Leptin in reproduction

Integrated transcriptomic hypothalamic-pituitary-ovarian axis network analysis reveals the role of energy availability on egg production in layers

Energy is a crucial component for maintaining egg production in layers. The hypothalamic-pituitary-ovarian (HPO) axis is an energy-sensitive functional axis for follicle development, synthesis, and secretion of reproductive hormones, and plays a key role in modulating sustained ovulation in layers. To investigate the mechanism of integrated network regulation of the HPO axis under energy fluctuation, ninety Hy-line brown layers (265-day-old, 1.92 ± 0.02 kg) were randomly divided into three groups for a 17-day experiment: a control group (Con group) fed ad libitum from days 1 to 17, an energy-deprived group (ED group) that was fed ad libitum from days 1 to 12 and then underwent a fasting period from days 13 to 17 to induce a pause in laying, and a re-fed group (Rf group) that fasted for seven days (specifically, days 1 to 5, day 7, and day 9), had ad libitum access to feed on days 6 and 8, and was continuously fed from days 10 to 17. Each treatment consisted of 10 replicates with 3 birds per replicate. The study found that energy deprivation significantly decreased reproductive performance such as egg laying rate, ovarian index, number of small yellow follicles (SYF), and normal hierarchical follicles (NHIE) (P < 0.05), which recovered after refeeding, indicating the importance of energy availability for sustained ovulation in layers. In addition, estradiol (E2), estradiol to progesterone (E2/P4) ratio, and luteinizing hormone (LH) displayed changes similar to follicle number, whereas follicle-stimulating hormone (FSH) exhibited a contrasting pattern. Transcriptome analysis revealed that energy deprivation downregulated genes related to energy and appetite-regulated neurotransmitter receptors and neuropeptides in the hypothalamus. These signals combined to inhibit gonadotropin-releasing hormone (GnRH) secretion and subsequently downregulated the crucial genes responsible for synthesizing gonadotropins, gonadotropin-releasing hormone receptor (GnRHR), and glycoprotein hormones alpha chain (CGA). Consequently, this suppression of the hypothalamus and pituitary affected ovarian function through ovarian steroidogenesis and the extracellular matrix (ECM)-receptor interaction. These findings suggest that energy deprivation inhibits the function of the HPO axis, leading to impaired follicle development and reduced egg production, and that refeeding can partially restore these indicators.

Placental apoptosis increased by hypoxia inducible factor-1 stabilization is counteracted by leptin†

During pregnancy, apoptosis is a physiological event critical in the remodeling and aging of the placenta. Increasing evidence has pointed toward the relevance of hypoxia as modulator of trophoblast cell death. Previous reports have shown that leptin, a placental cytokine, promotes cell survival in both cell culture and placental explant models. The aim of this work is to establish the role of leptin in apoptosis under hypoxic condition in trophoblast cells. In this study, we evaluated the effect of cobalt chloride, a hypoxia mimicking agent that stabilizes the expression of hypoxia-inducible factor-1 alpha, on Swan-71 and human placental explants. Hypoxia chamber was also used to generate 2% oxygen. Apoptosis was determined by the presence of apoptotic nucleus, fragmentation of DNA and Caspase-3 and PARP-1 cleavage. The pro-apoptotic proteins BAX, BID, BAD, and BAK and the anti-apoptotic effectors BCL-2, B-cell lymphoma-extra-large, and myeloid cell leukemia-1 were also analyzed. We found that hypoxia-inducible factor-1 alpha stabilization increased the appearance of apoptotic nucleus, fragmentation of DNA, and Caspase-3 and PARP-1 cleavage. Hypoxia mimicking conditions enhanced the expression of pro-apoptotic effectors BAX, BID, BAD, and BAK. Hypoxia-inducible factor-1 alpha stabilization also downregulated the level of BCL-2, B-cell lymphoma-extra-large, and myeloid cell leukemia-1. All these apoptotic parameters changes were reversed with leptin treatment. Moreover, we showed that leptin action on apoptosis modulation involves PI3K and MAPK signaling pathways. Obtained data demonstrate that hypoxia-inducible factor-1 alpha stabilization induces apoptosis in human placenta and leptin counteracts this effect, reinforcing its role as a survival cytokine.

Leptin effects: focusing on the relationship between obesity and male infertility

The human male infertility has several causes interconnected to improper lifestyles such as smoking, sedentarism, environmental factors, toxins accumulation and energy imbalances. All these factors contribute to the obesity accompanied metabolic syndrome and hormonal alterations in the leptin-ghrelin axis. The leptin (Lep) has many pleiotropic effects in several biological systems, directly on the peripheral tissues or through the central nervous system. Many studies suggest that Lep is a key player in gonadal functions beside its documented role in reproductive regulation; however, further investigations are still necessary to elucidate all the molecular pathways involved in these mechanisms. Keeping into account that increased Lep levels in obese men are positively correlated with altered sperm parameters and testicular oxidative stress, evidence refers to Lep as a potential link between obesity and male infertility. This review represents an updated version on the concept of the Lep roles in mediating the male reproductive functions in obese patients.

Sequence identification and expression characterization of leptin in the spotted scat, Scatophagus argus

Scatophagus argus is an important marine culture fish in South and South-East Asia, including Southeast coastal areas of China. Artificial propagation technology for S. argus is not optimum; thus further studies on its reproduction biology are required. Although previous studies have shown that leptin (Lep) can regulate fish reproduction, the role of lep genes in S. argus is unknown. Herein, in silico analysis showed that S. argus has two lep genes (lepa and lepb). Protein 3D-structure prediction showed that Lepa has four α-helices (similar to mammals), while Lepb only has three. Tissue distribution analysis showed that lepa is highly expressed in the liver, whereas lepb was not detected in any tissue. Notably, lepr was expressed in all tissues. Lepa mRNA expression levels in the liver and serum Lep, estradiol (E2) and vitellogenin (Vtg) levels of female fish were significantly higher in ovaries at stage IV than in ovaries at stage II. Serum E2 levels were significantly positively correlated with Vtg levels in female fish at different development stages, while serum E2 was not correlated with Lep levels. Consistently, in vitro incubation of the liver with E2 significantly up-regulated vtga, while it did not affect lepa expression. Recombinant Lep (10 nM) significantly up-regulated chicken gonadotropin-releasing hormone (cGnRH/GnRH-II) in the hypothalamus and GnRH receptor (GnRHR) and luteinizing hormone beta (Lhb) in the pituitary. These results suggest that lepa regulates female reproduction in S. argus.

Role of Mediterranean diet in endocrine diseases: a joint overview by the endocrinologist and the nutritionist

PURPOSE

The purpose of this review is to examine the current evidence on the potential role of Mediterranean diet (MD) in the prevention and management of endocrine disorders and to highlight the importance of interdisciplinary collaboration between endocrinologists and nutritionists.

METHODS

A literature search was conducted using PubMed and Google Scholar databases to identify relevant studies published in English. Studies were selected based on their relevance to the role of MD in the prevention and management of endocrine disorders. The search terms included "Mediterranean diet," "endocrine disorders," "thyroid disorders," "gonadal disorders," and "neuroendocrine tumors".

RESULTS

The studies reviewed suggest that MD may have a beneficial effect in the prevention and management of various endocrine disorders, including thyroid disorders, gonadal disorders, and neuroendocrine tumors. MD has been associated with decreased risk of nodular thyroid disease and thyroid cancer, improved male and female reproductive health, and a potential role in the management of neuroendocrine tumors. MD's anti-inflammatory and antioxidant properties, as well as its high levels of phytochemicals, may play a role in its beneficial effects.

CONCLUSION

Interdisciplinary collaboration between endocrinologists and nutritionists is essential for the optimal management of endocrine disorders, including the potential role of MD in their prevention and management. While further research is needed, the current evidence suggests that MD may have a protective effect against endocrine disorders, and its incorporation into dietary recommendations may be beneficial.

