Leptin, reproduction and sex steroids

Assessment of Eating Disorders and Eating Behavior to Improve Treatment Outcomes in Women with Polycystic Ovary Syndrome

The essential role of the frequent coexistence of mental disorders and polycystic ovary syndrome (PCOS) is being increasingly recognized in the management of PCOS patients since it influences the success of weight loss interventions. Patients frequently experience disrupted eating behaviors, evidenced by the high prevalence of eating disorders in this population. Therefore, assessment and potential modification of eating disorders and eating-related behavior might be especially relevant to improve obesity treatment outcomes in this population, which remains the most efficient causal treatment in PCOS patients with high metabolic risk. Following a literature overview on common eating disorders and eating behaviors in PCOS, the aim of this review was to explore the prevalence and underlying mechanisms behind those occurrences. Understanding the clinical relevance of those associations and the addition of the assessments of eating disorders as well as eating phenotypes, eating chronotypes, and eating content as essential determinants of eating behavior could aid in the successful management of women with PCOS. In addition, the review also covers the potential of using eating disorders and eating behavior as a tool for the personalization of obesity treatment in PCOS.

High Fat High Sucrose Diet Modifies Uterine Contractility and Cervical Resistance in Pregnant Rats: The Roles of Sex Hormones, Adipokines and Cytokines

Background: In obesity, the adipose tissue becomes a very significant endocrine organ producing different factors called adipokines, such as leptin, adiponectin and kisspeptin; however, no data are available about their actions on uterine contraction in obese pregnant rats. Our aim was to study the impact of obesity on pregnant uterine contraction in a rat model. Methods: Obesity was induced by the consumption of a high fat high sucrose diet (HFHSD) for 9 weeks, including pregnancy. Glucose tolerance, sex hormone, cytokine and adipokine levels were measured. Uterine contractions and cervical resistance, as well as their responses to adipokines, were tested along with the expressions of their uterine receptors. Results: HFHSD increased body weight, and altered glucose tolerance and fat composition. The uterine leptin and kisspeptin pathway affect increased. The levels of proinflammatory cytokines were reduced, while the plasma level of progesterone was increased, resulting in weaker uterine contractions, and improving the uterine relaxing effects of adipokines. HFHSD reduced cervical resistance, but the core effect of adipokines is difficult to determine. Conclusions: Obesity in pregnant rats reduces uterine contractility and cytokine-induced inflammatory processes, and therefore obese pregnant rat methods are partially applicable for modelling human processes.

Evaluating the Clinical Risk Factors Associated With Miscarriages in Women in Karachi, Pakistan

Introduction Spontaneous pregnancy loss is unquestionably common worldwide, with roughly 5% of pregnancies ending in this way. Miscarriage can lead to serious psychological issues for women as well as their mothers. Although, it is irreversible but can be prevented through proper risk assessment of women. The goal of this study is to find clinical predictors of miscarriages in Karachi, Pakistani women. Methodology The study is a retrospective chart review that used data of women having livebirth and miscarriages at the Liaquat National Hospital Karachi Pakistan. Data of a total of 517 women were included in the study, out of which 453 have had a live birth, and 64 had miscarriages. To determine the factors associated with miscarriages, multivariable logistic regression was used.  Results The mean age of women was 31.08 (±5.10) years. Age of mother over 40 years (adjusted odds ratio [AOR]=10.28; p-value=0.001), overweight and obesity (AOR=3.01; p-value=0.001) and history of miscarriage (AOR=2.91; p-value=0.003) are variables significantly associated with miscarriages. Conclusion Findings of the current study shown that risk factors of miscarriages included age of mother, increased BMI and previous history of miscarriages. All these factors need to be considered while providing antenatal care to mothers to mitigate the risk of miscarriages.

Effect of BsaA I genotyped intronic SNP of leptin gene on production and reproduction traits in Indian dairy cattle

In the present study, candidate single nucleotide polymorphism (SNP) g.92450765 G > A of leptin gene was explored for Bos indicus cattle with an aim to explore its possible effect on production and reproduction traits. The genotypic and allelic frequencies of BsaA 1 genotyped SNP g.92450765 G > A indicated the predominance of AG (0.65) genotyped Sahiwal cows in our studied population. The least-squares analysis showed a significant association (p < 0.05) of identified genetic variants with total milk yield (TMY) and 305 days milk yield (MY) (p < 0.05). The GG genotyped cows were found to be associated with higher milk yields. However, for reproduction traits under study AA genotype was found to be more favorable with respect to service period and calving interval (p < 0.05). Computational analysis was also performed to predict changes if any in the transcription factor binding sites (TFBS) caused due to the identified SNP in the intronic region of the leptin gene. TFBS analysis predicted that the targeted SNP at g.92450765G > A may lead to the disappearance of TFBS such as Hypermethylated in cancer 2 protein (HIC2), Max-binding protein MNT (MNT), Cyclic AMP-dependent transcription factor -3 (ATF3), Myc-associated factor X (MAX) and Microphthalmia-associated transcription factor (MITF). It may lead to changes in transcriptional regulation.

The Impact of Appetite-Regulating Neuropeptide Leptin on Alcohol Use, Alcohol Craving and Addictive Behavior: A Systematic Review of Preclinical and Clinical Data

AIMS

The appetite regulating hormone leptin, which is mainly secreted from adipose tissue, is an important regulator of food intake and modulator of reward-driven behavior. Leptin exerts its biological actions via binding to the leptin receptor, which is expressed in the hypothalamus, but also in the hippocampus, the amygdala and the substantia nigra. In the ventral tegmental area (VTA), leptin attenuates the firing rate of dopaminergic neurons that project to the Nucleus accumbens (NAc), which serves as relay to other brain areas of the "addiction network", such as the prefrontal cortex. This suggests that leptin plays a role in the processing of rewards in the context of substance use disorders such as alcohol use disorder, especially through attenuation of dopaminergic activity in the mesolimbic reward system. This supports the plausibility of leptin's potential effects in alcohol use disorder.

METHODS

We searched MEDLINE from 1990 to February 2020. All abstracts were screened for relevance and we only included publications reporting original data with a full text available in English language. Studies that did not report leptin-data, reviews or case reports/series were not included.

RESULTS

We identified a total of N=293 studies of whom a total of N=55 preclinical and clinical studies met the specified criteria. N=40 studies investigated the effects of alcohol on leptin plasma levels, N=9 studies investigated the effects of leptin on alcohol craving and N=6 studies investigated the effects of leptin on relapse and alcohol consumption.

