Myo-Inositol and D-Chiro-Inositol as Modulators of Ovary Steroidogenesis: A Narrative Review

Saliva and plasma metabolome changes during anoestrus, the oestrous cycle and early gestation in the mare: A pilot study

Successful reproductive management of domestic mammals depends primarily upon timely identification of oestrous cycle stages. There is a need to develop an alternative non-invasive, welfare-friendly, accurate and reliable method to identify reproductive cycle stages. This is of particular interest for horse breeders, because horses are high-value farm animals that require careful management and individual monitoring. Saliva sampling is non-invasive, painless and welfare-friendly. Thus, we performed a metabolomic analysis of equine saliva during different reproductive stages to identify changes in the salivary metabolome during anoestrus, the oestrous cycle and early gestation. We compared the saliva and plasma metabolomes to investigate the relationship between the two fluids according to the physiological stage. We collected saliva and plasma samples from six mares during seasonal anoestrus, during the follicular phase 3 days, 2 days and 1 day before ovulation and the day when ovulation was detected, during the luteal phase 6 days after ovulation, and during early gestation 18 days after ovulation and insemination. Metabolome analysis was performed by proton-nuclear magnetic resonance spectroscopy. We identified 58 and 51 metabolites in saliva and plasma, respectively. The levels of four metabolites or groups of metabolites in saliva and five metabolites or groups of metabolites in plasma showed significant modifications during the 4 days until ovulation, ie 3 days prior to and on the day of ovulation. The levels of 11 metabolites or groups of metabolites in saliva and 17 metabolites or groups of metabolites in plasma were significantly different between the seasonal anoestrus and the ovarian cyclicity period. The physiological mechanisms involved in the onset of ovarian cyclicity and in ovulation induced modifications of the metabolome both in plasma and saliva. The metabolites whose salivary levels changed during the reproductive cycle could be potential salivary biomarkers to detect the reproductive stage in a welfare friendly production system. In particular, we propose creatine and alanine as candidate salivary biomarkers of ovulation and of the onset of ovarian cyclicity, respectively. However, extensive validation of their reliability is required. Our study contributes to extend to domestic mammals the use of saliva as a non-invasive alternative diagnostic fluid for reproduction in a welfare-friendly production system.

A rapid and validated GC-MS/MS method for simultaneous quantification of serum Myo- and D-chiro-inositol isomers

BACKGROUND

Myo-inositol (MI) and D-chiro-inositol (DCI) are two paramount isomers of inositol, both vital in glucose and steroid metabolism. Deficits in MI, DCI or MI/DCI ratio are expressly concerned with several pathological process, whereas MI and DCI lack practical measurement for human specimen.

METHODS

To quantify MI and DCI in serum samples simultaneously, a gas chromatography tandem mass spectrometry (GC-MS/MS) method was established. The process flow was optimized in ion source, derivative agent volume and reaction time. The performance characteristics were verified by commercial standards and clinical serums.

RESULTS

This method was confirmed to be sensitive (LOD ≤ 30 ng/mL of MI, ≤3 ng/mL of DCI) and reproducible (RSD < 6 % for repeated analyses). Quantitative determinations performed good linearity within the measurement range of 0.500-10.00 and 0.005-0.500 μg/mL for MI and DCI respectively (R2 > 0.999). The recoveries of MI and DCI were 97.11-99.35 % and 107.82-113.09 %, respectively. This method was successfully applied to 114 clinical specimens. No significant matrix effect was observed in serum samples under current conditions.

Inositols and female reproduction disorders: a consensus statement from the working group of the Club of the Italian Society of Endocrinology (SIE)-Women's Endocrinology

PURPOSE

To provide the latest scientific knowledge on the efficacy of inositols for improving reproductive disorders in women with and without polycystic ovary syndrome (PCOS) and to reach a consensus on their potential use through a Delphi-like process.

METHODS

A panel of 17 endocrinologists and 1 gynecologist discussed 4 key domains: menses irregularity and anovulation, fertility, pregnancy outcomes, and neonatal outcomes.

RESULTS

A total of eight consensus statements were drafted. Myo-inositol (Myo) supplementation can be used to improve menses irregularities and anovulation in PCOS. Myo supplementation can be used in subfertile women with or without PCOS to reduce the dose of r-FSH for ovarian stimulation during IVF, but it should not be used to increase the clinical pregnancy rate or live birth rate. Myo supplementation can be used in the primary prevention of gestational diabetes mellitus (GDM), but should not be used to improve pregnancy outcomes in women with GDM. Myo can be preconceptionally added to folic acid in women with a previous neural tube defects (NTD)-complicated pregnancy to reduce the risk of NTDs in newborns. Myo can be used during pregnancy to reduce the risk of macrosomia and neonatal hypoglycemia in mothers at risk of GDM.

