Nonadipose tissue production of leptin: leptin as a novel placenta-derived hormone in humans

Cord blood leptin DNA methylation levels are associated with macrosomia during normal pregnancy

BACKGROUND

We previously demonstrated an association between placental leptin (LEP) methylation levels and macrosomia without gestational diabetes mellitus (non-GDM). This study further explored the association between LEP methylation in cord blood and non-GDM macrosomia.

METHOD

We carried out a case-control study of 61 newborns with macrosomia (birth weight ≥4000 g) and 69 newborns with normal birth weight (2500-3999 g). Methylation in the LEP promoter region was mapped by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry.

RESULTS

Average cord blood LEP methylation levels were lower in macrosomia newborns than in control newborns (P < 0.001). Eleven CpG sites were associated with macrosomia. Multivariate logistic regression revealed that low LEP methylation levels [adjusted odds ratio (AOR) = 2.84, 95% confidence interval (CI): 1.72-4.17], high pre-pregnancy body mass index (AOR = 7.44, 95% CI: 1.99-27.75), long gestational age (AOR = 3.18, 95% CI: 1.74-5.79), high cord blood LEP concentration (AOR = 2.25, 95% CI: 1.34-3.77), and male newborn gender (AOR = 3.91, 95% CI: 1.31-11.69) significantly increased the risk of macrosomia.

CONCLUSIONS

Lower cord blood LEP methylation levels and certain maternal and fetal factors are associated with non-GDM macrosomia.

Organokines in disease

Studies have linked obesity, metabolic syndrome, type 2 diabetes, cardiovascular disease (CVD), nonalcoholic fatty liver disease (NAFLD) and dementia. Their relationship to the incidence and progression of these disease states suggests an interconnected pathogenesis involving chronic low-grade inflammation and oxidative stress. Metabolic syndrome represents comorbidities of central obesity, insulin resistance, dyslipidemia, hypertension and hyperglycemia associated with increased risk of type 2 diabetes, NAFLD, atherosclerotic CVD and neurodegenerative disease. As the socioeconomic burden for these diseases has grown signficantly with an increasing elderly population, new and alternative pharmacologic solutions for these cardiometabolic diseases are required. Adipose tissue, skeletal muscle and liver are central endocrine organs that regulate inflammation, energy and metabolic homeostasis, and the neuroendocrine axis through synthesis and secretion of adipokines, myokines, and hepatokines, respectively. These organokines affect each other and communicate through various endocrine, paracrine and autocrine pathways. The ultimate goal of this review is to provide a comprehensive understanding of organ crosstalk. This will include the roles of novel organokines in normal physiologic regulation and their pathophysiological effect in obesity, metabolic syndrome, type 2 diabetes, CVD, NAFLD and neurodegenerative disorders.

[Research progress in adipose tissue promoted wound healing]

OBJECTIVE

To summarize recent progress in adipose tissue acting as a more efficient and ideal therapy to facilitate wound repair and evaluate the therapeutic values of adipose tissue.

METHODS

The related literature about adipose tissue for wound healing in recent years was reviewed and analyzed.

RESULTS

Enormous studies focus on the capacity of adipose tissue to accelerate wound healing including cellular components, extracellular matrix, and paracrine signaling have been investigated.

CONCLUSION

Adipose tissue has generated great interest in recent years because of unique advantages such as abundant and accessible source, thriven potential to enhance the regeneration and repair of damaged tissue. However, there is still a need to explore the mechanism that adipose tissue regulates cellular function and tissue regeneration in order to facilitate clinical application of adipose tissue in wound healing.

Altered expression of leptin and leptin receptor in the development of immune-mediated aplastic anemia in mice

The current study aimed to explore the levels of leptin (LEP) and LEP receptor (LEP-R) on the progression of aplastic anemia (AA) with bone marrow fat conversion. An AA model was developed by infusing C57BL/6 lymph node cells into BALB/c mice. At 0, 3, 6, 9, 12, 15 and 18 days after modeling, routine blood counts, bone marrow biopsy slides, lymphocyte subsets (CD4⁺ and CD8⁺ T cells) and cytokine levels [including interleukin (IL)-2, IL-4, IL-5 and interferon-γ] were assessed. LEP and LEP-R levels in peripheral blood serum, mesenchymal stem cells (MSCs) and bone marrow were also analyzed by enzyme-linked immunosorbent assay, polymerase chain reaction and immunohistochemistry. The relevance of LEP, LEP-R and other factors was analyzed by Pearson's correlation analysis. Peripheral pancytopenia (reduced count of white blood cells, red blood cells, hemoglobin and platelets), abnormal immune factor levels and histological changes in bone marrow sections were detected in the AA model mice, suggesting that these mice mimicked the pathological changes commonly observed in AA. In addition, following the establishment of AA, the LEP level was gradually increased and the LEP-R level was reduced in the mice over time (P<0.05). The expression of adipogenic genes, including CCAAT/enhancer-binding protein (C/EBP)α, C/EBPβ and peroxisome proliferator-activated receptor γ, was markedly increased, while the expression of the osteogenic gene runt-related transcription factor 2 was reduced compared with the levels in the control group (P<0.05). Taken together, damage to LEP-R may lead to dysregulation of LEP and the enhancement of MSCs to differentiate into adipocytes, resulting in excessive fat in bone marrow of AA patients.

Gastric Leptin and Tumorigenesis: Beyond Obesity

Leptin, an adipocyte-derived hormone and its receptor (ObR) expressed in the hypothalamus are well known as an essential regulator of appetite and energy expenditure. Obesity induces abundant leptin production, however, reduced sensitivity to leptin leads to the development of metabolic disorders, so called leptin resistance. The stomach has been identified as an organ that simultaneously expresses leptin and ObR. Accumulating evidence has shown gastric leptin to perform diverse functions, such as those in nutrient absorption and carcinogenesis in the gastrointestinal system, independent of its well-known role in appetite regulation and obesity. Overexpression of leptin and phosphorylated ObR is implicated in gastric cancer in humans and in murine model, and diet-induced obesity causes precancerous lesions in the stomach in mice. While the underlying pathomechanisms remain unclear, leptin signaling can affect gastric mucosal milieu. In this review, we focus on the significant role of the gastric leptin signaling in neoplasia and tumorigenesis in stomach in the context of hereditary and diet-induced obesity.

Effect of gestational weight gain on insulin resistance mediated by serum adipokine concentrations in advanced maternal age

INTRODUCTION

With the implementation of the universal two-child policy, the number of pregnant women of advanced maternal age (AMA) will increase steadily. We aimed to investigate whether the effect of gestational weight gain on insulin resistance (IR) before delivery was mediated by serum adipokine concentrations in AMA.

MATERIAL AND METHODS

This cross-sectional study included 80 pregnant women of AMA recruited consecutively before delivery from the Department of Obstetrics and Gynecology between August 2016 and July 2017. At delivery, maternal weight during the third trimester was recorded and serum adipokines were measured. IR was calculated using the homeostasis model assessment 2 (HOMA2) method.

RESULTS

Weight gain (WG) during the third trimester was positively associated with serum leptin concentrations (r = 0.34, p = 0.0018) and HOMA-IR indices (r = 0.25, p = 0.025), but not related with serum concentration of adiponectin (r = 0.12, p = 0.28). WG during the third trimester and serum concentration of leptin were independently associated with the level of HOMA-IR by multivariate analysis. Subsequently, according to mediation analysis, the association between WG during the third trimester and HOMA-IR mediated by serum leptin concentrations was statistically significant (z = 1.588, p < 0.05).

CONCLUSIONS

Taken together, our findings suggest that the relationship between WG during the third trimester and IR was mediated by serum leptin concentrations in AMA, but not serum adiponectin concentrations.