CONCLUSIONS

In this review of preclinical and clinical data, we assess the role of leptin in alcohol use and the development and maintenance of an alcohol use disorder, alcohol craving and relapse. Integrating the existing preclinical and clinical data on leptin may reveal new and innovative targets for the treatment of substance use disorders in the future.

Leptin and leptin receptor genes in tongue sole (Cynoglossus semilaevis): Molecular cloning, tissue distribution and differential regulation of these genes by sex steroids

Leptin (Lep) is a key factor for the regulation of food intake and energy homeostasis in mammals. To date, a number of studies have provided evidence for the existence of multiple leptin genes in teleosts, but not much information is available in fish regarding the regulation of leptin genes by sex steriods. As a first step, two leptin genes (lepa and lepb) and a leptin receptor (lepr) gene were cloned from the half-smooth tongue sole (Cynoglossus semilaevis), a representative species of the order Pleuronectiformes. The full-length cDNAs of tongue sole lepa and lepb were 1265 bp and 1157 bp in length, encoding for proteins of 160 aa and 158 aa, respectively. The three-dimensional structures modeling of tongue sole LepA and LepB showed strong conservation of tertiary structure with other vertebrates. The full-length cDNA of tongue sole lepr was 4576 bp, encoding a protein of 1133 aa which contained all functionally important domains conserved among vertebrate LepRs. Tissue distribution analysis showed that tongue sole lepa mRNA was highly detectable in the ovary and brain, while lepb mRNA was ubiquitously expressed in various tissues. Notably, the tongue sole lepr mRNA was most abundant in the ovary. Using a primary hepatocyte culture system, we evaluated the effects of sex steroids on lep/lepr gene expression. Both 17β-estradiol (E2) and testosterone (T) inhibited hepatic lepa and lepr mRNAs without affecting lepb mRNA levels. In addition, T also suppressed growth hormone receptor 1 (ghr1), ghr2, and insulin-like growth factor 2 (igf-2) mRNA levels, and stimulated expression of igf-1 gene. On the other hand, none of these four genes were altered by E2. To the best of our knowledge, this is the first description of a direct and differential regulation of lep/lepr gene expression by sex steroids at the hepatocyte level of a flatfish, supporting that individual leptin peptide may possess different biological roles in teleosts.

Effects of androgens on the leptin system in immature male Atlantic salmon parr

Leptin modulates all levels of the reproductive endocrine axis in mammals, and in turn, both leptin and the leptin receptor are regulated by sex steroids. The aim of this study was to investigate if sex steroids regulate the leptin system also in fish. Immature one-year old male Atlantic salmon parr were implanted with Silclear capsules that were either empty or filled with 11-ketoandrostenedione (11KA) or testosterone (T) and the effects of 35-days treatment were investigated on measures of maturation, gene expression of leptin (lepa1, lepa2), leptin receptor (lepra1) and circulating plasma leptin. Both 11-KA and T stimulated the reproductive axis by increasing testes weight and up-regulated pituitary lh-β mRNA levels and for T also fsh-β. T up-regulated transcription levels of lepa1 and lepra1 in the pituitary, while 11-KA had no effect. Leptin receptor expression in the testis was unaltered by either androgen. T up-regulated lepa1 mRNA levels significantly also in the liver, but had no effect on lepa2, and 11KA did not affect hepatic gene expression of either lepa1 or lepa2. Plasma leptin levels did not differ significantly between treatments. The results indicate that androgens regulate gene expression of leptin and the leptin receptor in different tissues in fish and that the effects of leptin might be tissue specific considering plasma levels remained unaltered. Overall, the results suggest a role for leptin in fish reproduction, where sex steroids are able to regulate components of the leptin system differentially in liver and important tissues of the reproductive axis.

Neuroendocrine Regulation of Food Intake in Polycystic Ovary Syndrome

Several peripheral and central signals are involved in the sophisticated regulation of food intake. Women with polycystic ovary syndrome (PCOS) are prone to consume a diet higher in saturated fat and foods with high glycemic index and show impaired appetite regulation and measures of satiety. As a consequence, obesity, mostly of the central type, is prevalent in the syndrome and worsens the endocrine and metabolic profile of the affected patients. This review article briefly analyzes the current knowledge about the neuroendocrine mechanisms underlying the interplay between feeding behavior, obesity, and reproductive abnormalities in PCOS.

Investigating the association between prepregnancy body mass index and adverse pregnancy outcomes: a large cohort study of 536 098 Chinese pregnant women in rural China

OBJECTIVE

Unhealthy maternal weight before pregnancy increases the risk of various adverse pregnancy outcomes. We conducted a nutrition survey to provide baseline data on the prepregnant nutritional status of mothers in order to better understand the association between prepregnancy maternal body mass index (BMI) and adverse pregnancy outcomes.

DESIGN

A large, prospective, population-based cohort study.

SETTING

Data from the National Free Preconception Health Examination Project (NFPHEP) in China during 2010-2012.

PARTICIPANTS

536 098 pregnant women out of 2 120 131 were evaluated.

PRIMARY AND SECONDARY OUTCOME MEASURES

The primary adverse pregnancy outcomes included preterm birth (PTB), low birth weight (LBW), spontaneous miscarriage (SM), ectopic pregnancy (EP) and stillbirth (SB). A χ(2) test was used to compare the prevalence of each BMI category during 2010-2012. Univariable and multiple logistic regression analyses were performed to assess the association between prepregnancy BMI and various adverse pregnancy outcomes.

RESULTS

Between 2010 and 2012, the average BMI decreased from 21.31 to 21.16, while underweight prevalence increased from 10.40% to 14.14%. An age-stratified subgroup analysis indicated that the underweight prevalence increased from 13.52% to 17.02% among women aged 21-24 and from 10.72% to 13.71% among women aged 25-34. Overweight prevalence increased from 9.84% to 10.75% (25-34 years) and from 17.10% to 19.20% (35-49 years). Obesity prevalence increased from 2.17% to 2.42% and from 4% to 4.2% among women aged 25-34 and 35-49 respectively. Prepregnancy underweight was associated with PTB, LBW and SM; overweight women had an increased risk of LBW; obese women had a higher risk of LBW, SM, EP and SB.

CONCLUSIONS

While the average prepregnancy BMI decreased, the prevalence of underweight individuals in a very large population significantly increased. The abnormal prepregnancy BMIs were associated with increased risks of adverse pregnancy outcomes. Most notably, underweight prepregnant women appeared to be at a greater risk of developing adverse pregnancy outcomes in China's rural areas.

