Direct effects of leptin and adiponectin on peripheral reproductive tissues: a critical review

Tetrahydrocurcumin alleviates di-(2-ethylhexyl) phthalate-induced adipose tissue dysfunction and testicular toxicity in adult mice: possible involvement of adiponectin-adipoR signaling in the testis

Widespread exposure to endocrine disruptors is associated with metabolic dysfunction and reproductive toxicity. Tetrahydrocurcumin (THC) has attracted attention as it offers protection against obesity and metabolic disorders due to its potent antioxidative and diverse biological properties but its influence and underlying mechanism of action on adipose tissue function and DEHP-induced testicular injury remain unknown. Our results showed that THC (100 mg kg-1 day-1) administration for 27 weeks enlarged adipocytes while attenuating macrophage infiltration and IL-6 expression in the adipose tissue of male C57BL/6J mice exposed to 5 mg kg-1 day-1 of DEHP. Moreover, THC ameliorated DEHP-induced deregulation of adiponectin but not leptin. DEHP caused testicular histological damage, spermatogenesis impairment, apoptosis, inflammation, and AGE, which were improved by THC. THC treatment elevated Nrf2/HO-1 and decreased Glut1 in interstitial Leydig cells, which may contribute to its beneficial effects on the testis. Our results further demonstrated that THC also ameliorated circulating adiponectin and testicular adipoR1-AMPK signaling, partially accounting for the improvement of DEHP-caused testicular dysfunction. The finding of this study revealed that THC is a promising candidate for improving adipose and testicular dysfunction caused by DEHP.

Replacement Nellore heifers receiving supplementation under different herbage allowance: effects on forage characteristics, performance, physiology, and reproduction

In Brazil, heifers typically calve at 36-48 months. Due to the high demand for meat and the need to reduce slaughter age, high supplementation has become commonly used in beef cattle farming. However, the literature remains scarce on studies that explore the impact of grazing management during the background phase on the productivity and reproductive efficiency of young Nellore heifers. This study aimed to evaluate the effects of two-herbage allowances (HA) on forage characteristics, performance, physiology and reproductive parameters of replacement Nellore heifers. Ninety weaned heifers [169 ± 19 kg of shrunk body weight (SBW); 210 ± 28 days of age] were blocked by initial BW and randomly assigned to receive different HA: (1) High herbage allowance (HHA: 7.2 kg DM/kg BW) and (2) Low herbage allowance (LHA: 3.3 kg DM/kg BW); and divided into six paddocks, totaling 12 paddocks. The experimental period was divided into the growing phase (D173) and the reproductive season (D83). Continuous stocking with a variable stocking rate was used. The supplement was provided daily with expected intake of around 10 g/kg of BW. The HHA pasture showed greater values of canopy height, greater HA, and lower values of CP and CP: in vitro digestible DM ratio than the LHA pasture over the days of the study (P ≤ 0.05). Herbage mass and the green stem proportion were lower in LHA pasture (P < 0.01), while the green leaf (g/kg DM) and senescent stem proportions (g/kg DM) were higher (P = 0.080) when compared to HHA pasture. Heifers maintained on HHA pasture had a higher average daily gain (P < 0.01), forage intake (P < 0.003), higher SBW (P < 0.01), Longissimus area (P < 0.01), and 12th-rib fat thickness (P < 0.01) than those kept in the LHA pasture. The proportion of heifers that reached the weight at maturity on D173 (P = 0.027) and the proportion of pubertal pregnancy heifers (P = 0.042) were greatest in the HHA treatment. The blood urea nitrogen (P = 0.002) was higher in heifers maintained in the LHA pasture. Heifers maintained in HHA pasture showed higher values of relative abundance of mRNA for UGT1A6 (P = 0.004) and IGFBP3 (P = 0.072). The use of HHA criteria increased forage intake, body gain, and carcass attributes of animals, which led to better reproductive performance of Nellore heifers.

The Impact of the Endocrine and Immunological Function of Adipose Tissue on Reproduction in Women with Obesity

Obesity, which leads to metabolic dysregulation and body function impairment, emerges as one of the pressing health challenges worldwide. Excessive body fat deposits comprise a dynamic and biologically active organ possessing its own endocrine function. One of the mechanisms underlying the pathophysiology of obesity is low-grade systemic inflammation mediated by pro-inflammatory factors such as free fatty acids, lipopolysaccharides, adipokines (including leptin, resistin and visfatin) and cytokines (TNF-α, IL-1β, Il-6), which are secreted by adipose tissue. Together with obesity-induced insulin resistance and hyperandrogenism, the exacerbated immune response has a negative impact on the hypothalamic-pituitary-gonadal axis at all levels and directly affects reproduction. In women, it results in disrupted ovarian function, irregular menstrual cycles and anovulation, contributing to infertility. This review focuses on the abnormal intracellular communication, altered gene expression and signaling pathways activated in obesity, underscoring its multifactorial character and consequences at a molecular level. Extensive presentation of the complex interplay between adipokines, cytokines, immune cells and neurons may serve as a foundation for future studies in search of potential sites for more targeted treatment of reproductive disorders related to obesity.

Obesity and male fertility disorders

Often associated with obesity, male infertility represents a widespread condition that challenges the wellbeing of the couple. In this article, we provide a comprehensive and critical analysis of studies exploring the association between obesity and male reproductive function, to evaluate the frequency of this association, and establish the effects of increased body weight on conventional and biofunctional sperm parameters and infertility. In an attempt to find possible molecular markers of infertility in obese male patients, the numerous mechanisms responsible for infertility in overweight/obese patients are reviewed in depth. These include obesity-related functional hypogonadism, insulin resistance, hyperinsulinemia, chronic inflammation, adipokines, irisin, gut hormones, gut microbiome, and sperm transcriptome. According to meta-analytic evidence, excessive body weight negatively influences male reproductive health. This can occurr through a broad array of molecular mechanisms. Some of these are not yet fully understood and need to be further elucidated in the future. A better understanding of the effects of metabolic disorders on spermatogenesis and sperm fertilizing capacity is very useful for identifying new diagnostic markers and designing therapeutic strategies for better clinical management of male infertility.

The Molecular Basis of Male Infertility in Obesity: A Literature Review

The rising incidence of obesity has coincided with rising levels of poor reproductive outcomes. The molecular basis for the association of infertility in obese males is now being explained through various mechanisms. Insulin resistance, hyperglycemia, and changes in serum and gonadal concentrations of adipokines, like leptin, adiponectin, resistin, and ghrelin have been implicated as causes of male infertility in obese males. The effects of obesity and hypogonadism form a vicious cycle whereby dysregulation of the hypothalamic-pituitary-testicular axis-due to the effect of the release of multiple mediators, thus decreasing GnRH release from the hypothalamus-causes decreases in LH and FSH levels. This leads to lower levels of testosterone, which further increases adiposity because of increased lipogenesis. Cytokines such as TNF-α and interleukins, sirtuins, and other inflammatory mediators like reactive oxygen species are known to affect fertility in obese male adults. There is evidence that parental obesity can be transferred through subsequent generations to offspring through epigenetic marks. Thus, negative expressions like obesity and infertility have been linked to epigenetic marks being altered in previous generations. The interesting aspect is that these epigenetic expressions can be reverted by removing the triggering factors. These positive modifications are also transmitted to subsequent generations.

Red-Fleshed Apple Flavonoids Extract Alleviates Male Reproductive Injury Caused by Busulfan in Mice

In this research, we analyzed the protective effects of red-fleshed apple flavonoid extracts (RAFEs) on male reproductive injury induced by busulfan, using both in vitro and in vivo models. In the cell-based experiments, RAFEs significantly improved cell viability and proliferation rates compared to control groups. Similarly, in vivo testing with male mice showed that RAFEs and whole apple flavonoid extracts (WAFEs) enhanced various biochemical and liver function-related indicators in the testes; however, RAFEs demonstrated superior efficacy in mitigating testicular damage. Through immunohistochemistry, qRT-PCR, and Western blotting, we found that RAFEs notably enhanced the expression of spermatogenesis-related genes. Moreover, RAFEs increased the expression of oxidative stress- and apoptosis-related genes, thereby effectively reducing oxidative damage in the testes. These findings highlight the potential of RAFEs as natural agents for the prevention and treatment of male reproductive injury, paving the way for future research and potential therapeutic applications.