Molecular dynamic (MD) studies on Gln233Arg (rs1137101) polymorphism of leptin receptor gene and associated variations in the anthropometric and metabolic profiles of Saudi women

The Gln233Arg (A>G; rs1137101) polymorphism of the leptin receptor gene (LEPR) has been investigated extensively and is reported to be associated with different metabolic states. In this investigation, we aimed to study the frequency of Gln233Arg genotypes and alleles in a group of Saudi women stratified by their body mass index (BMI), to correlate the LEPR genotypes with variations in anthropometric, lipid and hormonal parameters and to investigate conformational and structural variations in the mutant LEPR using molecular dynamic (MD) investigations. The study group included 122 Saudi women (normal weight = 60; obese = 62) attending the clinics for a routine checkup. Anthropometric data: height, weight, waist and hip circumference were recorded and fasting serum sample was used to estimate glucose, lipids, ghrelin, leptin and insulin. BMI, W/H ratio, and HOMA-IR values were calculated. Whole blood sample was used to extract DNA; exon 6 of the LEPR gene was amplified by PCR and sequencing was conducted on an ABI 3100 Avant Genetic Analyser. Molecular Dynamic Simulation studies were carried out using different softwares. The results showed the presence of all three genotypes of Gln233Arg in Saudi women, but the frequencies were significantly different when compared to reports from some populations. No differences were seen in the genotype and allele frequencies between the normal weight and obese women. Stratification by the genotypes showed significantly higher BMI, waist and hip circumference, leptin, insulin, fasting glucose and HOMA-IR and lower ghrelin levels in obese women carrying the GG genotype. Even in the normal weight group, individuals with GG genotype had higher BMI, waist and hip circumference and significantly lower ghrelin levels. The MD studies showed a significant effect of the Gln/Arg substitution on the conformation, flexibility, root-mean-square fluctuation (RMSF), radius of gyration (Rg) values, solvent-accessible surface area (SASA) and number of inter- and intra-molecular H-bonds. The results suggest that the structural changes brought about by the mutation, influence the signaling pathways by some unknown mechanism, which may be contributing to the abnormalities seen in the individuals carrying the G allele of rs1137101.

Role of insulin, adenosine, and adipokine receptors in the foetoplacental vascular dysfunction in gestational diabetes mellitus

Gestational diabetes mellitus (GDM) is a disease of pregnancy associated with maternal and foetal hyperglycaemia and altered foetoplacental vascular function. Human foetoplacental microvascular and macrovascular endothelium from GDM pregnancy show increased maximal l-arginine transport capacity via the human cationic amino acid transporter 1 (hCAT-1) isoform and nitric oxide (NO) synthesis by the endothelial NO synthase (eNOS). These alterations are paralleled by lower maximal transport activity of the endogenous nucleoside adenosine via the human equilibrative nucleoside transporter 1 (hENT1) and activation of adenosine receptors. A causal relationship has been described for adenosine-activation of A_2A adenosine receptors, hCAT-1, and eNOS activity (i.e. the Adenosine/l-Arginine/Nitric Oxide, ALANO, signalling pathway). Insulin restores these alterations in GDM via activation of insulin receptor A (IR-A) form in the macrovascular but IR-A and IR-B forms in the microcirculation of the human placenta. Adipokines are secreted from adipocytes influencing the foetoplacental metabolic and vascular function. Various adipokines are dysregulated in GDM, with adiponectin and leptin playing major roles. Abnormal plasma concentration of these adipokines and the activation or their receptors are involved in the pathophysiology of GDM. However, involvement of adipokines, adenosine, and insulin receptors and membrane transporters in the aetiology of this disease of pregnancy is unknown. This review focuses on the pathophysiology of insulin and adenosine receptors and l-arginine and adenosine membranes transporters giving an overview of the key adipokines leptin and adiponectin in the foetoplacental vasculature in GDM. This article is part of a Special Issue entitled: Membrane Transporters and Receptors in Pregnancy Metabolic Complications edited by Luis Sobrevia.

Translational science: Newly emerging science in biology and medicine - Lessons from translational research on the natriuretic peptide family and leptin

Translation is the process of turning observations in the laboratory, clinic, and community into interventions that improve the health of individuals and the public, ranging from diagnostics and therapeutics to medical procedures and behavioral changes. Translational research is defined as the effort to traverse a particular step of the translation process for a particular target or disease. Translational science is a newly emerging science, distinct from basic and clinical sciences in biology and medicine, and is a field of investigation focused on understanding the scientific and operational principles underlying each step of the translational process. Advances in translational science will increase the efficacy and safety of translational research in all diagnostic and therapeutic areas. This report examines translational research on novel hormones, the natriuretic peptide family and leptin, which have achieved clinical applications or for which studies are still ongoing, and also emphasizes the lessons that translational science has learned from more than 30 years' experience in translational research.

Associations of cord blood leptin and adiponectin with children's cognitive abilities

Background Adipocytokines may play a role in fetal programming of neurodevelopment. We aimed to investigate the associations between cord blood adipocytokine concentrations and children's intelligence test scores. Methods We used data from two ongoing pregnancy cohorts in North America: the Maternal-Infant Research on Environmental Chemicals (MIREC, n = 429) and Health Outcomes and Measures of the Environment (HOME, n = 183) Studies. Umbilical cord blood adipocytokine concentrations were measured using enzyme-linked immunosorbent assays. We assessed children's Intelligence Quotient (IQ) and its components using the Wechsler Preschool and Primary Scales of Intelligence-III or Wechsler Intelligence Scale for Children-IV. We used linear regression and linear mixed models to estimate associations between log₂-transformed adipocytokine concentrations and children's IQ after adjusting for sociodemographic, perinatal, and child factors. Results After adjusting for covariates, cord blood adiponectin was positively associated with children's full-scale IQ scores at age 3 years in the MIREC Study (β = 1.4, 95% confidence interval [CI]: 0.2, 2.5) and at ages 5 and 8 years in the HOME Study (β = 1.7, CI: -0.1, 3.5). Adiponectin was positively associated with performance IQ in both studies (MIREC: β = 2.0, CI: 0.7, 3.3; HOME: β = 2.2, CI: 0.5, 3.9). Adiponectin was positively associated with working memory composite scores at age 8 in the HOME Study (β = 3.1, CI: 1.0, 5.2). Leptin was not associated with children's IQ in either study. Conclusions Cord blood adiponectin was associated with higher full-scale and performance IQ and working memory composite scores in children. Future studies are needed to explore the mechanisms underlying these associations.

Leptin stimulates DMP-1 and DSPP expression in human dental pulp via MAPK 1/3 and PI3K signaling pathways

INTRODUCTION

To investigate the physiological function of leptin in human dental pulp, and to determine the specific pathways implicated in its effect.

METHODS

Twenty-seven dental pulp samples were obtained from human third molars. Pulp samples were treated with or without human recombinant leptin. Leptin functional effect was analyzed in terms of regulation of the synthesis levels of DSPP and DMP-1, determined by immunoblot.

RESULTS

Leptin stimulated DMP-1 and DSPP synthesis in all human dental pulp specimens. The stimulatory effect of leptin on DMP-1 and DSPP synthesis was partially prevented by blocking mitogen-activated protein kinase (MAPK 1/3) and phosphatidylinositol 3 kinase (PI3K) pathways, respectively.

CONCLUSIONS

The present study demonstrates the functional effect of leptin in human dental pulp stimulating the expression of DMP-1 and DSPP, both proteins implicated in dentinogenesis. Leptin stimulates DSPP expression via PI3K pathway and DMP-1 synthesis via MAPK 1/3 pathway. These results support the role of leptin in pulpal reparative response, opening a new research line that could have translational application to the clinic in vital pulp therapy procedures.

