The role of the leptin in reproduction

Association of adipocytokines and adipocytokine ratios with cardiovascular risk factors in Japanese preadolescents

OBJECTIVES

Asians are particularly susceptible to obesity-associated disorders and rapid progression of obesity from childhood to adulthood. Data on the association between adipocytokine parameters, particularly adipocytokine ratios, and cardiovascular risk factors in childhood remain limited. Herein, we assessed the association of resistin, adiponectin, and leptin levels and leptin/adiponectin and resistin/adiponectin ratios with selected cardiovascular risk factors and the influence of unhealthy weight on such associations in children aged 9-10 years.

METHODS

We included 380 children aged 9-10 years from three public elementary schools in Japan.

RESULTS

The body mass index (BMI) was significantly higher in male preadolescents than in female adolescents (median 16.5 kg/m² vs. 16.2 kg/m², p=0.032). No differences in height, weight, waist circumference (WC), waist/height ratio (W/Hr), total cholesterol and high-density lipoprotein cholesterol levels, or atherosclerosis index (AI) were observed between the sexes. Of the adipocytokine levels and ratios analyzed, only the leptin level and leptin/adiponectin ratio (L/Ar) were strongly and significantly positively correlated with the cardiovascular risk factors WC, W/Hr, and BMI (all p<0.05). The AI was not strongly correlated with any adipocytokine levels or ratios. Apart from the strong positive correlation between the L/Ar and W/Hr, no other significant associations were observed between any of the adipocytokine levels or ratios and the selected cardiovascular risk factors.

CONCLUSIONS

Our findings confirmed the value of adipocytokine ratios in risk assessment in pediatric populations, with leptin levels and leptin/adiponectin ratios strongly correlating with risk factors in children aged 9-10 years.

FGF21 decreases food intake and body weight in obese Göttingen minipigs

AIMS

The aim of this study was to assess the effect of FGF21 on food intake, body weight, body composition, glucose homeostasis, bone mineral density (BMD), cortisol and growth hormone (GH) in obese minipigs. The pig is a unique model for studying FGF21 pharmacology as it does not express UCP1, unlike mice and humans.

METHODS

Twelve obese Göttingen minipigs with a mean body weight of 91.6 ± 6.7 kg (mean ± SD) received subcutaneously either vehicle (n = 6) or recombinant human FGF21 (n = 6) once daily for 14 weeks (0.1 mg/kg for 9.5 weeks and 0.3 mg/kg for 4.5 weeks).

RESULTS

Treatment of obese minipigs with FGF21 led to a 50% reduction in food intake and a body weight loss of, on average, 18 kg compared to the vehicle group after 14 weeks of dosing. Glucose tolerance and insulin sensitivity, evaluated by intravenous glucose tolerance test, were significantly improved in the FGF21 group compared to the vehicle group at the end of the study. The plasma cortisol profile was unaffected by FGF21, whereas a small decrease in peak GH values was observed in the FGF21-treated animals after 7 to 9.5 weeks of treatment compared to the vehicle group. Whole-body BMD was not affected by 13 weeks of FGF21 dosing.

CONCLUSION

Despite a lack of UCP-1 in obese minipigs, FGF21 treatment induced a significant weight loss, primarily a result of reduction in food intake, with no adverse effect on BMD or plasma cortisol.

Leptin in depression: a potential therapeutic target

Leptin, produced and secreted by white adipose tissue, plays a critical role in regulating body weight, food intake, and energy metabolism. Recently, several studies have identified an underlying role for leptin in regulation of mood and cognition via regulation of synaptic changes in the brain that have been associated with antidepressant-like actions. Brain neural plasticity occurs in response to a range of intrinsic and extrinsic stimuli, including those that may mediate the effects of antidepressants. Neural plasticity theories of depression are thought to explain multiple aspects of depression and the effects of antidepressants. It is also well documented that leptin has effects on neural plasticity. This review summarizes the recent literature on the role of leptin in neural plasticity in order to elaborate the possible mechanism of leptin’s antidepressant-like effects. Recent findings provide new insights into the underlying mechanisms of neural plasticity in depression. Leptin may influence these mechanisms and consequently constitute a possible target for novel therapeutic approaches to the treatment of depression.

Polymorphisms in the leptin (rs7799039) gene are associated with an increased risk of excessive gestational weight gain but not with leptin concentration during pregnancy

Single nucleotide polymorphisms (SNPs) in leptin (LEP) and leptin receptor (LEPR) have been shown to be linked to obesity-related metabolic markers and phenotype. Therefore, we hypothesized that the LEP-rs7799039 and LEPR-rs1137101 SNPs are related to the risk of pre-pregnancy overweight/obesity (body mass index ≥25 kg/m²) as well as to excessive gestational weight gain (GWG) and high concentrations of leptin throughout pregnancy. We investigated a prospective cohort of 147 Brazilian pregnant women through weeks 5-13, 20-26, and 30-36 of gestation. Genetic variants of LEP and LEPR were analyzed by real-time polymerase chain reaction and leptin by enzyme-linked immunosorbent assay. Statistical analyses included multiple linear regression, linear mixed effects, and Poisson regression models. Genotype AA carriers for the LEP-rs7799039 gene maintained a lower body weight throughout pregnancy compared with those with genotypes GG or GA + GG (β_AAvsGG = -7.91 kg; 95% confidence interval [CI], -14.21 to -1.61; P = .01; and β_{AAvsGA + GG} = -7.66 kg; 95% CI, -14.07 to -1.25; P = .02). The A allele was significantly associated with an increased risk for excessive GWG (relative risk_LEP-GAvsGG, 2.16; 95% CI, 1.23-3.80; and relative risk_LEP-AAvsGG, 2.37; 95% CI, 1.04-5.39). Neither the LEP-rs7799039 nor LEPR-rs1137101 SNP was significantly associated with pre-pregnancy overweight/obesity risk and leptin concentrations during pregnancy. In conclusion, our results indicate that women who had the AA genotype for LEP-rs7799039 displayed a lower body weight throughout pregnancy compared with GG or GA + GG carriers. LEP-rs7799039 was significantly associated with an increased risk for excessive GWG, but the results do not support significant associations of the LEP-rs7799039 and LEPR-rs1137101 polymorphisms with pre-pregnancy overweight/obesity risk and leptin concentrations throughout pregnancy.

