Association of ghrelin and leptin with reproductive hormones in constitutional delay of growth and puberty

Unraveling the impact of hyperleptinemia on female reproduction: insights from transgenic pig model

BACKGROUND

Infertility is a growing global health concern affecting millions of couples worldwide. Among several factors, an extreme body weight adversely affects reproductive functions. Leptin is a well-known adipokine that serves as an endocrine signal between adiposity and fertility. However, the exact mechanisms underlying the effects of high leptin level on female reproduction remain unclear.

METHODS

Transgenic pigs overexpressing leptin (♀) were produced by backcrossing and screened for leptin overexpression. The growth curve, fat deposition, reproductive performance, apoptosis, serum hormones and cholesterol production, RNA sequencing, and single-nucleus RNA sequencing (snRNA-seq) of the leptin-overexpressing pigs and wild-type group were evaluated.

RESULTS

Transgenic pigs overexpressing leptin (♀) were obtained, which exhibited significantly reduced body weight, body size, and back fat thickness. These pigs manifested a late onset of puberty (330 ± 54.3 vs. 155 ± 14.7 days), irregular estrous behavior characterized by increased inter-estrous interval (29.2 ± 0 vs. 21.3 ± 0.7 days), and more number of matings until pregnancy (at least 3 times). This reproductive impairment in leptin pigs was related to hormonal imbalances characterized by increased levels of FSH, LH, prolactin, E2, P4, and TSH, altered steroidogenesis such as increased levels of serum cholesterol esters along with steroidogenic markers (StAR, CYP19A), and ovarian dysfunctions manifested by neutrophilic infiltration and low expression of caspase-3 positive cells in the ovaries. Moreover, bulk RNA sequencing of the ovaries also revealed neutrophilic infiltration followed by upregulation of inflammation-related genes. Furthermore, snRNA-seq reflected that leptin overexpression triggered immune response, suppressed follicle development and luteinization, resulting in metabolic dysfunction and hormone imbalance in the ovary.

CONCLUSIONS

Low body weight in leptin overexpressing pigs adversely affects the reproductive performance, causing delayed puberty, irregular estrous cycles, and reduced breeding efficiency. This is linked to metabolic imbalances, an increased immune response, and altered ovarian functions. This study provides a theoretical basis for the complex mechanisms underlying leptin, and infertility by employing leptin-overexpressing female pigs.

Precocious Puberty Diagnoses Spike, COVID-19 Pandemic, and Body Mass Index: Findings From a 4-year Study

Context

Since the COVID-19 outbreak, the number of girls with suspected precocious puberty has increased.

Objective

To compare the incidence of idiopathic central precocious puberty (ICPP) during COVID-19 with that of the previous 4 years.

Methods

Anthropometric, biochemical, and radiological parameters were collected between January 2016 and June 2021 from 133 girls who met the Rapidly Progressive ICPP criteria (RP-ICPP).

Results

We found a higher incidence of RP-ICPP between March 2020 and June 2021 (group 2) compared with January 2016 through March 2020 (group 1) (53.5% vs 41.1%); 2021 showed the highest annual incidence (P < .05). Group 1 and group 2 differed in age at diagnosis (7.96 ± 0.71 vs 7.61 ± 0.94; P < .05), mean Tanner stage (2.86 ± 0.51 vs 2.64 ± 0; P < .05), and in the time between the appearance of thelarche and diagnosis (0.93 ± 0.75 vs 0.71 ± 0.62 years, P < .05). There was an increase in the number of girls aged <8 years in group 2 and a significantly higher number of girls aged >8 years was found in group 1 (42 in group 1 vs 20 in group 2, P < 0.05). Overall body mass index SD score showed higher values ​​in group 2 (1.01 ± 1.23 vs 0.69 ± 1.15; P = .18), which spent an average of 1.94 ± 1.81 hours per day using electronic devices; 88.5% of this group stopped any physical activity.

Conclusions

A spike in new diagnoses of idiopathic (1.79-fold higher) and RP-CPP coincided with the COVID-19 pandemic. The incidence of RP-ICPP was 1.3-fold higher during COVID-19 with a trend toward an increase in body mass index SD score. The expanding use of digital devices and the reduction of daily physical activity represent possible risk factors.

Is blue light exposure a cause of precocious puberty in male rats?

Purpose

Our study aimed to examine the effects of blue light exposure on prepubertal male rats' puberty and testis tissue.

Methods

Eighteen 21-day-old male Sprague Dawley rats were divided into three groups consisting of six rats in each group: Control Group (CG), Blue Light-6 hours (BL-6), and Blue Light-12 hours (BL-12). CG rats were maintained with 12/12-hour light-dark cycles. The rats of BL-6 and BL-12 were exposed to blue light (450-470nm/irradiance level 0.03uW/cm2) for 6 hours and 12 hours, respectively. Rats were exposed to blue light until the first signs of puberty. The ELISA method was used to analyze the serum levels of FSH, LH, testosterone, DHEA-S, leptin, ghrelin, melatonin, glutathione, glutathione peroxidase, and malondialdehyde. Testes were dissected for histomorphological examination.

Results

The medians of the pubertal entry days of the CG, BL-6, and BL-12 were 38^th, 30^th, and 28^th days, respectively. (p:0.001) The FSH, LH, and testosterone concentrations of all groups were similar. The FSH concentration increased as the LH concentration increased (r: 0.82 p: 0.001). The serum LH concentration increased as serum testosterone, and DHEAS decreased, respectively (r: -0.561, p: 0.01) (r:-0.55 p:0.01). Testicular lengths and weights of the BL groups were smaller compared to CG (p: 0.03),(p: 0.04). GPx was higher for BL-6 and BL-12 than the CG (p:0.021, p:0.024). Testis tissue was compatible with the pubertal period in all groups. As the blue light exposure time increased, spermatogenesis was suppressed, and capillary dilatation and edema in the testis tissue increased.