A Longitudinal Study of the Relationship of Adiponectin with Reproduction in Infertile Women Undergoing IVF/ICSI Treatment, and an Experimental Study in Human Granulosa Cells

This study investigated the roles of adiponectin in IVF treatment during Phase I (the basal stage before gonadotropin administration), Phase II (approximately 8 days after gonadotropin administration), and Phase III (on the ovum pick-up day), as well as the effects of adiponectin on CYP19A1 and the FSH receptor (FSHR) mRNA expression in a human granulosa-like tumor cell line (KGN). In human subjects (a longitudinal study, n = 30), blood samples were collected in all phases, while follicular fluid (FF) was only collected in Phase III. The participants were classified into successful and unsuccessful groups based on the determination of fetal heartbeats. KGN cells were treated with adiponectin/FSH/IGF-1 (an experimental study, n = 3). There was no difference in the adiponectin levels between successful and unsuccessful pregnancies in the FF (Phase III) and in serum (all phases), as well as among the three phases in both groups. Serum FSH (Phase I) was positively associated with serum adiponectin in the unsuccessful group, but it had a negative association in the successful group (all phases). Serum adiponectin and serum FSH (Phase I) were positively correlated in the unsuccessful group, whereas they were negatively correlated (all phases) in the successful group. The serum adiponectin levels (Phase III) were significantly higher than in the FF in unsuccessful pregnancies, but there was no difference in successful pregnancies. FF adiponectin concentrations were negatively correlated with serum LH in successful subjects. In KGN cells, adiponectin had no influence on CYP19A1 and FSHR mRNA expression. High adiponectin levels in serum compared to FF (Phase III) in unsuccessful subjects might negatively impact IVF treatment.

Seasonal change of circulating leptin associated with testicular activities of the wild ground squirrels (Citellus dauricus)

The purpose of this study was to explore the variations in the circulating leptin concentrations of the wild ground squirrels in relation to seasonal changes in testicular activities. Hematoxylin-eosin staining showed all types of elongated spermatids and spermatogenic cells existed in the testis in April, while the primary spermatocytes and spermatogonia were most advanced stages of germ cells in June. In addition, the primary spermatocytes, secondary spermatocytes, and spermatogonia were most advanced stages of germ cells in September. The highest circulating leptin concentration was consistent with the maximum body weight results from accumulation of adipose tissue in September. The mRNA expression level of leptin receptor (Ob-R) and STAT3 was lowest in June, raised in September, and remained increased in April. Ob-R and STAT3 were stronger staining in the Leydig cells in July. Moreover, the concentrations of testosterone (T) showed the maximum values in April, the minimum values in June, and significant increases in September. Furthermore, it is worth noting that the levels of T increased with the mRNA levels of Ob-R, STAT3, StAR, and testicular steroidogenic enzymes (3β-HSD, P450c17, and P450scc). Moreover, RNA-seq analyses of testis during the different periods showed that a total of 4209 genes were differentially expressed genes (DEGs); further analysis revealed that DEGs related with the Jak/STAT pathways and reproduction were altered. Taken together, the results suggested that the leptin regulated testicular function through the Jak/STAT pathways and testicular steroidogenic factor expressions.

Seminal Levels of Omentin-1/ITLN1 in Inflammatory Conditions Related to Male Infertility and Localization in Spermatozoa and Tissues of Male Reproductive System

Purpose

Omentin-1/intelectin (ITLN)1 is an adipocytokine with both anti-inflammatory and anti-oxidative stress properties, and little is known about its role in male reproduction. This study was aimed at exploring the relationships among omentin-1/ITLN1, semen parameters and F₂-isoprostanes (F₂-IsoPs), a maker of oxidative stress, in groups of patients affected by different pathologies. In addition, omentin-1/ITLN1 immunolocalization was assessed in ejaculated spermatozoa and in tissues of male reproductive system.

Patients and Methods

Semen samples of infertile patients with varicocele (n = 27), genitourinary infections (n = 17), idiopathic infertility (n = 15) and fertile men (n = 21) were analyzed following WHO guidelines, and seminal plasma were used to determine omentin-1/ITLN1 by ELISA and F₂-IsoP levels by gas chromatography/negative-ion chemical ionization tandem mass spectrometry. Omentin-1/ITLN1 was localized in human sperm and in the tissue of male reproductive system.

Results

Considering all participants, F₂-IsoP and omentin-1/ITLN1 levels were positively correlated (p = 0.000), and both these indices were negatively correlated with sperm parameters. Infertile patients showed lower sperm parameters than fertile ones; varicocele and infection groups had significantly increased levels of F₂-IsoPs (both p = 0.000) and omentin-1/ITLN1 (p = 0.000 and p = 0.001, respectively). Omentin-1/ITLN1 signal was located as a spot in the connecting piece (in 43.5% of cases midpiece was also labeled) of sperm from fertile men and in cytoplasmic residue and in the entire tail in sperm of patients with varicocele and genitourinary infections. A focal omentin-1/ITLN1 immunolabelling was evident in the basal area of epididymal tubule, and a diffuse signal was present in the seminal vesicle epithelium.

Conclusion

Semen omentin-1/ITLN1 originates from seminal vesicles, its levels increase in inflammatory conditions and are negatively correlated with sperm parameters. For this reason, a sort of protective role of omentin-1/ITLN1 can be postulated, as this adipokine shows anti-inflammatory properties also in many other biological systems.

Adipokines in metabolic and reproductive functions in birds: An overview of current knowns and unknowns

Adipose tissue is now recognized as an active endocrine organ, which synthesizes and secretes numerous peptides factors called adipokines. In mammals, they exert pleiotropic effects affecting energy metabolism but also fertility. In mammals, secretion of adipokines is altered in adipose tissue dysfunctions and may participate to obesity-associated disorders. Thus, adipokines are promising candidates both for novel pharmacological treatment strategies and as diagnostic tools. As compared to mammals, birds exhibit several unique physiological features, which make them an interesting model for comparative studies on endocrine control of metabolism and adiposity and reproductive functions. Some adipokines such as leptin and visfatin may have different roles in avian species as compared to mammals. In addition, some of them found in mammals such as CCL2 (chemokine ligand 2), resistin, omentin and FGF21 (Fibroblast Growth factor 21) have not yet been mapped to the chicken genome model and among its annotated gene models. This brief review aims to summarize data (structure, metabolic and reproductive roles and molecular mechanisms involved) related to main avian adipokines (leptin, adiponectin, visfatin, and chemerin) and we will briefly discuss the adipokines that are still lacking in avian species.

Adiposity is associated with anovulation independent of serum free testosterone: A prospective cohort study

BACKGROUND

Obesity, a body mass index (BMI) ≥30 kg/m2 , is linked to infertility, potentially through a greater risk of anovulation due to elevated androgens. Yet, previous studies have not directly assessed the impact of adiposity, or body fat, on anovulation in the absence of clinical infertility.

OBJECTIVE

To characterise the associations between adiposity and anovulation among women menstruating on a regular basis.

METHODS

Women from the EAGeR trial (n = 1200), a randomised controlled trial of low-dose aspirin and pregnancy loss among women trying to conceive, were used to estimate associations between adiposity and incident anovulation. Participants completed baseline questionnaires and anthropometry, and provided blood specimens. Women used fertility monitors for up to six consecutive menstrual cycles, with collection of daily first morning voids for hormone analysis in the first two menstrual cycles for prospective assessment of anovulation. Anovulation was assessed by urine pregnanediol glucuronide or luteinising hormone concentration or the fertility monitor. Weighted mixed-effects log-binomial regression was used to estimate associations between measures of adiposity and incident anovulation, adjusted for free (bioavailable) testosterone, anti-Mullerian hormone (AMH), serum lipids, and demographic and life style factors.

RESULTS

343 (28.3%) women experienced at least one anovulatory cycle. Anovulation risk was higher per kg/m2 greater BMI (relative risk [RR] 1.03, 95% confidence interval (CI) 1.01, 1.04), cm waist circumference (RR 1.01, 95% CI 1.00, 1.02), mm subscapular skinfold (RR 1.02, 95% CI 1.01, 1.03), and mm middle upper arm circumference (RR 1.04, 95% CI 1.01, 1.06) adjusted for serum free testosterone, AMH, lipids, and other factors.

CONCLUSIONS

Adiposity may be associated with anovulation through pathways other than testosterone among regularly menstruating women. This may account in part for reported associations between greater adiposity and infertility among women having menstrual cycles regularly. Understanding the association between adiposity and anovulation might lead to targeted interventions for preventing infertility.

