Incretins modulate progesterone biosynthesis by regulating bone morphogenetic protein activity in rat granulosa cells

Mechanisms of probiotic modulation of ovarian sex hormone production and metabolism: a review

Sex hormones play a pivotal role in the growth and development of the skeletal, neurological, and reproductive systems. In women, the dysregulation of sex hormones can result in various health complications such as acne, hirsutism, and irregular menstruation. One of the most prevalent diseases associated with excess androgens is polycystic ovary syndrome with a hyperandrogenic phenotype. Probiotics have shown the potential to enhance the secretion of ovarian sex hormones. However, the underlying mechanism of action remains unclear. Furthermore, comprehensive reviews detailing how probiotics modulate ovarian sex hormones are scarce. This review seeks to shed light on the potential mechanisms through which probiotics influence the production of ovarian sex hormones. The role of probiotics across various biological axes, including the gut-ovarian, gut-brain-ovarian, gut-liver-ovarian, gut-pancreas-ovarian, and gut-fat-ovarian axes, with a focus on the direct impact of probiotics on the ovaries via the gut and their effects on brain gonadotropins is discussed. It is also proposed herein that probiotics can significantly influence the onset, progression, and complications of ovarian sex hormone abnormalities. In addition, this review provides a theoretical basis for the therapeutic application of probiotics in managing sex hormone-related health conditions.

Metabolic hormones are integral regulators of female reproductive health and function

The female reproductive system is strongly influenced by nutrition and energy balance. It is well known that food restriction or energy depletion can induce suppression of reproductive processes, while overnutrition is associated with reproductive dysfunction. However, the intricate mechanisms through which nutritional inputs and metabolic health are integrated into the coordination of reproduction are still being defined. In this review, we describe evidence for essential contributions by hormones that are responsive to food intake or fuel stores. Key metabolic hormones-including insulin, the incretins (glucose-dependent insulinotropic polypeptide and glucagon-like peptide-1), growth hormone, ghrelin, leptin, and adiponectin-signal throughout the hypothalamic-pituitary-gonadal axis to support or suppress reproduction. We synthesize current knowledge on how these multifaceted hormones interact with the brain, pituitary, and ovaries to regulate functioning of the female reproductive system, incorporating in vitro and in vivo data from animal models and humans. Metabolic hormones are involved in orchestrating reproductive processes in healthy states, but some also play a significant role in the pathophysiology or treatment strategies of female reproductive disorders. Further understanding of the complex interrelationships between metabolic health and female reproductive function has important implications for improving women's health overall.

Disturbed ovarian morphology, oestrous cycling and fertility of high fat fed rats are linked to alterations of incretin receptor expression

Obesity is a major cause of infertility in females with a direct correlation between energy intake and reproductive dysfunction. To explore underlying mechanisms, disturbances in reproductive health and incretin/reproductive hormone receptor expression were studied in female Wistar rats fed a high-fat-diet for 20-weeks. Metabolic parameters and ovarian/adrenal gene expression were monitored along with estrous cycling and fertility upon mating. High-fat-feeding significantly increased body weight, plasma insulin and HOMA-IR, indicative of obesity and insulin resistance. Estrous cycles were prolonged compared to normal chow-fed rats, with 50 % having an average cycle length ≥ 7days. Reproductive outcomes revealed high-fat-diet reduced litter size by 48 %, with 16 % rats unable to achieve pregnancy. Furthermore, 80 % of the high-fat group took > 35 days to become pregnant compared to 33 % fed a normal-diet. Also, 35 % of pups born to high-fat-fed rats were eaten by mothers or born dead which was not observed with control rats. These changes were associated with downregulation of Amh, Npy2R and GcgR gene expression in ovaries with upregulation of InsR and Glp-1R genes. In adrenals, Glp-1R, GipR, Npy2R, InsR, GcgR, GshR and Esr-1 genes were upregulated. Histological analysis of high-fat-diet ovaries and adrenals revealed changes in morphology with significantly increased number of cysts and reduced adrenal capsule thickness. Circulating levels of insulin, testosterone and progesterone was significantly higher in high-fat group with reduced FSH levels in plasma. These data demonstrate that high-fat feeding disrupts female reproductive function and suggest important interactions between gut and reproductive hormones in ovaries and adrenals which merit further investigation.