Conclusion

Our study is the first to show the effects of blue light exposure on male rats' puberty process. And we showed that exposure to blue light and the duration of exposure lead to precocious puberty in male rats. The blue light exposure suppressed spermatogenesis, marked vasodilatation in the interstitial area of the testis, and disrupted the integrity of the basement membrane. These findings intensified with increasing exposure time.

Leptin, ghrelin, nesfatin-1, and orexin-A plasma levels in girls with premature thelarche

PURPOSE

Reducing the mean age of puberty onset in recent years has crucial public health, clinical, and social implications. This study aimed to evaluate the serum levels of appetite-related peptides (leptin, ghrelin, nesfatin-1, and orexin-A) and anthropometric data in girls with premature thelarche (PT).

METHODS

We enrolled 44 girls aged 4-8 years diagnosed with PT and 33 age-matched healthy girls as controls. The demographic data of the girls were obtained using a questionnaire. Anthropometric data were measured and fasting blood samples were collected.

RESULTS

Body weight, height, body mass index (BMI), body fat mass, and basal metabolic rate (BMR) were higher in the PT group than in the control group (p < 0.05). Serum leptin (p < 0.001), nesfatin-1 (p = 0.001), and orxein-A (p < 0.001) levels were significantly higher in the PT group than in healthy controls. However, there were no significant differences in the serum ghrelin levels between the groups (p > 0.05). The results of multivariate logistic regression revealed that serum leptin level (OR (95% CI): 42.0 (10.91, 173.06), p < 0.001), orexin-A (OR (95% CI): 1.14 (1.04, 1.24), p = 0.006), and BMI for age z-score (OR (95% CI): 6.97 (1.47, 33.4), p = 0.014) elevated the risk of incidence of PT at 4-8 girls.

CONCLUSION

These results suggest that in addition to serum leptin levels, serum orexin-A and nesaftin-1 can take part in the initiation of PT. Few studies have investigated the relationship between nesfatin-1 and orexin-A levels and age at onset of puberty; hence, it should be a subject for future studies.

Correlation of body mass index to Ghrelin and IGF-1 among children with short stature

OBJECTIVE

To assess the BMI among children with Growth Hormone Deficiency (GHD) and Idiopathic Short Stature (ISS) and its correlation to ghrelin, Growth Hormone (GH), and Insulin-like Growth Factor-1 (IGF-1) levels.

METHODS

A cross-sectional descriptive study in which 42 patients attending the Pediatric endocrine clinic were enrolled, allocated into two groups: group I: GHD children; group II: ISS children. Ghrelin, IGF-1 and GH in both groups were measured.

RESULTS

Ghrelin was significantly higher among GHD group (p < 0.001). Overall, there was a strong negative correlation between IGF-1 and ghrelin (r = -0.977, p-value = < 0.001) while a moderate positive correlation between ghrelin and BMI (r = 0.419, p-value = 0.006). There was a weak positive non-significant correlation between IGF-1 and BMI (r = 0.276, p-value = 0.077). In GHD group, there was a weak positive non-significant correlation between ghrelin and GH_max measurement (r = 0.052, p-value = 0.824), while a weak negative non-significant correlation between both variables in ISS group (r = -0.243, p-value = 0.288). In GHD group, there was a moderate positive correlation between ghrelin and BMI (r = 0.500, p-value = 0.021), but weak negative non-significant correlation between both variables in ISS group (r = -0.255, p-value = 0.265).

CONCLUSION

There was a negative feedback loop between ghrelin and IGF-1, whereas a positive feedback between ghrelin and BMI. BMI was more affected in the ISS group but was non-significantly correlated with ghrelin. There was no significant compensatory response of ghrelin suggesting its contribution to the pathogenesis of ISS.

Gonadal function in Noonan syndrome

Noonan syndrome (NS) is a relatively common developmental disorder characterised by the association of craniofacial abnormalities, congenital heart defects, short stature and skeletal abnormalities, variable developmental delay/learning disability, and predisposition to certain cancers. NS is caused by germline mutations in genes encoding components or regulators of the RAS/mitogen-activated protein kinase (MAPK) signaling pathway. Although abnormalities in the hypothalamic-pituitary-gonadal axis have long been reported in NS patients, there is only scarce published data on this subject. Puberty is usually delayed of about two years for both boys and girls with NS. However, in the majority of patients, it starts spontaneously suggesting a normal hypothalamic-pituitary input. The lower fat mass usually observed in NS patients may influence the timing of puberty. Although there is almost no reliable data on this issue, it is usually considered that fertility is not affected in NS females. In contrast, primary testicular insufficiency, predominant on Sertoli cell function, is reported in NS males. However, the exact frequency of infertility in adult males is unknown. More generally, although the features of NS are well described during childhood, little is known about the progression of the disease in adulthood. Prospective long-term follow-up studies are required to further investigate gonadal function and fertility in NS adults and to clarify the long-term follow-up of these patients.

