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

Synergistic effects of Metformin and Forskolin on oxidative stress induced by diabetes and hepatocellular cancer: An animal study

AIM

This study proposed to assess the synergistic effects of Forskolin and Metformin (alone and in combination) on glucose, hematological, liver serum, and oxidative stress parameters in diabetic, healthy, and hepatocellular carcinoma (HCC) induced rats.

MATERIALS AND METHODS

Eighty male Wistar rats were divided into 10 experimental groups (8 rats for each group), including 1) healthy group, 2) diabetic group, 3) HCC group, 4) diabet + Metformin (300 mg/kg), 5) diabet + Forskolin (100 mg/kg), 6) diabet + Metformin (300 mg/kg) & Forskolin (100 mg/kg), 7) HCC + Metformin (300 mg/kg), 8) HCC + Forskolin (100 mg/kg), 9) HCC + Metformin (300 mg/kg) & Forskolin (100 mg/kg), and 10) healthy group + Metformin (300 mg/kg) & Forskolin (100 mg/kg). The rats were administrated Forskolin/Metformin daily for 8 weeks. Glucose, hematological, and liver serum parameters were measured and compared among the groups. The levels of malondialdehyde (MDA), and the activities of superoxide dismutase (SOD) and glutathione peroxidase (GPx), as well as 8-hydroxydeoxyguanosine (8 OHdG) levels, were also measured.

RESULTS

The average blood glucose reduction in diabetic rats with the Forskolin, Metformin, and Forskolin + Metformin treatments was 43.5%, 47.1%, and 53.9%, respectively. These reduction values for HCC rats after the treatments were 21.0%, 16.2%, and 23.7%, respectively. For all the diabetic and HCC rats treated with Forskolin/Metformin, the MDA, SOD, and GPx levels showed significant improvement compared with the diabetic and HCC groups (P < 0.05). Although the rats treated with Forskolin + Metformin experienced a higher reduction in oxidative stress of blood and urine samples compared to the Forskolin group, the differences between this group and rats treated with Metformin were not significant for all parameters.

CONCLUSION

Metformin and Forskolin reduced oxidative stress in diabetic and HCC-induced rats. The results indicated that the combination of agents (Metformin & Forskolin) had greater therapeutic effects than Forskolin alone in reducing glucose levels in diabetic rats. However, the ameliorative effects of combining Metformin and Forskolin on blood and urine oxidative stress were not statistically higher than those of Metformin alone.

Metformin: Therapeutic profile in the treatment of type 2 diabetes

Metformin (dimethyl-biguanide) can claim its origins in the use of Galega officinalis as a plant treatment for symptoms ascribed to diabetes. Since the first clinical use of metformin as a glucose-lowering agent in 1957, this medicine has emerged as a first-line pharmacological option to support lifestyle interventions in the management of type 2 diabetes (T2D). It acts through multiple cellular pathways, principally in the gut, liver and muscle, to counter insulin resistance and lower blood glucose without weight gain or risk of overt hypoglycaemia. Other effects include improvements in lipid metabolism, decreased inflammation and lower long-term cardiovascular risk. Metformin is conveniently combined with other diabetes medications, can be prescribed in prediabetes to reduce the risk of progression to T2D, and is used in some regions to assist glycaemic control in pregnancy. Consistent with its diversity of actions, established safety profile and cost-effectiveness, metformin is being assessed for further possible clinical applications. The use of metformin requires adequate renal function for drug elimination, and may cause initial gastrointestinal side effects, which can be moderated by taking with meals or using an extended-release formulation. Thus, metformin serves as a valuable therapeutic resource for use throughout the natural history of T2D.