The Pathophysiology of Gestational Diabetes Mellitus

Gestational diabetes mellitus (GDM) is a serious pregnancy complication, in which women without previously diagnosed diabetes develop chronic hyperglycemia during gestation. In most cases, this hyperglycemia is the result of impaired glucose tolerance due to pancreatic β-cell dysfunction on a background of chronic insulin resistance. Risk factors for GDM include overweight and obesity, advanced maternal age, and a family history or any form of diabetes. Consequences of GDM include increased risk of maternal cardiovascular disease and type 2 diabetes and macrosomia and birth complications in the infant. There is also a longer-term risk of obesity, type 2 diabetes, and cardiovascular disease in the child. GDM affects approximately 16.5% of pregnancies worldwide, and this number is set to increase with the escalating obesity epidemic. While several management strategies exist-including insulin and lifestyle interventions-there is not yet a cure or an efficacious prevention strategy. One reason for this is that the molecular mechanisms underlying GDM are poorly defined. This review discusses what is known about the pathophysiology of GDM, and where there are gaps in the literature that warrant further exploration.

Leptin protects placental cells from apoptosis induced by acidic stress

Development of the human placenta is critical for a successful pregnancy. The placenta allows the exchange of oxygen and carbon dioxide and is crucial to manage acid-base balance within a narrow pH. It is known that low pH levels are a risk of apoptosis in several tissues. However, there has been little discussion about the effect of acidic stress in the placenta. Leptin is produced by the placenta with a trophic autocrine effect. Previous results of our group have demonstrated that leptin prevents apoptosis of trophoblast cells under different stress conditions such as serum deprivation and hyperthermia. The purpose of the present work is to evaluate acidic stress consequences in trophoblast explant survival and to determine leptin action in these conditions. For this objective, term human trophoblast explants were cultured at physiological pH (pH 7.4) and at acidic pH (pH 6.8) in the presence or absence of leptin. Western blot assays were performed to study the abundance of active caspase-3 and the p89 fragment of PARP-1. Pro-apoptotic and pro-survival members of Bcl-2 family, as Bax, t-Bid, and Bcl-2, were studied. Moreover, p53 pathway was also evaluated including Mdm-2, the main p53 regulator. Active caspase-3 and cleaved PARP-1 abundances were increased at low extracellular pH. Moreover, t-Bid levels were also augmented as well as p53 expression and phosphorylation on S46. Leptin treatment prevents the consequences of acidosis, decreasing p53 expression and increasing Mdm-2 expression. In summary, this work demonstrated for first time that low pH induces apoptosis of human trophoblast explants involving apoptotic intrinsic pathway, and leptin impairs this effect.

Adipose tissue and reproductive health

The understanding of adipose tissue role has evolved from that of a depot energy storage organ to a dynamic endocrine organ. While genetics, sexual phenotype and sex steroids can impact the mass and distribution of adipose tissue, there is a counter-influence of white adipocytes on reproduction. This primarily occurs via the secretion of adipokines, the most studied of which- leptin and adiponectin- are highlighted in this article. Leptin, the "satiety hormone" primarily acts on the hypothalamus via pro-opiomelanocortin (POMC), neuropeptide Y (NPY), and agouti-related peptide (AgRP) neurons to translate acute changes in nutrition and energy expenditure, as well as chronic adipose accumulation into changes in appetite and potentially mediate insulin resistance via shared pathway and notably impacting reproductive health via influence on GnRH secreting neurons. Meanwhile, adiponectin is notable for its action in mediating insulin sensitivity, with receptors found at every level of the reproductive axis. Both have been examined in the context of physiologic and pathologic reproductive conditions. Leptin has been shown to influence puberty, pregnancy, hypothalamic amenorrhea, and lipodystrophy, and with a potential therapeutic role for both metabolic and reproductive health. Adiponectin mediates the relative state of insulin resistance in pregnancy, and has been implicated in conditions such as polycystic ovary syndrome and reproductive malignancies. There are numerous other adipokines, including resistin, visfatin, chemerin and retinol binding protein-4, which may also play roles in reproductive health and disease states. The continued examination of these and other adipokines in both normal reproduction and reproductive pathologies represents an important avenue for continued study. Here, we seek to provide a broad, yet comprehensive overview of many facets of these relationships and highlight areas of consideration for clinicians and future study.

Mouse Embryonic Fibroblasts Protect ob/ob Mice From Obesity and Metabolic Complications

The global obesity epidemic is fueling alarming rates of diabetes, associated with increased risk of cardiovascular disease and cancer. Leptin is a hormone secreted by adipose tissue that is a key regulator of body weight (BW) and energy expenditure. Leptin-deficient humans and mice are obese, diabetic, and infertile and have hepatic steatosis. Although leptin replacement therapy can alleviate the pathologies seen in leptin-deficient patients and mouse models, treatment is costly and requires daily injections. Because adipocytes are the source of leptin secretion, we investigated whether mouse embryonic fibroblasts (MEFs), capable of forming adipocytes, could be injected into ob/ob mice and prevent the metabolic phenotype seen in these leptin-deficient mice. We performed a single subcutaneous injection of MEFs into leptin-deficient ob/ob mice. The MEF injection formed a single fat pad that is histologically similar to white adipose tissue. The ob/ob mice receiving MEFs (obRs) had significantly lower BW compared with nontreated ob/ob mice, primarily because of decreased adipose tissue mass. Additionally, obR mice had significantly less liver steatosis and greater glucose tolerance and insulin sensitivity. obR mice also manifested lower food intake and greater energy expenditure than ob/ob mice, providing a mechanism underlying their metabolic improvement. Furthermore, obRs have sustained metabolic protection and restoration of fertility. Collectively, our studies show the importance of functional adipocytes in preventing metabolic abnormalities seen in leptin deficiency and point to the possibility of cell-based therapies for the treatment of leptin-deficient states.

The Role of Placental Hormones in Mediating Maternal Adaptations to Support Pregnancy and Lactation

During pregnancy, the mother must adapt her body systems to support nutrient and oxygen supply for growth of the baby in utero and during the subsequent lactation. These include changes in the cardiovascular, pulmonary, immune and metabolic systems of the mother. Failure to appropriately adjust maternal physiology to the pregnant state may result in pregnancy complications, including gestational diabetes and abnormal birth weight, which can further lead to a range of medically significant complications for the mother and baby. The placenta, which forms the functional interface separating the maternal and fetal circulations, is important for mediating adaptations in maternal physiology. It secretes a plethora of hormones into the maternal circulation which modulate her physiology and transfers the oxygen and nutrients available to the fetus for growth. Among these placental hormones, the prolactin-growth hormone family, steroids and neuropeptides play critical roles in driving maternal physiological adaptations during pregnancy. This review examines the changes that occur in maternal physiology in response to pregnancy and the significance of placental hormone production in mediating such changes.

Insulin as a hormone regulator of the synthesis and release of leptin by white adipose tissue

Leptin and its receptor are widely distributed in several tissues, mainly in white adipose tissue. The serum leptin is highly correlated with body mass index in rodents and humans, being documented that leptin levels reduces in the fasting state and increase during refeeding, similarly to insulin release by pancreatic islets. Insulin appears to increase leptin mRNA and protein expression and its release by adipocytes. Some studies have suggested that insulin acts through the activation of the transcription factors: sterol regulatory element binding protein 1 (SREBP1), CCAAT enhancer binding protein-α (C/EBP-α) and specificity protein 1 (Sp1). Insulin stimulates the release of preformed and newly synthesized leptin by adipocytes through its signaling cascade. Its effects are blocked by inhibitors of the insulin signaling pathway, as well as by inhibitors of protein synthesis and agents that increase the intracellular cAMP. The literature data suggest that chronic hyperinsulinemia increases serum leptin levels in humans and rodents. In this review, we summarized the most updated knowledge on the effects of insulin on serum leptin levels, presenting the cell mechanisms that control leptin synthesis and release by the white adipose tissue.

