A possible role for AMP-activated protein kinase activated by metformin and AICAR in human granulosa cells

Role of the AMP-Activated Protein Kinase in the Pathogenesis of Polycystic Ovary Syndrome

Polycystic ovary syndrome (PCOS) is a complex disorder characterized by elevated androgen levels, menstrual irregularities, and polycystic morphology of the ovaries. Affecting 6-10% of women in childbearing age, PCOS is a leading cause of infertility worldwide. In recent years, there has been a growing acknowledgment of the involvement of adenosine monophosphate-activated protein kinase (AMPK) in the development of polycystic ovary syndrome (PCOS). The expression of AMPK is diminished in polycystic ovaries, and when AMPK is silenced in human granulosa cells, there is a rise in the expression of steroidogenic enzymes, resulting in increased production of estradiol and progesterone. Additionally, in mouse models, the inhibiting AMPK intensifies the polycystic appearance of ovaries and impairs the process of ovulation. Moreover, it has been shown that AMPK activators like metformin and resveratrol ameliorate PCOS associated signs and symptoms in experimental and clinical studies. These findings, collectively, indicate the key role of AMPK in the pathogenesis of PCOS. Understanding the role of AMPK in PCOS will offer rewarding information on details of PCOS pathogenesis and will provide novel more specific therapeutic approaches. The present review summarizes the latest findings regarding the role of AMPK in PCOS obtained in experimental and clinical studies.

Metformin: Activation of 5' AMP-activated protein kinase and its emerging potential beyond anti-hyperglycemic action

Metformin is a plant-based drug belonging to the class of biguanides and is known to treat type-2 diabetes mellitus (T2DM). The drug, combined with controlling blood glucose levels, improves the body's response to insulin. In addition, trials have identified the cardioprotective potential of metformin in the diabetic population receiving the drug. Activation of 5' AMP-activated protein kinase (AMPK) is the major pathway for these potential beneficial effects of metformin. Historically, much emphasis has been placed on the potential indications of metformin beyond its anti-diabetic use. This review aims to appraise other potential uses of metformin primarily mediated by the activation of AMPK. We also discuss various mechanisms, other than AMPK activation, by which metformin could produce beneficial effects for different conditions. Databases including PubMed/MEDLINE and Embase were searched for literature relevant to the review's objective. Reports from both research and review articles were considered. We found that metformin has diverse effects on the human body systems. It has been shown to exert anti-inflammatory, antioxidant, cardioprotective, metabolic, neuroprotective, anti-cancer, and antimicrobial effects and has now even been identified as effective against SARS-CoV-2. Above all, the AMPK pathway has been recognized as responsible for metformin's efficiency and effectiveness. Owing to its extensive potential, it has the capability to become a part of treatment regimens for diseases apart from T2DM.

Vitamin B3 (niacin), B6, C, and iron intake are associated with the free androgen index, especially in normoandrogenic polycystic ovary syndrome

Objective

Nutritional intake is one of the most common environmental risk factors of polycystic ovary syndrome (PCOS) because it is associated with obesity and insulin resistance. This study aims to determine the relationship between micronutrient intake and androgen levels associated with PCOS.

Material and Methods

This cross-sectional study was performed on 79 PCOS patients, consisted of 50 normoandrogenic (NA) and 29 hyperandrogenic (HA) patients and 66 healthy controls. Dietary intake assessment was performed using a modified 38-item semi-quantitative food frequency questionnaire. Bivariate, correlation, and multivariate analyses were performed to determine the association between study variables, and p-value less than 0.05 was considered as statistically significant difference.

Results

The baseline characteristics in all groups were similar, except for body mass index and hormonal profile, compared to those in the other groups, found to be higher in the hyperandrogenic PCOS group. There was found a significantly negative correlation between the free androgen index and intake of vitamin B1, vitamin B2, niacin, vitamin B6, calcium, and iron in the normoandrogenic PCOS group, while we did not observe it in the hyperandrogenic PCOS group. Multivariate linear regression analysis reveals that the intake of vitamin B6, vitamin C, niacin, and iron had a significant effect on the free androgen index.