Differences in Puberty of Girls before and during the COVID-19 Pandemic

In the COVID-19 pandemic, there was an increase in consultations for precocious puberty. We aim to analyze differences in female puberty before and during the COVID-19 pandemic. A cross-sectional analytical study was designed at the Pediatric Endocrinology Clinic of the University Hospital of the Federal University of Maranhão in São Luis, Brazil. We included 55 girls with precocious puberty, 22 who started puberty during the pandemic and 33 who started puberty before the pandemic. Clinical, anthropometric, laboratory and imaging variables were compared between groups. Statistics were performed to determine if there was a statistical difference between the groups. Girls with puberty during the pandemic had higher Z-scores for weight (1.08 ± 1.29 versus 0.69 ± 0.83; p = 0.04), lower ovarian volume (1.88 ± 0.95 versus 3.15 ± 2.31; p = 0.01), and smaller differences between thelarche noticed by the parents and the diagnosis (6.63 ± 5.21 versus 12.15 ± 9.96; p = 0.02). The association between precocious puberty during the pandemic with higher Z-scores for weight, lower ovarian volume, and a reduction in the time between the perception of pubertal findings by parents and the diagnosis suggests the influence of the pandemic on the normal time of puberty.

"Sibling" battle or harmony: crosstalk between nesfatin-1 and ghrelin

Ghrelin was first identified as an endogenous ligand of the growth hormone secretagogue receptor (GHSR) in 1999, with the function of stimulating the release of growth hormone (GH), while nesfatin-1 was identified in 2006. Both peptides are secreted by the same kind of endocrine cells, X/A-like cells in the stomach. Compared with ghrelin, nesfatin-1 exerts opposite effects on energy metabolism, glucose metabolism, gastrointestinal functions and regulation of blood pressure, but exerts similar effects on anti-inflammation and neuroprotection. Up to now, nesfatin-1 remains as an orphan ligand because its receptor has not been identified. Several studies have shown the effects of nesfatin-1 are dependent on the receptor of ghrelin. We herein compare the effects of nesfatin-1 and ghrelin in several aspects and explore the possibility of their interactions.

Difference of Precocious Puberty Between Before and During the COVID-19 Pandemic: A Cross-Sectional Study Among Shanghai School-Aged Girls

OBJECTIVE

To compared the incidence rates and clinical features of precocious girls before and during the COVID-19 pandemic among Shanghai school-aged girls, and explored the potential mechanisms.

METHODS

This cross-sectional study collected medical data about precocious girls between 2016 and 2020 from Shanghai Children's Medical Center. Data of inpatient precocious girls from March to August in 2016-2019 (n=246) and 2020 (n=237) were collected. Subjects with abnormal brain and pituitary gland MRI reports, other endocrine diseases or chronic diseases were excluded. Finally, 209 precocious girls were included in the 2016-2019 group and 191 precocious girls were include in the 2020 group. Monthly incidence rates and clinical features were compared between before and during the COVID-19 pandemic. Linear regression models were used to examine the associations between biomarkers to explore the potential mechanisms.

RESULTS

Monthly incidence rates of precocious puberty in outpatient girls from March to December 2020 (0.44-1.36%) and in inpatient girls from March to August 2020 (27.04-47.83%) were higher than those in 2016-2019 (0.30-0.52% and 10.53-18.42%, respectively). Serum concentrations of GnRH were higher in the 2020 group than in the 2016-2019 group (2.81 vs 1.99 mg/L). Serum concentrations of MKRN3 (1.02 vs 1.93 ng/ml) and ghrelin (0.38 vs 0.88 ng/ml) were lower in the 2020 group than in the 2016-2019 group. Moreover, the serum concentration of ghrelin was positively associated with the serum concentration of MKRN3 [β=0.891 (95% CI, 0.612, 1.171); p<0.001].

CONCLUSIONS

These findings suggest an increased incidence of precocious puberty during the COVID-19 pandemic among Shanghai school-aged girls, which may be associated with decreased serum concentrations of MKRN3 and ghrelin, and indicated ghrelin as a potential regulatory mechanism of puberty.

Delayed body development with reduced triglycerides levels in leptin transgenic pigs

Leptin is a well-known adipokine that plays critical role in adiposity. To further investigate the role of leptin in adiposity, we utilized leptin overexpressing transgenic pigs and evaluated the effect of leptin on growth and development, fat deposition, and lipid metabolism at tissue and cell level. Leptin transgenic pigs were produced and divided into two groups: elevated leptin expression (leptin ( +)) and normal leptin expression group (control). Results indicated that leptin ( +) pigs had elevated leptin protein and mRNA expression levels and exhibited sluggish growth and development followed by decreased subcutaneous fat thickness, low serum triglycerides, saturated, unsaturated fatty acids and high cholesterol esters (p < 0.05). There were differences in the lipid metabolism related genes at different fat depots, including upregulation of PPARγ, AGPAT6, PLIN2, HSL and ATGL in subcutaneous, PPARγ in perirenal, and FAT/CD36 and PLIN2 in mesenteric adipose tissues and downregulation of AGPAT6 and ATGL in perirenal and AGPAT6 in mesenteric adipose tissues (p < 0.05). Additionally, in-vitro cultured leptin ( +) preadipocytes exhibited upregulation of PPARγ, FAT/CD36, ACACA, AGPAT, PLIN2, ATGL and HSL as compared to control (p < 0.05). These findings suggested that homeostasis imbalance in lipolysis and lipogenesis at adipose tissue and adipocytes levels led to low subcutaneous fat depots in leptin overexpression pigs. These pigs can act as model for obesity and related metabolic disorder.