Follicular fluid biomarkers for prediction of human IVF outcome in women with poor ovarian response

Background

The aim of controlled ovarian stimulation is to achieve an optimal number of mature oocytes to obtain good-quality embryos. High follicular fluid (FF) concentrations of FSH, hCG, and LH promote oocyte maturation and are associated with a higher probability of fertilization. LH concentrations in FF are consistently higher in follicles that will lead to a successful IVF outcome. The levels of some of these FF biomarkers may vary among different ovarian stimulation schemes; however, the effects of corifollitropin alfa, recombinant FSH (rFSH), LH (rLH), and highly purified urinary menotropins uhMG on these biomarkers are still unknown. The objective of this study was to characterize the profile of FF biomarkers (leptin, vascular endothelial growth factor (VEGF), metalloproteinases (MMPs), and NO2−/NO3−) according to three different protocols of controlled ovarian stimulation (COS) in poor ovarian responders (POR) and to evaluate the association between these profiles and clinical outcomes. Three groups of POR patients were examined according to the protocols used.

Results

Group C showed significant higher levels in all biomarkers (p < 0001). FF samples from Group B had the lowest levels of VEGF and Pro-MMP-9. Group A showed the lowest concentration of pro-MMP-2. The VEGF level and number of captured oocytes were positively correlated in Group C (r = 0.534, p = 0.01). MMP-9 and fertilization rate were negatively correlated in Group C (r = −0.476, p = 0.02). We found negative correlations between proMMP-2 and serum estradiol levels on the day of rhCG administration.

Conclusion

We found significant variations in the biomarker concentrations between the different controlled ovarian stimulation schemes used in POR patients. These differences can be potentially explained by the nature and composition of the gonadotropins. Our results support the hypothesis that some of these molecules should be thoroughly investigated as noninvasive predictors of egg quality.

Sexual and Reproductive Outcomes in Obese Fertile Men with Functional Hypogonadism after Treatment with Liraglutide: Preliminary Results

Purpose: To prospectively investigate the effects of treatment with liraglutide, a glucagon-like peptide 1 (GLP1) analog, on reproductive and sexual function in men with metabolic hypogonadism who are of childbearing age. Materials and Methods: To accomplish this purpose, 110 men of childbearing age (18-35 years) with metabolic hypogonadism were enrolled and divided into three groups, according to their desire to have children. Group A was made up of men actively seeking fatherhood, Group B, of men who did not seek fatherhood, and Group C, of men who had already fathered a child. Group A patients were treated with gonadotropins (urofollitropin at 150 IU, three times a week, and human chorionic gonadotropin at 2000 IU, twice a week), Group B patients with liraglutide (3 mg daily), and Group C patients with transdermal testosterone (60 mg per day). All patients were treated for 4 months. Results: Patients treated with liraglutide (Group B) showed significant improvement in conventional sperm parameters, compared to baseline and Group A patients, and in the quality of erectile function compared to baseline and patients of Groups A and C. In addition, they had significantly higher levels of total testosterone and sex hormone-binding globulin serum levels after 4 months of treatment with liraglutide than those achieved by patients in the other two groups at the end of the respective treatments. Finally, Group B patients also showed significantly higher serum gonadotropin levels than the other groups. Conclusions: The results of this study showed, for the first time, the efficacy of liraglutide, a GLP1 analog, for the pharmacological treatment of male patients with metabolic hypogonadism. Liraglutide has also shown advantages over traditional treatments on both reproductive and sexual function and appears to offer greater benefits in terms of metabolic protection. These findings suggest that liraglutide is a useful drug for the treatment of obese males with metabolic hypogonadism.

Leptin alleviated ovarian ischemia-reperfusion injury in rats via modulation of Sirt-1/Nrf2 and TLR4/NF-kB/caspase-3 signaling pathways

Objective. Ovarian torsion is a gynecological emergency that occurs mostly during the female reproductive years due to ovarian masses or surgical manipulation. This work aims to explore the probable protective effect of leptin on rat ovaries due to ischemia-reperfusion (IR) injury. Methods. Wistar albino rats were divided into four groups: 1) control group; 2) ovarian IR group (OVIR); 3) leptin group I [OVIR + leptin (10 µg/kg body weight, b.w.)]; and 4) leptin group II (OVIR + leptin (100 µg/kg b.w.)]. Serum levels of estradiol and anti-Mullerian hormone (AMH) were measured. Levels of oxidative stress and inflammatory markers in ovarian tissue were determined along with the expression of sirtuin 1 (Sirt1), nuclear erythroid factor-2 (Nrf2), cyclooxygenase-2 (COX-2), nuclear factor kappa (NF-κB), toll like receptor-4 (TLR4), and caspase-3. Results. Serum estradiol and AMH levels were decreased with increased expression of COX-2, TLR4, caspase-3, and NF-κB and decreased expression of Sirt1and Nrf2 in ovary of the OVIR group, which were improved by exogenous administration of both leptin doses. Conclusion. Leptin administration dose-dependently reduced the severity of OVIR injury via modulation of Sirt-1/Nrf2 and TLR4/NF-kB/caspase-3 signaling pathways. Thus, leptin may be used as an adjuvant measure to prevent ovarian damage and improve the outcomes. However, clinical studies are needed to evaluate these results in humans.

Male sex hormones, aging, and inflammation

Adequate levels of androgens (eugonadism), and specifically testosterone, are vital compounds for male quality of life, longevity, and positive health outcomes. Testosterone exerts its effects by binding to the androgen receptor, which is expressed in numerous tissues throughout the body. Significant research has been conducted on the impact of this steroid hormone on skeletal, muscle and adipose tissues and on the cardiovascular, immune, and nervous systems. Testosterone levels have also been studied in relation to the impact of diseases, aging, nutrition and the environment on its circulating levels. Conversely, the impact of testosterone on health has also been evaluated with respect to its cardiac and vascular protective effects, body composition, autoimmunity and all-cause mortality. The male aging process results in decreasing testosterone levels over time. The exact mechanisms and impact of these changes in testosterone levels with age on health- and life-span are still not completely clear. Further research is needed to determine the optimal testosterone and androgen levels to protect from chronic age-related conditions such as frailty and osteoporosis.

Obesity and male infertility: multifaceted reproductive disruption

Background

The global prevalence of obesity has soared to a concerning height in the past few decades. Interestingly, the global decline in semen quality is a parallel occurrence that urges researchers to evaluate if obesity is among the most essential causatives of male infertility or subfertility.

Main body

Obesity may alter the synchronized working of the reproductive-endocrine milieu, mainly the hypothalamic-pituitary-gonadal (HPG) axis along with its crosstalks with other reproductive hormones. Obesity-mediated impairment in semen parameters may include several intermediate factors, which include physical factors, essentially increased scrotal temperature due to heavy adipose tissue deposits, and systemic inflammation and oxidative stress (OS) initiated by various adipose tissue-derived pro-inflammatory mediators. Obesity, via its multifaceted mechanisms, may modulate sperm genetic and epigenetic conformation, which severely disrupt sperm functions. Paternal obesity reportedly has significant adverse effects upon the outcome of assisted reproductive techniques (ARTs) and the overall health of offspring. Given the complexity of the underlying mechanisms and rapid emergence of new evidence-based hypotheses, the concept of obesity-mediated male infertility needs timely updates and pristine understanding.

Conclusions

The present review comprehensively explains the possible obesity-mediated mechanisms, especially via physical factors, OS induction, endocrine modulation, immune alterations, and genetic and epigenetic changes, which may culminate in perturbed spermatogenesis, disrupted sperm DNA integrity, compromised sperm functions, and diminished semen quality, leading to impaired male reproductive functions.