Adiponectin/AdipoRs signaling as a key player in testicular aging and associated metabolic disorders

Aging undergoes serious worsening of peripheral organs and vital physiological processes including reproductive performances. Altered white adipose tissue and adipocyte functioning during aging results in ectopic lipid storage/obesity or metabolic derangements, leading to insulin resistance state. Eventually, accelerating cellular senescence thereby enhancing the high risk of age-associated metabolic alterations. Such alterations may cause derangement of numerous physiologically active obesity hormones, known as "adipokines." Specifically, adiponectin exhibits insulin sensitizing action causing anti-aging and anti-obesity effects via activation of adiponectin receptors (AdipoRs). The male reproductive physiology from reproductive mature stage to advanced senescent stage undergoes insidious detrimental changes. The mechanisms by which testicular functions decline with aging remain largely speculative. Adiponectin has also recently been shown to regulate metabolism and longevity signaling thus prolonging lifespan. Therefore, the strategy for activating adiponectin/AdipoRs signaling pathways are expected to provide a solid basis for the prevention and treatment of aging and obesity-associated reproductive dysfunctions, as well as for ensuring healthy reproductive longevity in humans.

Effect of Irisin on LIF and integrin αvβ3 in rats of implantation failure

OBJECTIVE

The aim of this study is to investigate the effect of irisin on leukemia inhibitory factor (LIF) and integrin αvβ3 in implantation failure uterus.

METHODS

Early pregnant rats were randomly divided into normal group (N), mifepristone treated group (M), irisin group (I) and progestin group (P). The implantation failure model was established using mifepristone. Second, we evaluated the average number of embryos and detected the expression of LIF and integrin αvβ3 protein and mRNA in endometrium.

RESULTS

Compared with group M, the average number of embryos was significantly higher in group N, P and I, the expression of LIF and integrin αvβ3 in endometrium was significantly higher in group N, P and I.

CONCLUSION

Irisin could improve the poor receptive state of endometrium by promoting LIF and integrin αvβ3 secretion to improve blastocyst implantation in rats of implantation failure.

Regulation and function of leptin during ovarian follicular development in cows

Although it is well documented that leptin signals the body nutritional status to the brain, mechanisms of leptin regulation at the ovary are not well understood. This study was conducted to determine whether there was leptin and the receptor for leptin (LEPR) in cattle ovarian follicles and to investigate potential actions of leptin on follicular growth in vivo and on regulation of granulosa cell functions in vitro. There was leptin and LEPR in granulosa and theca cells of dominant and subordinate follicles, with greater immunostaining for leptin in granulosa cells of subordinate follicles. There was a lesser relative abundance of leptin receptor gene-related protein (LEPROT) and of the adiponectin receptors 1 (ADIPOR1) and 2 (ADIPOR2) mRNA transcripts in granulosa cells of subordinate than dominant follicles (P < 0.05). Intrafollicular injection of either 100 or 1000 ng/mL leptin did not affect the diameter and the growth of dominant follicles (P> 0.05). Supplementation of in vitro culture medium with different leptin concentations did not affect (P > 0.05) the relative abundance of hydroxy-delta-5-steroid dehydrogenase, 3 beta- and steroid delta-isomerase 1 (HSD3B1), cytochrome P450 family 11 subfamily A member 1 (CYP11A1), signal transducer and activator of transcription 3 (STAT3) and X-linked inhibitor of apoptosis protein (XIAP) mRNA transcripts in granulosa cells. These findings indicate that leptin and LEPR are present in the follicular cells of cattle ovaries, but leptin apparently does not have essential functions in steroidogenesis and growth of dominant follicles.

Association between levels of aquaporin 3 in the placenta and adiponectin in the umbilical cord blood with gestational diabetes mellitus and pregnancy outcome

Pregnant women with gestational diabetes mellitus (GDM) may have adverse pregnancy outcomes, even if their blood glucose level is well-controlled. Aquaporin 3 (AQP3) and adiponectin (APN) serve important roles in fetal growth and development. However, the associations of AQP3 and APN with GDM and pregnancy outcome are not known. Therefore, the present study was performed to evaluate the expression of AQP3 in the placenta and APN in the umbilical artery blood, and the association of the two factors with GDM and pregnancy outcome. The patient cohort was divided into two groups: Pregnant women with GDM; and pregnant women with normal glucose tolerance (NGT). The expression levels of AQP3 in the placenta and APN in the umbilical artery blood were detected. Logistic regression was used to analyze the associations of AQP3 and APN with GDM and pregnancy outcome. The expression levels of AQP3 and AQP3 mRNA in the placenta of the GDM group were decreased compared with that of the NGT group, and the difference was statistically significant (P<0.05). The expression of APN in the umbilical artery blood of the GDM group was also decreased compared with that of the NGT group, and the difference was also statistically significant (P<0.05). Multivariate logistic regression analyses indicated that the AQP3 and APN levels were negatively correlated not only with the risk of developing GDM [AQP3 odds ratio (OR)=5.00 (P<0.01); APN OR=2.98 (P=0.01)], but also with abnormal pregnancy outcome [(AQP3 OR=4.64 (P<0.01); APN OR=5.41 (P<0.01)]. The levels of AQP3 in the placenta and APN in the umbilical cord blood were associated with GDM, and the risk of GDM was increased in pregnant women with decreased AQP3 and APN levels. The AQP3 and APN levels also had an effect on pregnancy outcome. The risk of abnormal pregnancy outcomes, including cesarean section, macrosomia, fetal distress and neonatal asphyxia, was increased in pregnant women with decreased AQP3 and APN levels.

The gonadal expression pattern of lipocalin‑2 and 24p3 receptor is modified in the gonads of the offspring of obese rats

Obesity represents a global health and economic burden, affecting millions of individuals worldwide. This pathology is associated with a chronic low-grade inflammatory state that is partially responsible for the development of other cardiometabolic complications. Clinical studies have reported an association between high circulating levels of lipocalin-2 (Lcn2) and increased body weight. Additionally, there is scientific evidence demonstrating the impact of maternal obesity on fetal programming. The latter and the fact that the authors previously found that Lcn2 and its receptor (24p3R) are expressed in the gonads of wild-type rats, led to the analysis of their mRNA profile and cellular localization in gonads collected from the offspring of obese rats at 21 days postconception (dpc), and 0, 2, 4, 6, 12, 20 and 30 days postnatal (dpn) in the present study. Semi-quantitative PCR revealed a statistically significant downregulation of Lcn2 and 24p3R mRNA at 21 dpc in the ovaries (P<0.01) and testicles (P<0.001) of the offspring of obese mothers. At 30 dpn, the relative expression of Lcn2 mRNA decreased significantly in the ovaries of the experimental group (P<0.05), while Lcn2 mRNA expression was not detectable in testicles. Regarding 24p3R, its mRNA was only significantly decreased at 21 dpc in ovaries of pups of obese mothers. At 30 dpn, the change in females was not significant. Conversely, in testicles, 24p3R mRNA levels increased slightly in the experimental group at 30 dpn. The Lcn2 protein signal was less intense in gonadal tissue sections from 30 dpn offspring of obese rats (P<0.001), whereas the 24p3R signal was downregulated in ovaries (P<0.001) and slightly upregulated in testicles. It was concluded that maternal obesity changes the expression of Lcn2 and 24p3R in the gonads of the offspring of obese rats, possibly through fetal programming. The consequences of this dysregulation for the offspring's gonadal function remains to be determined.

The effect of excess body fat on female and male reproduction

The dramatic increase in the prevalence of obesity coincides with a decline in reproductive health indices in both sexes. Energy excess mediates changes to the regulatory mechanisms of the reproductive system. Obese individuals exhibit increased estrogen concentrations, due to the overexpression of aromatase in the adipose tissue; via a negative feedback loop, men present with symptoms of hypogonadotropic hypogonadism. These hormonal changes, along with increased oxidative stress, lipotoxicity and disturbances in the concentrations of adipokines, directly affect the gonads, peripheral reproductive organs and the embryo. Clinical evidence is somewhat contradicting, with only some studies advocating worse semen parameters, increased incidence of erectile dysfunction, increased doses of ovulation induction medications, and worse live birth rates in assisted reproductive technology (ART) cycles in obese individuals compared with those of normal weight. Similar conclusions are drawn about patients with insulin resistance syndromes, namely polycystic ovary syndrome (PCOS). As far as treatment options are concerned, lifestyle changes, medical therapy and bariatric surgery may improve the reproductive outcome, although the evidence remains inconclusive. In this review, we summarize the evidence on the association of obesity and reproductive health on both the molecular and the clinical level, and the effect of weight-loss interventions on reproductive potential.