Maternal programming: Application of a developmental psychopathology perspective

The fetal phase of life has long been recognized as a sensitive period of development. Here we posit that pregnancy represents a simultaneous sensitive period for the adult female with broad and persisting consequences for her health and development, including risk for psychopathology. In this review, we examine the transition to motherhood through the lens of developmental psychopathology. Specifically, we summarize the typical and atypical changes in brain and behavior that characterize the perinatal period. We highlight how the exceptional neuroplasticity exhibited by women during this life phase may account for increased vulnerability for psychopathology. Further, we discuss several modes of signaling that are available to the fetus to affect maternal phenotypes (hormones, motor activity, and gene transfer) and also illustrate how evolutionary perspectives can help explain how and why fetal functions may contribute to maternal psychopathology. The developmental psychopathology perspective has spurred advances in understanding risk and resilience for mental health in many domains. As such, it is surprising that this major epoch in the female life span has yet to benefit fully from similar applications.

Correlation of adipokines and markers of oxidative stress in women with gestational diabetes mellitus and their newborns

AIM

We have shown that some markers of oxidative stress were higher in women with gestational diabetes mellitus (GDM). This study examines the relationship between adipokines and oxidative stress and their potential effects in pregnant women.

METHODS

Three markers of oxidative stress (malondialdehyde, 8-isoprostane and xanthine oxidase) and three adipokines (leptin, adiponectin and resistin) were measured in maternal plasma, cord plasma and placenta of 208 pregnant women.

RESULTS

Among all these women, 105 were diagnosed with GDM while the other 103 were controls. Leptin, resistin, malondialdehyde, xanthine oxidase and 8-isoprostane in maternal plasma, cord plasma and placenta were significantly higher while maternal adiponectin significantly lower in women with GDM (P < 0.05). Adipokines in maternal plasma, cord plasma and placenta were positively correlated with markers of oxidative stress. Both markers of oxidative stress and adipokines were correlated inversely with homeostasis model assessment of insulin resistance whereas positively with quantitative insulin sensitivity check index (P < 0.01). Adiponectin is negatively correlated with leptin and resistin. Placental/cord leptin and cord resistin levels were higher in the macrosomia while maternal adiponectin level was lower (P < 0.05) than normal birthweight newborns. Both markers of oxidative stress and adipokines in maternal and cord plasma are negatively correlated with newborn birthweight (P < 0.05).

CONCLUSION

Adipokines interact with markers of oxidative stress, both of which lead to insulin resistance, GDM and macrosomia. It has long been known that placenta involves in the development of GDM. Adipokines might participate in this process and need to be confirmed by further studies.

Leptin action in normal and pathological pregnancies

Leptin is now considered an important signalling molecule of the reproductive system, as it regulates the production of gonadotrophins, the blastocyst formation and implantation, the normal placentation, as well as the foeto-placental communication. Leptin is a peptide hormone secreted mainly by adipose tissue, and the placenta is the second leptin-producing tissue in humans. Placental leptin is an important cytokine which regulates placental functions in an autocrine or paracrine manner. Leptin seems to play a crucial role during the first stages of pregnancy as it modulates critical processes such as proliferation, protein synthesis, invasion and apoptosis in placental cells. Furthermore, deregulation of leptin levels has been correlated with the pathogenesis of various disorders associated with reproduction and gestation, including polycystic ovary syndrome, recurrent miscarriage, gestational diabetes mellitus, pre-eclampsia and intrauterine growth restriction. Due to the relevant incidence of the mentioned diseases and the importance of leptin, we decided to review the latest information available about leptin action in normal and pathological pregnancies to support the idea of leptin as an important factor and/or predictor of diverse disorders associated with reproduction and pregnancy.

Association between Fetal Adipokines and Child Behavioral Problems at Preschool Age: The Hokkaido Study on Environment and Children's Health

Studies have suggested associations between maternal obesity and mental health problems of their children. However, the underlying mechanism is largely unknown. A possible mechanism can be via inflammatory states and the other possible mechanism is metabolic hormone-induced programming. Cross-talk between adipokines, including inflammatory cytokines and metabolic hormones secreted from adipose tissue and the central nervous system needs to be further investigated to elucidate the mechanism. Thus, the aim of this study was to investigate the association between fetal adipokine levels and child behavioral problems at preschool age. Cord blood adiponectin, leptin, tumor necrosis factor-α (TNF-α) and interleukin 6 (IL-6) levels were measured and child behavioral problems were assessed using the Strengths and Difficulties Questionnaire at preschool age. Logistic regression models adjusted by related maternal factors were performed to examine the association between cord blood adipokines and child behavioral problems. Three hundred and sixty-one children were included in the final analysis. A significant association between decreased hyperactivity/inattention and increased leptin was found (OR = 0.22, 95% CI: 0.06–0.89). Cord blood adiponectin, TNF-α and IL-6 levels were not associated with child behavioral problems. Our findings suggested that cord blood adipokines, particularly, leptin level, may be a predictor of hyperactivity/inattention problems at preschool age.

Leptin and soluble leptin receptor in association with gestational diabetes: a prospective case-control study

PURPOSE

To assess the association of serum leptin and its receptor (SLeptinR) with the risk of gestational diabetes mellitus (GDM) and to evaluate the longitudinal circulation of these peptides in pregnancy.

METHODS

This study consisted of 53 subjects diagnosed with GDM and 43 normal glucose tolerance (NGT) pregnant women. Serum leptin and SLeptinR were measured at 24-28 weeks, prior and after delivery, and post-puerperium.

RESULTS

Lower levels of leptin and SLeptinR were observed in GDM compared to NGT. Leptin [OR 0.97 (95% CI 0.94-1.0)] and SLeptinR [OR 0.86 (95% CI 0.79-0.93]) were inversely associated with GDM. Participants in the lowest tertile for leptin and SLeptinR had a 2.8-fold (95% CI 1.0-7.6) and a 5.7-fold (95% CI 1.9-17.3) higher risk of developing GDM compared with the highest tertile, respectively. These relationships were attenuated after adjustment for covariates. In both the groups, peak leptin was observed at 24-28 weeks, decreasing continuously during pregnancy (p > 0.05) and after delivery (p < 0.017). SLeptinR level increased (p < 0.001) during pregnancy and decreased (p < 0.005) after delivery in GDM, however, levels remained the same in NGT. In GDM, leptin and SLeptinR was positively and inversely correlated with BMI and HOMA-IR at 24-28 weeks and post-puerperium, respectively. The cord levels of both leptin and SLeptinR were lower than maternal levels. There were no significant differences in serum cord leptin and SLeptinR levels between the groups.

CONCLUSION

Leptin and SLeptinR are independently and inversely associated with GDM. Lower levels of these peptides may play an important role in the pathophysiology of GDM and pre-diabetic state in post-puerperium.