Sex steroids stimulate leptin gene expression in Atlantic salmon parr hepatocytes in vitro

In mammals, leptin plays an important role in puberty and reproduction and leptin is regulated by sex steroids. Elevated leptin levels have been associated with sexual maturation in some teleosts such as Atlantic salmon. In the present study, primary cultures of Atlantic salmon hepatocytes were used to investigate the direct effects of different sex steroids on expression of the two salmon leptin-a genes, lepa1 and lepa2. Testosterone (T) stimulated both lepa1 and lepa2 in a dose dependent manner after four days of incubation. The stimulatory effect of T on leptin expression was not prevented by co-incubation with the aromatase inhibitor fadrozole, indicating a direct androgen effect on transcription. The non-aromatizable androgen 11-ketotestosterone (11-KT), which is the main androgen in fish, was generally slightly less potent than T in stimulating lepa1 and lepa2. The strongest stimulatory response was seen for 17β-estradiol (E2). E2 treatment significantly up-regulated lepa1 and lepa2 gene expression at doses of 10nM and 1nM for each gene, respectively. Lepa1, but not lepa2, was stimulated by T and 11-KT in immature male and immature female parr, while E2 stimulated expression of both genes. The sensitivity to sex steroid stimulation differed in maturing males compared to immature. In maturing males, the androgens and E2 stimulated lepa2 but not lepa1, while in immature males, the androgens and E2 stimulated lepa1, but only E2 stimulated lepa2. The differential response of the two leptin paralogues to the sex steroids suggests differences in regulation of the two leptin genes during maturation. Altogether, these results indicate that leptin expression in Atlantic salmon hepatocytes is directly regulated at the transcriptional level by the main teleost androgens and an estrogen, and that the response might depend on the developmental stage of the fish.

Leptin exerts proliferative and anti-apoptotic effects on goose granulosa cells through the PI3K/Akt/mTOR signaling pathway

Leptin was known as a pivotal regulator for the control of food intake and energy expenditure. However, leptin has also been found to be involved in the regulation of female reproductive system through interactions with pathways in the hypothalamic-hypophyseal axis and direct action at the ovarian level. In the present study, granulosa cells from goose ovarian preovulatory (F1-F3) follicles were cultured with leptin (0, 1, 10 or 100ng/ml). The proliferative and anti-apoptotic actions of leptin in granulosa cells were revealed by CCK-8, BrdU and TUNEL assays. Quantitative real-time PCR and Western blot analyses further indicated that leptin treatment led to increased expression of cyclin D1, cyclin D2, cyclin D3 and bcl-2, and decreased expression of p21 and caspase-3. The effects were involved in the activation of the PI3K/Akt/mTOR signaling pathway, as leptin treatment enhanced the expression of PI3K, Akt1, Akt2, Raptor, mTOR, S6K and p-S6K. Moreover, blockade of the PI3K/Akt/mTOR pathway attenuated the influences of leptin on proliferation and apoptosis of granulosa cells, considering that activated factors by leptin were inhibited in the presence of either 20μM LY294002 (a PI3K inhibitor) or 10μM rapamycin (an mTOR inhibitor). In addition, leptin had a modulatory effect on the expression of its receptor at the transcriptional and translational levels, and blockade of PI3K/Akt/mTOR inhibited both basal and leptin-induced Lepr gene and protein expression. These findings suggest that leptin exerts its proliferative and anti-apoptotic effects on goose granulosa cells through the PI3K/Akt/mTOR signaling pathway via interaction with its receptor.

Increased acyl ghrelin but decreased total ghrelin and unacyl ghrelin in Chinese Han people with impaired fasting glucose combined with impaired glucose tolerance

We assessed the plasma acyl ghrelin (AG), unacyl ghrelin (UAG), and total ghrelin (TGhr) levels in Chinese adults with pre-diabetes and newly diagnosed diabetes mellitus (NDDM) after an oral glucose tolerance test (OGTT), and abdominal subcutaneous fat area and visceral fat area (VFA) were measured. Fasting AG level was increased in the impaired fasting glucose (IFG) combined with impaired glucose tolerance (IFG+IGT) and NDDM groups. AG, UAG, and TGhr levels were significantly decreased post-OGTT, and the decrements of 30-min AG, UAG, and TGhr post-OGTT were not significantly different among groups. UAG and TGhr levels did not differ significantly among the normal glucose tolerance (NGT), IFG and NDDM groups, but they decreased obviously in the IFG+IGT and impaired glucose tolerance (IGT) groups. The NDDM group had larger VFA than the NGT, IGT, and IFG+IGT groups, even after adjustment for height, it was still larger than the NGT group. The factors such as dyslipidemia and obesity which are prone to develop insulin resistance (IR) and decrease insulin sensitivity (IS) were negatively correlated with UAG and TGhr, positively with AG/UAG, while no correlations with AG. In terms of evaluating IS and IR, AG/UAG ratio may be superior in AG concentration. Our findings suggest that relative sufficiency of AG, the deficiency of TGhr and UAG are already present in IFG+IGT patients. We speculate that there is UAG resistance in severe hyperglycemia (diabetic state), which could produce elevated TGhr and UAG compared to IFG+IGT group. In the development of T2D, increase of VFA could be the initiating factor, leading elevated AG, reduced UAG, IR, decreased IS, and finally hyperglycemia.

Obesity is associated with increased seminal insulin and leptin alongside reduced fertility parameters in a controlled male cohort

BACKGROUND

Obesity appears to be associated with male reproductive dysfunction and infertility, although this has been inconsistent and inconclusive. Insulin and leptin are known mediators and modulators of the hypothalamus-pituitary-testes axis, contributing to the regulation of male reproductive potential and overall wellbeing. These hormones are also present in semen influencing sperm functions. Although abdominal obesity is closely associated with insulin resistance (hyperinsulinaemia), hyperleptinaemia and glucose dysfunction, changes in seminal plasma concentrations of insulin, leptin and glucose in obese males has not previously been investigated.

METHODS

This small case controlled study assessed serum and seminal concentrations of insulin, leptin and glucose in obese (BMI > =30; n = 23) and non-obese (BMI < 30; n = 19) males. Following a detailed medical history and examination, participants meeting the inclusion criteria were entered for data analysis. Body parameters such as BMI, waist and hip circumference and the waist hip ratio were measured. Serum and semen samples were collected and assayed for insulin, leptin and glucose. Semen samples also underwent a standard semen analysis, with sperm mitochondrial membrane potential (MMP) and DNA fragmentation (DF).