CONCLUSION

This consensus statement provides recommendations aimed at guiding healthcare practitioners in the use of inositols for the treatment or prevention of female reproductive disorders. More evidence-based data are needed to definitively establish the usefulness of Myo, the appropriate dosage, and to support the use of D-chiro-inositol (DCI) or a definitive Myo/DCI ratio.

Inositol Restores Appropriate Steroidogenesis in PCOS Ovaries Both In Vitro and In Vivo Experimental Mouse Models

Androgen excess is a key feature of several clinical phenotypes of polycystic ovary syndrome (PCOS). However, the presence of FSH receptor (FSHR) and aromatase (CYP19A1) activity responses to physiological endocrine stimuli play a critical role in the pathogenesis of PCOS. Preliminary data suggest that myo-Inositol (myo-Ins) and D-Chiro-Inositol (D-Chiro-Ins) may reactivate CYP19A1 activity. We investigated the steroidogenic pathway of Theca (TCs) and Granulosa cells (GCs) in an experimental model of murine PCOS induced in CD1 mice exposed for 10 weeks to a continuous light regimen. The effect of treatment with different combinations of myo-Ins and D-Chiro-Ins on the expression of Fshr, androgenic, and estrogenic enzymes was analyzed by real-time PCR in isolated TCs and GCs and in ovaries isolated from healthy and PCOS mice. Myo-Ins and D-Chiro-Ins, at a ratio of 40:1 at pharmacological and physiological concentrations, positively modulate the steroidogenic activity of TCs and the expression of Cyp19a1 and Fshr in GCs. Moreover, in vivo, inositols (40:1 ratio) significantly increase Cyp19a1 and Fshr. These changes in gene expression are mirrored by modifications in hormone levels in the serum of treated animals. Myo-Ins and D-Chiro-Ins in the 40:1 formula efficiently rescued PCOS features by up-regulating aromatase and FSHR levels while down-regulating androgen excesses produced by TCs.

Causal effects of genetically determined metabolites on androgenetic alopecia: A two-sample Mendelian randomization analysis

BACKGROUND

Androgenic alopecia (AGA) is the most common non-scarring alopecia disorder. Given its increasing incidence and onset during adolescence, AGA significantly impacts both the physical and psychological well-being of affected individuals. Emerging evidence suggests a pivotal role of metabolites in AGA. This study aims to elucidate the causal relationship between metabolites and AGA using Mendelian randomization (MR) analysis.

METHODS

We conducted a two-sample Mendelian randomization (TSMR) analysis based on a genome-wide association study (GWAS) to assess the causality of 452 metabolites on AGA. The main approach employed for inferring causal effects was inverse variance weighted (IVW), which was complemented by MR-Egger regression, weighted median, as well as MR pleiotropy residual sum and outlier (MR-PRESSO) approaches. Additionally, sensitivity analyses were performed to ensure result robustness. Single nucleotide polymorphisms (SNPs) were selected as instrumental variables (IVs) in GWAS dataset comprising 452 metabolites.

RESULTS

Notably, we identified Scyllo-inositol and Alpha-ketoglutarate as the most potent protective factors against AGA, while Heme* and 2-palmitoylglycerophosphocholine* emerged as significant risk factors for AGA. Furthermore, sensitivity analysis revealed no heterogeneity in these findings.

CONCLUSIONS

Overall, our research suggests a potential causal link between metabolites and AGA, offering a more comprehensive insight into the pathogenesis of AGA and present additional strategies for prevention and treatment.

<sc>d</sc>-Chiro-Inositol in Clinical Practice: A Perspective from the Experts Group on Inositol in Basic and Clinical Research (EGOI)

BACKGROUND

d-Chiro-inositol is a natural molecule that, in association with its well-studied isomer myo-inositol, may play a role in treating various metabolic and gynecological disorders.

OBJECTIVES

This perspective seeks to explore the mechanisms and functions of d-chiro-inositol, laying the foundations to discuss its use in clinical practice, across dysmetabolism, obesity, and hormonal dysregulation.

METHODS

A narrative review of all the relevant papers known to the authors was conducted.

OUTCOME

d-Chiro-inositol acts through a variety of mechanisms, acting as an insulin sensitizer, inhibiting the transcription of aromatase, in addition to modulating white adipose tissue/brown adipose tissue transdifferentiation. These different modes of action have potential applications in a variety of therapeutic fields, including PCOS, dysmetabolism, obesity, hypoestrogenic/hyperandrogenic disorders, and bone health.