Effects of maternal and fetal LEP common variants on maternal glycemic traits in pregnancy

Previous studies suggest that leptin (LEP) has an important role in glucose metabolism in the nonpregnant state. During pregnancy, circulating maternal concentrations of leptin rise significantly, mainly due to increased secretion of leptin from maternal adipose tissue and placenta. This study aimed to analyze the impact of maternal and fetal common LEP variants on glucose homeostasis in the pregnant state. Several glycemic traits, including fasting plasma glucose, fasting plasma insulin (FPI), and plasma glucose 1 hour after a 50-g oral glucose load, were measured in 1,112 unrelated Chinese Han pregnant women at 24–28 weeks gestation. Homeostatic model assessment (HOMA) was used to assess beta cell function (HOMA1-β and HOMA2-β) and insulin resistance (HOMA1-IR and HOMA2-IR).The relationships between glycemic traits and 12 LEP variants were determined. After applying the Bonferroni correction, we detected that (1) maternal rs10954173 and fetal rs10244329 were associated with maternal FPI although the effect of fetal rs10244329 may be not independent of maternal rs10244329, and (2) maternal rs12537573 was associated with maternal FPI and HOMA2-IR. This study provides genetic evidence that both maternal and fetal LEP polymorphisms may affect maternal glucose metabolism in pregnancy.

Long-lived weight-reduced αMUPA mice show higher and longer maternal-dependent postnatal leptin surge

We investigated whether long-lived weight-reduced αMUPA mice differ from their wild types in postnatal body composition and leptin level, and whether these differences are affected by maternal-borne factors. Newborn αMUPA and wild type mice had similar body weight and composition up to the third postnatal week, after which αMUPA mice maintained lower body weight due to lower fat-free mass. Both strains showed a surge in leptin levels at the second postnatal week, initiating earlier in αMUPA mice, rising higher and lasting longer than in the wild types, mainly in females. Leptin level in dams' serum and breast milk, and in their pup's stomach content were also higher in αMUPA than in the WT during the surge peak. Leptin surge preceded the strain divergence in body weight, and was associated with an age-dependent decrease in the leptin:fat mass ratio-suggesting that postnatal sex and strain differences in leptin ontogeny are strongly influenced by processes independent of fat mass, such as production and secretion, and possibly outside fat tissues. Dam removal elevated corticosterone level in female pups from both strains similarly, yet mitigated the leptin surge only in αMUPA-eliminating the strain differences in leptin levels. Overall, our results indicate that αMUPA's postnatal leptin surge is more pronounced than in the wild type, more sensitive to maternal deprivation, less related to pup's total adiposity, and is associated with a lower post-weaning fat-free mass. These strain-related postnatal differences may be related to αMUPA's higher milk-borne leptin levels. Thus, our results support the use of αMUPA mice in future studies aimed to explore the relationship between maternal (i.e. milk-borne) factors, postnatal leptin levels, and post-weaning body composition and energy homeostasis.

Postpartum maternal adipokines and infant weight for length at 1 year in women with gestational diabetes

BACKGROUND

Maternal, cord blood and childhood adipokines have been associated with childhood obesity. We investigated whether postpartum maternal adipokines are associated with increased weight at 1 year of age in children of women with gestational diabetes (GDM).

METHODS

Plasma leptin and adiponectin concentrations were measured in 160 women at approximately 12 weeks following pregnancy with GDM and compared with infant weight for length z-score at 1 year of age after adjustment for maternal and infant demographic variables.

RESULTS

No association was demonstrated between maternal postpartum leptin and adiponectin concentrations and infant weight for length z-score at 1 year of age.

Involvement of leptin in the molecular physiology of the placenta

Leptin is a homeostatic regulator in the placenta where it promotes proliferation, protein synthesis and the expression of tolerogenic maternal response molecules such as HLA-G. Leptin also exerts an anti-apoptotic action in placenta controlling the expression of p53 master cell cycle regulator under different stress conditions. On the other hand, leptin is an integrative target of different placental stimuli. The expression of leptin in placenta is regulated by hCG, insulin, steroids, hypoxia and many other growth hormones, suggesting that it might have an important endocrine function in the trophoblastic cells. The leptin expression is induced involving the cAMP/PKA or cAMP/Epac pathways which have profound actions upon human trophoblast function. The activation of PI3K and MAPK pathways also participates in the leptin expression. Estrogens play a central role during pregnancy, particularly 17β-estradiol upregulates the leptin expression in placental cells through genomic and non-genomic actions. The leptin promoter analysis reveals specific elements that are active in placental cells. The transcription factors CREB, AP1, Sp1, NFκB and the coactivator CBP are involved in the placental leptin expression. Moreover, placental leptin promoter is a target of epigenetic marks such as DNA methylation and histone acetylation that regulates not only the leptin expression in placenta during pregnancy but also determines the predisposition of acquiring adult metabolism diseases. Taken together, all these results allow a better understanding of leptin function and regulatory mechanisms of leptin expression in human placental trophoblasts, and support the importance of leptin during pregnancy and in programming adult health.

Adiposity and hyperleptinemia during the first trimester among pregnant women with preeclampsia

BACKGROUND

Leptin levels start increasing from the early stages of pregnancy, irrespective of the maternal body mass index. Leptin levels are increased in pregnant women with preeclampsia (PE) and may precede the clinical onset of the disease, with peaks occurring around 28 weeks of gestation. This study was aimed at determining whether serum leptin concentration and body fat percentage are significantly altered during the first trimester in pregnancies that subsequently develop PE and whether such changes are useful in predicting the disease.

MATERIALS AND METHODS

This was a prospective longitudinal study conducted among pregnant women in Ho municipality. A cohort of 314 pregnant women was monitored from the first antenatal visit to delivery period at the Volta Regional Hospital, Ho, Ghana. Maternal serum leptin and lipid profile were analyzed and body fat percentage determined during first trimester. Body mass index was also calculated.

RESULTS

First trimester serum leptin level (P<0.0001) and body fat percentage (P<0.0001) were significantly higher in those who developed PE than those who did not; while triglycerides (P=0.8600), total cholesterol (P=0.5620), high-density lipoprotein (P=0.5880), low-density lipoprotein (P=0.4870) and very low-density lipoprotein (P=0.6540) did not show any significant difference between those with PE and those without PE.

CONCLUSION

Leptin levels are increased significantly during the first trimester of pregnancy in obese women with PE, and these increases precede the onset of PE.

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

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

Expression of leptin receptor in the oviduct of Chinese brown frog (Rana dybowskii)

The oviduct of Chinese brown frog ( Rana dybowskii) expands specifically during prehibernation instead of in the breeding period. In this study, we investigated the expression of leptin receptor (Ob-Rb) in Rana dybowskii oviduct during the breeding period and prehibernation. Histologically, the oviduct of Rana dybowskii consists of glandular cells, tubule lumen, and epithelial cells. The oviductal weight and pipe diameter also revealed significant differences, which were higher in prehibernation than that of the breeding period. Ob-Rb was observed in stromal cells of oviductal tissue in both the breeding period and prehibernation. The mean protein and mRNA levels of the Ob-Rb were significantly higher in prehibernation as compared with the breeding period. In addition, oviductal content of leptin was also higher in prehibernation than that of the breeding period. These results suggested that oviduct of Rana dybowskii might be a target organ of leptin, and leptin may play an autocrine/paracrine role mediated by Ob-Rb in regulating the oviductal hypertrophy during prehibernation.

The glucoregulatory actions of leptin

Background

The hormone leptin is an important regulator of metabolic homeostasis, able to inhibit food intake and increase energy expenditure. Leptin can also independently lower blood glucose levels, particularly in hyperglycemic models of leptin or insulin deficiency. Despite significant efforts and relevance to diabetes, the mechanisms by which leptin acts to regulate blood glucose levels are not fully understood.

Scope of review

Here we assess literature relevant to the glucose lowering effects of leptin. Leptin receptors are widely expressed in multiple cell types, and we describe both peripheral and central effects of leptin that may be involved in lowering blood glucose. In addition, we summarize the potential clinical application of leptin in regulating glucose homeostasis.