RESULTS

Obesity was associated with increased serum and seminal insulin and leptin, with no significant difference in seminal glucose. Serum and seminal concentrations of insulin and leptin were positively correlated. Furthermore, obesity was associated with decreased sperm concentration, sperm vitality and increased MMP and DF, with a non-significant impact on motility and morphology.

CONCLUSIONS

Hyperinsulinaemia and hyperleptinaemia are associated with increased seminal insulin and leptin concentrations, which may negatively impact male reproductive function in obesity. Insulin was also found to be highly concentrated in the seminal plasma of both groups. This data will contribute to the contradictive information available in the literature on the impact of obesity and male reproduction.

Inhibition of ghrelin signaling improves the reproductive phenotype of male ob/ob mouse

OBJECTIVE

To investigate whether ghrelin signaling is involved in the pathogenesis of male factor infertility induced by leptin deficiency.

DESIGN

Experimental study.

SETTING

University academic medical center.

ANIMAL(S)

Ten-week-old C57BL/6J mice and ob/ob mice.

INTERVENTION(S)

Western blotting, (quantitative) reverse transcription-polymerase chain reaction (qRT-PCR), immunohistochemistry, and in situ end labeling of fragmented DNA.

MAIN OUTCOME MEASURE(S)

Expression levels of ghrelin and its functional receptor growth hormone (GH) secretagogue receptor 1a (GHS-R1α) were examined by Western blotting and immunohistochemistry. Ob/ob mice were injected IP with specific GHS-R1α antagonist, and thereafter germ cell apoptosis and steroidogenic capability were assessed by TUNEL assay, (q) RT-PCR, and radioimmunoassay.

RESULT(S)

Expression of GHS-R1α and its endogenous ligand ghrelin was both up-regulated in ob/ob testis. Inhibition of the ghrelin pathway restored androgen synthesis, reduced germ cell apoptosis, and thereby resulted in improved sperm production in ob/ob mice.

CONCLUSION(S)

Ghrelin, as an antagonistic partner of leptin in the endocrinic/paracrine circuit, may be involved in the pathogenesis of male factor infertility induced by leptin deficiency.

Sex-Limited Genome-Wide Linkage Scan for Body Mass Index in an Unselected Sample of 933 Australian Twin Families

Genes involved in pathways regulating body weight may operate differently in men and women. To determine whether sex-limited genes influence the obesity-related phenotype body mass index (BMI), we have conducted a general non- scalar sex-limited genome-wide linkage scan using variance components analysis in Mx (Neale, 2002). BMI measurements and genotypic data were available for 2053 Australian female and male adult twins and their siblings from 933 families. Clinical measures of BMI were available for 64.4% of these individuals, while only self-reported measures were available for the remaining participants. The mean age of participants was 39.0 years of age (SD 12.1 years). The use of a sex-limited linkage model identified areas on the genome where quantitative trait loci (QTL) effects differ between the sexes, particularly on chromosome 8 and 20, providing us with evidence that some of the genes responsible for BMI may have different effects in men and women. Our highest linkage peak was observed at 12q24 (–log10p = 3.02), which was near the recommended threshold for suggestive linkage (–log10p = 3.13). Previous studies have found evidence for a quantitative trait locus on 12q24 affecting BMI in a wide range of populations, and candidate genes for non- insulin-dependent diabetes mellitus, a consequence of obesity, have also been mapped to this region. We also identified many peaks near a –log10p of 2 (threshold for replicating an existing finding) in many areas across the genome that are within regions previously identified by other studies, as well as in locations that harbor genes known to influence weight regulation.

Androgens and adipose tissue in males: a complex and reciprocal interplay

Clinical evidence shows that in males obesity is frequently associated with hypogonadism and vice versa; also, low testosterone levels have been considered a "hallmark" of metabolic syndrome in men. These observations indicate that there is a strict connection between anatomically and functionally distinct cell types such as white adipocytes and Leydig cells, that synthesize testosterone. Adipose tissue is able to control several functions of the testis through its products secreted in the bloodstream. On the other hand, circulating levels of testosterone and estradiol deeply affect adipocyte proliferation, differentiation, and fat mass distribution, hereby controlling critical metabolic functions, such as food intake, insulin sensitivity, vascular reactivity, and immunity. This paper highlights the existing clinical and experimental evidence linking androgens and adipose tissue and illustrates the consequences occurring when the balance between fat mass distribution and eugonadism is lost.

The G3057A LEPR polymorphism is associated with obesity in Tunisian women

OBJECTIVES

The aim of this study was to evaluate the effect of the G3057A (rs62589000) LEPR polymorphism on obesity risk and plasma leptin, insulin, and lipid levels in a sample of the Tunisian population.

DESIGN AND METHODS

Three hundred and ninety-three obese patients and 317 controls participated in this study. The G3057A genotype was determined by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) analysis.

RESULTS

In the entire study sample, no significant differences in genotype frequencies were observed between obese patients and controls. However, stratified analysis by gender revealed a quantitative increase in the variant allele (33.3% vs. 25.8%; χ(2)=4.90, p=0.026) in obese women (but not men) compared to controls. When a dominant model of inheritance was assumed, the GA+AA genotypes were more prevalent in these obese female patients than in controls (58.3% vs. 47.8%; χ(2)=4.08, p=0.044). Unconditional logistic regression showed that in women only, obesity risk was significantly higher for homozygotes for the variant allele (OR=2.73, 95% CI 1.03-7.21) and for carriers of GA+AA genotypes (OR=1.53, 95% CI 1.01-2.31) compared with homozygotes for the normal allele. The association between the G3057A LEPR variant and obesity remained statistically significant even after adjustment for age. No relationship was found between the G3057A LEPR polymorphism and leptin and insulin levels. Additionally, this LEPR gene variant had no effect on plasma lipid concentrations.

CONCLUSION

There is evidence in this study that the G3057A LEPR polymorphism is associated with obesity in Tunisian women.

Polymorphisms of the LEP, LEPR and HTR2C gene: obesity and BMI change in patients using antipsychotic medication in a naturalistic setting

Weight gain is a frequently occurring serious somatic adverse effect of atypical antipsychotic agents. Genetic factors influence the risk of an individual to gain weight.

OBJECTIVES

To determine whether LEPR Q223R, LEP -2548G/A and HTR2C -759C/T polymorphisms are associated with obesity and weight change in patients using atypical antipsychotic drugs.