Leptin secreted from testicular microenvironment modulates hedgehog signaling to augment the endogenous function of Leydig cells

Although testosterone deficiency (TD) may be present in one out of five men 40 years or older, the factors responsible for TD remain largely unknown. Leydig stem cells (LSCs) differentiate into adult Leydig cells (ALC) and produce testosterone in the testes under the pulsatile control of luteinizing hormone (LH) from the pituitary gland. However, recent studies have suggested that the testicular microenvironment (TME), which is comprised of Sertoli and peritubular myoid cells (PMC), plays an instrumental role in LSC differentiation and testosterone production under the regulation of the desert hedgehog signaling pathway (DHH). It was hypothesized that the TME releases paracrine factors to modulate LSC differentiation. For this purpose, cells (Sertoli, PMCs, LSCs, and ALCs) were extracted from men undergoing testis biopsies for sperm retrieval and were evaluated for the paracrine factors in the presence or absence of the TME (Sertoli and PMC). The results demonstrated that TME secretes leptin, which induces LSC differentiation and increases testosterone production. Leptin's effects on LSC differentiation and testosterone production, however, are inversely concentration-dependent: positive at low doses and negative at higher doses. Mechanistically, leptin binds to the leptin receptor on LSCs and induces DHH signaling to modulate LSC differentiation. Leptin-DHH regulation functions unidirectionally insofar as DHH gain or loss of function has no effect on leptin levels. Taken together, these findings identify leptin as a key paracrine factor released by cells within the TME that modulates LSC differentiation and testosterone release from mature Leydig cells, a finding with important clinical implications for TD.

Leptin and Its Signaling Are Not Involved in Zebrafish Puberty Onset

Leptin is a peptide hormone secreted from the adipose tissues and its signaling plays a central role in metabolic regulation of growth, especially on fat mass. In addition, leptin is also involved in regulating reproduction in mammals. In teleosts, there are two leptin ligands (lepa and lepb) and one cognate leptin receptor (lepr); however, their functions are still elusive. In this study, we created null-function mutants for lepa, lepb and lepr in zebrafish using CRISPR/Cas9 method and analyzed their phenotypes with emphasis on puberty onset, one major function widely reported for leptin in mammals. We demonstrated that the loss of leptin ligands or their receptor resulted in no obesity from prepubertal stage to adulthood. We then focused on leptin involvement in controlling puberty onset. We first confirmed the somatic threshold for puberty onset in females and proposed a criterion and somatic threshold for male puberty onset. We examined gonadal development and sex maturation in different genotypic combinations including single mutants (lepa−/−, lepb−/− and lepr−/−), double mutants (lepa−/−;lepb−/−) and triple mutants (lepa−/−;lepb−/−;lepr−/−). Our results showed that once the fish reached the thresholds, the siblings of all genotypes displayed comparable gonadal development in both sexes without obvious signs of changed puberty onset. In conclusion, this comprehensive genetic study on the lep-lepr system demonstrated that in contrast to its counterpart in mammals, leptin system plays little role in controlling growth and reproduction especially puberty onset in zebrafish.

Leptin receptor expression and its change in association with the normalization of EGF profile after seminal plasma treatment in repeat breeder dairy cows

Factors associated with high milk production levels have been linked to alterations in the endometrial epidermal growth factor (EGF) profile, a cause of reduced fertility in dairy cows. Therefore, we examined the leptin system that connects nutritional status and reproduction in dairy cattle related to reduced fertility in repeat breeder cows. Plasma leptin concentrations were measured in 18 heifers, 20 high-yielding control cows, and 26 repeat breeder cows, showing an altered EGF profile. Then, all repeat breeder cows were infused with seminal plasma (SP) into the vagina at the next estrus to normalize the EGF profile, while heifers and control cows were infused with vehicle alone. All animals were examined for EGF profiles. Eighteen repeat breeder cows, nine heifers, and nine control cows were also determined for leptin receptor (Ob-R) expression levels in the estrous cycle before and after the infusion. SP normalized the EGF profile in 53.8% of the repeat breeder cows. Leptin concentrations were similar in all groups, regardless of the treatment results for the EGF profile. In contrast, Ob-R levels in repeat breeder and control cows were similar and higher than those in heifers before SP treatment. Ob-R in repeat breeders showing a normal EGF profile after treatment decreased to an intermediate level between heifers and control cows and may provide a clue to take measures against repeat breeding in dairy cows.

Metabolic milieu and localization of ovarian leptin and receptor in queens under different reproduction phases

Metabolic profile and leptin presence and expression of receptor in the ovary of 8 queens were analyzed. All queens were assessed for nutritional state and underwent ovariectomy in accordance with Italian law for the control of stray cats and dogs. Three queens were at early gestation, three prepubescent and two non-pregnant. All animals appeared healthy but underweight. Haemogram and biochemical profile did not show to be of prognostic value. On microscopy, granulosa cells of secondary follicles tested positive to leptin in pregnant queens, while testing negative in non-pregnant ones. Muscular layer of vessels of the ovary in non-pregnant queens tested positive to receptor, but negative in those found pregnant. Results suggest that leptin is produced and receptor expressed in the different tissues of the ovary in underweight queens. Additionally, the expression of receptor did not necessarily imply local leptin production and clearly displayed to vary according to the reproduction phase. Taken altogether, these findings allow to conclude that the expression of receptor can be interpreted as the pillar bridging ovary tissues as target sites of circulating leptin produced elsewhere. Arguably, ovary removal may affect hormonal cross-talk at the systemic level, likely affecting different systemic functions, including the nutritional status.

Effect of weight loss on erectile function in men with overweight or obesity: A meta-analysis of randomised controlled trials

Obesity and overweight are independent risk factors of erectile dysfunction (ED). It is controversial whether weight loss can improve erectile function. We thereby performed this meta-analysis to clarify the therapeutic effect of weight loss on erectile function in overweight or obese men. Literature search was conducted on databases including Cochrane Library, Embase, Web of Science and PubMed to obtain all relevant English articles published before March 1, 2021. The primary outcome was final International Index of Erectile Function (IIEF) score or change in IIEF score. The secondary outcome was final body weight and body mass index (BMI) or change in body weight and BMI. After screening, 5 studies with 619 participants were enrolled in our meta-analysis. Our result showed that the mean difference in body weight between weight loss group and control group was -18.07 kg with p < .01, and the mean difference in BMI was -9.6 kg/m² with p < .01. The mean difference of IIEF between weight loss group and control group was 1.99 with p < .01. This meta-analysis showed that weight loss could improve erectile function in overweight or obese men. Losing weight could serve as an adjuvant therapy for ED.

Reduced Endothelial Leptin Signaling Increases Vascular Adrenergic Reactivity in a Mouse Model of Congenital Generalized Lipodystrophy

The adipokine leptin, which is best-known for its role in the control of metabolic function, is also a master regulator of cardiovascular function. While leptin has been approved for the treatment of metabolic disorders in patients with congenital generalized lipodystrophy (CGL), the effects of chronic leptin deficiency and the treatment on vascular contractility remain unknown. Herein, we investigated the effects of leptin deficiency and treatment (0.3 mg/day/7 days) on aortic contractility in male Berardinelli-Seip 2 gene deficient mice (gBscl2^-/-, model of CGL) and their wild-type control (gBscl2^+/+), as well as in mice with selective deficiency in endothelial leptin receptor (LepR^EC-/-). Lipodystrophy selectively increased vascular adrenergic contractility via NO-independent mechanisms and induced hypertrophic vascular remodeling. Leptin treatment and Nox1 inhibition blunted adrenergic hypercontractility in gBscl2^-/- mice, however, leptin failed to rescue vascular media thickness. Selective deficiency in endothelial leptin receptor did not alter baseline adrenergic contractility but abolished leptin-mediated reduction in adrenergic contractility, supporting the contribution of endothelium-dependent mechanisms. These data reveal a new direct role for endothelial leptin receptors in the control of vascular contractility and homeostasis, and present leptin as a safe therapy for the treatment of vascular disease in CGL.