Major conclusions

Leptin exerts a plethora of metabolic effects on various tissues including suppressing production of glucagon and corticosterone, increasing glucose uptake, and inhibiting hepatic glucose output. A more in-depth understanding of the mechanisms of the glucose-lowering actions of leptin may reveal new strategies to treat metabolic disorders.

Salivary leptin levels in normal weight and overweight individuals and their correlation with orthodontic tooth movement

OBJECTIVES

To assess and compare the concentration of leptin in saliva between normal weight and overweight individuals and to evaluate the rate of orthodontic tooth movement.

MATERIALS AND METHODS

Thirty female subjects were divided into two groups: I (normal weight) and II (overweight group) based on their body mass index. All subjects underwent fixed appliance therapy requiring upper first premolar extraction and distal movement of the canine. Distal force was applied to the maxillary right canine using active lacebacks. Salivary samples were collected just before force application (T₀), 1 hour (T₁), and 1 month (T₂) after force application. The rate of tooth movement was evaluated over 3 months and was measured on study models.

RESULTS

At all three time intervals, mean leptin concentration was greater in overweight individuals than normal weight individuals. In both groups at T₁, the mean leptin concentration was found to increase significantly compared with the baseline value (T₀), but at T₂, the leptin concentration declined to values lesser than the baseline values (T₀).

CONCLUSIONS

Overweight individuals had greater salivary leptin concentration. There was a positive correlation between salivary leptin concentration and rate of tooth movement in both normal and overweight individuals. The rate of tooth movement is decreased in overweight individuals as compared with normal weight individuals.

Markers of obesity and growth in preeclamptic and normotensive pregnant women

The objective of the study was to analyse leptin, IGF-1, Apo A, lipoproteins, haem oxygenase-1 (HO-1) in maternal sera and venous umbilical cord sera of newborn babies of 25 preeclamptics (group II), and 25 normotensive pregnant women (group I) as markers of obesity and growth in preeclamptic and normotensive pregnant women. Apo A I and II levels were estimated by competitive immunoassay using direct chemiluminiscence technology. Haem oxygenase-1 (HO-1), leptin and IGF-1 were analysed by ELISA. Maternal and cord blood levels of homocysteine, folic acid, lipid profile (namely, total cholesterol, triglycerides, LDL-C, VLDL-C and HDL-C), Haem oxygenase 1 were higher in preeclamptic women as compared to normotensive pregnant women. Serum and cord blood Apo A-I and Apo B, leptin levels, IGF-I were lower in preeclamptic women as compared to normotensive pregnant. The findings of high serum HO-1 levels in maternal and cord blood in preeclampsia supports the role of oxidative stress and excessive inflammatory response in the pathogenesis of preeclampsia. It seems likely that IGF-1 and leptin play a central role in controlling foetal growth. There is increasing evidence that the foundations of life-long health are, in part, laid in the uterus. Findings of present study suggest that alterations in biochemical markers of growth and obesity occur in mothers and foetuses and modifications of uterine environment can be of help to prevent future cardiovascular risk. Impact statement Preeclampsia has been reported to be associated with an increased risk of later life cardiovascular disease. However, information regarding how obesity increases the risk of preeclampsia is limited. Atherogenic milieu occurring during pregnancy persists into adulthood and foetal growth retardation is strongly associated with adult atherosclerosis. There is conflicting evidence regarding alterations of IGFs in preeclamptic pregnancies and deficit in circulating and cord blood IGF-1 levels in intrauterine growth restricted newborns and a correlation between IGF-1 levels and birth weight have been reported. Leptin is a predictor of cardiovascular risk independent of insulin resistance. Emerging evidence supports an important role for the haem oxygenase system (HO-1) in the maintenance of a healthy pregnancy, especially during pathological challenge. Conflicting data are available regarding HO-1, leptin and IGF -1 in preeclamptic mothers. The extent to which they mediate foetal growth and developmental abnormalities remains to be clarified. Serum IGF-1 levels were significantly decreased in preeclamptics and maternal IGF-1 showed a strong inverse correlation with leptin levels. High serum HO-1 levels in maternal and cord blood in preeclampsia were observed in the present study. Findings of the present study suggest that alterations in biochemical markers of growth and obesity occur in mothers and foetuses and modifications of the uterine environment can be of help to prevent future cardiovascular risk.

Genetic determinants of adiponectin regulation revealed by pregnancy

OBJECTIVE

This study investigated genetic determinants of adiponectin during pregnancy to reveal novel biology of adipocyte regulation.

METHODS

A genome-wide association study was conducted in 1,322 pregnant women from the Hyperglycemia and Adverse Pregnancy Outcome Study with adiponectin measured at ∼28 weeks of gestation. Variants reaching P < 5×10^-5 for de novo genotyping in two replication cohorts (Genetics of Glycemic regulation in Gestation and Growth N = 522; ECOGENE-21 N = 174) were selected.

RESULTS

In the combined meta-analysis, the maternal T allele of rs900400 located on chr3q25 (near LEKR1/CCNL1) was associated with lower maternal adiponectin (β ± standard error [SE] = -0.18 ± 0.03 standard deviation [SD] of adiponectin per risk allele; P = 1.5 ×10^-8 ; N = 2,004; multivariable adjusted models). In contrast, rs900400 showed only nominal association with adiponectin in a large sample of nonpregnant women (β ± SE = -0.012 ± 0.006; P = 0.05; N = 16,678 women from the ADIPOgen consortium). The offspring rs900400 T risk allele was associated with greater neonatal skinfold thickness (β ±SE = 0.19 ± 0.04 SD per risk allele; P = 4.1×10^-8 ; N = 1,489) and higher cord blood leptin (β ± SE = 0.28 ± 0.05 log-leptin per risk allele; P = 8.2 ×10^-9 ; N = 502), but not with cord blood adiponectin (P = 0.23; N = 495). The T allele of rs900400 was associated with higher expression of TIPARP in adipocytes.

CONCLUSIONS

These investigations of adipokines during pregnancy and early life suggest that rs900400 has a role in adipocyte function.

Maternal metabolic adaptations to pregnancy among young women in Cebu, Philippines

OBJECTIVES

Evidence that fetal development has long-term impacts on health has increased interest in maternal-fetal nutrient exchange. Although maternal metabolism is known to change during gestation to accommodate fetal nutrient demands, little is known about these modifications outside of a Western, clinical context. This study characterizes maternal metabolic adaptations to pregnancy, and their associations with offspring birth weight (BW), among women living in the Philippines.

METHODS

Fasting glucose, triglycerides, insulin, leptin, and adiponectin were assessed in 808 participants in the Cebu Longitudinal Health and Nutrition Survey (Metropolitan Cebu, Philippines). Cross-sectional relationships between metabolites and hormones and gestational and lactational status were evaluated. Among the subset of currently pregnant women, associations between maternal glucose and triglycerides and offspring BW were also examined.

RESULTS

Women in their second and third trimesters had significantly lower fasting glucose and adiponectin compared to nulliparous women, and leptin levels and triglyceride levels were notably higher late in pregnancy (all P < .05). Among pregnant women, fasting glucose was a positive predictor of offspring BW, but only in males (P = .012, R²  = .28). Hormones and metabolites in post-partum women trend back toward levels found in nulliparous women, with some differences by breastfeeding status.

CONCLUSIONS

We find evidence for marked changes in maternal lipid and carbohydrate metabolism during pregnancy, consistent with known adaptations to support fetal growth. The finding of sex-specific relationships between maternal glucose and offspring BW adds to evidence for greater impacts of the maternal-gestational environment on biology and health in male offspring.