Materno-foetal leptin and insulin-like growth factor in low birth weight neonates

Low birth weight (LBW) is a health concern in developing countries. Leptin and insulin-like growth factor-I (IGF-I) are factors that influence LBW. A case-control study was conducted at Medani hospital, Sudan. Cases were women who had LBW deliveries ( 2,500 g) and controls were women with normal-weight babies ( 2.500 – 4,000 g). Sociodemographic and obstetrical characteristics were gathered from both groups and leptin and IGF-I levels were measured by ELISA. Cases and controls (45 in each arm) were matched in their basic data. The median (interquartile) of maternal leptin levels [9.9 (1.9 – 21.8) vs. 16.0 (9.6 – 20.8), ng/ml; P0.001] and IGF-I [1.6 (0.7 – 20.0) vs. 6.1 (4.3 – 7.1) ng/ml ; P 0.001] were significantly lower in cases than in controls. Likewise, cord serum leptin [5.8 (2.1 – 12.6) vs. 20.0 (5.1 – 37.8) ng/ml; P0.001] and cord serum IGF-I [1.7 (1.3 – 2.0) vs. 6.9 (5.9 – 7.4) ng/ml; P0.001] levels were significantly lower in cases than in controls. Significant positive correlation was found between birth weight and cord leptin ( r0.398), maternal ( r0.795) and cord ( r0.863) IGF-I levels. Maternal and cord leptin and IGF-I levels were significantly lower in LBW babies.

The effects of hormones and physical exercise on hippocampal structural plasticity

The hippocampus plays an integral role in certain aspects of cognition. Hippocampal structural plasticity and in particular adult hippocampal neurogenesis can be influenced by several intrinsic and extrinsic factors. Here we review how hormones (i.e., intrinsic modulators) and physical exercise (i.e., an extrinsic modulator) can differentially modulate hippocampal plasticity in general and adult hippocampal neurogenesis in particular. Specifically, we provide an overview of the effects of sex hormones, stress hormones, and metabolic hormones on hippocampal structural plasticity and adult hippocampal neurogenesis. In addition, we also discuss how physical exercise modulates these forms of hippocampal plasticity, giving particular emphasis on how this modulation can be affected by variables such as exercise regime, duration, and intensity. Understanding the neurobiological mechanisms underlying the modulation of hippocampal structural plasticity by intrinsic and extrinsic factors will impact the design of new therapeutic approaches aimed at restoring hippocampal plasticity following brain injury or neurodegeneration.

Conjugated linoleic Acid supplementation during pregnancy and lactation reduces maternal high-fat-diet-induced programming of early-onset puberty and hyperlipidemia in female rat offspring

A maternal high-fat (HF) diet during pregnancy and lactation can result in adverse metabolic and reproductive outcomes in female offspring independent of postnatal diet. Interventions during critical windows of developmental plasticity may prevent developmental programming in offspring. The effects of maternal supplementation with the anti-inflammatory lipid conjugated linoleic acid (CLA) on early-onset puberty, metabolic dysfunction, and estrous cycle dysfunction was assessed. Sprague-Dawley rats were randomly assigned to a purified control diet (CD; 10% kcal from fat), CD with CLA (CLA; 10% kcal from fat, 1% CLA), HF (45% kcal from fat) or HF with CLA (HFCLA; 45% kcal from fat, 1% CLA). Diets were fed ad libitum for 10 days prior to time mating and throughout gestation and lactation. Offspring plasma/tissues were taken at Day 24 (prepubertal) or Day 150 (adult). Puberty was assessed from Day 26 and estrous cycle from Day 128. Female offspring from HF mothers had lower birth weights but by Postnatal Day 24 had exhibited catch-up growth concomitant with increased fat mass, hyperleptinemia, and dyslipidemia. Maternal CLA supplementation reversed these effects. Early-onset puberty was only observed in HF offspring; this was reversed in HFCLA offspring. In adulthood, despite no evidence of glucose intolerance or altered insulin sensitivity, HF offspring displayed increased fat mass, dyslipidemia, disrupted estrous cyclicity. and hyperleptinemia; this was reversed by maternal CLA supplementation. Data presented in this study demonstrate the importance of diet in women of reproductive age and during pregnancy on reproductive and metabolic parameters in their offspring and that supplementation with CLA during critical windows of development may represent a therapeutic strategy in the prevention of early-life programming of metabolic and reproductive dysfunction.

Association between follicular fluid leptin and serum insulin levels in nonoverweight women with polycystic ovary syndrome

Aims. We evaluated the links between leptin and visfatin levels and fertilization rates in nonoverweight (NOW) women with PCOS (NOW-PCOS) from Apulia undergoing in vitro fertilization/embryo transfer (IVF). Materials and Methodology. We recruited 16 NOW women with PCOS (NOW-PCOS) and 10 normally ovulating NOW women (control-NOW). All women underwent IVF. Androgens, 17-β-estradiol (17β-E₂), and insulin levels were measured in plasma and/or serum and leptin and visfatin levels were assayed in both serum and follicular fluid (FF-leptin, FF-visfatin). Results. In NOW-PCOS, both serum and FF-leptin were significantly lower than in control-NOW. In NOW-PCOS, significant correlations were found between BMI and serum leptin and insulinemia and FF-leptin. By contrast, in control-NOW, FF-leptin levels were not correlated with insulinemia. Serum visfatin levels were not significantly different in NOW-PCOS and control-NOW, but FF-visfatin levels were 1.6-fold higher, although not significantly, in NOW-PCOS than in control-NOW. Conclusions. Both serum leptin levels and FF-leptin are BMI- and insulin-related in Southern Italian NOW-PCOS from Apulia. In line with other reports showing that FF-leptin levels are predictive of fertilization rates, lower than normal FF-leptin levels in NOW-PCOS may explain their lower fertilization rate and this may be related to the level of insulin and/or insulin resistance.

Characterization of foamy epithelial surface cells in the canine endometrium

In mature bitches, endometrial epithelial surface cells modify function and corresponding morphology during the oestrous cycle. During late metoestrous, endometrial epithelial surface cells frequently accumulate fat and thereby adopt a foamy morphology. This cyclic appearance of foamy endometrial epithelial cells (fEECs) seems to be physiological in the dog, whereas in other species, it indicates pathological changes. Function of these fEECs has not been identified until now. Therefore, the aim of the study was to characterize the fEECs by means of transmission electron microscopy and immunohistochemistry. Different manifestations of fEECs were observed and analysed with regard to proliferative activity and presence of different epithelial adhesion molecules including PLEKHA7, β-catenin and E-cadherin. PLEKHA7 was restricted to the apical regions of the fEECs, whereas E-cadherin and β-catenin were demonstrated basolateral. The immunohistochemical detection of steroid hormone receptors demonstrated the responsiveness of the fEECs to steroid hormones. Intense progesterone receptor expression was observed in the fEECs indicating a high responsiveness to this hormone. Considering a potential function of the fEECs, we hypothesized that leptin, a hormone produced by other lipid-accumulating cells and described to be involved in reproduction, in particular during implantation, might also originate from the fEECs which was confirmed by immunohistochemical methods. Moreover, leptin receptor was found in fEECs indicating the fEECs as both, source and target for leptin. Therefore, we conclude that fEECs in the canine uterus have a potential role in early pregnancy events and that the different observed manifestations might simply reflect the variations of signs of pseudopregnancy among bitches.