Interstitial Leydig Cell Tumorigenesis-Leptin and Adiponectin Signaling in Relation to Aromatase Expression in the Human Testis

Although epidemiological studies from the last years report an increase in the incidences of Leydig cell tumors (previously thought to be a rare disease), the biochemical characteristics of that tumor important for understanding its etiology, diagnosis, and therapy still remains not completely characterized. Our prior studies reported G-protein coupled estrogen receptor signaling and estrogen level disturbances in Leydig cell tumors. In addition, we found that expressions of multi-level-acting lipid balance- and steroidogenesis–controlling proteins including peroxisome proliferator-activated receptor are altered in this tumor. In order to get deeper into the other molecular mechanisms that regulate lipid homeostasis in the Leydig cell tumor, here we investigate the presence and expression of newly-described hormones responsible for lipid homeostasis balancing (leptin and adiponectin), together with expression of estrogen synthase (aromatase). Samples of Leydig cell tumors (n = 20) were obtained from patients (31–45 years old) and used for light and transmission electron microscopic, western blotting, and immunohistochemical analyses. In addition, body mass index (BMI) was calculated. In tumor mass, abundant lipid accumulation in Leydig cells and various alterations of Leydig cell shape, as well as the presence of adipocyte-like cells, were observed. Marked lipid content and various lipid droplet size, especially in obese patients, may indicate alterations in lipid homeostasis, lipid processing, and steroidogenic organelle function in response to interstitial tissue pathological changes. We revealed significantly increased expression of leptin, adiponectin and their receptors, as well as aromatase in Leydig cell tumors in comparison to control. The majority of patients (n = 13) were overweight as indicated by their BMI. Moreover, a significant increase in expression of phospholipase C (PLC), and kinases Raf, ERK which are part of adipokine transductional pathways, was demonstrated. These data expand our previous findings suggesting that in human Leydig cell tumors, estrogen level and signaling, together with lipid status, are related to each other. Increased BMI may contribute to certain biochemical characteristics and function of the Leydig cell in infertile patients with a tumor. In addition, altered adipokine-estrogen microenvironment can have an effect on proliferation, growth, and metastasis of tumor cells. We report here various targets (receptors, enzymes, hormones) controlling lipid balance and estrogen action in Leydig cell tumors indicating their possible usefulness for diagnostics and therapy.

Follicular fluid leptin as a marker for pregnancy outcomes in women undergoing IVF treatment: a systematic review and meta-analysis

Leptin is a hormone secreted mainly by the adipocytes with an essential role in the regulation of body weight. It acts on the reproductive axis at different sites, with stimulatory effects at the hypothalamus and pituitary and inhibitory interactions at the gonads. To investigate the influence of leptin on pregnancy outcomes in women undergoing IVF, we undertook a systematic review. A search of PubMed from 1966 to 2018 identified ten studies meeting the inclusion criteria. Outcomes were BMI, serum leptin level at hCG injection, serum and follicular fluid leptin level at the oocyte pick up, and serum 17β-oestradiol level at oocyte pick up time, oocytes retrieved and embryo transfer number. Results indicated that follicular fluid leptin concentrations at the oocyte pick up were significantly lower in women who became pregnant compared to those who did not (MD = -4.53 (ng/ml); 95% CI: -7.78, -1.78; p value < 0.006). In conclusion, elevated leptin concentrations in follicular fluid at oocyte pick up time is significantly associated with an adverse pregnancy outcome in women undergoing an IVF programme.

Familial Partial Lipodystrophy (FPLD): Recent Insights

Lipodystrophies are a heterogeneous group of congenital or acquired disorders, characterized by partial or generalized loss of adipose tissue. Familial partial lipodystrophy (FPLD) presents with genetic and phenotypic variability with insulin resistance, hypertriglyceridemia and hepatic steatosis being the cardinal metabolic features. The severity of the metabolic derangements is in proportion with the degree of lipoatrophy. The underpinning pathogenetic mechanism is the limited capacity of adipose tissue to store lipids leading to lipotoxicity, low-grade inflammation, altered adipokine secretion and ectopic fat tissue accumulation. Advances in molecular genetics have led to the discovery of new genes and improved our knowledge of the regulation of adipose tissue biology. Diagnosis relies predominantly on clinical findings, such as abnormal fat tissue topography and signs of insulin resistance and is confirmed by genetic analysis. In addition to anthropometry and conventional imaging, new techniques such as color-coded imaging of fat depots allow more accurate assessment of the regional fat distribution and differentiation of lipodystrophic syndromes from common metabolic syndrome phenotype. The treatment of patients with lipodystrophy has proven to be challenging. The use of a human leptin analogue, metreleptin, has recently been approved in the management of FPLD with evidence suggesting improved metabolic profile, satiety, reproductive function and self-perception. Preliminary data on the use of glucagon-like peptide 1 receptor agonists (GLP1 Ras) and sodium-glucose co-transporter 2 (SGLT2) inhibitors in cases of FPLD have shown promising results with reduction in total insulin requirements and improvement in glycemic control. Finally, investigational trials for new therapeutic agents in the management of FPLD are underway.

Body fat distribution influences ART outcomes

Body mass index (BMI) is the widely used method to evaluate obesity, but it cannot differentiate lean from fat mass neither mass distribution. Other methods have been proposed for this evaluation, as waist and hip circumferences (WC, HC) and ratio (WHR) and body fat analysis by bioimpedance (BF%), but they have not been applied to evaluate assisted reproduction (ART) outcomes. The present study aims at determining whether body composition and adipose tissue distribution are better than BMI on ART outcomes. Analysis was performed through five anthropometric measurements of 788 women submitted to controlled ovarian hyperstimulation and in vitro fertilization techniques. The increase of body fat, independently of the measurement method, was associated to worse reproductive results. However, a surprising finding was that eutrophic women with WC lower than 80 cm showed gestation rates two times superior (38.9% versus 14.3%) when compared to eutrophic women with WC larger than 80 cm (p = .002). Furthermore, obese women with WHR higher than 0.85 showed worse ART results, considering oocytes retrieved, mature oocytes and fertilization when compared to those with WHR lower than 0.85. As a conclusion, it was observed that the body fat distribution, especially WC, was more relevant than BMI to predict ART outcomes.

Comparison of Adiponectin Levels During the Menstrual Cycle Between Normal Weight and Overweight/Obese Young Females

To compare serum adiponectin changes across the menstrual cycle between normal weight and overweight/obese young women and its correlation with serum estradiol. Young women (n=56) with regular menstrual cycle had been grouped according to their BMI into normal weight group (n=26) and overweight /obese group (n=30). Blood samples were drawn during early follicular (FP), pre-ovulatory (OP) and luteal phases (LP) of menstrual cycle for serum adiponectin and estradiol levels determination using enzyme-linked immunosorbent assay. Adiponectin serum level showed a significant decreasing pattern across the phases of menstrual cycle in normal weight group. This pattern was absent in the overweight/obese group. In addition, serum adiponectin was lower in overweight/obese group compared to normal weight subjects through all phases of menstrual cycle. No correlation was found between adiponectin and estradiol levels in both groups. A significant variation of serum adiponectin level was detected across the menstrual cycle in females with normal weight. In comparison, overweight/obese group showed a relatively stable adiponectin level throughout the cycle. This lack of adiponectin variation might be added to the complex mechanisms lies behind obesity-related female infertility.

Involvement of Novel Adipokines, Chemerin, Visfatin, Resistin and Apelin in Reproductive Functions in Normal and Pathological Conditions in Humans and Animal Models

It is well known that adipokines are endocrine factors that are mainly secreted by white adipose tissue. Their central role in energy metabolism is currently accepted. More recently, their involvement in fertility regulation and the development of some reproductive disorders has been suggested. Data concerning the role of leptin and adiponectin, the two most studied adipokines, in the control of the reproductive axis are consistent. In recent years, interest has grown about some novel adipokines, chemerin, visfatin, resistin and apelin, which have been found to be strongly associated with obesity and insulin-resistance. Here, we will review their expression and role in male and female reproduction in humans and animal models. According to accumulating evidence, they could regulate the secretion of GnRH (Gonadotropin-Releasing Hormone), gonadotropins and steroids. Furthermore, their expression and that of their receptors (if known), has been demonstrated in the human and animal hypothalamo-pituitary-gonadal axis. Like leptin and adiponectin, these novel adipokines could thus represent metabolic sensors that are able to regulate reproductive functions according to energy balance changes. Therefore, after investigating their role in normal fertility, we will also discuss their possible involvement in some reproductive troubles known to be associated with features of metabolic syndrome, such as polycystic ovary syndrome, gestational diabetes mellitus, preeclampsia and intra-uterine growth retardation in women, and sperm abnormalities and testicular pathologies in men.

