Leptin

Adaptive Effects of Endocrine Hormones on Metabolism of Macronutrients during Fasting and Starvation: A Scoping Review

Food deprivation can occur for different reasons. Fasting (<24 h duration) occurs to meet religious or well-being goals. Starvation (>1-day duration) occurs when there is intentional (hunger strike or treatment of a medical condition) or unintentional (anorexia nervosa, drought, epidemic famine, war, or natural disaster) food deprivation. A scoping review was undertaken using the PubMed database to explore 1805 abstracts and review 88 eligible full-text articles to explore the adaptive relationships that emerge between cortisol, insulin, glucagon, and thyroid hormones on the metabolic pathways of macronutrients in humans during fasting and starvation. The collected data indicate that fasting and starvation prime the human body to increase cortisol levels and decrease the insulin/glucagon ratio and triiodothyronine (T3) levels. During fasting, increased levels of cortisol and a decreased insulin/glucagon ratio enhance glycogenolysis and reduce the peripheral uptake of glucose and glycogenesis, whereas decreased T3 levels potentially reduce glycogenolysis. During starvation, increased levels of cortisol and a decreased insulin/glucagon ratio enhance lipolysis, proteolysis, fatty acid and amino acid oxidation, ketogenesis, and ureagenesis, and decreased T3 levels reduce thermogenesis. We present a potential crosstalk between T3 and the above hormones, including between T3 and leptin, to extend their adaptive roles in the metabolism of endogenous macronutrients during food deprivation.

An Overview of Different Vitamin D Compounds in the Setting of Adiposity

A large body of research shows an association between higher body weight and low vitamin D status, as assessed using serum 25-hydroxyvitamin D concentrations. Vitamin D can be metabolised in adipose tissue and has been reported to influence gene expression and modulate inflammation and adipose tissue metabolism in vitro. However, the exact metabolism of vitamin D in adipose tissue is currently unknown. White adipose tissue expresses the vitamin D receptor and hydroxylase enzymes, substantially involved in vitamin D metabolism and efficacy. The distribution and concentrations of the generated vitamin D compounds in adipose tissue, however, are largely unknown. Closing this knowledge gap could help to understand whether the different vitamin D compounds have specific health effects in the setting of adiposity. This review summarises the current evidence for a role of vitamin D in adipose tissue and discusses options to accurately measure vitamin D compounds in adipose tissue using liquid chromatography tandem mass spectrometry (LC/MS-MS).

Chicory: Understanding the Effects and Effectors of This Functional Food

Industrial chicory has been the subject of numerous studies, most of which provide clinical observations on its health effects. Whether it is the roasted root, the flour obtained from the roots or the different classes of molecules that enter into the composition of this plant, understanding the molecular mechanisms of action on the human organism remains incomplete. In this study, we were interested in three molecules or classes of molecules present in chicory root: fructose, chlorogenic acids, and sesquiterpene lactones. We conducted experiments on the murine model and performed a nutrigenomic analysis, a metabolic hormone assay and a gut microbiota analysis, associated with in vitro observations for different responses. We have highlighted a large number of effects of all these classes of molecules that suggest a pro-apoptotic activity, an anti-inflammatory, antimicrobial, antioxidant, hypolipidemic and hypoglycemic effect and also an important role in appetite regulation. A significant prebiotic activity was also identified. Fructose seems to be the most involved in these activities, contributing to approximately 83% of recorded responses, but the other classes of tested molecules have shown a specific role for these different effects, with an estimated contribution of 23-24%.

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

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

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

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

Premature ejaculation: an update on definition and pathophysiology

Premature ejaculation (PE) is the most common male sexual dysfunction, which represents a diagnostic as well as a therapeutic challenge for physicians. However, no universally accepted definition is currently available for PE. As a result, physicians continue to diagnose patients with PE according to major guidelines set by the professional societies. These guidelines either recommend the use of validated questionnaires or patient-reported outcomes. Recent efforts directed toward classifying PE may help provide a better understanding of the prevalence and risk factors of this disorder. While the exact etiology of PE has not been clearly elucidated, several risk factors have been strongly reported in the literature. Clearly, to understand the revised definition of PE, its etiology and pathophysiology is necessary to improve the clinical management of this medical condition and form the basis of future research in this regard. In this review, we highlight the past and current definitions of PE and present an appraisal on the classifications and theories suggested for the etiopathogenesis of PE.

Elevated leptin levels in healthy climacteric women from Northeastern Brazil: an effect of age or adiposity?

OBJECTIVE

Climacterium is associated with elevated leptin levels and increased risk of cardiovascular disorders. Conflicting data diverge on whether high leptin levels in climacterium reflect increasing adipose mass or, at least partially, age-related hormonal changes. This study addresses this issue in women from a Brazilian state with a low human development index.

SUBJECTS AND METHODS

A case-control study was conducted, enrolling 136 women from the state of Maranhão, 52 (38.2%) climacteric and 84 (61.8%) non-climacteric. Biometric, biochemical, hormonal and immunological parameters were analyzed.

RESULTS

Climacteric women showed a moderately increased waist/hip ratio (0.894 versus 0.834, p < 0.05), sustained body mass index (27.46 versus 28.68, p > 0.05) increased leptin levels (9.59 versus 7.13, p < 0.05) and no evidence of metabolic syndrome. No other parameters were altered. The climacteric cohort didn't show significant body fat gains but displayed a typical age-related redistribution of adipose tissue. Even so, leptin levels were significantly elevated compared with non-climacteric women.

CONCLUSIONS

Altogether, these data support the hypothesis that leptin is elevated, at least partially, as a function of age and climacterium and is not necessarily correlated with metabolic dysfunction and systemic inflammation. Further studies are needed to evaluate the impact of higher leptin levels on postmenopausal women. Arch Endocrinol Metab. 2020;64(3):276-81.

Association of NE, leptin, and 5-HT with electrophysiological parameters in patients with primary premature ejaculation

OBJECTIVE

To investigate the possible role of serum norepinephrine (NE), leptin, and 5-hydroxytryptamine (5-HT) and their correlations with sympathetic skin response located in the penis (PSSR) in primary premature ejaculation (PPE).

METHODS

We compared the serum level of NE, leptin, and 5-HT, intravaginal ejaculatory latency time (IELT) and the premature ejaculation diagnostic tool (PEDT) scores between 57 PPE patients and 42 healthy control men as controls, who were recruited between September 2016 and January 2019. Additionally, the amplitude and latency of PSSR were measured and compared between the two groups.

RESULTS

Compared with healthy men, both leptin and NE increased significantly in PPE patients (P = .003, P = .005), while serum 5-HT remarkably decreased (P = .002). Serum leptin, NE, and 5-HT were significantly correlated with the diagnosis of PPE, PSSR amplitude, and latency. Moreover, compared with single serum indicator, NE/5-HT and leptin/5-HT had a stronger correlation with both PSSR amplitude (r = .8377, P < .001; r = .9323, P < .001, respectively) and latency (r = -.8058, P < .001; r = -.8901, P < .001, respectively).