Safflower seed oil improves steroidogenesis and spermatogenesis in rats with type II diabetes mellitus by modulating the genes expression involved in steroidogenesis, inflammation and oxidative stress

ETHNOPHARMACOLOGICAL RELEVANCE

Diabetes mellitus (DM), as a multiorgan syndrome, is an endocrine and metabolic disorder that is associated with male reproductive system dysfunction and infertility. Safflower (Carthamus tinctorius L.) as an herbal remedy improves DM and infertility-related disorders. The anti-hypercholesterolemic, anti-inflammatory, and antioxidative properties of this herb have been well documented, but its role in testosterone production, male reproductive system and zinc homeostasis has not been fully illustrated.

AIM OF THE STUDY

This study aimed to investigate the preventive and therapeutic properties of different doses of safflower seed oil against reproductive damage caused by type II DM by investigating zinc element homeostasis, inflammation and oxidative damage in testis tissue and their relationship with testosterone production and sperm parameters.

MATERIALS AND METHODS

Eighty adult male Sprague-Dawley rats were randomly divided into eight groups and treated daily for 12 and 24 weeks in protective and therapeutic studies, respectively. Type II DM was induced by a High Fat Diet (HFD) in normoglycemic rats for three months. At the end of each study, serum level of glucose, testosterone, gonadotropins, TNF-α, insulin, and leptin were measured. Moreover, antioxidant enzymes activity, lipid peroxidation, zinc and testosterone along with the expression of Nrf-2, NF-κB, TNF-α, StAR, P450scc, and 17βHSD3 genes in the testis were detected.

RESULTS

After the intervention, the activity of antioxidant enzymes and the level of testosterone and gonadotropins significantly decreased in the rats with DM in comparison to the others. However, lipid peroxidation and serum level of insulin, leptin and TNF-α increased and the testicular level of zinc significantly changed in the rats with DM compared to the control groups (p < 0.05). The gene expression of NF-κB and TNF-α were also significantly increased and the gene expression of Nrf2, StAR, P450scc and 17βHSD3 were decreased in the testis of diabetic rats (p < 0.05). The results showed that pretreatment and treatment with safflower seed oil could improve these parameters in diabetic rats compared with untreated diabetic rats (p < 0.05).

CONCLUSION

HFD could impair the production of testosterone and sperm, and reduce gonadotropin by increasing the serum level of leptin and inducing insulin resistance, oxidative stress and inflammation. However, safflower oil in a dose-dependent manner could improve testosterone level and sperm parameters by improving the level of leptin, zinc and insulin resistance, and the genes expression involved in testosterone synthesis, inflammation and oxidative stress.

Leptin, Both Bad and Good Actor in Cancer

Leptin is an important regulator of basal metabolism and food intake, with a pivotal role in obesity. Leptin exerts many different actions on various tissues and systems, including cancer, and is considered as a linkage between metabolism and the immune system. During the last decades, obesity and leptin have been associated with the initiation, proliferation and progression of many types of cancer. Obesity is also linked with complications and mortality, irrespective of the therapy used, affecting clinical outcomes. However, some evidence has suggested its beneficial role, called the "obesity paradox", and the possible antitumoral role of leptin. Recent data regarding the immunotherapy of cancer have revealed that overweight leads to a more effective response and leptin may probably be involved in this beneficial process. Since leptin is a positive modulator of both the innate and the adaptive immune system, it may contribute to the increased immune response stimulated by immunotherapy in cancer patients and may be proposed as a good actor in cancer. Our purpose is to review this dual role of leptin in cancer, as well as trying to clarify the future perspectives of this adipokine, which further highlights its importance as a cornerstone of the immunometabolism in oncology.

The Importance of Leptin to Reproduction

A healthy nutritional state is required for all aspects of reproduction and is signaled by the adipokine leptin. Leptin acts in a relatively narrow concentration range: too much or too little will compromise fertility. The leptin signal timing is important to prepubertal development in both sexes. In the brain, leptin acts on ventral premammillary neurons which signal kisspeptin (Kiss1) neurons to stimulate gonadotropin releasing hormone (GnRH) neurons. Suppression of Kiss1 neurons occurs when agouti-related peptide neurons are activated by reduced leptin, because leptin normally suppresses these orexigenic neurons. In the pituitary, leptin stimulates production of GnRH receptors (GnRHRs) and follicle-stimulating hormone at midcycle, by activating pathways that derepress actions of the messenger ribonucleic acid translational regulatory protein Musashi. In females, rising estrogen stimulates a rise in serum leptin, which peaks at midcycle, synchronizing with nocturnal luteinizing hormone pulses. The normal range of serum leptin levels (10-20 ng/mL) along with gonadotropins and growth factors promote ovarian granulosa and theca cell functions and oocyte maturation. In males, the prepubertal rise in leptin promotes testicular development. However, a decline in leptin levels in prepubertal boys reflects inhibition of leptin secretion by rising androgens. In adult males, leptin levels are 10% to 50% of those in females, and high leptin inhibits testicular function. The obesity epidemic has elucidated leptin resistance pathways, with too much leptin in either sex leading to infertility. Under conditions of balanced nutrition, however, the secretion of leptin is timed and regulated within a narrow level range that optimizes its trophic effects.

Comparative genomics of cetartiodactyla: energy metabolism underpins the transition to an aquatic lifestyle

Foraging disruption caused by human activities is emerging as a key issue in cetacean conservation because it can affect nutrient levels and the amount of energy available to individuals to invest into reproduction. Our ability to predict how anthropogenic stressors affect these ecological processes and ultimately population trajectory depends crucially on our understanding of the complex physiological mechanisms that detect nutrient availability and regulate energy metabolism, foraging behavior and life-history decisions. These physiological mechanisms are likely to differ considerably from terrestrial mammalian model systems. Here, we examine nucleotide substitution rates in cetacean and other artiodactyl genomes to identify signatures of selection in genes associated with nutrient sensing pathways. We also estimated the likely physiological consequences of adaptive amino acid substitutions for pathway functions. Our results highlight that genes involved in the insulin, mTOR and NF-ĸB pathways are subject to significant positive selection in cetaceans compared to terrestrial artiodactyla. These genes may have been positively selected to enable cetaceans to adapt to a glucose-poor diet, to overcome deleterious effects caused by hypoxia during diving (e.g. oxidative stress and inflammation) and to modify fat-depot signaling functions in a manner different to terrestrial mammals. We thus show that adaptation in cetaceans to an aquatic lifestyle significantly affected functions in nutrient sensing pathways. The use of fat stores as a condition index in cetaceans may be confounded by the multiple and critical roles fat has in regulating cetacean metabolism, foraging behavior and diving physiology.

Relationship between Prenatal Characteristics and Body Condition and Endocrine Profile in Rabbits

Simple Summary

Litter size is an essential trait in rabbit production, and it depends on ovulation rate and embryonic and foetal survival. The period between 8 and 18 d of gestation is critical for foetal survival, as the placenta controls foetal nutrition during this period. Ovulation rate and foetal survival at 12 d of gestation are affected by body condition and metabolic and hormonal profile. Higher foetal survival is related to a higher number of vessels arriving at the implantation site, and may be due to higher available space for the foetus.

