From Implantation to Birth: Insight into Molecular Melatonin Functions.

Melatonin is a lipophilic hormone synthesized and secreted mainly in the pineal gland, acting as a neuroendocrine transducer of photoperiodic information during the night. In addition to this activity, melatonin has shown an antioxidant function and a key role as regulator of physiological processes related to human reproduction. Melatonin is involved in the normal outcome of pregnancy, beginning with the oocyte quality, continuing with embryo implantation, and finishing with fetal development and parturition. Melatonin has been shown to act directly on several reproductive events, including folliculogenesis, oocyte maturation, and corpus luteum (CL) formation. The molecular mechanism of action has been investigated through several studies which provide solid evidence on the connections between maternal melatonin secretion and embryonic and fetal development. Melatonin administration, reducing oxidative stress and directly acting on its membrane receptors, melatonin thyroid hormone receptors (MT1 and MT2), displays effects on the earliest phases of pregnancy and during the whole gestational period. In addition, considering the reported positive effects on the outcomes of compromised pregnancies, melatonin supplementation should be considered as an important tool for supporting fetal development, opening new opportunities for the management of several reproductive and gestational pathologies.

Effect of myo-inositol and melatonin versus myo-inositol, in a randomized controlled trial, for improving in vitro fertilization of patients with polycystic ovarian syndrome.

Polycystic ovarian syndrome (PCOS) induces anovulation in women of reproductive age, and is one of the pathological factors involved in the failure of in vitro fertilization (IVF). Indeed, PCOS women are characterized by poor quality oocytes. Therefore, a treatment for enhancing oocyte quality becomes crucial for these patients. Myo-Inositol and melatonin proved to be efficient predictors for positive IVF outcomes, correlating with high oocyte quality. We tested the synergistic effect of myo-inositol and melatonin in IVF protocols with PCOS patients in a randomized, controlled, double-blind trial. Five-hundred twenty-six PCOS women were divided into three groups: Controls (only folic acid: 400 mcg), Group A (Inofolic® plus, a daily dose of myo-inositol: 4000 mg, folic acid: 400 mcg, and melatonin: 3 mg), and Group B (Inofolic®, a daily dose of myo-inositol: 4000 mg, and folic acid: 400 mcg). The main outcome measures were oocyte and embryo quality, clinical pregnancy and implantation rates. The treatment lasted from the first day of the cycle until 14 days after embryo transfer. Myo-inositol and melatonin have shown to enhance, synergistically, oocyte and embryo quality. In consideration of the beneficial effect observed in our trial and on the bases of previous studies, we decided to integrate routinely MI and M supplementation in the IVF protocols. The same treatment should be taken carefully in consideration in all procedures of this kind.

Ovulation induction with myo-inositol alone and in combination with clomiphene citrate in polycystic ovarian syndrome patients with insulin resistance.

BACKGROUND: Insulin resistance plays a key role in the pathogenesis of polycystic ovarian syndrome (PCOS). One of the methods for correcting insulin resistance is using myo-inositol. AIM: The aim of the present study is to evaluate the effectiveness of myo-inositol alone or in combination with clomiphene citrate for (1) induction of ovulation and (2) pregnancy rate in anovulatory women with PCOS and proven insulin resistance. PATIENTS AND METHODS: This study included 50 anovulatory PCOS patients with insulin resistance. All of them received myo-inositolduring three spontaneous cycles. If patients remained anovulatory and/or no pregnancy was achieved, combination of myo-inositol and clomiphene citrate was used in the next three cycles. Ovulation and pregnancy rate, changes in body mass index (BMI) and homeostatic model assessment (HOMA) index and the rate of adverse events were assessed. RESULTS: After myo-inositol treatment, ovulation was present in 29 women (61.7%) and 18 (38.3%) were resistant. Of the ovulatory women, 11 became pregnant (37.9%). Of the 18 myo-inositol resistant patients after clomiphene treatment, 13 (72.2%) ovulated. Of the 13 ovulatory women, 6 (42.6%) became pregnant. During follow-up, a reduction of body mass index and HOMA index was also observed. CONCLUSION: Myo-inositol treatment ameliorates insulin resistance and body weight, and improves ovarian activity in PCOS patients.