A novel action of insulin sensitizing drug as a potential promotor of preovulatory follicles, ovulation rate and prolificacy in sheep

The effect of the insulin-sensitizing drug metformin on preovulatory follicle (POF) number, ovulation rate, fetal rate and prolificacy was studied in forty-six cyclic Malpura ewes. After estrus synchronization, the ewes were equally divided into two groups (n = 23). The treatment group (MET) received a daily oral dose of metformin at a rate of 500 mg/animal for approximately 12 weeks, spanning five estrous cycles, as against untreated control (CON). All the ewes were bred to proven rams at the end of treatment. Ovarian ultrasound scans were performed at each estrus and day 9 of each cycle to assess the number and diameter of POFs and corpora lutea (CL), respectively. A comprehensive assessment of circulating hormones including, estradiol, progesterone, androstenedione, and insulin as well as metabolic indicators such as glucose, and lipid profile parameters was performed. At the end of treatment on the day of estrus (E5D0), the treatment showed a stimulatory effect on follicular development with a 53.2% (P < 0.001) increase in the number of POFs. It also increased the ovulation rate by 67.4% (P < 0.01), with a higher proportion (χ2df1 = 10.7, P < 0.001) of ewes in the MET group having multiple ovulations compared to the CON group (82.6 vs. 30.4%). With 1.48 ± 0.12 prolificacy rate in MET ewes, the proportion of ewes giving birth to multiple lambs was 2.9-fold higher than in the CON group. Plasma estradiol, insulin, glucose, total cholesterol, and LDL-cholesterol concentrations were lower (P < 0.05) in the MET ewes than in the CON. The results of the present study indicate that metformin can increase the number of POF, ovulation rate, fetal rate and prolificacy in ewes, while reducing the plasma estradiol, insulin, glucose and cholesterol in MET ewes.

Metformin improves d-galactose induced premature ovarian insufficiency through PI3K-Akt-FOXO3a pathway

PURPOSE

Metformin (MET), a first-line treatment for type 2 diabetes mellitus, restores ovarian function in women with polycystic ovary syndrome. MET has been shown to increase the rate of success for in vitro fertilization when utilized in assisted reproductive technologies. This study was designed to examine the impact of MET on ovarian function and fertility in a mouse model of galactose-induced premature ovarian insufficiency (POI). We further investigated the underlying mechanisms.

MATERIALS AND METHODS

Female mice were divided into 4 groups: saline, d-galactose, d-galactose ​+ ​MET, and MET. Body weight, ovarian index, and fertility were assessed. The hormonal profile was done. Advanced glycation end products (AGEPs), receptor for advanced glycation end products (RAGE), phosphoinositide 3-kinase (PI3K), protein kinase B (Akt), forkhead box O3a (FOXO3a) expression were measured. Ovarian follicle counting and morphology were analyzed. Immunohistochemistry of cleaved caspase-3 expression was performed.

RESULTS

Our findings demonstrated that MET reversed irregularities in the estrus cycle, enhanced the ovarian index, and improved the abnormal levels of hormones and AGEs induced by d-galactose. Furthermore, the expression levels of PI3K, Akt, FOXO3a, and RAGE were upregulated with d-galactose. However, MET attenuated their expression levels. The primordial follicles ratio was improved, whereas atretic follicles and apoptotic-related cleaved caspase-3 expression were decreased in the d-galactose ​+ ​MET group compared to the d-galactose group.

CONCLUSION

This study demonstrates that MET partially rescued ovarian dysfunction and apoptosis induced by d-galactose via a mechanism involving PI3K-Akt-FOXO3a pathway. Our finding proposed that MET may be a promising alternative treatment for POI.

Prophylactic administration of metformin reduces gestational diabetes mellitus incidence in the high-risk populations: a meta-analysis : Metformin for gestational diabetes prevention