A potential role for the adrenal gland in autism

Androgens have been implicated in autism pathophysiology as recently, prenatal exposure to elevated androgens has been proposed as risk factor. However, published data on postnatal sex hormone levels in autistic children are controversial and the source of prenatal androgen exposure in autism remains unknown. Therefore, this study investigated postnatal sex hormone levels and dehydroepiandrosterone (DHEA) to shed light on a potential role for the adrenal gland in autism pathophysiology. A case-control study investigating estradiol (E2), DHEA, follicle-stimulating hormone (FSH) and luteinizing hormone (LH) levels was conducted with 31 Saudi males with autism and 28 healthy, age-matched boys plasma. Moreover, correlation analysis with measured hormones and previously measured total testosterone (TT) and free testosterone (FT) in the same group of autism was conducted. DHEA was significantly higher (p < 0.05) in the autism group compared to controls. DHEA positively correlated with previously measured TT (r = + 0.79, p < 0.001) and FT (r = + 0.72, p < 0.001) levels in the same autism group. FSH levels were also significantly higher in the autism group than in the control group (p < 0.01). To the best of our knowledge, this is the first study to report a strong positive correlation between TT, FT and DHEA, suggesting an adrenal source for elevated androgen levels.

Obesity in childhood: how to improve male adolescence incoming

INTRODUCTION

Earlier or delayed puberty can be determined by numerous causes, but the exact mechanisms are not fully known. Anyway, those may be independent from the hypothalamicpituitary-gonadal axis involvement. Certainly, obesity is one of the main factors. In fact, obesity and infertility are strongly linked. For this reason, we want to analyse the relationship between puberty and obesity and give an updated state-of-the-art starting by discussing a 14-year-old obese boy's clinical case.

EVIDENCE ACQUISITION

Literature data are conflicting. Main criticisms are related to study design and evaluation criteria. Indeed, examined populations are not homogeneous by age, Tanner stage and BMI classification. The obesity epidemic is involved in earlier puberty, and puberty seems to be anticipated in all BMI groups. Very few studies evaluate the level of adiposity in the diagnosis of obesity. However, the role of the adipose tissue is crucial for hormone synthesis and regulation. Therefore, fat mass age-related and not simply BMI has to be considered by clinicians for appropriate diagnosis.

EVIDENCE SYNTHESIS

Regarding the clinical case, in three months our patient recovered delayed pubertal development following an anti-inflammatory and antioxidant Mediterranean Diet. Loss of weight, as in decrease of fat mass but saving of lean mass, increased testicular volume and testosterone levels occurred.

CONCLUSIONS

Puberty depends on several factors, including obesity. Further studies are needed to evaluate age groups, Tanner stage, diet and lifestyle, ethnicity and above all the fat/lean mass ratio. Lack of adequate tools could hinder a clinician's ability to recognize when or if therapeutic intervention is needed.

ESR1 gene polymorphism (rs827421) as a potential genetic marker for constitutional delay of growth and puberty in Egyptian adolescents

Constitutional delay of growth and puberty (CDGP) is a variant of normal pubertal timing and progress. It is the most common form of delayed puberty in both genders. The genetic director of CDGP is ill-understood despite the positive family history result noted in those patients. The current study aimed at assessing the role of estrogen receptor 1 (ESR1) gene variant (rs827421) in Egyptian adolescents with CDGP. A cross-sectional study with follow-up part was carried out on 6760 children aged 4 to15 years. The study focused generally on children aged 13-15 years in order to evaluate the prevalence of delayed puberty in relation to all ages in general and to their peers in specific. Assessment of serum TSH, FSH, and LH was conducted on all participants, along with the measurement of serum-free testosterone for males and estradiol for females. Genotyping of ESR1 (rs827421) was done to all subjects through the use of TaqMan discrimination assay by real-time PCR. ESR1 (rs827421) GG genotype and G allele were significantly dominant among CDGP adolescents in comparison with controls (OR = 25.67 and 6.90). As regards follow-up of testicular size, AA genotype was significantly associated with increased size in the right and left testis compared to other genotypes (P = 0.021 and 0.006, respectively). Moreover, AA genotype showed significantly higher Tanner stage in both males and females in comparison with other genotypes. Serum estradiol level was significantly higher in AA genotype group than other genotypes groups. ESR1 gene polymorphism can be considered a potential genetic marker for CDGP in both sexes in a sample of Egyptian adolescents.

Ghrelin as an anti-inflammatory and protective agent in ischemia/reperfusion injury

Ischemia/reperfusion (I/R) continue to be the most frequent cause of damaged tissues. Injured tissues resulted from the first ischemic insult, which is determined by the interruption in the blood supply, followed by subsequent impairment induced by reperfusion. In addition, ischemia-reperfusion injury is mediated by tumor necrosis factor (TNF) and other cytokines that activate complements and proteases responsible for free radical production. However, earlier studies have reported the protective roles of bioactive peptides during ischemia reperfusion injury. In fact, ghrelin is a peptide hormone discovered since 1999 as GH secretagogue and its production was identified in gastric X/A-like endocrine cells in rats and P/D1 type cells in humans. To date, this peptide receives growing attention due to its pleiotropic action in the organism and its role in maintaining energy homeostasis. Ghrelin is also involved in stress responses, assuming a modulatory action on immune pathways. Previous studies have identified many other functions related to an anti-inflammatory role in ischemia reperfusion injury. Under these challenging conditions, studies described acylated and unacylated ghrelin in activation and/or inhibition processes related to ischemia-reperfusion injury. The aim of this article is to provide a minireview about ghrelin mechanisms involved in the proinflammatory response of I/R injury. However, the regulatory processes of ghrelin in this pathologic event are still very limited and warrant further investigation.