Stimulatory effects of vasopressin on progesterone production and BMP signaling by ovarian granulosa cells

The aim of the present study was to clarify the effects of arginine vasopressin (AVP) on ovarian steroid production and its functional relationship to the ovarian bone morphogenetic protein (BMP) system. The results showed that AVP treatment significantly increased gonadotropin- and forskolin-induced progesterone synthesis by primary culture of rat granulosa cells and human granulosa cells, respectively. In contrast, estradiol production was not significantly affected by AVP. Treatment with AVP significantly increased forskolin-induced cAMP synthesis by human granulosa cells and mRNA levels of the progesterogenic enzymes CYP11A1 and HSD3B2 in the cells. On the other hand, AVP also enhanced BMP-15-induced phosphorylation of SMAD1/5/9 and ID1 transcription. It was further revealed that the expression levels of BMP receptors, including ALK3, ALK6 and BMPR2, were upregulated by AVP. Collectively, the results indicate that AVP stimulates progesterone production via the cAMP-PKA pathway with upregulation of BMP signaling that inhibits progesterone production, which may lead to fine adjustment of progesterone biosynthesis by granulosa cells.

Liraglutide and polycystic ovary syndrome: is it only a matter of body weight?

Despite Polycystic Ovary Syndrome (PCOS) is a very prevalent disorder among women of reproductive age, there is widespread agreement that until now, no pharmacological options are available to tackle the entire spectrum of clinical manifestations encountered in the clinical practice. Obesity and insulin resistance, which commonly characterized this syndrome, prompted the design of studies investigating the effects of glucagon-like peptide 1 (GLP-1) receptor agonists (GLP-1RA) in PCOS. Indeed, a very impressive number of randomized controlled clinical trials (RCTs) and systematic reviews provided robust evidence on the effectiveness of GLP-1RA in PCOS as a new, appealing approach, producing both satisfactory and permanent weight loss, and improvement of insulin resistance at the same time. However, most of the subjects included in the RCTs are PCOS patients with obesity/overweight, whereas a portion of PCOS women, which can even reach 50%, might present a lean phenotype. Moreover, some benefits on clinical and metabolic features of PCOS may not have fully emerged due to the low or medium doses employed in the vast majority of the current studies. Thus, pitfalls in the methodology of these studies have led sometimes to misleading results. In addition, some aspects of GLP-1 beyond weight loss, such as preclinical evidence on GLP-1 effects in directly modulating the hypothalamus-pituitary-gonadal axis, or the effects of GLP-1RA on clinical and biochemical expression of hyperandrogenism, still deserve a greater insight, especially in light of a possible therapeutic use in PCOS women independently of obesity. Aim of this review is to further unravel the possible role of GLP-1 in PCOS pathogenesis, tempting to provide additional supports to the rationale of treatment with GLP-1RA in the management of PCOS also independent of weight loss. For this purpose, the outcomes of RCTs investigating in PCOS the anthropometric and metabolic changes have been treated separately to better underpin the effects of GLP-1 RA, in particular liraglutide, beyond weight loss.

Oxytocin enhances progesterone production with upregulation of BMP-15 activity by granulosa cells

To elucidate the reproductive role of oxytocin (OXT) in ovarian steroidogenesis and its functional interaction with bone morphogenetic proteins (BMPs), the effects of OXT on ovarian steroidogenesis were investigated by utilizing primary culture of rat granulosa cells and human granulosa KGN cells. Here we revealed that the OXT receptor was expressed in both rat and human granulosa cells and that OXT treatment significantly increased follicle-stimulating hormone (FSH)- and forskolin (FSK)-induced progesterone production, but not estradiol production, by rat and human granulosa cells, respectively. In accordance with the effects of OXT on progesterone production, OXT enhanced mRNA expression of CYP11A1 and HSD3B2 induced by FSK in human granulosa cells. Of note, OXT enhanced the phosphorylation of SMAD1/5/9 and the transcription of ID1 induced by BMP-15, but not those induced by BMP-6, in human granulosa cells. It was also revealed that OXT treatment upregulated the expression of BMPR2, a crucial type-II receptor of BMP-15, and enhanced the BMP-15-induced expression of inhibitory SMAD6 by human granulosa cells. Collectively, it was shown that OXT accelerates ovarian progesterone synthesis with upregulation of BMP-15 activity, leading to a fine-tuning of ovarian steroidogenesis (186 words).