Metformin exerts a good efficacy for gestational diabetes mellitus (GDM) treatment by regulating gluconeogenesis and insulin resistance, while no consensus about its preventive effect on GDM is reached yet. Thus, this meta-analysis aimed to comprehensively investigate the prophylactic administration of metformin in pregnant women at high risk of GDM. Databases (EMBASE, PubMed, Cochrane, CNKI, Wanfang, CQVIP) were searched to screen papers concerning the GDM prevention using metformin in women at high risk of GDM (polycystic ovary syndrome (PCOS), obese, and pregestational insulin resistance patients) until January 2023. Our study showed that five cohort studies and fifteen randomized controlled trials (RCTs) involving 3911 women were included. Pooled analysis showed that prophylactic metformin treatment (vs. control treatment) greatly reduced GDM rate (relative risk (RR) = 0.59, 95% confidence intervals (CI): 0.43-0.80). Subgroup analyses also revealed that prophylactic metformin treatment (vs. control treatment) decreased the GDM rate in the following patients' types: (1) in Asians (RR = 0.31, 95% CI: 0.23-0.41), (2) in PCOS patients (RR = 0.42, 95% CI: 0.26-0.68), and (3) in patients receiving high dose of metformin (mean dose > 1000 mg) (RR = 0.59, 95% CI: 0.42-0.83). Concerning the quality of involved studies, the overall risk of bias was low. Egger's test implied that no publication bias existed in the findings. Moreover, sensitivity analysis suggested the pleasing robustness of the results. In conclusion, prophylactic metformin reduces GDM incidence in high-risk pregnant women, indicating its early-application benefits.

The role of the thyroid in polycystic ovary syndrome

Polycystic ovary syndrome (PCOS) is the most common endocrine and metabolic disease in women of childbearing age and can cause metabolic disorder, infertility, and increased anxiety and depression; as a result, it can seriously affect the physical and mental health of fertile women. PCOS is a highly clinically heterogeneous disease with unclear etiology and pathogenesis, which increases the difficulty of treatment. The thyroid gland has complex regulatory effects on metabolism, reproduction, and emotion, and produces hormones that act on almost all cells of the human body. The clinical manifestations of PCOS are similar to some thyroid diseases. Furthermore, some thyroid diseases, such as subclinical hypothyroidism (SCH), not only increase the incidence rate of PCOS, but also exacerbate its associated metabolic abnormalities and reproductive disorders. Interestingly, PCOS also increases the incidence of some thyroid diseases. However, the role of the thyroid in PCOS remains unclear. This review is intended to thoroughly explore the critical role of the thyroid in PCOS by summarizing the comorbidity of PCOS and thyroid diseases and their combined role in metabolic disorders, related metabolic diseases, and reproductive disorders; and by analyzing the potential mechanism through which the thyroid influences the development and progression of PCOS and its symptoms. We hope this review will provide a valuable reference for the role of the thyroid in PCOS.

Beneficial effects of metformin on mice female fertility after a high-fat diet intake

Female fertility is highly dependent on energy balance. High fat diet (HFD) intake entails a risk of infertility and ovulatory disorders. Considering the increase in the prevalence of overweight and obesity over the last decades, it is crucial to understand the mechanisms involved in overweight-associated infertility. In this study, we evaluated the reproductive performance of female mice fed with a HFD and the effects of metformin administration on ovarian function in these mice. We hypothesized that one of the mechanisms involved in subfertility due to a HFD intake is the alteration of ovarian blood vessel formation. We found that mice fed with HFD had altered estrous cycles and steroidogenesis, increased ovarian fibrosis, fewer pups per litter and require more time to achieve pregnancy. HFD-fed mice also presented dysregulated ovarian angiogenesis and an increase in nuclear DNA damage in ovarian cells. Ovulation rates were lower in these animals, as evidenced both in natural mating and after ovulation induction with gonadotropins. Metformin ameliorated ovarian angiogenesis, improved steroidogenesis, fibrosis, and ovulation, decreased the time to pregnancy and increased litter sizes in HFD-fed mice. We conclude that ovarian angiogenesis is one of the mechanisms detrimentally affected by HFD intake. Since metformin could improve ovarian microvasculature, it may be an interesting strategy to study in women to shed light on new targets for patients with metabolic disturbances.