Apelin system detection in the reproductive apparatus of ewes grazing on semi-natural pasture

Apelin (APLN) is an adipokine with pleiotropic effects involved in the regulation of metabolic, cardiovascular, immune, and electrolyte balance function. Recent studies demonstrated a pivotal role in the regulation of male and female reproduction. APLN and its receptor (APLNR) were found in the hypothalamic-pituitary-gonad axis tissues, regulating gonadotropin release and steroidogenesis. However, to date, there are no studies that describe APLN system in the reproductive apparatus of the sheep. The study was performed on 10 Comisana x Appenninica adult dry ewes reared in a semi-natural pasture. Organ samples were collected from five animals in the two pasture functional phases: after maximum pasture flowering (Group 1) and after maximum pasture dryness (Group 2). Experiments were devised to characterize the gene expression and protein localization of the APLN/APLNR system in ewe reproductive apparatus; in addition, the concentration of plasma APLN was evaluated during the trial. Through immunohistochemical analysis, a positive staining for APLN was observed in the large luteal cells, in the epithelial cell coat of the ampulla, in the uterus epithelial lining and in the uterine glands. APLNR was observed in the granulosa cells, in the large luteal cells, in the secreting cells of the ampulla, in the uterus epithelial lining and uterine glands. The transcripts for APLN and APLNR were evidenced in all organ tissues examined. The highest level of APLN mRNA was detected in the Group 2 ewes in the luteal phase of the ovarian cycle compared to Group 1 ewes in the anestrous one. The relative content of APLN transcript was respectively twofold higher in the ovary (P < 0.05) and uterus (P < 0.05) and threefold higher in the ampulla (P < 0.05) in the Group 2 vs Group 1. The same trend of APLN transcript was evaluated for APLNR mRNA in uterus (P < 0.05) and ovary (P < 0.05). No difference was evidenced between Group 1 and Group 2 for APLNR mRNA levels. The plasma APLN level was fairly constant during the trial period. In conclusion, the present data suggest that the apelinergic system is involved in the reproduction function of ewes, being differentially distributed and expressed in the organs of the reproductive apparatus of ewes; these variations could be related to the sexual cycle and to the cyclic activity of the reproductive apparatus.

Leptin gene polymorphism (rs7799039; G2548A) is associated with changes in serum lipid concentrations during pregnancy: a prospective cohort study

PURPOSE

Little is known about the effects of leptin and leptin receptor polymorphisms on lipid changes during pregnancy. The aims of this study were to evaluate the associations between the single nucleotide polymorphisms (SNPs) of leptin and leptin receptor genes and the lipid concentrations during pregnancy; and to test whether dietary intake is a mediator in these associations.

METHODS

A prospective cohort of 154 pregnant women was followed up in Rio de Janeiro, Brazil during the following gestational periods: 5-13th, 20-26th and 30-36th weeks. HDL-C, total cholesterol (TC) and triglyceride (TG) were measured by the enzymatic colorimetric method, and LDL-C was calculated. DNA was extracted by the phenol-chloroform method, and leptin (G2548A, rs7799039) and leptin receptor SNPs (Q223R; rs1137101 and K109R; rs1137100) were genotyped using real-time PCR. Statistical analyses included linear mixed-effect models.

RESULTS

Women with the AA genotype of G2548A polymorphism reported a higher fat and total energy intake and had a higher increase in TG concentration during pregnancy than women with AG or GG genotype. The association between G2548A SNP and TG concentrations was not attenuated by adjusting for total lipid (g) and energy (kcal) intake. We did not observe significant associations between the Q223R and K109R SNPs and the lipid concentrations.

CONCLUSIONS

Women homozygous for the A allele of the leptin SNP (G2548A) had a higher increase in TG concentrations per gestational week compared with women with the AG or GG genotype. This is an exploratory and hypothesis-generating study, and the results need confirmation in studies with larger sample sizes.'

Adipocytokines may delay pubertal maturation of human Sertoli cells

Reproduction is an important target of obesity complications, including adverse effects on spermatogenesis and steroidogenesis. Adipocytokines are key mediators in various complications of obesity. Our aim was to study the potential of adipocytokines to affect Sertoli cell function, which is crucial for spermatogenesis, and possibly link these findings to the observed attenuation of spermatogenesis in obese males. Testicular biopsies were obtained from healthy donors. Highly purified adult human Sertoli cells (HSCs) were isolated by fluorescence-activated cell sorting. Cells were cultured and exposed to different concentrations of adipocytokines (10-1000ngmL-1 ) for 2-7 days. Expression of selected Sertoli cell genes was quantified by quantitative polymerase chain reaction. Long-term treatment (7 days) of HSCs with higher concentrations of chemerin, irisin, nicotinamide phosphoribosyltransferase (Nampt), resistin and progranulin significantly suppressed FSH receptor expression (by 79%, 83%, 64%, 71% and 26% respectively; P P invitro , may negatively affect Sertoli cell maturation and retain these cells in a more prepubertal stage. This could negatively affect testis function and add to fertility problems in obese adults.

Serum chemerin levels are negatively associated with male fertility and reproductive hormones

STUDY QUESTION

Are chemerin levels different in subfertile men compared to men from the general population, and how does chemerin relate to reproductive hormonal status?

SUMMARY ANSWER

Chemerin is negatively associated to LH, SHBG and estradiol and lower levels of chemerin are detected among subfertile men compared to controls.

WHAT IS KNOWN ALREADY

Adipokines have pleiotropic effects on tissue homeostasis and have been shown to affect both sex steroid production and action. Among adipokines the newly characterized chemokine chemerin is suggested to influence testosterone production in males, but whether serum levels associate with testosterone or male subfertility has not yet been reported.

STUDY DESIGN, SIZE, DURATION

Case control study comprising a consecutive group of men from infertile couples referred to Reproductive Medicine Centre at Skane University Hospital from 2006 through 2012, and age-matched controls. Participants were enrolled in years 2011-2013.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Males from infertile couples (n = 180) aged 18-50 years with sperm concentration <20 × 106/ml and age-matched controls (n = 139) from the general population were enrolled. Serum concentrations of total testosterone (TT), calculated free testosterone (cFT), luteinizing hormone (LH), follicle-stimulating hormone (FSH), estradiol (E2) and sex-hormone binding globuline (SHBG) as well as the adipokines chemerin, adiponectin and leptin were measured. Anthropometrics and biochemical parameters of glucose and lipid metabolism were assessed.

MAIN RESULTS AND THE ROLE OF CHANCE

Chemerin levels were lower in subfertile men compared to controls (mean diff. 7.1 ng/ml; 95% CI, 3.7; 11 ng/ml; P < 0.001) even after adjustment for BMI. After adjustment for age, BMI, smoking, leptin and adiponectin, chemerin associated negatively with LH (ß = -4.2; P = 0.02), E2 (ß = -10; P = 0.004) and SHBG (ß = -7.4, P = 0.003). Men with elevated LH levels had lower chemerin levels compared to those with LH levels within the normal range (mean diff. 4.8 ng/ml; 95% CI, 0.16; 9.4 ng/ml; P = 0.04).

LIMITATIONS, REASONS FOR CAUTION

Single sample blood test with immunoassays for determination of hormone levels. Heterogeneous group of subfertile subjects.

WIDER IMPLICATIONS OF THE FINDINGS

Even though chemerin has been positively associated with BMI, inverse association with subfertility suggests that it is independently linked to reproductive function, a hypothesis that warrants further assessment.

STUDY FUNDING/COMPETING INTEREST(S)

This work was supported by grants from EU Interreg V (ReproUnion) program as well as Swedish Governmental Fund for Clinical Research. The authors have no conflicts of interest.