Therapeutic Potential of Glucagon-like Peptide-1 Agonists in Polycystic Ovary Syndrome: From Current Clinical Evidence to Future Perspectives

Despite the continuous effort to understand the pathophysiology and determine potential therapeutic targets, PCOS treatment largely depends on lifestyle intervention and symptomatic management of individual signs and symptoms. International guidelines recognize the importance of weight reduction as a cornerstone for the achievement of better metabolic, reproductive, and cardiovascular outcomes in PCOS women who are overweight or obese. With its profound weight loss potential in patients with or without diabetes, the administration of GLP-1 receptor agonists has been investigated in overweight/obese women with PCOS in several single-center randomized control trials with considerable variation in the dosing regimen, follow-up duration, and outcome measurements over recent years. Most trials reported superior weight loss effects of GLP-1 receptor agonists compared to lifestyle changes or metformin, with additional metabolic, reproductive, and cardiovascular benefits in this population. However, their use is currently not widely accepted by the clinical community that treats this population. The major concern is how to balance the reproductive and metabolic treatment strategies since the use of GLP-1 receptor agonists requires effective contraception while on therapy and a washout period before pregnancy. Both approaches are not mutually exclusive, yet the best choice requires a careful assessment of the clinical context. Knowing a patient’s individual circumstances, precise clinical sub-phenotyping, and regular monitoring are crucial components for the safe and effective use of these new tools. In the present narrative review, we explore the current clinical evidence and provide the future perspectives and challenges for their implementation in PCOS management.

Genomic correlation, shared loci, and causal relationship between obesity and polycystic ovary syndrome: a large-scale genome-wide cross-trait analysis

BACKGROUND

The comorbidity between polycystic ovary syndrome (PCOS) and obesity has long been observed in clinical settings, but their shared genetic basis remains unclear.

METHODS

Leveraging summary statistics of large-scale GWAS(s) conducted in European-ancestry populations on body mass index (adult BMI, Nfemale=434,794; childhood BMI, N=39,620), waist-to-hip ratio (WHR, Nfemale=381,152), WHR adjusted for BMI (WHRadjBMI, Nfemale=379,501), and PCOS (Ncase=10,074, Ncontrol=103,164), we performed a large-scale genome-wide cross-trait analysis to quantify overall and local genetic correlation, to identify shared loci, and to infer causal relationship.

RESULTS

We found positive genetic correlations between PCOS and adult BMI (rg=0.47, P=2.19×10-16), childhood BMI (rg=0.31, P=6.72×10-5), and WHR (rg=0.32, P=1.34×10-10), all withstanding Bonferroni correction. A suggestive significant genetic correlation was found between PCOS and WHRadjBMI (rg=0.09, P=0.04). Partitioning the whole genome into 1703 nearly independent regions, we observed a significant local genetic correlation for adult BMI and PCOS at chromosome 18: 57630483-59020751. We identified 16 shared loci underlying PCOS and obesity-related traits via cross-trait meta-analysis including 9 loci shared between BMI and PCOS (adult BMI and PCOS: 5 loci; childhood BMI and PCOS: 4 loci), 6 loci shared between WHR and PCOS, and 5 loci shared between WHRadjBMI and PCOS. Mendelian randomization (MR) supported the causal roles of both adult BMI (OR=2.92, 95% CI=2.33-3.67) and childhood BMI (OR=2.76, 95% CI=2.09-3.66) in PCOS, but not WHR (OR=1.19, 95% CI=0.93-1.52) or WHRadjBMI (OR=1.03, 95% CI=0.87-1.22). Genetic predisposition to PCOS did not seem to influence the risk of obesity-related traits.

CONCLUSIONS

Our cross-trait analysis suggests a shared genetic basis underlying obesity and PCOS and provides novel insights into the biological mechanisms underlying these complex traits. Our work informs public health intervention by confirming the important role of weight management in PCOS prevention.