Abstract

This study evaluated the relationship between prenatal characteristics and body condition and endocrine profile. A total of 25 non-lactating multiparous females were used. Body condition, measured as body weight and perirenal fat thickness, non-esterified fatty acids (NEFA), leptin, progesterone and 17β-estradiol were recorded at mating and 12 d of gestation. Ovulation rate, number of foetuses, ovary and foetal weight, length and weight of uterine horn, available space per foetus and maternal and foetal placental morphometry were recorded at 12 d of gestation. Ovulation rate showed a positive linear relationship with number of foetuses, ovary weight and NEFA. A negative linear relationship between ovulation rate and perirenal fat thickness and leptin was obtained. Ovulation rate was maximum when body weight and 17β-estradiol were 4.4 kg and 22.7 pg/mL, respectively. Foetal weight showed a positive relationship with perirenal fat thickness and a negative relationship with leptin. An increase in progesterone and NEFA concentration was related to a positive linear increase in number of foetuses and in uterine horn weight. Space available per foetus was affected both by the number of vessels that reach the implantation site and by position of the foetus in the uterine horn. In conclusion, body condition during mating and early gestation should be maintained within an optimal range to ensure the best prenatal characteristics. While 17β-estradiol, NEFA and leptin affected the ovulation rate, progesterone and NEFA affected foetal development. The number of vessels that reach the implantation site determines early foetal survival.

Caloric restriction in female reproduction: is it beneficial or detrimental?

Caloric restriction (CR), an energy-restricted intervention with undernutrition instead of malnutrition, is widely known to prolong lifespan and protect against the age-related deteriorations. Recently it is found that CR significantly affects female reproduction via hypothalamic (corticotropin releasing hormone, neuropeptide Y, agouti-related peptide) and peripheral (leptin, ghrelin, insulin, insulin-like growth factor) mediators, which can regulate the energy homeostasis. Although CR reduces the fertility in female mammals, it exerts positive effects like preserving reproductive capacity. In this review, we aim to discuss the comprehensive effects of CR on the central hypothalamus-pituitary-gonad axis and peripheral ovary and uterus. In addition, we emphasize the influence of CR during pregnancy and highlight the relationship between CR and reproductive-associated diseases. Fully understanding and analyzing the effects of CR on the female reproduction could provide better strategies for the management and prevention of female reproductive dysfunctions.

Polycystic Ovary Disease and Obesity: Leptin, Weight-loss Medication, and Bariatric Surgery

For many patients, weight loss is a first-line measure recommended to reduce comorbidities associated with polycystic ovary disease. When lifestyle modifications such as diet and exercise are insufficient at achieving this goal, the addition of weight loss medications has proven effective for many patients. In patients with severe obesity, bariatric surgery is often used when other methods have been unsuccessful and has shown promising results for improving health and fertility in patients with polycystic ovary disease.

Somatotropic-Testicular Axis: A crosstalk between GH/IGF-I and gonadal hormones during development, transition, and adult age

BACKGROUND

The hypothalamic-pituitary-gonadal (HPG) and hypothalamic-pituitary-somatotropic (HPS) axes are strongly interconnected. Interactions between these axes are complex and poorly understood. These interactions are characterized by redundancies in reciprocal influences at each level of regulation and the combination of endocrine and paracrine effects that change during development.

OBJECTIVES

To comprehensively review the crosstalk between the HPG and HPS axes and related pathological and clinical aspects during various life stages of male subjects.

MATERIALS AND METHODS

A thorough search of publications available in PubMed was performed using proper keywords.

RESULTS

Molecular studies confirmed the expressions of growth hormone (GH) and insulin-like growth factor-I (IGF-I) receptors on the HPG axis and reproductive organs, indicating a possible interaction between HPS and HPG axes at various levels. Insulin growth factors participate in sexual differentiation during fetal development, indicating that normal HPS axis activity is required for proper testicular development. IGF-I contributes to correct testicular position during minipuberty, determines linear growth during childhood, and promotes puberty onset and pace through gonadotropin-releasing hormone activation. IGF-I levels are high during transition age, even when linear growth is almost complete, suggesting its role in reproductive tract maturation. Patients with GH deficiency (GHD) and insensitivity (GHI) exhibit delayed puberty and impaired genital development; replacement therapy in such patients induces proper pubertal development. In adults, few studies have suggested that lower IGF-I levels are associated with impaired sperm parameters.

DISCUSSION AND CONCLUSION

The role of GH-IGF-I in testicular development remains largely unexplored. However, it is important to evaluate gonadic development in children with GHD. Additionally, HPS axis function should be evaluated in children with urogenital malformation or gonadal development alterations. Correct diagnosis and prompt therapeutic intervention are needed for healthy puberty, attainment of complete gonadal development during transition age, and fertility potential in adulthood.

Time-restricted feeding improves the reproductive function of female mice via liver fibroblast growth factor 21

Background

There has been a significant increase, to epidemic levels, of obese and overweight women of reproductive age, causing impairments to reproductive health. Time‐restricted feeding (TRF) including isocaloric intake has shown to be preventive of obesity‐related disorders. However, its therapeutic ability to improve the reproductive function of female remains largely unknown.

Methods

Here, we investigated the ability of TRF to improve the reproductive function in wild‐type and liver‐specific FGF21 knockout female mice. To study fertility, a continuous and a short‐term fertility test, gonadotropin releasing‐hormone (GnRH), and Kisspeptin test were performed. Immortalized GnRH neuron was used to examine the direct role of liver fibroblast growth factor 21 (FGF21) on GnRH secretion.

Results

We found that TRF rescues female mice from bodyweight gain and glucose intolerance, as well as ovarian follicle loss and dysfunction of estrus cyclicity induced by high‐fat diet. Furthermore, the beneficial effects of the TRF regimen on the reproductive performance were also observed in mice fed both chow and high‐fat diet. However, those beneficial effects of TRF on metabolism and reproduction were absent in liver‐specific FGF21 knockout mice. In vitro, FGF21 directly acted on GnRH neurons to modulate GnRH secretion via extracellular regulated protein kinases (ERK_1/2) pathway.

Conclusions

Overall, time‐restricted feeding improves the reproductive function of female mice and liver FGF21 signaling plays a key role in GnRH neuron activity in female mice.

Blood level of adipokines and nutritional status variables in adolescent pregnancy

Objective

To evaluate the serum levels of adiponectin and leptin and their relationship with nutritional variables during pregnancy in adolescents.

Methods

This prospective cohort study evaluated eutrophic pregnant adolescents (body mass index [BMI], 18.5–24.9 kg/m²) during the 3 gestational trimesters (first, 10–14 weeks; second, 24–28 weeks; and third, 30–34 weeks). Serum adiponectin and leptin concentrations were measured using the enzyme-linked immunosorbent assay method. The relationship of these adipokines with the pre-gestational BMI, gestational weight gain, weight at the time of sample collection, and newborn weight were evaluated. Analysis of variance and the Kruskal-Wallis test were used for statistical analysis.

Results

The study group comprised 62 pregnant adolescents. The serum concentration of adiponectin showed a significant difference between the first and third trimesters (P=0.003), which decreased during pregnancy, but unrelated to nutritional variables. Serum leptin levels increased throughout the pregnancy (P<0.0001) and showed a positive correlation with pre-gestational BMI, total weight gain, pregnancy weight at the time of sample collection, and newborns’ weight.

Conclusion

Serum levels of adiponectin and leptin vary inversely throughout pregnancy. This pattern in adolescents is similar to that observed in adults. Moreover, leptin concentrations increased throughout pregnancy, and they were positively correlated with all variables evaluated.

Sexual dysfunction and central obesity in patients with first episode psychosis

Background

In recent years the association between sexual dysfunction (SD) and obesity in the general population has drawn major attention. Although sexual dysfunction is common in psychosis, its relationship with weight gain and obesity remains unclear.

Aims

To investigate the association between sexual dysfunction and obesity in a cohort of patients with first episode psychosis.

Method

Sexual function was assessed in a cohort of patients with first episode psychosis using the Sexual Function Questionnaire (SFQ). Anthropometric measures, including weight, BMI, waist, waist–hip ratio were investigated. Additionally, leptin and testosterone were investigated in male patients.