Conclusion

There is an effect of micronutrient intake on androgen levels in women with PCOS. The association was more significant in the normoandrogenic PCOS than in the hyperandrogenic PCOS. These findings reveal an association between micronutrients and androgens and PCOS at a systemic level.

Investigation of Metabolome Underlying the Biological Mechanisms of Acute Heat Stressed Granulosa Cells

Heat stress affects granulosa cells and the ovarian follicular microenvironment, ultimately resulting in poor oocyte developmental competence. This study aims to investigate the metabo-lomics response of bovine granulosa cells (bGCs) to in vitro acute heat stress of 43 °C. Heat stress triggers oxidative stress-mediated apoptosis in cultured bGCs. Heat-stressed bGCs exhibited a time-dependent recovery of proliferation potential by 48 h. A total of 119 metabolites were identified through LC-MS/MS-based metabolomics of the spent culture media, out of which, 37 metabolites were determined as differentially involved in metabolic pathways related to bioenergetics support mechanisms and the physical adaptations of bGCs. Multiple analyses of metabolome data identified choline, citric acid, 3-hydroxy-3-methylglutaric acid, glutamine, and glycocyamine as being upregulated, while galactosamine, AICAR, ciliatine, 16-hydroxyhexadecanoic acid, lysine, succinic acid, uridine, xanthine, and uraconic acid were the important downregulated metabolites in acute heat stress. These differential metabolites were implicated in various important metabolic pathways directed towards bioenergetics support mechanisms including glycerophospholipid metabolism, the citrate cycle (TCA cycle), glyoxylate and dicarboxylate metabolism, and serine, threonine, and tyrosine metabolism. Our study presents important metabolites and metabolic pathways involved in the adaptation of bGCs to acute heat stress in vitro.

Comparative analysis of long non‑coding RNA expression profiles induced by resveratrol and metformin treatment for hepatic insulin resistance

Resveratrol (RSV) and metformin (MET) play a role in the treatment of diabetes; however, the mechanisms through which they mediate insulin resistance by regulating long non‑coding RNAs (lncRNAs) remain unknown. The present study was conducted to determine whether RSV and MET can improve insulin resistance in the livers of high‑fat diet (HFD)‑fed mice by regulating lncRNAs. C57BL/6J mice were fed a HFD for 8 weeks to establish a model of insulin resistance. The mice were subsequently treated with RSV or MET for 8 weeks and liver tissue samples were then collected. High‑throughput sequencing was utilized to analyze mouse liver tissue samples to obtain differential lncRNA expression profiles. RSV or MET both reduced the blood glucose levels, the insulin index and the area under the curve in HFD‑fed mice. Treatment also improved liver structure and decreased lipid deposition in liver tissues, as shown by H&E and Oil Red O staining. Compared with the MET group, there were 55 lncRNAs and 19 mRNAs with a differential expression. In total, eight lncRNAs were randomly selected and evaluated by reverse transcription‑quantitative PCR (RT‑qPCR). The results of seven lncRNAs corresponded to those of the sequencing analysis. Pathway analysis revealed that the PI3K/Akt signaling pathway had the highest enrichment score. In addition, the results of western blot analysis and RT‑qPCR revealed that the expression levels of forkhead box O1, glucose‑6‑phosphatase catalytic subunit 1 and phosphoenolpyruvate carboxykinase 1 in the RSV and MET groups were significantly decreased compared with those in the HFD group. NONMMUT034936.2 and G6PC target genes exhibited similar expression patterns, indicating that RSV and MET may affect the PI3K/Akt signaling pathway through NONMMUT034936.2 to attenuate insulin resistance. On the whole, the present study provides novel biomarkers or contemporary perspectives for the use of RSV and MET in the treatment of insulin resistance and diabetes.