Noonan syndrome males display Sertoli cell-specific primary testicular insufficiency

Context Abnormalities in the hypothalamo-pituitary-gonadal axis have long been reported in Noonan syndrome (NS) males with only few data available in prepubertal children. Objective The aim of this study was to describe the gonadal function of NS males from childhood to adulthood. Design It is a retrospective chart review. Patients and methods A total of 37 males with a genetically confirmed diagnosis of NS were included. Clinical and genetic features, as well as serum hormone levels (LH, FSH, testosterone, anti-Müllerian hormone (AMH), and inhibin B) were analysed. Results Of the 37 patients, 16 (43%) children had entered puberty at a median age of 13.5 years (range: 11.4-15.0 years); age at pubertal onset was negatively correlated with BMI SDS (r = -0.541; P = 0.022). In pubertal boys, testosterone levels were normal suggesting a normal Leydig cell function. In contrast, NS patients had significant lower levels of AMH (mean SDS: -0.6 ± 1.1; P = 0.003) and inhibin B (mean SDS: -1.1 ± 1.2; P < 0.001) compared with the general population, suggesting a Sertoli cell dysfunction. Lower AMH and inhibin B levels were found in NS-PTPN11 patients, whereas these markers did not differ from healthy children in SOS1 patients. No difference was found between cryptorchid and non-cryptorchid patients for AMH and inhibin B levels (P = 0.43 and 0.62 respectively). Four NS-PTPN11 patients had a severe primary hypogonadism with azoospermia/cryptozoospermia. Conclusions NS males display Sertoli cell-specific primary testicular insufficiency, whereas Leydig cell function seems to be unaffected.

Hormonal and nutritional regulation of postnatal hypothalamic development

The hypothalamus is a key centre for regulation of vital physiological functions, such as appetite, stress responsiveness and reproduction. Development of the different hypothalamic nuclei and its major neuronal populations begins prenatally in both altricial and precocial species, with the fine tuning of neuronal connectivity and attainment of adult function established postnatally and maintained throughout adult life. The perinatal period is highly susceptible to environmental insults that, by disrupting critical developmental processes, can set the tone for the establishment of adult functionality. Here, we review the most recent knowledge regarding the major postnatal milestones in the development of metabolic, stress and reproductive hypothalamic circuitries, in the rodent, with a particular focus on perinatal programming of these circuitries by hormonal and nutritional influences. We also review the evidence for the continuous development of the hypothalamus in the adult brain, through changes in neurogenesis, synaptogenesis and epigenetic modifications. This degree of plasticity has encouraging implications for the ability of the hypothalamus to at least partially reverse the effects of perinatal mal-programming.

Review of the role of leptin in the regulation of male reproductive function

Since discovered in 1994, leptin has been thought to be a pleiotropic hormone that regulates food intake, controls energy balance in the body and influences multiple tissues in the body. Leptin plays an important mediating role in the regulation of neuroendocrine and can transmit the nutritional status signals to the reproductive-related central nervous system. Many studies have shown that leptin may play an important role in the control of reproductive function. Leptin can act on all levels of the hypothalamus-pituitary-gonadal (HPG) axis and may have local effects on the function of testis and spermatogenesis. Leptin is critical for puberty initiation and can also modulate testosterone synthesis by downregulating cAMP-dependent activation of steroidogenic genes expressions. Leptin is found to be higher in infertile men than in normal subjects. Yet, the exact role of leptin in the regulation of male reproductive function remains incomplete. The purpose of this review was to summarise the recent research about the biological effects of leptin on male reproductive system. In-depth study of leptin in reproductive system will help to reveal the pathogenesis of infertility and provide new treatment ideas for human assisted reproductive technology.

Linking Stress and Infertility: A Novel Role for Ghrelin

Infertility affects a remarkable one in four couples in developing countries. Psychological stress is a ubiquitous facet of life, and although stress affects us all at some point, prolonged or unmanageable stress may become harmful for some individuals, negatively impacting on their health, including fertility. For instance, women who struggle to conceive are twice as likely to suffer from emotional distress than fertile women. Assisted reproductive technology treatments place an additional physical, emotional, and financial burden of stress, particularly on women, who are often exposed to invasive techniques associated with treatment. Stress-reduction interventions can reduce negative affect and in some cases to improve in vitro fertilization outcomes. Although it has been well-established that stress negatively affects fertility in animal models, human research remains inconsistent due to individual differences and methodological flaws. Attempts to isolate single causal links between stress and infertility have not yet been successful due to their multifaceted etiologies. In this review, we will discuss the current literature in the field of stress-induced reproductive dysfunction based on animal and human models, and introduce a recently unexplored link between stress and infertility, the gut-derived hormone, ghrelin. We also present evidence from recent seminal studies demonstrating that ghrelin has a principal role in the stress response and reward processing, as well as in regulating reproductive function, and that these roles are tightly interlinked. Collectively, these data support the hypothesis that stress may negatively impact upon fertility at least in part by stimulating a dysregulation in ghrelin signaling.

Luteinizing Hormone Secretion during Gonadotropin-Releasing Hormone Stimulation Tests in Obese Girls with Central Precocious Puberty

OBJECTIVE

Girls with precocious puberty have high luteinizing hormone (LH) levels and advanced bone age. Obese children enter puberty at earlier ages than do non-obese children. We analyzed the effects of obesity on LH secretion during gonadotropin-releasing hormone (GnRH) tests in girls with precocious puberty.