CONCLUSION

Significant differences in leptin, NE, and 5-HT are observed between PPE patients and the controls, which supports the hypothesis of hyperactive sympathetic nerve system (SNS) in PPE. Additionally, leptin/5-HT ratio may serve as an ideal indicator for reflecting SNS activity and predicting treatment response in PPE patients in the future.

Hypothalamic leptin sensitivity and health benefits of time-restricted feeding are dependent on the time of day in male mice

Synchronization between biologic clocks and metabolism is crucial for most species. Here, we examined the ability of leptin, important in the control of energy metabolism, to induce leptin signaling at the molecular as well as the behavioral level throughout the 24-h day in mice fed either a control or a high-fat diet (HFD). Furthermore, we investigated the effects of time-restricted feeding (TRF; a limitation of HFD access to 6 h each day) on energy metabolism during different periods throughout the 24-h day. In control mice, molecular leptin sensitivity was highest at zeitgeber time (ZT)0 (lights on), declining during the light phase, and increasing during the dark phase. Surprisingly, leptin resistance in HFD-fed mice was only present from the middle of the dark to the middle of the light period. Specifically, when TRF occurred from ZT21 to ZT3 (when leptin resistance in HFD-fed mice was most profound), it resulted in a disruption of the daily rhythms of locomotor activity and energy expenditure and in increased plasma insulin levels compared with other TRF periods. These data provide evidence that leptin sensitivity is controlled by the circadian rhythm and that TRF periods may be most efficient when aligned with the leptin-sensitive period.-Boucsein, A., Rizwan, M. Z., Tups, A. Hypothalamic leptin sensitivity and health benefits of time-restricted feeding are dependent on the time of day in male mice.

Association between leptin levels and severity of suicidal behaviour in schizophrenia spectrum disorders

OBJECTIVE

Associations between suicidality and lipid dysregulation are documented in mental illness, but the potential role of leptin remains unclear. We examined the association between leptin and suicidal behaviour in schizophrenia, together with the influence of other clinical and biological indices.

METHOD

We recruited a sample of 270 participants with schizophrenia spectrum diagnoses. Blood samples were analysed for leptin, while symptom severity was assessed by Positive and Negative Syndrome Scale (PANSS) and Inventory of Depressive Symptomatology (IDS-C). Patients' history of suicidal behaviour was categorized into three subgroups based on IDS-C suicide subscale: No suicidal behaviour, mild/moderate suicidal behaviour and severe suicidal behaviour with/without attempts.

RESULTS

Mild/moderate suicidal behaviour was present in 17.4% and severe suicidal behaviour in 34.8%. Both groups were significantly associated with female gender (OR = 6.0, P = 0.004; OR = 5.9, P = 0.001), lower leptin levels (OR = 0.4, P = 0.008; OR = 0.5, P = 0.008) and more severe depression (OR = 1.2, P < 0.001; OR = 1.1, P < 0.001) respectively. Smoking (OR = 2.6, P = 0.004), younger age of onset (OR = 0.9, P = 0.003) and less use of leptin-increasing medications (OR = 0.5, P = 0.031) were associated with severe/attempts group, while higher C-reactive protein CRP (OR = 1.3, P = 0.008) was associated with mild/moderate group.

CONCLUSION

Lower leptin levels were associated with higher severity of suicidal behaviour in schizophrenia.

Prenatal n-3 long-chain fatty acid status and offspring metabolic health in early and mid-childhood: results from Project Viva

Higher maternal and biomarker levels of n-3 long-chain polyunsaturated fatty acids (LCPUFAs) have been associated with improved perinatal outcomes and may also influence offspring metabolic health. Past studies were not powered to examine metabolic outcomes and few have specifically targeted metabolically vulnerable populations. We examined the associations of prenatal n-3 LCPUFA status with markers of metabolic health in early and mid-childhood in the full population as well as stratified by maternal glucose tolerance. Our data consisted of 1418 mother-child dyads from Project Viva, a longitudinal, prospective pre-birth cohort enrolled in eastern Massachusetts. We assessed maternal dietary intake of fish and n-3 LCPUFA in mid-pregnancy using a validated food frequency questionnaire. N-3 LCPUFA levels were quantified in maternal second trimester and umbilical cord plasma using liquid-gas chromatography. We assessed offspring anthropometry, adiposity, and blood pressure at early (median age: 3.2 years) and mid-childhood (median age: 7.7 years); and assayed blood samples collected at these visits for metabolic biomarkers. We report here multivariable effect estimates and 95% CI. Early childhood BMI z-score was on average 0.46 (1.03) units and waist circumference 51.3 (3.7) cm. At mid-childhood these measures were 0.39 (1.00) units and 60.0 (8.3) cm, respectively. Higher cord plasma DHA levels were associated with lower BMI z-score ((Q)uartile 4 vs. Q1: -0.21, 95% CI: -0.38, -0.03), waist circumference (Q4 vs. Q1: -0.63, 95% CI: -1.27, 0.00 cm), and leptin levels (Q4 vs. Q1: -0.36, 95% CI: -0.77, 0.05 ng/mL) in early childhood. These associations were strongest and reached significance in offspring of women with isolated hyperglycemia vs. better or worse glycemic status. Higher maternal DHA + EPA (Q4 vs. Q1: -1.59, 95% CI: -2.80, -0.38 μg/mL) and fish (≥3 vs. 0 portions/week: -2.18, 95% CI: -3.90, -0.47 μg/mL) intake was related to lower adiponectin in early childhood. None of these associations persisted with mid-childhood outcomes. We did not find associations with any of the other outcomes. This study supports early and possibly transient effects of prenatal n-3 LCPUFA status on anthropometric measures and adipokine levels. It also raises the possibility that offspring of women with isolated hyperglycemia derive the most benefits from higher n-3 LCPUFA status.

Steroidogenic genes expressions are repressed by high levels of leptin and the JAK/STAT signaling pathway in MA-10 Leydig cells

The adipose tissue is an important endocrine organ secreting numerous peptide hormones, including leptin. Increased circulating levels of leptin, as a result of hormonal resistance in obese individuals, may contribute to lower androgen production in obese males. However, the molecular mechanisms involved need to be better defined. Androgens are mainly produced by Leydig cells within the testis. In male rodents, activation of the leptin receptor modulates a cascade of intracellular signal transduction pathways which may lead to regulation of transcription factors having influences on steroidogenesis in Leydig cells. Thus, as a result of high leptin levels interacting with its receptor and modulating the activity of the JAK/STAT signaling pathway, the activity of transcription factors important for steroidogenic genes expressions may be inhibited in Leydig cells. Here we show that Lepr is increasingly expressed within Leydig cells according to postnatal development. Although high levels of leptin (corresponding to obesity condition) alone had no effect on Leydig cells' steroidogenic genes expression, it downregulated cAMP-dependent activations of the cholesterol transporter Star and of the rate-limiting steroidogenic enzyme Cyp11a1. Our results suggest that STAT transcriptional activity is downregulated by high levels of leptin, leading to reduced cAMP-dependent steroidogenic genes (Star and Cyp11a1) expressions in MA-10 Leydig cells. However, other transcription factors such as members of the SMAD and NFAT families may be involved and need further investigation to better define how leptin regulates their activities and their relevance for Leydig cells function.