Results from the International Consensus Conference on myo-inositol and D-chiro-inositol in Obstetrics and Gynecology--assisted reproduction technology.

A substantial body of research on mammalian gametogenesis and human reproduction has recently investigated the effect of myo-inositol (MyoIns) on oocyte and sperm cell quality, due to its possible application to medically assisted reproduction. With a growing number of both clinical and basic research papers, the meaning of several observations now needs to be interpreted under a solid and rigorous physiological framework. The 2013 Florence International Consensus Conference on Myo- and D-chiro-inositol in obstetrics and gynecology has answered a number of research questions concerning the use of the two stereoisomers in assisted reproductive technologies. Available clinical trials and studies on the physiological and pharmacological effects of these molecules have been surveyed. Specifically, the physiological involvement of MyoIns in oocyte maturation and sperm cell functions has been discussed, providing an answer to the following questions: (1) Are inositols physiologically involved in oocyte maturation? (2) Are inositols involved in the physiology of spermatozoa function? (3) Is treatment with inositols helpful within assisted reproduction technology cycles? (4) Are there any differences in clinical efficacy between MyoIns and D-chiro-inositol? The conclusions of this Conference, drawn depending on expert panel opinions and shared with all the participants, are summarized in this review paper.

Improving fertilization rate in ICSI cycles by adding myoinositol to the semen preparation procedures: a prospective, bicentric, randomized trial on sibling oocytes.

PURPOSE: To evaluate whether the in vitro incubation of spermatozoa with myoinositol may improve the fertilization rate in ICSI cycles. METHODS: This is a prospective, bicentric, randomized study on 500 MII sibling oocytes injected in 78 ICSI cycles performed between March and October 2013. Randomization of the oocytes into two groups was performed at the time of the denudation. Fertilization rates (per oocyte injected with spermatozoa treated with myoinositol versus per oocyte injected with spermatozoa treated with placebo) were measured as primary outcome and embryo morphology as secondary outcome. Clinical outcomes were also documented. RESULT (S): Fertilization rate (78.9 ± 28.6% vs 63.2 ± 36.7, P = 0.002) and percentage of grade A embryos on day 3 (59.8 ± 35.6% vs 43.5 ± 41.5, P = 0.019) were significantly higher when spermatozoa were treated in vitro with myoinositol versus placebo. No differences were found for the expanded blastocyst formation rate. CONCLUSION (S): In vitro treatment of spermatozoa with myoinositol may optimize ICSI outcomes by improving the fertilization rate and embryo quality on day 3. The improvement of the number and the quality of embryos available in an ICSI cycle may have clinical utility if these findings can be confirmed.

Improvement of mouse embryo quality by myo-inositol supplementation of IVF media.

OBJECTIVE: Myo-inositol (myoIns) has a positive role in mammalian development and human reproduction. Since experiments on farming species suggest a similar role in preimplantation development, we evaluated the hypothesis that the inclusion of myoIns in human embryo culture media would produce an increase in embryo quality in IVF cycles, using the mouse embryo assay. METHODS: To determine the effect of myoIns on completion of preimplantation development in vitro, one-cell embryos of the inbred C57BL/6N mouse strain were produced by ICSI, cultured in human fertilization media in the presence of myoIns (myoIns+) or in its absence (myoIns-) and evaluated morphologically. Daily progression through cleavage stages, blastocyst production and expansion and blastomere number at 96 hours post fertilization were assessed. RESULTS: Compared to myoIns- embryos, myoIns+ embryos displayed a faster cleavage rate and by the end of preimplantation development, the majority of myoIns+ blastocysts was expanded and formed by a higher number of blastomeres. CONCLUSION: The presence of myoIns resulted in both an increase in proliferation activity and developmental rate of in vitro cultured early mouse embryos, representing a substantial improvement of culture conditions. These data may identify myoIns as an important supplement for human embryo preimplantation culture.

BMP4-induced differentiation of a rat spermatogonial stem cell line causes changes in its cell adhesion properties.