Ghrelin and leptin pathophysiology in chronic kidney disease

Ghrelin is an orexigenic hormone with additional effects on the regulation of inflammation and the cardiovascular system. It may play an important role in the pathogenesis of cachexia/protein-energy wasting (PEW), inflammation and cardiovascular complications in chronic kidney disease (CKD). There are three circulating gene products of ghrelin, namely, acyl ghrelin, des-acyl ghrelin and obestatin, each with individual distinct functions. Perturbations of these circulating ghrelin proteins impact the overall milieu of CKD. Leptin is an anorexigenic hormone which is secreted from the adipocytes and interacts with ghrelin and other appetite-regulating hormones. Leptin also plays a role in regulating inflammation and the cardiovascular system. Indeed, ghrelin and leptin may play yin-and-yang roles in CKD pathophysiology. Clinical trials involving the use of the mimetics or antagonists of these hormones are limited to short-term phase I/II studies. Further understanding of their interactions in CKD pathophysiology is needed for potential large-scale clinical trials, which may impact the quality of life and survival of patients with CKD.

Plasma leptin concentrations during the reproductive cycle in the native Thai chicken (Gallus domesticus)

Plasma leptin concentrations were investigated during the reproductive cycle in the native Thai chicken. The plasma leptin concentration was high during non-laying (0.69±0.15ng/ml), lowered to a minimum concentration during egg laying (0.07±0.02ng/ml), and gradually increased during egg incubation and rearing of the chicks (0.53±0.22 and 0.74±0.29ng/ml, respectively). However, the differences were not significant. Incubating chickens that were deprived of their nests for 3 weeks showed a significant decrease in plasma leptin concentrations (0.29±0.04ng/ml, P<0.05) compared to those of their corresponding incubating controls (0.77±0.08ng/ml). Similarly, plasma leptin concentration of chickens that were deprived of their chicks for 4 weeks was significantly lower (0.09±0.11ng/ml, P<0.05), when compared to those of chickens that rearing their chicks (0.71±0.18ng/ml). These findings taken together with the results that the low plasma leptin concentrations were observed in chickens having relatively greater ovary and oviduct weights led to the suggestion that circulating leptin concentrations are associated with the reproductive states of the birds, especially the ovarian activity (i.e. ovarian steroid hormone concentrations) in the native Thai chicken, a tropical and continuous breeding species.

Integrative control of energy balance and reproduction in females

There is a strong association between nutrition and reproduction. Chronic dietary energy deficits as well as energy surpluses can impair reproductive capacity. Metabolic status impacts reproductive function at systemic level, modulating the hypothalamic GnRH neuronal network and/or the pituitary gonadotropin secretion through several hormones and neuropeptides, and at the ovarian level, acting through the regulation of follicle growth and steroidogenesis by means of the growth hormone-IGF-insulin system and local ovarian mediators. In the past years, several hormones and neuropeptides have been emerging as important mediators between energy balance and reproduction. The present review goes over the main sites implicated in the control of energy balance linked to reproductive success and summarizes the most important metabolic and neuroendocrine signals that participate in reproductive events with special emphasis on the role of recently discovered neuroendocrine peptides. Also, a little overview about the effects of maternal nutrition, affecting offspring reproduction, has been presented.

Effects of estradiol and FSH on leptin levels in women with suppressed pituitary

BACKGROUND

Female fertility depends on adequate nutrition and energy reserves, suggesting a correlation between the metabolic reserve and reproductive capacity. Leptin regulates body weight and energy homeostasis. The aim of this study was to investigate whether estradiol or FSH alone has a direct effect on the production of leptin.

METHODS

A total of 64 patients submitted to controlled ovarian hyperstimulation with recombinant FSH for assisted reproduction and 20 patients using estradiol valerate for endometrial preparation for oocyte donation treatment were included in the study. All patients used GnRH analogues before starting treatment to achieve pituitary suppression. Blood samples for hormonal measurements were collected before starting and after completing the respective treatments. Data were analyzed statistically by the chi-square test, Student's t-test and Pearson's correlation test.

RESULTS

We observed an elevation of serum leptin levels secondary to the increase in estradiol, in the absence of influence of any other ovarian or pituitary hormone. The rising rate of leptin levels was higher in women treated with recombinant FSH, which also had higher levels of estradiol, than in those treated with estradiol valerate.

CONCLUSIONS

This study demonstrates a correlation between serum levels of estradiol and leptin, suggesting that estradiol is an important regulator of leptin production and that its effects can be amplified by its association with FSH.

Adiponectin and reproduction

Adiponectin is an adipocyte-derived cytokine that acts as a major regulator of insulin sensitivity. Adiponectin deficiency can result in severe diabetes and metabolic disorders in humans. Since its discovery, our understanding of adiponectin's biological functions has expanded from insulin sensitization properties to new effects on inflammation, immunology, and human reproduction. Indeed, both obesity and excessive leanness are associated with reproductive dysfunction. The objective of this chapter is to review such biological actions and the potential roles of adiponectin on human reproduction. There is accumulative evidence for direct effects of this adipokine on the late stages of folliculogenesis and on the development of a functional placenta. In addition, clinical and genomic studies associate hypoadiponectinemia with pregnancy-related disorders, including polycystic ovarian syndrome.

Serum leptin levels in relation to circulating cytokines, chemokines, adhesion molecules and angiogenic factors in normal pregnancy and preeclampsia

OBJECTIVE

In this study, we determined circulating levels of C-reactive protein, several cytokines, chemokines, adhesion molecules and angiogenic factors along with those of leptin in healthy non-pregnant and pregnant women and preeclamptic patients, and investigated whether serum leptin levels were related to the clinical characteristics and measured laboratory parameters of the study participants.