Alteration of Leptin and Adiponectin in Multistep Colorectal Tumorigenesis

BACKGROUND

There is an established link between obesity related metabolic derangement and colorectal cancer development. Recently, we developed a metabolic-colorectal cancer risk score. In this follow-up study, we studied its association with colorectal neoplasm by measuring two major metabolic syndrome biomarkers, leptin and adiponectin.

OBJECTIVES

To evaluate the serum levels of leptin and adiponectin in patients with colorectal polyps and colorectal cancer and to determine any correlation with metabolic risk score.

RESULTS

In total, 130 individuals were studied: 30 controls without colonic pathology, 18 with colonic adenoma (CAP), and 82 with colorectal adenocarcinoma (CRC, 17 cases of T1-2 and 65 cases of T3-4). The metabolic risk scores in CAP and T1-2 CRC were higher than those in the controls and T3-4 CRC cases. There were no statistically significant differences in leptin levels among CAPs, CRCs, and controls. Both leptin and adiponectin levels reflected differences in body mass index and metabolic risk scores. Cases in the CAP group and early T-stage CRC groups had lower adiponectin levels (14.03 and 13.01 mg/ml, respectively) than the no polyps group (19.5mg/ml, p = 0.03). The average serum adiponectin level in the invasive cancer group (18.5 ng/ml) was comparable with that of the control group.

CONCLUSIONS

The level of serum adiponectin was positively correlated with the metabolic risk score. Decreased serum adiponectin was significantly associated with the development of colorectal adenoma and early stage colorectal carcinoma.

Development and validation of an assay for measurement of leptin in pig saliva

Background

Leptin has been measured in human in saliva samples. However, the low leptin concentration found in this biological fluid makes necessary the use of high sensitive methods. To the authors’ knowledge, leptin has not been measured in porcine saliva. This study aimed to develop and validate a time-resolved immunofluorometric assay (TR-IFMA) for salivary leptin measurements in pigs, using a species-specific antibody, and to evaluate how salivary leptin changes with body weight, food ingestion, and in experimental models of stress and inflammation. Polyclonal antibodies were produced in rabbits immunized with recombinant porcine leptin and used to develop a sandwich TR-IFMA.

Results

The method had intra-assay and inter-assay coefficients of variation lower than 10 and 16 %, respectively. The assay was accurate and the low limit of detection allowed detection of leptin in all analyzed samples. Salivary leptin concentration was positively correlated to body weight (r = 0.58, P = 0.01) and increased after food ingestion (P < 0.001) and after 24 h of applying a model of experimental inflammation by turpentine injection (P < 0.05). However, it did not significantly change after a model of acute stress consisting of a nose snare restraining.

Conclusion

These results indicate that the developed assay can measure leptin in porcine saliva in a reliable way and that leptin in saliva is influenced by body weight, food ingestion and inflammation.

Serum inhibin and leptin: Risk factors for pre-eclampsia?

BACKGROUND

Pre-eclampsia and eclampsia are parts of the broader spectrum of hypertensive disorders complicating pregnancy. This study aims to examine the association between serum inhibin and leptin levels and pre-eclampsia.

METHODS

This study included 98 consecutive cases of pregnant women with pre-eclampsia, together with their 98 pregnant controls, matched for age, gestational week and time period of delivery. Maternal venous blood samples were obtained within 24h before delivery. In addition to serum inhibin and leptin, birth order, multiple pregnancy, maternal age, maternal overweight/obesity, maternal education, maternal smoking and family history of diabetes/hypertension, were examined as risk factors. Multivariate logistic regression analysis was performed.

RESULTS

At the univariate analysis, serum inhibin and leptin levels were significantly higher in cases vs.

CONTROLS

Pre-eclampsia occurred more frequently in primiparous women, whereas overweight and obesity were also associated with pre-eclampsia. At the multivariate analysis, higher serum inhibin levels were associated with pre-eclampsia (multivariate OR=1.09, 95%CI: 1.03-1.17, p=0.004, increase per 0.1ng/mL). On the other hand, leptin was not independently associated with the occurrence of pre-eclampsia (multivariate OR=1.02, 95%CI: 0.95-1.09, p=0.631, increase per 10ng/mL).

CONCLUSIONS

Elevated serum inhibin levels seem to be associated with pre-eclampsia, reflecting placental dysfunction. Increased serum leptin levels may merely reflect an elevated maternal body mass index, which is a well-known risk factor for pre-eclampsia.

Roles of leptin, adiponectin and resistin in the transcriptional regulation of steroidogenic genes contributing to decreased Leydig cells function in obesity

The increase in obesity rate is a major public health issue associated with increased pathological conditions such as type 2 diabetes or cardiovascular diseases. Obesity also contributes to decreased testosterone levels in men. Indeed, the adipose tissue is an endocrine organ which produces hormones such as leptin, adiponectin and resistin. Obesity results in pathological accumulations of leptin and resistin, whereas adiponectin plasma levels are markedly reduced, all having a negative impact on testosterone synthesis. This review focuses on current knowledge related to transcriptional regulation of Leydig cells' steroidogenesis by leptin, adiponectin and resistin. We show that there are crosstalks between the regulatory mechanisms of these hormones and androgen production which may result in a dramatic negative influence on testosterone plasma levels. Indeed leptin, adiponectin and resistin can impact expression of different steroidogenic genes such as Star, Cyp11a1 or Sf1. Further investigations will be required to better define the implications of adipose derived hormones on regulation of steroidogenic genes expression within Leydig cells under physiological as well as pathological conditions.

Serum leptin and adiponectin levels in children with type 1 diabetes mellitus - Relation to body fat mass and disease course

PURPOSE

Leptin and adiponectin are adipokines presenting a wide range of impacts, including glycemic balance regulations. Insulin is one of the main regulators of adipose tissue function. In type 1 diabetes mellitus (T1DM) endogenous insulin secretion is replaced by the exogenous supply, which is not regulated naturally. The aim of the study was to establish serum leptin and adiponectin levels, and their relations to body fat mass and disease course in children with T1DM.

MATERIAL/METHODS

The study included 75 children with T1DM and the control group of 20 healthy coevals. All children had estimated serum leptin and adiponectin concentrations, lipid profile, and bioelectrical impedance analysis.

RESULTS

Serum leptin concentrations in children with T1DM were not significantly different from the control group (p=0.067, mean values±SD: 3.11±2.98 vs. 5.29±5.06μg/l, respectively), and related positively to body fat mass in both groups. Adiponectin serum concentrations were significantly higher in children with T1DM than in the control group (p<0.001; mean values: 18.82±9.31 vs. 12.10±5.53μg/ml, respectively), and were not related to the body fat content in the study group. Both, leptin and adiponectin, showed no relation to any of the analyzed parameters of the disease course.