Spermatogonial stem cells (SSCs) are at the basis of the spermatogenic process and are essential for the continuous lifelong production of spermatozoa. Although several factors that govern SSC self-renewal and differentiation have been investigated, the direct effect of such factors on SSCs has not yet been studied, mainly because of the absence of markers to identify SSCs and the lack of effective methods to obtain and culture a pure population of SSCs. We now have used a previously established rat SSC cell line (GC-6spg) to elucidate the role of BMP4 in SSC differentiation. We found that GC-6spg cells cultured in the presence of BMP4 upregulate KIT expression, which is an early marker for differentiating spermatogonia. GC-6spg cells were found to express three BMP4 receptors and the downstream SMAD1/5/8 proteins were phosphorylated during BMP4-induced differentiation. A time-course DNA micro-array analysis revealed a total of 529 differentially regulated transcripts (≥2-fold), including several known downstream targets of BMP4 such as Id2 and Gata2. Pathway analysis revealed that the most affected pathways were those involved in adherens junctions, focal junctions, gap junctions, cell adhesion molecules, and regulation of actin cytoskeleton. Interestingly, among the genes belonging to the most strongly affected adhesion pathways was Cdh1 (known as E-cadherin), an adhesion molecule known to be expressed by a subpopulation of spermatogonia including SSCs. Overall, our results suggest that BMP4 induces early differentiation of SSCs in a direct manner by affecting cell adhesion pathways.

Mice overexpressing the mitochondrial phospholipid hydroperoxide glutathione peroxidase in male germ cells show abnormal spermatogenesis and reduced fertility.

To investigate the physiological effects of mitochondrial phospholipid hydroperoxide glutathione peroxidase (mPHGPx) overexpression during early male germ cell differentiation, we have generated transgenic mice bearing the rat mPhgpx coding sequence driven by the mouse synaptonemal complex protein 1 promoter, allowing the transgene to be specifically activated in the testis from the zygotene to diplotene stages of the first meiotic division. Northern/Western blotting and immunocytochemical analyses of endogenous mPHGPx expression during spermatogenesis showed a low enzyme level in middle-late pachytene spermatocytes, but not in earlier meiotic stages, and a significant increase in mPHGPx content in round spermatids. The histological and terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling analysis of transgenic testes revealed a number of spermatogenetic defects, including primary spermatocyte apoptosis, haploid cell loss, and seminiferous epithelium disorganization. In line with these features, adult transgenic male mice also displayed a reduction in fertility. Results obtained in this study suggest that mPHGPx expression is tightly regulated in pachytene spermatocytes, with any spatial-temporal increase in mPHGPx expression resulting in damage to spermatogenesis and eventual loss of haploid cells. Present findings in the mouse may be of interest to human male fertility.

Second trimester amniotic fluid myo-inositol concentrations in women later developing gestational diabetes mellitus or pregnancy-induced hypertension.

OBJECTIVE: To evaluate myo-inositol concentrations in amniotic fluid in women later developing gestational diabetes and hypertension. METHODS: A retrospective study was carried out with three groups of amniotic fluid samples (15-18 gestational weeks): 30 gestational hypertension pregnancies, 30 gestational diabetes pregnancies, and 30 normal pregnancy. RESULTS: A significant difference was observed in myo-inositol concentrations between the median gestational diabetes values (124.0 µmol/L, IQR 90.0-162.5) and the control group values (79.0 µmol/L, IQR 62.0-107.5), but also with gestational hypertension median values (79.0 µmol/L, IQR 67.75-92.0) (p < 0.001). CONCLUSIONS: This study has shown that myo-inositol concentrations in amniotic fluid increased significantly in women later developing gestational diabetes compared to the control group.

PHGPx in spermatogenesis: how many functions?

Phospholipid hydroperoxide glutathione peroxidase (PHGPx) is a unique intracellular enzyme that directly reduces lipid hydroperoxides in membranes and has the ability to use protein thiol groups as donor substrates. Three isoforms of PHGPx have so far been identified, namely, a mitochondrial, a cytosolic and a nuclear variant. This article is focused on recent evidence demonstrating that (1) mitochondrial and nuclear PHGPx isoforms display a different pattern of expression during male germ cell differentiation; (2) different PHGPx isoforms play specific and independent functions during sperm maturation. The data are discussed in light of the idea that PHGPx is a moonlighting protein, changing roles depending on the intracellular localization, expression in a specific cell type and different partners which it interacts with.