METHODS

A longitudinal study design was used in a naturalistic setting. The study population included 141 patients, all of whom were using an atypical antipsychotic drug. The body mass index was measured twice. Primary outcome measures were obesity at the moment of first measurement and body mass index change during treatment. Determinants were the LEPR Q223R (rs1137101), the LEP -2548G/A SNP (rs7799039) and the HTR2C -759C/T (rs3813929) polymorphisms.

RESULTS

Of the 141 included patients, 35 (24.8%) were obese. In females, presence of the LEPR 223R allele was associated with an increased risk of obesity (47.6 vs 17.6%; p = 0.03). In males this association was not found. None of the SNPs were significantly associated with weight change during treatment.

CONCLUSIONS

The LEPR Q223R polymorphism may be a risk factor for obesity in women with a psychotic disorder treated with atypical antipsychotic drugs. This is in line with earlier findings of our group.

Maternal zinc deficiency in rats affects growth and glucose metabolism in the offspring by inducing insulin resistance postnatally

Interactions among zinc (Zn), insulin, and glucose metabolism are complex. Maternal Zn deficiency affects maternal carbohydrate metabolism, but the mechanisms underlying changes in glucose homeostasis of offspring are not well understood. Rats consumed Zn-deficient (ZnD; 7 microg/g) or control (ZnC; 25 microg/g) diets ad libitum from 3 wk preconception to 21 d postparturition. Litters were culled to 7 pups/dam postnatally and pups were allowed to nurse their original mothers; after weaning, pups were fed nonpurified diet. Insulin and glucose tolerance tests were performed on the pups at wk 5 and 10. Although there was no difference in birth weight between groups, ZnD pups weighed significantly more than controls by d 10 (+5%) and 20 (+10%). Both blood glucose and serum insulin-like growth factor (IGF-1) concentrations at wk 3 were significantly higher in ZnD pups than in controls. Both male and female ZnD rats were less sensitive to insulin and glucose stimulation than controls at wk 5 and 10. At wk 15, serum leptin concentrations were higher in male ZnD rats than in controls. Phosphorylation of muscle Akt protein, an insulin receptor (IR) signaling intermediate, was lower in female ZnD rats than in controls at wk 15, but they did not differ in phosphorylation of IR. Maternal Zn deficiency resulted in greater serum IGF-1 concentrations and the excessive postnatal weight gain in their offspring as well as impaired subsequent glucose sensitivity. It was associated with gender-specific alterations in the serum leptin concentration and the insulin signaling pathway. These findings suggest that suboptimal maternal Zn status induces long-term changes in the offspring related to abnormal glucose tolerance.

Leptin as a potential therapeutic target for breast cancer prevention and treatment

IMPORTANCE OF THE FIELD

Obesity is considered to be an important risk factor for postmenopausal breast cancer. Elevated estrogen levels are thought to be a growth factor associated with this relationship. However, there is increasing evidence that factors produced directly in adipose tissue, adipokines, can also affect breast cancer development. Leptin is one of the adipokines that is measured in serum/plasma in increasing amounts as body weight/body fat increases.

AREAS COVERED IN THIS REVIEW

We highlight important aspects of leptin in relationship to mammary/breast tumor development. This includes findings from human, in vitro and animal studies. Information on leptin-related compounds which may have therapeutic use is presented. Additionally strategies to alter serum leptin levels by dietary and pharmacological interventions are discussed.

WHAT THE READER WILL GAIN

The reader will gain insights into the relationship of an adipose tissue protein and its potential role in breast cancer development as well as ways to intervene in leptin's actions.

TAKE HOME MESSAGE

Continued research will determine if interfering with the action of leptin has preventive or therapeutic applications in breast cancer.

Association of serum levels of retinol-binding protein 4 with male sex but not with insulin resistance in obese patients

BACKGROUND

Retinol-binding protein 4 (RBP4) is secreted by adipocytes and by the liver and modulates insulin sensitivity in animal models. However, controversial data exist regarding the association of serum levels of RBP4 with insulin resistance in humans. Obesity confers a major risk to develop insulin resistance.

AIM

Therefore, we investigated RBP4 levels in non-diabetic obese patients and analysed the association with insulin sensitivity and other metabolic markers.

SUBJECTS AND METHODS

Glucose tolerance was assessed by oral glucose tolerance tests and 70 normal glucose tolerant patients (36 women, 34 men; body mass index >30 kg/m(2)) were included in our study. We compared the serum level of RBP4 (measured by ELISA) with clinical features (age, sex, BMI, waist-to-hip-ratio, blood pressure) and laboratory findings (total cholesterol, triglycerides, fasting glucose, 2-hour glucose, fasting insulin, HOMA-IR and HOMA-B). The associations between RBP4 and the above mentioned variables were assessed using multiple linear regression models.

RESULTS

The mean age (+/-SD) of the subjects included was 48.1 (+/- 12.3) years and the mean BMI 41.6 (+/- 7.4) kg/m(2). We found significantly higher RBP4 levels in men (53.0 +/- 20.8 microg/ml) than in women (39.7 +/- 12.3 microg/ml) (p = 0.0013). However, age and sex-adjusted multiple linear regression models showed no significant association of serum RBP4 levels with BMI, waist-to-hip-ratio, blood pressure, cholesterol, triglycerides, fasting glucose, 2-hour glucose, insulin resistance (as assessed by HOMA-IR), or insulin secretion (as assessed by HOMA-B).

CONCLUSION

Our data show higher RBP4 levels in obese men than in obese women. However, there was no association of RBP4 levels with insulin resistance or other components of the metabolic syndrome. We conclude that obesity might already be associated with elevated RBP4 levels which then show no additional correlation with metabolic markers.