Effect of Metformin (MTF) Intervention During Pregnancy in Women With Polycystic Ovarian Syndrome (PCOS): A Systematic Review

Metformin (MTF) is a commonly prescribed medication for women with polycystic ovarian syndrome (PCOS), but its impact on pregnancy outcomes in women with PCOS remains controversial. This systematic review aims to evaluate the effects of MTF intervention on pregnancy outcomes in women with PCOS and the impact of MTF on offspring. A comprehensive search is conducted in PubMed, Google Scholar, and ScienceDirect databases from 2019 up to May 16, 2023. Only review articles and meta-analyses are included, focusing on women with PCOS who received MTF during pregnancy or as part of infertility treatment. The primary outcomes of interest are clinical pregnancy rate (CPR), miscarriage rate, preterm birth rate, and live birth rate. Secondary outcomes are the safety profile of MTF. Data extraction and quality assessment are performed following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines and the assessment using the multiple systematic reviews (AMSTAR) 2 tool, respectively. The initial search produced 1877 studies. Thirteen studies were included in the review. While the use of MTF during pregnancy in women with PCOS may have some benefits in reducing certain pregnancy complications such as pregnancy-induced hypertension (PIH), gestational diabetes mellitus (GDM), preeclampsia, preterm delivery, reducing the risk of ovarian hyperstimulation syndrome (OHSS) in women with PCOS undergoing in vitro fertilization (IVF); however, there is no significant difference in clinical pregnancy and live birth rates overall, but subgroup analysis suggests potential benefits for women with a higher body mass index (BMI). MTF is associated with a larger fetal head circumference and potential long-term effects on offspring's BMI and obesity. Further research is needed to better understand the optimal dosing of MTF, long-term effects, and effects in specific subgroups. The heterogeneity of the included studies limited the ability to analyze the data effectively, leading to challenges in drawing definitive conclusions.

Hippo Signaling in the Ovary: Emerging Roles in Development, Fertility, and Disease

Emerging studies indicate that the Hippo pathway, a highly conserved pathway that regulates organ size control, plays an important role in governing ovarian physiology, fertility, and pathology. Specific to the ovary, the spatiotemporal expression of the major components of the Hippo signaling cascade are observed throughout the reproductive lifespan. Observations from multiple species begin to elucidate the functional diversity and molecular mechanisms of Hippo signaling in the ovary in addition to the identification of interactions with other signaling pathways and responses to various external stimuli. Hippo pathway components play important roles in follicle growth and activation, as well as steroidogenesis, by regulating several key biological processes through mechanisms of cell proliferation, migration, differentiation, and cell fate determination. Given the importance of these processes, dysregulation of the Hippo pathway contributes to loss of follicular homeostasis and reproductive disorders such as polycystic ovary syndrome (PCOS), premature ovarian insufficiency, and ovarian cancers. This review highlights what is currently known about the Hippo pathway core components in ovarian physiology, including ovarian development, follicle development, and oocyte maturation, while identifying areas for future research to better understand Hippo signaling as a multifunctional pathway in reproductive health and biology.

The role of AMPK-dependent pathways in cellular and molecular mechanisms of metformin: a new perspective for treatment and prevention of diseases

Metformin can suppress gluconeogenesis and reduce blood sugar by activating adenosine monophosphate-activated protein kinase (AMPK) and inducing small heterodimer partner (SHP) expression in the liver cells. The main mechanism of metformin’s action is related to its activation of the AMPK enzyme and regulation of the energy balance. AMPK is a heterothermic serine/threonine kinase made of a catalytic alpha subunit and two subunits of beta and a gamma regulator. This enzyme can measure the intracellular ratio of AMP/ATP. If this ratio is high, the amino acid threonine 172 available in its alpha chain would be activated by the phosphorylated liver kinase B1 (LKB1), leading to AMPK activation. Several studies have indicated that apart from its significant role in the reduction of blood glucose level, metformin activates the AMPK enzyme that in turn has various efficient impacts on the regulation of various processes, including controlling inflammatory conditions, altering the differentiation pathway of immune and non-immune cell pathways, and the amelioration of various cancers, liver diseases, inflammatory bowel disease (IBD), kidney diseases, neurological disorders, etc. Metformin’s activation of AMPK enables it to control inflammatory conditions, improve oxidative status, regulate the differentiation pathways of various cells, change the pathological process in various diseases, and finally have positive therapeutic effects on them. Due to the activation of AMPK and its role in regulating several subcellular signalling pathways, metformin can be effective in altering the cells’ proliferation and differentiation pathways and eventually in the prevention and treatment of certain diseases.