MiR-1224-5p attenuates polycystic ovary syndrome through inhibiting NOD-like receptor protein 3 inflammasome activation via targeting Forkhead box O 1

Polycystic ovary syndrome (PCOS) is a common endocrine disorder that poses a great threat to women's health. MiR-1224-5p is downregulated in the follicular fluid of patients with PCOS, but its role remains largely unknown. In this study, mice were treated with dehydroepiandrosterone (DHEA) to establish an in vivo model of PCOS. We found that enhanced activation of NLRP3 inflammasome was accompanied by downregulation of miR-1224-5p in ovarian tissue of PCOS mice. The effect of miR-1224-5p was further explored in TNF-α-treated human granulosa-like tumor (KGN) cells. Upregulation of miR-1224-5p suppressed TNF-α-induced secretion of DHEA and testosterone. MiR-1224-5p attenuated TNF-α-induced inflammation by inhibiting NLRP3 inflammasome activation, IL-1β synthesis, and nuclear factor kappa B (NF-κB) p65 nuclear translocation. Notably, miR-1224-5p decreased the expression of Forkhead box O 1 (FOXO1) and its downstream gene thioredoxin interaction protein (TXNIP). Luciferase reporter assay confirmed FOXO1 as a target of miR-1224-5p. Upregulation of FOXO1 abolished miR-1224-5p-induced activation of NLRP3 inflammasome, demonstrating that miR-1224-5p might inhibit NLRP3 inflammasome activation through regulating FOXO1. This study provided novel insights into the pathogenesis of PCOS and suggested that miR-1224-5p might be a promising target for treating PCOS.

Improvement Effect of Metformin on Female and Male Reproduction in Endocrine Pathologies and Its Mechanisms

Metformin (MF), a first-line drug to treat type 2 diabetes mellitus (T2DM), alone and in combination with other drugs, restores the ovarian function in women with polycystic ovary syndrome (PCOS) and improves fetal development, pregnancy outcomes and offspring health in gestational diabetes mellitus (GDM) and T2DM. MF treatment is demonstrated to improve the efficiency of in vitro fertilization and is considered a supplementary drug in assisted reproductive technologies. MF administration shows positive effect on steroidogenesis and spermatogenesis in men with metabolic disorders, thus MF treatment indicates prospective use for improvement of male reproductive functions and fertility. MF lacks teratogenic effects and has positive health effect in newborns. The review is focused on use of MF therapy for restoration of female and male reproductive functions and improvement of pregnancy outcomes in metabolic and endocrine disorders. The mechanisms of MF action are discussed, including normalization of metabolic and hormonal status in PCOS, GDM, T2DM and metabolic syndrome and restoration of functional activity and hormonal regulation of the gonadal axis.

Anti-Trichomonas vaginalis Effect of Methanolic Extracts of Sambucus nigra in Comparison with Metronidazole

Background: Trichomoniasis is the most common non-viral sexually transmitted disease caused by a flagellated protozoan living in the genitourinary tract, which infects both men and women. Metronidazole is the treatment of choice for trichomoniasis. Researchers are seeking an alternative to metronidazole because of its inevitable side effects and toxicity. Objectives: This study aimed to evaluate the effect of the methanolic extract of Sambucus nigra against Trichomonas vaginalis in vitro. Methods: Plants were collected from different areas of Mazandaran Province, northern Iran. Fruits were separated, shade-dried, milled, and their methanolic extract was prepared in concentrations of 100, 200, 400, and 800 µg/mL. Parasites were obtained from patients referring to different health centers of Mazandaran province, cultured in Dorset medium, and incubated at 37°C. The effects were evaluated and compared to a control group. The data were analyzed by SPSS 18 using the ANOVA test. Results: The exposure time and concentration of the extracts had a direct effect on anti-parasitic activity so that increasing extract concentration and incubation time heightened the anti-trichomoniasis effects. The concentrations of 400 and 800 µg/ml of the plant had 100% efficacy after 72 and 48 hours, respectively. Conclusions: It can be concluded from our results that the methanolic extract of S. nigra has a remarkable ability to destroy T. vaginalis and it can be considered an effective drug against T. vaginalis with further studies in human and animal models.