Effect of Sex Hormone-Binding Globulin on Polycystic Ovary Syndrome: Mechanisms, Manifestations, Genetics, and Treatment

Polycystic ovary syndrome (PCOS) is one of the most common endocrine diseases causing infertility in women of childbearing age. It is characterized by hyperandrogenemia (HA), chronic anovulation, and polycystic ovary morphology (PCOM). Most women with PCOS have metabolic abnormalities. Sex hormone-binding globulin (SHBG), a transport carrier that binds estrogen and androgens and regulates their biological activity, is usually used as an indicator of hyperandrogenism in women with PCOS. Low serum SHBG levels are considered a biomarker of metabolic abnormalities and are associated with insulin resistance (IR), HA, and abnormal glucose and lipid metabolism in PCOS patients. SHBG is also related to the long-term prognosis of PCOS, whereas SHBG gene polymorphism is associated with PCOS risk. In addition, the administration of metformin (MET), glucagon-like peptide-1 receptor agonists (GLP-1 RAs), thiazolidinediones (TZDs), compound oral contraceptives (COCs), as well as nutrient supplements such as inositol (MI), vitamin D, and synbiotics can regulate SHBG levels to ameliorate PCOS complications and improve prognosis. This review focuses on the interaction between SHBG and various PCOS complications as well as the regulation of SHBG by various drugs and nutrients and its therapeutic effects on PCOS.

Roles of NR5A1 and NR5A2 in the regulation of steroidogenesis by Clock gene and bone morphogenetic proteins by human granulosa cells

The functional role of the transcription factors NR5A1 and NR5A2 and their interaction with Clock gene and bone morphogenetic proteins (BMPs) were investigated in human granulosa KGN cells. Treatment with BMP-15 and GDF-9 suppressed forskolin (FSK)-induced steroidogenesis as shown by the mRNA expression levels of StAR and P450scc but not the mRNA expression level of P450arom. Of interest, treatment with BMP-15 and GDF-9 also suppressed FSK-induced NR5A2 mRNA expression. Treatment with BMP-15 suppressed NR5A2 mRNA and protein expression but increased Clock mRNA and protein expression levels by granulosa cells. The mRNA expression levels of NR5A1, but not those of NR5A2, were positively correlated with the levels of Clock mRNA, while the mRNA levels of Id-1, the target gene of BMP signaling, were positively correlated with those of NR5A1 but not with those of NR5A2. It was also demonstrated that the mRNA expression levels of NR5A1 were positively correlated with those of P450arom and 3βHSD, whereas the mRNA expression level of NR5A2 was correlated with those of StAR and P450scc. Furthermore, inhibition of Clock gene expression by siRNA attenuated the expression of NR5A1, and the mRNA levels of Clock gene were significantly correlated with those of NR5A1. Collectively, the results suggested a novel mechanism by which Clock gene expression induced by BMP-15 is functionally linked to the expression of NR5A1, whereas NR5A2 expression is suppressed by BMP-15 in granulosa cells. The interaction between Clock NR5A1/NR5A2 and BMP-15 is likely to be involved in the fine-tuning of steroidogenesis by ovarian granulosa cells.

Involvement of BMP-15 in glucocorticoid actions on ovarian steroidogenesis by rat granulosa cells

To elucidate the impact of glucocorticoids on ovarian steroidogenesis and its molecular mechanism by focusing on bone morphogenetic proteins (BMPs), we examined the effect of dexamethasone (Dex) on estradiol and progesterone synthesis by using primary culture of rat granulosa cells. It was revealed that Dex treatment dose-dependently decreased estradiol production but increased progesterone production induced by follicle-stimulating hormone (FSH) by granulosa cells. In accordance with the effects of Dex on estradiol synthesis, Dex suppressed P450arom mRNA expression and cAMP synthesis induced by FSH. Dex treatment in turn enhanced basal as well as FSH-induced levels of mRNAs encoding the enzymes for progesterone synthesis including P450scc and 3βHSD but not StAR and 20αHSD. Of note, Dex treatment significantly upregulated transcription of the BMP target gene Id-1 and Smad1/5/9 phosphorylation in the presence of BMP-15 among the key ovarian BMP ligands. It was also found that Dex treatment increased the expression level of BMP type-I receptor ALK-6 among the type-I and -II receptors for BMP-15. Inhibitory Smad6/7 expression was not affected by Dex treatment. On the other hand, BMP-15 treatment upregulated glucocorticoid receptor (GR) expression in granulosa cells. Collectively, it was revealed that glucocorticoids elicit differential effects on ovarian steroidogenesis, in which GR and BMP-15 actions are mutually enhanced in granulosa cells.