METHODS

Sixty preeclamptic patients, 60 healthy pregnant women and 59 healthy non-pregnant women were involved in this case-control study. Levels of leptin and transforming growth factor (TGF)-beta1 in maternal sera were assessed by ELISA. Serum levels of interleukin (IL)-1beta, IL-1 receptor antagonist (IL-1ra), IL-2, IL-4, IL-6, IL-8, IL-10, IL-12p40, IL-12p70, IL-18, interferon (IFN)-gamma, tumor necrosis factor (TNF)-alpha, interferon-gamma-inducible protein (IP)-10, monocyte chemotactic protein (MCP)-1, intercellular adhesion molecule (ICAM)-1 and vascular cell adhesion molecule (VCAM)-1 were determined by multiplex suspension array. Serum C-reactive protein (CRP) concentrations were measured by an autoanalyzer. Serum total soluble fms-like tyrosine kinase-1 (sFlt-1) and biologically active placental growth factor (PlGF) levels were determined by electrochemiluminescence immunoassay. For statistical analyses, non-parametric methods were applied.

RESULTS

There were significant differences in most of the measured laboratory parameters among the three study groups except for serum IL-1beta and TGF-beta1 levels. Serum leptin levels were significantly higher in preeclamptic patients and healthy pregnant women than in healthy non-pregnant women. Additionally, preeclamptic patients had significantly higher leptin levels as compared to healthy pregnant women. Serum leptin levels were independently associated with BMI in healthy non-pregnant women. In healthy pregnant women, both BMI and serum CRP concentrations showed significant positive linear association with leptin levels. There were significant positive correlations between serum leptin concentrations of healthy pregnant women and systolic blood pressure, as well as serum levels of IP-10, while their serum leptin levels correlated inversely with fetal birth weight. In preeclamptic patients, a significant positive correlation was observed between serum concentrations of leptin and IP-10. Furthermore, elevated serum leptin level and sFlt-1/PlGF ratio had an additive (joint) effect in the risk of preeclampsia, as shown by the substantially higher odds ratios of their combination than of either alone.

CONCLUSIONS

Simultaneous measurement of leptin with several inflammatory molecules and angiogenic factors in this study enabled us to investigate their relationship, which can help to understand the role of circulating leptin in normal pregnancy and preeclampsia.

Abnormal spiral artery remodelling in the decidual segment during pregnancy: from histology to clinical correlation

INTRODUCTION

Modification of the spiral arteries with loss of the muscular vascular wall, invaded by the trophoblasts, represents the goal of the physiological vascular adaptation during human implantation. When physiological vascular changes do not occur, an unfavourable evolution of gestation may develop as suggested by uterine biopsies studies.

AIMS

To evaluate the prevalence of the abnormal spiral arteries modification (ASAM) through the routine examination of placentas, to identify maternal predisposing factors and to examine the correlations between the histological lesion and pregnancy outcome.

METHODS

1534 consecutive singleton pregnancies were retrospectively analysed. An extensive histological and clinical investigation was performed.

RESULTS

ASAM was present in 5.8% pregnancies. When compared with cases without ASAM, cases with ASAM exhibited a higher prevalence of pre-eclampsia (10% vs 2%), placental abruption (5.5% vs 0.3%), preterm premature rupture of membranes (7% vs 1.3%) and intrauterine fetal death (18% vs 2.2%). Multivariate analysis showed that the maternal body mass index represents the major maternal pregestational factor that can influence the prevalence of ASAM (OR=1.8, 95% CI 1.1 to 3 in cases with BMI>30 kg/m(2)).

CONCLUSION

The abnormal modification of the decidual segment of the spiral arteries is identifiable at the time of the conventional histopathological placental evaluation and is associated with adverse pregnancy outcome. The identification of the cause of the unfavourable evolution of pregnancy is fundamental for parents, both for counselling and for prevention; the identification of ASAM in such pregnancies might provide additional valuable information.

Altered contribution of RhoA/Rho kinase signaling in contractile activity of myometrium in leptin receptor-deficient mice

In late gestation, enhanced myometrial contractility is mediated in part through increased Rho/Rho kinase. Since leptin, which is elevated in pregnancy and obesity, can directly depress myometrial function, we hypothesized that in leptin receptor-deficient mice, myometrial contractility would be greater in late pregnancy due to increased Rho/Rho kinase activity. To test this, we correlated RhoA and Rho kinase expression to contractility in myometrium from nonpregnant (NP) and late-pregnant (P18) heterozygous leptin receptor-deficient mice (db/+) vs. wild-type (WT) mice. In NP mice, KCl-induced contractions were similar between WT and db/+ myometrium. However, the Rho kinase-dependent component of the contractions was greater in db/+ mice, along with an increased expression of Rho kinase. KCl-induced contractions increased in strength in myometrium from P18 WT and db/+ compared with NP. Although the contribution of Rho kinase to contractions was unchanged in P18 WT mice, it was decreased in P18 db/+ mice. The decrease in Rho kinase-dependent contractions in P18 db/+ mice coincided with reduced RhoA and Rho kinase expression relative to NP db/+. Addition of high-fat-induced abnormal glucose utilization prevented changes in Rho kinase function. We conclude that abnormal leptin signaling increases expression and function of Rho kinase to maintain contractile function in NP myometrium and that during pregnancy the contribution of RhoA and Rho kinase expression to myometrial function is reduced despite an increase in myometrial contractility. Thus, other signaling mechanisms appear to compensate when leptin signaling is reduced to maintain contractile function during pregnancy.

Expression of peroxisome proliferator-activated receptor isoforms in the rat uterus during early pregnancy

Peroxisome proliferator-activated receptors (PPARs) play an important role in different compartments of the female reproductive system in rodents and humans. However, expressional profiles and physiological functions of PPARs in the endometrium prior to the placentation are not well understood. In this study, we determined expressional profiles of the PPARs during early pregnancy. Immunocytochemistry revealed that both PPARα and PPARβ/δ were strongly detected in the endometrial stroma on days 4.5-6.5 of pregnancy, which is just a starting time of implantation. Delayed implantation animal model showed that the expressions of PPARα and PPARβ/δ occurred after the initiation of implantation in the endometrial stroma. Moreover, an in vitro decidualization model further revealed that the expression of PPARα increased in the cultured rat endometrial stromal cells at 24 h after the decidualization treatment, but the expression of PPARβ/δ was delayed and increased at 48 h after the treatment. PPARγ was expressed in the endometrial stroma and its expression decreased significantly at 2.5 days post-coitum and maintained a low level of expression during the period of implantation. These results indicate that PPARα is expressed and induced by the initiation of implantation, prior to the expression of PPARβ/δ in decidualized endometrium. Increasing expression of PPARγ during fertilization and its decline during the period of implantation further suggest that PPARs may play important roles during early pregnancy.