Results

A total of 116 patients (61 males and 55 females) were included. Of these 59% of males and 67.3% of females showed sexual dysfunction (SD) according to the SFQ. In males, higher SFQ scores were significantly correlated with higher BMI (Std. β = 0.36, P = 0.01), higher leptin levels (Std. β = 0.34, P = 0.02), higher waist–hip ratio (Std. β = 0.32, P = 0.04) and lower testosterone levels (Std. β = −0.44, P = 0.002). In contrast, in females, SFQ scores were not associated with any of these factors.

Conclusions

While sexual dysfunction is present in both female and male patients with their first episode of psychosis, only in males is sexual dysfunction associated with increased BMI and waist–hip ratio. The association between SD, BMI, low levels of testosterone and high levels of leptin suggest that policies that lead to healthier diets and more active lifestyles can be beneficial at least, to male patients.

Relationship of Serum Leptin and Reproductive Hormones in Unexplained Infertile and Fertile Females

OBJECTIVE

To investigate the relationship between serum leptin and reproductive hormones in females with unexplained infertility (UI).

METHODOLOGY

It was a case-control study conducted in the Gynecology and Obstetrics Department and Infertility Clinic, Jinnah Postgraduate Medical Center (JPMC), Karachi, Pakistan. A total of 235 primary infertile females with an unidentified cause of infertility were selected from the Infertility Clinics. The patients were excluded if they were found to have polycystic ovary syndrome, endometriosis, tubal blockage, irregular menstrual cycles, hyperthyroidism, hypothyroidism, hyperprolactinemia, hyperandrogenemia, fasting blood sugar >110 mg/dl, and male factor infertility. A total of 205 healthy, fertile females were selected from the general population. The blood samples of both groups were collected on the 12th and 21st day of their menstrual cycle. Serum leptin, follicle-stimulating hormone (FSH), luteinizing hormone (LH), and E2 levels were measured. Statistical analysis was executed using the SPSS version 16 (SPSS Inc., Chicago, IL).

RESULTS

No significant difference was observed in leptin values of fertile and UI females, 37.110±1.19 vs. 35.321±0.901. In the preovulatory phase (12th day) of the cycle, infertile subjects with body mass index (BMI) <20 and 20-24.9 had significantly higher values for leptin (p<0.05), whereas, with an increase in BMI, leptin levels were reduced in these females. Leptin was reduced further in the luteal phase of infertile females with BMI 25-30, with a significantly lower value for FSH (p<0.005), LH (p<0.005), and estradiol (p<0.005. In infertile subjects, it correlated with estradiol (r=0.501, p<0.005), BMI (r=0.903, p<0.001), and progesterone (r=0.146, p<0.05).

CONCLUSION

Low levels of leptin observed to have an increase in the BMI of UI females were associated with a reduced estradiol and progesterone production in the luteal phase of the cycle.

The expressions of some metabolic hormones (leptin, ghrelin and obestatin) in the tissues of sheep tongue

In this study, we aimed to observe the localization and expression of peptide hormones-leptin, ghrelin and obestatin-in the sheep tongue by immunohistochemistry. For that purpose, tongues of ten adult sheep were used. Leptin expression of moderate intensity was observed in the basal and parabasal epithelial cells of the luminal epithelium, and leptin was strongly expressed in the taste buds of the circumvallate and fungiform papillae and in von Ebner's glands. Ghrelin was primarily expressed in some of the skeletal muscle cells and the smooth muscle cells of the middle layer of blood vessels. A strong expression was observed in the epithelial cells lining the base of the groove surrounding the circumvallate papillae. Obestatin expression was particularly strong in the epithelial cells of the salivary ducts. It was also stronger in the von Ebner's glands than in the seromucous glands. Leptin, ghrelin and obestatin were shown to be produced at varying levels in different cell types, including epithelial, stromal and skeletal muscle cells, as well as in ganglion neurons, neural plexuses and blood vessels in the sheep tongue. Cellular localization and expression of these peptide hormones have not been investigated in many species including sheep.

Functional Relationship between Leptin and Nitric Oxide in Metabolism

Leptin, the product of the ob gene, was originally described as a satiety factor, playing a crucial role in the control of body weight. Nevertheless, the wide distribution of leptin receptors in peripheral tissues supports that leptin exerts pleiotropic biological effects, consisting of the modulation of numerous processes including thermogenesis, reproduction, angiogenesis, hematopoiesis, osteogenesis, neuroendocrine, and immune functions as well as arterial pressure control. Nitric oxide (NO) is a free radical synthesized from L-arginine by the action of the NO synthase (NOS) enzyme. Three NOS isoforms have been identified: the neuronal NOS (nNOS) and endothelial NOS (eNOS) constitutive isoforms, and the inducible NOS (iNOS). NO mediates multiple biological effects in a variety of physiological systems such as energy balance, blood pressure, reproduction, immune response, or reproduction. Leptin and NO on their own participate in multiple common physiological processes, with a functional relationship between both factors having been identified. The present review describes the functional relationship between leptin and NO in different physiological processes.

Computational and artificial neural network based study of functional SNPs of human LEPR protein associated with reproductive function

Genetic polymorphisms are mostly associated with inherited diseases, detecting and analyzing the biological significance of functional single-nucleotide polymorphisms (SNPs) using wet laboratory experiments is an arduous task hence the computational analysis of putative SNPs is essential before conducting a study on a large population. SNP in the leptin receptor (LEPR) could result in the retention of intracellular signalling due to the structural and functional instability of the receptor causing abnormal reproductive function in human. In this first comprehensive computational analysis of LEPR gene mutation, we have identified and analyzed the functional consequence and structural significance of the SNPs in LEPR using recently developed several computational algorithms. Thirteen deleterious mutations such as W13C, S93G, I232R, Q307H, Y354C, E497A, Q571H, R612H, K656N, T690A, T699M V741M, and L760R were identified in the LEPR gene coding region. Backpropagation algorithm has been developed to forestall the deleterious nature of SNP and to validate the outcome of the tested computational tools. From ConSurf prediction three SNPs (Q571H, R612H, and T699M) were highly conserved on LEPR protein and the most deleterious variant R612H had one hydrogen bond abolished and severely reduced protein stability. Molecular docking suggested that the mutant (R612H) LEPR had lowest binding energy than native LEPR with the ligand molecule. Thus the energetically destructive changeover of ARG to HIS in R612H could possibly affect the LEPR protein structural stability and functional constancy due to interruption in the amino acid interactions and could result in reproductive disorders in human and increases the complication in obstetric and pregnancy outcome.

The Role of Leptin and Adiponectin in Obesity-Associated Cognitive Decline and Alzheimer's Disease

Cross-talk between adipose tissue and central nervous system (CNS) underlies the increased risk of obese people to develop brain diseases such as cognitive and mood disorders. Detailed mechanisms for how peripheral changes caused by adipose tissue accumulation in obesity impact the CNS to cause brain dysfunction are poorly understood. Adipokines are a large group of substances secreted by the white adipose tissue to regulate a wide range of homeostatic processes including, but not limited to, energy metabolism and immunity. Obesity is characterized by a generalized change in the levels of circulating adipokines due to abnormal accumulation and dysfunction of adipose tissue. Altered adipokine levels underlie complications of obesity as well as the increased risk for the development of obesity-related comorbidities such as type 2 diabetes, cardiovascular and neurodegenerative diseases. Here, we review the literature for the role of adipokines as key mediators of the communication between periphery and CNS in health and disease. We will focus on the actions of leptin and adiponectin, two of the most abundant and well studied adipokines, in the brain, with particular emphasis on how altered signaling of these adipokines in obesity may lead to cognitive dysfunction and augmented risk for Alzheimer's disease. A better understanding of adipokine biology in brain disorders may prove of major relevance to diagnostic, prevention and therapy.