METHODS

A total of 981 subjects with idiopathic precocious puberty who had undergone a GnRH stimulation testing between 2008 and 2014 were included in the study. Subjects were divided into three groups based on body mass index (BMI). Auxological data and gonadotropin levels after the GnRH stimulation test were compared.

RESULTS

In Tanner stage 2 girls, peak stimulated LH levels on GnRH test were 11.9±7.5, 10.4±6.4, and 9.1±6.1 IU/L among normal-weight, overweight, and obese subjects, respectively (p=0.035 for all comparisons). In Tanner stage 3 girls, peak stimulated LH levels were 14.9±10.9, 12.8±7.9, and 9.6±6.0 IU/L, respectively (p=0.022 for all comparisons). However, in Tanner stage 4 girls, peak stimulated LH levels were not significantly different among normal, overweight, and obese children. On multivariate analysis, BMI standard deviation score was significantly and negatively associated with peak LH (β=-1.178, p=0.001).

CONCLUSION

In girls with central precocious puberty, increased BMI was associated with slightly lower peak stimulated LH levels at early pubertal stages (Tanner stages 2 and 3). This association was not valid in Tanner stage 4 girls.

Mink aging is associated with a reduction in ovarian hormone release and the response to FSH and ghrelin

The endocrine mechanisms of mink ovarian hormones release and reproductive aging are poorly investigated. The aims of our study were to: (1) identify hormones produced by mink ovaries (the steroids progesterone [P] and estradiol [E], the peptide hormone oxytocin [OT], and the prostaglandin F [PGF] and prostaglandin E [PGE]); (2) examine the effect of FSH and ghrelin on the release of the hormones listed previously; and (3) understand whether these hormones can be involved in the control of mink reproductive aging, i.e., whether aging can be associated with changes (a) in the basal release of P, E, OT, PGF, or PGE and (b) their response to FSH and ghrelin. Fragments of ovaries of young (yearlings) and old (3-5 years of age) minks were cultured with and without FSH and ghrelin (0, 1, 10, or 100 ng/mL), and the release of hormones was analyzed by EIA/RIA. We found that isolated ovaries were able to release P, E, OT, PGF, and PGE, and the levels of P produced in the ovaries of old animals were lower than those produced in the ovaries of young animals, whereas the levels of other hormones did not differ. FSH was able to stimulate P and E and suppress OT and PGF and did not affect PGE release. Aging was associated with the inhibition of the effect of FSH on ovarian P and E, the appearance of the inhibitory action of FSH on OT, and the disappearance of this action on ovarian PGF. PGE was not affected by FSH, irrespective of animal age. Ghrelin was able to promote E (but not P) and suppress OT, PGF, and PGE output. Aging was associated with the appearance of an inhibitory influence of ghrelin on ovarian OT and PGE and with the disappearance of this influence on PGF output. Aging did not affect the action of ghrelin on ovarian P and E. Our observations (1) confirm the production of P and E and show that OT, PGF, and PGE are released from mink ovaries, (2) confirm the involvement of FSH and demonstrate the involvement of ghrelin in the control of mink ovarian hormone release, and (3) suggest that reproductive aging in minks is due to a reduction in basal P release and alterations in the response of E, OT, PGF (but not of PGE) to FSH and ghrelin.

Aging influences steroid hormone release by mink ovaries and their response to leptin and IGF-I

The aim of our study was to understand whether ovarian steroid hormones, and their response to the metabolic hormones leptin and IGF-I leptin, could be involved in the control of mink reproductive aging via changes in basal release of ovarian progesterone and estradiol. For this purpose, we compared the release of progesterone and estradiol by ovarian fragments isolated from young (yearlings) and old (3-5 years of age) minks cultured with and without leptin and IGF-I (0, 1, 10 or 100 ng/ml). We observed that isolated ovaries of older animals produced less progesterone but not less estradiol than the ovaries of young animals. Leptin addition stimulated estradiol release by the ovarian tissue of young animals but inhibited it in older females. Leptin did not influence progesterone output by the ovaries of either young or older animals. IGF-I inhibited estradiol output in young but not old animals, whereas progesterone release was inhibited by IGF-I irrespective of the animal age. Our observations demonstrate the involvement of both leptin and IGF-I in the control of mink ovarian steroid hormones release. Furthermore, our findings suggest that reproductive aging in minks can be due to (a) reduction in basal progesterone release and (b) alterations in the response of estradiol but not of progesterone to leptin and IGF-I.

Summary: Both leptin and IGF-I are involved in the control of mink ovarian steroid hormone release. Reproductive aging can be due to (a) reduction in basal progesterone release and (b) alterations in the response of estradiol but not of progesterone to leptin and IGF-I.

Ghrelin Actions on Somatotropic and Gonadotropic Function in Humans

Ghrelin, a 28 amino-acid octanoylated peptide predominantly produced by the stomach, was discovered to be the natural ligand of the type 1a GH secretagogue receptor (GHS-R1a). It was thus considered as a natural GHS additional to GHRH, although later on ghrelin has mostly been considered a major orexigenic factor. The GH-releasing action of ghrelin takes place both directly on pituitary cells and through modulation of GHRH from the hypothalamus; some functional antisomatostatin action has also been shown. However, ghrelin is much more than a natural GH secretagogue. In fact, it also modulates lactotroph and corticotroph secretion in humans as well as in animals and plays a relevant role in the modulation of the hypothalamic-pituitary-gonadal function. Several studies have indicated that ghrelin plays an inhibitory effect on gonadotropin pulsatility, is involved in the regulation of puberty onset in animals, and may regulate spermatogenesis, follicular development and ovarian cell functions in humans. In this chapter ghrelin actions on the GH/IGF-I and the gonadal axes will be revised. The potential therapeutic role of ghrelin as a treatment of catabolic conditions will also be discussed.