PPARs and Female Reproduction: Evidence from Genetically Manipulated Mice

Peroxisome proliferator-activated receptors (PPARs) are ligand-activated nuclear receptors controlling many important physiological processes, including lipid and glucose metabolism, energy homeostasis, inflammation, as well as cell proliferation and differentiation. In the past decade, intensive study of PPARs has shed novel insight into prevention and treatment of dyslipidemia, insulin resistance, and type 2 diabetes. Recently, a large body of research revealed that PPARs are also functionally expressed in reproductive organs and various parts of placenta during pregnancy, which strongly suggests that PPARs might play a critical role in reproduction and development, in addition to their central actions in energy homeostasis. In this review, we summarize recent findings elucidating the role of PPARs in female reproduction, with particular focus on evidence from gene knockout and transgenic animal model study.

Differentially expressed genes in early gestational chorionic villi after administration of mifepristone

To investigate the effect of mifepristone on gene expression of human chorionic villi in early pregnancy, nine women were recruited into a randomised controlled trial. All subjects were healthy women who had regular menstrual cycles and sought termination of pregnancy up to 40 days gestational age. In the test group, gestational sacs were taken by vacuum aspiration of the uterus 24 h after a single dose of 150 mg mifepristone was administered. Chorionic villi were collected and frozen in liquid nitrogen. The control samples were collected using the same method from the women without administration of mifepristone. The gene expressions of villus were monitored by human cDNA microarrays. It is found that the expressions of 262 transcripts were significantly altered in the test group. Gene ontology and pathways analyses were conducted to further analyse these genes. Many of these genes are known to play potentially an important role in the placentation and the molecular regulation of maternal-fetal interface. Therefore, it is suggested that the placental development and microenvironment of the maternal-fetal interface were interfered by administration of mifepristone. These data provide insight into the molecular mechanism about medical abortion induced by mifepristone.

Extra- and intra-ovarian factors in polycystic ovary syndrome: impact on oocyte maturation and embryo developmental competence

BACKGROUND

Polycystic ovary syndrome (PCOS) is a common metabolic dysfunction and heterogeneous endocrine disorder in women of reproductive age. Although patients with PCOS are typically characterized by increased numbers of oocytes retrieved during IVF, they are often of poor quality, leading to lower fertilization, cleavage and implantation rates, and a higher miscarriage rate.

METHODS

For this review, we searched the database MEDLINE (1950 to January 2010) and Google for all full texts and/or abstract articles published in English with content related to oocyte maturation and embryo developmental competence.

RESULTS

The search showed that alteration of many factors may directly or indirectly impair the competence of maturating oocytes through endocrine and local paracrine/autocrine actions, resulting in a lower pregnancy rate in patients with PCOS. The extra-ovarian factors identified included gonadotrophins, hyperandrogenemia and hyperinsulinemia, although intra-ovarian factors included members of the epidermal, fibroblast, insulin-like and neurotrophin families of growth factors, as well as the cytokines.

CONCLUSIONS

Any abnormality in the extra- and/or intra-ovarian factors may negatively affect the granulosa cell-oocyte interaction, oocyte maturation and potential embryonic developmental competence, contributing to unsuccessful outcomes for patients with PCOS who are undergoing assisted reproduction.

Evolution of leptin structure and function

Leptin, the protein product of the obese(ob or Lep) gene, is a hormone synthesized by adipocytes that signals available energy reserves to the brain, and thereby influences development, growth, metabolism and reproduction. In mammals, leptin functions as an adiposity signal: circulating leptin fluctuates in proportion to fat mass, and it acts on the hypothalamus to suppress food intake. Orthologs of mammalian Lep genes were recently isolated from several fish and two amphibian species, and here we report the identification of two Lep genes in a reptile, the lizard Anolis carolinensis. While vertebrate leptins show large divergence in their primary amino acid sequence, they form similar tertiary structures, and may have similar potencies when tested in vitro on heterologous leptin receptors (LepRs). Leptin binds to LepRs on the plasma membrane, activating several intracellular signaling pathways. Vertebrate LepRs signal via the Janus kinase (Jak) and signal transducer and activator of transcription (STAT) pathway. Three tyrosine residues located within the LepR cytoplasmic domain are phosphorylated by Jak2 and are required for activation of SH2-containing tyrosine phosphatase-2, STAT5 and STAT3 signaling. These tyrosines are conserved from fishes to mammals, demonstrating their critical role in signaling by the LepR. Leptin is anorexigenic in representatives of all vertebrate classes, suggesting that its role in energy balance is ancient and has been evolutionarily conserved. In addition to its integral role as a regulator of appetite and energy balance, leptin exerts pleiotropic actions in development, physiology and behavior.

Obesity and polycystic ovary syndrome: association with androgens, leptin and its genotypes

Obesity and hyperandrogenaemia are key features of polycystic ovary syndrome (PCOS). The aim of this study was to investigate whether leptin and androgens are associated with obesity in PCOS subjects and identify whether there exist any genetic alterations in leptin gene in women with PCOS. The results reveal that leptin levels are elevated in women with PCOS and associate with BMI. However, irrespective of the obesity status leptin levels are higher in PCOS cases indicating that increased BMI/obesity may not be the only factor contributing to elevated levels of leptin. With regard to testosterone and androstenedione, the levels were increased in obese individuals irrespective of PCOS status. No correlation between leptin and androstenedione or testosterone was observed in controls and PCOS subjects. The single-nucleotide polymorphism G19A detected in the untranslated exon 1 of leptin gene was not associated with PCOS and does not contribute to elevated levels of leptin. The results overall suggest that androgen and leptin levels are increased in PCOS and obesity. It demonstrates that obesity is a confounding factor for hyperandrogenaemia irrespective of their PCOS status. The study rules out role of obesity status and leptin genotype in increase in leptin levels observed in PCOS cases.