Deletion of leptin receptors in vagal afferent neurons disrupts estrogen signaling, body weight, food intake and hormonal controls of feeding in female mice

Deletion of the leptin receptor from vagal afferent neurons (VAN) using a conditional deletion (Nav1.8/LepR^fl/fl) results in an obese phenotype with increased food intake and lack of exogenous cholecystokinin (CCK)-induced satiation in male mice. Female mice are partially protected from weight gain and increased food intake in response to ingestion of high-fat (HF) diets. However, whether the lack of leptin signaling in VAN leads to an obese phenotype or disruption of hypothalamic-pituitary-gonadal axis function in female mice is unclear. Here, we tested the hypothesis that leptin signaling in VAN is essential to maintain estrogen signaling and control of food intake, energy expenditure, and adiposity in female mice. Female Nav1.8/LepR^fl/fl mice gained more weight, had increased gonadal fat mass, increased meal number in the dark phase, and increased total food intake compared with wild-type controls. Resting energy expenditure was unaffected. The decrease in food intake produced by intraperitoneal injection of CCK (3 μg/kg body wt) was attenuated in female Nav1.8/LepR^fl/fl mice compared with wild-type controls. Intraperitoneal injection of ghrelin (100 μg/kg body wt) increased food intake in Nav1.8/LepR^fl/fl mice but not in wild-type controls. Ovarian steroidogenesis was suppressed, resulting in decreased plasma estradiol, which was accompanied by decreased expression of estrogen receptor-1 (Esr1) in VAN but not in the hypothalamic arcuate nucleus. These data suggest that the absence of leptin signaling in VAN is accompanied by disruption of estrogen signaling in female mice, leading to an obese phenotype possibly via altered control of feeding behavior.

Mechanisms of Adiponectin Action in Fertility: An Overview from Gametogenesis to Gestation in Humans and Animal Models in Normal and Pathological Conditions

Adiponectin is the most abundant plasma adipokine. It mainly derives from white adipose tissue and plays a key role in the control of energy metabolism thanks to its insulin-sensitising, anti-inflammatory, and antiatherogenic properties. In vitro and in vivo evidence shows that adiponectin could also be one of the hormones controlling the interaction between energy balance and fertility in several species, including humans. Indeed, its two receptors—AdipoR1 and AdipoR2—are expressed in hypothalamic–pituitary–gonadal axis and their activation regulates Kiss, GnRH and gonadotropin expression and/or secretion. In male gonads, adiponectin modulates several functions of both somatic and germ cells, such as steroidogenesis, proliferation, apoptosis, and oxidative stress. In females, it controls steroidogenesis of ovarian granulosa and theca cells, oocyte maturation, and embryo development. Adiponectin receptors were also found in placental and endometrial cells, suggesting that this adipokine might play a crucial role in embryo implantation, trophoblast invasion and foetal growth. The aim of this review is to characterise adiponectin expression and its mechanism of action in male and female reproductive tract. Further, since features of metabolic syndrome are associated with some reproductive diseases, such as polycystic ovary syndrome, gestational diabetes mellitus, preeclampsia, endometriosis, foetal growth restriction and ovarian and endometrial cancers, evidence regarding the emerging role of adiponectin in these disorders is also discussed.

Leptin Receptor as a Potential Target to Inhibit Human Testicular Seminoma Growth

Although in past decades the adipokine leptin and its own receptor have been considered as significant cancer biomarkers, their potential involvement in human testicular seminoma growth and progression remains unexplored. Here, we showed that the expression of leptin and its receptor was significantly higher in human testicular seminoma compared with normal adult testis. Human seminoma cell line TCam-2 also expressed leptin along with the long and short isoforms of leptin receptor, and in response to leptin treatment showed enhanced activation of its downstream effectors. In line with these results, leptin stimulation significantly increased the proliferation and migration of TCam-2 cells. Treatment of TCam-2 cells with the peptide Leu-Asp-Phe-Ile (LDFI), a full leptin-receptor antagonist, completely reversed the leptin-mediated effects on cell growth and motility as well as reduced the expression of several leptin-induced target genes. More importantly, the in vivo xenograft experiments showed that LDFI treatment markedly decreased seminoma tumor growth. Interestingly, LDFI-treated tumors showed reduced levels of the proliferation marker Ki-67 as well as decreased expression of leptin-regulated genes. Taken together, these data identify, for the first time, leptin as a key factor able to affect testicular seminoma behavior, highlighting leptin receptor as a potential target for novel potential treatments in this type of cancer.

Modulation of the transcriptomic profile of the R2C tumor Leydig cell line by the adipose tissue derived hormone leptin

Leptin is an important adipose derived hormone being secreted by adipocytes and involved in appetite regulation. Disruption of normal plasma levels of leptin has been associated with the pathogenesis of obesity. It is now well established that obesity is associated to an increased risk of cancer development, including testicular cancers. Recently, we have shown that high levels of leptin have inhibitory effects on cAMP-dependent steroidogenic genes expression in MA-10 Leydig cells. Hence, we examined if leptin could alter the transcriptome of the constitutively steroidogenic rat tumor Leydig cell line R2C. These cells were treated with high levels of leptin (1000 ng/ml) for 4 h, followed by mRNA extraction and RNA-Seq analysis. Interestingly, leptin had no effect on steroidogenic gene expression or pathways promoting tumorigenesis of this cell line. Genes being upregulated or downregulated by leptin were enriched in biological processes that were non-relevant to Leydig cell function. Surprisingly, lepr isoforms were weakly expressed in R2C cells and may explain in part the low levels of leptin's response for tumor Leydig cells. Hence, the current findings suggest that acute treatments of tumor Leydig cells with high levels of leptin have negligible effects on transcriptomics and rather supports that leptin would have a central effect on the hypothalamus to influence testicular function.

Ctrp9 and adiponectin receptors in Nile tilapia (Oreochromis niloticus): Molecular cloning, tissue distribution and effects on reproductive genes

As the close paralog of adiponectin, C1q/TNF-Related Protein 9 (CTRP9) has been reported to be involved in the regulation of glucose and fat metabolism, immunization and endothelial cell functions. However, information regarding the actions of Ctrp9 on reproduction is extremely limited in fish. As a first step, Ctrp9, adiponectin receptor 1 (Adipor1) and Adipor2 were identified from Nile tilapia. The open reading frame (ORF) of ctrp9 was 1020 bp which encoded a 339 amino acids. Moreover, the ORFs of adipor1 and adipor2 were 1131 bp and 1134 bp encoding 376 and 377 amino acids, respectively. Tissue distribution showed that ctrp9 mRNA levels were highest in the kidney in both sexes. And, the expression of adipor1 and adipor2 were widely distributed in all tissues examined, exhibiting high levels in the brain, gonad, gut and stomach. In addition, intraperitoneal (i.p.) injection of gCtrp9 (globular Ctrp9) suppressed the hypothalamic expression of gnrh2 (gonadotropin-releasing hormone 2) and gnrh3, as well as gthα (gonadotropic hormone α), fshβ (follicle-stimulating hormone β), lhβ (luteinizing hormone β), lhr (LH receptor) and fshr (FSH receptor) mRNA levels in the pituitary. The mRNA levels of adipor1, but not adipor2, in the gonads were also inhibited after injection. Moreover, the levels of serum E2 (estrogen) in female and T (testosterone) in male were significantly decreased after injection of gCtrp9. Overall, our data provides novel data indicating, for the first time, a regulatory effect of CTRP9 on teleost reproduction.

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.

Adipokines in Semen: Physiopathology and Effects on Spermatozoas

Adipokines are secreted by adipose tissue and could be the link between obesity and infertility. Different studies investigated the involvement of adipokines in reproductive functions but only a few have looked into the male part. This review assesses adipokine functions on male reproductive parameters. Adiponectin seems to have a positive effect on sperm parameters, whereas other adipokines such as resistin or chemerin would have a rather deleterious effect on spermatogenesis. Semen parameters seem to be impacted when resistin and chemerin are increased: indeed, there is a decrease of sperm motility. Sperm morphology is improved when adiponectin is increased. The most studied adipokine, leptin, has a dual effect with a positive effect on sperm at physiological levels and a negative one for high seminal concentrations. Many semen parameters and fertility itself are disturbed according to semen adipokine levels, even if it is not the only interfering element. Taken together, adipokines are found in human and animal semen and most of them or their receptors are expressed in male genital tract. Although the pathophysiological role of adipokines in semen is not clearly elucidated, the adipokines could influence sperm functionality and could be potential biomarkers of male fertility.