Baicalin ameliorates polycystic ovary syndrome through AMP-activated protein kinase

Polycystic ovary syndrome (PCOS) is a complex endocrine disorder and regarded as the leading cause of anovulatory infertility. PCOS is characterized by reproductive dysfunction and metabolic disorders. Baicalin (BAL) is one of the most potent bioactive flavonoids isolated from the radix of Scutellaria baicalensis. In the present study, we investigated the potential effects of BAL on PCOS in dehydroepiandrosterone-treated rats. We found that BAL notably reduced the serum levels of free testosterone, total testosterone, follicle-stimulating hormone, luteinizing hormone, progesterone, and estradiol in PCOS rats. The increase of serum insulin level and HOMA-IR was markedly inhibited by BAL. Moreover, BAL decreased body weights, increased the number of rats with the regular estrous cycle, and ameliorated ovarian histological changes and follicular development in the DHEA-treated PCOS rats. The increase of pro-inflammatory cytokines (TNFα, IL-1β, and IL-18) and decrease of anti-inflammatory cytokine (IL-10) in PCOS rats were suppressed by BAL. BAL induced a significant decrease in the mRNA expression of steroidogenic enzymes, including 3β-HSD, CYP11A1, CYP19A1, StAR, in ovarian tissues in PCOS rats. Furthermore, BAL inhibited the decrease of AMPK protein level and phosphorylation, the decrease of Akt phosphorylation and the increase of 5α-reductase enzyme 1 expression in ovarian tissues in PCOS rats. The effects of BAL were inhibited by an inhibitor of AMPK, dorsomorphin. The upregulation of AMPK contributed to the beneficial effects of BAL. The results highlight the potential role of BAL for the intervention of PCOS.

Effect of resveratrol and metformin on ovarian reserve and ultrastructure in PCOS: an experimental study

Background

PCOS is a reproductive hormonal abnormality and a metabolic disorder. It is frequently associated with insulin resistance, hyperandrogenism, chronic inflammation, and oxidative stress. We aim to investigate the potential therapeutic effects of combined therapy of resveratrol and metformin on polycystic ovaries via SIRT1 and AMPK activation.

Methods

Wistar albino rats were divided into control and experimental (PCOS) groups. DHEA-induced PCOS rats were given resveratrol (20 mg/kg/day), metformin (300 mg/kg/day) and combined therapy. At the end of the experiment, the body and ovarian weight of rats were measured and blood samples were analyzed for FSH, LH, testosterone, AMH, TNF-α and MDA levels. Histopathological evaluation of ovaries were carried out by light and electron microscopy. SIRT1 and AMPK immunreactivity and TUNEL assay were scored. Data were statistically analyzed by SPSS programme.

Results

Metformin and combined treatment groups reduced the body and ovary weights compared to the PCOS group. Serum testosterone levels were significantly higher in the PCOS group than in the control group and this was reduced when PCOS was treated with all but especially resveratrol. All the treatment groups decreased LH, LH/FSH, TNF-α and tissue AMH levels which were induced in the PCOS group, whereas metformin was unable to improve the increased MDA and plasma AMH levels. Treatment with resveratrol and/or metformin ameliorated the elevated number of secondary and atretic follicles and the decreased number of Graafian follicles in the PCOS group, which indicates the effect of the treatments on the maintenance of folliculogenesis. Light and electron microscopic findings supported the analysis of follicular count. Increased number of TUNEL (+) granulosa cells in the PCOS group were reduced significantly in the treatment groups. Resveratrol and metformin increased SIRT1 and AMPK immunreactivity, respectively, compared to the PCOS group.

Conclusions

The results suggest that combined therapy of metformin and resveratrol may improve the weight gain, hormone profile and ovarian follicular cell architecture by inducing antioxidant and antiinflammatory systems via SIRT1 and AMPK activation in PCOS.