Influence of leptin on in vitro maturation and steroidogenic secretion of cumulus–oocyte complexes through JAK2/STAT3 and MEK 1/2 pathways in the rabbit model

Extreme body mass indexes may impair reproductive outcome in assisted reproductive technologies. Leptin reflects the amount of body fat and could act as a modulator of oocyte quality through activation of specific transcription factors. The aim of this work was to establish whether: 1) leptin influences meiotic and cytoplasmic oocyte maturation; 2) STAT3 and MAPK mediate the effects of leptin and 3) leptin modulates steroid secretion by cumulus–oocyte complexes (COC) duringin vitromaturation (IVM). We confirmed immunolocalisation of leptin receptor in oocytes, cumulus/granulosa cells during the peri-ovulatory period. The confocal study showed that COC supplemented with 1, 10 and 100 ng/ml leptin had a significantly higher metaphase II (MII) percentage than those IVM without leptin (P<0.05) and a similar MII index compared to the group supplemented with 10% FCS. Leptin did not increase the percentage of cytoplasmically matured oocytes in terms of cortical granule migration rate, whereas a significantly higher index was found in the FCS group (P<0.001). Oestradiol concentrations in spent media were higher in the FCS group compared to other treatments (P<0.001). Leptin-stimulated nuclear oocyte maturation was significantly impaired when leptin-induced JAK2/STAT3 and MEK 1/2 activation was suppressed by the inhibitors (P<0.001). Steroid secretion of COC was not affected by leptin activation of JAK2/STAT3 or MEK 1/2 pathways. In conclusion, JAK2/STAT3 and MEK 1/2 pathways mediate the enhancement of nuclear oocyte maturation by leptin; however, neither cytoplasmic oocyte maturation nor steroidogenic response of COC were improved in the present rabbit model.

Association of insulin resistance with anti-Mullerian hormone levels in women without polycystic ovary syndrome (PCOS)

OBJECTIVE

To explore the relationship of insulin resistance (IR) and adipokines (leptin, adiponectin, RBP4) to anti-Mullerian hormone (AMH) levels in women without polycystic ovary syndrome (PCOS).

DESIGN/PATIENTS/MEASUREMENTS

We recruited 120 healthy, reproductive age women without PCOS. An overnight fasting blood draw, anthropometric measurements, analyses of serum levels of AMH, adipokines (leptin, adiponectin and RBP4) and total testosterone, a homeostasis model assessment for insulin resistance (HOMA-IR) and a transvaginal ultrasound scan were performed between the third and fifth day of their spontaneous menstrual cycles.

RESULTS

Higher HOMA-IR levels were associated with lower levels of AMH. After adjustment for age, serum AMH levels negatively correlated with insulin, fasting glucose, HOMA-IR and RBP4. However, a positive correlation was identified between serum AMH and adiponectin. A final multiple stepwise linear regression demonstrated that HOMA-IR was independently associated with AMH.

CONCLUSION

An independent relationship exists between HOMA-IR and AMH in women without PCOS, possibly due to the effect of abnormal insulin action on AMH secretion by granulosa cells.

Retinol-binding protein 4 in polycystic ovary syndrome--association with steroid hormones and response to pioglitazone treatment

CONTEXT

Polycystic ovary syndrome (PCOS) is frequently associated with insulin resistance.

OBJECTIVE

The aim of the study was to investigate a putative role of the adipokines retinol-binding protein 4 (RBP4), adiponectin, and visfatin in a cohort of patients with PCOS and their response to treatment with pioglitazone.

DESIGN AND SETTING

We conducted a randomized, controlled, double-blind study at a tertiary referral center.

PATIENTS AND INTERVENTIONS

Forty premenopausal women with PCOS were allocated to receive treatment with either pioglitazone (30 mg/d) or a placebo for a period of 3 months.

MAIN OUTCOME MEASURES

Serum concentrations of RBP4, adiponectin, and visfatin were determined along with metabolic and hormonal parameters before and after treatment.

RESULTS

Serum adiponectin concentrations were higher after treatment with pioglitazone (P = 0.003), whereas RBP4 levels tended to decrease (P = 0.06), and visfatin concentrations remained unchanged. We found RBP4 serum concentrations at baseline to be positively correlated with serum levels of testosterone (R = 0.446; P = 0.005), 17-OH progesterone (R = 0.345, P = 0.037), and dehydroepiandrosterone sulfate (R = 0.347; P = 0.041). However, these correlations were abolished after treatment with pioglitazone. Patients with high RBP4 levels had significantly higher hirsutism scores (P = 0.038 before and P = 0.034 after treatment). In contrast, serum adiponectin concentrations were related to parameters of impaired glucose metabolism, and no significant associations were detected for visfatin.

CONCLUSIONS

Our results suggest that RBP4 may contribute to endocrine changes and to the phenotypic manifestation of patients with PCOS because higher RBP4 concentrations are associated with higher androgen levels and higher clinical hirsutism scores independently of pioglitazone treatment. The molecular involvement of RBP4 in human steroid metabolism requires further clarification.

Leptin affects system A amino acid transport activity in the human placenta: evidence for STAT3 dependent mechanisms

BACKGROUND

Amino acids are important nutrients during fetal development, and the activity of placental amino acid transporters is crucial in the regulation of fetal growth. Leptin, an adipocyte- and placenta-derived hormone, has been proposed to act as a peripheral signal in reproduction in humans. Leptin is elevated during pregnancy and elevated further in pathologic pregnancies such as preeclampsia. However, the role of leptin in placental function has not been fully elucidated. We hypothesize that leptin plays a role in the regulation of placental amino acid transport by activation of the JAK-STAT pathway.

METHODS

Placental amino acid transport, specifically system A transport was studied in placental villous fragments using the amino acid analog, methylaminoisobutyric acid (MeAIB). Specific inhibitors of the JAK-STAT signal transduction pathway were used to further elucidate their role in leptin-mediated effects on amino acid transport activity. Western blotting was performed to identify STAT3 phosphorylation as a measure of leptin receptor activation.

RESULTS

Leptin significantly increased system A amino acid transporter activity by 22-42% after 1h of incubation. Leptin activated JAK-STAT signaling pathway as evidenced by STAT3 phosphorylation, and inhibition of STAT3 or JAK2 resulted in 36-45% reduction in system A amino acid transporter activity. Furthermore, blocking endogenously produced leptin also decreased system A transport by 45% comparable to STAT3 inhibition.

CONCLUSIONS

These data demonstrate that leptin stimulates system A by JAK-STAT dependent pathway in placental villous fragments. Our findings support the autocrine/paracrine role of leptin in regulating amino acid transport in the human placenta.