The Changes of Serum Leptin and Kisspeptin Levels in Chinese Children and Adolescents in Different Pubertal Stages

The aim of the study is to investigate the changes of serum leptin and kisspeptin levels in children and adolescents with different pubertal stages and nutritional states. A total of 647 Chinese children and adolescents were recruited, and serum estradiol, testosterone, pituitary gonadotropins, leptin, and kisspeptin levels were measured. The results showed that serum leptin levels of boys in T2 stage were the highest among the five stages, while they showed a gradual increase from T1 to T5 stage in girls and reached the highest in T5 stage (P < 0.05). Conversely, serum kisspeptin levels of boys were higher in T4 and T5 stages than those in T1 stage, while its levels of girls were the highest in T2 stage, 21.4% higher than those in T1 stage (P < 0.05). Both leptin and kisspeptin levels were positively correlated with BMI, WC, and weight in all boys and girls (all P < 0.05). In conclusion, kisspeptin levels were firstly found to be notably changed in pubertal stages and nutritional status in Chinese children and adolescents with a significant sexual dimorphism. Obese/overweight girls had higher kisspeptin levels, and there was a positive correlation between kisspeptin and FSH and LH and obesity-related parameters in all boys and girls.

Elevated phthalates' exposure in children with constitutional delay of growth and puberty

BACKGROUND

Phthalates have been proven to be antiandrogenic, which may interfere with the timing of puberty. Children with Constitutional Delay of Growth and Puberty (CDGP) typically display short stature and pubertal delay. This study investigated whether phthalate's exposure was associated with CDGP, and evaluated the potential mediator role of testosterone.

METHODS

In this case-control study, a total of 167 boys, including 57 boys with CDGP (cases) and 110 controls were enrolled. We measured six major phthalate metabolites in urine samples using high-performance liquid chromatography and tandem mass spectrometry (LC-MS/MS). The serum testosterone level was determined by radioimmunoassay.

RESULTS

Children in the CDGP group were determined to have significantly elevated urinary phthalates concentration compared with control subjects (total phthalates median: case, 107.00 ng/ml; control, 62.22 ng/ml, p = 0.001). After adjustment for BMI and other confounding factors: mono-n-butyl phthalate (MBP), monoethyl phthalate (MEP) and total phthalate concentrations were significantly negatively associated with serum testosterone level (MBP: β = -45.7, p = 0.017; MEP: β = -31.6, p = 0.022; total phthalates: β = -24.6, p = 0.011); MBP, MEP, mono (2-ethylhexyl) phthalate (MEHP) and total phthalates were significantly associated with CDGP (odds ratio: MBP: 8.30, p = 0.002; MEP: 5.43, p = 0.002; MEHP: 3.83, p = 0.017; total phthalates: 9.09, p = 0.001). Serum testosterone level acted as a mediator of the association between phthalates' exposure and CDGP (p = 0.002) (proportion mediated: 34.4%).

CONCLUSIONS

In this case-control study, elevated phthalates' level was detected in children with CDGP in Shanghai, China and phthalate level was associated with CDGP, which appeared to be mediated by circulating testosterone level.

The gonadal function in obese adolescents: review

This review deals with the relationship between obesity in male adolescents and gonadal function. The article is structured in two main paragraphs; the first one is about population studies that have assessed puberty timing and its mode of onset in relation with body weight to evaluate if and how the latter can influence the gonadal function in this phase of life. These studies analyze issues such as increased BMI and early onset of male puberty, gender differences, secular trend toward early onset of puberty in males, effects of a different body composition on male puberty and consequences of a different stage of childhood obesity on the onset of male puberty. The second paragraph examines the possible mechanisms through which, obesity may alter the timing of puberty in young males, including the role of SHBG, leptin, insulin resistance, ghrelin, GH-IGF-1 axis, AR polymorphisms, primary testicular dysfunction, retinol binding protein 4 (RBP-4) and liver function abnormalities. However, despite the numerous studies in the literature, the etiology of gonadal disfunction in obese adolescents on puberty remains uncertain.

Metabolic influences on neuroendocrine regulation of reproduction

PURPOSE OF REVIEW

Reproduction is a tightly regulated function in which many mechanisms contribute to ensure the survival of the species. Among those, due to the elevated energy requirements of reproduction, metabolic factors exert a pivotal role in the control of hypothalamic-pituitary-gonadal axis. Although this control may occur at multiple levels of the axis, the majority of interactions between metabolic and reproductive systems take place in the hypothalamus. In this article, we present an overview of the state-of-the-art knowledge regarding the metabolic regulation of reproduction at the central level. We aim to identify the neuroanatomical location where both functions interconnect by discussing the likelihood of each component of the neuronal hierarchical network controlling gonadotropin-releasing hormone (GnRH) release to be first-order responders to metabolic cues, especially the peripheral metabolic signals leptin, insulin, and ghrelin.

RECENT FINDINGS

Latest evidence suggests that the primary action of leptin, insulin, and ghrelin to regulate reproduction is located upstream of the main central elicitors of gonadotropin release, Kiss1 and GnRH neurons, and neuroanatomically separated from their metabolic action.