CONCLUSIONS

Differences observed between children with T1DM and their healthy coevals, when similar in terms of age, body weight, and body fat mass, seem not to depend directly on the disease duration, its metabolic control or insulin supply.

Peroxisome proliferator-activated receptor gamma signaling in human sperm physiology

Peroxisome proliferator-activated receptor gamma (PPARγ) is a member of the PPARs, which are transcription factors of the steroid receptor superfamily. PPARγ acts as an important molecule for regulating energy homeostasis, modulates the hypothalamic-pituitary-gonadal (HPG) axis, and is reciprocally regulated by HPG. In the human, PPARγ protein is highly expressed in ejaculated spermatozoa, implying a possible role of PPARγ signaling in regulating sperm energy dissipation. PPARγ protein is also expressed in Sertoli cells and germ cells (spermatocytes). Its activation can be induced during capacitation and the acrosome reaction. This mini-review will focus on how PPARγ signaling may affect fertility and sperm quality and the potential reversibility of these adverse effects.

Associations of Circulating Gut Hormone and Adipocytokine Levels with the Spectrum of Gastroesophageal Reflux Disease

OBJECTIVE

The pathogenesis of gastroesophageal reflux disease (GERD) is complex and poorly understood. We aim to investigate the association of various circulating peptide hormones with heterogenous manifestations of GERD.

METHODS

One hundred and four patients that had experienced typical GERD symptoms (heartburn and/or acid regurgitation) for at least 3 episodes per week in the past 3 months were enrolled. All patients received a baseline assessment of symptom severity and frequency with the Reflux Disease Questionnaire and an upper endoscopy to classify GERD into erosive esophagitis (EE, n = 67), non-erosive esophagitis (NE, n = 37), and Barrett's esophagus (BE, n = 8). Fifty asymptomatic subjects with an endoscopically normal esophagus were recruited as the control group. Complete anthropometric measures and blood biochemistry were obtained and fasting serum levels of adipocytokines (adiponectin and leptin) and gut hormones (ghrelin and peptide YY (PYY)) were determined by enzyme-linked immunosorbent assay in all subjects.

RESULTS

All circulating peptide hormone levels were not statistically different between the GERD and control groups. However, GERD patients appeared to have lower PYY levels [median (25th-75th percentile), 80.1 (49.8-108.3) vs. 99.4 (65.8-131.9) pg/ml, p = 0.057] compared with control subjects. Among the GERD patients, ghrelin levels were inversely associated with the frequency and severity of acid regurgitation. In male GERD patients, EE was associated with significantly higher PYY levels [107.0 (55.0-120.8) vs. 32.8 (28.7-84.5) pg/ml, p = 0.026] but lower adiponectin levels [6.7 (5.6-9.3) vs. 9.9 (9.6-10.6) μg/ml, p = 0.034] than NE. Patients with BE had significantly lower adiponectin levels [6.0 (5.1-9.2) vs. 9.2 (7.1-11.2) μg/ml, p = 0.026] than those without BE.

CONCLUSIONS

Humoral derangement of circulating peptide hormones might participate in inflammation and symptom perception in patients suffering from GERD. Further studies to clarify the exact role of these hormones in the pathogenesis of GERD are warranted.

Leptin in Alzheimer's disease

Alzheimer's disease (AD) is the most common cause of progressive dementia in the elderly population. AD is histologically characterized by accumulation of amyloid-β protein (Aβ) on extracellular plaques and deposition of hyperphosphorylated tau protein in intracellular neurofibrillary tangles. Several studies have shown that obesity may precede dementia and that lifestyle factors play a critical role in the onset of AD. Furthermore, accumulating evidence indicates that obesity is an independent risk factor for developing AD. In this scenario, the understanding of the role of adipose tissue in brain health is essential to clarify the establishment of demential processes. The objective of this work was to review studies regarding leptin, an anorexigenic peptide hormone synthesized in adipocytes, in the context of dementia. Some authors proposed that leptin evaluation might be a better predictor of dementia than traditional anthropometric measures. Leptin, once established as a biomarker, could enhance the understanding of late-onset AD risk over the life course, as well as the clinical progression of prodromal state to manifested AD. Other studies have proposed that leptin presents neuroprotective activities, which could be explained by inhibiting the amyloidogenic process, reducing the levels of tau protein phosphorylation and improving the cognitive function.

Serum leptin in Egyptian patients with fibromyalgia syndrome: relation to disease severity

AIM

Recently, a large body of studies has focused on the leptin levels in psychiatric disorders. This study aimed to measure serum leptin levels in fibromyalgia syndrome (FMS) due to a significantly higher prevalence of psychiatric disorder and to determine the relationship between leptin and FMS.

METHODS

The present study was a cross-sectional descriptive study. Fifty FMS female patients and 50 healthy females serving as a control group were included. Serum samples tested for serum leptin levels were determined by a specific enzyme-linked immunosorbent assay (ELISA).

RESULTS

Serum leptin levels were significantly lower in FMS patients compared to the control group. The mean serum leptin in patients with FMS was 7.1 ± 6.8 ng/mL compared to 9.4 ± 4.5 ng/mL in the controls (mean difference, -2.48, 95% CI: -4.78, -0.18, P = 0.035). Serum leptin level is inversely correlated with visual analogue scale (VAS) of pain (P = 0.016), VAS of fatigue (P = 0.002), VAS of global severity (P = 0.011), VAS of anxiety (P = 0.027), global self-rating index (P = 0.020), Health Assessment Questionnaire score (P = 0.016), fibromyalgia impact questionnaire (FIQ) (P = 0.025), Beck Depression Inventory (P = 0.002), tender points (TPs) count (P = 0.041), TPs score (P = 0.015), and Pittsburg Sleep Quality Index (P = 0.006). Mean serum leptin levels were also significantly lower in FMS patients with post-exertion pain (P = 0.010), depression (P = 0.029), mood disturbance (P = 0.018), anxiety (P = 0.030), short memory difficulties (P = 0.017), sleep disturbance (P = 0.028), restless leg syndrome (P = 0.016), temperomandibular joint syndrome affection (P = 0.043), palpitation (P = 0.022), and irritable bowel syndrome (P = 0.028) than those without.

CONCLUSION

We found a significant decrease in serum leptin in FMS patients compared to controls and this decrease correlated with disease severity.

Scleroderma-related lung disease: are adipokines involved pathogenically?

Scleroderma is a systemic autoimmune disease of unknown etiology whose characteristic features include endothelial cell dysfunction, fibroblast proliferation, and immune dysregulation. Although almost any organ can be pathologically involved in scleroderma, lung complications including interstitial lung disease (ILD) and pulmonary arterial hypertension (PAH) are the leading cause of death in patients with this condition. Currently, the molecular mechanisms leading to development of scleroderma-related lung disease are poorly understood; however, the systemic nature of this condition has led many to implicate circulating factors in the pathogenesis of some of its organ impairment. In this article we focus on a new class of circulating factors derived from adipose-tissue called adipokines, which are known to be altered in scleroderma. Recently, the adipokines adiponectin and leptin have been found to regulate biological activity in endothelial, fibroblast, and immune cell types in lung and in many other tissues. The pleiotropic nature of these circulating factors and their functional activity on many cell types implicated in the pathogenesis of ILD and PAH suggest these hormones may be mechanistically involved in the onset and/or progression of scleroderma-related lung diseases.