Developmental changes in the relationship between leptin and adiposity among Tsimané children and adolescents

Leptin is thought to signal energy stores, thus helping the body balance energy intake and expenditure. However, the strong relationship between leptin and adiposity in populations with adequate nutrition or common obesity is not universal across ecologic contexts, and leptin often correlates only weakly, or not at all, with adiposity in populations of lean or marginally-nourished males. To clarify whether the relationship between adiposity and leptin changes during development, this study examines leptin and body fat among children and adolescents of lowland Bolivia. Anthropometric measures of body composition and dried blood spot samples were collected from 487 Tsimane' ranging from 2 to 15 years of age. Leptin was assayed using an enzyme immunoassay protocol validated for use with blood spot samples. In this population, leptin concentrations were among the lowest reported in a human population (mean +/- SD: 1.26 +/- 0.5 and 0.57 +/- 0.3 in females and males). In addition, the relationship between leptin and adiposity follows distinct developmental trajectories in males and females. In males, leptin is weakly correlated with most measures of body composition at all ages investigated. However, in females, the level of body fat and the strength of the correlation between body fat and leptin (a measure of its strength as a signal of energy stores) both increase markedly with age. These findings suggest a more important role of leptin as a signal of energy stores among females as they approach reproductive maturity, while raising questions about the function of this hormone in lean males.

Different physiological roles of serum leptin in the regulation of energy intake and thermogenesis between pregnancy and lactation in primiparous Brandt's voles (Lasiopodomys brandtii)

Reproduction, especially lactation, is associated with major metabolic adaptive changes. In this study, we investigated the metabolic changes and the roles of leptin during different periods of reproduction in primiparous Brandt's voles (Lasiopodomys brandtii). Energy intake, thermogenic capacity and serum leptin levels were examined in non-reproductive, mid pregnant, late pregnant, early lactating and peak lactating voles. Voles increased body mass by nearly 70% during late pregnancy compared to the non-breeding controls. The increase in body mass was mainly due to the increase in body fat mass which increased by 56%, and the growth of the reproductive tissues and digestive organs. Lactating voles decreased body fat by nearly 27% at peak lactation compared to the controls, and 53% compared to late pregnant voles. At the same time they increased food intake significantly. Uncoupling protein 1 (UCP1) content in brown adipose tissue (BAT) decreased significantly at peak lactation. Serum leptin increased significantly in the mid pregnancy, at a time when there was no increase in body fat, and remained at this high level in late pregnancy. Leptin levels decreased after parturition and reached a nadir at peak lactation. Serum leptin was negatively correlated with energy intake during lactation, but not during pregnancy. These data suggest that Brandt's voles adjust energy intake, thermogenic capacity and body reserves to match the high energy demands for reproduction. Hyperleptinemia, without decreased energy intake suggests a state of leptin resistance during pregnancy, and hypoleptinemia during lactation might act as a signal to stimulate energy intake.

Hormonal regulation of hippocampal dendritic morphology and synaptic plasticity

The peripheral functions of hormones such as leptin, insulin and estrogens are well documented. An important and rapidly expanding field is demonstrating that as well as their peripheral actions, these hormones play an important role in modulating synaptic function and structure within the CNS. The hippocampus is a major mediator of spatial learning and memory and is also an area highly susceptible to epileptic seizure. As such, the hippocampus has been extensively studied with particular regard to synaptic plasticity, a process thought to be necessary for learning and memory. Modulators of hippocampal function are therefore of particular interest, not only as potential modulators of learning and memory processes, but also with regard to CNS driven diseases such as epilepsy. Hormones traditionally thought of as only having peripheral roles are now increasingly being shown to have an important role in modulating synaptic plasticity and dendritic morphology. Here we review recent findings demonstrating that a number of hormones are capable of modulating both these phenomena.

Relationships among changes of serum leptin concentration, leptin mRNA expression in white adipose tissue (WAT), and WAT fat-cell size in female Japanese black bears (Ursus thibetanus japonicus)

As a first step to study the relationship between fat accumulation and reproductive success in Japanese black bears ( Ursus thibetanus japonicus Schlegel, 1857) with the focus on leptin, we determined leptin cDNA sequences in the bears. Next, we studied the possibility of white adipose tissue (WAT) as a leptin secretion source by observing the changes of leptin mRNA expression in WAT by semiquantitative real-time reverse transcript – polymerase chain reaction, the index of WAT fat-cell size, and serum leptin concentration in pregnant bears. Then, based on our results, we discussed roles of leptin in those bears. The amino acid sequences of leptin from the bears were highly identical to that of other carnivores. The expression of leptin mRNA in WAT was detected from September to January, with a tendency to increase in late November and January; the relationship between changes in the index of WAT fat-cell size and those in serum leptin concentration was high (r = 0.55, P < 0.01), with an increase in both in mid-November. These results suggested that leptin was mainly secreted from WAT in bears and that serum leptin concentrations might reflect their nutritional condition. Moreover, leptin might serve as an indicator of their fat mass, which would affect their survival during hibernation and their reproductive success.

The secretory function of adipocytes in the physiology of white adipose tissue

White adipose tissue, previously regarded as a passive lipid storage site, is now viewed as a dynamic tissue. It has the capacity to actively communicate by sending and receiving different types of signals. An overview of these signals, the external modulators that affect adipose tissue and the secreted signaling molecules, the adipokines, is presented. The secretory function is highlighted in relation to energy metabolism, inflammation and the extracellular matrix and placed in the context of adipose tissue biology. We observe that the endocrine function of adipocytes receives much attention, while its paracrine and autocrine functions are underestimated. Also, we provide examples that species specificity should not be neglected. We conclude that adipose tissue primarily is an energy storage organ, well supported by its secretory function.

Assessing the role of endometrial alteration among obese patients undergoing assisted reproduction

Obesity seems to exert a small but important extraovarian effect that may influence cycle outcome during assisted reproduction. Future investigation should focus on elucidating whether the endometrium is truly responsible for this deficit, and if it is, determining the mechanisms involved.