Metformin Intervention—A Panacea for Cancer Treatment?

The molecular mechanism of action and the individual influence of various metabolic pathways related to metformin intervention are under current investigation. The available data suggest that metformin provides many advantages, exhibiting anti-inflammatory, anti-cancer, hepatoprotective, cardioprotective, otoprotective, radioprotective, and radio-sensitizing properties depending on cellular context. This literature review was undertaken to provide novel evidence concerning metformin intervention, with a particular emphasis on cancer treatment and prevention. Undoubtedly, the pleiotropic actions associated with metformin include inhibiting inflammatory processes, increasing antioxidant capacity, and improving glycemic and lipid metabolism. Consequently, these characteristics make metformin an attractive medicament to translate to human trials, the promising results of which were also summarized in this review.

Mersal E, Razik H. Farrag A, M. Abdelmoneim A, M. Abdelmenem A, S. Salim M. Histomorphological Changes in a Rat Model of Polycystic Ovary Syndrome and the Contribution of Stevia Leaf Extract in Modulating the Ovarian Fibrosis, VEGF, and TGF-β Immunoexpressions: Comparison with Metformin

Polycystic ovary syndrome (PCOS) is a common endocrine disorder of fertile females. It has been reported that stevia leaf extract (SLE) has antidiabetic and antihyperlipidemic properties. Therefore, the current study hypothesized and investigated the role and mechanistic aspects of a natural sweetener; SLE in treating a rat model of letrozole-induced PCOS and to compare it with metformin. Thirty-five female Wistar albino rats were divided into 5 groups: control, PCOS-induced group (letrozole, 1 mg/kg/d, for 21 days), SLE, metformin, and combination-treated groups (300 mg/kg/d, for the next 28 days in SLE and metformin-treated groups). Vaginal smears were done. The levels of glucose, lipid, and hormonal profiles were measured in the serum meanwhile, malonyl dialdehyde (MDA), superoxide dismutase (SOD), and tumour necrosis factor (TNF-α) were measured in the ovary. Ovarian sections were subjected to hematoxylin and eosin, Masson, and immunohistochemical identification of VEGF and TGF-β followed by morphometric analysis. PCOS rats showed altered hormonal and lipid profiles, in addition to hyperglycemia. Also, the ovarian tissue levels of MDA and TNF-α were elevated, and SOD was decreased. Numerous cystic follicles, decrease/absence of corpora lutea, interstitial fibrosis with positive VEGF and TGF-β immunoreactivity were evident. SLE improved all altered parameters. SLE showed potential therapeutic merits in letrozole-induced PCOS via anti-inflammatory, antioxidant, anti-fibrotic, and angiogenesis regulating mechanisms. Its effects were almost comparable to metformin, and the combination of both has no further synergistic effect.

Metformin disrupts insulin secretion, causes proapoptotic and oxidative effects in rat pancreatic beta-cells in vitro

Metformin is the first-line drug to treat type 2 diabetes mellitus. Its mechanism of action is still debatable, and recent studies report that metformin attenuates oxidative stress. This study evaluated the in vitro antioxidant effects of a broad range of metformin concentrations on insulin-producing cells. The cell cycle, metabolism, glucose-stimulated insulin secretion, and cell death were evaluated to determine the biguanide effects on beta-cell function and survival. Antioxidant potential was based on reactive oxygen species (ROS), reduced glutathione (GSH), oxidative stress biomarker levels, and antioxidant enzyme and transcriptional factor Nrf2 activities. The results demonstrate that metformin disrupted GSIS in a concentration-dependent manner, lowered insulin content, and attenuated beta-cell metabolism. At high concentrations, metformin induced cell death and cell cycle arrest as well as increased ROS generation, consequently reducing GSH content. Although carbonylated protein content was elevated, indicating oxidative stress, the antioxidant enzyme and Nrf2 activities were not altered. In conclusion, our results show that metformin disrupts pancreatic beta-cell functionality but does not exert a putative antioxidant effect. It is important to note that the drug could potentially affect beta-cells, especially at high circulating levels.