Results from the International Consensus Conference on Myo-inositol and d-chiro-inositol in Obstetrics and Gynecology: the link between metabolic syndrome and PCOS.

In recent years, interest has been focused to the study of the two major inositol stereoisomers: myo-inositol (MI) and d-chiro-inositol (DCI), because of their involvement, as second messengers of insulin, in several insulin-dependent processes, such as metabolic syndrome and polycystic ovary syndrome. Although these molecules have different functions, very often their roles have been confused, while the meaning of several observations still needs to be interpreted under a more rigorous physiological framework. With the aim of clarifying this issue, the 2013 International Consensus Conference on MI and DCI in Obstetrics and Gynecology identified opinion leaders in all fields related to this area of research. They examined seminal experimental papers and randomized clinical trials reporting the role and the use of inositol(s) in clinical practice. The main topics were the relation between inositol(s) and metabolic syndrome, polycystic ovary syndrome (with a focus on both metabolic and reproductive aspects), congenital anomalies, gestational diabetes. Clinical trials demonstrated that inositol(s) supplementation could fruitfully affect different pathophysiological aspects of disorders pertaining Obstetrics and Gynecology. The treatment of PCOS women as well as the prevention of GDM seem those clinical conditions which take more advantages from MI supplementation, when used at a dose of 2g twice/day. The clinical experience with MI is largely superior to the one with DCI. However, the existence of tissue-specific ratios, namely in the ovary, has prompted researchers to recently develop a treatment based on both molecules in the proportion of 40 (MI) to 1 (DCI).

Soft gel capsules improve melatonin's bioavailability in humans.

OBJECTIVE: Oral bioavailability is one of the most important properties in drug design and development. A poor oral bioavailability can result in low efficacy and unpredictable response to a drug. Several dosages of melatonin have been used for various investigations to clarify its bioavailability in humans. Aiming to search for a pharmaceutical form, which is better absorbed, the pharmacokinetic (PK) profile of the new manufactured melatonin soft gelatin (soft gel) capsule form has been evaluated and compared with the commercially available melatonin powder. RESEARCH DESIGN AND METHODS: A total of 60 healthy volunteers received 1, 3 mg of melatonin powder and 1 mg of melatonin in soft gel capsules. PK profiles were obtained by analysis of melatonin plasma concentration, and the respective melatonin bioavailability was compared. RESULTS: Melatonin soft gel capsule form showed similar PK parameters compared with the highest doses of melatonin in powder form, but its bioavailability was improved. CONCLUSIONS: Soft gel capsules improved the bioavailability of melatonin in humans even when administered dose was reduced. Considering the number of conditions in which melatonin supplementation is recommended, this evidence could support a broader use of melatonin in clinical practice.

The rationale of the myo-inositol and D-chiro-inositol combined treatment for polycystic ovary syndrome.

PCOS is one of the most common endocrine disorders affecting women and it is characterized by a combination of hyper-androgenism, chronic anovulation, and insulin resistance. While a significant progress has recently been made in the diagnosis for PCOS, the optimal infertility treatment remains to be determined. Two inositol isomers, myo-inositol (MI) and D-chiro-inositol (DCI) have been proven to be effective in PCOS treatment, by improving insulin resistance, serum androgen levels and many features of the metabolic syndrome. However, DCI alone, mostly when it is administered at high dosage, negatively affects oocyte quality, whereas the association MI/DCI, in a combination reproducing the plasma physiological ratio (40:1), represents a promising alternative in achieving better clinical results, by counteracting PCOS at both systemic and ovary level.

Hyperinsulinemia Alters Myoinositol to d-chiroinositol Ratio in the Follicular Fluid of Patients With PCOS.