Decreased clearance of serum retinol-binding protein and elevated levels of transthyretin in insulin-resistant ob/ob mice

Serum retinol-binding protein (RBP4) is secreted by liver and adipocytes and is implicated in systemic insulin resistance in rodents and humans. RBP4 normally binds to the larger transthyretin (TTR) homotetramer, forming a protein complex that reduces renal clearance of RBP4. To determine whether alterations in RBP4-TTR binding contribute to elevated plasma RBP4 levels in insulin-resistant states, we investigated RBP4-TTR interactions in leptin-deficient ob/ob mice and high-fat-fed obese mice (HFD). Gel filtration chromatography of plasma showed that 88-94% of RBP4 is contained within the RBP4-TTR complex in ob/ob and lean mice. Coimmunoprecipitation with an RBP4 antibody brought down stoichiometrically equal amounts of TTR and RBP4, indicating that TTR was not more saturated with RBP4 in ob/ob mice than in controls. However, plasma TTR levels were elevated approximately fourfold in ob/ob mice vs. controls. RBP4 injected intravenously in lean mice cleared rapidly, whereas the t(1/2) for disappearance was approximately twofold longer in ob/ob plasma. Urinary fractional excretion of RBP4 was reduced in ob/ob mice, consistent with increased retention. In HFD mice, plasma TTR levels and clearance of injected RBP4 were similar to chow-fed controls. Hepatic TTR mRNA levels were elevated approximately twofold in ob/ob but not in HFD mice. Since elevated circulating RBP4 causes insulin resistance and glucose intolerance in mice, these findings suggest that increased TTR or alterations in RBP4-TTR binding may contribute to insulin resistance by stabilizing RBP4 at higher steady-state concentrations in circulation. Lowering TTR levels or interfering with RBP4-TTR binding may enhance insulin sensitivity in obesity and type 2 diabetes.

Association of serum and follicular fluid leptin concentrations with granulosa cell phosphorylated signal transducer and activator of transcription 3 expression in fertile patients with polycystic ovarian syndrome

OBJECTIVE

Our objective was to evaluate whether polycystic ovarian syndrome (PCOS)-associated infertility is related to alterations of leptin, leptin receptor (Ob-R), and the phosphorylated signal transducer and activator of transcription 3 (p-STAT3)/suppressor of cytokine signal 3 (SOCS3) system in the ovary.

DESIGN AND SETTING

A case-control study was conducted in a university hospital.

PATIENTS

Thirty-one infertile PCOS women with oligoovulation plus polycystic ovarian morphology and 79 infertile women with tubal blockage (control) participated in the study. The subjects were stratified according to in vitro fertilization outcomes: successful and failed subgroups.

METHODS

Serum and follicular fluid (FF) leptin levels were measured with ELISA. RT-PCR and Western blotting were performed to assess expression of mRNA encoding leptin and Ob-R and proteins of p-STAT3 and SOCS3 in granulosa cells (GCs).

RESULTS

Leptin levels in serum and FF of PCOS women were significantly higher than those of control (P < 0.01). There were no significant differences in expression of leptin mRNA and short and long Ob-Rs between PCOS and control (P > 0.05). The p-STAT3 level was decreased in PCOS compared with control (P < 0.01), whereas SOCS3 remained significantly unchanged (P > 0.05). Further analysis showed that serum and FF leptin levels were significantly higher, whereas p-STAT3 in GCs was lower in the failed subgroup of PCOS than those in the successful subgroup of PCOS (P < 0.05).

CONCLUSION

Hyperleptinemia and high FF leptin are important pathologies of PCOS with infertility. Lower levels of p-STAT3 in GCs may be related to ovarian leptin resistance and fecundity in PCOS women. Relatively high serum and FF leptin and low p-STAT3 in GCs may account for decreased fertilization, implantation, and pregnancy rates of in vitro fertilization in PCOS women.

Effects of leptin supplementation in in vitro maturation medium on meiotic maturation of oocytes and preimplantation development of parthenogenetic and cloned embryos in pigs

The objective of the present study was to investigate the effects of leptin addition in in vitro maturation (IVM) medium on meiotic maturation of oocytes and preimplantation development of parthenogenetic and cloned embryos in pigs. In experiment 1, oocytes were matured in North Carolina State University 23 (NCSU-23) medium supplemented with various concentrations of leptin: 0, 1, 10 and 100 ng/ml. IVM medium added with 10 or 100 ng/ml leptin significantly increased the rate of oocytes reaching metaphase II compared to the control (76.8% and 73.8% versus 61.7%). In experiment 2, the influence of the timing of leptin addition in IVM medium on meiotic maturation of porcine oocytes was assessed, and maximum maturation rate of oocytes developing to metaphase II was achieved when supplemented during the first half (0-22 h), the latter half (22-44 h) or the entire maturation period (0-44 h) compared to the control (80.5%, 84.7% and 78.1% versus 70.4%). In experiment 3, leptin strikingly increased the blastocyst rate of parthenogenetic embryos at the concentration of 10 ng/ml (37.5% versus 21.7%) and this increase was independent of the addition timing (0-44, 0-22, 22-44 h) compared to the control (32.5%, 34.6% and 31.5% versus 16.2%). Moreover, total cell number per blastocyst of parthenogenetic embryos was obviously increased in the 10 and 100 ng/ml leptin treatments as compared with the control (36, 38 versus 28). In experiment 4, 10 ng/ml leptin treatment significantly increased the rate of cleavage (72% versus 56%) of cloned embryos. Meanwhile, the rate of blastocyst formation was also improved although no significant difference was found (12.8% versus 7.1%). Collectively, our results indicate that leptin supplementation in IVM medium may be beneficial not only for developmental potential of oocytes but for subsequent developmental competence of embryos produced by parthenogenetic activation and the cleavage of embryos derived by somatic cell nuclear transfer (SCNT).

Role of leptin and ghrelin in the regulation of gonadal function

Gonadal development and function is sustained by the complex interaction of an array of regulatory signals that operate directly on the gonads and/or indirectly via modulation of gonadotropin secretion. During the last decade, different factors primarily involved in the control of food intake and energy balance have been demonstrated as putative modulators of different elements of the reproductive axis, including the gonads, thus helping to define the neuroendocrine basis for the link between body energy stores and fertility. These factors include not only the adipocyte-derived hormone leptin, which is indispensable for proper energy balance and reproduction, but also a number of neuropeptides and hormones of central and peripheral origin. In the latter, growing evidence strongly suggests the involvement of the stomach-secreted peptide ghrelin in the control of several aspects of gonadal function. Interestingly, leptin and ghrelin have been proposed as reciprocally related regulators of energy homeostasis; however, their potential interplay in the control of reproduction remains ill defined. This work will summarize the most salient findings concerning the potential roles of leptin and ghrelin in the functional control of the gonads. In addition, open issues regarding the reproductive facets of these metabolic signals will be highlighted. Overall, the authors propose that through complementary or antagonistic actions, leptin and ghrelin may jointly cooperate to modulate a wide set of reproductive functions, thereby contributing to the physiologic integration of energy balance and reproduction.