Vitamin D3 regulates steroidogenesis in granulosa cells through AMP-activated protein kinase (AMPK) activation in a mouse model of polycystic ovary syndrome

Polycystic ovary syndrome (PCOS) is an endocrine and metabolic disorder in reproductive-aged women. Hormonal abnormality caused by steroidogenesis disturbances appears to be the main culprit of the clinical picture in PCOS. Vitamin D3 could regulate steroidogenesis in granulosa cells, but the mechanism of action of vitamin D3 on steroidogenesis remains unknown. AMP-activated protein kinase (AMPK) has a modulating role in steroid hormone production. We investigated the effect of vitamin D3 on steroidogenesis in cultured granulosa cells of dehydroepiandrosterone-induced PCOS mice and studied the involvement of AMPK signalling pathway in the current process. Immunoblotting assay showed that vitamin D3 could increase phosphorylation of AMPK alpha and acetyl-CoA carboxylase, main substrate of AMPK. Vitamin D3 and 5-aminoimidazole-4-carboxamide-1-β-D-riboside or Aicar (AMPK activator) not only reduced gene expression of steroidogenic enzymes (P450scc or Cyp11a1, StAR, Cyp19a1 and 3B-HSD), but also reduced production of progesterone and 17B-estradiol assessed by radioimmunoassay. Pretreatment with compound C (AMPK inhibitor) decreased APMK phosphorylation and eliminated the effects of vitamin D3 and Aicar on steroidogenic enzymes expression and estradiol and progesterone production. This study showed that vitamin D3 has the main role in regulating of steroidogenesis in granulosa cells of mouse polycystic ovary through activation of the AMPK signalling pathway.

SIGNIFICANCE OF THE STUDY

Polycystic ovarian syndrome (PCOS) is an endocrine disorder of women in reproductive age. This disorder is partly related to disruption in steroidogenesis pathway and dysregulation of estradiol and progesterone production in granulosa cells of polycystic ovaries. Previously, we have shown that vitamin D3 could modulate steroidogenesis pathway in PCOS granulosa cells. In this study, we investigate the molecular mechanism of vitamin D3 in regulation of steroidogenesis pathway. We have shown that vitamin D3 has a modulating role in steroidogenesis pathway of granulosa cells by regulation of AMP-activated protein kinase (AMPK) as an underlying molecular mechanism in mouse polycystic ovary.

Insulin signalling and glucose transport in the ovary and ovarian function during the ovarian cycle

Data derived principally from peripheral tissues (fat, muscle and liver) show that insulin signals via diverse interconnecting intracellular pathways and that some of the major intersecting points (known as critical nodes) are the IRSs (insulin receptor substrates), PI3K (phosphoinositide kinase)/Akt and MAPK (mitogen-activated protein kinase). Most of these insulin pathways are probably also active in the ovary and their ability to interact with each other and also with follicle-stimulating hormone (FSH) and luteinizing hormone (LH) signalling pathways enables insulin to exert direct modulating influences on ovarian function. The present paper reviews the intracellular actions of insulin and the uptake of glucose by ovarian tissues (granulosa, theca and oocyte) during the oestrous/menstrual cycle of some rodent, primate and ruminant species. Insulin signals through diverse pathways and these are discussed with specific reference to follicular cell types (granulosa, theca and oocyte). The signalling pathways for FSH in granulosa cells and LH in granulosa and theca cells are summarized. The roles of glucose and of insulin-mediated uptake of glucose in folliculogenesis are discussed. It is suggested that glucose in addition to its well-established role of providing energy for cellular function may also have insulin-mediated signalling functions in ovarian cells, involving AMPK (AMP-dependent protein kinase) and/or hexosamine. Potential interactions of insulin signalling with FSH or LH signalling at critical nodes are identified and the available evidence for such interactions in ovarian cells is discussed. Finally the action of the insulin-sensitizing drugs metformin and the thiazolidinedione rosiglitazone on follicular cells is reviewed.