Myoinositol (MI) and d-chiroinositol (DCI) are 2 stereoisomers and insulin sensitizers. Their physiological ratio differs from tissue to tissue, and they are regulated by an insulin-dependent epimerase whose activity is drastically reduced in conditions of insulin resistance. Based on literature data and on the fact that MI phospholipids are follicle-stimulating hormone (FSH) second messengers, we speculated that patients with polycystic ovary syndrome (PCOS) having hyperinsulinemia, present an enhanced MI to DCI epimerization in the ovary, leading to MI deficiency that impairs FSH signaling, resulting in reduced oocyte quality. In the present study, 20 patients with PCOS and 20 healthy women were enrolled for measurement of MI and DCI levels in their follicular fluid. Follicular fluid samples were taken using a vaginal probe and both MI and DCI were quantified analytically. Results showed that the ratio of MI-DCI dropped from 100:1 in healthy participants to 0.2:1 in patients with PCOS who additionally displayed significantly higher levels of insulin resistance, hyperinsulinemia, and luteinizing hormone. This study is the first one to analyze the misbalance in the MI-DCI ratio in the ovary of patients with PCOS, supporting the concept that maintaining the physiological levels of the 2 stereoisomers is crucial, in restoring the ovarian functionality.

Myo-inositol in a new pharmaceutical form: a step forward to a broader clinical use.

OBJECTIVE: Dose-dependent side effects related to myo-inositol (MI) oral administration represent a significant shortcoming for its clinical use. Aiming to search for a pharmaceutical form able to be better absorbed, the pharmacokinetic (PK) profile of the new manufactured MI soft gelatin capsule form was evaluated and compared with the commercially available MI powder. RESEARCH DESIGN AND METHODS: A single-dose relative trial, consisting of four phases, was performed on 20 healthy volunteers who received different doses of MI powder and MI soft gelatin capsules. PK profiles related to the two pharmaceutical forms were obtained by analysis of MI plasma concentration, and the respective MI bioavailability was compared. RESULTS: The administration of MI powder and MI soft gelatin capsules resulted in a different bioavailability. MI soft gelatin capsule form showed similar PK parameters compared with three times higher doses of MI in powder form. CONCLUSIONS: MI soft gelatin capsules displayed an improved bioavailability, allowing to substantially reduce the administered dose and to minimize the dose-dependent side effects. Considering the number of conditions in which MI supplementation is recommended, this evidence could support a broader use of MI in clinical practice.

Myo-inositol soft gel capsules may prevent the risk of coffee-induced neural tube defects.

OBJECTIVE: Neural tube defects (NTDs) are classified as folate sensitive (about 70%) and folate resistant (about 30%); although folic acid is able to prevent the former, several data have shown that inositol may prevent the latter. It has recently been proposed that coffee intake might represent a risk factor for NTD, likely by interfering with the inositol signaling. In the present study, we tested the hypothesis that, beside affecting the inositol signaling pathway, coffee also interferes with inositol absorption. RESEARCH DESIGN AND METHODS: In order to evaluate coffee possible negative effects on inositol gastrointestinal absorption, a single-dose bioavailability trial was conducted. Pharmacokinetics (PK) parameters of myo-inositol (MI) powder and MI soft gelatin capsules swallowed with water and with a single 'espresso' were compared. PK profiles were obtained by analysis of MI plasma concentration, and the respective MI bioavailability was compared. RESULTS: Myo-inositol powder administration was negatively affected by coffee intake, thus suggesting an additional explanation to the interference between inositol deficiency and coffee consumption. On the contrary, the concomitant single 'espresso' consumption did not affect MI absorption following MI soft gelatin capsules administration. Furthermore, it was observed that MI soft gelatin capsule administration resulted in improved bioavailability compared to the MI powder form. CONCLUSIONS: Myo-inositol soft gelatin capsules should be considered for the preventive treatment of NTDs in folate-resistant subjects due to their higher bioavailability and to the capability to reduce espresso interference.

The D-chiro-inositol paradox in the ovary.

The D-chiro-inositol-to-myo-inositol ratio is regulated by an insulin-dependent epimerase. Enzyme activity varies among tissues, likely owing to the specific needs of the two different molecules. We hypothesize that in the ovaries of polycystic ovary syndrome patients, epimerase activity is enhanced, leading to a local myo-inositol deficiency which in turn is responsible for the poor oocyte quality.