Polymorphisms of the LEP- and LEPR gene and obesity in patients using antipsychotic medication

Weight gain is one of the most serious adverse effects of atypical antipsychotic agents. Genetic factors influence the risk of an individual to gain weight. The objective of our study was to determine whether the LEPR Q223R polymorphism and the LEP promoter 2548G/A polymorphism are associated with obesity in a group of male and female patients using atypical antipsychotic drugs. A cross-sectional study design was used. The study population consisted of 200 patients aged between 18 and 65 years, diagnosed with a psychotic disorder, all of whom had been using an atypical antipsychotic for at least 3 months. The primary outcome measure was the presence of obesity. Determinants were the LEPR Q223R (rs1137101) polymorphism and the LEP promoter 2548G/A single nucleotide polymorphism ([SNP] rs7799039). Of the 200 included patients, 61 (31%) were obese. In females, the LEPR 223QR (adjusted odds ratio, 0.11; 95% confidence interval [CI], 0.02-0.54) and LEPR 223RR (adjusted odds ratio, 0.07; 95% CI, 0.01-0.63) genotypes were associated with a lower risk of obesity. In males, this association was not found. In females, the average body weight was 13.6 kg more (95% CI, 1.11-26.1) in the LEPR 223QQ group compared with the LEPR 223RR group. No significant association was found between the LEP promoter 2548G/A polymorphism and obesity. Taken together, the results of our study show that the LEPR Q223R polymorphism may be associated with obesity in women with a psychotic disorder treated with atypical antipsychotic drugs and stress the importance of stratification for gender when investigating the role of variations of the LEP- and LEPR genes on the metabolic side effects of antipsychotic medications.

Early risk factors for miscarriage: a prospective cohort study in pregnant women

Many pregnancies are lost during early gestation, but clinicians still lack tools to recognize risk factors for miscarriage. Thus, the identification of risk factors for miscarriage during the first trimester in women with no obvious risk for a pregnancy loss was the aim of this prospective cohort trial. A total of 1098 women between gestation weeks 4 and 12 in whom no apparent signs of a threatened pregnancy could be diagnosed were recruited. Demographic, anamnestic, psychometric and biological data were documented at recruitment and pregnancy outcomes were registered subsequently. Among the cases with sufficiently available data, 809 successfully progressing pregnancies and 55 subsequent miscarriages were reported. In this cohort, risk of miscarriage was significantly increased in women at higher age (>33 years), lower body mass index (< or =20 kg/ m(2)) and lower serum progesterone concentrations (< or =12 ng/ml) prior to the onset of the miscarriage. Women with subsequent miscarriage also perceived higher levels of stress/demands (supported by higher concentrations of corticotrophin-releasing hormone) and revealed reduced concentrations of progesterone-induced blocking factor. These risk factors were even more pronounced in the subcohort of women (n = 335) recruited between gestation weeks 4 and 7. The identification of these risk factors and development of an interaction model of these factors, as introduced in this article, will help clinicians to recognize pregnant women who require extra monitoring and who might benefit from therapeutic interventions such as progestogen supplementation, especially during the first weeks of pregnancy, to prevent a miscarriage.

Role of neuropeptides in appetite regulation and obesity--a review

Obesity represents the most prevalent nutritional problem worldwide which in the long run predisposes to development of diabetes mellitus, hypertension, endometrial carcinoma, osteoarthritis, gall stones and cardiovascular diseases. Despite significant reductions in dietary fat consumption, the prevalence of obesity is on a rise and is taking on pandemic proportions. Obesity develops when energy intake exceeds energy expenditure over time. Recently, a close evolutionary relationship between the peripheral and hypothalamic neuropeptides has become apparent. The hypothalamus being the central feeding organ mediates regulation of short-term and long-term dietary intake via synthesis of various orexigenic and anorectic neuropeptides. The structure and function of many hypothalamic peptides (neuropeptide Y (NPY), melanocortins, agouti-related peptide (AGRP), cocaine and amphetamine regulated transcript (CART), melanin concentrating hormone (MCH), orexins have been characterized in rodent models The peripheral neuropeptides such as cholecystokinin (CCK), ghrelin, peptide YY (PYY3-36), amylin, bombesin regulate important gastrointestinal functions such as motility, secretion, absorption, provide feedback to the central nervous system on availability of nutrients and may play a part in regulating food intake. The pharmacological potential of several endogenous peripheral peptides released prior to, during and/or after feeding are being explored. Long-term regulation is provided by the main circulating hormones leptin and insulin. These systems implicated in hypothalamic appetite regulation provide potential targets for treatment of obesity which could potentially pass into clinical development in the next 5 years. This review summarizes various effects and interrelationship of these central and peripheral neuropeptides in metabolism, obesity and their potential role as targets for treatment of obesity.

Role of androgens and glucocorticoids in the regulation of diazepam-binding inhibitor mRNA levels in male mouse hypothalamus

In peripheral organs, gonadal and adrenal steroids regulate diazepam-binding inhibitor (DBI) mRNA expression. In order to further investigate the involvement of peripheral steroid hormones in the modulation of brain DBI mRNA expression, we studied by semiquantitative in situ hybridization the effect of adrenalectomy (ADX) and castration (CX) and short-term replacement therapy on DBI mRNA levels in the male mouse hypothalamus. Cells expressing DBI mRNA were mostly observed in the arcuate nucleus, the median eminence and the ependyma bordering the third ventricle. In the median eminence and the ependyma bordering the third ventricule, the DBI gene expression was decreased in ADX rats and a single injection of corticosterone to ADX rats induced a significant increase in DBI gene expression at 3 and 12 h time intervals without completely restoring the basal DBI mRNA expression observed in intact mice. In the arcuate nucleus, ADX and corticosterone administration did not modify DBI mRNA expression. CX down-regulated DBI gene expression in the ependyma bordering the third ventricle. The administration of dihydrotestosterone (3-24 h) completely reversed the inhibitory effect of CX. In the median eminence and arcuate nucleus, neither CX or dihydrotestosterone administration modified DBI mRNA levels. These results suggest that the effects of glucocorticoids on the hypothalamo-pituitary-adrenocortical axis and androgens on the hypothalamo-pituitary-gonadal axis are mediated by DBI.

Normative data for adiponectin, resistin, interleukin 6, and leptin/receptor ratio in a healthy Spanish pediatric population: relationship with sex steroids

OBJECTIVES

To investigate the circulating levels of adiponectin, resistin, interleukin 6 (IL-6), and leptin/receptor ratio in healthy Spanish children throughout the different stages of pubertal development. To analyze the relationship between adipokines and sex steroid level changes during puberty.

STUDY DESIGN

Serum adiponectin, resistin, IL-6 levels, and leptin/receptor ratio were studied in 160 healthy Spanish children grouped according to their pubertal stage (Tanner I, 23 girls and 22 boys; Tanner II, 19 girls and 16 boys; Tanners III and IV, 21 girls and 20 boys; and Tanner V, 20 girls and 19 boys). In addition, circulating levels of sex hormone-binding globulin (SHBG) were determined in every subject, and testosterone and estradiol levels in boys and girls respectively.