Comparative Study of the Restoring Effect of Metformin, Gonadotropin, and Allosteric Agonist of Luteinizing Hormone Receptor on Spermatogenesis in Male Rats with Streptozotocin-Induced Type 2 Diabetes Mellitus

We compared the effectiveness of human chorionic gonadotropin (hCG; 5 days, 20 IU/rat/day), allosteric luteinizing hormone receptor agonist TP04 (5 days, 20 mg/kg/day), and metformin (28 days, 120 mg/kg/day) in restoring spermatogenesis in male rats with type 2 diabetes mellitus. hCG and TP04 increased the levels of testosterone and expression of the steroidogenic protein StAR, the number of spermatogenic cells, thickness of the seminal epithelium, and the number and motility of mature sperm that were reduced in diabetic rats, though they did not reduce the number of defective spermatozoa. Metformin had a weak effect on steroidogenesis, but was not inferior to luteinizing hormone receptor agonist by its restorative effect on spermatogenesis and also reduced the number of defective forms of spermatozoa. Thus, the spermatogenesis-restoring effect of metformin and luteinizing hormone receptor agonist in type 2 diabetes mellitus are comparable, despite different mechanisms of action.

Obesity and Male Reproduction: Do Sirtuins Play a Role?

Obesity is a major current public health problem of global significance. A progressive sperm quality decline, and a decline in male fertility, have been reported in recent decades. Several studies have reported a strict relationship between obesity and male reproductive dysfunction. Among the many mechanisms by which obesity impairs male gonadal function, sirtuins (SIRTs) have an emerging role. SIRTs are highly conserved nicotinamide adenine dinucleotide (NAD+)-dependent deacetylases that play a role in gene regulation, metabolism, aging, and cancer. SIRTs regulate the energy balance, the lipid balance, glucose metabolism, and adipogenesis, but current evidence also indicates a role for SIRTs in male reproduction. However, the majority of the studies have been conducted in animal models and very few have been conducted with humans. This review shows that SIRTs play an important role among the molecular mechanisms by which obesity interferes with male fertility. This highlights the need to deepen this relationship. It will be of particular interest to evaluate whether synthetic and/or natural compounds capable of modifying the activity of SIRTs may also be useful for the treatment of obesity and its effects on gonadal function. Although few studies have explored the role of SIRT activators in obesity-induced male infertility, some molecules, such as resveratrol, appear to be effective in modulating SIRT activity, as well as counteracting the negative effects of obesity on male fertility. The search for strategies to improve male reproductive function in overweight/obese patients is a challenge and understanding the role of SIRTs and their activators may open new interesting scenarios in the coming years.

A Prospective Cohort Study of Metformin as an Adjuvant Therapy for Infertile Women With Endometrial Complex Hyperplasia/Complex Atypical Hyperplasia and Their Subsequent Assisted Reproductive Technology Outcomes

OBJECTIVE

To investigate the adjuvant efficacy of metformin treatment to achieve pathological complete response (CR) in patients with endometrial complex hyperplasia (CH) and complex atypical hyperplasia (CAH), and secondarily, to evaluate their pregnancy outcomes after following assisted reproductive technology (ART).

STUDY DESIGN

This prospective cohort study analyzed 219 patients diagnosed with infertility and CH/CAH from January 2016 to December 2020. Among these patients, 138 were assigned to the control group (progesterone alone) and 81 were assigned to the study group (progesterone+metformin). After 8/12 weeks of therapy, the treatment responses were assessed by histological examination of curettage specimens obtained by hysteroscopy. Once the pathological results indicated CR, the patients were able to receive ART. The ART treatment and follow-up data of these patients were collected and analyzed.