Reproducibility of estradiol and testosterone levels in postmenopausal women over 5 years: results from the breakthrough generations study

Prospective cohort studies examining sex hormones in relation to cancer risk have generally collected blood samples at 1 time point, with an assumption that hormone levels measured in these samples will be reliable markers of true levels at other times. In postmenopausal women, body fat is a major source of estradiol; therefore, changes in adiposity may affect the correlation of single measurements to more relevant long-term averages. To estimate the intraclass correlation coefficient (ICC) for estradiol and testosterone, we collected repeat blood samples from 119 postmenopausal women (average age = 59.4 (standard deviation, 4.7) years) from the United Kingdom during 2004-2005 and again during 2010-2011. The ICCs (adjusted for assay variation) were 0.73 (95% confidence interval: 0.63, 0.82) for total estradiol and 0.59 (95% confidence interval: 0.47, 0.72) for total testosterone. The ICCs were 3%-5% larger after adjustment for change in body mass index (weight (kg)/height (m)(2)) or leptin, which are 2 markers of change in adiposity. There was no increase in ICCs after adjustment for change in age, alcohol consumption, smoking, exercise, time between waking and blood collection, or season. The results suggest that other factors account for within-woman variation in these sex hormones.

Alterations of Lipid-Lipoprotein and Leptin in Bipolar Disorder Associated with Clinic Process

INTRODUCTION

Obesity is more common among patients with bipolar disorder as compared to normal population. There are studies showing increased leptin levels in obese patients. The aim of the present study was to investigate the alterations in leptin levels, body mass index (BMI), and lipid-lipoprotein levels during manic period, as well as during euthymic period, after one month in patients with bipolar disorder.

METHODS

Thirty-one adult patients, who had been hospitalized in the psychiatry clinic because of manic period of bipolar disorder, were included in the present study. Serum leptin and lipid-lipoprotein levels and BMI of the patients were analyzed both on the first day and 30th day of hospitalization after they became euthymic.

RESULTS

Total cholesterol and triglyceride levels significantly increased in male patients (p<.05). The increase in total cholesterol and LDL-C levels was not significant in female patients (p=.066 and p=.056, respectively). BMI was significantly, but slightly increased in both genders (.56±.14 kg/m²), however, such a change was not observed in serum leptin levels.

CONCLUSION

Results of the present study demonstrated that clinical improvement in bipolar patients showed different association in each gender with the alterations in BMI and serum lipid and/or lipoprotein levels. Such an alteration might have resulted from direct or indirect effect of drugs, as well as from lifestyle changes.

High-fat diet induces leptin resistance in leptin-deficient mice

The occurrence of type II diabetes is highly correlated with obesity, although the mechanisms linking the two conditions are incompletely understood. Leptin is a potent insulin sensitiser and, in leptin-deficient, insulin insensitive, Lep(ob/ob) mice, leptin improves glucose tolerance, indicating that leptin resistance may link obesity to insulin insensitivity. Leptin resistance occurs in response to a high-fat diet (HFD) and both hyperleptinaemia and inflammation have been proposed as causative mechanisms. Scrutinising the role of hyperleptinaemia in this process, central hyperleptinaemia in Lep(ob/ob) mice was induced by chronic i.c.v. infusion of leptin (4.2 μg/day) over 10 days. This treatment led to a dramatic decline in body weight and food intake, as well as an improvement in glucose tolerance. Transfer to HFD for 4 days markedly arrested the beneficial effects of leptin on these parameters. Because Lep(ob/ob) mice are exquisitely sensitive to leptin, the possibility that leptin could reverse HFD-induced glucose intolerance in these animals was investigated. HFD led to increased body weight and glucose intolerance compared to a low-fat diet (LFD). Older and heavier Lep(ob/ob) mice were used as body weight-matched controls. Mice in each group received either i.p. leptin (1.25 mg/kg) or vehicle, and glucose tolerance, food intake and the number of phosphorylated signal transducer and activator of transcription (pSTAT)3 immunoreactive cells in the arcuate nucleus (ARC) and ventromedial hypothalamus (VMH) were analysed. Leptin improved glucose tolerance (P = 0. 019) and reduced food intake in Lep(ob/ob) mice on LFD (P ≤ 0.001) but was ineffective in mice on HFD. Furthermore, when leptin was administered centrally, the glucose tolerance of Lep(ob/ob) mice on HFD was significantly impaired (P = 0.007). Although leptin induced the number of pSTAT3 immunoreactive cells in the ARC and VMH of Lep(ob/ob) mice on LFD, HFD was associated with elevated pSTAT3 immunoreactivity in vehicle-treated Lep(ob/ob) mice that was unaffected by leptin treatment, suggesting central leptin resistance. Negating central inflammation by co-administering a c-Jun n-terminal kinase (JNK) inhibitor reinstated the glucose-lowering effects of leptin. These findings demonstrate that Lep(ob/ob) mice develop leptin resistance on a HFD independent of hyperleptinaemia and also indicate that the JNK inflammatory pathway plays a key role in the induction of diet-induced glucose intolerance.

Changes in estradiol and testosterone levels in postmenopausal women after changes in body mass index

CONTEXT

Endogenous sex hormones are risk factors for postmenopausal breast cancer. A potential route for favorable hormonal modification is weight loss.

OBJECTIVE

The objective of the study was to measure change in plasma estradiol and testosterone levels in postmenopausal women in relation to change in body mass index (BMI) and plasma leptin.

SETTING

The setting was a cohort study of over 100,000 female volunteers from the general population, United Kingdom.

PARTICIPANTS

The participants were a sample of 177 postmenopausal women aged over 45 years who provided blood samples during 2004-2005 and again during 2010-2011.

MAIN OUTCOME MEASURE

Outcomes were percentage change in plasma estradiol and testosterone levels per 1 kg/m² change in BMI and per 1 ng/mL change in plasma leptin.

RESULTS

Among women with reduction in BMI, estradiol decreased 12.7% (95% confidence interval: [6.4%, 19.5%]; P < .0001) per kg/m² and among women with increased BMI estradiol increased 6.4% [0.2%, 12.9%] (P = .042). The corresponding figures for testosterone were 10.7% [3.0%, 19.0%] (P = .006) and 1.9% [-5.4%, 9.7%] (P = .61) per kg/m². For women with decreases and increases in leptin, estradiol decreased by 3.6% [1.3%, 6.0%] (P = .003) per ng/mL and increased by 1.7% [-0.3%, 3.6%] (P = .094), respectively. The corresponding figures for testosterone were 4.8% [2.0%, 7.8%] (P = .009) and 0.3% [-2.0%, 2.6%] (P = .82) per ng/mL.