The expression and distribution of a leptin receptor in the central nervous system, digestive organs, and gonads of the giant freshwater prawn, Macrobrachium rosenbergii

In the present study, the presence and distribution of leptin receptor (LEP-R) in central nervous system, digestive organs, gonads of giant freshwater prawn, Macrobrachium rosenbergii, were investigated with Western blot and immunohistochemistry. By Western blot a LEP-R with a molecular weight (MW) of 100 kDa was detected in the brain, thoracic ganglia, abdominal ganglia, hepatopancreas, all parts of the gastrointestinal tract, ovaries, and testes. In hepatopancreas and foregut, another intense positive band was detected at molecular weight of 30 kDa, which could be an isotype of LEP-R. By immunohistochemistry, LEP-R-ir was detected in the neurons, and neuropils in the brain, thoracic ganglia, and abdominal ganglia. In the gastrointestinal tract, there was intense LEP-R-ir in the apical part of the epithelial cells of the foregut, midgut, and hindgut. In addition, LEP-R-ir was found in the Restzellen(R)cells and Fibrillenzellen(F) cells in the hepatopancreas. In the ovary, LEP-R-ir was detected in early stage of oocytes and mature oocytes. Intense LEP-R-ir was observed in spermatogonia and spermatocytes of the small and orange claw male prawns. In addition, LEP-R was seen in the high epithelium of spermatic ducts from all male morphotypes. In summary, the detection of the LEP-R-ir suggests the existence of a LEP-R in several organs of M. rosenbergii. Through binding with leptin peptide, LEP-R may be an important signaling molecule that has critical functions in modulating and controlling food intake, energy expenditure, and reproduction in this prawn.

Leptin Regulation of Gonadotrope Gonadotropin-Releasing Hormone Receptors As a Metabolic Checkpoint and Gateway to Reproductive Competence

The adipokine leptin signals the body's nutritional status to the brain, and particularly, the hypothalamus. However, leptin receptors (LEPRs) can be found all throughout the body and brain, including the pituitary. It is known that leptin is permissive for reproduction, and mice that cannot produce leptin (Lep/Lep) are infertile. Many studies have pinpointed leptin's regulation of reproduction to the hypothalamus. However, LEPRs exist at all levels of the hypothalamic-pituitary-gonadal axis. We have previously shown that deleting the signaling portion of the LEPR specifically in gonadotropes impairs fertility in female mice. Our recent studies have targeted this regulation to the control of gonadotropin releasing hormone receptor (GnRHR) expression. The hypotheses presented here are twofold: (1) cyclic regulation of pituitary GnRHR levels sets up a target metabolic checkpoint for control of the reproductive axis and (2) multiple checkpoints are required for the metabolic signaling that regulates the reproductive axis. Here, we emphasize and explore the relationship between the hypothalamus and the pituitary with regard to the regulation of GnRHR. The original data we present strengthen these hypotheses and build on our previous studies. We show that we can cause infertility in 70% of female mice by deleting all isoforms of LEPR specifically in gonadotropes. Our findings implicate activin subunit (InhBa) mRNA as a potential leptin target in gonadotropes. We further show gonadotrope-specific upregulation of GnRHR protein (but not mRNA levels) following leptin stimulation. In order to try and understand this post-transcriptional regulation, we tested candidate miRNAs (identified with in silico analysis) that may be binding the Gnrhr mRNA. We show significant upregulation of one of these miRNAs in our gonadotrope-Lepr-null females. The evidence provided here, combined with our previous work, lay the foundation for metabolically regulated post-transcriptional control of the gonadotrope. We discuss possible mechanisms, including miRNA regulation and the involvement of the RNA binding protein, Musashi. We also demonstrate how this regulation may be vital for the dynamic remodeling of gonadotropes in the cycling female. Finally, we propose that the leptin receptivity of both the hypothalamus and the pituitary are vital for the body's ability to delay or slow reproduction during periods of low nutrition.

The levels of adipokines in relation to hormonal changes during the menstrual cycle in young, normal-weight women

CONTEXT

The aim of this study was to assess the plasma leptin, adiponectin, resistin, visfatin/NAMPT, omentin-1, vaspin, apelin, TNF-α, IL-6 and RBP4 levels in relation to hormonal changes during the menstrual cycle in young, healthy, normal-weight women.

METHODS

The study involved 52 young, healthy, normal-weight women. Anthropometric parameters, body composition and levels of plasma leptin, adiponectin, resistin, visfatin/NAMPT, omentin-1, vaspin, apelin, TNF-α, IL-6 and RBP4 in addition to serum FSH, LH, estradiol, progesterone, 17-OH progesterone, androgens, SHBG and insulin concentrations were measured during a morning in fasting state three times: between days 2-4, days 12-14 and days 24-26 of the menstrual cycle.

RESULTS

Plasma adiponectin, omentin-1, resistin and visfatin/NAMPT, apelin, TNF-α, IL-6 and RBP4 concentrations were stable during the menstrual cycle, while leptin and vaspin levels were significantly higher in both the midcycle and the luteal phases than those in the follicular phase. Multivariate regression analyses revealed that changes in leptin and vaspin levels between the follicular and the luteal phase are strongly related to changes in total testosterone levels.

CONCLUSIONS

Our results revealed stable levels of adipokines during the phases of the physiological menstrual cycle, except for leptin and vaspin, which showed increased levels in both the midcycle and the luteal phases. This effect was significantly associated with changes in the secretion of testosterone, 17-OH progesterone and insulin in the luteal phase.

Circulating leptin and adiponectin, and breast density in premenopausal Mexican women: the Mexican Teachers' Cohort

PURPOSE

Leptin and adiponectin are produced by the adipose tissue. Mammographic density (MD) is one of the strongest predictors of breast cancer (BC) and is highly influenced by adiposity. How the interplay between MD, obesity, and obesity-related biomarkers influences BC risk, however, is still unknown, especially in premenopausal women, where adiposity seems to be protective for BC. The aim of the present study was to explore the association between circulating leptin, adiponectin, and their ratio, with MD in Mexican premenopausal women who are part of the large Mexican Teachers' Cohort (MTC).

METHODS

A subsample of 2,084 women from the MTC participated in a clinical evaluation. Of them, 574 premenopausal women were randomly selected, from four MD strata. Serum leptin and adiponectin concentrations were measured by immunoassays. Multivariate regression analyses were performed to compare means of MD by quartiles of adipokines and their ratio.

RESULTS

High leptin and leptin/adiponectin ratio levels were significantly associated with lower percentage MD and higher absolute and non-absolute dense tissue areas. High adiponectin levels were significantly associated with lower absolute dense and non-dense tissue areas, but not with percentage MD. After adjustment for BMI, only the associations between percentage MD and absolute non-dense tissue area with leptin remained statistically significant.

CONCLUSIONS

Leptin, adiponectin, and their ratio were associated with MD; however, only the positive association with leptin seemed to be independent from overall obesity.

Semicarbazide disturbs the reproductive system of male zebrafish (Danio rerio) through the GABAergic system

Semicarbazide (SMC), an emerging water contaminant, exerts anti-estrogenic effects in female zebrafish. However, the exact influence of SMC on male reproduction remains unclear. In this study, adult male zebrafish were exposed to 1-1000μg/L SMC in a semi-static system for 28 d prior to examining the testicular somatic index (TSI), testis histology, plasma sex hormone levels, and the transcription of genes involved in reproduction. The results showed that testicular morphology was altered and TSI was down-regulated by high concentrations of SMC (≥100μg/L and 1000μg/L, respectively). Plasma testosterone and 17β-estradiol concentrations were significantly decreased by all of the SMC treatments, along with down-regulation of the corresponding steroidogenic gene transcripts. These changes were associated with the inhibition of gamma-aminobutyric acid synthesis and function, in addition to the decreased expression of reproductive regulators. Our results contribute to elucidating the mechanisms underlying the adverse reproductive effects of SMC in male zebrafish.