RESULTS

116 patients in the control group achieved CR, compared with 76 patients in the study group. The CR rate in the control group was significantly lower than that in the study group (P=0.034). We then divided the patients into subgroups to compare the treatment responses. In the subgroup analyses, patients with body mass index (BMI) ≥25 kg/m² and patients with polycystic ovarian syndrome (PCOS) had higher CR rates in the metformin group compared with the control group (P=0.015, P=0.028 respectively). Subsequently, 68 patients in the control group and 47 patients in the study group received an ART cycle. We examined the pregnancy indications and found no significant differences in the clinical pregnancy rate and live birth rate between the two groups (P>0.05).

CONCLUSION

Regression of CH/CAH may be improved by progesterone+metformin compared with progesterone alone. The effect was particularly pronounced in patients with BMI ≥25 kg/m² and patients with PCOS. Metformin had no obvious effect on subsequent ART outcomes. The trial is registered on the publicly accessible website.

CLINICAL TRIAL REGISTRATION

http://www.chictr.org.cn/showproj.aspx?proj=15372, identifier ChiCTR-ONR-16009078.

The Effects of Separate and Combined Treatment of Male Rats with Type 2 Diabetes with Metformin and Orthosteric and Allosteric Agonists of Luteinizing Hormone Receptor on Steroidogenesis and Spermatogenesis

In men with type 2 diabetes mellitus (T2DM), steroidogenesis and spermatogenesis are impaired. Metformin and the agonists of luteinizing hormone/human chorionic gonadotropin(hCG)-receptor (LH/hCG-R) (hCG, low-molecular-weight allosteric LH/hCG-R-agonists) can be used to restore them. The aim was to study effectiveness of separate and combined administration of metformin, hCG and 5-amino-N-tert-butyl-2-(methylsulfanyl)-4-(3-(nicotinamido)phenyl)thieno[2,3-d]pyrimidine-6-carboxamide (TP3) on steroidogenesis and spermatogenesis in male rats with T2DM. hCG (15 IU/rat/day) and TP3 (15 mg/kg/day) were injected in the last five days of five-week metformin treatment (120 mg/kg/day). Metformin improved testicular steroidogenesis and spermatogenesis and restored LH/hCG-R-expression. Compared to control, in T2DM, hCG stimulated steroidogenesis and StAR-gene expression less effectively and, after five-day administration, reduced LH/hCG-R-expression, while TP3 effects changed weaker. In co-administration of metformin and LH/hCG-R-agonists, on the first day, stimulating effects of LH/hCG-R-agonists on testosterone levels and hCG-stimulated expression of StAR- and CYP17A1-genes were increased, but on the 3-5th day, they disappeared. This was due to reduced LH/hCG-R-gene expression and increased aromatase-catalyzed estradiol production. With co-administration, LH/hCG-R-agonists did not contribute to improving spermatogenesis, induced by metformin. Thus, in T2DM, metformin and LH/hCG-R-agonists restore steroidogenesis and spermatogenesis, with metformin being more effective in restoring spermatogenesis, and their co-administration improves LH/hCG-R-agonist-stimulating testicular steroidogenesis in acute but not chronic administration.

Integrated or Independent Actions of Metformin in Target Tissues Underlying Its Current Use and New Possible Applications in the Endocrine and Metabolic Disorder Area

Metformin is considered the first-choice drug for type 2 diabetes treatment. Actually, pleiotropic effects of metformin have been recognized, and there is evidence that this drug may have a favorable impact on health beyond its glucose-lowering activity. In summary, despite its long history, metformin is still an attractive research opportunity in the field of endocrine and metabolic diseases, age-related diseases, and cancer. To this end, its mode of action in distinct cell types is still in dispute. The aim of this work was to review the current knowledge and recent findings on the molecular mechanisms underlying the pharmacological effects of metformin in the field of metabolic and endocrine pathologies, including some endocrine tumors. Metformin is believed to act through multiple pathways that can be interconnected or work independently. Moreover, metformin effects on target tissues may be either direct or indirect, which means secondary to the actions on other tissues and consequent alterations at systemic level. Finally, as to the direct actions of metformin at cellular level, the intracellular milieu cooperates to cause differential responses to the drug between distinct cell types, despite the primary molecular targets may be the same within cells. Cellular bioenergetics can be regarded as the primary target of metformin action. Metformin can perturb the cytosolic and mitochondrial NAD/NADH ratio and the ATP/AMP ratio within cells, thus affecting enzymatic activities and metabolic and signaling pathways which depend on redox- and energy balance. In this context, the possible link between pyruvate metabolism and metformin actions is extensively discussed.