Role of leptin and the leptin receptor in the pathogenesis of varicocele-induced testicular dysfunction

The present study investigated the expression of leptin and its receptor in the left testis and hypothalamus of rats with varicocele and clarified their roles in the pathogenesis of varicocele-induced testicular dysfunction. A total of 40 male rats were divided randomly into four groups. Groups 1 (G1) and 3 (G3) underwent a sham operation. Groups 2 (G2) and 4 (G4) underwent operations to form a varicocele created by partial ligation of the left renal vein. G1 and G2 rats were euthanized 4 weeks after the operation while G3 and G4 rats were euthanized at 8 weeks. The expression of leptin and its receptor was analyzed by immunohistochemistry. The mRNA levels of leptin, its receptor, kisspeptin (KiSS-1), G-protein coupled receptor 54 (GPR54), gonadotropin releasing hormone (GnRH), luteinizing hormone (LH), and follicle-stimulating hormone (FSH) were measured by reverse transcription-quantitative polymerase chain reaction. Testicular spermatogenesis function and gonadal hormone levels were measured. Compared with G1 and G3, the expression of leptin and its receptor in rat testis was significantly higher in G2 and G4, respectively. Leptin expression was inversely associated with the number of sperm in the left epididymis, thickness of the seminiferous epithelium and the diameter of seminiferous tubules. The expression of leptin receptors in the hypothalamus of G2 and G4 was significantly increased compared with that in G1 and G3, respectively. The mRNA levels of KiSS-1, GPR54, GnRH, LH and FSH in G2 and G4 were significantly increased compared with that in G1 and G3, respectively. Serum testosterone levels in G2 and G4 rats were significantly lower than those in G1 and G3 rats, respectively. There was no significant difference between the serum levels of FSH, LH and leptin. These results suggest that leptin and its receptor may serve significant roles in the pathogenesis of varicocele-induced testicular dysfunction.

Association of adiponectin gene variants with idiopathic recurrent miscarriage according to obesity status: a case-control study

BACKGROUND

This study addresses whether the association of adiponectin gene (ADIPOQ) variants with idiopathic recurrent pregnancy loss (RPL) is influenced by obesity.

METHODS

Retrospective case-control study performed in outpatient obstetrics/gynecology clinics. Study subjects comprised 308 women with RPL, defined as ≥ 3 consecutive miscarriages of unknown etiology, and 310 control women. ADIPOQ genotyping was done by allele exclusion method on real-time PCR.

RESULTS

Of the 14 ADIPOQ variants tested, the minor allele frequency (MAF) of rs4632532, rs17300539, rs266729, rs182052, rs16861209, and rs7649121 were significantly higher, while rs2241767, and rs1063539 MAF were lower in RPL cases, hence assigning RPL-susceptibility and protection to these variants, respectively. Higher frequencies of heterozygous rs17300539 and rs16861209, and homozygous rs4632532, rs266729, and rs182052 genotypes, and reduced frequencies of heterozygous rs1063539 and rs2241767, homozygous rs2241766 genotypes were seen in RPL cases. ADIPOQ rs4632532, and rs2241766 were associated with RPL in obese, while rs1063539 and rs16861209 were associated with RPL in non-obese women; rs182052 and rs7649121 associated with RPL independently of BMI changes. Based on LD pattern, two haplotype blocks were identified. Within Block 1 containing rs4632532, rs16861194, rs17300539, rs266729, rs182052, rs16861209, rs822396, and rs7649121, increased frequency of CAGGACAT and TAACGAAA, and reduced frequency of TAGCGCAA haplotypes were seen in RPL cases when compared to controls, thereby assigning RPL susceptibility and protection, respectively.

CONCLUSION

This is the first study to document contribution of ADIPOQ variants and haplotypes with RPL, and also to underscore the contribution of obesity to genetic association studies.

Influence of serum HMW adiponectin level in patients with pregnancy-induced hypertension syndrome on the occurrence of eclampsia in secondary pregnancy

In the present study, we studied the influence of serum high-molecular weight adiponectin (HMWA) levels in patients with pregnancy-induced hypertension (PIH) on the occurrence of eclampsia in secondary pregnancy and its related mechanisms. In total, 130 patients who were diagnosed with PIH for the first time were selected for this study; the median interval of the secondary pregnancy was 28.5 months. The serum HMWA and leptin levels both times were detected, and the insulin resistance indexes (HOMA-IR) were calculated. The serum inflammatory indexes in the secondary pregnancy included interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α) levels, and the oxidative stress indexes included methane dicarboxylic aldehyde (MDA) and oxidized low-density lipoprotein (ox-LDL) levels. The expression levels of adiponectin receptor 2 and cyclooxygenase-2 (COX-2) in placental tissue were detected. In secondary pregnancy, there were a total of 20 cases of eclampsia (15.38%), including 2 cases of mild PIH, 8 cases of moderate PIH and 10 cases of severe PIH; differences were statistically significant when compared to patients without eclampsia (p<0.001). The serum HMWA levels in patients with severe PIH in the first pregnancy were significantly lower than those in patients with mild and moderate PIH, and the serum levels in patients with mild PIH were the highest. The leptin levels in patients with severe PIH were significantly higher than those in patients with mild and moderate PIH, and the leptin levels in patients with mild PIH were the lowest (p<0.05). The HMWA levels in patients with eclampsia in the secondary pregnancy was significantly lower than those in patients without eclampsia, and the leptin levels in patients with eclampsia were significantly increased. The HMWA levels in patients with eclampsia in the secondary pregnancy were lower than that in the first pregnancy, whereas the leptin levels were higher than that in the first pregnancy (p<0.05). HOMA-IR, IL-6, TNF-α, MDA and ox-LDL levels in patients with eclampsia were significantly higher than those in patients without eclampsia (p<0.05), and the adiponectin receptor 2 and COX-2 expression levels in the placental tissue were significantly higher than those in patients without eclampsia (p<0.05). Therefore, the serum HMWA levels are closely related to the occurrence of eclampsia in PIH patients in secondary pregnancy, and it influences insulin resistance, inflammatory response and oxidative stress response, which is correlated with increased adiponectin receptor 2 and COX-2 protein expression in placental tissue. Consequently, HMWA may be an important target for the intervention of preventing eclampsia for PIH patients in secondary pregnancy.

Can serum vaspin levels predict clomiphene resistance in infertile women with PCOS?

OBJECTIVE

To determine whether serum vaspin levels can predict the success of ovulation induction and clomiphene resistance in anovulatory women with PCOS.

STUDY DESIGN

We designed a prospective case control study. The study population (n=49) was composed of infertile women with PCOS who underwent ovulation induction with clomiphene citrate. Patients were divided into two groups based on their treatment response. Group I consisted of patients with failed ovulation induction, and group II consisted of patients with successful ovulation induction. The study group characteristics, including age, BMI, waist-to-hip ratio, parity, hormone profiles, fasting insulin and glucose levels, HOMA-IR, triglycerides, and cholesterol and serum vaspin levels, were compared between the study groups.

RESULT(S)

There were 29 patients in Group I with failed ovulation induction (59.2%), and Group II consisted of 20 patients with successful ovulation induction (40.8%). No differences in characteristics were found. However, serum vaspin levels were significantly lower in responders achieving ovulation (p=0.001; p<0.01). At a vaspin level of 3.74, the sensitivity, specificity, positive predictive and negative predictive values were 90%, 72.4%, 69.2% and 91.3%, respectively. The odds ratio was determined to be 14.87 (95% CI: 3.41-64.88) as the cut-off point. No significant correlation was found in serum vaspin measurements between pregnant and non-pregnant patients who had achieved successful ovulation induction (p=0.5).

CONCLUSION(S)

Serum vaspin level may be a useful marker for the prediction of ovulation induction success in treatment with clomiphene citrate, and increased vaspin levels (≥3.74ng/mL) are correlated with clomiphene resistance in patients with PCOS according to our study results.

Adiponectin protects against development of metabolic disturbances in a PCOS mouse model

Adiponectin, together with adipocyte size, is the strongest factor associated with insulin resistance in women with polycystic ovary syndrome (PCOS). This study investigates the causal relationship between adiponectin levels and metabolic and reproductive functions in PCOS. Prepubertal mice overexpressing adiponectin from adipose tissue (APNtg), adiponectin knockouts (APNko), and their wild-type (WT) littermate mice were continuously exposed to placebo or dihydrotestosterone (DHT) to induce PCOS-like traits. As expected, DHT exposure led to reproductive dysfunction, as judged by continuous anestrus, smaller ovaries with a decreased number of corpus luteum, and an increased number of cystic/atretic follicles. A two-way between-groups analysis showed that there was a significant main effect for DHT exposure, but not for genotype, indicating adiponectin does not influence follicle development. Adiponectin had, however, some protective effects on ovarian function. Similar to in many women with PCOS, DHT exposure led to reduced adiponectin levels, larger adipocyte size, and reduced insulin sensitivity in WTs. APNtg mice remained metabolically healthy despite DHT exposure, while APNko-DHT mice were even more insulin resistant than their DHT-exposed littermate WTs. DHT exposure also reduced the mRNA expression of genes involved in metabolic pathways in gonadal adipose tissue of WT and APNko, but this effect of DHT was not observed in APNtg mice. Moreover, APNtg-DHT mice displayed increased pancreatic mRNA levels of insulin receptors, Pdx1 and Igf1R, suggesting adiponectin stimulates beta cell viability/hyperplasia in the context of PCOS. In conclusion, adiponectin improves metabolic health but has only minor effects on reproductive functions in this PCOS-like mouse model.