CONCLUSIONS

In postmenopausal women, changes in BMI and plasma leptin occurring over several years are associated with changes in estradiol and testosterone levels. The results suggest that fat loss by an individual can result in substantial decreases in postmenopausal estradiol and testosterone levels and provides support for weight management to lessen breast cancer risk.

[Leptin: Involvement in the pathophysiology of breast cancer]

More than one million new cases of breast cancer are diagnosed each year worldwide and more than 400,000 deaths occur due to this pathology. Obesity is a risk factor for postmenopausal breast cancer and the place held by the adipose tissue and secretions (i.e. adipokines) begins to be recognized. Indeed, firstly, plasma adipokine levels, modulated in obesity situation, could have effects "remotely" on mammary carcinogenesis and, secondly, breast cancer cells are surrounded by adipocyte microenvironment, which is probably more important in the case of obesity, and may be locally influenced by it. In this context, leptin appears to be strongly involved in mammary carcinogenesis and may contribute to the angiogenesis process and local pro-inflammatory mechanisms, especially in obese patients for whom increased metastatic potential and risk of mortality are described.

Maternal/fetal determinants of insulin resistance in women during pregnancy and in offspring over life

Insulin resistance is a component of the pathophysiology of both type 2 diabetes and gestational diabetes mellitus (GDM), but is also characteristic of normal glycemic physiology during pregnancy. In recent years, many studies have tried to understand determinants of insulin resistance in normal pregnancy and GDM, revealing that the placenta is capable of secreting many cytokines and hormones, classically considered as adipokines. More specifically, it appears that leptin and TNFα could be implicated in gestational insulin resistance and GDM pathophysiology. In addition, the maternal metabolic milieu was also identified as a key determinant of later insulin resistance in offspring, a phenomenon often described as 'fetal programming'. This article reviews the established risk factors and the more novel suspected biomarkers involved in maternal insulin resistance during pregnancy as well as the maternal and early life determinants of insulin resistance in offspring later in their life. We are also highlighting recent reports of the potential mechanisms involved in 'programming' of insulin resistance such as epigenetic modulation.

Targeting adipocyte apoptosis: a novel strategy for obesity therapy

Obesity is an increasing world problem that may cause several metabolic complications including insulin resistance, hyperlipidemia, hypertension, and atherosclerosis. Development of therapeutic drugs for obesity has been proven difficult. Current strategies for weight reduction are inhibition of food intake through the central nervous system or blocking the absorption of lipids in the gut. These therapies have many side effects, so new treatments are urgently needed. Fat loss could also be achieved through a decrease in the size and number of adipocytes through apoptosis. Apoptosis is a normal phenomenon of cell death for the purpose of maintaining homeostasis. Induction of apoptosis is a reasonable way to remove adipocytes in obese patients. It is reported that several adipokines and natural products play roles in induction of adipocyte apoptosis. Here we review the recent progress of the roles and mechanisms of adipocyte apoptosis induced by leptin, tumor necrosis factor-α (TNF-α), and natural compounds.

Obesity alters circadian behavior and metabolism in sex dependent manner in the volcano mouse Neotomodon alstoni

The aim of the present study is to evaluate whether circadian locomotor activity, and the daily profile of plasma parameters related to metabolic syndrome (nutrients: glucose and triacylglycerides, and hormones: insulin and leptin), differ between male and female Neotomodon alstoni mice, both lean and obese. Young adult animals were captured in the field and kept at the laboratory animal facility. After 6 to 7 months feeding the animals ad libitum with a regular diet for laboratory rodents, 50-60% of mice became obese. Comparisons between sexes indicated that lean females were more active than males; however obese females reduced their nocturnal activity either in LD or DD, and advanced the phase of their activity-onset with respect to lights off. No differences in food intake between lean and obese mice, either during the day or night, were observed. Daily profiles of metabolic syndrome-related plasma parameters showed differences between sexes, and obesity was associated with increased values, especially leptin (500% in females and 273% in males) and insulin (150% in both females and males), as compared with lean mice. Our results indicate that lean mice display behavioral and endocrine differences between sexes, and obesity affects the parameters tested in a sex-dependent manner. The aforementioned leads us to propose N. alstoni, studied in captivity, could be an interesting model for the study of sex differences in the effects of obesity.

Increased leptin/leptin receptor pathway affects systemic and airway inflammation in COPD former smokers

Background

Leptin, a hormone produced mainly by adipose tissue, regulates food intake and energy expenditure. It is involved in inflammatory diseases such as chronic obstructive pulmonary disease (COPD) and its deficiency is associated with increased susceptibility to the infection. The leptin receptor is expressed in the lung and in the neutrophils.

Methods

We measured the levels of leptin, tumor necrosis factor alpha (TNF-α) and soluble form of intercellular adhesion molecule-1 (sICAM-1) in sputum and plasma from 27 smoker and former smoker patients with stable COPD using ELISA methods. Further we analyzed leptin and its receptor expression in sputum cells from 16 COPD patients using immunocytochemistry.

Results

In plasma of COPD patients, leptin was inversely correlated with TNF-α and positively correlated with the patient weight, whereas the levels of sICAM-1 were positively correlated with TNF-α. In sputum of COPD patients leptin levels were correlated with forced expiratory volume in 1 second/forced vitality capacity. Additionally, increased levels of sputum leptin and TNF-α were observed in COPD former smokers rather than smokers. Further the expression of leptin receptor in sputum neutrophils was significantly higher in COPD former smokers than in smokers, and the expression of leptin and its receptor was positively correlated in neutrophils of COPD former smokers.

Conclusion

Our findings suggest a role of leptin in the local and systemic inflammation of COPD and, taking into account the involvement of neutrophils in this inflammatory disease, describe a novel aspect of the leptin/leptin receptor pathway in the regulation of host defense after smoking cessation.

Upregulation of leptin-receptor in placental cells by hypoxia

OBJECTIVE

Leptin and its receptor (Ob-R) are co-expressed in human placenta suggesting auto- and paracrine mechanisms of the hormone. So far it is unclear, how changes in the placental environment affect Ob-R expression. Hence, the main purpose of the study was to investigate leptin receptor expression and regulation under hypoxic conditions. The influences of hypoxia and leptin on signal transduction and cell proliferation in chorioncarcinoma cell lines as well as primary villous trophoblasts were determined.

RESULTS

We found a time-dependent induction of leptin receptor mRNA and protein in placental cells under hypoxic conditions. In contrast, soluble leptin receptor expression did not change under oxygen deprivation. Leptin treatment neither activated the p42/p44 nor the STAT3 pathway in placental cells, being independent of hypoxic or normoxic conditions. Furthermore, leptin added to the culture medium in high concentrations was unable to interfere with the rate of proliferation.

CONCLUSION

Our data demonstrate that hypoxia leads to an increase of Ob-R expression in placental cells. Interestingly, leptin-dependent signal transduction and proliferation remained unaffected. A possible role of the soluble leptin receptor in modulating free leptin levels will be discussed.