Metformin-enhances resilience via hormesis

The present paper demonstrates that metformin (MF) induced a broad spectrum of hormetic biphasic dose responses in a wide range of experimental studies, affecting multiple organ systems, cell types, and endpoints enhancing resilience to chemical stresses in preconditioning and co-current exposure protocols. Detailed mechanistic evaluations indicate that MF-induced hormetic-adaptive responses are mediated often via the activation of adenosine monophosphate-activated kinase (AMPK) protein and its subsequent upregulation of nuclear factor erythroid 2-related factor 2 (Nrf2). Hormesis-induced protective responses by MF are largely mediated via a vast and highly integrated anti-inflammatory molecular network that enhances longevity and delays the onset and slows the progression of neurodegenerative and other chronic diseases.

In Utero Exposure to Metformin Reduces the Fertility of Male Offspring in Adulthood

Metformin is a drug used for the treatment of type 2 diabetes and disorders associated with insulin resistance. Metformin is also used in the treatment of pregnancy disorders such as gestational diabetes. However, the consequences of foetal exposure to metformin on the fertility of exposed offspring remain poorly documented. In this study, we investigated the effect of in utero metformin exposure on the fertility of female and male offspring. We observed that metformin is detectable in the blood of the mother and in amniotic fluid and blood of the umbilical cord. Metformin was not measurable in any tissues of the embryo, including the gonads. The effect of metformin exposure on offspring was sex specific. The adult females that had been exposed to metformin in utero presented no clear reduction in fertility. However, the adult males that had been exposed to metformin during foetal life exhibited a 30% reduction in litter size compared with controls. The lower fertility was not due to a change in sperm production or the motility of sperm. Rather, the phenotype was due to lower sperm head quality - significantly increased spermatozoa head abnormality with greater DNA damage - and hypermethylation of the genomic DNA in the spermatozoa associated with lower expression of the ten-eleven translocation methylcytosine dioxygenase 1 (TET1) protein. In conclusion, while foetal metformin exposure did not dramatically alter gonad development, these results suggest that metabolic modification by metformin during the foetal period could change the expression of epigenetic regulators such as Tet1 and perturb the genomic DNA in germ cells, changes that might contribute to a reduced fertility.

Is Metformin a Possible Beneficial Treatment for Psoriasis? A Scoping Review

Psoriasis is a chronic inflammatory condition with genetic, immunological, and metabolic etiology. The link between psoriasis and diabetes mellitus has been shown in genetic predisposition, environmental influences, inflammatory pathways, and insulin resistance, resulting in end-organ damage in both conditions. Because comorbidities often accompany psoriasis, the therapeutic management of the disease must also take into consideration the comorbidities. Given that metformin’s therapeutic role in psoriasis is not yet fully elucidated, we raised the question of whether metformin is a viable alternative for the treatment of psoriasis. We conducted this scoping review by searching for evidence in PubMed, Cochrane, and Scopus databases, and we used an extension for scoping reviews (PRISMA-ScR). Current evidence suggests that metformin is safe to use in psoriasis. Studies have shown an excellent therapeutic response to metformin in patients with psoriasis and comorbidities such as diabetes, metabolic syndrome, and obesity. There is no clear evidence supporting metformin monotherapy in patients with psoriasis without comorbidities. There is a need to further evaluate metformin in larger clinical trials, as a therapy in psoriasis.