Follicular fluid cerebellin and betatrophin regulate the metabolic functions of growing follicles in polycystic ovary syndrome

Objective

The aim of this study was to assess the changes of follicular fluid (FF) and serum levels of cerebellin precursor protein 1 (cbln1) and betatrophin in patients with polycystic ovary syndrome (PCOS) undergoing in vitro fertilization/intracytoplasmic sperm injection (IVF/ICSI) with a gonadotropin-releasing hormone (GnRH) antagonist protocol.

Methods

Twenty infertile women with PCOS and 20 control women diagnosed as poor responders undergoing ovarian stimulation with a GnRH antagonist were included. Blood samples were obtained during ovum pick-up. Follicular fluid from a dominant follicle was collected from the subjects. Using enzyme-linked immunosorbent assays, FF and serum levels of cbln1 and betatrophin were measured in both groups of participants. Metabolic and hormonal parameters were also determined and correlated with each other.

Results

Both groups of women had similar serum and FF betatrophin levels (55.0±8.9 ng/mL vs. 53.1±10.3 ng/mL, p=0.11). The serum and FF betatrophin levels of poor responders were found to be similar (49.9±5.9 ng/mL vs. 48.9±10.7 ng/mL, p=0.22). Conversely, the FF cbln1 levels of PCOS women were found to be significantly higher than the serum cbln1 levels (589.1±147.6 ng/L vs. 531.7±74.3 ng/L, p<0.02). The FF cbln1 levels of control participants without PCOS were significantly higher than their serum cbln1 levels (599.3±211.5 ng/L vs. 525.3±87.0 ng/L, p=0.01). Positive correlations were detected among body mass index, insulin resistance, serum insulin, total testosterone, and betatrophin levels in the PCOS group.

Conclusion

Follicular fluid betatrophin and cbln1 concentrations may play a pivotal role on follicular growth in PCOS subjects undergoing IVF/ICSI with an antagonist protocol.

Loss of PI3K p110α in the Adipose Tissue Results in Infertility and Delayed Puberty Onset in Male Mice

Deletion of PI3K catalytic subunit p110α in adipose tissue (aP2-Cre/p110α^flx/flx, α−/− hereafter) results in increased adiposity, glucose intolerance, and liver steatosis. Because this endocrine organ releases hormones like leptin, which are important in reproductive physiology, we investigated the reproductive phenotype of α−/− males. Compared to controls, α−/− males displayed delayed onset of puberty accompanied by a reduction in plasma LH levels and testicular weight. At postnatal day 30, α−/− mice exhibited normal body weight but elevated fasted plasma leptin levels. Testicular leptin gene expression was increased, whereas expression of the cholesterol transporter StAR and of P450 cholesterol side chain cleavage enzyme was decreased. Adult α−/− males were infertile and exhibited hyperandrogenemia with normal basal LH, FSH, and estradiol levels. However, neither sperm counts nor sperm motility was different between genotypes. The mRNA levels of leptin and of 17-beta-dehydrogenase 3, and enzyme important for testosterone production, were significantly higher in the testis of adult α−/− males. The mRNA levels of ERα, an important regulator of intratesticular steroidogenesis, were lower in the testis of adult and peripubertal α−/− males. We propose that chronic hyperleptinemia contributes to the negative impact that disrupting PI3K signaling in adipocytes has on puberty onset, steroidogenesis, and fertility in males.

Control of Germline Stem Cell Lineages by Diet and Physiology

Tight coupling of reproduction to environmental factors and physiological status is key to long-term species survival. In particular, highly conserved pathways modulate germline stem cell lineages according to nutrient availability. This chapter focuses on recent in vivo studies in genetic model organisms that shed light on how diet-dependent signals control the proliferation, maintenance, and survival of adult germline stem cells and their progeny. These signaling pathways can operate intrinsically in the germ line, modulate the niche, or act through intermediate organs to influence stem cells and their differentiating progeny. In addition to illustrating the extent of dietary regulation of reproduction, findings from these studies have implications for fertility during aging or disease states.

Genetic variation in leptin and leptin receptor genes as a risk factor for idiopathic male infertility

The aim of this study was to examine whether there is an association among genetic variability in leptin (LEP) and leptin receptor (LEPR) genes and male infertility. We performed a case-control study and were searching for an association between polymorphisms of LEP and LEPR genes and male infertility. The study group consisted of 317 patients with idiopathic infertility and a control group of 241 fertile men from Slovenia. Four single nucleotide polymorphisms (SNPs) in LEP gene and four single nucleotide polymorphisms (SNPs) in LEPR gene were chosen and genotyped. Statistically significant SNP was further validated in additional 255 infertile patients and 168 controls from Serbia and Macedonia. In the Slovenian population, we found a statistically significant difference in genotype distribution for rs10244329 polymorphism in LEP gene (recessive genotype model, p value = 0.048). The trend toward statistically significant difference in genotype distribution for rs10244329 polymorphism was confirmed in the Serbian and Macedonian populations (p value = 0.07). Our data suggest that genetic variability in the LEP gene might be associated with male infertility warranting further confirmation and mechanistic investigations.

Impact of Food Restriction on the Expression of the Adiponectin System and Genes in the Hypothalamic-Pituitary-Ovarian Axis of Pre-Pubertal Ewes

Adiponectin, a cytokine secreted typically by adipocytes, has been implicated as a molecular switch between female reproduction and energy balance. The present study was undertaken to investigate the expression of adiponectin system and patterns of genes in the hypothalamic-pituitary-ovary (HPO) axis of food-restricted pre-pubertal ewes. Eighteen 2-month-old female ewes were assigned to 3 groups after a pre-feeding ad libitum for 10 days (six in each group): the control group (C), the low-food-restricted group (LR) and the high-food-restricted group (HR), which were fed with 100%, 70% and 50% of ad libitum food intake, respectively. The hypothalamus, pituitary, ovary and serum were collected after food restriction for 2 months. Results by ELISA showed that food restriction increased serum adiponectin concentrations. Quantitative real-time PCR showed that the gene transcriptions for adiponectin receptor 1 (AdipoR1) and 2 (AdipoR2) were enhanced in the hypothalamic-pituitary-ovarian (HPO) axis, while KISS-1/GPR-54 and gonadotropin-releasing hormone (GnRH) in the hypothalamus and luteinizing hormone β-subunit (LHβ) and follicle-stimulating hormone β-subunit (FSHβ) in the pituitary were reduced after food restriction. Immunohistochemistry results demonstrated that AdipoR1 localized in the oocytes of follicles in the ovary. These results suggest that the alterations in the expression of adiponectin and its receptors in response to food restriction might negatively influence the HPO axis.

Adverse effects of perinatal nicotine exposure on reproductive outcomes

Nicotine exposure during pregnancy through cigarette smoking, nicotine replacement therapies or e-cigarette use continues to be a widespread public health problem, impacting both fetal and postnatal health. Yet, at this time, there remains limited data regarding the safety and efficacy in using these nicotine products during pregnancy. Notably, reports assessing the effect of nicotine exposure on postnatal health outcomes in humans, including reproductive health, are severely lacking. Our current understanding regarding the consequences of nicotine exposure during pregnancy is limited to a few animal studies, which do not comprehensively address the underlying cellular mechanisms involved. This paper aims to critically review the current knowledge from human and animal studies regarding the direct and indirect effects (e.g. obesity) of maternal nicotine exposure, regardless of its source, on reproductive outcomes in pregnancy and postnatal life. Furthermore, this review highlights several key cellular mechanisms involved in these adverse reproductive deficits including oxidative stress, inflammation, and endoplasmic reticulum (ER) stress. By understanding the interplay of the cellular mechanisms involved, further strategies could be developed to prevent the reproductive abnormalities resulting from exposure to nicotine in utero and influence informed clinical guidelines for pregnant women.