The potential role of incretin-based therapies for polycystic ovary syndrome: a narrative review of the current evidence

INTRODUCTION

Polycystic ovary syndrome (PCOS) is a common endocrine disorder that affects women of reproductive age. Metabolic consequences associated with PCOS include, but are not limited to, insulin resistance (IR), type 2 diabetes mellitus (T2DM) and cardiovascular disease (CVD). This narrative review aims to provide a comprehensive overview of the potential therapeutic roles of the incretin-based therapies in the management of PCOS.

METHODS

We performed a systematic search of databases including PubMed, MEDLINE and EMBASE up to 1 October 2020. We developed a search string of medical subject headings (MeSH) including the terms PCOS, incretin mimetics, glucagon-like peptide-1 (GLP-1), glucagon-like peptide-1 receptor antagonists (GLP-1 RAs), liraglutide, exenatide, semaglutide, dipeptidyl peptidase-4 (DPP-4) inhibitors, combined with IR, testosterone and sex hormone-binding globulin (SHBG).

RESULTS

We identified 854 relevant articles and, after the initial screening, eight interventional animal studies, one observational animal study, 14 interventional human studies, two case-control studies and one systematic review were included. These studies showed the potential significant roles of GLP-1 RAs and DPP-4 inhibitors in the management of PCOS, with significant improvements in the metabolic parameters, including substantial weight reduction and improved insulin sensitivity. These agents also improved the hormonal parameters through decreased free androgen and increased SHBG. Moreover, they improved menstrual regularity, increased fertility with enhanced ovulation and pregnancy in obese women with PCOS.

CONCLUSION

GLP-1 RAs and DPP-4 inhibitors have a promising therapeutic role in PCOS; however, larger clinical trials are needed to establish the role of incretin-based therapies in the management of PCOS.

Liraglutide: New Perspectives for the Treatment of Polycystic Ovary Syndrome

Polycystic ovary syndrome is a complex and heterogenous disorder involving multiple organ systems and different molecular pathways. It is tightly associated with obesity and especially abdominal obesity. As body weight reduction is the main modifiable risk factor for polycystic ovary syndrome, therapeutic approaches in overweight or obese women with polycystic ovary syndrome have been developed. Liraglutide is a glucagon-like peptide-1 receptor agonist that promotes sustained weight loss, as well as abdominal fat reduction, in individuals with obesity, prediabetes, and type 2 diabetes mellitus. The majority of current clinical studies have demonstrated that liraglutide therapy achieved significant reductions in body weight, body mass index, and abdominal circumference in overweight and obese women with polycystic ovary syndrome. Liraglutide therapy promoted significant improvements in free testosterone and sex hormone-binding globulin levels in some studies. Important metabolic and hormonal improvements were also reported after the combination of liraglutide with metformin. Increased menstrual frequency, as well as potential positive effects in reproduction, were described. However, the small number of participants, short duration, and low daily liraglutide dose are some of the main limitations of these studies. Larger and longer, multi-centred, double-blind, placebo-controlled trials of liraglutide monotherapy or combination therapy, with prolonged post-interventional monitoring, are crucially anticipated. Metabolic, hormonal, and reproductive primary outcomes should be uniformly addressed, to tailor future targeted treatment approaches, according to the patient phenotype and needs. This will improve long-term therapeutic outcomes in this population.

Updates on molecular and environmental determinants of luteal progesterone production

Progesterone, a critical hormone in reproduction, is a key sex steroid in the establishment and maintenance of early pregnancy and serves as an intermediary for synthesis of other steroid hormones. Progesterone production from the corpus luteum is a tightly regulated process which is stimulated and maintained by multiple factors, both systemic and local. Multiple regulatory systems, including classic mediators of gonadotropin stimulation such as the cAMP/PKA pathway and TGFβ-mediated signaling pathways, as well as local production of hormonal factors, exist to promote granulosa cell function and physiological fine-tuning of progesterone levels. In this manuscript, we provide an updated narrative review of the known mediators of human luteal progesterone and highlight new observations regarding this important process, focusing on studies published within the last five years. We will also review recent evidence suggesting that this complex system of progesterone production is sensitive to disruption by exogenous environmental chemicals that can mimic or interfere with the activities of endogenous hormones.

The role of glucagon-like peptide-1 in reproduction: from physiology to therapeutic perspective

BACKGROUND

Glucagon-like peptide-1 (GLP-1) receptor agonists (GLP-1 RAs) have become firmly established in the treatment of type 2 diabetes and obesity, disorders frequently associated with diminished reproductive health. Understanding of the role of GLP-1 and GLP-1 RAs in reproduction is currently limited and largely unaddressed in clinical studies.