RESULTS

Adiponectin levels decreased in boys from mid puberty (P < 0.05) to become significantly lower than in girls (P < 0.001), whereas IL-6 decreased in both sexes (P < 0.05). Resistin levels and leptin/receptor ratio showed no differences between sexes or according to pubertal stage, except in adult females, who had the highest levels of both parameters (P < 0.001). Serum IL-6 levels correlated significantly (P < 0.05) with testosterone and estradiol levels (r=-0.37 and -0.42 respectively), whereas estradiol, but not testosterone, correlated with leptin/receptor ratio (r=0.59; P < 0.001). Furthermore, a positive relationship was found between SHBG and adiponectin and IL-6 (P < 0.001 and P < 0.05 respectively). In addition, a direct correlation between leptin/receptor and body mass index was found in both sexes (P < 0.001).

CONCLUSION

Variations in adipokine profiles throughout pubertal development appear to be related with progression of gonadal function.

Leptin in pregnancy: an update

Leptin influences satiety, adiposity, and metabolism and is associated with mechanisms regulating puberty onset, fertility, and pregnancy in various species. Maternal hyperleptinemia is a hallmark of mammalian pregnancy, although both the roles of leptin and the mechanisms regulating its synthesis appear to be taxa specific. In pregnant humans and nonhuman primates, leptin is produced by both maternal and fetal adipose tissues, as well as by the placental trophoblast. Specific receptors in the uterine endometrium, trophoblast, and fetus facilitate direct effects of the polypeptide on implantation, placental endocrine function, and conceptus development. A soluble isoform of the receptor may be responsible for inducing maternal leptin resistance during pregnancy and/or may facilitate the transplacental passage of leptin for the purpose of directly regulating fetal development. The steroid hormones are linked to the regulation of leptin and the leptin receptor and probably interact with other pregnancy-specific, serum-borne factors to regulate leptin dynamics during pregnancy. In addition to its effects on normal conceptus development, leptin is linked to mechanisms affecting a diverse array of pregnancy-specific pathologies that include preeclampsia, gestational diabetes, and intrauterine growth restriction. Association with these anomalies and with mechanisms pointing to a fetal origin for a range of conditions affecting the individual's health in adult life, such as obesity, diabetes mellitus, and cardiovascular disease, reiterate the need for continued research dedicated to elucidating leptin's roles and regulation throughout gestation.

Correlation of apolipoprotein M with leptin and cholesterol in normal and obese subjects

Apolipoprotein M (apoM) is a recently characterized apolipoprotein that is exclusively expressed in the liver and kidney. In plasma it is present predominantly in high-density lipoprotein (HDL). The physiological function of apoM is not yet known. In the present study we investigated relationships between plasma apoM levels and leptin levels, body mass index (BMI), as well as fasting glucose and other lipid parameters in women with a wide range of BMI (18.9-57.1 kg/m(2), n = 51). In univariate analysis, apoM correlated significantly with leptin (r = 0.54, P < 0.001), BMI (r = 0,70, P < 0.001), fasting insulin (r = 0.33, P = 0.025), total cholesterol (r = -0.41, P = 0.016), and LDL-cholesterol (r = -0.39, P = 0.018). The correlations between apoM and cholesterol and between apoM and leptin remained significant after adjustment for the influence of BMI. Forward stepwise multiple regressions when leptin, BMI, insulin, and cholesterol were entered into a model as independent variables and apoM as the dependent variable, showed that cholesterol and leptin were independent predictors of circulating apoM. These two parameters yielded a value of r(2) = 0.28, thereby explaining approximately 30% of the variance in apoM. Hence, we show that apoM is positively related to leptin and negatively related to cholesterol in humans.

Both leptin and leptin-receptor are essential for apolipoprotein M expression in vivo

It was previously shown that circulating levels of leptin and apolipoprotein M (apoM) correlate to each other. In this study, we examined whether plasma leptin and leptin-receptors are of importance for apoM expression in vivo. It was found that in both liver and kidney, expression of apoM was significantly lower in leptin deficient ob/ob mice and in leptin-receptor deficient db/db mice than in control mice. Furthermore, leptin administration (0.5 or 1.5 microg/g body weight) significantly increased plasma apoM levels and apoM mRNA levels in liver and in kidney in ob/ob mice. We conclude that both leptin and leptin-receptor are essential for the apoM expression, indicating that leptin is physiologically regulating apoM synthesis in vivo.

Soluble leptin receptor and leptin levels in pregnant women before and after delivery

Soluble leptin receptor is an extracellular domain of the leptin receptor that serves as the main leptin-binding protein and may play a role in the regulation of leptin tissue effects. The aim of our study was to assess serum concentrations of leptin, soluble leptin receptor, and other hormones involved in the regulation of leptin secretion in pregnant women before and after delivery. Serum leptin, cortisol, and tumor necrosis factor alpha (TNF-alpha) concentrations in 19 pregnant women before delivery were significantly higher than in healthy nonpregnant women (33.3+/-21.0 vs. 7.9+/-3.5 ng/mL, 1068.9+/-442.2 vs. 546.6+/-165.3 nmol/L, 4.4+/-1.1 vs. 3.4+/-1.2 ng/mL, respectively). In contrast, no differences between these groups were found in soluble leptin receptor levels. Delivery significantly decreased serum leptin and cortisol levels and increased soluble leptin receptor levels (12.3+/-9.1 ng/mL, 749.6+/-205.3 nmol/L, 23.3+/-7.9 U/mL, respectively). Soluble leptin receptor levels after delivery became higher than in the control group. We conclude that serum leptin and serum soluble leptin-receptor levels are significantly affected by pregnancy and delivery. The regulation of leptin levels in this group of patients appears to be distinct and independent of soluble leptin-receptor levels.