High DHEAS Is Associated With Earlier Pubertal Events in Girls But Not in Boys

Context:

Premature adrenarche (PA) has been associated with increased metabolic risk.

Objective:

To describe the risk of precocious thelarche (PT; <8 years), pubarche (PP; girls <8 years, boys <9 years), and gonadarche (PG; <9 years) in children with high dehydroepiandrosterone sulphate (DHEAS [HD]) vs those with normal DHEAS (ND).

Setting and Intervention:

Longitudinal Chilean cohort (n = 1052, 49.9% girls). Annual clinical examination including secondary sex characteristics by Tanner staging. Logistic regression models were adjusted by age and BMI.

Main Outcome:

Assess the relationship between DHEAS and premature thelarche, gonadarche, and pubarche in both sexes.

Results:

At age of DHEAS determination, overweight/obesity was present in 44.3% of boys and 42.9% of girls. Incidences of any precocious event were observed in 17.2% of boys and in 25.4% of girls, presented as 8.7% of PG and 8.5% of PP in boys and as 21.3% of PT and 4.1% of PP in girls. In crude and adjusted models in boys, HD did not increase the risk of earlier pubertal events. Conversely, girls with HD had a 2.6 times greater risk of early thelarche and a three times greater risk of early pubarche compared with girls with ND concentrations.

Conclusion:

In Chilean adolescents, precocious events of pubertal development were in line with the worldwide secular trend of earlier sexual maturation. HD was only associated with PT and PP in girls. Continuous follow-up of this cohort is a unique opportunity to prospectively address and analyze the interrelationships among HD, early growth, and adiposity as determinants of gonadarche, pubertal rate/sequence progression, and ovarian function.

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

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

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

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

Leptin as a Predictive Marker in Unexplained Infertility in North Indian Population

INTRODUCTION

According to WHO, the primary infertility in India is about 3.9% (age-standardized to 25-49 year) and 16.8% (age-standardized to 15-49 year), using the "age but no birth" definition. Several factors which affect fertility include low sperm production in men, poor egg quality and blocked fallopian tubes in women and also hormonal imbalances. Leptin plays a critical role in women's reproduction and neuroendocrine health. It is used for treating exercise-induced bone loss, eating disorders and infertility.

AIM

To evaluate the serum leptin levels in Indians and to ascertain the relationship between serum leptin levels, Unexplained Infertility (UI) and related variables [height, weight, Waist Hip Ratio (WHR), Body Mass Index (BMI)] between obese infertile, non-obese infertile and healthy subjects.

MATERIALS AND METHODS

The present case-control study was conducted at the Department of Obstetrics and Gynaecology, King George's Medical University (KGMU), Lucknow, India and funded by Department of Science and Technology, New Delhi, India. The study included 229 female participants in the age group of 18-40 years (120 cases and 109 controls) who were randomly selected. The blood samples were collected from the Infertility Clinic, Queen Mary's Hospital, KGMU, Lucknow, India. All the participants underwent complete physical examination. Initially, the participants were categorized into fertile and infertile groups, they were further divided on the basis of BMI, normal (BMI- 18.5-24.5) and overweight or obese (BMI≥25). Leptin level was measured by Active Human Leptin ELISA kit and BMI of all subjects was calculated in kg/m² (weight in kg and height in m).

RESULTS

A highly positive linear correlation (R=0.754, p<0.001) was found between BMI and serum leptin in unexplained infertile women, which indicates a strong relationship between BMI and serum leptin. The variation in serum leptin is explained by the independent variable, BMI. There was a partial positive linear correlation between BMI and serum leptin in the control group. Statistically there was no significant correlation (R=0.109, p=0.258) between BMI and serum leptin in the control group.

CONCLUSION

The present study clearly demonstrates that level of leptin is higher in unexplained infertile than in the fertile group, and also shows that a strong relationship exists between BMI and serum leptin in the obese group. Serum leptin level was significantly higher in obese than non-obese subjects. Thus, leptin is an important factor for normal reproductive function. Obesity, the main cause of infertility may be controlled by regulating the leptin concentration.

Neuroendocrine-immune circuits, phenotypes, and interactions

Multidirectional interactions among the immune, endocrine, and nervous systems have been demonstrated in humans and non-human animal models for many decades by the biomedical community, but ecological and evolutionary perspectives are lacking. Neuroendocrine-immune interactions can be conceptualized using a series of feedback loops, which culminate into distinct neuroendocrine-immune phenotypes. Behavior can exert profound influences on these phenotypes, which can in turn reciprocally modulate behavior. For example, the behavioral aspects of reproduction, including courtship, aggression, mate selection and parental behaviors can impinge upon neuroendocrine-immune interactions. One classic example is the immunocompetence handicap hypothesis (ICHH), which proposes that steroid hormones act as mediators of traits important for female choice while suppressing the immune system. Reciprocally, neuroendocrine-immune pathways can promote the development of altered behavioral states, such as sickness behavior. Understanding the energetic signals that mediate neuroendocrine-immune crosstalk is an active area of research. Although the field of psychoneuroimmunology (PNI) has begun to explore this crosstalk from a biomedical standpoint, the neuroendocrine-immune-behavior nexus has been relatively underappreciated in comparative species. The field of ecoimmunology, while traditionally emphasizing the study of non-model systems from an ecological evolutionary perspective, often under natural conditions, has focused less on the physiological mechanisms underlying behavioral responses. This review summarizes neuroendocrine-immune interactions using a comparative framework to understand the ecological and evolutionary forces that shape these complex physiological interactions.

Gynecomastia and hormones

Gynecomastia-the enlargement of male breast tissue in men-is a common finding, frequently observed in newborns, adolescents, and old men. Physiological gynecomastia, occurring in almost 25 % of cases, is benign and self-limited; on the other hand, several conditions and drugs may induce proliferation of male breast tissue. True gynecomastia is a common feature often related to estrogen excess and/or androgen deficiency as a consequence of different endocrine disorders. Biochemical evaluation should be performed once physiological or iatrogenic gynecomastia has been ruled out. Non-endocrine illnesses, including liver failure and chronic kidney disease, are another cause of gynecomastia which should be considered. Treating the underlying disease or discontinuing medications might resolve gynecomastia, although the psychosocial burden of this condition might require different and careful consideration.

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.

Leptin Levels in Women With Polycystic Ovary Syndrome: A Systematic Review and a Meta-Analysis

OBJECTIVE

Conflicting results regarding leptin levels in women with polycystic ovary syndrome (PCOS) have been reported. We summarize all available evidence from human participant studies to evaluate leptin levels in PCOS.

DATA SOURCES

PubMed, ClinicalTrials.gov , and Web of Science databases were searched with English-language restriction for only human beings from the inception to December 31, 2015. Search terms included PCOS (polycystic ovary syndrome or PCOS) and leptin.

METHODS OF STUDY SELECTION

A total of 238 studies were reviewed, and a total of 19 studies, involving 991 women with PCOS and 898 controls, were eligible for our meta-analysis. Studies were eligible if provided leptin means and standard deviation in women with PCOS and healthy women controls.

RESULTS

Parameters, such as body mass index, insulin resistance (IR), and total testosterone, which may influence leptin levels were extracted. Data were collected and analyzed by RevMan 5.3 and Stata/SE14.0. The pooling analysis of all relevant studies revealed that leptin levels were significantly higher in patients with PCOS than in controls, with standardized mean difference of 1.62 (95% confidence interval: 1.01-2.23). However, the heterogeneity across studies was considerable and not eliminated in subgroup analyses. Meta-regression analysis further suggested that the heterogeneity might be relevant to variability in IR and study location.

CONCLUSION

Elevated leptin levels are detected in women with PCOS compared with non-PCOS controls. Higher leptin levels may be correlated with IR, metabolic disorder, infertility, and even cardiovascular disease risk in PCOS, which may contribute to the etiology and development of PCOS.