A potential role for adjunctive vitamin D therapy in the management of weight gain and metabolic side effects of second-generation antipsychotics

Second-generation antipsychotic (SGA) medications introduced about 20 years ago are increasingly used to treat psychiatric illnesses in children and adolescents. There has been a five-fold increase in the use of these medications in U.S. children and adolescents in the past decade. However, there has also been a parallel rise in the incidence of side effects associated with these medications, such as obesity, dyslipidemia, insulin resistance, and diabetes mellitus. Despite the severity of these complications and their financial impact on the national healthcare budget, there is neither a clear understanding of the mechanisms contributing to these side effects nor the best ways to address them. Studies that examined lifestyle modification and pharmaceutical agents have yielded mixed results. Therefore, clinical studies using agents, such as vitamin D, which are inexpensive, readily available, with low side effects profile, and have mechanisms to counteract the metabolic side effects of SGA agents, are warranted. Vitamin D is a prohormone with skeletal and extraskeletal properties that could potentially reduce the severity of these metabolic side effects. Its role as an adjunctive therapy for the management of metabolic side effects of SGA agents has not been adequately studied. Effective strategies to curb these side effects will improve the overall health of youths with psychiatric illnesses who receive SGAs. Herein we present a pilot study on the use of vitamin D in patients on treatment with SGAs.

Strain-specific outcomes of repeated social defeat and chronic fluoxetine treatment in the mouse

Social stress is a risk factor for affective disorders in vulnerable individuals. Although the biological nature of stress susceptibility/resilience remains to be elucidated, genetic variation is considered amongst the principal contributors to brain disorders. Furthermore, genetic predisposition may be determinant for the therapeutic outcome, as proposed for antidepressant treatments. In the present studies we compared the inherently diverse genetic backgrounds of 2 mouse strains by assessing the efficacy of a chronic antidepressant treatment in a repeated social stress procedure. C57BL/6J and BalbC mice underwent 10-day social defeats followed by 28-day fluoxetine treatment (10 mg/kg/mL, p.o.). In C57BL/6J, most of the social defeat-induced changes were of metabolic nature including persistently altered feed efficiency and decreased abdominal fat stores that were ameliorated by fluoxetine. BalbC mouse behavior was persistently affected by social defeat both in the social avoidance and the forced swim tests, and in either procedure it was restored by chronic fluoxetine, whereas their endocrine parameters were mostly unaffected. The highlighted strain-specific responsivity to the metabolic and behavioral consequences of social defeat and to the chronic antidepressant treatment offers a promising research tool to further explore the underlying neural mechanisms and genetic basis of stress susceptibility and treatment response.

Fat and water 1H MRI to investigate effects of leptin in obese mice

Leptin is known to be associated with regulation of body weight and fat content. The effects of exogenous leptin on abdominal visceral (VS) and subcutaneous (SC) fat volume and hepatic fat-to-water ratio in leptin-deficient obese mice were investigated by (1)H magnetic resonance imaging (MRI). Chemical shift-selected fat and water (1)H MRI of control and leptin-treated mice were obtained 1 day before treatment and after 7 days of treatment (0.3 mg/kg/day). Hepatic fat-to-water ratio and VS fat volume decreased significantly with treatment, whereas SC fat volume did not change. Noninvasive measurement of fat and water content in different body regions using MRI should prove useful for evaluating new drugs for the treatment of obesity and other metabolic disorders.

Alterations of behavioral and endocrinological reactivity induced by 3 brief social defeats in rats: relevance to human psychopathology

In the realm of animal models of psychopathology, social stress based procedures rely on robust theoretical prerequisites to meet construct validity criteria for the target syndromes. In order to further assess the relevance for human psychopathology of a social defeat based model in rats, known to elicit consistent behavioral and hormonal changes, we expanded its characterization on the basis of both behavioral parameters and peripheral biomarkers thought to be pertinent for clinical symptoms. Rats were subjected to 3 daily social defeat experiences that shortly thereafter led to the insurgence of defensive behaviors, anhedonia, and body weight loss. HPA axis showed an activated response when rats were sampled as early as after the first social defeat experience, while none of the peripheral immune, metabolic, and neurotrophic factors examined were concurrently affected. With the aim of determining the long-term bio-behavioral sequelae of the social defeat experience, rats were assessed also 3 weeks after the social defeats. At this time, behavioral changes were still observed, including decreased general activity and sociality in a social avoidance test, increased immobility and decreased escape responses in a forced swim test. These alterations were not paralleled by alterations in anhedonia nor HPA axis responses from controls, nor where evident changes in the humoral component of the immune response nor in brain derived neurotrophic factor levels, whereas a substantial increase in leptin levels was observed in previously socially defeated rats compared to control. Overall these data depict a very complex set of alterations induced both acutely and long-term by social stress in endocrinological and behavioral reactivity of rats.

Suprachiasmatic Nuclei May Regulate the Rhythm of Leptin Hormone Release in Syrian Hamsters (Mesocricetus Auratus)

The suprachiasmatic nuclei (SCN) generate the circadian rhythm of many hormones. The hormone leptin is a metabolic signal that informs the brain about fat and energy stores of the body. We investigated whether the rhythm of leptin hormone release in Syrian hamsters is directly controlled by the SCN. Three experiments were performed: in the first, hamsters were SCN-lesioned; in the second, hamsters were exposed to different feeding regimes; and in the third, hamsters were adrenalectomized and implanted with cortisol capsules to maintain constant glucocorticoid release. Blood samples were collected before and after the experiments at different clock times and examined for leptin levels by enzyme-linked immunosorbant assay (ELISA). Different feeding regimes and constant glucocorticoid release did not alter the rhythm of leptin release; whereas, SCN lesions abolished the rhythm. The results of the present study suggest the rhythm in leptin release in Syrian hamsters may be controlled by the SCN.

Correlates of serum leptin and insulin-like growth factor-I concentrations in normal weight and overweight/obese Iranian women

BACKGROUND

Leptin and insulin-like growth factor-I (IGF-I) are two interrelated hormones that are implicated in the development or progression of coronary artery disease (CAD) and some cancers. The aim of this study was to investigate the relation between serum leptin and total IGF-I concentrations and to identify their correlations with age or anthropometric and body composition variables in healthy normal weight and overweight/obese Iranian women.

METHODS

The percent of body fat (BF%), fat mass (FM), fat-free mass (FFM), and waist/hip ratio (WHR) were determined in 51 healthy normal weight (body mass index [BMI] 18.5-24.9 kg/m(2)) and 50 overweight/obese (BMI > or = 25 kg/m(2)) Iranian reproductive-age women. Serum leptin and total IGF-I concentrations were measured by double-antibody sandwich assay and enzyme-linked immunosorbent assay (ELISA), respectively. Statistical analysis was performed by Mann-Whitney U test and Spearman's rank-correlation test. Multivariate linear regression analysis was performed with ranked-transformed data to obtain partial correlation coefficient.