OBJECTIVE AND RATIONALE

The purpose of this narrative review is to provide a comprehensive overview of the role of GLP-1 in reproduction and to address a therapeutic perspective that can be derived from these findings.

SEARCH METHODS

We performed a series of PubMed database systemic searches, last updated on 1 February 2019, supplemented by the authors' knowledge and research experience in the field. A search algorithm was developed incorporating the terms glucagon-like peptide-1, GLP-1, glucagon-like peptide-1 receptor, GLP-1R, or incretins, and this was combined with terms related to reproductive health. The PICO (Population, Intervention, Comparison, Outcome) framework was used to identify interventional studies including GLP-1 RAs and dipeptidyl peptidase-4 (DPP-4) inhibitors, which prevent the degradation of endogenously released GLP-1. We identified 983 potentially relevant references. At the end of the screening process, we included 6 observational (3 preclinical and 3 human) studies, 24 interventional (9 preclinical and 15 human) studies, 4 case reports, and 1 systematic and 2 narrative reviews.

OUTCOMES

The anatomical distribution of GLP-1 receptor throughout the reproductive system and observed effects of GLP-1 in preclinical models and in a few clinical studies indicate that GLP-1 might be one of the important modulating signals connecting the reproductive and metabolic system. The outcomes show that there is mostly stimulating role of GLP-1 and its mimetics in mammalian reproduction that goes beyond mere weight reduction. In addition, GLP-1 seems to have anti-inflammatory and anti-fibrotic effects in the gonads and the endometrium affected by obesity, diabetes, and polycystic ovary syndrome (PCOS). It also seems that GLP-1 RAs and DPP-4 inhibitors can reverse polycystic ovary morphology in preclinical models and decrease serum concentrations of androgens and their bioavailability in women with PCOS. Preliminary data from interventional clinical studies suggest improved menstrual regularity as well as increased fertility rates in overweight and/or obese women with PCOS treated with GLP-1 RAs in the preconception period.

WIDER IMPLICATIONS

GLP-1 RAs and DPP-4 inhibitors show promise in the treatment of diabetes and obesity-related subfertility. Larger interventional studies are needed to establish the role of preconception intervention with GLP-1 based therapies, assessing fertility outcomes in obesity, PCOS, and diabetes-related fertility problems. The potential impact of the dose- and exposure time-response of different GLP-1 RAs need further exploration. Future research should also investigate sex-specific variability of GLP-1 on reproductive outcomes, in particular on the gonads where the observations in males are most conflicting.

Emerging role of GIP and related gut hormones in fertility and PCOS

Gastric inhibitory polypeptide (GIP) is best known as an incretin hormone released by enteroendocrine K-cells in response to feeding and stimulates insulin release to regulate blood glucose and nutrient homeostasis. More recently GIP has been ascribed a positive role in lipid metabolism, bone strength, cardiovascular function and cognition. The present paper considers an emerging role of GIP and related gut hormones in fertility and especially polycystic ovarian syndrome (PCOS). Key evidence concerns restoration of fertility in women with gross obesity and PCOS following bariatric surgery. This is considered to reflect indirect effects mediated by alleviation of insulin resistance together with possible direct effects of surgically induced changes of GIP, GLP-1 and related peptide hormones on ovaries and the hypothalamic-pituitary-adrenal axis. Further studies are required to determine inter-relationships between the hormones and cellular mechanisms involved but these observations suggest that GIP and other gut may provide a novel therapeutic approach for PCOS and other reproductive disorders.

Effects of noopept on cognitive functions and pubertal process in rats with diabetes

AIM

Type 1 diabetes (T1DM) is a common chronic disease in childhood. Increasing insulin resistance in puberty gives rise to higher doses of insulin usage in treatment. Of this reason new approaches in treatment are needed. Noopept researches suggest it to have anti-diabetic properties. We tried to determine the effects of noopept on pubertal diabetes.