Uterine artery leptin receptors during the ovarian cycle and pregnancy regulate angiogenesis in ovine uterine artery endothelial cells†

Leptin regulates body weight, reproductive functions, blood pressure, endothelial function, and fetoplacental angiogenesis. Compared to the luteal phase, the follicular phase and pregnancy are physiological states of elevated estrogen, angiogenesis, and uterine blood flow (UBF). Little is known concerning regulation of uterine artery (UA) angiogenesis by leptin and its receptors. We hypothesized that (1) ex vivo expression of leptin receptors (LEPR) in UA endothelium (UAendo) and UA vascular smooth muscle (UAvsm) is elevated in pregnant versus nonpregnant (Luteal and Follicular) sheep; (2) in vitro leptin treatments differentially modulate mitogenesis in uterine artery endothelial cells from pregnant (P-UAECs) more than in nonpregnant (NP-UAECs) ewes; and (3) LEPR are upregulated in P-UAECs versus NP-UAECs in association with leptin activation of phospho-STAT3 signaling. Local UA adaptations were evaluated using a unilateral pregnant sheep model where prebreeding uterine horn isolation (nongravid) restricted gravidity to one horn. Immunolocalization revealed LEPR in UAendo and UAvsm from pregnant and nonpregnant sheep. Contrary to our hypothesis, western analysis revealed that follicular UAendo and UAvsm LEPR were greater than luteal, nongravid, gravid, and control pregnant. Compared to pregnant groups, LEPR were elevated in renal artery endothelium of follicular and luteal sheep. Leptin treatment significantly increased mitogenesis in follicular phase NP-UAECs and P-UAECs, but not luteal phase NP-UAECs. Although UAEC expression of LEPR was similar between groups, leptin treatment only activated phospho-STAT3 in follicular NP-UAECs and P-UAECs. Thus, leptin may play an angiogenic role particularly in preparation for the increased UBF during the periovulatory period and subsequently to meet the demands of the growing fetus.

Association of prenatal antibiotics with foetal size and cord blood leptin and adiponectin

BACKGROUND

Early postnatal antibiotic use has been shown to promote excess weight gain, but it is unclear whether intrauterine exposure to antibiotics is associated with foetal growth and adiposity. The objective of this study was to examine associations of antibiotic prescription in each trimester of pregnancy with foetal size and adipokine levels at birth.

METHODS

In 2128 pregnant women from the pre-birth Project Viva cohort, from electronic medical records, we estimated antibiotic prescribing by timing during pregnancy. Outcomes were sex-specific birth weight-for-gestational-age z-score (BW/GA-z) and levels of umbilical cord leptin and adiponectin. We used linear regression models adjusted for maternal age, pre-pregnancy body mass index, parity, race/ethnicity, education, smoking during pregnancy, household income and child sex and additionally adjusted cord blood leptin and adiponectin models for gestation length.

RESULTS

Of the 2128 women in our sample, 643 (30.2%) were prescribed with oral antibiotics during pregnancy. Mean (standard deviation) BW/GA-z was 0.17 (0.97), cord blood leptin was 9.0 ng mL-1 (6.6) and cord blood adiponectin was 28.8 ng mL-1 (6.8). Overall, antibiotic prescription in pregnancy was associated with lower BW/GA-z [multivariable adjusted β -0.11; 95% confidence interval {CI} -0.20, -0.01]. In trimester-specific analyses, only second trimester antibiotic prescription was associated with lower BW/GA-z (β -0.23; 95% CI -0.37, -0.08). Overall, antibiotic prescription in pregnancy was not associated with cord blood leptin or adiponectin levels. However, in trimester-specific analyses, third trimester antibiotic prescription was associated with higher cord blood leptin (β 2.28 ng mL-1 ; 95% CI 0.38, 4.17).

CONCLUSIONS

Antibiotics in mid-pregnancy were associated with lower birth weight for gestational age, whereas third trimester antibiotics were associated with higher cord blood leptin.

Circadian Rhythms in Adipose Tissue Physiology

The different types of adipose tissues fulfill a wide range of biological functions-from energy storage to hormone secretion and thermogenesis-many of which show pronounced variations over the course of the day. Such 24-h rhythms in physiology and behavior are coordinated by endogenous circadian clocks found in all tissues and cells, including adipocytes. At the molecular level, these clocks are based on interlocked transcriptional-translational feedback loops comprised of a set of clock genes/proteins. Tissue-specific clock-controlled transcriptional programs translate time-of-day information into physiologically relevant signals. In adipose tissues, clock gene control has been documented for adipocyte proliferation and differentiation, lipid metabolism as well as endocrine function and other adipose oscillations are under control of systemic signals tied to endocrine, neuronal, or behavioral rhythms. Circadian rhythm disruption, for example, by night shift work or through genetic alterations, is associated with changes in adipocyte metabolism and hormone secretion. At the same time, adipose metabolic state feeds back to central and peripheral clocks, adjusting behavioral and physiological rhythms. In this overview article, we summarize our current knowledge about the crosstalk between circadian clocks and energy metabolism with a focus on adipose physiology. © 2017 American Physiological Society. Compr Physiol 7:383-427, 2017.

The Relationship between Maternal Plasma Leptin and Adiponectin Concentrations and Newborn Adiposity

Increased maternal blood concentrations of leptin and decreased adiponectin levels, which are common disturbances in obesity, may be involved in offspring adiposity by programming fetal adipose tissue development. The aim of this study was to assess the relationship between maternal leptin and adiponectin concentrations and newborn adiposity. This was a cross-sectional study involving 210 healthy mother-newborn pairs from a public maternity hospital in São Paulo, Brazil. Maternal blood samples were collected after delivery and leptin and adiponectin concentrations were measured by enzyme-linked immunosorbent assay. Newborn body composition was estimated by air displacement plethysmography. The association between maternal leptin and adiponectin concentrations and newborn adiposity (fat mass percentage, FM%) was evaluated by multiple linear regression, controlling for maternal age, socioeconomic status, parity, pre-pregnancy body mass index (BMI), weight gain, gestational age, and newborn age at the time of measurement. No relationship was found between maternal leptin and FM% of male or female newborn infants. Maternal adiponectin (p = 0.001) and pre-pregnancy BMI (p < 0.001; adj. R² = 0.19) were positively associated with FM% of newborn males, indicating that maternal adiponectin is involved in fetal fat deposition in a sex-specific manner. Large-scale epidemiological, longitudinal studies are necessary to confirm our results.

Association between Serum Thyroid-Stimulating Hormone Levels and Visceral Adipose Tissue: A Population-Based Study in Northeast Germany

BACKGROUND

Abdominal obesity is a major driver for adverse medical conditions. While an interaction between adipose tissue and thyroid function is thought to exist, to our knowledge, no study has examined the effect of thyroid-stimulating hormone (TSH) on visceral adipose tissue (VAT) in a population-based context.

OBJECTIVE

We determined an association between serum TSH levels and VAT.

METHODS

A sample of 1,021 female and 956 male adults aged 20-79 years was drawn from registry offices in the cross-sectional, population-based Study of Health in Pomerania Trend (SHIP Trend) in Northeast Germany from 2008 to 2012. Our main exposure was serum TSH levels. Our main outcome was VAT measured using magnetic resonance imaging. The possibly mediating role of leptin on the TSH-VAT association was also assessed.

RESULTS

A total of 1,719 participants (87.9%) had serum TSH levels within the reference range. The mean volume of VAT was 5.33 liters for men and 2.83 liters for women. No association between TSH and VAT (β = 0.06, 95% CI: -0.02, 0.14) was observed, and there were no differences detected between sexes. VAT was strongly associated with leptin with a greater effect in women than in men. Leptin was strongly associated with TSH.

CONCLUSIONS

No association between TSH and VAT was observed. Other biomarkers such as leptin may play a role in the relationship between thyroid function and metabolic risk.