Intravaginal administration of metformin hydrochloride loaded cationic niosomes amalgamated with thermosensitive gel for the treatment of polycystic ovary syndrome: In vitro and in vivo studies

BACKGROUND AND OBJECTIVE

Metformin hydrochloride (MTF-HCl) is extensively recommended by physicians for the treatment of polycystic ovary syndrome (PCOS). Mechanistically, MTF-HCl activates AMP-dependent kinase-α (AMPK-α) pathway to decrease the glucose production, enhances fatty acid oxidation and elevates the uptake of glucose in tissues. However, despite favourable physicochemical properties, oral administration of MTF-HCl is associated with impaired bioavailability (50-60%), lactic-acidosis and frequent dosing (500mg 2-3 times a day) in PCOS that ultimately influence the patient compliance. Therefore, in present investigation, MTF-HCl loaded unmodified and cationic small unilamellar niosomes were separately amalgamated with thermosensitive gel (MTF-HCl-SUNs-Gel and MTF-HCl-C-SUNs-Gel) for the treatment of PCOS through vaginal route of administration.

METHODS AND RESULTS

MTF-HCl-SUNs and MTF-HCl-C-SUNs were separately prepared by reverse phase evaporation method. The nanovesicle size and zeta-potential of MTF-HCl-C-SUNs were measured to be 210.3±14.8-nm (P<0.05) and +8.7±2.7-mV (P<0.001), significantly higher than 198.5±20.3-nm and -16.6±3.9-mV of MTF-HCl-SUNs, respectively. Moreover, promising results of in vitro characterization parameters like gelation time, gelling temperature, viscosity analysis, percent mucoadhesiveness and drug release of MTF-HCl-C-SUNs-Gel and MTF-HCl-SUNs-Gel ensured the candidature of tailored gels for further in vivo investigations. In this way, treatment of PCOS rats under scheduled dose-dosage regimen with oral MTF-HCl solution, intravaginal MTF-HCl-SUNs-Gel and intravaginal MTF-HCl-C-SUNs-gel exhibited remarkable alterations, recruitment and development of normal follicles in addition to normalization of level of various hormones in PCOS.

CONCLUSION

In conclusion, MTF-C-SUNs-Gel has paved the way for developing intravaginal dosage form of MTF-HCl for the treatment of PCOS.

Erythropoietin and mTOR: A "One-Two Punch" for Aging-Related Disorders Accompanied by Enhanced Life Expectancy

Life expectancy continues to increase throughout the world, but is accompanied by a rise in the incidence of non-communicable diseases. As a result, the benefits of an increased lifespan can be limited by aging-related disorders that necessitate new directives for the development of effective and safe treatment modalities. With this objective, the mechanistic target of rapamycin (mTOR), a 289-kDa serine/threonine protein, and its related pathways of mTOR Complex 1 (mTORC1), mTOR Complex 2 (mTORC2), proline rich Akt substrate 40 kDa (PRAS40), AMP activated protein kinase (AMPK), Wnt signaling, and silent mating type information regulation 2 homolog 1 (Saccharomyces cerevisiae) (SIRT1), have generated significant excitement for furthering novel therapies applicable to multiple systems of the body. Yet, the biological and clinical outcome of these pathways can be complex especially with oversight of cell death mechanisms that involve apoptosis and autophagy. Growth factors, and in particular erythropoietin (EPO), are one avenue under consideration to implement control over cell death pathways since EPO can offer potential treatment for multiple disease entities and is intimately dependent upon mTOR signaling. In experimental and clinical studies, EPO appears to have significant efficacy in treating several disorders including those involving the developing brain. However, in mature populations that are affected by aging-related disorders, the direction for the use of EPO to treat clinical disease is less clear that may be dependent upon a number of factors including the understanding of mTOR signaling. Continued focus upon the regulatory elements that control EPO and mTOR signaling could generate critical insights for targeting a broad range of clinical maladies.