CONCLUSIONS

d-Chiro-inositol mode of action has been studied in detail in recent years, resulting in a clear differentiation between d-chiro-inositol and its isomer myo-inositol. The insulin-sensitizing activities of d-chiro-inositol are well understood; however, its potential applications in other fields, in particular obesity and hyperestrogenic/hypoandrogenic disorders in men and women, represent promising avenues of research that require further clinical study.

Myo-inositol in assisted reproductive technology from bench to bedside

Inositols are insulin-sensitizing compounds of promising efficacy in the management of polycystic ovary syndrome (PCOS). On the one hand, myo-inositol (myo-ins) plays a regulatory role in male and female reproductive function, influencing the development of oocytes, spermatozoa, and embryos. On the other hand, high concentrations of D-chiro-inositol (D-chiro-ins) in the ovary may adversely affect oocyte quality. This review analyses the available literature, which encourages the clinical use of myo-ins in assisted reproductive technologies (ARTs) due to its beneficial effects on female and male reproduction.

Androgen excess: a hallmark of polycystic ovary syndrome

Polycystic ovarian syndrome (PCOS) is a metabolic, reproductive, and psychological disorder affecting 6-20% of reproductive women worldwide. However, there is still no cure for PCOS, and current treatments primarily alleviate its symptoms due to a poor understanding of its etiology. Compelling evidence suggests that hyperandrogenism is not just a primary feature of PCOS. Instead, it may be a causative factor for this condition. Thus, figuring out the mechanisms of androgen synthesis, conversion, and metabolism is relatively important. Traditionally, studies of androgen excess have largely focused on classical androgen, but in recent years, adrenal-derived 11-oxygenated androgen has also garnered interest. Herein, this Review aims to investigate the origins of androgen excess, androgen synthesis, how androgen receptor (AR) signaling mediates adverse PCOS traits, and the role of 11-oxygenated androgen in the pathophysiology of PCOS. In addition, it provides therapeutic strategies targeting hyperandrogenism in PCOS.

Treatment with Myo-Inositol Does Not Improve the Clinical Features in All PCOS Phenotypes

BACKGROUND

The aim of the present study is to investigate the effects produced by a treatment with myo-Inositol (myo-Ins) in women presenting polycystic ovary syndrome (PCOS) of different phenotypes.

METHODS

We performed a retrospective study to evaluate whether patients presenting different PCOS phenotypes, treated for 6 months with myo-Ins, might exhibit a differential response to the treatment. On this premise, we clustered women with PCOS phenotypes A, B, and C in the first study group (hyperandrogenic PCOS or H-PCOS), and women presenting PCOS phenotype D in a separate study group (non-hyperandrogenic PCOS or NH-PCOS) to evaluate if the presence of hyperandrogenism, shared by H-PCOS, might imply a metabolic/endocrine condition rather than a gynecological issue.

RESULTS

The administration of myo-Ins induced a significant improvement in metabolic and endocrine parameters in H-PCOS, while the effects on NH-PCOS were negligible. Additionally, myo-Ins treatment improved the endometrial thickness of H-PCOS.

CONCLUSIONS

Subjects selected for the study exhibited a differential response to myo-Ins therapy according to their PCOS phenotypes. The data suggest that the same treatment might not equally improve the parameters of the PCOS condition in each sub-group of patients. It is crucial to distinguish the various phenotypes to properly select the therapeutical approach.

D-Chiro-Inositol in Endometrial Hyperplasia: A Pilot Study

Endometrial hyperplasia is a threatening pathology driven by unopposed estrogen stimulus. Moreover, insulin may act on the endometrium, prompting further growth. We aimed at assessing whether D-chiro-Inositol, an insulin sensitizer with estrogen-lowering properties, might improve the condition of patients with simple endometrial hyperplasia without atypia. We enrolled women with simple endometrial hyperplasia without atypia and related symptoms, including abnormal uterine bleeding. We treated the patients with one tablet per day, containing 600 mg of D-chiro-inositol for six months. Patients underwent ultrasound to assess the thickness of the endometrium at baseline, after three months, and at the end of this study. Endometrial thickness went from 10.82 ± 1.15 mm to 8.00 ± 0.81 mm after three months (p < 0.001) and to 6.9 ± 1.06 mm after six months (p < 0.001 versus baseline; p < 0.001 versus three months). D-chiro-inositol treatment also improved heavy menstrual bleeding and the length of menstruation. Despite the fact that our data should be validated in larger studies with appropriate control groups, our promising results support the hypothesis that D-chiro-inositol may represent a useful treatment in the case of endometrial hyperplasia without atypia.