Early Pregnancy Biochemical Predictors of Gestational Diabetes Mellitus

PURPOSE OF REVIEW

Universal oral glucose tolerance-based screening is employed to identify pregnant women with gestational diabetes mellitus (GDM), as treatment of this condition decreases the risk of associated complications. A simple and accurate blood test which identifies women at low or high risk for GDM in the first trimester would have the potential to decrease costs and improve outcomes through prevention or treatment. This review summarizes published data on early pregnancy biomarkers which have been tested as predictors of GDM.

RECENT FINDINGS

A large number of first-trimester biochemical predictors of GDM have been reported, mostly in small case-control studies. These include glycemic markers (fasting glucose, post-load glucose, hemoglobin A1C), inflammatory markers (C-reactive protein, tumor necrosis factor-alpha), insulin resistance markers (fasting insulin, sex hormone-binding globulin), adipocyte-derived markers (adiponectin, leptin), placenta-derived markers (follistatin-like-3, placental growth factor, placental exosomes), and others (e.g., glycosylated fibronectin, soluble (pro)renin receptor, alanine aminotransferase, ferritin). A few large studies suggest that first-trimester fasting glucose or hemoglobin A1C may be useful for identifying women who would benefit from early GDM treatment. To translate the findings from observational studies of first-trimester biomarkers for GDM to clinical practice, trials or cost-effectiveness analyses of screening and treatment strategies based on these novel biomarkers are needed.

Review: Placental derived biomarkers of pregnancy disorders

Pregnancy is one of the greatest physiological challenges that a women can experience. The physiological adaptations that accompany pregnancy may increase the risk of developing a number of disorders that can lead to both acute and chronic physiological outcomes. In addition, fetal development may be impaired and, if the fetus survives, the child may be at an increased risk of disease throughout life. Pregnancy disorders are poorly predicted by traditional risk factors and maternal history alone. The identification of biomarkers that can predict incidence and severity of disease would allow for improved and targeted prophylactic therapies to prevent adverse maternal and fetal outcomes. Many of these pregnancy disorders, including preeclampsia, intrauterine growth restriction, gestational diabetes mellitus and preterm birth are known to be regulated at least in part by poor trophoblast invasion and/or dysregulated placental function. Cellular stress within the placenta increases the release of a number of factors into the maternal circulation. While many of these factors minimally impact maternal biology, others affect key physiological systems and contribute to disease. Importantly, these factors may be detected in physiological fluids and have predictive capacity making them ideal candidates as biomarkers of pregnancy disorders. This review will discuss what is known about these placental derived biomarkers of pregnancy disorders and highlight potential clinical opportunities for disease prediction and diagnosis.

Secretory function of adipose tissue

There are two kinds of adipose tissue in mammals: white adipose tissue - WAT and brown adipose tissue - BAT. The main function of WAT is accumulation of triacylglycerols whereas the function of BAT is heat generation. At present, WAT is also considered to be an endocrine gland that produces bioactive adipokines, which take part in glucose and lipid metabolism. Considering its endocrine function, the adipose tissue is not a homogeneous gland but a group of a few glands which act differently. Studies on the secretory function of WAT began in 1994 after discovery of leptin known as the satiation hormone, which regulates body energy homeostasis and maintainence of body mass. Apart from leptin, the following belong to adipokines: adiponectin, resistin, apelin, visfatin and cytokines: TNF and IL 6. Adiponectin is a polypeptide hormone of antidiabetic, anti-inflammatory and anti-atherogenic activity. It plays a key role in carbohydrate and fat metabolism. Resistin exerts a counter effect compared to adiponectin and its physiological role is to maintain fasting glycaemia. Visfatin stimulates insulin secretion and increases insulin sensitivity and glucose uptake by muscle cells and adipocytes. Apelin probably increases the insulin sensitivity of tissues. TNF evokes insulin resistance by blocking insulin receptors and inhibits insulin secretion. Approximately 30% of circulating IL 6 comes from adipose tissue. It causes insulin resistance by decreasing the expression of insulin receptors, decreases adipogenesis and adiponectin and visfatin secretion, and stimulates hepatic gluconeogenesis. In 2004, Bays introduced the notion of adiposopathy, defined as dysfunction of the adipose tissue, whose main feature is insulin and leptin resistance as well as the production of inflammatory cytokines: TNF and IL 6 and monocyte chemoattractant protein. This means that excess of adipose tissue, especially visceral adipose tissue, leads to the development of a chronic subclinical inflammatory condition, which favours the development of insulin resistance and Type 2 diabetes. Obesity is a systemic illness caused by energy transformation homeostasis disorder which results in an increase in the amount of body fat mass. It effects approximately 40% of dogs and 20% of cats. Illnesses which accompany obesity result, to a great extent, from the secretive role of adipose tissue, which is still little known, which should be included when planning treatment of an obese animal.

Cross Talk between Adipose Tissue and Placenta in Obese and Gestational Diabetes Mellitus Pregnancies via Exosomes

Obesity is an important public health issue worldwide, where it is commonly associated with the development of metabolic disorders, especially insulin resistance (IR). Maternal obesity is associated with an increased risk of pregnancy complications, especially gestational diabetes mellitus (GDM). Metabolism is a vital process for energy production and the maintenance of essential cellular functions. Excess energy storage is predominantly regulated by the adipose tissue. Primarily made up of adipocytes, adipose tissue acts as the body's major energy reservoir. The role of adipose tissue, however, is not restricted to a "bag of fat." The adipose tissue is an endocrine organ, secreting various adipokines, enzymes, growth factors, and hormones that take part in glucose and lipid metabolism. In obesity, the greater portion of the adipose tissue comprises fat, and there is increased pro-inflammatory cytokine secretion, macrophage infiltration, and reduced insulin sensitivity. Obesity contributes to systemic IR and its associated metabolic complications. Similar to adipose tissue, the placenta is also an endocrine organ. During pregnancy, the placenta secretes various molecules to maintain pregnancy physiology. In addition, the placenta plays an important role in metabolism and exchange of nutrients between mother and fetus. Inflammation at the placenta may contribute to the severity of maternal IR and her likelihood of developing GDM and may also mediate the adverse consequences of obesity and GDM on the fetus. Interestingly, studies on maternal insulin sensitivity and secretion of placental hormones have not shown a positive correlation between these phenomena. Recently, a great interest in the field of extracellular vesicles (EVs) has been observed in the literature. EVs are produced by a wide range of cells and are present in all biological fluids. EVs are involved in cell-to-cell communication. Recent evidence points to an association between adipose tissue-derived EVs and metabolic syndrome in obesity. In this review, we will discuss the changes in human placenta and adipose tissue in GDM and obesity and summarize the findings regarding the role of adipose tissue and placenta-derived EVs, with an emphasis on exosomes in obesity, and the contribution of obesity to the development of GDM.

Leptin pharmacokinetics in male mice

Pharmacokinetics of leptin in mammals has not been studied in detail and only one study has examined more than one time point in non-mutant mice and this was in a female mice. This is the first study to describe leptin distribution over a detailed time course in normal male mice. A physiologic dose (12 ng) of radiolabelled leptin was injected into adult male mice via the lateral tail vein and tissues were dissected out and measured for radioactivity over a time course of up to two hours. Major targets were the digestive tract, kidneys, skin and lungs. The brain was not a major target, and 0.15% of the total dose was recovered from the brain 5 min after administration. Major differences appear to exist in the distribution of leptin between the male and female mice, indicating a high degree of sexual dimorphism. Although the half-lives were similar between male and female mice, almost twice the proportion of leptin was recovered from the digestive tract of male mice in comparison to that reported previously for females. This would seem to indicate a major difference in leptin distribution and possibly function between males and females.