshwater prawn; and like in vertebrates this peptide may be an important hormonal factor in controlling feeding and reproductive process.