SUMMARY

The study of the neuronal interactions between the mechanisms governing metabolism and reproduction offers the platform to overcome or treat a number of prevailing metabolic and/or reproductive conditions.

Diet, physical exercise and Orlistat administration increase serum anti-Müllerian hormone (AMH) levels in women with polycystic ovary syndrome (PCOS)

The present study investigates the combined effect of diet, physical exercise and Orlistat for 24 weeks, on serum anti-Müllerian hormone (AMH) levels in overweight and obese women with polycystic ovary syndrome (PCOS) and in overweight and obese controls. Sixty-one (61) selected women with PCOS and 20 overweight and obese controls followed an energy-restricted diet, physical exercise plus Orlistat administration (120 mg, 3 times per day) for 24 weeks. At baseline, week 12 and week 24, serum levels of AMH, FSH, LH, PRL, androgens, sex hormone-binding globulin (SHBG), glucose, and insulin were measured and Free Androgen Index (FAI) and Insulin Resistance (IR) indices were calculated. In PCOS women, serum AMH levels increased after 12 and 24 weeks of treatment. After 12 weeks LH and SHBG were increased, while Testosterone decreased. After 12 and 24 weeks, FAI was decreased and all indices of IR were significantly improved. We concluded that in overweight and obese women with PCOS Orlistat administration, combined with diet and physical exercise, for 24 weeks, resulted in significant weight loss, improvement of hyperandrogenism and insulin sensitivity, and increased serum AMH levels.

Ghrelin and leptin modulate the feeding behaviour of the hawksbill turtle Eretmochelys imbricata during nesting season

Female sea turtles have rarely been observed foraging during the nesting season. This suggests that prior to their migration to nesting beaches the females must store sufficient energy and nutrients at their foraging grounds and must be physiologically capable of undergoing months without feeding. Leptin (an appetite-suppressing protein) and ghrelin (a hunger-stimulating peptide) affect body weight by influencing energy intake in all vertebrates. We investigated the levels of these hormones and other physiological and nutritional parameters in nesting hawksbill sea turtles in Rio Grande do Norte State, Brazil, by collecting consecutive blood samples from 41 turtles during the 2010-2011 and 2011-2012 reproductive seasons. We found that levels of serum leptin decreased over the nesting season, which potentially relaxed suppression of food intake and stimulated females to begin foraging either during or after the post-nesting migration. Concurrently, we recorded an increasing trend in ghrelin, which may have stimulated food intake towards the end of the nesting season. Both findings are consistent with the prediction that post-nesting females will begin to forage, either during or immediately after their post-nesting migration. We observed no seasonal trend for other physiological parameters (values of packed cell volume and serum levels of alanine aminotransferase, aspartate aminotransferase, alkaline phosphatase, γ-glutamyl transferase, low-density lipoprotein, and high-density lipoprotein). The observed downward trends in general serum biochemistry levels were probably due to the physiological challenge of vitellogenesis and nesting in addition to limited energy resources and probable fasting.

Leptin levels in children and adults with classic galactosaemia

Among the long-term complications of Classic Galactosaemia (Gal) is premature ovarian insufficiency (POI) in female patients with subtle abnormalities of reproductive function also reported in male patients. Leptin is a circulating hormone which reflects body energy stores and which affects the neuroendocrine reproductive axis and pubertal development.We measured serum leptin in 28 children (10 girls, 18 boys; mean age 7.6 years, range 0.5-17.9 years) and in 22 adults (10 females, 12 males; mean age 23.9 years, range 18-37 years) with Gal on a strict galactose-restricted diet in comparison with control data.Leptin levels (expressed as SDS for gender and pubertal stage) were lower in Gal children than controls (mean leptin-SDS = -0.71 for girls, p < 0.05, -0.97 for boys compared with SDS = 0 for controls, p < 0.05). In an age-related analysis, leptin levels did not correlate with age in children with Gal for both sexes as it did for matched controls.As expected, females had higher leptin levels than males in either group. In adults with Gal, leptin concentrations were within normal limits for both sexes when adjusted for gender and BMI. There was a linear relationship between log-leptin and BMI in children with Gal and in controls. For Gal women, log-leptin was also associated with BMI. However, for Gal men, and hence for the entire group of adult Gal patients, this association between log-leptin and BMI was not detectable. Our findings suggest that leptin dysregulation may play a role in fertility issues in individuals with Gal from an early age.

Leptin signaling and circuits in puberty and fertility

Leptin is an adipocyte-derived hormone involved in a myriad of physiological process, including the control of energy balance and several neuroendocrine axes. Leptin-deficient mice and humans are obese, diabetic, and display a series of neuroendocrine and autonomic abnormalities. These individuals are infertile due to a lack of appropriate pubertal development and inadequate synthesis and secretion of gonadotropins and gonadal steroids. Leptin receptors are expressed in many organs and tissues, including those related to the control of reproductive physiology (e.g., the hypothalamus, pituitary gland, and gonads). In the last decade, it has become clear that leptin receptors located in the brain are major players in most leptin actions, including reproduction. Moreover, the recent development of molecular techniques for brain mapping and the use of genetically modified mouse models have generated crucial new findings for understanding leptin physiology and the metabolic influences on reproductive health. In the present review, we will highlight the new advances in the field, discuss the apparent contradictions, and underline the relevance of this complex physiological system to human health. We will focus our review on the hypothalamic circuitry and potential signaling pathways relevant to leptin’s effects in reproductive control, which have been identified with the use of cutting-edge technologies of molecular mapping and conditional knockouts.