RESULTS

In this group of healthy, premenopausal Iranian women, variance of serum leptin concentration was independently explained by FM (partial rho = 0.295, p < 0.01), and variance of the total IGF-I concentration was explained by age (partial rho = -0.214, p = 0.037) and BMI (partial rho = 0.229, p = 0.026). Overweight/obese women had higher leptin and total IGF-I concentrations than normal weight women (p < 0.01). The serum leptin and total IGF-I concentrations were differentially correlated with age and anthropometric and body composition variables in the two groups. Whereas in normal weight women, leptin was negatively related to BMI (partial rho = -0.356, p = 0.015), in overweight/obese women, BMI, BF%, and FM independently contributed to the serum leptin variability (partial rho = 0.370, p = 0.013; partial rho = -0.320, p = 0.034; partial rho = 0.421, p < 0.01, respectively). There was a weak association between age and total IGF-I concentration in normal weight women, which did not reach statistical significance (partial rho = -0.255, p = 0.091). None of the variables was associated with the total IGF-I in overweight/obese women (p > 0.05).

CONCLUSIONS

Although the studied anthropometric and body composition variables could explain approximately half of the leptin variance in Iranian women, they explained only a small proportion of total IGF-I variability. Our results indicated that the serum leptin and total IGF-I concentrations are differentially regulated in healthy normal weight and overweight/obese Iranian women.

Leptin and its metabolic interactions: an update

Obesity results from an abnormal accumulation of fat in the white adipose tissue. Recent research utilizing genetic models of obesity in rodents has implicated a major role of leptin as a controller of obesity. Leptin is a 167-amino acid peptide hormone encoded by the obesity gene (ob), which is secreted by adipocytes and plays an important role in regulating food intake, energy expenditure and adiposity. Leptin receptors (OB-R) are expressed in the central nervous system mainly in afferent satiety centres of hypothalamus and in peripheral organs such as adipose tissues, skeletal muscles, pancreatic beta-cells and liver, thus indicating the autocrine and paracrine role of leptin in energy regulation. In human beings, a highly organized circadian pattern of leptin secretion is observed with peak levels in the midnight probably resulting from cumulative hyperinsulinemia of entire day. Leptin has a dual role in weight maintenance. Leptin reflects total body adipose tissue mass whereas in conditions of negative and positive energy balance, the dynamic changes in plasma leptin concentration function as a sensor of energy balance and influence the efferent energy regulation pathways. Many effects of leptin on metabolism are mediated by interaction with Insulin and also by synergistic action with cholecystokinin. Besides physiological roles, leptin may influence pathological conditions like obesity-associated atherosclerosis, oxidative stress and cancers. The purpose of the present review is to summarize the important aspects of the biology, actions, and regulation of leptin and to serve as an update of new information.

Insulin and leptin relations in obesity: a multimedia approach

Obesity has been recognized as a worldwide public health problem. It significantly increases the chances of developing several diseases, including Type II diabetes. The roles of insulin and leptin in obesity involve reactions that can be better understood when they are presented step by step. The aim of this work was to design software with data from some of the most recent publications on obesity, especially those concerning the roles of insulin and leptin in this metabolic disturbance. The most notable characteristic of this software is the use of animations representing the cellular response together with the presentation of recently discovered mechanisms on the participation of insulin and leptin in processes leading to obesity. The software was field tested in the Biochemistry of Nutrition web-based course. After using the software and discussing its contents in chatrooms, students were asked to answer an evaluation survey about the whole activity and the usefulness of the software within the learning process. The teaching assistants (TA) evaluated the software as a tool to help in the teaching process. The students' and TAs' satisfaction was very evident and encouraged us to move forward with the software development and to improve the use of this kind of educational tool in biochemistry classes.

Body weight and plasma levels of ghrelin and leptin during treatment with olanzapine

Although enhanced appetite and weight gain are potential side effects of treatment with antipsychotic agents, particularly olanzapine and clozapine, the mechanisms underlying these side effects are poorly understood. Leptin and ghrelin were recently identified as hormones that play crucial roles in the regulation of energy balance and glucose metabolism. To elucidate relationships between weight change and plasma levels of ghrelin and leptin, we investigated the circulating ghrelin and leptin levels and body weight during olanzapine treatment. Twenty-four patients with schizophrenia were examined during 6-month administration of olanzapine. Ghrelin, leptin, weight and body mass index (BMI) were measured before and after 2, 4, 8, 12, 16, and 24 weeks of olanzapine treatment. The concentration of glucose and various lipid metabolic parameters were measured at baseline and at 24 weeks. Significant increases in weight, BMI and leptin were observed at week 24. On the other hand, the serum levels of ghrelin decreased significantly after olanzapine treatment. In addition, the level of ghrelin was negatively correlated with the leptin level, BMI and weight. The leptin level was positively correlated with both BMI and weight. Ghrelin is associated with metabolic changes, in combination with leptin, during olanzapine treatment. However, further large-scale and longitudinal studies are warranted to elucidate the metabolic changes involving ghrelin, leptin and insulin during treatment with antipsychotics.

Premature ejaculation and serum leptin level: a diagnostic case-control study

INTRODUCTION

Premature ejaculation (PE) is regarded as the most common male sexual disorder. To date, there is no accurate and objective diagnostic test for PE.

AIM

To determine the diagnostic value of serum leptin level for PE.

METHODS

In a case-control design, the serum leptin level of 46 PE patients referred to our outpatient clinic were determined and compared with 44 control patients referred to the same clinic with the complaint of nephrolithiasis. PE was defined based on the Diagnostic and Statistical Manual of Mental Disorders IV criteria and an intravaginal ejaculatory latency time of less than a minute.

MAIN OUTCOME MEASURES

Serum leptin level and presence of PE.

RESULTS

The PE patients had significantly higher serum leptin levels (8.3+/-3 ng/mL) than the controls (3.3+/-1 ng/mL) (P<0.001). Sensitivity and specificity for the test as a predictive diagnostic tool for PE were 80.4% and 97.7%, respectively, at the cutoff value of 6.3 ng/mL.

CONCLUSIONS

According to our results, leptin level in patients with PE was significantly higher than in the control subjects. More studies are necessary to determine the value of serum leptin as a diagnostic tool for PE.

Evaluation of Serum Ghrelin and Leptin Levels in Suicide Attempters

Previous studies have reported a relationship between cholesterol and leptin levels, and suicide attempts, impulsivity, and aggressive behaviors. An orexigenic hormone seems to be strongly associated with lipid metabolism and leptin levels. Therefore, we aimed to compare serum cholesterol, leptin, and ghrelin levels in 36 patients with suicide attempts and 25 healthy controls. Patients with suicide attempts had decreased leptin levels and significantly higher ghrelin levels compared to healthy controls. While the serum ghrelin level did not show any correlation with the demographic and clinical factors, leptin showed a correlation with body mass index (BMI), and cholesterol levels were correlated with the age, BMI, and number of suicide attempts in the suicidal group. The results suggest that suicide attempts seem to be related with higher serum ghrelin values, decreased leptin, and cholesterol levels.