MAIN METHOD

The research was made with 60 prepubertal, 28 day-old, male, Sprague Dawley rats. The rats were divided into randomised 6 groups (n = 10/group). i) Control, ii) Diabetes Control, iii) Noopept Control, iv) Diabetes + Noopept, v) Diabetes + Insulin, vi) Diabetes + Insulin + Noopept. T1DM model was induced by streptozotocin on postnatal 28th day. 0.5 mg/kg noopept and 1 IU insulin were administered intraperitoneally for 14 days. Blood glucose and body weight measurements, puberty follow-up and MWM tests were performed. Hippocampus, hypothalamus and testis were evaluated histologically. Hypothalamic GnRH and kisspeptin were studied immunohistochemically. Serum LH, FSH and insulin, hippocampal homogenate NGF and BDNF levels were determined by ELISA.

KEY FINDINGS

Delayed puberty was normalized by noopept (p < 0.05). Blood glucose levels were lower in noopept-administered diabetic groups (p < 0.05). Noopept decreased HOMA-IR in insulin administered diabetic group (p < 0.05). Number of degenerated cells in hippocampus and testis were higher in diabetes control group when compared with other groups (p < 0.05). GnRH immunoreactivity in Diabetes + Noopept group was increased when compared to insulin + noopept group (p = 0.018). There was no difference in kisspeptin, serum LH, FSH, hippocampal NGF-BDNF levels and spatial learning assessment among groups (p > 0.05).

SIGNIFICANCE

Noopept may have positive effect in treatment of pubertal diabetes.

Interaction of ovarian steroidogenesis and clock gene expression modulated by bone morphogenetic protein-7 in human granulosa cells

A functional link between clock gene expression and ovarian steroidogenesis was studied using human granulosa KGN cells. Similarities between changes in the mRNA and protein expression levels of Bmal1 and Clock and those of Per2 and Cry1 were found in KGN cells after treatment with forskolin. Among the interrelationships between the expression levels of clock and steroidogenic factors, Clock mRNA had a strongly positive correlation with P450arom and a negative correlation with 3βHSD. Knockdown of Clock gene by siRNA resulted in a significant reduction of estradiol production by inhibiting P450arom expression, while it induced a significant increase of progesterone production by upregulating 3βHSD in KGN cells treated with forskolin. Moreover, BMP-7 had an enhancing effect on the expression of Clock mRNA and protein in KGN cells. Thus, the expression levels of Clock, being upregulated by forskolin and BMP-7, were functionally linked to estradiol production and progesterone suppression by human granulosa cells.

Effect of the interaction of metformin and bone morphogenetic proteins on ovarian steroidogenesis by human granulosa cells

In the present study, we studied the effects of metformin and its interactions with the actions of bone morphogenetic proteins (BMPs) on ovarian steroidogenesis. It was revealed that metformin treatment enhanced progesterone production by human granulosa KGN cells and rat primary granulosa cells induced by forskolin and FSH, respectively. In human granulosa cells, it was found that metformin treatment suppressed phosphorylation of Smad1/5/9 activated by BMP-15 compared with that induced by other BMP ligands. Moreover, metformin treatment increased the expression of inhibitory Smad6, but not of that Smad7, in human granulosa cells, while metformin had no significant impact on the expression levels of BMP type-I and -II receptors. Thus, the mechanism by which metformin suppresses BMP-15-induced Smad1/5/9 phosphorylation is likely, at least in part, to be upregulation of inhibitory Smad6 expression in granulosa cells. The results suggest the existence of functional interaction between metformin and BMP signaling, in which metformin enhances progesterone production by downregulating endogenous BMP-15 activity in granulosa cells.

Modulation of bone morphogenetic protein activity by melatonin in ovarian steroidogenesis

BACKGROUND

Melatonin regulates circadian and seasonal rhythms and the activities of hormones and cytokines that are expressed in various tissues, including the ovary, in which melatonin receptors are expressed. In the ovary, follicular growth occurs as a result of complex interactions between pituitary gonadotropins and autocrine and paracrine factors, including bone morphogenetic proteins (BMPs) that are expressed in the ovary.

METHODS

The effects of melatonin and BMPs on steroidogenesis were examined by using the primary cultures of rat granulosa cells.

MAIN FINDINGS RESULTS

It was shown that melatonin has antagonistic effects on BMP-6 actions in the granulosa cells, suggesting that melatonin is likely to contribute to balancing the biological activity of endogenous BMPs that maintain progesterone production and luteinization in the growing follicles. Similar interactions between melatonin and BMP-smad signaling also were shown in the mechanism of controlling ovarian steroidogenesis by other ligands.

CONCLUSION

A new role of melatonin in the regulation of endocrine homeostasis in relation to BMP activity is introduced in this review.