Leptin receptor expression in fetal lung increases in late gestation in the baboon: a model for human pregnancy

Leptin produced by both adipose tissue and the placental trophoblast, has been proposed to regulate numerous aspects of human conceptus development. Although recent animal studies have suggested an additional role for the polypeptide in fetal lung maturation, no evidence has been reported in primates. Therefore, we employed the baboon (Papio sp.), a well-characterized primate model for human pregnancy, to determine the presence and ontogeny of leptin receptor in fetal lung with advancing gestation. Lungs were collected from fetal baboons, early in gestation (days 58-62, n = 4), at mid gestation (days 98-102, n = 4), and late in gestation (days 158-165, n = 4) (term 184 days). mRNA transcripts for leptin (LEP) and both long and short intracellular domain isoforms of the leptin receptor (LEP-R(L) and LEP-R(S)) were assessed by RT-PCR. leptin receptor protein was evaluated by immunoblotting and cell types expressing leptin receptor were identified in late pregnancy by immunohistochemistry. Fetal serum leptin concentrations, determined by RIA, remained relatively unchanged at 5.7 +/- 1.1 ng/ml (mean +/- s.e.m.) in mid pregnancy and 8.4 +/- 3.0 ng/ml in late pregnancy (P > 0.05). Although leptin were detectable in fetal lung, no changes in transcript abundance were apparent with advancing gestation. However, transcripts for both LEP-R(L) and LEP-R(S) receptor isoforms increased several-fold (P < 0.05) in fetal lung between mid and late gestation, while leptin receptor protein was detectable only in late pregnancy. leptin receptor was localized in distal pulmonary epithelial cells, including type II pneumocytes. In conclusion, leptin is present in the fetal baboon and its receptor is enhanced during late gestation in cells responsible for the synthesis of pulmonary surfactant. Collectively, these and past findings may suggest a modulatory role for the polypeptide in pulmonary development and/or may identify leptin receptor as a physiological marker of primate fetal lung maturity.

Ghrelin secretion is modulated in a nutrient- and gender-specific manner

BACKGROUND

Ghrelin is a potent GH secretagogue that also plays an important role in appetite and weight regulation. Ghrelin increases hunger and food intake, and its levels decrease after a standard meal or glucose.

OBJECTIVE

To examine the effects of standard oral glucose, lipid and protein loads on ghrelin levels, investigating the possibility that these responses may be modulated by several anthropometric and metabolic factors.

SUBJECTS AND METHODS

There were 24 adult nondiabetic subjects (13 men/11 women; mean age 55.3 +/- 2.9 years, range 26-74 years). Each participant underwent one or more of the following nutrient loads: (i) a standard oral glucose (75 g) load (n = 18); (ii) an oral lipid load (40 g, with 24 g saturated fat; n = 13); (iii) an oral protein load (40 g; n = 11).

RESULTS

Fasting ghrelin levels were negatively related to body mass index (BMI; r =-0.47; P = 0.02), waist circumference (r = -0.58; P = 0.0028), waist/hip ratio (r = -0.56; P = 0.0046), fasting insulin (r = -0.44, P = 0.03), and homeostasis model assessment insulin resistance index (HOMA-R; r = -0.43, P = 0.034). Glucose load induced a decrease in ghrelin levels (P < 0.0001), and this response was modulated by sex (P < 0.0001), in that levels were significantly higher in females. The presence of obesity affected ghrelin response to glucose (< 0.0217), in that log-transformed ghrelin levels started to increase back to baseline after its initial decline earlier in obese than in lean subjects. Ghrelin levels after a glucose load were lower over time in subjects with more pronounced insulin resistance (P < 0.0001). Similarly, ghrelin levels decreased significantly following the lipid meal (P = 0.035), and were modulated by HOMA-R (P = 0.027) and gender (P = 0.029). Protein did not affect ghrelin levels.

CONCLUSIONS

This study demonstrates that ghrelin levels respond in a different manner to glucose, lipid and protein loads, and are subject to modulation according to gender, obesity and insulin sensitivity.

Percent body fat at age 5 predicts earlier pubertal development among girls at age 9

OBJECTIVE

This study examines the causal direction of the relationship between weight status and pubertal timing in girls using a longitudinal sample of 183 white girls followed from ages 5 to 9.

METHODS

Girls' weight status (body mass index percentile, percent body fat, waist circumference) was assessed when they were 5, 7, and 9 years old, and their pubertal development was assessed when they were 9 years old (breast development, Estradiol, Pubertal Development Scale). Information from all measures of pubertal development at 9 years was combined to identify girls exhibiting earlier (N = 44) and later (N = 136) pubertal development relative to the sample. Girls' weight status at each age (5, 7, and 9 years old) and change in weight status across the ages of 5 to 9 years were used to predict their pubertal timing at 9 years of age.

RESULTS

Girls with higher percent body fat at 5 years, and girls with higher percent body fat, higher BMI percentile, or larger waist circumference at 7 years, were more likely to be classified with earlier pubertal development at 9 years. In addition, girls showing larger increases in percent body fat from 5 to 9 years of age, and larger increases in waist circumference from 7 to 9 years of age, were more likely to exhibit earlier pubertal development at 9 years. Results were still present after controlling for accelerated growth.

CONCLUSIONS

Girls with higher weight status in early childhood were more likely to exhibit earlier pubertal development relative to peers at 9 years, indicating that weight status preceded pubertal timing in girls.

Both fasting-induced leptin reduction and GH increase are blunted in Cushing's syndrome and in simple obesity

BACKGROUND

Simple obesity and Cushing's syndrome (CS) are two clinical models of leptin hypersecretion coupled with GH hyposecretion. Fasting inhibits leptin while stimulating GH secretion in normal human subjects.

OBJECTIVES

To clarify the effect of fasting on leptin and GH secretion in obesity and CS. PATIENTS AND PROTOCOL: We studied six women with CS [age 17-66 years; body mass index (BMI) 28.6 kg/m2], seven women with visceral obesity (OB; 20-41 years; BMI 42.9 kg/m2) and seven normal women (NS; 25-31 years; BMI 19.3 kg/m2). The effects of 36-h fasting on 8-h diurnal mean leptin, GH, insulin and glucose concentrations (mLEPTc, mGHc, mINSc and mGLUc) as well as on the IGF/IGFBP system were studied.

RESULTS

Before fasting, mLEPTc in OB and in CS were similar and both were higher (P < 0.01) than in NS. OB and CS showed similar mGHc, which were lower (P < 0.05) than in NS. Fasting induced a reduction in mLEPTc that was significant in NS and CS (P < 0.04) but not in OB. The mLEPTc in OB and CS after fasting remained higher (P < 0.05) than in NS. After fasting, OB and CS showed no increase in mGHc, although this clearly increased (P < 0.02) in NS. IGF-I but not IGFBP-3 levels decreased in all groups (P < 0.05). Fasting reduced mINSc and mGLUc while increasing IGFBP-1 in all groups. After fasting, mINSc in OB and CS remained higher (P < 0.03) than in NS.

CONCLUSIONS

Short-term fasting has less inhibitory effect on leptin and no stimulatory effect on GH secretion in patients with Cushing's syndrome as well as simple obesity. After fasting, insulin levels in hypercortisolaemic and also in obese patients remained higher than in normal subjects suggesting that hyperinsulinism could play a role in the altered response of leptin and GH to starvation in these conditions.